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Zusammenfassung

The repeatability and control of the achievable surface integrity in manual loose-abrasive diamond polishing of workpieces is very limited. In this study, first effects of polishing on the surface roughness and on induced near-surface residual stress of hardened tool steel X37CrMoV5-1 using an automatic metallographic grinder polisher have been investigated. The results show different effects of polishing parameters such as grain size, platen speed and forces applied to the workpiece on roughness and residual stress. XRD measurements of the residual stress depth profile showed a reduction in compressive stress which could be explained by the material removal mechanism and direction.

Zusammenfassung

The current demand for highly sensitive, optical sensors in biodiagnostics has prompted the development of ultrathin metal coatings on a range of substrates. Given the potential attenuation of the signal from a plasmonic sensor for the detection of fluorescent molecules when an adhesion layer between the substrate and coating is employed, this study examines the impact of various factors on the adhesion strength between gold coatings and substrates comprising glass and cyclo-olefin-polymer (COP). The objective is to identify potential configurations for high adhesion strength, thereby eliminating the need for an adhesion layer in the fabrication of optical sensors with gold coatings for diagnostic applications or to utilize a minimal adhesion layer thickness. The influence of pretreatments prior to coating deposition with oxygen plasma, ultrathin adhesion layers of titanium as well as the impact of thermal shock tests with various cycles on the coating’s integrity are investigated. Two methods of adhesion strength testing were applied to ultrathin coatings on glass and polymer substrates. Cross-cut and nano scratch tests were used to assess the adhesion of the ultrathin metal layers, which provided qualitative and quantitative results. The results of the two test methods on glass substrates are in good accordance, demonstrating the highest adhesion strength for gold coatings on glass with an adhesion layer, in combination with or without plasma treatment. The cross-cut testing on COP demonstrates a constant high adhesion strength when using an adhesion layer alone or without any pretreatment, while a low adhesion strength is observed in combination with plasma treatment. Following the thermal shock test, alterations in adhesion strength were observed for the remaining configurations. The rise in the coefficient of thermal expansion of COP between +30 and 85 °C in comparison to lower temperatures, as evidenced by thermomechanical analysis, may account for the disparate adhesion strengths of COP following thermal shock tests.

Zusammenfassung

Voltage standards are widely used to transfer volts from Josephson voltage standards (JVSs) at national metrology institutes (NMIs) into calibration labs to maintain the volts and to transfer them to test equipment at production lines. Therefore, commercial voltage standards based on Zener diodes are used. Analog Devices Inc. (San Jose, CA, USA), namely, Eric Modica, introduced the ADR1000KHZ, a successor to the legendary LTZ1000, at the Metrology Meeting 2021. The first production samples were already available prior to this event. In this article, this new temperature-stabilized Zener diode is compared to several others as per datasheet specifications. Motivated by the superior parameters, a 10 V transfer standard prototype for laboratory use with commercial off-the-shelf components such as resistor networks and chopper amplifiers was built. How much effort it takes to reach the given parameters was investigated. This paper describes how the reference was set up to operate it at its zero-temperature coefficient (z.t.c.) temperature and to lower the requirements for the oven stability. Furthermore, it is shown how the overall temperature coefficient (t.c.) of the circuit was reduced. For the buffered Zener voltage, a t.c. of almost zero, and with amplification to 10 V, a t.c. of <0.01 µV/V/K was achieved in a temperature span of 15 to 31 °C. For the buffered Zener voltage, a noise of ~584 nVp-p and for the 10 V output, ~805 nVp-p were obtained. Finally, 850 days of drift data were taken by comparing the transfer standard prototype to two Fluke 7000 voltage standards according to the method described in NBS Technical Note 430. The drift specification was, however, not met.

Zusammenfassung

The demand for individualized products is continuously increasing. For this purpose, product development processes are already established in companies. However, these processes are typically based on mass products and are not necessarily suitable for individualized products. Hence, the question emerges of how to develop and manufacture individualized products in a corporate product development setup. The characteristics of individualized products and a multiple-case study in seven companies made apparent that product development processes for complex individualized products should be adapted according to the specific requirements and relate to specific product development methods. More specifically, results indicate that a prior definition and assurance of boundaries as well as free spaces through pretested products is key, as the validation stage is constrained for such products. Methods such as in-process monitoring, postprocessing, and responsibility sharing (co-design) and the use of expert tools foster such product development processes. That gives practitioners the possibility to develop and manufacture individualized products efficiently by adapting the product development process and using the right methods. Based on these results and the literature review, we propose a novel definition of individualized products and a holistic product development process that may support discussions of the relevance of mass individualization as a new paradigm.

Zusammenfassung

This paper investigates the utilization of digital printing technologies for the fabrication of low temperature co-fired ceramics (LTCC). LTCC offer great opportunities for applications such as antennas, sensors or actuators due to their outstanding properties like low dielectric loss, low permittivity, low coefficient of thermal expansion and at the same time high reliability in harsh environments (heat, humidity, and radiation). LTCC are multilayer circuits that are typically functionalized by screen-printing. This publication investigates the replacement of screen-printing by digital printing processes, such as inkjet and Aerosol Jet printing, to facilitate a more resource-friendly and customizable manufacturing of LTCC. The use of digital printing technologies not only streamlines small-scale productions and development processes but also offers the advantage of achieving miniaturization down to single-digit microns. In this publication, digital printing processes, filling of vias, lamination processes, co-firing at 850 °C and printing on fired LTCC were investigated. Three layers of nanoparticle silver ink were printed on green LTCC tape and 100% of the embedded printed structures were conductive after co-firing. Filling of vias with inkjet printing was investigated and the most important process parameters were found to be the clustering of vias, the amount of active nozzles and the substrate temperature. Printing on fired LTCC demonstrated high precision, and sintering at 600 °C achieved strong adhesion of printed structures to LTCC. These successful findings culminate in presenting a process chain for fully maskless structured, multilayer LTCC.

Zusammenfassung

In this work, the detection mode coupling of multi-axis MEMS gyroscopes is investigated in theory and experiment. First, the impact of bending stress on the transfer behavior of the detection modes is evaluated by actuating the modes with test signals. It is shown experimentally, that by applying bending stress, the mode coupling is significantly increased. Additional to that, cross-axis sensitivity (CAS) is measured with the same setup. In the second part of the paper, theoretical descriptions of the detection mode coupling are developed. By comparing the experimental results with the theory, it is demonstrated, that spring coupling is the dominant coupling mechanism that induces the mode coupling with bending stress. In this work, cross-axis sensitivity is investigated with respect to bending stress and a further aspect towards understanding the origins of cross-axis sensitivity is provided.

Zusammenfassung

Biologization of biomaterials with endothelial cells (ECs) is an important step in vascular tissue engineering, aiming at improving hemocompatibility and diminishing the thrombo-inflammatory response of implants. Since subcellular topography in the scale of nano to micrometers can influence cellular adhesion, proliferation, and differentiation, we here investigate the effect of surface roughness on the endothelialization of gelatin hydrogel scaffolds. Considering the micron and sub-micron features of the different native tissues underlying the endothelium in the body, we carried out a biomimetic approach to replicate the surface roughness of tissues and analyzed how this impacted the adhesion and proliferation of human umbilical endothelial cells (HUVECs). Using an imprinting technique, nano and micro-roughness ranging from Sa= 402 nm to Sa= 8 μm were replicated on the surface of gelatin hydrogels. Fluorescent imaging of HUVECs on consecutive days after seeding revealed that microscale topographies negatively affect cell spreading and proliferation. By contrast, nanoscale roughnesses of Sa= 402 and Sa= 538 nm promoted endothelialization as evidenced by the formation of confluent cell monolayers with prominent VE-cadherin surface expression. Collectively, we present an affordable and flexible imprinting method to replicate surface characteristics of tissues on hydrogels and demonstrate how nanoscale roughness positively supports their endothelialization.

Zusammenfassung

Substrate materials for printed circuit boards must meet ever-increasing requirements to keep up with electronics technology development. Especially in the field of high-frequency applications such as radar and cellular broadcasting, low permittivity and the dielectric loss factor are key material parameters. In this work, the dielectric properties of a high-temperature, thermoplastic PEEK/PEI blend system are investigated at frequencies of 5 and 10 GHz under dried and ambient conditions. This material blend, modified with a suitable filler system, is capable of being used in the laser direct structuring (LDS) process. It is revealed that the degree of crystallinity of neat PEEK has a notable influence on the dielectric properties, as well as the PEEK phase structure in the blend system developed through annealing. This phenomenon can in turn be exploited to minimize permittivity values at 30 to 40 wt.-% PEI in the blend, even taking into account the water uptake present in thermoplastics. The dielectric loss follows a linear mixing rule over the blend range, which proved to be true also for PEEK/PEI LDS compounds.

Zusammenfassung

This paper discusses the possibility of using two-mode squeezed light to improve the performance of existing sensor technology with the focus on its miniaturization under realistic losses. Therefore, we analyze a system consisting of a part for two-mode squeezed light generation, a sensor region, and a detection stage. Based on a general four-wave mixing (FWM) Hamiltonian caused by third-order susceptibility, we formulate linearized equations that describe the FWM process below the threshold and are used to analyze the squeezing quality of the generated optical signal and idler modes. For a possible realization, the focus is set on chip-integrated generation using microring resonators. To do so, the impacts of the design and the pump light are considered in the derived equations. These equations are used to analyze the usage of two-mode squeezed light in quantum metrology and the application in a Mach-Zehnder interferometer. Due to the impact of losses in realistic use cases, we show that the main usage is for small and compact devices, which can lead to a quantum improvement of up to a factor of 10 in comparison with using coherent light only. This enables the use of small squeezing-enhanced sensors with a performance comparable to larger classical sensors.

Zusammenfassung

Inertial measurement units (IMU) are able to sense the acceleration and rotation rate of a system and are widely used in mass products like mobile phones and toy drones. These different use-cases have various requirements on the IMU in dependency of the occurring environmental influences. These influences are for example stress effects like temperature, humidity or diverse soldering processes which cause the performance of the sensors to suffer. The initial sensor calibration during the manufacturing of the IMUs is not sufficient anymore and the individual further processing and usage reduces this performance. In this work, an approach that increases the performance and improves the stress robustness against environmental influences is presented. This approach self-calibrates each sensor part individually by using a machine-learning technique called meta-learning. This allows to efficiently adapt a general meta-model to different sensor units to achieve an improved stress robustness with only one data sample. While the quadrature signal of IMUs gyroscope is used to demonstrate the performance and behavior of the chosen approach, this method is applicable for a wide range of various sensor systems to speed up the calibration process and to increase the performance for multiple use-cases.

Zusammenfassung

The current industrial revolution derives much of its momentum from value creation based on interconnected products and related data based services. Such products must fulfill both mechanical and electrical requirements, making them mechatronic systems. The production of such systems via additive manufacturing (AM) processes offers advantages in achievable complexity, reduction of the amount of individual components, and cost-effective as well as sustaina ble production of small quantities. In this work, a process chain is presented that allows for refining additively manufactured 3D structures made from industry-standard materials into mechatronic components by creating electrically conductive structures directly on their surfaces. The process chain is based on masking the component's surface and selectively removing the masking according to the circuit geometry using laser radiation. In a wet–chemical bath process, the surface is then exposed to palladium nuclei, the masking is fully removed and metal layers (copper/nickel/gold) are deposited by electroless plating. The procedure is developed using stereolithography as a model process for AM and transferred to four additional AM methods. In all cases, despite markedly different surface properties, good selectivity of metal deposition is observed as well as adhesion strength and conductivity comparable to industrially common injection-molded laser direct structured mechatronic interconnect devices.

Zusammenfassung

Autonomous driving is a key vehicle capability for future mobility solutions that relies on the reliability of its high-performance vehicle computer. As for any electronics for automotive applications, thermal management is a crucial point. A very extensively employed approach for improving heat removal is the usage of heat spreaders in the form of a package lid, especially for flip-chip applications. The usage of a lid in flip-chip ball grid array (BGA) packages improves heat removal based on the heat spreading capabilities of the lid, and reduces package warpage, since with a lid the package becomes stiffer. However, adding a lid also increases stresses at solder interconnects. When selecting a material for the lid, the most intuitive criterion is to focus on the material’s thermal conductivity. Sometimes overlooked, the coefficient of thermal expansion (CTE) of the lid also plays an important role regarding package warpage and reliability of thermal interface materials (TIM) as well as solder interconnects, such as solder bumps. This work focuses on the influence of different lid materials at package level for flip-chip applications. Consequently, the influence of three alternative materials is investigated and compared to the performance of a standard copper lid. For the quantification of the effects, a validated finite element model of a flip-chip package is presented, with the thermo-mechanical performance of the studied lid materials validated based on package warpage, peel strains and plastic strain energy density at the bumps, as well as on peel and shear strains at the TIM.

Zusammenfassung

Autonomous driving is a key vehicle capability for future mobility solutions that relies on the reliability of its high-performance vehicle computer. As for any electronics for automotive applications, thermal management is a crucial point. A very extensively employed approach for improving heat removal is the usage of heat spreaders in the form of a package lid, especially for flip-chip applications. The usage of a lid in flip-chip ball grid array (BGA) packages improves heat removal based on the heat spreading capabilities of the lid, and reduces package warpage, since with a lid the package becomes stiffer. However, adding a lid also increases stresses at solder interconnects. When selecting a material for the lid, the most intuitive criterion is to focus on the material’s thermal conductivity. Sometimes overlooked, the coefficient of thermal expansion (CTE) of the lid also plays an important role regarding package warpage and reliability of thermal interface materials (TIM) as well as solder interconnects, such as solder bumps. This work focuses on the influence of different lid materials at package level for flip-chip applications. Consequently, the influence of three alternative materials is investigated and compared to the performance of a standard copper lid. For the quantification of the effects, a validated finite element model of a flip-chip package is presented, with the thermo-mechanical performance of the studied lid materials validated based on package warpage, peel strains and plastic strain energy density at the bumps, as well as on peel and shear strains at the TIM.

Zusammenfassung

The demand for individualized products is continuously increasing. For this purpose, product development processes are already established in companies. However, these processes are typically based on mass products and are not necessarily suitable for individualized products. Hence, the question emerges of how to develop and manufacture individualized products in a corporate product development setup. The characteristics of individualized products and a multiple-case study in seven companies made apparent that product development processes for complex individualized products should be adapted according to the specific requirements and relate to specific product development methods. More specifically, results indicate that a prior definition and assurance of boundaries as well as free spaces through pretested products is key, as the validation stage is constrained for such products. Methods such as in-process monitoring, postprocessing, and responsibility sharing (co-design) and the use of expert tools foster such product development processes. That gives practitioners the possibility to develop and manufacture individualized products efficiently by adapting the product development process and using the right methods. Based on these results and the literature review, we propose a novel definition of individualized products and a holistic product development process that may support discussions of the relevance of mass individualization as a new paradigm.

Zusammenfassung

Inkjet printing for printed electronics is a growing market due to its advantages, including scalability, various usable materials and its digital, pixel based layout design. An important quality factor is the wetting of the ink on the substrate. This article proposes a workflow to evaluate the print quality of specific layouts by means of image analysis. A self-developed image analysis software, which compares a mask with the actual layout, enables a pixel-based analysis of the wetting behavior by the implementation of two parameters called over- and underwetting rate. A comparison of actual and targeted track widths can be performed for the evaluation of different parameters, such as the tested plasma treatment, drop spacing (DS) and substrate temperature. To prove the functionality of the image analyses tool, the print quality of Au structures inkjet printed on cyclic olefin copolymer (COC) substrates was studied experimentally by varying the three previously mentioned parameters. The experimental results showed that the wetting behavior of Au ink deposited on COC substrates influences various line widths differently, leading to higher spreading for smaller line widths. The proposed workflow is suitable for identifying and evaluating multiple tested parameter variations and might be easily adopted for printers for in-process print quality control in industrial manufacturing.

Zusammenfassung

This work explores intrinsic and extrinsic mechanical stress effects in mode-split, open-loop MEMS gyroscopes. First, the impact of stress on the deformation of a single MEMS die is experimentally investigated with white light interferometry. Only a small amount of the observed deformation of the MEMS die is found to be caused by soldering stress, whereas the main amount originates from the die attach film. In the second part of the paper, zero-rate offset drift across PCB bending is investigated using MEMS gyroscope prototype devices in LGA mold packages. While most of the offset drift can be attributed to changes of quadrature and mechanical phase error as expected, a smaller cross-axis offset contribution is demonstrated as well. Our investigation forms a further building block towards understanding root-causes of cross-axis sensitivity.

Zusammenfassung

Hard coatings can be applied onto microstructured molds to influence wear, form filling and demolding behaviors in microinjection molding. As an alternative to this conventional manufacturing procedure, &ldquo;direct processing&rdquo; of physical-vapor-deposited (PVD) hard coatings was investigated in this study, by fabricating submicron features directly into the coatings for a subsequent replication via molding. Different diamondlike carbon (DLC) and chromium nitride (CrN) PVD coatings were investigated regarding their suitability for focused ion beam (FIB) milling and microinjection molding using microscope imaging and areal roughness measurements. Each coating type was deposited onto high-gloss polished mold inserts. A specific test pattern containing different submicron features was then FIB-milled into the coatings using varied FIB parameters. The milling results were found to be influenced by the coating morphology and grain microstructure. Using injection&ndash;compression molding, the submicron structures were molded onto polycarbonate (PC) and cyclic olefin polymer (COP). The molding results revealed contrasting molding performances for the studied coatings and polymers. For CrN and PC, a sufficient replication fidelity based on AFM measurements was achieved. In contrast, only an insufficient molding result could be obtained for the DLC. No abrasive wear or coating delamination could be found after molding.

Zusammenfassung

The demolding of plastic parts remains a challenging aspect of injection molding. Despite various experimental studies and known solutions to reduce demolding forces, there is still not a complete understanding of the effects that occur. For this reason, laboratory devices and in-process measurement injection molding tools have been developed to measure demolding forces. However, these tools are mostly used to measure either frictional forces or demolding forces for a specific part geometry. Tools that can be used to measure the adhesion components are still the exception. In this study, a novel injection molding tool based on the principle of measuring adhesion-induced tensile forces is presented. With this tool, the measurement of the demolding force is separated from the actual ejection step of the molded part. The functionality of the tool was verified by molding PET specimens at different mold temperatures, mold insert conditions and geometries. It was demonstrated that once a stable thermal state of the molding tool was achieved, the demolding force could be accurately measured with a comparatively low force variance. A built-in camera was found to be an efficient tool for monitoring the contact surface between the specimen and the mold insert. By comparing the adhesion forces of PET molded on polished uncoated, diamond-like carbon and chromium nitride (CrN) coated mold inserts, it was found that a CrN coating reduced the demolding force by 98.5% and could therefore be an efficient solution to significantly improve demolding by reducing adhesive bond strength under tensile loading.

Zusammenfassung

Fiber optic Sagnac interferometer can measure the rotation rate of a system with a high sensitivity. However, they require a large sensor area which leads to a huge footprint and size compared to their MEMS counterpart. Consequently, the performance decreases when using chip integrated Sagnac interferometers with small sensor areas. Here, we address this issue and present a method to improve the sensitivity at a small scale. Therefore, we utilize twomode squeezed light that can be generated in a ring resonator via four-wave mixing (FWM), which can have a very low noise. We show that the combination of classical coherent light and squeezed light can improve the sensor performance compared to a classical fiber optic Sagnac interferometer. For this purpose, we discuss two different configurations that are suited for various applications. The first one makes use of the low-noise of squeezed light and is suited for small and low loss systems using intensitiy difference (ID) measurements while the second one measures the variance of squeezed light via product detection (PD) and is suited for larger and lossy systems.

Zusammenfassung

Microstructuring techniques, such as laser direct writing, enable the integration of microstructures into conventional polymer lens systems and may be used to generate advanced functionality. Hybrid polymer lenses combining multiple functions such as diffraction and refraction in a single component become possible. In this paper, a process chain to enable encapsulated and aligned optical systems with advanced functionality in a cost-efficient way is presented. Within a surface diameter of 30 mm, diffractive optical microstructures are integrated in an optical system based on two conventional polymer lenses. To ensure precise alignment between the lens surfaces and the microstructure, resist-coated ultra-precision-turned brass substrates are structured via laser direct writing, and the resulting master structures with a height of less than 0.002 mm are replicated into metallic nickel plates via electroforming. The functionality of the lens system is demonstrated through the production of a zero refractive element. This approach provides a cost-efficient and highly accurate method for producing complicated optical systems with integrated alignment and advanced functionality.

Zusammenfassung

Increasing demands for precision electronics require individual components such as resistors to be specified, as they can be the limiting factor within a circuit. To specify quality and long-term stability of resistors, noise measurements are a common method. This review briefly explains the theoretical background, introduces the noise index and provides an insight on how this index can be compared to other existing parameters. It then focuses on the different methods to measure excess noise in resistors. The respective advantages and disadvantages are pointed out in order to simplify the decision of which setup is suitable for a particular application. Each method is analyzed based on the integration of the device under test, components used, shielding considerations and signal processing. Furthermore, our results on the excess noise of resistors and resistor networks are presented using two different setups, one for very low noise measurements down to 20 µHz and one for broadband up to 100 kHz. The obtained data from these measurements are then compared to published data. Finally, first measurements on commercial strain gauges and inkjet-printed strain gauges are presented that show an additional 1/fα component compared to commercial resistors and resistor networks.

Zusammenfassung

This work is motivated by the rarely available material data for thermosets and a missing inline viscosity measurement method to monitor melt property deviations. A nozzle viscometer is designed for inline viscosity measurement of phenol-formaldehyde compounds. The nozzle viscometer is mounted at the plasticizing unit of an injection molding machine. A fluid coolant circuit allows a dynamic tempering to pause the transient crosslinking reaction. A 2D FDM model is implemented, to calculate the viscous heating within an injection cycle and to compensate the temperature rising effect in the viscosity measurement. The FDM model processes the inline sensor signals in a closed loop correction in real time to determine a corrected reactive viscosity model. The signal-to-noise-ratio quantifies the reliability of the inline viscosity measurement method.

Zusammenfassung

LDS-MIDs (laser direct structured mechatronic integrated devices) are 3D (three-dimensional) circuit carriers that are used in many applications with a focus on antennas. However, thanks to the rising frequencies of HF (high-frequency) systems in 5G and radar applications up to the mmWave (millimeter wave) region, the requirements regarding the geometrical accuracy and minimal wall thicknesses for proper signal propagation in mmWave circuits became more strict. Additionally, interest in combining those with 3D microstructures like trenches or bumps for optimizing transmission lines and subsequent mounting processes is rising. The change from IM (injection molding) to ICM (injection compression molding) could offer a solution for improving the 3D geometries of LDS-MIDs. To enhance the scientific insight into this process variant, this paper reports on the manufacturing of LDS-MIDs for mmWave applications. Measurements of the warpage, homogeneity of local wall thicknesses, and replication accuracy of different trenches and bumps for mounting purposes are presented. Additionally, the effect of a change in the manufacturing process from IM to ICM regarding the dielectric properties of the used thermoplastics is reported as well as the influence of ICM on the properties of LDS metallization&mdash;in particular the metallization roughness and adhesion strength. This paper is then concluded by reporting on the HF performance of CPWs (coplanar waveguides) on LDS-MIDs in comparison to an HF-PCB.

Zusammenfassung

Mechatronic Integrated Devices or Molded Interconnect Devices (MID) are three-dimensional (3D) circuit carriers. They are mainly fabricated by laser direct structuring (LDS) and subsequent electroless copper plating of an injection molded 3D substrate. Such LDS-MID are used in many applications today, especially antennas. However, in high frequency (HF) systems in 5G and radar applications, the demand on 3D circuit carriers and antennas increases. Electroless copper, widely used in MID, has significantly lower electrical conductivity compared to pure copper. Its lower conductivity increases electrical loss, especially at higher frequencies, where signal budget is critical. Heat treatment of electroless copper deposits can improve their conductivity and adhesion to the 3D substrates. This paper investigates the effects induced by tempering processes on the metallization of LDS-MID substrates. As a reference, HF Printed Circuit Boards (PCB) substrates are also considered. Adhesion strength and conductivity measurements, as well as permittivity and loss angle measurements up to 1 GHz, were carried out before and after tempering processes. The main influencing factors on the tempering results were found to be tempering temperature, atmosphere, and time. Process parameters like the heating rate or applied surface finishes had only a minor impact on the results. It was found that tempering LDS-MID substrates can improve the copper adhesion and lower their electrical resistance significantly, especially for plastics with a high melting temperature. Both improvements could improve the reliability of LDS-MID, especially in high frequency applications. Firstly, because increased copper adhesion can prevent delamination and, secondly, because the lowered electrical resistance indicates, in accordance with the available literature, a more ductile copper metallization and thus a lower risk of microcracks.

Zusammenfassung

A new methodology for considering thermo-mechanical material property variability in virtual design of experiment (vDoE) studies is presented. For the estimation of the lower and upper bounds of the properties, theoretical models and relevant correlations between material properties are presented. The focus for the bounds definition is given to composite materials, i.e., a mixture of two or more homogeneous dissimilar materials, such as metal matrix composites (MMCs), ceramic matrix composites (CMC), etc. For not composite materials, alternative approaches for defining the bounds are discussed. To exemplify the implementation of the proposed methodology, a vDoE of a 2-D finite element (FE) thermo-mechanical model of an electronic package is presented, followed by a discussion regarding the influence of material property variability on the model’s thermo-mechanical responses.

Zusammenfassung

Thermosonic wire bonding is a well-established process. However, when working on advanced substrate materials and the associated required metallization processes to realize innovative applications, multiple factors impede the straightforward utilization of the known process. Most prominently, the surface roughness was investigated regarding bond quality in the past. The practical application of wire bonding on difficult-to-bond substrates showed inhomogeneous results regarding this quality characteristic. This study describes investigations on the correlation among the surface roughness, profile peak density and bonding quality of Au wire bonds on thermoplastic and thermoset-based substrates used for high-frequency (HF) applications and other high-end applications. FR4 PCB (printed circuit board flame resitant class 4) were used as references and compared to HF-PCBs based on thermoset substrates with glass fabric and ceramic filler as well as technical thermoplastic materials qualified for laser direct structuring (LDS), namely LCP (liquid crystal polymer), PEEK (polyether ether ketone) and PTFE (polytetrafluoroethylene). These LDS materials for HF applications were metallized using autocatalytic metal deposition to enable three-dimensional structuring, eventually. For that purpose, bond parameters were investigated on the mentioned test substrates and compared with state-of-the-art wire bonding on FR4 substrates as used for HF applications. Due to the challenges of the limited thermal conductivity and softening of such materials under thermal load, the surface temperatures were matched up by thermography and the adaptation of thermal input. Pull tests were carried out to determine the bond quality with regard to surface roughness. Furthermore, strategies to increase reliability by the stitch-on-ball method were successfully applied.

Zusammenfassung

The use of focused ion and focused electron beam (FIB/FEB) technology permits the fabrication of micro- and nanometer scale geometries. Therefore, FIB/FEB technology is a favorable technique for preparing TEM lamellae, nanocontacts, or nanowires and repairing electronic circuits. This work investigates FIB/FEB technology as a tool for nanotip fabrication and quantum mechanical tunneling applications at a low tunneling voltage. Using a gas injection system (GIS), the Ga-FIB and FEB technology allows both additive and subtractive fabrication of arbitrary structures. Using energy dispersive X-ray spectroscopy (EDX), resistance measurement (RM), and scanning tunneling microscope (STM)/spectroscopy (STS) methods, the tunneling suitability of the utilized metal&ndash;organic material&ndash;platinum carbon (PtC) is investigated. Thus, to create electrode tips with radii down to 15 nm, a stable and reproducible process has to be developed. The metal&ndash;organic microstructure analysis shows suitable FIB parameters for the tunneling effect at high aperture currents (260 pA, 30 kV). These are required to ensure the suitability of the electrodes for the tunneling effect by an increased platinum content (EDX), a low resistivity (RM), and a small band gap (STM). The STM application allows the imaging of highly oriented pyrolytic graphite (HOPG) layers and demonstrates the tunneling suitability of PtC electrodes based on high FIB aperture currents and a low tunneling voltage.

Zusammenfassung

In micro-electro-mechanical systems (MEMS) testing high overall precision and reliability are essential. Due to the additional requirement of runtime efficiency, machine learning methods have been investigated in recent years. However, these methods are often associated with inherent challenges concerning uncertainty quantification and guarantees of reliability. The goal of this paper is therefore to present a new machine learning approach in MEMS testing based on Bayesian inference to determine whether the estimation is trustworthy. The overall predictive performance as well as the uncertainty quantification are evaluated with four methods: Bayesian neural network, mixture density network, probabilistic Bayesian neural network and BayesFlow. They are investigated under the variation in training set size, different additive noise levels, and an out-of-distribution condition, namely the variation in the damping factor of the MEMS device. Furthermore, epistemic and aleatoric uncertainties are evaluated and discussed to encourage thorough inspection of models before deployment striving for reliable and efficient parameter estimation during final module testing of MEMS devices. BayesFlow consistently outperformed the other methods in terms of the predictive performance. As the probabilistic Bayesian neural network enables the distinction between epistemic and aleatoric uncertainty, their share of the total uncertainty has been intensively studied.

Zusammenfassung

Micro-electro-mechanical systems (MEMS) are of great importance in a broad range of applications including vehicle safety and consumer electronics. During the testing of these devices, large heterogeneous data sets containing a variety of parameters are recorded. Aiming to substitute costly measurements as well as to gain insight into the relations among the measured parameters, graph neural networks (GNNs) are investigated. Thus, the questions are addressed whether for inference of MEMS final module level test parameters, working on graph structures leads to an improvement of the predictive performance compared to the analysis via standard machine learning approaches on tabular data and how the graph structure and learning algorithm contribute to the overall performance. To evaluate this, in an empirical study different graph representations of the acquired test data were set up. On these, four different state-of-the-art GNN architectures were trained and compared on the task of raw sensitivity prediction for a MEMS gyroscope. Whereas the GNNs performed on par with a light gradient boosting machine, neural network and multivariate adaptive regression splines model used as baseline on the complete data set, in the presence of sparse data, the GNNs outperformed the baseline methods in terms of the overall root-mean-square error (RMSE) and achieved distinct improvement in the maximum error when trained on data with similar sparsity rates as observed during the validation.

Zusammenfassung

Microelectromechanical devices are known to be sensitive to ambient humidity. This is especially true for devices in moisture sensitive plastic packages such as consumer targeted inertial measurement units. Stress and deformation based effects are shown to be a main contributor to humidity related effects such as performance and offset drifts. This paper shows that stress sensing units embedded in the mechanically coupled electronic control circuitry can be utilized to detect and compensate stress based humidity performance drifts of plastic packaged inertial measurement units. Next to the utilized stress sensor cells themselves a compensation approach is presented, that corrects the humidity based scale factor drift of a MEMS angular rate sensor while a humidity load is applied. This is achieved by finding a symbolic compensation function, which predicts the moisture induced scale factor drift, based only on the stress values within the electronic control circuitry, utilizing genetic symbolic regression. It is demonstrated that, using stress sensors, the humidity induced scale factor drift of two different gyroscope core types can be reduced by a factor of 3, which holds true for parts coming from separate assembly lots. 2022-0013

Zusammenfassung

Encapsulated microelectromechanical measurement units are known to be sensitive to ambient humidity conditions, due to various effects caused by moisture diffusing into and out of the plastic packaging components. This paper focuses on investigating the effect that a change of moisture content has on the transient offset behavior of a packaged MEMS sensor by investigating the output signals of several test devices that only differ in their response to deformation of the MEMS core area. This comprises a novel method of experimentally analyzing the transient drift behavior of a MEMS caused by a deformation of the MEMS core area. This approach enables a back calculation of possible deformation shapes of the core area that explain the observed offset drifts in a given package. It was shown that the humidity response of a MEMS sensor is a strongly transient function that is not proportional to the uptake of water and can therefore significantly differ from their humidity performance at or close to a saturated state. Humidity performance tests that take only this state as point of reference for a performance evaluation cannot correctly estimate the humidity induced offset drifts. It was also shown that the moisture induced offset drifts can be traced back to a superposition of several deformation fields leading to several stages of the humidity response of MEMS sensors. Based on the example of the test devices it was shown that MEMS cores can be optimized to minimize the response of moisture effects. 2021-0212

Zusammenfassung

Digitally printed conductive structures often need to be electrically connected to batteries, microcontrollers, or other devices. A consensus of industry and research is that such hybrid printed electronics will play a major part in the future of printed electronics. To promote the technology of hybrid printed electronics, surface mount technologies for electronic components using isotropic conductive adhesives (ICAs) and low melting tin bismuth solders on inkjet-printed silver structures on injection molded liquid crystal polymer (LCP) substrates were investigated in this publication. The special needs for inkjet-printed electronics were considered as well as the reliability of assembled surface mounted devices (SMDs) and their failure mechanisms. Connected 0603 and 1206 SMD components achieved a characteristic fatigue life of more than 3500 cycles during thermal cycling at +125 °C/−40 °C and withstood over 1000 h under a damp-heat atmosphere of +85 °C/85% RH. The coefficient of thermal expansion (CTE) of the substrate and the selection of solder have major impacts on the reliability of the assemblies.

Zusammenfassung

This paper describes the characterization of inkjet-printed resistive temperature sensors according to the international standard IEC 61928-2. The goal is to evaluate such sensors comprehensively, to identify important manufacturing processes, and to generate data for inkjet-printed temperature sensors according to the mentioned standard for the first time, which will enable future comparisons across different publications. Temperature sensors were printed with a silver nanoparticle ink on injection-molded parts. After printing, the sensors were sintered with different parameters to investigate their influences on the performance. Temperature sensors were characterized in a temperature range from 10 &deg;C to 85 &deg;C at 60% RH. It turned out that the highest tested sintering temperature of 200 &deg;C, the longest dwell time of 24 h, and a coating with fluoropolymer resulted in the best sensor properties, which are a high temperature coefficient of resistance, low hysteresis, low non-repeatability, and low maximum error. The determined hysteresis, non-repeatability, and maximum error are below 1.4% of the full-scale output (FSO), and the temperature coefficient of resistance is 1.23&ndash;1.31 &times; 10&minus;3 K&minus;1. These results show that inkjet printing is a capable technology for the manufacturing of temperature sensors for applications up to 85 &deg;C, such as lab-on-a-chip devices.

Zusammenfassung

High quality and long product life are two fundamental requirements for all circuit carriers, including molded interconnect devices (MID), to find application in various fields, such as automotive, sensor technology, medical technology, and communication technology. When developing a MID for a certain application, not only the design, but also the choice of material as well as the process parameters need to be carefully considered. A well-established method to evaluate the lifetime of such MID, respective of their conductor tracks, is the thermal shock test, which induces thermomechanical stresses upon cycling. Even though this method has numerous advantages, one major disadvantage is its long testing time, which impedes rapid developments. Addressing this disadvantage, this study focuses on the laser direct structuring of thermoplastic LCP Vectra E840i LDS substrates and the subsequent electroless metallization of the commonly used layer system Cu/Ni/Au to force differences in the conductor tracks&rsquo; structure and composition. Performing standardized thermal shock tests alongside with flexural fatigue tests, using a customized setup, allows comparison of both methods. Moreover, corresponding thermomechanical simulations provide a direct correlation. The flexural fatigue tests induce equivalent or even higher mechanical stresses at a much higher cycling rate, thus drastically shorten the testing time.

Zusammenfassung

The assembly of passive components on flexible electronics is essential for the functionalization of circuits. For this purpose, adhesive bonding technology by isotropic conductive adhesive (ICA) is increasingly used in addition to soldering processes. Nevertheless, a comparative study, especially for bending characterization, is not available. In this paper, soldering and conductive adhesive bonding of 0603 and 0402 components on flexible polyimide substrates is compared using the design of experiments methods (DoE), considering failure for shear strength and bending behavior. Various solder pastes and conductive adhesives are used. Process variation also includes curing and soldering profiles, respectively, amount of adhesive, and final surface metallization. Samples created with conductive adhesive H20E, a large amount of adhesive, and a faster curing profile could achieve the highest shear strength. In the bending characterization using adhesive bonding, samples on immersion silver surface finish withstood more cycles to failure than samples on bare copper surface. In comparison, the samples soldered to bare copper surface finish withstood more cycles to failure than the soldered samples on immersion silver surface finish.

Zusammenfassung

Integrating electrical functionality during additive manufacturing (AM) is a promising new field of application. In this article, different concepts for combining an extrusion-based AM process called 3-D dispensing (3DD) with the embedding of electrical components are developed and compared. Based on criteria, such as resulting surface quality or overall accuracy, the best strategy among six different approaches is identified. To further validate and confirm the choice, long-term reliability tests humidity and thermal shock testing (TST) with a particular focus on the electrical contacts between the printed tracks and the embedded electronic components have been conducted. It was shown that the embedding strategy and the cavity design have no influence on the long-term properties of the printed electrical tracks. Finally, an acceleration sensor is embedded in a 3-D housing to prove real use-case applicability and to show the improvements identified in the previous study.

Zusammenfassung

The influence of parametric nonlinearities on the mode matching of closed-loop operated MEMS gyroscopes is investigated. Accurate resonance tuning of mechanical detection modes is essential for optimal noise suppression in closed-loop resonators. Large deflections of the drive mode lead to a geometric nonlinearity, which induces a phase-dependency in the mode-matching procedure. Those effects are known to amplify signal-to-noise ratio in open-loop vibratory MEMS gyroscopes. Predicted and measured tuning voltages and folded response of a sense mode in a prototype gyroscope are compared. Using simulations, it is shown that the pilottone with a 90° phase can confine the crosstalk of the Coriolis and quadrature channel to the quadrature channel exclusively. When applying a quadrature compensation in the simplified model, nonlinear amplification is prohibited in the output channel even for low gain of the force-to-rebalance loop. Furthermore, it is shown that in a simulation with idealized drive motion and demodulation signals the cross-coupling nonlinearity by itself does not have a major impact on standard noise suppression capabilities. 2021-0232

Zusammenfassung

Todays continuous improvement and advancement in the injection molding process for plastics allow for increasing reliability of the process parameter control, whereas the fluctuations of the material properties still present a great challenge. To compensate for these fluctuations, a nozzle capillary rheometer is developed with the aim to determine the viscosity inline during the injection process in series production applications. An essential part of this work is the signal processing and the definition of a suitable integration boundary to ensure a reliable signal evaluation. In addition, based on mathematical modeling and established correction factors, it is possible to determine the effective viscosity accurately without the need to replace the capillary channel according to the Bagley correction.

Zusammenfassung

Nowadays, digital printing technologies such as inkjet and aerosol jet printing are gaining more importance since they have proven to be suitable for the assembly of complex microsystems. This also applies to medical technology applications like hearing aids where patient-specific solutions are required. However, assembly is more challenging than with conventional printed circuit boards in terms of material compatibility between substrate, interconnect material and printed ink. This paper describes how aerosol jet printing of nano metal inks and subsequent assembly processes are utilized to connect electrical components on 3D substrates fabricated by Digital Light Processing (DLP). Conventional assembly technologies such as soldering and conductive adhesive bonding were investigated and characterized. For this purpose, curing methods and substrate pretreatments for different inks were optimized. Furthermore, the usage of electroless plating on printed metal tracks for improved solderability was investigated. Finally, a 3D ear mold substrate was used to build up a technology demonstrator by means of conductive adhesives.

Zusammenfassung

The development and manufacturing of high-precision micro-mechatronic systems (MMS) is a challenging task, and the high demand for individualized products complicates the engineering design process (EDP) in particular. The established EDP for MMS is not designed for individualized products. This article gives an overview of the challenges (critical factors) in product development and manufacturing of individualized MMS (iMMS), a novel definition of iMMS, and describes a new qualitative methodology in order to tailor an EDP based on use cases, so-called “Tailored EDP-Methodology” (TEDP-Methodology). This TEDP-Methodology allows creating use-case-based product groups through the abstraction of the use cases and evaluating the requirements, which is essential to tailor or develop a new EDP. For the development of this new approach, a literature review and qualitative content analysis are prefaced. The TEDP-Methodology is critically examined and validated with a real case study for the development and manufacturing of an iMMS. This study shows critical points within the EDP. It shows fields of action for innovative tools to support the development process of iMMS and requirements for different product groups within iMMS. This article has both theoretical and practical implications.

Zusammenfassung

Most accelerometers today are based on the capacitive principle. However, further miniaturization for micro integration of those sensors leads to a poorer signal-to-noise ratio due to a small total area of the capacitor plates. Thus, other transducer principles should be taken into account to develop smaller sensors. This paper presents the development and realization of a miniaturized accelerometer based on the tunneling effect, whereas its highly sensitive effect regarding the tunneling distance is used to detect small deflections in the range of sub-nm. The spring-mass-system is manufactured by a surface micro-machining foundry process. The area of the shown polysilicon (PolySi) sensor structures has a size smaller than 100 µm × 50 µm (L × W). The tunneling electrodes are placed and patterned by a focused ion beam (FIB) and gas injection system (GIS) with MeCpPtMe3 as a precursor. A dual-beam system enables maximum flexibility for post-processing of the spring-mass-system and patterning of sharp tips with radii in the range of a few nm and initial distances between the electrodes of about 30–300 nm. The use of metal–organic precursor material platinum carbon (PtC) limits the tunneling currents to about 150 pA due to the high inherent resistance. The measuring range is set to 20 g. The sensitivity of the sensor signal, which depends exponentially on the electrode distance due to the tunneling effect, ranges from 0.4 pA/g at 0 g in the sensor operational point up to 20.9 pA/g at 20 g. The acceleration-equivalent thermal noise amplitude is calculated to be 2.4–3.4 mg/Hz. Electrostatic actuators are used to lead the electrodes in distances where direct quantum tunneling occurs.

Zusammenfassung

To realize quantum tunneling applications with movable electrodes, sharp tips with radii down to several tens of nanometers are necessary. The use of a focused ion beam (FIB) and focused electron beam (FEB) with a gas injection system (GIS) allows the integration of geometries in the nanoscale directly into micro and nano systems. However, the implementation of the tunneling effect clearly depends on the material. In this work, a metal-organic precursor is used. The investigation of the prepared tunneling electrodes enables an insight into FIB/FEB parameters for the realization of quantum tunneling applications. For this purpose, a high-resolution transmission electron microscopy (HRTEM) analysis is performed. The results show a dependence of the material nanostructure regarding platinum (Pt) grain size and distribution in an amorphous carbon matrix from the used beam and the FIB currents. The integration of the tips into a polysilicon (PolySi) beam and measuring the current signal by approaching the tips show significant differences in the results. Moreover, the approach of FEB tips shows a non-contact behavior even when the tips are squeezed together. The contact behavior depends on the grain size, proportion of platinum, and the amount of amorphous carbon in the microstructure, especially at the edge area of the tips. This study shows significant differences in the nanostructure between FIB and FEB tips, particularly for the FIB tips: The higher the ion current, the greater the platinum content, the finer the grain size, and the higher the probability of a tunneling current by approaching the tips.

Zusammenfassung

Electronic devices and their associated sensors are exposed to increasing mechanical, thermal and chemical stress in modern applications. In many areas of application, the electronics are completely encapsulated with thermosets in a single process step using injection molding technology, especially with epoxy molding compounds (EMC). The implementation of the connection of complete systems for electrical access through a thermoset encapsulation is of particular importance. In practice, metal pin contacts are used for this purpose, which are encapsulated together with the complete system in a single injection molding process step. However, this procedure contains challenges because the interface between the metallic pins and the plastic represents a weak point for reliability. In order to investigate the reliability of the interface, in this study, metallic pin contacts made of copper-nickel-tin alloy (CuNiSn) and bronze (CuSn6) are encapsulated with standard EMC materials. The metal surfaces made of CuNiSn are further coated with silver (Ag) and tin (Sn). An injection molding tool to produce test specimens is designed and manufactured according to the design rules of EMC processing. The reliability of the metal-plastic interfaces are investigated by means of shear and leak tests. The results of the investigations show that the reliability of the metal-plastic joints can be increased by using different material combinations.

Zusammenfassung

Parameter extraction during the final test of MEMS sensors poses a highly time-critical challenge. The progressing miniaturization, test stimuli and structural complexity lead to nonlinear couplings and inhomogeneity in system differential equations, which cannot be linearized and are therefore dependent on either slow numerical solution methods or machine learning algorithms requiring many labeled data. A transfer learning approach is presented making use of high complexity ASIC-MEMS models for Monte-Carlo generation of simulated devices, which are used to pre-train neural networks on the task of parameter extraction. In a first step, it is shown that for both, high quality factor and low quality factor systems, neural networks are not only able to fit the relation between time-series recorded during final testing and the two performance parameters natural frequency and damping factor but also to extract Brownian noise, mass, and epitaxial layer thickness. Subsequently, it is shown that the transfer learning approach is particularly useful for the determination of parameters, which cannot be measured directly during the final test and for which it is expensive to record labeled data like Brownian noise for systems in a harsh production test environment. If only very few labeled samples are available - in the performed experiments, 25 devices under test were sufficient - the transfer learning approach outperforms a neural network purely trained on measured data. These findings emphasize the practical advances of the transfer learning approach and motivate the evaluation of further applications in the field of parameter extraction in MEMS sensors.

Zusammenfassung

Miniaturization efforts and increasing demands regarding reliability of mechatronic systems require new materials and processes for the 3D mechatronic integrated devices (3D-MID) technology. Currently, in the area of 3D-MID mostly thermoplastic materials are in use in the industry, which are metallized using the LPKF-LDS® process. This paper is supposed to demonstrate the eligibility of thermoset resins as a new material class for 3D-MID applications and as a packaging option for silicon chips which are currently encapsulated using transfer molding of thermosets. The reliability of the conductor tracks made using a LDS-additive free process as well as the adhesion forces are investigated. Different laser parameters for structuring of two different substrate materials are compared. For reliability testing a thermal shock test is applied. Furthermore, the adhesion is tested using Hot-Pin-Pull testing. The conductor tracks surpass 2000 cycles thermo-mechanical load without showing strong deterioration of the track resistivity. The incorporated approach enables electrically reliable functionalization of packaged dummy chips including vias for connection to terminals on the chips. The results of the tested injection moldable thermoset resins are comparable to state-of-the-art 3D-MID thermoplastic substrates and thus, suited as circuit carrier material in electronic packaging.

Zusammenfassung

This work presents an embedding process for ultrathin silicon chips in mechanically flexible solder mask resist and their electrical contacting by inkjet printing. Photosensitive solder mask resist is applied by conformal spray coating onto epoxy bonded ultrathin chips with a daisy chain layout. The contact pads are opened by photolithography using UV direct light exposure. Circular and rectangular openings of 90 µm and 130 µm diameter, respectively, edge length are realized. Commercial inks containing nanoparticular silver and gold are inkjet printed to form conductive tracks between daisy chain structures. Different numbers of ink layers are applied. The track resistances are characterized by needle probing. Silver ink shows low resistances only for multiple layers and 90 µm openings, while gold ink exhibits low resistances in the single-digit Ω-range for minimum two printed layers.

Zusammenfassung

Elektronische Baugruppen werden in der Industrietechnik oder der Kraftfahrzeugtechnik häufig unter rauen Umgebungsbedingungen betrieben und müssen daher vor Umwelteinflüssen geschützt werden. Duroplastverkapselung elektronischer Baugruppen bietet eine Alternative zum metallischen Gehäuse.

Zusammenfassung

The trend of electrification and miniaturization brings the reliability of interconnects to the forefront. The solder joints are subjected to thermo-mechanical mismatch due to the Joule heating and electromigration (EM)-induced degradation under high current stressing conditions. However, most of the studies are limited to lab test samples or lab test conditions, which lack transferability in engineering applications. In this paper, automotive electronic components are studied subjected to field-like current pulse conditions. The work aims to understand the field-relevant failure modes of solder joints exposed to high current stressing via experimental and numerical investigations. Shunt components with and without Ni plating are analyzed in power cycling tests. A polarity effect is observed in the growth of intermetallic compounds (IMCs). The thickness of IMC at the anode exhibits an approximately linear growth with current stressing time, whereas the thickness of IMC at the cathode remains almost unchanged or slightly decreased. Ni, as diffusion barrier, serves to restrain Cu consumption from the terminals of shunts and also reduces Cu mass transport into and within the solder. The net Cu flux at the interface and in the solder is discussed to analyze the IMC growth kinetics. The shunts with Ni plating undergo less EM of Cu and yield longer lifetime. Voids and crack formation are detected in computer tomography (CT) scans and cross-sectional analysis by scanning electron microscopy (SEM). Finite element method (FEM) is implemented to simulate thermo-electro-mechanical fields of the assembly under power cycling test conditions. The distribution of divergence of material flux density corresponds well with the location of voids formation and provides good estimation for the lifetime.

Zusammenfassung

Flexible electronics is a rapidly growing technology for a multitude of applications. Wearables and flexible displays are some application examples. Various technologies and processes are used to produce flexible electronics. An important aspect to be considered when developing these systems is their reliability, especially with regard to repeated bending. In this paper, the frequently used methods for investigating the bending reliability of flexible electronics are presented. This is done to provide an overview of the types of tests that can be performed to investigate the bending reliability. Furthermore, it is shown which devices are developed and optimized to gain more knowledge about the behavior of flexible systems under bending. Both static and dynamic bending test methods are presented.

Zusammenfassung

System-in-foil technology continues to realize relevance in industry and research. In this article, a digital process chain for the fabrication of bend-sensitive sensor structures on a flexible polyimide foil is described. This means that none of the steps in this process chain requires the manufacturing of a structured mask or cliché. Therefore, an arbitrary layout can be manufactured and easily be changed without major effort. Patterning of the sensor layout is realized by direct imaging of a laminated dry film photoresist. The sensor structure is fabricated by a liftoff process using sputtering of a NiCr layer. Finally, the sensor structures are characterized by a static bending test.

Zusammenfassung

In this study, a 3-D dispensing method for nonconductive and conductive adhesives is introduced that allows for direct electrical functionalization of the printed part during the printing process. The experimental work's focus lies on the analysis of the embedding of conductive tracks within nonconductive housings. Two different construction strategies have been analyzed for printing tracks in both xy- and z-directions. For all variants, initial feasibility tests were performed that successfully validated the general applicability of these techniques. As dissimilar materials are involved in the process, a micrograph analysis was used to investigate possible negative effects within the transitional areas. Although prototypical parts can be built easily with additive manufacturing methods, the lack of knowledge about the long-term robustness is often the limiting factor to end-use applications. Accelerated life tests in the form of thermal shock and humidity testing were performed to investigate this issue. The tests demonstrate good long-term behavior for two of four adhesives. The obtained results show that the proposed method and process variants are capable of producing electronically functional parts, provided a careful material selection has been performed. Furthermore, several design rules concerning the transitional area could be derived

Zusammenfassung

Essential quality features of pressure sensors are, among other accuracy-related factors, measurement range, operating temperature, and long-term stability. In this work, these features are optimized for a capacitive pressure sensor with a measurement range of 10 bars. The sensor consists of a metal membrane, which is connected to a PCB and a digital capacitive readout. To optimize the performance, different methods for the joining process are studied. Transient liquid phase bonding (TLP bonding), reactive joining, silver sintering, and electric resistance welding are compared by measurements of the characteristic curves and long-term measurements at maximum pressure. A scanning electron microscope (SEM) with energy-dispersive X-ray spectroscopy (EDX) analysis was used to examine the quality of the joints. The evaluation of the characteristic curves shows the smallest measurement errors for TLP bonding and sintering. For welding and sintering, no statistically significant long-term drift was measured. In terms of equipment costs, reactive joining and sintering are most favorable. With low material costs and short process times, electric resistance welding offers ideal conditions for mass production.

Zusammenfassung

In this paper, a fluidic capacitive inclination sensor is presented and compared to three types of silicon-based microelectromechanical system (MEMS) accelerometers. MEMS accelerometers are commonly used for tilt measurement. They can only be manufactured by large companies with clean-room technology due to the high requirements during assembly. In contrast, the fluidic sensor can be produced by small- and medium-sized enterprises (SMEs) as well, since only surface mount technologies (SMT) are required. Three different variants of the fluidic sensor were investigated. Two variants using stacked printed circuit boards (PCBs) and one variant with 3D-molded interconnect devices (MIDs) to form the sensor element are presented. Allan deviation, non-repeatability, hysteresis, and offset temperature stability were measured to compare the sensors. Within the fluidic sensors, the PCB variant with two sensor cavities performed best regarding all the measurement results except non-repeatability. Regarding bias stability, white noise, which was determined from the Allan deviation, and hysteresis, the fluidic sensors outperformed the MEMS-based sensors. The accelerometer Analog Devices ADXL355 offers slightly better results regarding offset temperature stability and non-repeatability. The MEMS sensors Bosch BMA280 and TDK InvenSense MPU6500 do not match the performance of fluidic sensors in any category. Their advantages are the favorable price and the smaller package. From the investigations, it can be concluded that the fluidic sensor is competitive in the targeted price range, especially for applications with extended requirements regarding bias stability, noise, and hysteresis.

Zusammenfassung

Since the last five decades, polymer-derived ceramics (PDCs) are in use and envisaged for a variety of applications. The transition of a precursor to an inorganic ceramic by pyrolysis and heat-treatment results in either amorphous or nanocrystalline composites with the evolution of phases strongly controlled by the processing conditions. Understanding the deformation behaviour under ambient conditions and at elevated temperatures is key to designing these materials for long-term use. However, quantitative reliable estimation of mechanical properties is quite challenging due to its unique structure which in turn is strongly governed by the precursor chemistry. The mechanical behaviour of PDCs in the form of fibres, bulk and foams are different and they are discussed separately. Both experimental and simulation-based studies are considered in this review. Recently, additive manufacturing processes have been used for the fabrication of PDCs, the mechanical properties of which are also included in this review.

Zusammenfassung

Inkjet-printing of nanoparticle inks allows the integration of electrodes directly into 2.5D structures, like microfluidic chambers. Sensing applications can additionally benefit from the nanoporous morphology of the printed electrodes. The presented results demonstrate that the high effective surface of the porous electrode is suitable for functionalization by immobilizing DNA and determining the DNA density. It is envisioned that the method facilitates the integration of porous electrodes into microfluidic systems.

Zusammenfassung

Bladder tumor recurrence is a serious problem in uro-oncology, as it increases the risk of fatal progression and makes further surgeries necessary. The possibility of intraoperative tissue differentiation can help for diagnostic purposes as well as for ensuring that the entirety of the tumor is removed. The latter not only differ visually from healthy tissue, but also in their mechanical and electrical properties due to an altered physiology. A possible base for intraoperative tissue differentiation are impedance measurements, which are, however, difficult to obtain passing through the limited space of the urethra. This work presents a comparative study of two impedance sensors, which are obtained by laser direct structuring and rely on a four terminal measurement. The miniaturized sensors are suitable for minimally invasive usage. Circular electrodes are placed in a square for a first sensor, whereas a novel combination of one circular electrode and three concentric rings is designed for the second sensor. For each sensor, the specific geometry factor is determined and the impact of sensitivity towards small conductivity changes inside the tissue investigated. Furthermore, multiple ex vivo measurements on fresh pig bladders are carried out with each sensor. It is shown that both sensors reliably determine tissue impedance data that fit empirical tissue models. Conductivity values close to listed data of human urinary bladder are obtained. Ultimately, the novel ring sensor configuration turns out more favorable in terms of sensitivity distribution and yields more reproducible results than the square electrode arrangement.

Zusammenfassung

The production of injection-molding prototypes, e.g., molded interconnect devices (MID) prototypes, can be costly and time-consuming due to the process-specific inability to replace durable steel tooling with quicker fabricated aluminum tooling. Instead, additively manufactured soft tooling is a solution for the production of small quantities and prototypes, but producing complex parts with, e.g., undercuts, is avoided due to the necessity of additional soft tooling components. The integration of automated soft slides into soft tooling has not yet been investigated and poses a challenge for the design and endurance of the tooling. The presented study covers the design and injection-molding trial of soft tooling with integrated automated slides for the production of a complex MID prototype. The design further addresses issues like the alignment of the mold components and the sealing of the complex parting plane. The soft tooling was additively manufactured via digital light processing from a silica-filled photopolymer, and 10 proper parts were injection-molded from a laser-direct structurable glass fiber-filled PET+PBT material before the first damage on the tooling occurred. Although improvements are suggested to enhance the soft tooling durability, the designed features worked as intended and are generally transferable to other part geometries.

Zusammenfassung

In order to economize injection molded prototypes, additive manufacturing of, e.g., curable plastics based tools, can be employed, which is known as soft tooling. However, one disadvantage of such tools is that the variothermal process, which is needed to produce polymeric parts with small features, can lead to a shorter lifespan of the tooling due to its thermally impaired material properties. Here, a novel concept is proposed, which allows to locally heat the mold cavity via induction to circumvent the thermal impairment of the tooling material. The developed fabrication process consists of additive manufacturing of the tooling, PVD coating the mold cavity with an adhesion promoting layer and a seed layer, electroplating of a ferromagnetic metal layer, and finally patterning the metal layer via laser ablation to enhance the quality and efficiency of the energy transfer as well as the longevity by geometric measures. This process chain is investigated on 2D test specimens to find suitable fabrication parameters, backed by adhesion tests as well as environmental and induction tests. The results of these investigations serve as proof of concept and form the base for the investigation of such induction layers in actual soft tooling cavities.

Zusammenfassung

In this paper, the usability of the classical Harmonic Balancing method (cHB) to calculate the weakly nonlinear motion of phase- and amplitude controlled MEMS resonators is demonstrated. A polynomial mechanical stiffness description and linearized electrostatic effects are considered, which allow determining the Jacobian analytically. The effects of amplitude and phase control are taken into account by applying boundary conditions in the iteration process. With a customized cHB, it is possible to efficiently simulate the behavior of a MEMS gyroscope undergoing nonlinear resonance with higher parasitic modes. The presented results of a virtual model compare very well with solutions obtained with the Shooting method. Furthermore, we compare the measurement of a drive frequency discontinuity, taken from a different prototype, with the prediction from our linear extrapolated model and from a model with artificially fitted parameters. The cHB approach yields an order of magnitude speed-up in comparison to the transient simulation method. Besides some restrictions, customized cHB methods are interesting candidates for fast system-type simulation considering the MEMS-ASIC interface. 2021-0028

Zusammenfassung

The project &ldquo;key enabling technologies for clean production&rdquo; (KET4CP), which is supported by the European Commission, has the aim to connect small and medium-sized enterprises (SME) and Technology Centres (TC) for cleaner, greener and more efficient production. Within this context, SMEs and TCs across Europe work together to establish an open-innovation network and to raise awareness in productivity and environmental performance. This article presents how an open European network of TCs opens its innovation process to support SMEs to become cleaner, greener and more efficient. Furthermore, this article shows how the TCs and SMEs become a part of the open-eco-innovation platform in clean production and how successful the open-eco-innovation process of different European countries is. We revealed that a pan-European open innovation process for eco-innovations with TCs for key enabling technologies (KET TCs) and Enterprise Europe Network partners (EEN) is a successful approach for SMEs that want to produce and develop cleaner products. An application example is mentioned, in which TCs from different European countries have contributed to developing a product of a SME for energy harvesting. The SME, together with the TCs, developed a generator that is installed in city-level water supply pipes and so, it is outstanding in its application. This innovative application is also described in this article.

Zusammenfassung

The design for the reliability of automotive electronics involving viscoelastic materials requires accurate knowledge of material properties under critical frequency and temperature conditions. Both forward and inverse approaches for the dynamic characterization of a soft silicone-based thermal interface material used in electronic control units are presented and discussed. The classic forward characterization implying dynamic mechanical analysis and the principle of time-temperature superposition is applied in a first step. The identified material model under critical temperature conditions is restrained to a narrow frequency range and a validation for higher frequencies is needed. The proposed inverse method presented in the second part minimizes the residue between the measured and numerical transfer functions of single-lap joint specimens at chosen control frequency ranges located at the resonances of the structure. The specimens are excited by an electrodynamic shaker situated in an environmental chamber allowing measurements under different temperature conditions. The main outcome of the inverse approach is a validation of the results of forward characterization for a broad frequency range and under critical temperature conditions adopting a simple experimental arrangement and a barely complex numerical procedure.

Zusammenfassung

Reconfigurable manufacturing systems (RMS) can be used to produce micro-assembled products that are too complex for assembly on flat substrates like printed circuit boards. The greatest advantage of RMS is their capability to reuse machine parts for different products, which enhances the economical efficiency of quickly changing or highly individualized products. However, often, process engineers struggle to achieve the full potential of RMS due to product designs not being suited for their given system. Guaranteeing a better fit cannot be done by static guidelines because the higher degree of freedom would make them too complex. Therefore, a new method for generating dynamic guidelines is proposed. The method consists of a model, with which designers can create a simplified assembly sequence of their product idea, and another model, with which process engineers can describe the RMS and the procedures and operations that it can offer. By combining both, a list of possible machine configurations for an RMS can be generated as an automated response for a modeled assembly sequence. With the planning tool for micro-assembly, an implementation of this method as a modern web application is shown, which uses a real existent RMS for micro-assembly.

Zusammenfassung

Thermoset materials offer a multitude of advantageous properties in terms of shrinkage and warpage as well as mechanical, thermal and chemical stability compared to thermoplastic materials. Thanks to these properties, thermosets are commonly used to encapsulate electronic components on a 2nd-level packaging prior to assembly by reflow soldering on printed circuits boards or other substrates. Based on the characteristics of thermosets to develop a distinct skin effect due to segregation during the molding process, the surface properties of injection molded thermoset components resemble optical characteristics. Within this study, molding parameters for thermoset components are analyzed in order to optimize the surface quality of injection molded thermoset components. Perspectively, in combination with a reflective coating by e.g., physical vapor deposition, such elements with micro-integrated reflective optical features can be used as optoelectronic components, which can be processed at medium-ranged temperatures up to 230 &deg;C. The obtained results indicate the general feasibility since Ra values of 60 nm and below can be achieved. The main influencing parameters on surface quality were identified as the composition of filler materials and tool temperature.

Zusammenfassung

Hermeticity of an electronic package defines its effectiveness to seal and protect the encapsulated electronics from the ingress of contaminants, gases, and moisture, as well as helping avoid toxic materials from inside the capsule contacting tissue. Using accelerated testing by methods of leak detection analysis, the theoretical limit of the lifetime due to water ingress of an encapsulated device can be estimated. However, classical methods are not sufficient for microencapsulations and exhibit limitations due to the resolution of the detection mechanisms required for such small cavities. With the availability of cumulative helium leak detection (CHLD), the detection limits can be extended by several magnitudes of resolution. However, limitations due to the physics of leakage apply. This article discusses the limitations concerning the ability for combined gross and fine leak testing in combination with outgassing effects using CHLD for miniaturized implantable medical devices. Practical aspects are evaluated regarding the applicability of CHLD for such microencapsulations at the example of an AuSn-sealed alumina package.

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This paper presents a feasibility study of an automated pick-and-place process for ultrathin chips on a standard automatic assembly machine. So far, scientific research about automated assembly of ultrathin chips, with thicknesses less than 50 &micro;m, is missing, but is necessary for cost-effective, high-quantity production of system-in-foil for applications in narrow spaces or flexible smart health systems applied in biomedical applications. Novel pick-and-place tools for ultrathin chip handling were fabricated and a process for chip detachment from thermal release foil was developed. On this basis, an adhesive bonding process for ultrathin chips with 30 &micro;m thickness was developed and transferred to an automatic assembly machine. Multiple ultrathin chips aligned to each other were automatically placed and transferred onto glass and polyimide foil with a relative placement accuracy of &plusmn;25 &micro;m.

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Digital printing technologies, such as inkjet or aerosol jet, are becoming increasingly interesting for the manufacturing of electronic devices. As a maskless and contactless process, it offers the potential for low-cost deposition of functional materials onto flat, flexible, or 3-D substrates. Common inks used for printed electronics are nanoparticle (NP) metal inks. Silver (Ag) is widely used because of its excellent conductivity, but also gold (Au) inks are of interest for several applications. By using NP inks, it is possible to integrate conductive paths and sensors onto temperature-sensitive substrate materials, such as polymers. Polymers often need a pretreatment, such as a plasma treatment for improving the wetting. Plasma treatment usually changes the wetting behavior of the complete substrate surface. This could be critical for some applications, e.g., fluidic applications, where the original properties of the substrate should be kept. Low-pressure plasma as a vacuum process is also difficult for implementation into an existing process. In this article, laser irradiation for local improvement in wetting of an inkjet-printed gold ink on polymer substrates is investigated. The experiments show that laser irradiation is a very promising technique for the modification of polymer surfaces and suitable for inkjet printing NP inks on hydrophobic polymer surfaces. This offers new opportunities for printed electronics, which could be easily integrated into the existing processes.

Zusammenfassung

Mechatronic Integrated Devices (MID) made of thermoplastics (injection-molded circuit carriers) are now state of the art when it comes to applying electronic circuits and sensor technology to components with a complex 3D geometry. The technology has now also been successfully extended to ceramic 3D circuit carriers, which are characterized by improved chemical and thermal resistance and increased thermal conductivity, thus opening up additional fields of application.

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The measurement of the radio frequency reflection coefficient is widely used in characterizing various materials nondestructively. Generally, the measurement is done using a one port vector network analyzer together with some sort of probe. Here, the design theory of a new, low-cost replacement for such a network analyzer is explained. The proposed Cartesian reflection coefficient measurement block is outlined as well as the results of computer simulations and measurements on a printed circuit board (PCB) setup. Unlike previous approaches, it explores the use of injection locking to enhance the performance of quadrature amplitude demodulation of both the forward and the reflected waves as sampled from the output path of an ultrahigh-frequency power amplifier by a bidirectional coupler. Computer simulations at 400 MHz resulted in an average error of 3.4% full scale on the reflection coefficient, including extreme impedance values as well as various parasitic effects of the circuit measurements on a simplified PCB setup, also at 400 MHz.

Zusammenfassung

To date, several photonic applications have been demonstrated without considerable thermal management efforts. However, in phase-sensitive photonic applications, thermal management becomes of utmost importance. Thermal management of photonic systems requires not only efficient heat dissipation, but also reduction of on-chip temperature gradients. Particularly in highly integrated systems, in which several components are integrated within a single photonic integrated circuit, the reduction of on-chip temperature gradients is necessary to guarantee the correct functionality of the system. Due to their high integration density as well as their extreme temperature sensitivity, optical phased arrays are ideal examples of a system, where thermal management is required. Ideally, thermal management solutions of such systems should not require additional power for operation. Therefore, it is desired to improve the heat dissipation and to reduce temperature gradients by structural modifications of the photonic circuit. Furthermore, to cope with the advantages of silicon photonics, thermal management solutions must be compatible with series fabrication processes. In this work, complementary metal&ndash;oxide&ndash;semiconductor (CMOS)-compatible measures for thermal management of silicon photonic integrated circuits are proposed and validated by characterization of in-house fabricated thermal demonstrators. The proposed concepts are extremely efficient not only in reducing temperature gradients, but also in improving the heat dissipation from integrated heat sources.

Zusammenfassung

A fibre orientation dependent material model of the thermoset is implemented to predict the lifetime of electronic components as a part of 2nd level encapsulated packages. Experimental data are used in combination with coupled simulations (process simulation – fibre orientation dependant material model – thermo-mechanical simulation) for defining this lifetime prediction model. An already existing lifetime prediction model based on the Coffin-Manson relation is used initially to evaluate the prediction accuracy. The prediction model is then adjusted and fitted for the current application.

Zusammenfassung

A drastically growing requirement of electronic packages with an increasing level of complexity poses newer challenges for the competitive manufacturing industry. Coupled with harsher operating conditions, these challenges affirm the need for encapsulated board-level (2nd level) packages. To reduce thermo-mechanical loads induced on the electronic components during operating cycles, a conformal type of encapsulation is gaining preference over conventional glob-tops or resin casting types. The availability of technology, the ease of automation, and the uncomplicated storage of raw material intensifies the implementation of thermoset injection molding for the encapsulation process of board-level packages. Reliability case studies of such encapsulated electronic components as a part of board-level packages become, thereupon, necessary. This paper presents the reliability study of exemplary electronic components, surface-mounted on printed circuit boards (PCBs), encapsulated by the means of thermoset injection molding, and subjected to cyclic thermal loading. The characteristic lifetime of the electronic components is statistically calculated after assessing the probability plots and presented consequently. A few points of conclusion are summarized, and the future scope is discussed at the end.

Zusammenfassung

We investigate the influence of parametric excitations on MEMS vibration energy harvesters for energy autonomous sensor systems. In Industry 4.0 (or Industrial IoT) applications, interconnected sensors provide a means of data acquisition for automated control of the manufacturing process. Ensuring a continuous energy supply to the sensors is essential for their reliable operation. Manufacturing machines usually display a wide spectrum of vibration frequencies which needs to be covered by an array of harvester substructures in order to maintain the desired output level. We show that mechanical structures designed to implement a Helmholtz-Duffing oscillator have an increased bandwidth by exploiting several orders of parametric resonances. In contrast to concepts implementing parametric amplification in a multi-mode scenario, our concept is based on a single mechanical mode. Therefore, it is more robust against fabrication tolerances as the relevant multi-mode resonance conditions do not need to be matched on the level of single chips. Using exact transient simulations and semi-analytic models to showcase the relation of the Helmholtz-Duffing oscillator to the damped and driven Mathieu equation, we show that parametric resonances highly increase the bandwidth of the output power whenever high Helmholtz nonlinearities are present. To achieve the required nonlinearities, we suggest nonlinear stress-strain curves and we propose to achieve such nonlinearities through field-induced striction by magneto- or electrostriction. In contrast to existing approaches, where external fields are harvested using strictive effects, we employ external fields that manipulate the effective Young’s modulus to achieve parametric excitations in a mechanical oscillator. Thus, we are able to propose a novel energy harvester concept incorporating strictive materials that exploits the effects of parametric excitations to achieve broadband vibrational energy harvesting.

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In this study slip cast alumina-zirconia materials were doped with nickel oxide and chromium oxide and sintered in air. Chromium oxide forms a solid solution while nickel oxide forms spinel with alumina. The sintered substrates were selectively irradiated with a green, ps pulsed Nd:YVO4 laser. During subsequent autocatalytic plating, copper was deposited selectively on laser-irradiated surfaces. It is assumed that under the irradiation influence at very high temperatures metal or lower valence oxides are produced which initiate the growth of copper crystallites during the plating process. The process offers the opportunity to manufacture 3D integrated circuit carriers with ceramic substrates, which offer superior strength, thermal stability and heat conductivity compared to polymers. Single dopant or co-dopant contents of < 2 wt% are sufficient to induce a reliable laser activation at a broad range of laser parameters which enables the application of very narrow continuous conductor paths.

Zusammenfassung

We demonstrate mass production compatible fabrication of polymer-based micro Fresnel lenses by injection compression molding. The extremely robust titanium-molding tool is structured with high precision by focused ion beam milling. In order to achieve optimal shape accuracy in the titanium we use an iterative design optimization. The inverse Fresnel lens structured into the titanium is transferred to polymers by injection compression molding, enabling rapid mass replication. We show that the optical performance of the molded diffractive Fresnel lenses is in good agreement with simulations, rendering our approach suitable for applications that require compact and high-quality optical elements in large numbers.

Zusammenfassung

The use of 3D printing technologies enhanced with component placement and electrical interconnect deposition enables electronic systems with freedom in fabrication and complex embedded circuitry. However, with more electrical functionality being integrated, new material requirements become increasingly important. Well-established adhesive systems in electronic packaging have the potential to fulfill these requirements. This paper introduces a novel approach for processing adhesives with an extrusion-based UV-assisted 3D dispensing process. A specimen study revealed promising results for three out of six adhesives (denoted as A, D, E), for which an extensive anisotropy evaluation was performed: The relationship between the layered construction strategy and the material properties of the printed parts was characterized by micrograph analysis, tensile testing along with fracture analysis and laser flash analysis. An exemplary study for one adhesive via tensile testing showed no significant difference between three printing orientations. However, different construction strategies influenced the degree of anisotropy. The epoxy/acrylate (A) and polycarbamin system (D) showed higher strength and strain values when printed horizontally, indicating that the adhesive strength between the layers was not sufficient. The interlayer bonding for the epoxy system (E) was better due to the crosslinking between the layers. In addition, the evaluation of thermal anisotropy revealed a link between the thermal conductivity and the rate of the UV-curing for A and D. For material E, no significant difference was measured. The work presented in this article shows that dual-curing adhesives, in particular epoxy systems, are promising choices for additive manufacturing: It was possible to print fine geometries with good material properties and low anisotropy. These results are appealing since a wide variety of different adhesive systems is available. The findings serve to derive first design rules and provide a basis for further studies.

Zusammenfassung

Inkjet technology as a maskless, direct-writing technology offers the potential for structured deposition of functional materials for the realization of electrodes for, e.g., sensing applications. In this work, electrodes were realized by inkjet-printing of commercial nanoparticle gold ink on planar substrates and, for the first time, onto the 2.5D surfaces of a 0.5 mm-deep microfluidic chamber produced in cyclic olefin copolymer (COC). The challenges of a poor wetting behavior and a low process temperature of the COC used were solved by a pretreatment with oxygen plasma and the combination of thermal (130 &deg;C for 1 h) and photonic (955 mJ/cm&sup2;) steps for sintering. By performing the photonic curing, the resistance could be reduced by about 50% to 22.7 &micro;Ω cm. The printed gold structures were mechanically stable (optimal cross-cut value) and porous (roughness factors between 8.6 and 24.4 for 3 and 9 inkjet-printed layers, respectively). Thiolated DNA probes were immobilized throughout the porous structure without the necessity of a surface activation step. Hybridization of labeled DNA probes resulted in specific signals comparable to signals on commercial screen-printed electrodes and could be reproduced after regeneration. The process described may facilitate the integration of electrodes in 2.5D lab-on-a-chip systems.

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Traceability of single parts is essential in automated manufacturing, especially considering recent developments in Industry 4.0 or Smart Manufacturing. In some cases, however, conventional traceability methods, e.g. barcode, DMC or RFID, are not sufficient to track individual components through their entire production chain. One solution is the exploitation of an object’s inherent, individual surface patterns. This work demonstrates label-/tag-free traceability of approx. 1000 components in a molded interconnect device (MID) production chain. The parts’ surface patterns are photographed several times along the MID production chain. Based on the captured images nearly 3300 successful identification processes were performed without any failure. Using a hash algorithm to compress the relevant data of the surface pattern images reduces the required disk space and the runtime significantly. Since the results demonstrate the robustness against surface alterations, this work gives the proof of concept regarding to a method for fast label-/tag-free part tracking that is applicable in an industrial production line.

Zusammenfassung

Silicon photonic optical phased arrays leveraging from the well established CMOS fabrication process have become promising candidates to realize miniaturized beam steering systems. While different implementations of optical phased arrays have been successfully demonstrated, no investigations on the influence of thermal distortions on the response of these systems have been performed so far. Due to the high thermo-optic coefficient of silicon, the refractive index and thus the functionality of silicon photonic components depend strongly on the temperature. In highly integrated systems, consisting of several photonic components, in which laser sources and control electronics are directly integrated on top of the photonic IC, heat dissipated by active components leads to temperature gradients and offsets, affecting the functionality of the photonic system. Optical phased arrays consisting of an array of phase sensitive components, are particularly sensitive towards temperature. Therefore, precise investigations of the temperature dependence of the OPA functionality are required. This article aims to expand the understanding of the influence of thermal distortions on the steering angles of optical phased arrays. Thereto, analytical expressions describing the temperature dependence of the steering angles are provided and experimentally validated. The expressions are provided in a general form so that they can be applied to any OPA system regardless of its implementation.

Zusammenfassung

A newly developed laser-assisted process is presented, by which a selective additive metallization of injection-molded alumina ceramic substrates without additional additives is enabled. Alumina substrates were manufactured by ceramic injection molding (CIM) with subsequent debinding and sintering. The substrate surfaces are activated by laser patterning for subsequent electroless plating of the activated areas with copper, nickel, and gold. Three-dimensionally shaped ceramic interconnect devices are enabled by CIM combined with 3-D laser patterning. The conducting paths fabricated in this way are characterized and compared to conducting paths made by a laser-direct-structure technology on thermoplastics developed by the company LPKF Laser & Electronics AG (LPKF-laser direct structuring process). The obtained metal layer thickness with about 10 μm is similar to metal layer thickness on thermoplastic substrates. Obtained metal surface roughness on ceramic substrates of below 10 μm is even lower than on thermoplastics. The high adhesion of approximately 30 N mm −2 combined with the low thermal expansion coefficient of the alumina substrate promises good reliability even under thermal load.

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Faster product lifecycles make long-term investments in machines for micro assembly riskier. Therefore, reconfigurable manufacturing systems gain more and more attention. But most companies are uncertain if a reconfigurable manufacturing system can fulfill their needs and justify the initial investment. New and improved techniques for product development have the potential to foster the utilization and decrease the investment risk for such systems. In this paper, four different methods for product development are reviewed. A set of criteria regarding micro assembly on reconfigurable manufacturing systems RMS is established. Based on those criteria and the assessment, a novel approach for a product development method is provided, which tries to combine the strengths of the beforehand presented approaches. It focuses on the conceptual design phase to overcome the customers&rsquo; uncertainty in the development process. For this, an abstract representation of a micro-assembly product idea as well as a decision tree for joining processes are established and validated by real product ideas using expert interviews. The validation shows that the conceptual design phase can be used as a useful tool in the product development process in the field of micro assembly.

Zusammenfassung

This article presents a simple approach for high-accuracy assembly of multiple ultrathin chips on flexible foil substrates. The chips are placed initially in the cavities on a chip carrier substrate and transferred onto a thermally releasable adhesive tape. After application of the epoxy-based adhesive onto the chip surface, the chips are transferred onto the foil substrate. Finally, the epoxy adhesive is cured and the adhesive tape is removed. It was found that a wafer dicing tape with a releasing temperature of 90 °C as thermally releasable adhesive tape and a two-component epoxy adhesive with a curing temperature of 65 °C is suitable for the process. High placement accuracy of the chips of less than 30 μm in the x- and y-orientation as well as rotational misalignment lower than 0.2° were obtained. The process is demonstrated on a polyimide foil with a resulting chip flatness of ±5 μ

Zusammenfassung

Digital printing technologies are well suited for structured deposition of functional materials such as nanoparticular metal inks on different substrates. Inkjet printing as a maskless and direct writing technology is very suitable for the manufacturing of low-cost devices and packages, e.g., for highly integrated sensor systems. The availability of printable materials is ever expanding and enables new capabilities in many applications. Currently, nanoparticular silver inks are very popular for inkjet printing of conductive paths. However, at present, the availability of reliable technologies for the assembly of electrical components is a challenge. In this paper, the soldering of chip resistors on inkjet-printed silver structures was investigated.

Zusammenfassung

An ever-growing market demand for board (second) level packages (e.g., embedded systems, system-on-a-chip, etc.) poses newer challenges for its manufacturing industry in terms of competitive pricing, higher reliability, and overall dimensions. Such packages are encapsulated for various reasons including thermal management, protection from environmental conditions and dust particles, and enhancing the mechanical stability. In the due course of reducing overall sizes and material saving, an encapsulation as thin as possible imposes its own significance. Such a thin-walled conformal encapsulation serves as an added advantage by reducing the thermo-mechanical stresses occurring due to thermal-cyclic loading, compared to block-sized or thicker encapsulations. This paper assesses the encapsulation process of a board-level package by means of thermoset injection molding. Various aspects reviewed in this paper include the conception of a demonstrator, investigation of the flow simulation of the injection molding process, execution of molding trials with different encapsulation thicknesses, and characterization of the packages. The process shows a high dependence on the substrate properties, injection molding process parameters, device mounting tolerances, and device geometry tolerances. Nevertheless, the thermoset injection molding process is suitable for the encapsulation of board-level packages limiting itself only with respect to the thickness of the encapsulation material, which depends on other external aforementioned factors.

Zusammenfassung

Research based as well as industrialized harvester developments indicate that electrodynamic energy harvesters (EHs) outperform piezoelectric EHs in macroscopic designs for narrow banded resonance-based transducers. This paper investigates how multiple vibration EHs can be combined to a macroscopic array configuration that covers 100–600 Hz by aiming not on high resonance peak powers but on close spectral overlapping in lower power regions of 0.5 mW. The 500 Hz-wide array is able to harvest vibrational energy from a multitude of machinery, independent of vibration frequency determining shaft speeds or flows. The novelty of this paper consists in the result that combining piezoelectric EHs to arrays outperforms electrodynamic arrays with respect to their volumetric power density for 500 Hz-wide operation. Further optimization is reached by introducing nonlinearities for the piezoelectric array. The presented design allows a flat integration of piezoelectric EH-arrays as power supply for energy autonomous sensor systems.

Zusammenfassung

Energy autonomous sensors for I4.0 applications powered by kinetic energy harvesters (KEHs) are widely discussed – especially in terms of vibration harvesting. Typically, industrial linear stages offer weak vibrations, so other inertia-based harvesting methods are investigated. This study investigates the usability of human motion energy harvesters in industrial linear motion technology for the first time. Two KEHs – harvesting swing or shocks, respectively – are tested while controlling the parameters velocity, acceleration, and jerk-limitation according to the real applications’ parameter ranges. The swing-KEH and the shock-KEH harvested up to 106 and 124 mW, respectively. Furthermore, a parameter study is performed assuming constant driving lengths with optimised stroke rates to obtain a generalised power and energy profile for each harvester. The analytically obtained overall average power is 22 mW for the swing-KEH and 14 mW for the shock-KEH. The analytical investigation revealed that a reciprocal dependency of performance and velocity exists for both KEHs, respectively. Both experimental and analytical parts show that the wireless sensor node for I4.0 on industrial linear stages can be powered by harvesters made for human motions.

Zusammenfassung

When electronic assemblies are experiencing high current loading conditions, thermo-mechanical mismatch induced from the local Joule heating of the component and electromigration (EM)-induced void formation can lead to the failure of the solder interconnect. Scanning electron microscopy (SEM) and electron backscatter diffraction (EBSD) are adopted to investigate the microstructural evolution of solder joints of shunt components subjected to current stressing. Voids and micro-cracks initiate at the corner of solder meniscus, where the maximal divergence of material flux density is located on the basis of finite element method (FEM) simulation. The EM-induced voids introduce higher accumulated plastic strain in the solder joints, which will result in reduction in the lifetime of the electronic assemblies.

Zusammenfassung

Electron spins in solids constitute formidable quantum sensors. Individual defect centers in diamond were used to detect individual nuclear spins with nanometer scale resolution, and ensemble magnetometers rival SQUID and vapor cell magnetometers when taking into account room temperature operation and size. NV center spins can also detect electric field vectors, despite their weak coupling to electric fields. Here, we employ ensembles of NV center spins to measure macroscopic ac electric vector fields with high precision. We utilize low strain, 12C enriched diamond to achieve maximum sensitivity and tailor the spin Hamiltonian via proper magnetic field adjustment to map out the ac electric field strength and polarization and arrive at refined electric field coupling constants. For high precision measurements we combine classical lock-in detection with aspects from quantum phase estimation for effective suppression of technical noise. Eventually, this enables t^-1/2 uncertainty scaling of the electric field strength over extended averaging periods, enabling us to measure electric fields down to 10^-7 V/μm for an AC electric field with a frequency of 2 kHz and an amplitude of 0.012 V/µm.

Zusammenfassung

The fabrication of microstructured polymer optics enables a multitude of new options in the design of technical optics. However, challenges arise along the varying process chains of mold insert fabrication, integration into molding tools, replication by means of injection compression molding and metrology. In order to study the effects, diffractive optical elements (DOE) and microlens arrays (MLA) are fabricated using two different process chains. DOEs are fabricated using a laser direct writing (LDW) based mold insert fabrication. The MLA mold insert is produced using ultra-precision milling (UP-milling). Both optical parts are replicated using injection compression molding. The occurring effects are discussed and the results show, that with complete process control high quality microstructured polymer optical parts can be produced and characterized.

Zusammenfassung

In this work, a new process chain for the fabrication of curved micro-structured optical elements by injection compression molding is investigated. The fabrication is demonstrated for the example of a curved diffractive optical element (DOE). In a first process step a master substrate is fabricated using laser direct writing on a curved glass substrate. Blazed diffractive micro-structures with lateral feature sizes down to 5 μm and height of 1.6 μm are created. A subsequent electroplating process is applied to create a nickel stamper to be used as a tool insert for the molding process. During electroplating, a 3 mm nickel layer is formed, transferring the diffractive structures from the master substrate into a solid mold insert. The nickel stamper shows an accurate reproduction of the micro-structures. The mold insert is integrated into an injection compression molding tool to replicate the optical elements. Results show that the blazed diffractive structures are replicated with a high quality. Tests of the components within a chromatic-confocal measurement setup confirm that they can potentially replace expensive conventional elements.

Zusammenfassung

Polymer optics have gained increasing importance in recent years. With advancing requirements for the optical components, the fabrication process remains a challenge. In particular, the fabrication of the mold inserts for the replication process is crucial for obtaining high-quality optical components. This review focuses on fabrication technologies for optical mold inserts. Thereby, two main types of technologies can be distinguished: fabrication methods to create mold inserts with optical surface quality and methods to create optical microstructures. Since optical mold inserts usually require outstanding form accuracies and surface qualities, a focus is placed on these factors. This review aims to give an overview of available methods as well as support the selection process when a fabrication technology is needed for a defined application. Furthermore, references are given to detailed descriptions of each technology if a deeper understanding of the processes is required.

Zusammenfassung

A novel optical incremental and absolute encoder based on an optical application-specific integrated circuit (opto-ASIC) and an encoder disc carrying micro manufactured structures is presented. The physical basis of the encoder is the diffraction of light using a reflective phase grating. The opto-ASIC contains a ring of photodiodes that represents the encryption of the encoder. It also includes the analog signal conditioning, the signal acquisition, and the control of a light source, as well as the digital position processing. The development and fabrication of the opto-ASIC is also described in this work. A laser diode was assembled in the center on top of the opto-ASIC, together with a micro manufactured polymer lens. The latter was fabricated using ultra-precision machining. The encoder disc was fabricated using micro injection molding and contains micro structures forming a blazed grating. This way, a 10-bit optical encoder with a form factor of only 1 cm3 was realized and tested successfully.

Zusammenfassung

Due to many advantages, such as cost-effective production, design freedom, and weight reduction, plastics have replaced metals and ceramics in many fields. However, engineering plastics are good thermal insulators. This characteristic, although beneficial in certain applications, poses many challenges in many heat-generating applications. This can lead to hot spots or even to an increase in the device temperature. Along with the increasing demand for plastics in areas of the lighting technology or in the automotive field due to the free shaping potential, the requirements are becoming more challenging. Driven by the trend of miniaturization, applications with high heat generation often have to operate in the tightest of spaces. Since not always sufficient space for complex cooling systems is given, the housing or the substrate should assume the task of thermal management. In regard to this fact, the use of thermally conductive thermoplastics seems to be very appealing. Quality loss, poorer reliability, loss of performance, and even failure can occur in case of insufficient heat dissipation. In order to improve the properties of these polymers, highly heat-conducting fillers are added in order to improve the thermal conductivity of the compound. Another technology trend that has been prevalent for years is the use of simulations. Due to shorter product life cycles and therefore shorter development times, simulation has become an indispensable part of the chain of product development. Time-consuming and costly test series make the simulation more and more important as a tool for material and product design. In this context, this paper presents a novel approach for reliability investigation and lifetime estimation, based on simulation. Therefore, a simulative method based on coupling the results from the process simulation (injection molding simulation) to finite element analysis was developed and explained. This coupled method makes it possible to take into account the manufacturing process and its engendered filler orientation. The obtained findings are compared to conventional thermal steady-state analysis and used in order to better predict the lifetime of LEDs mounted on thermoplastic substrates, the so-called molded interconnect devices. It is demonstrated that it is necessary to consider the filler orientation, especially in the case of 3D substrates.

Zusammenfassung

As miniaturization is an important aspect in all areas of circuit technology, highest demands are placed on optimum space utilization and the reduction of material and production cost. MID (Molded Interconnect Devices or Mechatronic Integrated Devices) are already broadly used in consumer electronics antennas, automation, automotive and medical technology, however MID have unexploited potential for high-frequency and fast-paced systems in particular. This work will present the design and manufacturing process of MID for RF (Radio Frequency) applications and provide RF relevant characteristics for substrate materials used in the LPKF-LDS (r)(Laser Direct Structuring) process. Furthermore, characteristics of the circuits on the injection molded plastic part, optimization of vias and interconnection geometries for hybrid assemblies will be discussed

Zusammenfassung

Silicon photonics has become a promising technology for fabrication of compact, highly integrated systems. When dealing with phase sensitive silicon photonic components, however, temperature control and in particular, reduction of temperature gradients across phase sensitive components becomes crucial. Solid-state optical beam steering using optical phased arrays (OPAs), is an exemplary system, which could be miniaturized by using silicon photonics and where temperature control is of utmost importance. In order to reduce the system cost and size as well as to increase the steering velocity, it is desired to replace mechanical beam steering systems by solid-state steering systems. Due to their compatibility with CMOS fabrication processes, silicon photonics based OPAs are promising candidates to become the next generation beam steering solution. However, due to the large thermo-optic coefficient of silicon, these phased arrays are extremely sensitive to temperature. Thermal management of silicon-photonic based OPAs requires not only heat dissipation of integrated active components, but also reduction of temperature gradients across the phased array. Here a novel concept for thermal management of silicon photonic OPAs is proposed and analyzed using finite-element simulations. The proposed concepts show a formidable efficiency in improving the heat dissipation as well as in reducing temperature gradients across the array.

Zusammenfassung

Micro manufacturing is dealing with the fabrication of structures in the order of 0.1 to 1000 µm. The scope of nano manufacturing extends the size range of manufactured features to even smaller length scales: below 100 nm. A strict borderline between micro and nano manufacturing can hardly be drawn, such that both domains are treated as complementary and mutually beneficial within a closely interconnected scientific community. Both micro and nano manufacturing can be considered as important enablers for high-end products. Especially, such products are enabled by micro and nano features and structures to incorporate special optical, electronic, mechanical, fluidic or biological functions into existing and new emerging products, and thus lead to unique selling points. Application fields include, but are not restricted to, precision instrumentation, sensors, metrology, energy harvesting, mechatronic systems, transport, medical technologies and life sciences. This Special Issue is dedicated to recent advances in research and development within the field of micro and nano manufacturing. The included papers report recent findings and advances in manufacturing technologies for producing products with micro and nano scale features and structures as well as applications underpinned by the advances in these technologies. In particular, the Special Issue covers the following topics: •Micro fabrication technologies, process chains and process characterization; •Novel product designs, micro-assembly technologies and micro-handling; •Surface engineering and interface nanotechnology; •Process modeling and simulation; •Processing and characterization of nanomaterials; •Micro and nano additive manufacturing technologies; •Micro and desktop factory concepts, systems, components and modules; •On-line monitoring and inspection systems/methods; •Applications of micro and nano technologies.

Zusammenfassung

Micro manufacturing involves dealing with the fabrication of structures in the size range of 0.1 to 1000 µm. The scope of nano manufacturing extends the size range of manufactured features to even smaller length scales—below 100 nm. A strict borderline between micro and nano manufacturing can hardly be drawn, such that both domains are treated as complementary and mutually beneficial within a closely interconnected scientific community. Both micro and nano manufacturing can be considered as important enablers for high-end products. This Special Issue of Applied Sciences is dedicated to recent advances in research and development within the field of micro and nano manufacturing. The included papers report recent findings and advances in manufacturing technologies for producing products with micro and nano scale features and structures as well as applications underpinned by the advances in these technologies.

Zusammenfassung

In the field, electronic devices are often experiencing switching cycles. With the trend of miniaturization and electrification, automotive electronic packages are facing increasingly critical reliability issues regarding current stressing and the accompanying Joule heating. In this work, the load capability of two surface-mounted shunt components subjected to cyclic current pulses is investigated. Asymmetric self-heating due to the Peltier effect is observed with infrared thermography in one of the shunt components, which leads to polarity in the microstructural evolution influencing the failure mode in the solder joint. Finite element method (FEM) is utilized to simulate the coupled electrical, thermal and mechanical fields in the assembly and to assess the response of the solder joints exposed to power cycling. Lifetime data are collected and statistically analysed based on the Weibull distribution.

Zusammenfassung

Laser induced selective activation and metallization of ceramics is a novel additive metal plating process enabling the application fine metallic paths or metallic surfaces on complex three-dimensionally shaped ceramic substrates. Metal deposition by electroless plating occurs selectively where the substrate has been locally activated by a preceding selective laser activation. The main influences on the process are the ceramic substrate material, its microstructural and optical properties as well as the laser type, laser process parameters and metallization parameters. Recent positive results with activation by a green picosecond laser were obtained only with oxygen vacancy containing alumina substrates sintered in hydrogen atmosphere. In order to be able to apply inexpensive conventional state-of-the-art sintering in air it was tried to modify the composition by doping with different oxides. 2 mass-% of fine particles of neodymium-, manganese-, samarium-, chromium-, nickel- iron-, ceria- and antimony doped tin-oxide were introduced into an alumina matrix by mixing and milling. Slip cast samples were sintered at 1500°C in air and machined. Laser activation was performed on polished sample surfaces using a Nd:YVO4 laser with a wavelength of 532nm and a pulse length of 10 ps. Electroless plating was performed with commercially available copper electrolytes. Microstructural properties, laser-matter interaction and metallization effectivity were investigated. Doping of alumina substrates with antimony doped tin-oxide, chromium-, iron- and nickel-oxide results in very good metallization of laser activated areas. Dopants enable plating larger areas and writing fine circuit paths to integrate microelectronic devices. Other additives were ineffective. The activation mechanisms triggered by the dopants is not fully understood yet. Separation and identification of single mechanisms of the dopants is required. The influence of dopants and laser activation on the mechanical properties is to be studied.

Zusammenfassung

In this work, a polymer microlens array (MLA) for a hyperspectral imaging (HSI) system is produced by means of ultraprecision milling (UP-milling) and injection compression molding. Due to the large number of over 12,000 microlenses on less than 2 cm², the fabrication process is challenging and requires full process control. The study evaluates the process chain and optimizes the single process steps to achieve high quality polymer MLAs. Furthermore, design elements like mounting features are included to facilitate the integration into the final HSI system. The mold insert was produced using ultraprecision milling with a diamond cutting tool. The machining time was optimized to avoid temperature drifts and enable high accuracy. Therefore, single immersions of the diamond tool at a defined angle was used to fabricate each microlens. The MLAs were replicated using injection compression molding. For this process, an injection compression molding tool with moveable frame plate was designed and fabricated. The structured mold insert was used to generate the compression movement, resulting in a homogeneous pressure distribution. The characterization of the MLAs showed high form accuracy of the microlenses and the mounting features. The functionality of the molded optical part could be demonstrated in an HIS system by focusing light spectrums onto a CCD image sensor.

Zusammenfassung

Polymer optics are widely used in various applications, replacing traditional glass lenses. The ability to create free-form and micro-structured optics, as well as fast replication, gives them major advantages over traditional glass lenses. However, the fabrication of complex optical components requires full process control and understanding of influencing factors on the quality of the polymer optical parts. In this work, a curved diffractive optical element (DOE) is fabricated using injection compression molding. Different gate designs were evaluated and the movement of the compression stamper was optimized to obtain good filling behavior. The process stability was analyzed and improved by controlling the melt temperature precisely. Finally, the molding parameters were optimized, focusing on the mold temperature, melt temperature and compression force. Curved diffractive optical elements were replicated with feature sizes of 1.6 μm. The experiments showed that all aspects of the molding process have to be controlled perfectly to produce complex polymer optics. High mold temperatures and compression force are necessary to replicate micro-structured features. The work presents a broad investigation and description of the fabrication process and their influences.

Zusammenfassung

Light-emitting diodes (LEDs) have increasingly replaced conventional lamps in the fields of general lighting and consumer electronics. In addition to the sharp price fall, this is also due to the significantly higher energy efficiency and the smaller, more compact design. Recently, their robustness and reliability have also reached a level of quality that surpasses the characteristics of conventional light sources such as halogen and fluorescent lamps. Characteristics, such as excellent design freedom and the possibility for functional integration, highlight the main qualities of molded interconnect devices (MIDs). The use of this technology does not only open doors to extend the application field of LEDs to new products but also presents challenges to the lighting industry. There are many studies dealing with the reliability of LEDs as well as with the usability of the MID technology in different fields. But, the lack of experience from the manufacturers regarding the behavior of this interesting configuration (LED/MID) over the entire life cycle prevents this technology from establishing and consolidating its existence. As LEDs in the automotive sector, especially within headlamps, assume increasingly powerful lighting tasks and are no longer used exclusively for signal transfer or for displays, thermal properties of the substrate materials and the thermo-mechanical behavior of the assembly are particularly relevant. In this context, this paper presents a deep and detailed reliability investigation of this system (LED/MID) and examines the influence of the MID substrate choice on the long-term performance of the LED. The impact of the forward current and of the ambient temperature on the junction temperature of the LED is a proven fact. Therefore, the MID effect was inspected under different operating conditions based on infrared thermography. After analyzing the occurred failure mechanisms, by means of X-ray analysis, thermal transient testing and microscopy, the resulting lifetime model is also presented and discussed.

Zusammenfassung

Higher energy efficiency, more compact design, and longer lifetime of light-emitting diodes (LEDs) have resulted in increasing their market share in the lighting industry, especially in the industries of consumer electronics, automotive, and general lighting. Due to their robustness and reliability, LEDs have replaced conventional light sources, such as fluorescent lamps. Many studies are examining the reliability of LEDs as such or investigating their long-term behavior on standard printed circuit boards (PCB). However, the thermal performance of LEDs mounted on nonconventional substrates is still not explored enough. An interesting example for this is the molded interconnect devices (MID), which are well known for the great design freedom and the great potential for functional integration. These characteristics not only underline the main abilities of the MID technology, but also present some challenges concerning thermal management. The long-term behavior of LEDs on MID is still quite untapped and this prevents this technology from consolidating its existence. In this context, this work highlights a developed test setup aimed at investigating LEDs, mounted on molded interconnect devices, under combined stress conditions. The results of the reliability study, as well as the resulting lifetime model, are also illustrated and discussed.

Zusammenfassung

A Physical Unclonable Function uses random and inherent properties of a physical entity and can be used to uniquely identify components e.g., for anti-counterfeiting purposes. In this work we demonstrate that the surface patterns of injection moulded plastic components themselves are inherently unique and hence can be used as a PUF for reliable and secure identification. We further demonstrate that these unique surface patterns are easily accessible since they can be photographed with a simple camera set-up. This is exemplarily demonstrated for two different plastic materials on an overall of 200 injection moulded components. A set of brief experiments further examines the PUF's robustness towards real life conditions. This approach might be useful for secure identification and authentication of components or a label-free tracking.

Zusammenfassung

Individual traceability of components enables efficient quality control, improving operational efficiency, or smart manufacturing approaches like big data analysis as well as customized mass production. Conventional track and trace solutions however, require a tag or label which is often not attachable due to e.g., spatial or economic reasons. A promising alternative is the identification of components based on individual, inherent surface patterns. For a set of 115 printed circuit boards, it is shown that fiducial markers, which are commonly used for alignment of components, can possess such individual surface patterns and hence serve as unique identifier. As the investigations are based on industrial conditions, the paper transfers the approach of label-/tag-free traceability from laboratory to an application in an industrial environment. Furthermore, faultless traceability of all samples within a SMD assembly line is achieved demonstrating the robustness of the identification against changes of the surface.

Zusammenfassung

With the introduction of lead-free solder alloys, the effect of voids on solder joint reliability has rapidly gained importance. In this study, a first analysis of X-rayed CR0805 solder joints shows a significant reduction in void content, from 20% down to 2.5%, after vacuum soldering. The statistical analysis of the void distribution demonstrates that the vacuum option reduces number of voids and median diameter of voids in comparison to the convection soldering process. A subsequent accelerated thermal cycling test of these analysed test vehicles, according to JESD22-A104D, indicates the tendency of a higher characteristic life time for higher void content. In contrast to these findings, the 1% to failure criterion reveals a higher reliability for lower voiding. During the finite element method (FEM) modelling part of this study, two modelling approaches of void implementation into solder joint geometry are investigated: modelling with a constant volume of the standoff for different void contents, and a modelling approach with a random combination of void content and volume of standoff. The modelling approach with the random combination reveals that voids can reduce the lifetime in the “worst case” parameter combination. In particular, the 1% time to failure rate indicates a quantitative correlation with the experimental results. Furthermore, the FEM results suggest a higher impact on reliability for a single void in comparison to a distribution of multiple voids with similar void content. Finally, the FEM study shows a high sensitivity of predicted life time with respect to the standoff height. Based on this finding, the CR0805 solder joint geometry is examined using optical inspection and cross-section polishes with the outcome that the better wetting behaviour during vacuum soldering causes a reduction of the solder alloy volume and consequently further decreases the standoff height.

Zusammenfassung

Packaging represents an important part in the microintegration of sensors based on microelectromechanical system (MEMS). Besides miniaturization and integration density, functionality and reliability in combination with flexibility in packaging design at moderate costs and consequently high-mix, low-volume production are the main requirements for future solutions in packaging. This study investigates possibilities employing printed circuit board (PCB-)based assemblies to provide high flexibility for circuit designs together with film-assisted transfer molding (FAM) to package sensors. The feasibility of FAM in combination with PCB and MEMS as a packaging technology for highly sensitive inertia sensors is being demonstrated. The results prove the technology to be a viable method for damage-free packaging of stress- and pressure-sensitive MEMS.

Zusammenfassung

Cost-effective electronic packaging technology plays a vital role in the manufacturing industry with ever increasing demand for microelectronics and microsystems. The application of thermoset encapsulation of electronic parts offers a wide range of advantages with respect to thermal, mechanical and chemical properties. Transfer Molding, mainly available in the Far East, is dominantly used for the manufacturing of such polymeric packages 2. Thermoset injection molding extends a good scope of advantages over transfer molding like availability in Europe and ease of raw material handling. The implementation of thermoset injection molding for encapsulation of electronic components provides the European small and medium-sized enterprises (SMEs) with access to customized packaging solutions. The feasibility of this implementation is defined and tested in this work.

Zusammenfassung

Reliability aspects are crucial for the success of every technology in industrial application. Regarding interconnect devices, several methods are applied to evaluate reliability of conductor paths like accelerated environmental tests. Especially, molded interconnect devices (MID), which enable numerous applications with three-dimensional (3D) circuitry on 3D shaped injection-molded thermoplastic parts are often under particular stress, e.g., as component of a housing. In this study, a new test method for evaluating the flexural fatigue strength of conductor paths produced by the laser-based LPKF-LDS® technology is presented. For characterization of test samples, a test bench for flexural fatigue test was built up. A result of the flexural fatigue test is a characteristic Woehler curve of the metal layer system. Applying this new test method, essential influencing parameters on the reliability of MID under mechanical load can be identified. So, the metal layer system as well as the geometric parameters of the metal layer is crucial for the performance. Furthermore, test specimens are tested under different types of mechanical load, i.e., tensile stress and compressive stress. For a holistic view on reliability of MID, experimental results are discussed and supported by simulations. An important finding of the study is the advantage of nickel-free layer systems in contrast to the Cu/Ni/Au layer system, which is often used in MID technology.

Zusammenfassung

Since the introduction of lead-free solder alloys, the impact of voids in solder joints has rapidly gained in importance. Particularly in power electronics, voids in solder joints can reduce their reliability due to less heat dissipation and a significant reduction of the cross-sectional area. While void formation in the printed circuit board (PCB) technology has been the focus of many research projects, the increasing application of molded interconnect devices (MIDs) demands a vivid understanding of void formation and its impact on reliability. This report will show that those processes specific to MID technology do not significantly influence the void formation in SAC305 solder deposits. The processed different roughness levels on Vectra, Vestamid, and FR4 substrate materials show no significant impact on void formation. The surface finish metallization was detected as the most important factor. Especially, the chemical-Sn (iSn) surface finish is inclined to having more voids compared to a nickel-phosphor-gold (NiP-Au) finish. Furthermore, three solder processes were investigated: convection, condensation, and vacuum-condensation soldering. The vacuum-condensation processes significantly reduced the voids in the Sn-3.0Ag-0.5Cu (simplified as SAC305) solder joints of CR0805, MLF20, and switches on all the investigated substrates. An accelerated thermal cycling test of these components according to JESD22-A104D demonstrates no significant effect of the void content of <;19% on the solder joints' reliability. Finally, the result of accelerated thermal cycling shows the possibility to achieve an equivalent lifetime of the solder joints on Vectra in comparison to the FR4 substrate.

Zusammenfassung

This paper focuses on packaging of small-scale thermoelectric generators (TEGs) for energy harvesting applications in sensor nodes for industry 4.0 and for the Internet of Things. The TEGs are suitable to enable self-powered sensor systems with unlimited energy lifetime, but they have to withstand high mechanical loads during the assembly and packaging process and further stress due to the mismatch of the coefficient of thermal expansion of the different materials. Devices with different underfills (UFs) and stress decoupling thermal adhesives were evaluated with a shear force test apparatus and a four-line bending test together. In addition to these mechanical tests, the thermal influence of the UF on the system performance was investigated with measurements, finite element method, and computational fluid dynamics simulations. The shear force per area could be enhanced up to the factor of two by using capillary UF. All TEGs with and without UFs passed the reliability investigations without any electrical defects. All TEGs with UF passed the given quality criteria with the four-line bending test. With some of the stress decoupling thermal adhesives, the TEGs could withstand the loads without UF. The simulation model was evaluated with a measurement setup, and the differences between the simulation model and the measurements concerning the temperature difference of the TEGs were in an acceptable range (<;21%). Furthermore, the influence of the UF on the temperature difference of the TEGs in the given measurement scenario was smaller than 15%, which makes the application of a UF a realistic approach.

Zusammenfassung

Räumlich gestaltete mechatronische Systeme wie z.B. dreidimensionale spritzgegossene Schaltungsträger (Moulded Interconnect Devices - MID) sind heute, oft unsichtbar für den Endanwender, Bestandteil vieler Produkte. Die Freiheiten der räumlichen Formgebung des Spritzgusses mit einer Vielzahl von elektrischen, aber auch optischen, mechanischen oder fluidischen Funktionen zu kombinieren bietet einzigartige und bestechende Möglichkeiten.

Zusammenfassung

New concepts for an impact actuated micro shift valve are presented which are useful, e.g. as implant for the hydrocephalus disease. Such an implant must fulfil requirements, such as using biocompatible materials, a separation of the actuator from the fluid, MRT safety and low-energy consumption in order to allow a battery-powered system. The concepts are based on the impacts that transmit an impulse into the interior of the valve through the casing, switching the valve. In order to predict the energy transmitted into the valve, an elastic multibody model is created, verified with full finite element simulations and experiments on scaled-up models. Using this model, the most important effects and parameters are discussed. Also, fluid effects are included into the elastic multibody model for a qualitative assessment of its influence on the efficiency. The simulations are compared to experiments performed with a scaled model for two different cases. Two designs of a shift valve based on impact actuation are built as prototypes and tested.

Zusammenfassung

Digitale Drucktechniken wie Inkjet- und Aerosol-Jet-Technologie bieten die Möglichkeit zur Integration zusätzlicher Funktionalität auf unterschiedlichen Substraten. Im Beitrag wird auf realisierbare Strukturen wie Leiterbahnen und Sensoren eingegangen. Dabei liegt der Fokus auf Untersuchungen kapazitiver Sensoren für Berührung und Feuchte. Die Ergebnisse dieser Untersuchungen zeigen, dass gedruckte kapazitive Sensorik das Potential zur Integration in marktfähige Produkte hat. Digital printing technologies like inkjet and aerosol jet provide the possibility to integrate additional functionality on different substrates. This article addresses feasible structures such as conductive tracks and sensors. In particular the focus lies on investigations of capacitive touch and humidity sensors. The results of these investigations show that capacitive sensors have the potential to be integrated into marketable products.

Zusammenfassung

Leiterstrukturen auf spritzgegossenen Schaltungsträgern werden heutzutage vorwiegend mittels LPKF-LDS®- oder 2K-MID-Technik aufgebaut. Digitale Drucktechniken wie Inkjet- und Aerosol Jet®-Technologie bieten zusätzliche Möglichkeiten zur Integration weiterer Funktionalität wie Leiterbahnkreuzungen oder Leiterstrukturen mit temperatur- und dehnungssensitiven Eigenschaften. Die Kontaktierung von gedruckten Leiterbahnen kann beispielsweise mittels isotrop leitfähigem Kleben erfolgen. Weiterhin können Klebetechniken zur Montage von SMD auf gedruckten Leiterbahnen eingesetzt werden.

Zusammenfassung

Rotary sensors are an essential component in numerous applications where a rotation movement has to be detected. With optical encoders, a high angular resolution can be achieved. As a disadvantage, the resolution enhancement is associated with increasing cost. To overcome this issue, a coding principle is presented that uses a diffractive solid measure on a microstructured plastic disc. Like a DVD, this encoder disc can be manufactured in a cost effective injection molding process. For this approach, a differential incremental code, as well as an absolute code, has been developed.

Zusammenfassung

Um der wachsenden Nachfrage nach hochauflösenden und dennoch kostengünstigen optischen Drehgebern gerecht zu werden, entstand die Idee, in optischen Drehgebern anstelle der typischerweise verwendeten Kodierscheibe aus Glas eine mikrostrukturierte Kunststoffscheibe ähnlich einer CD oder DVD einzusetzen. Diese kann auf einfache Weise in einem effizienten Spritzprägeprozess hergestellt werden. Damit wird es möglich, die hochgenaue Maßverkörperung mittels eines kostengünstigen Verfahrens in hohen Stückzahlen zu fertigen.

Zusammenfassung

Moulded Interconnect Devices (MIDs) sind spritzgegossene Kunststoff-Formteile, die selektiv mit einer Metallbeschichtung als Leiterbild versehen werden. Aufgrund der großen dreidimensionalen Gestaltungsfreiheit beim Kunstoffspritzguss und der Reduktion von Bauteilen hat die MID-Technik in den letzten Jahren stark an Bedeutung gewonnen. HSG-IMAT und IZFM beschäftigen sich seit 1998 mit Aufbau- und Verbindungstechniken für Mikrosysteme auf Basis von MID-Techniken. Seit Beginn wird dabei ebenfalls die Eignung dieser innovativen Technik für die Integration von sensorischen und aktorischen Funktionen untersucht. Beschleunigungssensoren, Neigungssensoren, Berührungssensoren und Mikroventile wurden bereits realisiert, sowie Konzepte für hoch auflösende Drehwinkelsensoren entwickelt.

Zusammenfassung

We report on an innovative low cost concept for the fabrication of micromechanical capacitive inclination sensors. The concept based on moulded interconnect device (MID)-technology where three dimensional polymer devices are fabricated by injection moulding and covered by a structured metal layer using electroless plating and laserablation. To demonstrate the principle of operation we fabricated and characterized first demonstrator devices using standard PCBs with different electrode designs for different measurement ranges.

Zusammenfassung

We report on a new metallization process on thermoplastic materials for molded interconnect devices (MIDs) to obtain smooth and adherent metal layers. The process includes deposition of a thin chromium interlayer and a subsequent copper layer by physical vapor deposition (PVD) on commercial liquid crystalline polymers (LCPs) followed by electroless plating of nickel and immersion gold to the desired thickness. Adhesion strength of the metal layer to LCP could be further improved by plasma treatment of the LCP substrate before plating. The properties of the multilayer metal system were compared to an electrolessly plated only sample. By combining PVD and electroless plating we obtained smooth metal layers with good adhesion to LCP. No decrease in adhesion strength of the metallization (Cu/Cr layer) was observed after electroless plating. We conclude that combination of PVD and electroless plating is well suited for fabrication of finest pitch metal layers on MIDs.

Zusammenfassung

Application of ultrashort voltage pulses to a tiny tool electrode under suitable elec-trochemical conditions enables precise three-dimensional machining of stainless steel.In order to reach submicrometer precision and high processing speed, the formationof a passive layer on the workpiece surface during the machining process has to beprevented by proper choice of the electrolyte. Mixtures of concentrated hydrofluoric andhydrochloric acid are well suited in this respect and allow the automated machining ofcomplicated three-dimensional microelements. The dependence of the machining precisionon pulse duration and pulse amplitude was investigated in detail.

Zusammenfassung

Mikrosystemtechnik. Die MID-Technik erlaubt die Integration elektrischer und fluidischer Funktionen in Gehäuse für mikrosystemtechnische Bauteile. In der Hahn-Schickard-Gesellschaft wurde ein Durchfluss-Sensorsystem mit einem thermischen Strömungssensor und einem MID-Gehäuse realisiert.

Zusammenfassung

We report on an innovative concept for the fabrication of micromechanical sensors and actuators, where polymer devices fabricated by injection molding are covered by metal layers of copper, nickel–phosphorus and gold using electroless plating. First we discuss the mechanical properties of miniaturized mechanical polymer beams covered with a metal layer. We find that at a sufficient metal layer thickness the mechanical properties of the beams are dominated by the metal cover surrounding the beam. Furthermore, we designed and fabricated a differential accelerometer from metallized liquid crystal polymer and present very first experimental results. We find a sensitivity and frequency response which is well suited to cover a broad band of applications. We conclude that this new technology can be used to fabricate diverse micromechanical sensor or actuator devices.

Zusammenfassung

In Deutschland ist die Physikalisch Technische Bundesanstalt (PTB) in Braunschweig für die Verbreitung der gesetzlichen Zeit verantwortlich (Zeitgesetz). Für dieses Zeitgesetz wurde die Installation des Zeitsignalund Normalfrequenzsenders DCF77 notwendig. Erste Testaussendungen gab es 1956, offizieller Sendebeginn war der 1.Januar 1959. Seit dem 1. September 1970 werden Normalfrequenz (77,5 kHz Träger) und Zeitmarken gesendet, das heißt definierte Absenkung des Trägers zu Beginn jeder Sekunde = Sekundenmarke und keine Absenkung in der 59. Sekunde = Minutenmarke. Damit war die Übertragung einer kodierten Zeitinformation geschaffen. Die Empfänger waren industrielle Funkuhren mit getrennter Antenne und einem industriellen Gehäuse (19 “Einschub). Der Empfang war allerdings nur mit abgesetzter Antenne und an einem geeigneten Standort möglich. Der Wunsch nach einer „Gebrauchsfunkuhr “ war mit der Forderung verbunden, Antenne, Empfänger und Anzeige komplett in einem Gehäuse unterzubringen. Außerdem mußte diese Uhr an einem beliebigen Ort aufgestellt werden können. Nebenbedingungen waren vollautomatische Zeigereinstellung, möglichst schnelle Positionierung der Zeiger (mehrere Antriebsmotoren erforderlich)und fehlerkorrigierende Maßnahmen. Dies war 1986 der Ausgangspunkt für ein Verbundprojekt des Instituts mit der Uhrenindustrie. Das Ziel war eine vollautomatische Funkuhr (automatische Zeigerdetektion) einschließlich Antenne, die in das handelsübliche Uhrgehäuse passen sollte. Das Projekt wurde erfolgreich abgeschlossen, und es standen ein Prototyp und die entsprechenden integrierten Empfänger- und Auswerteschaltungen zur Verfügung.

Zusammenfassung

An electrostatically driven silicon micro scanning mirror (MSM) for one-dimensional (1-D) and two-dimensional (2-D) deflection of light is presented. A special configuration of the driving electrodes allows the use of small electrode gaps without restricting the deflection of the plate geometrically. In this paper, the starting of the oscillation and the operation of the scanner is discussed. Experimental results show that scan angles of up to 60/spl deg/ can be achieved at a driving voltage of only 20 V. The 2-D deflection of a laser beam is obtained by a gimbal mounting of the mirror plate. For the fabrication of the devices, SOI-wafers are used as the base material. The mechanical structures are defined by a deep silicon etch. For the electrical isolation of areas on the movable frame, polysilicon-filled trenches are used. The mechanical stability of the scanners is tested. The devices resist shocks of more than 1000 g and show no change of the resonance frequency even after long run tests of 7/spl times/10/sup 9/ periods.

Zusammenfassung

Das Ceramic-Injection-Molding (CIM) ist ein Verfahren zur Herstellung keramischer Bauteile mit ho- her geometrischer Komplexität. Eine besondere Herausforderung im CIM-Prozess sind die adhäsiven Entformungs- kräfte, die zu Bauteildefekten wie Rissen oder Verformungen führen, die oft erst nach dem energieintensiven Sin- terprozess sichtbar werden. In dieser Untersuchung wurde ein Messwerkzeug eingesetzt, um die adhäsiven Ent- formungskräfte unabhängig von Werkzeugbewegungen zu bestimmen. Zwei Feedstocks auf Al₂O₃-Basis mit unter- schiedlichen Bindersystemen (EnCeram und 83/83G) wurden getestet, wobei die Werkzeugoberflächen (geschlif- fen, erodiert und poliert) über Einsätze sowie die Werkzeugtemperatur variiert wurden. Die Ergebnisse zeigen, dass die Entformungskräfte durch eine höhere Werkzeugtemperatur und eine rauere Werkzeugoberfläche (geschliffen oder erodiert) deutlich reduziert werden können. Die abrasive Eigenschaft des Feedstocks bzw. der Al₂O₃ Partikel führte bereits nach 750 Zyklen zu sichtbaren Veränderungen der Oberflächen, insbesondere bei erodierten Ober- flächen. Die Untersuchung bildet die Grundlage für zukünftige Analysen zur Oberflächengüte und inneren Defekten der finalen Keramikbauteile. Ceramic-Injection-Molding (CIM) is a process for producing ceramic components with high geometric complexity. A key challenge in the CIM process is the adhesive demolding forces which can lead to defects such as cracks or deformations that often only become apparent after the energy-intensive sintering process. In this study, a measurement tool was used to quantify adhesive demolding forces independently of tool movements. Two Al₂O₃-based feedstocks with different binder systems (EnCeram and 83/83G) were analyzed while varying tool surfaces (ground, eroded, and polished) by using inserts and tool temperatures. Results indicate that higher tool temperatures and a rougher mold surface (ground or eroded) significantly reduce demolding forces. The abrasive property of the feedstocks or the Al₂O₃ particles caused visible changes to the surfaces after only 750 cycles, particularly on eroded surfaces. This investigation serves as a basis for further analyses of surface quality and internal defects in finished ceramic components.

Zusammenfassung

In injection molding, the flow behavior of plastic materials in the mold cavity can be influenced by modifying the molding parameters as well as the condition of the mold surface in terms of roughness or material. Previous studies have reported on altered flow of plastics on physical vapor deposited hard coatings, which could potentially lead to an improved replication of micro-sized features in micro injection molding. The objective of the presented study was to investigate the filling of plastic material into microstructures for the surface condition of conventional tool steel and for the condition of a physical vapor deposited chromium nitride coating. For the experiments, two mold inserts of conventional tool steel were manufactured and polished to optical roughness. Truncated pyramid-shaped microstructures were created by micro-milling and were placed along the flow path of a disc-shaped component with a thickness of 1 mm. Subsequently, one mold insert was coated with a commercially available chromium nitride. The plastic material used in the molding experiments was polycarbonate. In order to ensure comparable flow conditions within the cavity for both surface conditions, injection molding was conducted at constant pressures, which were varied from 400 bar to 2000 bar. Furthermore, the mold and injection melt temperature were varied to study their influence on the filling for both surface conditions. The filling of the microstructures was evaluated using both light microscopy imaging and quantitative measurements of the replicated microstructures. The results indicate that different filling states can be observed depending on the surface condition and the processing parameters.

Zusammenfassung

This work shows the possibility to generate single-mode squeezed light using four-wave mixing in micro-ring resonators and determines the phase sensitivity in a lossy Mach-Zehnder Interferometer. It is shown that sub-shot noise measurements can be achieved.

Zusammenfassung

Nowadays, there is a growing demand for structures in the micrometer and submicrometer regime for electrochemical and optical applications to fabricate circuit paths or optical gratings. Therefore, the aim of this work is to show the applicability of a simple and inexpensive method to manufacture micrometer- and submicrometer structures of ultrathin metal coatings on polymer substrates of cyclic olefin copolymer (COP) as well as on glass using maskless photolithography followed by lift-off. To enhance the adhesion of the photoresist on the polymer substrates surface pretreatments of the polymer substrates, e.g., by glow discharge or atmospheric plasma treatment were executed. The lithography process was carried out using a sprayed negative photoresist on glass and COP substrates exposed to ultraviolet light via a micromirror assay and without a mask. Based on the exposure limit and an initial proof of concept, gratings with a line width of 100 µm and a period of 200 µm were manufactured. After development, no adhesion layers were applied to facilitate fabrication and minimize costs. Thus, the substrates were sputtered with 50 nm gold layers, which were lifted off with acetone. During the processing, the factors influencing the accuracy of the structures, such as prebake, postbake and development parameters, were determined and an optimal parameter setting was derived.

Zusammenfassung

This work is concerned with the examination of one-dimensional stress effects in mode-split, open-loop MEMS gyroscopes with the goal to predict the sensitivity change under printed circuit board (PCB) bending stress. Measurements with ten triaxial gyroscopes are compared to simulation results based on a detailed analytical model. The dependencies of gap distance and overlap of the in- and out-of-plane detection capacitances related to bending stress are formulated. Sensitivity change is predicted with 75% accuracy and the sign of gradient is correct for all measurements. Besides the change in geometry parameters of capacitances the effects of mechanical bending stress on the entire system are discussed. The purpose of the paper is to show the fundamental relationships on which all further considerations regarding MEMS gyroscopes under PCB stress are built.

Zusammenfassung

Die Benetzung von Schmelze-berührenden Maschinenkomponenten sowie die Anhaftung von erstarrtem Kunststoff auf dem Formwerkzeug basiert auf Wechselwirkungen an der Grenzfläche zwischen Kunststoff und Werkzeugmaterial. Ein Ansatz zur Charakterisierung der Benetzbarkeit von Festkörperoberflächen ist die Bestimmung der freien Oberflächenenergie auf Basis von Kontaktwinkelmessungen. Bisherige Studien ermittelten die freie Oberflächenenergie von verschiedenen Hartstoffschichten meist durch Kontaktwinkelmessungen bei Raumtemperatur oder basierend auf einem statischen Messverfahren, welches nahezu keine Reproduzierbarkeit aufweist. Um die Benetzbarkeit von Hartstoffschichten für die Kunststoffverarbeitung zu bewerten, wurden in dieser Studie dynamische Kontaktwinkelmessungen von zwei Prüfflüssigkeiten auf poliertem Stahl sowie einer Titannitrid- (TiN), zwei Chromnitrid- (CrN) und einer amorphen Kohlenstoffbeschichtung (a-C:H:Si) im Entformungstemperaturbereich von 60 °C bis 140 °C durchgeführt. Anschließend wurden die freien Oberflächenenergien der Beschichtungen für den betrachteten Temperaturbereich nach der Methode von Owens, Wendt, Rabel und Kaelble bestimmt. Die Ergebnisse zeigen, dass die CrN-Beschichtungen die geringste freie Oberflächenenergie aufweisen. Im Vergleich zeigte sich für alle Hartstoffschichten eine Abnahme der freien Oberflächenenergie mit sich erhöhender Temperatur. Die chemische Zusammensetzung der Probenoberfläche scheint bei gleichbleibenden Messbedingungen für glatte Oberflächen der bestimmende Faktor für die Höhe der freien Oberflächenenergie zu sein. The wetting of melt-facing surfaces as well as the sticking of solidified plastic on molding tools is related to surface effects between plastic materials and mold material. One approach to quantify the wetting on solid surfaces is the determination of the free surface energy. Several studies determined the free surface energy of hard coatings used in polymer processing based on the drop shape analysis. These measurements were, however, mostly conducted at room temperature, which is not comparable to molding temperatures, or were limited to static contact angle measurements, which are nearly non-reproducible. In this study, the wetting of hard coatings used in polymer processing was investigated by measuring the advancing contact angle of two test fluids on a titanium nitride, two differently deposited chromium nitride and one diamond-like carbon coating at relevant demolding temperatures in the range from 60 °C to 140 °C. The results showed the smallest free surface energy values for the two chromium nitride coatings. The comparison of all investigated coatings revealed a decline of the free surface energy with increasing solid temperature. The chemical composition of the material seems to be a determining factor for smooth surfaces and constant measuring conditions.

Zusammenfassung

Die kostengünstige Herstellung von Hybridoptiken kann durch die Replikation eines mikrostrukturierten Werkzeugeinsatzes mittels Spritzprägen realisiert werden. Das Werkzeug wird mittels Laserlithografie und anschließender galvanischer Abformung hergestellt. Im Vordergrund dieses Herstellungsverfahrens liegt die Verbesserung der Lagetoleranz zwischen der diffraktiven und refraktiven Fläche.

Zusammenfassung

The research presented in this work compensates non-orthogonality over temperature stress effects in low-cost open-loop MEMS gyroscopes using neural networks (NN) for a sensor individual compensation to improve the sensor performance. The non-orthogonality is included in the sensor cross-axis sensitivity (CAS) of MEMS gyroscopes. Using the model-agnostic meta-learning algorithm (MAML) as a self-calibration algorithm and one initial measurement after soldering, an individual compensation model is generated for each sensor that predicts the non-orthogonality using the MEMS gyroscope's quadrature value as an input. It will be shown that a sensor-individual model outperforms a compensation model that should fit for all sensors at once like linear regression or classic NN and improves the non-orthogonality by 82.7 %, 7.5 % and 70 % for yx-, zx-, and zy-non-orthogonality,

Zusammenfassung

Hard coatings can be applied onto microstructured molds to influence wear, form filling and demolding behaviors in microinjection molding. As an alternative to this conventional manufacturing procedure, “direct processing” of physical-vapor-deposited (PVD) hard coatings was investigated in this study, by fabricating submicron features directly into the coatings for a subsequent replication via molding. Different diamondlike carbon (DLC) and chromium nitride (CrN) PVD coatings were investigated regarding their suitability for focused ion beam (FIB) milling and microinjection molding using microscope imaging and areal roughness measurements. Each coating type was deposited onto high-gloss polished mold inserts. A specific test pattern containing different submicron features was then FIB-milled into the coatings using varied FIB parameters. The milling results were found to be influenced by the coating morphology and grain microstructure. Using injection–compression molding, the submicron structures were molded onto polycarbonate (PC) and cyclic olefin polymer (COP). The molding results revealed contrasting molding performances for the studied coatings and polymers. For CrN and PC, a sufficient replication fidelity based on AFM measurements was achieved. In contrast, only an insufficient molding result could be obtained for the DLC. No abrasive wear or coating delamination could be found after molding.

Zusammenfassung

Microsystems and interconnect devices based on ceramic substrate materials are used in many high temperature and power applications due to their superior thermal properties. With the current state-of-the-art pro-cesses, such as direct-bonded copper or high/low temperature co-fired ceramics, only 2D or multilayer struc-tures can be realized. In this paper, we present a fully digital, selective and additive process chain based on direct laser-induced activation and subsequent autocatalytic metallization of injection molded Al2O3-based substrates to produce 3D-ceramic interconnect devices. In order to laser-activate the Al2O3, it has either to be sintered in H2 atmosphere or doped with Cr2O3. The resulting selective metallization shows an adhesive strength of up to 50 N/mm² and can be connected with common interconnection technologies, such as reflow soldering, wire bonding etc. Thus, the developed process chain offers new possibilities in ceramic circuit carrier design and the integration into complex microsystems.

Zusammenfassung

Diese Arbeit beschreibt die Entwicklung eines mikro-integrierten multispektralen Bildgebungssystems für die hyper-spektrale Bildgebung (HSI). Ziel ist es, durch den Einsatz von polymeren optischen Komponenten die Integrations-dichte zu erhöhen, das Gewicht zu reduzieren und gleichzeitig die Funktionalität im Vergleich zu klassischen HSI-Ka-merasystemen zu verbessern. Wirtschaftlichen Vorteile einer vereinfachten Montage durch direkte Integration von Be-festigungselementen als auch die Möglichkeit der Massenproduktion von Polymeroptiken werden betrachtet. Eine Stra-tegie zur Integration in ein Kamerasystem wird entwickelt, welche die Anforderungen für die Mikromontage aller Kom-ponenten erfüllt. Es werden Methoden zur Mikromontage eines polymeren Mikrolinsenarrays (MLA) mit 12.000 Mikrolinsen in Bezug auf die Positionierung eines Charge-Coupled Device (CCD) Chips sowie eines Beugungsgitters ange-wendet. Die direkte Integration von Befestigungselementen in das MLA ermöglicht dabei eine ultrakompakte Montage mit einer reduzierten Anzahl von Montagevorgängen. Die Ausrichtung der Spektrallinien auf die CCD-Pixel ermöglicht die Optimierung der Anzahl der auf einem einzigen Chip abgebildeten Spektren. Die Funktionalität des Systems wird demonstriert und stellt eine technologische Verbesserung für eine Vielzahl von Anwendungen dar, die von der Verfüg-barkeit eines solchen Systems in Bezug auf Einfachheit, Kosten, Größe und Gewicht profitieren können. This work describes the development of a micro-integrated multi-spectral imaging system for hyperspectral imaging (HSI). The aim is to employ polymeric optical components to increase integration density and reduce weight while provid-ing improved functionality compared to classical HSI camera systems. Economic advantages of both, simplified assembly by direct integration of mounting features and the ability of mass production of polymer optics are being addressed. An integration strategy into a camera system is developed, providing the required features for micro-assembly of all compo-nents. Methods for micro assembly of a polymeric microlens array (MLA) with 12.000 micro lenses in relation to the positioning of a Charge-Coupled Device (CCD) chip as well as a diffraction grating are applied. The direct integration of mounting features into the MLA allows for ultra-compact assembly with a reduced number of assembly processes. Fur-thermore, it enables the alignment of spectral lines to the CCD pixels, thus optimizing the number of spectra mapped on a single chip. The functionality of system is demonstrated, presenting a technological improvement for a large variety of applications, which may profit from the availability of such a system in terms of simplicity, costs, size and weight.

Zusammenfassung

Geräteelektronik und dazugehörige Sensoren sind in modernen Anwendungen steigender mechanischer, thermischer und chemischer Beanspruchung ausgesetzt. Dabei werden die Elektroniken in vielen Anwendungsbereichen mit Duroplasten, im Speziellen mit Epoxidharzformmassen (Epoxy Moulding Compounds, EMC), in einem Prozessschritt mit dem Spritzgussverfahren vollständig verkapselt. Die Umsetzung der Ankontaktierung der Gesamtsysteme für den elektrischen Zugang von außen ins Innere einer Duroplastverkapselung ist von besonderer Bedeutung. In der Praxis kommen hierfür meist metallische Steckerkontakte zum Einsatz, die als Teilbereich eines Gesamtsystems im Spritzgussverfahren mit Kunststoff verkapselt werden. Jedoch bringt diese Vorgehensweise Herausforderungen mit sich, da die Schnittstelle zwischen den metallischen Steckerkontakten und dem Kunststoff eine Schwachstelle für die Zuverlässigkeit darstellt. So wurden im Rahmen der Untersuchungen metallische Steckerkontakte aus Kupfer-Nickel-Zinn-Legierung (CuNiSn) und Bronze (CuSn6) verwendet. Die Steckerkontakte aus CuNiSn wurden weiterführend mit Silber (Ag) und Zinn (Sn) beschichtet. Für die Abmusterung des Metall-Kunststoff-Verbundes wurde ein Spritzgusswerkzeug nach den Designregeln der EMC-Verarbeitung ausgelegt und hergestellt. Die Untersuchungen zur Zuverlässigkeit des Metall-Kunststoff-Verbundes erfolgte mittels Scherversuchen und Dichtheitsprüfung. Die Ergebnisse der Untersuchungen zeigen, dass durch den Einsatz verschiedener Materialkombinationen die Zuverlässigkeit der Metall-Kunststoff-Verbindungen erhöht werden kann.

Zusammenfassung

Molding techniques allow the replication of surface structures to enable improved or novel functions for optics, fluidics and further applications. In general, the molding process can be facilitated by means of antiadhesive-coated molds due to a reduction of demolding forces, wear or prevention of heat dissipation. Consequently, employing coated molds, an improved demolding of features with submicron dimensions and high aspect ratio can be expected. In order to achieve adequate results regarding the replication of nanostructures, accurate mastering techniques to structure the coating are required. One possible technique is focused ion beam (FIB) writing, which was investigated in this study regarding its suitability to mill structured surfaces of submicron dimensions into coated mold inserts. Mold inserts were coated with a thin-film diamond-like carbon (DLC) and chromium nitride (CrN) as well as electroless plated nickel-phosphorus (NiP). The coatings were examined by means of SEM imaging and roughness measurements regarding their applicability for the creation of nanostructures. Subsequently, a test pattern was written into the coatings using a FIB-SEM dual beam system. The test pattern consisted of the USAF test chart target groups 9, 10 and a Siemens star. The lateral dimensions were ≤ 980 nm. During ion beam milling, the beam parameters current and the number of scan repetitions were varied to investigate their influence on the structuring result. Subsequently, SEM measurements were conducted to characterize the milled nanostructures. Different lateral resolutions and depths of the pattern and effects like redeposition or the proximity effect were observed for the nanostructures depending on the coating and processing conditions. Lateral feature sizes down to 60 nm could be realized. In conclusion, the gained results approved FIB writing as a suitable technique to manufacture highly precise nanostructures into surface coatings for molding.

Zusammenfassung

Die Herstellung von dreidimensionalen Schaltungsträgern aus spritzgegossenen Thermoplasten, welche mittels Laserdirektstrukturierung und anschließender außenstromloser selektiver Metallisierung funktionalisiert werden, ist mittlerweile Stand der Technik. Bei erhöhter thermischer und/oder mechanischer Belastung z.B. durch Steigerung der elektrischen Leistungsdichte, stoßen Thermoplaste jedoch an ihre Grenzen. Hier bieten keramische Substratmaterialien klare Vorteile. Die Herstellung von solchen keramischen Schaltungsträgern mittels laserinduzierter Direktmetallisierung wurde erfolgreich realisiert. Hierfür wurden zwei Unterschiedliche Varianten an Al2O3-Keramiken untersucht. In der ersten Variante erfolgte das Sintern der Al2O3-Keramiken in H2-Atmosphäre, in Variante 2 wurden die Al2O3-Keramiken mit Cr2O3 dotiert und an Luft gesintert. Anschließend erfolgte für beide Varianten eine Laserstrukturierung mit darauffolgender außenstromloser Metallisierung. Somit ließen sich 3D-Schaltungsträger mit hoher thermischer Belastbarkeit, einer geringen Wärmeausdehnung und einer guten elektrischen Isolation herstellen. Die abgeschiedenen Metallschichten zeigten vergleichbare und zum Teil bessere Eigenschaften als solche auf klassischen thermoplastischen 3D-Schaltungsträgern. Three-dimensional interconnect devices based on injection molded thermoplastics, which are laser direct structured and subsequently plated via selective electroless metallization are meanwhile the state-of-the-art. With increased thermal and or mechanical load, e.g. at high electric power densities, ceramic materials show superior properties compared to thermoplastic materials. The fabrication of ceramic interconnect devices based on laser-induced metallization has been successfully demonstrated. Therefore, Al2O3 has been used, which was either sintered in H2-atmosphere or doped with Cr2O3 and sintered in air, followed by laser structuring and electroless metallization. Thereby, 3D interconnect devices with high thermal robustness, low thermal expansion and good electric isolation could be manufactured. The metallization on ceramics showed similar or even better properties than on conventional thermoplastic substrates.

Zusammenfassung

In this paper, we introduce an improved, three-dimensional coplanar line structure manufactured using Laser Direct Structuring (LDS) technology. The low-loss and robust against tolerance transmission line structure can be used for building conformal millimeter wave (mmWave) sensor applications as e.g. automotive radar.

Zusammenfassung

Drehwinkelsensoren werden in zahlreichen Anwendungen u.a. zur Positionserfassung benötigt. Ein neuer Ansatz ermöglicht hoch miniaturisierte optische Drehwinkelsensoren in der neben dem Drehwinkel auch zusätzliche Sensorik sowie ein frei programmierbarer Mikrocontroller integriert sind. Dadurch können direkt im Sensor Abgleich- und Diagnosefunktionen implementiert und Zusatzinformationen wie Drehzahl und Beschleunigungen abgeleitet werden. Ferner erfasst und verarbeitet der Mikrocontroller die Messwerte, wie Gehäuse- und Wellenvibrationen und die Umgebungstemperatur. Dadurch lässt sich mit Hilfe von Kompensationsalgorithmen auf den Betriebszustand des Sensors schließen. Der Drehwinkelsensor soll eine Auflösung von 15 Bit bei einem Bauraum von nur rund einem Kubikzentimeter erreichen.

Zusammenfassung

Inkjet-printing of nanoparticle inks allows the integration of electrodes directly into 2.5D structures, like microfluidic chambers. Sensing applications can additionally benefit from the nanoporous morphology of the printed electrodes. The presented results demonstrate that the high effective surface of the porous electrode is suitable for functionalization by immobilizing DNA and determining the DNA density. It is envisioned that the method facilitates the integration of porous electrodes into microfluidic systems.

Zusammenfassung

Some of the most important quality assets of Laser Direct Structured Molded Interconnect Devices (LDS-MID) are their efficiency and reliability. In order to identify the production parameters and materials, which yield devices with superior performance, the following studies were conducted. Initially, a Design of Experiments (DoE) allowed making a qualitative and quantitative statement about conductor track defects and their causes as well as about the efficiency due to the electrical conductivity of the tracks. These results were used to suggest certain combinations of substrate material and metal layer to improve the production quality of MIDs. Such findings guide the path towards high-performance LDS-MIDs, which can be operated under harsh conditions. Along this line, specimens of 16 different factor-combinations were subjected to a temperature shock test, whereby the resistance value of the conductor tracks could be continuously measured, using a four-wire measurement. The latter allowed a precise detection of conductor cracks or solder joint failures. It appeared that most of the chosen factorcombinations showed an almost constant electrical resistance during the temperature shock tests. However, the type of thermoplastic substrate material, as well as the heat input by the soldering process, could be identified as the factors with the most significant influence on reliability and electrical conductivity.

Zusammenfassung

Increasing demands regarding reliability of mechatronic systems and the aim for miniaturization require new materials and processes for the 3D mechatronic interconnect devices (3DMID) technology to fulfill those demands. For the first time, this paper demonstrates the solderability of a new material class for 3D-MID applications, down to the SMD component size 01005. Instead of standard and state-of-the-art thermoplastic materials such as polyamide or high-performance thermoplastic materials commercial injection moldable thermoset resins were used. They were selectively metallized by laser structuring and electroless plating. Different laser parameters for structuring of two different substrate materials were investigated. SMD resistor components with the size 0805, 0402, 0201 and 01005 were used to evaluate material solderability on stencil printed solder pads. Specimen were analyzed using optical analysis, metallographic examination and shear tests. The results show that component size and laser energy have the most significant effect on shear strength and defects. Eligibility for common soldering processes in electronics packaging was proven. Additionally, soldering results between convection soldering and vapor phase soldering were compared, showing higher shear forces for samples soldered in the convection oven. Based on the results the tested injection moldable thermoset resins are suited as circuit carrier material in electronic packaging.

Zusammenfassung

The potential of 3D-MID technologies for Space applications is investigated within the ESA Artes 5.1 programme. Several test samples and test vehicles have been built to demonstrate assembly techniques, weight gain and have been characterised to achieve TRL 5. In this paper possible assembly processes for 3D-MID are shown and the results of environmental testing are presented.

Zusammenfassung

Radio frequency reflectometry is widely used in non-destructive characterization of various materials and can also be applied to automatic impedance matching systems in telecommunication devices. Here, a novel, low cost, software defined approach for measuring the reflection coefficient without using mixers or power detectors is proposed, enabled by using under-sampling down-conversion with an analog-digital-converter. Minimizing the analog part of the system removes possible error sources and a modular design allows application in different fields as well as an implementation as an integrated circuit. Computer simulations as well as measurement results on a printed circuit board setup for a system frequency of 400 MHz are presented, permitting extrapolation to other ultra-high frequencies.

Zusammenfassung

As miniaturization is an important aspect in all areas of circuit technology, highest demands are placed on optimum space utilization and the reduction of material and production cost. MID (Molded Interconnect Devices or Mechatronic Integrated Devices) are already broadly used in consumer electronics antennas, automation, automotive and medical technology, however MID have unexploited potential for high-frequency and fast-paced systems in particular. This work will present the design and manufacturing process of MID for RF (Radio Frequency) applications and provide RF relevant characteristics for substrate materials used in the LPKF-LDS (r)(Laser Direct Structuring) process. Furthermore, characteristics of the circuits on the injection molded plastic part, optimization of vias and interconnection geometries for hybrid assemblies will be discussed

Zusammenfassung

In the past decades, research in the field of photonics has rapidly increased. Different photonic applications have been extensively investigated and are about to be ready for commercialization. However, photonics packaging is still one major challenge preventing the commercial deployment of photonic systems. Compared to electronics packaging, photonic packaging poses additional challenges. It contains a number of competing requirements, for which compromises are necessary. For example, thermal management of photonic systems requires not only efficient heat dissipation, but also the reduction of temperature gradients. Certain material combinations that improve the heat dissipation increase the thermal cross-talk between components, resulting in temperature gradients in the photonic IC. Therefore, when selecting packaging materials, compromises between efficient heat dissipation and the reduction of temperature gradients must be made. This work uses a combination of Design of Experiments (DoE) and FEM simulations to analyze a large parameter space in a time and cost efficient manner. The optimal material combination is determined with FEM-DoE, so that targeted experiments can be carried out near this optimal working point. This reduces not only development costs, but also shortens decision times. In the FEM-DoE, each "experiment" refers to a simulation performed with a different set of input variables. The FEM-DoE results are then evaluated to derive a mathematical equation providing information about the influence of the different input factors on the output responses.

Zusammenfassung

A novel optical incremental and absolute encoder based on an opto-ASIC and an encoder disk carrying micro manufactured structures is presented. The opto-ASIC contains a ring of photodiodes that represents the encryption of the encoder. It also includes the analog signal conditioning, the signal acquisition, a control of the light source as well as the digital position processing. A laser diode is assembled in the center on top of the opto-ASIC together with a micro manufactured polymer lens. The latter is fabricated using ultra precision machining. The encoder disk was fabricated using micro injection molding and contains microstructures forming a Blaze grating. This way a 10 bit optical encoder with a form factor of 1cm³ was realized.

Zusammenfassung

Faster Product Lifecycles make investments in machines for micro assembly riskier. Therefore, reconfigurable manufacturing systems gain more and more attention. But most customers are uncertain, if a reconfigurable manufacturing system can fulfil their needs. In this paper a novel approach for a product development method is given, which incorporates lean development methods for agile processes and focus on the conceptual design phase to overcome the customers uncertainty in the development process. For this a general representation of the conceptual design is established and validated by a team of experts.

Zusammenfassung

Digital non-contact-printing technologies such as inkjet or Aerosol Jet are becoming more and more interesting for the manufacturing of electronic components due to their benefits such as easy variation of printing layouts, short process chains without masks, large variety of usable substrates and inks - frequently based on nano metals - and a certain 3D capability. In this contribution options are discussed to sinter nano metal inks such as Ag, Au, and CuNi inks at low temperature, thus enabling the use of temperature sensitive polymer substrates like PC, PS, or PMMA. This includes the addition of chemical agents as well as light-based sintering methods such as photonic curing or laser sintering. Finally some application examples are presented.

Zusammenfassung

A novel process for laser induced selective metallization of alumina substrates is presented. Alumina substrates are provided by ceramic injection molding, whereby three-dimensional shaping of the ceramic parts is feasible. Laser patterning activates the surface and enables fully additive metal deposition by electroless plating. As the focus diameter of the used picosecond pulsed laser is about 10 μm very fine metal lines can be achieved. The metal layer thickness is comparable to conducting paths fabricated by LPKF-LDS technology onthermoplastic substrates, whereas the adhesion is significantly stronger and promises high reliability. The low metal surface roughness enables the assembly of electronic components on the ceramic devices.

Zusammenfassung

Micro lens arrays (MLA) are broadly used in a multitude of optical applications, whereas increasingly extended areas need to be structured. Furthermore, growing quantities of microoptical components require micro- and nano-replication techniques, such as injection moulding and injection compression moulding. Therefore, ultra-precision milling strategies for manufacturing of mould inserts have been evaluated regarding applicability, surface quality and processing time. Different milling strategies were investigated regarding processing time and resulting surface quality. Single flute diamond milling tools were used to mill the mould cavities in nickel-phosphorus (NiP) coating deposited on tooling steel. The experiments were conducted on a 5-axis ultra-precision milling machine and qualitative results regarding observed effects of the different strategies were evaluated. The achieved surface qualities were analysed and quantified using white light interferometry. Methods of ring, radial or spiral milling strategies showed different failure modes and shortcomings such as stepping, pin residues or long processing times. Using a method, where a specifically designed milling tool was immersed in a single step into the bulk material, best results were achieved and the processing time for each lens was reduced to a minimum. The quality of the MLA could be further increased by immersing the milling tool in a defined angle. It was observed, that the centering and radius of the diamond of the milling tool was a major factor. Conclusively, the results show that high quality tooling in combination with the applied milling strategy enables significant improvements in quality and costs.

Zusammenfassung

The fabrication of microstructured polymer optics enables a multitude of new options in the design of technical optics. However, challenges arise along the varying process chains of mold insert fabrication, integration into molding tools, replication by means of injection compression molding and metrology. In order to study the effects, diffractive optical elements (DOE) and micro lens arrays (MLA) are fabricated using two different process chains. DOEs are fabricated using a laser direct writing (LDW) based mold insert fabrication. The MLA mold insert is produced using ultraprecision milling (UP-milling). Both optical parts are replicated using injection compression molding. The occurring effects are discussed and the results show, that with complete process control high quality microstructured polymer optical parts can be produced and characterized.

Zusammenfassung

Due to the functional integration potential and the excellent design freedom, molded interconnect devices (MID) are becoming more and more attractive for several fields, such as consumer electronics, automotive and lighting technologies. In this context, the need for better reliability, especially for the solid state lighting, has significantly increased recently. Thermal management impacts not only the efficiency but also the reliability and the color stability of LED arrays, where LEDs are subjected to mutual interferences. Thus, the use of highly filled and thermally conductive thermoplastics appears very appealing.In light of this fact, an experimental and computational study, with focus on the influence of the substrate material and heat dissipation concepts on the thermal management of low- and high-power LEDs on MID, is presented in this paper. The accuracy of the implemented Finite Elements Analysis (FEA) is also examined in this work and used to forecast the reliability of a 3D-MID lighting module.

Zusammenfassung

Winkelmessung auf engstem Raum war bisher eine kaum lösbare Aufgabe. Insbesondere, wenn ein optisches Verfahren angewendet werden soll und eine hohe Auflösung benötigt wird, ist bisher keine zufriedenstellende Lösung zu finden. Hahn-Schickard hat in Zusammenarbeit mit dem IMS Chips einen neuen Ansatz zur Lösung dieser Aufgabe gefunden.

Zusammenfassung

Micro technology deals with the fabrication of structures in the length scale between 0.1 and 1000 µm and can be considered as an important enabler for micro systems such as miniaturized sensors. Recent advances in micro manufacturing will be demonstrated by examples of microfluidic, optical and mechatronic devices. In the area of microfluidics, the fabrication of centrifugal microfluidics for automated analytics and diagnostics via injection compression molding is addressed. Manufacturing of optical components via micro injection molding and precision assembly of those components will be presented with respect to optical sensors. Molded interconnect devices serve as an example for the manufacturing of mechatronic devices. Apart from manufacturing technologies, the application of simulation methods for the assessment of manufacturability and reliability of the devices will be discussed.

Zusammenfassung

Molded Interconnect Device (MID) Technology features excellent design freedom and great potential for functional integration for applications in indoor lighting. Spatial arrangement of LEDs and intelligent control elements enable highly efficient, situation aware lighting concepts with attractive design. Even more than in PCB based LED lighting technologies, there are significant degrees of freedom for improved thermal management when designing and manufacturing an MID. In this work, measures suitable for thermal management of MID for lighting applications manufactured with LPKF-LDS® technology are identified and compared. Focus is on design for thermal management and application of recently developed high thermal conductivity polymers. To compare the effects of the different measures, simulations are performed with a range of combinations of individual measures for thermal management. The simulation results of the individual combinations are evaluated using design of experiments statistical methods. Low cost measures relying on design for thermal management are compared to measures implying higher manufacturing costs and to substrates manufactured from high thermal conductivity polymer compounds.

Zusammenfassung

Reliability aspects are crucial for the success of every technology in industrial application. Regarding interconnect devices, several methods are applied to evaluate reliability of conductor paths like accelerated environmental tests. Especially Moulded Interconnect Devices (MID) which enable versatile applications with 3D circuitry on 3D shaped injection moulded thermoplastic parts are often under particular stress, e.g. as component of a housing. In this paper a new test method for evaluating the flexural fatigue strength of conductor paths produced by the laser based LPKF-LDS® technology is presented.

Zusammenfassung

Digital non-contact-printing technologies e.g. inkjet or Aerosol Jet® are becoming more and more interesting for the manufacturing of electronic components due to their benefits such as easy variation of printing layouts, short process chains without masks, large variety of usable substrates and inks - frequently based on nanomaterials - and a certain 3D capability. In this paper printed sensors for e.g. temperature, strain, intrusion, humidity, or magnetic fields fabricated by inkjet or Aerosol Jet® technology and characterization results are described.

Zusammenfassung

A newly developed process for selective metallization of injection moulded ceramic substrates without additional additives for laser activation is presented. Ceramic substrates were manufactured by hot-pressing technique or by ceramic injection moulding (CIM) with subsequent debindering and sintering. Then substrate surfaces are activated by laser patterning for subsequent electroless plating with copper, nickel and gold. Due to the small-sized laser spot of the pico second laser used, very fine metal line structures can be obtained. Both the roughness as well as the layer thickness of the metal layers are similar to those obtained by LPKF-LDS technology on thermoplastics whereas the adhesion strength tends to be higher on alumina substrates.

Zusammenfassung

Today's printed electronics are mainly focused on producing sensors on thin, flexible, smooth foils, which limits their use on 2D applications. Within this study we report on the design of inkjet printed capacitive touch and humidity sensors on thermoplastic substrates, to fabricate printed functional structures on injection molded 3D components. Both sensors are based on printed differential interdigital capacitors (IDC) made of silver ink and a printed sensitive layer. Reproducible results and low hysteresis were achieved, proving the concept to be able to improve sensitivity and to reduce drift effects due to temperature as well as moisture absorption by the substrate.

Zusammenfassung

This paper focuses on packaging of thin film thermoelectric generators (TEG) for energy harvesting applications in sensor nodes for the internet of things (IoT). The TEGs have to be robust against mechanical stress caused by the assembly and packaging process steps and the mismatch of the coefficients of thermal expansion of the used materials. In this work, the mechanical stability of TEGs was evaluated by using a shear force test apparatus and a four line bending test. Furthermore the influence of underfill and stress decoupling thermal adhesives on the mechanical performance was investigated. It could be shown that underfill between the two substrates improves the shear force stability of the investigated thermoelectric generators. During mechanical tests the internal electrical resistance of the modules was monitored. It was observed, that the electrical shutdown coincides with the mechanical shutdown of the generator. By using selected thermal adhesives with and without underfill a sufficient robustness of the thermoelectric generator against typical warpage as known from a standard molded land grid array (LGA) sensor package was achieved.

Zusammenfassung

Laser based patterning combined with selective metallization of 3D devices show high capability for various miniaturized applications. With a minimized spot size laser technologies provide a very fine patterning tool and are very flexible concerning the 3D circuitry by simple adapting the laser processing parameters. As new application fileds with e.g. high thermal requirements are coming up, substrate materials such as thermosets and ceramics get more and more important. In this paper laser based patterning techniques for fabrication of 3D conductor paths on different substrate materials are described.

Zusammenfassung

Printed electronics provides new perspectives for the manufacturing of highly innovative low cost polymer based packages. Conventional printing technologes such as screen printing, offset printing, inkjet printing and the Aerosol Jet process meet the requirements of miniaturised systems. Because of a variety of functional inks passive devices such as resistors and capacitors as well as acitve devices such as transistors can be fabricated. The new promising field of appication for printed electronics is the fabrication of 3D polymer packages by directly printing on 3D-substrates. This paper presents first print studies on 3D-substrates using inkjet printing as well as Aerosol Jet process. Conductive silver tracks were printed via inkjet on a 3D thermoplastic substrate topology and via Aerosol Jet process for chip interconnection as well as in a cavity of an epoxy laminated substrate (FR4). Nanoparticle-based silver inks were used for both printing processes.

Zusammenfassung

MID (Moulded Interconnect Devices) bieten als spritzgießtechnisch hergestellte Kunst-stoffbauteile den Vorteil, neben der Gehäusefunktion auch elektrische Verdrah-tungstrukturen zu integrieren, welche durch eine selektive Metallbeschichtung erzeugt werden können. MID-Technologien bieten daher aufgrund der geometrischen Freiheiten von spritzgegossenenen Kunststoffteilen hervorragende Möglichkeiten zum Aufbau von mechatronischen Systemen mit integrierter Sensorik. Die MID-Technologie eignet sich hervorragend zum Aufbau neuartiger Module für ein interaktives Braille-Display, wel-ches sehbehinderten und blinden Menschen den Zugang zu graphischen Informationen und Windowsanwendungen sowie die Nutzung des Internets in vollem Umfang ermög-licht. Die ersten MID basierten Braille-Module wurden in einer Kleinserie mit einem semi-additiven Laserverfahren (LSA-Technik) am HSG-IMAT/IZFM hergestellt. In Zu-sammenarbeit mit der Metec AG wurden die Module im BMWi geförderten Projekt HyperBraille® unter anderem im Hinblick auf Miniaturisierung weiterentwickelt. Die Module der zweiten Generation haben eine verringerte Bauhöhe und werden in LPKF-LDS®-Technik hergestellt. Die Vorteile der LPKF-LDS®-Technik gegenüber dem semi-additiven-Laserverfahren liegen in einer kürzeren Prozesskette, kürzerer Laserbe-arbeitungszeit sowie in einer größeren 3D-Fähigkeit.

Zusammenfassung

Im Beitrag wird eine grundlegend neue Aufbau- und Verbindungstechnik für das Packaging von Silizium-Chips mit geringen Anschlusszahlen vorgestellt, welche die vielseitigen Möglichkeiten der MID-Techniken (Molded Interconnect Device) nutzt. Die nackten Silizium-Chips werden dabei in Einlegetechnik über konventionellen Spritzguss mit einem laseraktivierbaren LCP (Liquid Crystal Polymer)-Thermoplast umspritzt. Spritzguss-Simulationen wurden durchgeführt, um die Schmelze in der Kavität so zu lenken, dass der empfindliche Silizium-Chip nicht beschädigt und nur durch die Druckverteilung in seiner exakten Position gehalten wird. Mit dem LPKF-LDS®-Prozess wird auf das Kunststoffpackage anschließend mittels Laser das elektrische Leiterbahnlayout strukturiert sowie die Bohrungen zu den elektrischen Kontaktflächen des Silizium-Chips erzeugt. In einem außenstromlosen Metallbeschichtungsprozess werden die laserstrukturierten Bereiche sowie die Bohrungen mit Kupfer, Nickel und Gold beschichtet. Somit kann die Kontaktierung und Verdrahtung des Silizium-Chips direkt auf dem Package realisiert werden, so dass auf klassische Aufbau- und Verbindungstechniken wie z.B. Flipchip- oder Drahtbondtechnik verzichtet werden kann.

Zusammenfassung

Die selektive und haftfeste Metallisierung von Hochleistungsthermoplasten wie beispielsweise PPS oder PEEK für mechatronische Systeme und Mikrosysteme in z.B. Medizintechnik, Lebensmitteltechnologie und chemischer Prozesstechnik stellt nach wie vor eine Herausforderung dar. Im Beitrag wird daher ein neues Verfahren zur Herstellung von Molded Interconnected Devices (MID) aus Hochleistungsthermoplasten mit feinen Leiterstrukturen vorgestellt. Dabei wird in einem ersten Schritt auf einer dünnen Trägerfolie aus Kupfer eine Hotmelt-Maske mittels Inkjet-Verfahren gedruckt. Anschließend erfolgt die galvanische Abscheidung eines Schichtstapels aus Gold, Nickel und Kupfer. Nach Strippen der Hotmelt-Maske wird die vorbereitete Trägerfolie mit einem Hochleistungsthermoplasten hinterspritzt. Abschließend erfolgt die Entfernung der Trägerfolie in einem Ätzprozess.

Zusammenfassung

In this paper we report an alternative sintering method for conductive silver tracks by UV radiation. The silver patterns have been obtained by inkjet printing from a commercially available silver nanoparticle ink. Different polymer materials such as polyimide, polycarbonate and liquid crystal polymer have been used as substrate materials. UV-curing resulted in highly conductive patterns with resistivities as low as four times that of bulk silver. The choice of substrate material has shown to greatly influence the achievable conductivity values. Furthermore it was demonstrated that UV-sintering resulted in lower substrate temperature as compared to thermal sintering to get similar resistance values.

Zusammenfassung

Drucktechniken bieten vielfältige Möglichkeiten zum additiven Aufbau und zur Integration von funktionalen Strukturen in Mikro- und Nanosystemen. Passive und aktive Bauelemente lassen sich auf unterschiedlichen Substraten mittels des neuartigen Aerosol Jet Verfahrens aufbauen. In diesem Beitrags wird beispielhaft auf mittels Aerosol Jet Technologie hergestellte Widerstände, Temperatursensoren, Kondensatoren und Dünnfilmtransistoren eingegangen.

Zusammenfassung

Drucktechniken wie das neuartige Aerosol Jet®-Verfahren bieten vielfältige Möglichkeiten zum additiven Aufbau von funktionalen Strukturen aus Leiterbahnen, Bauelementen sowie verschiedenen Sensorelementen auf polymerbasierten Substraten. Mit dem Aerosol Jet®-Verfahren wurden Temperatur- und Dehnungssensoren aus nanoskaligen Silbertinten auf thermoplastischen Substraten aufgebaut und charakterisiert.

Zusammenfassung

MID (Moulded Interconnect Devices) technology offer a high potential for miniaturization of multifunctional 3D plastic devices in medical and communication technology, automotive applications, mechanical engineering and automation. The semi additive laser MID technology is currently used for the fabrication of novel modules for a graphic capable interactive Braille display for blind people. 10 Braille pins are assembled in each module which are driven by piezo actuators at a voltage of 200 V. Furthermore in each module a touch sensor is integrated which enables blind people the mouse click function for internet using. The electronic circuit for controlling the actuators and the touch sensor requires two bare die ASICs and several SMD components which are assembled by isotropic conductive adhesive, aluminium wire bonding and encapsulation. 720 single modules are needed for a Braille display unit.

Zusammenfassung

Am HSG-IMAT wurde ein neuartiges Dosierkonzept zur kontaminationsfreien Handhabung von Flüssigkeiten erarbeitet. Es zeichnet sich durch eine hohe Fördergenauigkeit und einen sehr niedrigen Energieverbrauch aus. Experimentelle Untersuchungen an einem Seifenspender-Demonstrator bestätigen das große Potenzial des Konzepts. Mittels numerischer FEM-Simulation wurde der elektromagnetische Antrieb des Seifenspenders nach funktionellen und fertigungstechnischen Gesichtspunkten optimiert. Außerdem wurde für das fluidische System des Seifenspenders ein elektrisches Analogmodell erstellt. Die mittels Netzwerkanalyse erzielten Ergebnisse zeigen eine hervorragende Übereinstimmung mit den experimentellen Messwerten.

Zusammenfassung

IZFM und HSG-IMAT beschäftigen sich seit einigen Jahren mit der Herstellung hochpräziser Bauteile aus Kunststoff, die als Funktionselemente in Mikrosystemen oder mechatronischen Systemen zum Einsatz kommen. Das eigentliche Kunststoffelement wird bei diesen Anwendungen nicht nur als Gehäuse- oder Verbindungselement eingesetzt, sondern erfüllt vielmehr noch weitere wichtige Grundfunktionen im Gesamtsystem. Das Anwendungsspektrum sowie die Funktionalität dieser meist hochpräzisen und häufig auch sehr kleinen Bauteile sind dabei breit gefächert. Mikrofluidische, medizintechnische und optische Bauelemente sind ebenso vertreten, wie komplexe Spritzgießteile für Moulded Interconnect Devices (MID). Mit Hilfe der verschiedenen MID-Techniken werden aus Kunststoffbauteilen komplexe dreidimensionale elektrische Schaltungsträger und damit mechatronische Systeme mit sehr hoher Integrations- und Funktionsdichte.

Zusammenfassung

The ongoing trend of miniaturisation in the field of micro mechatronic systems poses new challenges for fabricating highly innovative polymer based packages. Printing technologies such as screen printing, inkjet and pad printing as well as the novel Aerosol Jet® process provide versatile possibilities to meet the requirements of miniaturised systems. These additive technologies can be used for the fabrication of structured functional coatings on polymer packages. Passive devices such as resistors and capacitors as well as multi-layer conductive patterns and sensor elements can be deposited on various substrates. Within this paper the results of the latest print studies at HSG-IMAT and IZFM will be presented. This includes printing of a carbon based resistor material as well as printing of highly conductive silver ink and a polymer based suspension with relatively low conductivity. As printing technologies both aerosol jet printing and screen printing have been applied on FR4 substrates and thermoplastic MID substrates. Furthermore, first environmental testing has been done to investigate environmental effects on the behaviour of the printed resistors.

Zusammenfassung

Drucktechniken bieten vielfältige Möglichkeiten zum additiven Aufbau von funktionalen Strukturen aus Widerstandsmaterialien, ein- und mehrlagigen Leiterbahnstrukturen sowie verschiedenen Sensorelementen auf polymerbasierten Substraten. Dadurch ergeben sich neue Verfahren zur Miniaturisierung, Erhöhung der Funktionsdichte und Integration von sensorischen Elementen in kunststoffbasierten mikromechatronischen Baugruppen.

Zusammenfassung

The electrochemical milling with ultra short voltage pulses (ECF) displays an important process in micromachining of hard materials. Machining a workpiece with conventional milling the removal takes place by shape cutting. Therefore mechanical forces are applied to tool and workpiece. In contrast, using electrochemical milling, the material removal occurs by an electrochemical reaction. Therefore the workpiece as well as the tool are submerged into an electrolyte and the surface of the workpiece is etched by a galvanic current. Hereby the so called working distance is formed between tool and workpiece, which goes linear with the pulse amplitude and pulse on time in a first approximation. As a result, there are no mechanical forces applied to the tool. This allows the use of very thin tools. To achieve the highest precision with this technique, it is necessary to manufacture very precise tools and to very their shape and dimensions. In addition the use of rotating tools could be a promising strategy to speed up the ECF process and reduce the roughness. Therefore we introduce a method to produce very thin rotation-symmetric tools with high precision using the ECF technique. While the tool rotates the diameter is reduced by a one sided removal of material similar to machining with a turning lathe. To verify the shape and the dimensions of these tools a commercial laser measuring system for tool setting and breakage control was integrated into the ECF machine. Algorithms to determine the tool diameter and the toolshape are installed. Further algorithms have to be developed to characterize more details of the tool like tilt and run-out error.

Zusammenfassung

The electrochemical milling with ultra short voltage pulses (ECF) displays an important process in micromachining of hard materials. Machining a workpiece with conventional milling the removal takes place by shape cutting. Therefore mechanical forces are applied to tool and workpiece. In contrast, using electrochemical milling, the material removal occurs by an electrochemical reaction. Therefore the workpiece as well as the tool are submerged into an electrolyte and the surface of the workpiece is etched by a galvanic current. Hereby the so called working distance is formed between tool and workpiece, which goes linear with the pulse amplitude and pulse on time in a first approximation. As a result, there are no mechanical forces applied to the tool. This allows the use of very thin tools. To achieve the highest precision with this technique, it is necessary to manufacture very precise tools and to very their shape and dimensions. In addition the use of rotating tools could be a promising strategy to speed up the ECF process and reduce the roughness. Therefore we introduce a method to produce very thin rotation-symmetric tools with high precision using the ECF technique. While the tool rotates the diameter is reduced by a one sided removal of material similar to machining with a turning lathe. To verify the shape and the dimensions of these tools a commercial laser measuring system for tool setting and breakage control was integrated into the ECF machine. Algorithms to determine the tool diameter and the toolshape are installed. Further algorithms have to be developed to characterize more details of the tool like tilt and run-out error.

Zusammenfassung

The continual trend of miniaturization and increasing complexity in the field of microelectronic devices pose a challenge for today's manufacturing technology. The novel Maskless Mesoscale Material Deposition (M3D) manufacturing technology offers the potential for printing superfine circuitry as well as for the building up of multi-layer systems. Therefore it could be an interesting technology to meet the requirements of miniaturized systems. The M3D process depends on aerosol formation and uses aerodynamic focusing of aerosol streams for a high resolution deposition of cooloidal suspensions and liquid raw material. Since M3D is a contactless and maskless Direct Write Technolgy, it also offers new possibilities for 3D devices. This paper will report on first results of depositing conductive and non conductive materials onto glass substrates as well as onto typical MID (Moulded Interconnect Devices) substrates. Furthermore it will present first mult-layer systems that have been fabricated using the M3D technology.

Zusammenfassung

Mit der zunehmenden Verbreitung von Computer-Anwendungen wächst bei blinden oder stark sehbehinderten Menschen das Bedürfnis, an den heutigen Formen der Kommunikation, die sehenden Menschen insbesondere mit Hilfe von PCs zur Verfügung stehen, teilnehmen und weitgehend uneingeschränkt mit Computern arbeiten zu können. Dies beinhaltet vor allem den Zugang zu graphischen Informationen und insbesondere die volle Nutzung des Internet. Für die elektronische Darstellung der Braille-Symbole der Blindenschrift gibt es bereits so genannte Braille-Zeilen, die das zeilenweise Buchstaben-Lesen gestatten. Um grafische Informationen darzustellen und im Bild die Maus-Klick-Funktion zu ermöglichen wurde in einem BMBF-Verbundvorhaben ein erster Demonstrator eines interaktiven graphikfähigen Braille-Displays erarbeitet (Bild1), welches blinden Menschen die Nutzung sämtlicher Funktionen moderner Windows-PCs erlaubt. Der Demonstrator besteht aus 36 einzelnen Modulen mit je 10 schaltbaren Stiften (Bild 2), wobei die Module in semiadditiver Laser-MID-Technik hergestellt sind. Zur Realisierung der Maus-Klick-Funktion ist in jedem MID-Modul zwischen den Stiften eine kapazitiv ausgelesene Touchsensorstruktur integriert (Bild 3), wodurch der jeweilige Ort der Finger auf dem Display detektiert werden kann. Die auf dem MID integrierte Schaltung zum Betrieb der Module besteht aus diversen SMD-Bauelementen, zwei ASICs als ungehäuste Si-Chips sowie 10 piezoelektrischen Biegewandlern. Die Piezoaktoren werden über den HV-ASIC mit einer Spannung von 200 V angesteuert und bewegen die Stifte. Der Mixed-Signal-ASIC fungiert als Auswahlschaltung und digitalisiert das Signal des Touchsensors. Die Si-Chips werden geklebt, mittels Al-Drahtbonden elektrisch kontaktiert und anschließend vergossen. Die SMD-Bauelemente sowie die Piezoaktoren werden mittels Leitkleben aufgebaut. Derzeit werden erste Displays mit insgesamt je 720 Modulen angefertigt.

Zusammenfassung

Electrochemical machining with ultra short voltage pulses (ECF) is an innovative technique to machine electrochemically active materials at micrometer feature size, particularly hard materials like stainless steel. Because ECF is an electrochemical process the workpiece as well as the tool are submerged in an appropriate electrolyte. The workpiece is electrochemically etched by a galvanic current. Therefore no mechanical forces, no thermal load and no tool wear occurs. Due to the use of short voltage pulses in the range of 10-200 ns the electrochemical process is confined to a small area around the tool. The ability to manufacture microstructures even in stainless steel makes ECF the ideal technique for the processing of micro moulds. For a higher through-put and a reasonable size of the moulds it is useful to manufacture the micro moulds in two steps. First conventional high precision milling is used to manufacture the main structure. Afterwards the structure is finished by the ECF process. Since these two steps are carried out on two different machines, the workpiece has to be aligned in the ECF machine after the milling process. Using a matching strategy alignment errors like rotation to the xy-plane, errors in scaling of the length of the axis and translation in the xy-plane can be corrected automatically by transforming the CAD/CAM data in a way that they match the two co-ordinate systems. It is shown by test-pattern that this strategy works very accurately. There is almost no mismatch between the HSC pre-milled structure and the ECF added microstructure in the different examples shown here. This investigation shows that hybrid tooling with ECF is a time saving approach to add microstructures with the ECF-process into pre-milled moulds. Therefore hybrid tooling has a high potential to become one of the leading techniques to manufacture cavities, e.g. for micro moulds in stainless steel.

Zusammenfassung

Moulded Interconnect Devices (MIDs) sind spritzgegossene Kunststoff-Formteile mit dreidimensionalen Gestaltungsfreiheit, die selektiv mit einer Metallbeschichtung als Leiterbild versehen werden. HSG-IMAT und IZFM beschäftigen sich seit 1998 mit Aufbau- und Verbindungstechniken für Mikrosysteme auf Basis von MID-Techniken. Seit Beginn wird dabei ebenfalls die Eignung dieser innovativen Technik für die Integration von sensorischen und aktorischen Funktionen untersucht. Kapazitive Wirkprinzipien für Sensoren zeichnen sich durch hohe Auflösung, schnelle Ansprechzeiten, gute Stabilität und geringen Energiebedarf aus. Die Elektrodenstrukturen zur kapazitiven Auslese lassen sich besonders mit Hilfe der MID-Technik einfach herstellen. Die am HSG-IMAT und IZFM realiserten Sensorkonzepte basieren auf Differential-Kondensator-Anordnungen, bei welchen die durch die Messgröße veränderliche Kapazität bezüglich einer Referenzkapazität gemessen wird. Mit Verwendung der MID-Technik lässt sich durch Integration von Gehäuse, sensitiver Elektrodenstruktur und Elektronik ein hoher Miniaturisierunggrad des Sensorsystems erreichen. Im Folgenden werden einige der bisher realisierten Sensorkonzepte vorgestellt.

Zusammenfassung

Electrochemical milling with ultra short voltage pulses (ECF) is an innovative technique to machine electrochemically active materials at micrometer feature size, especially very hard materials like steel. The movement of the tool is similiar to conventional milling, although it does not rotate. Therefore 3D-forming of the workpiece is possible. the surface of the workpiece is etched by galvanic current. Due to this neither mechanical forces nor thermal loads are applied to workpiece or tool. The ability to manufacture hard materials like stainless steel at micrometer feature size makes ECF the ideal technique for processing micro moulds. When manufacturing moulds large differences in machining speed and quality of the surface occur. So far possible explanations for this were supposed differences between the machinability of grain boundaries and interior of the grains. But experiments showed no significant influence. Furthermore the dependence of the tool diameter on the working distance was determined. Experiments showed a decreasing working distance with increasing tool diameter. This phenomenon could also be explained theoretically. Finally the influence of the grade of hardness on the EFC process is investigated at the tool steel M 340.

Zusammenfassung

Through miniaturisation and 3D capability moulded interconnect devices (MID) offer great opportunities for various applications in a broad industrial field. Especially, when appliying the laser-direct-strcturing process of the company LPKF (LPKF-LDS process) fine conductors can be fabricated on thermoplastic substrates. A main criterion for the industrial application is the adhesive strength of the conductors. As for LDS MID there is currently no suitable test method for directly determining the adhesive strength of conductors. Therefore, a measuring device consisting of a sensor and a peel of unit has been developed at HSG-IMAT. It has been used to investigage a measuring principle utilising a peel off chisel for adhesion determination. Promising and repeatable results have been obtained by testing conductors on thermoplastic substrates.

Zusammenfassung

We report on an innovative low cost concept for micromechanical capacitive inclination sensors based on MID-technology (Moulded Interconnect Devices) where three dimensional polymer devices are fabricated by injection moulding and covered by a structured metal layer using electroless plating and laser ablation. The sensor concept based upon an extended electrode design which combines two different differential capacitors arrangements for a measurement range of ±180°. First MID-demonstrators were fabricated and characterized. The demonstrators show very promising properties. The sensors have a nice linear characteristic within ±45° and 45°-135° with a resolution of about 0,01° and a nonlineary better than 0.5% FSO. At different angular rates a dynamical hysteresis occurs. The dynamical hysteresis is proportional to the rotational speed of the sensor. The temperature dependence is very low and almost linear. No failure occured within first reliability tests of 100 sensors with thermal shock test and constant damp heat storage.

Zusammenfassung

Multifunctional 3D-packages can be fabricated with nearly any geometry using injection moulding. 3D line patterning can be performed on injection moulded parts with very flexible laser techniques. Finest line pitches can be realized with subtractive patterning as well as with additive laser direct structuring (LDS). For mounting of SMD and bare dies different assembly techniques can be used.

Zusammenfassung

Electrochemical machining with ultra short voltage pulses (ECF) is an innovative technique to machine electrochemically active materials particularly very hard materials at micrometer feature size. Since the ECF technique is an electrochemical process neither mechanical forces nor thermal load are applied to workpiece or tool. For that reason ECT it is an ideal technique for the production of microstructures. Especially the use of steel as the workpiece material makes the ECF technique a promising technique for the production of micro mould inserts, since steel is resistant against wear that occurs due to the injection process. Therefore the abilities and the limits of the ECF process for different types of tool steels are shown and the process parameters have been optimised. Acetic acid has been proven to be a suitable electrolyte for the ECF-process of tool steels. In this electrolyte tool steels like 1.2767 or 1.2312 can be processed with the ECF technique at a high quality. But in low-alloyed steels like 1.1730 only a poor quality can be obtained.

Zusammenfassung

MID-Bauteile lassen sich durch Kunststoffspritzguss mit fast beliebiger Geometrie herstellen. Die Laserstrukturierung ist ein sehr flexibel einsetzbares Ver-fahren um diese Bauteile mit einem 3D-Leiterbahnbild zu versehen. Zur Erzeugung feinster Strukturbreiten sind sowohl subtraktive Laserverfahren als auch das additive Verfahren der Laser-Direkt-Strukturierung möglich. Bei der vollsubtraktiven Laserstrukturierung wir das MID vollflächig mit Kupfer, Nickel und Gold beschichtet und anschließend wird durch UV-Laserstrahlung die Metall-schicht partiell entfernt und so von einander isolierte Bereiche erzeugt. Alternativ ist die selektive Laserablation einer dünnen vollflächigen Kupferstartschicht mit an-schließender Nachverstärkung des Restkupfers durch Nickel und Gold möglich. Beim additiven Verfahren der Laser-Direkt-Strukturierung wird Laserstrahlung zur Ak-tivierung der Oberfläche von MID-Bauteilen aus speziellen laseraktivierbaren Kunst-stoffen genutzt. Auf den aktivierten Bereichen scheidet sich in einem chemisch außenstromlosen Metallisierungsbad selektiv Metall ab. Die Laserstrahlung führt neben der Aktivierung zu einer Aufrauung der Oberfläche. Die Rauheit lässt sich über die Laserstrukturierungsparameter beeinflussen.

Zusammenfassung

Aufgrund der elektrischen und mechanischen Eigenschaften von metallbeschichteten Polymeren, wie sie aus der MID-Technik (Moulded Interconnect Device) bekannt sind, besteht die Möglichkeit, Wandlerfunktionen direkt durch MID-Bauteile zu realisieren. Dieser innovative Ansatz wird am Beispiel von Beschleunigungssensoren, Neigungssensoren, Neigungsschaltern sowie Drehwinkelsensoren demonstriert.

Zusammenfassung

The technology of Molded Interconnect Devices (MID) offers a very interesting alternative for many applications in MEMS and MOEMS suitable for multifunctional packages, because of its high potential in reducing the number of components and process steps as well as in miniaturization. In order to tap the full potential, the assembly of different kinds of electronic components like SMD and bare dies has to be feasible. In this paper the latest research results on the assembly of SMD and flipchips on laser patterned and electroless plated MIDs are presented. Both lead free soldering and bonding with electrically conductive adhesives was used for assembling SMD. Thereby the high peak temperature in the reflow process demands for a high temperature stability of the thermoplastic substrates. Flipchips were assembled using different kinds of adhesives on various substrates, including a special new type with molded polymer bumps in order to substitute the expensive process of stud bump bonding. The transition resistance of the contacts and the shear strength have been measured as an indicator for process quality and reliability after temperature shock and humidity storage stress. The thermal coefficient of expansion of the substrates used was found to have a major influence on the reliability. Reliable and suitable processes for various applications could be found.

Zusammenfassung

Electrochemical micromachining with ultrashort voltage pulses (ECF) is an innovative technique for milling of hard materials at micrometer feature size, especially stainless steel 1.4301. 3D-forming of the workpiece is achieved by moving the tool similar to conventional milling machines. Nevertheless ECF is an electrochemical process, i. e. tool and workpiece are submerged in an electrolyte and the surface is electrochemically etched by a galvanic current, therefore no mechanical forces are applied. Due to the use of ultrashort voltage pulses in the range between 10 ns and 100 ns the electrochemical process is confined to a small area round the tool. The corresponding gap between tool and workpiece can be varied with the pulse width around 10 μm. Presently the cutting speed is similar to the speed of electrical discharge machines (EDM), i. e. about 1 μm/s. The high spatial resolution combined with the possibility to machine hard materials makes ECF the ideal technique for processing micro moulds. For a higher throughput and a reasonable size of the moulds we use a hybrid technique combining conventional high precision milling, for the main structure, with ECF, for the finishing and the adding of microstructures. Since the two processes are carried out on different machines, special procedures and software tools are necessary to setup the workpiece in the ECF-machine and match the co-ordinate systems. On simple pattern we show the accuracy of ECF. Due to the absence of mechanical forces and the good definition of the working gap channels can be machined with practically no taper angles. Also complex mould pattern are presented, where micro moulds have been made in the hybrid technique. Among these are channels with a size of 3000 x 85 x 250 μm3 (LxWxD) and moulds for microfluidic devices.

Zusammenfassung

Die Handhabung kleinster Flüssigkeitsmengen wird in vielen Bereichen der modernen Technik immer wichtiger. Durch Freistrahldosierung nach dem Dispensing Well Plate-Verfahren (DWP) ist es möglich, die gewünschten kleinen Flüssigkeitsmengen mit hoher Genauigkeit zu dosieren. Grundsätzlich werden hierzu mikrofluidische Dosierchips mit entsprechenden Mikrokanal- und Mikrodüsenstrukturen eingesetzt, welche derzeit meist auf der Basis von Glas bzw. Silizium hergestellt werden. In dieser Arbeit wurde die Herstellbarkeit solcher mikrofluidischer Strukturen mittels kostengünstigen Kunststoff-Mikrospritzgusses untersucht. Die Düsen haben einen Durchmesser von 100 µm. Die Herstellung der Einsätze für die Spritzgießwerkzeuge erfolgte durch Hochpräzisionsfräsen. Mit diesen Einsätzen konnten Dosierchips aus verschiedenen Polymeren (COC, PEEK, PC) mit einer Zykluszeit von unter 25 Sekunden gefertigt werden. Aufgrund der geringen Fertigungstoleranzen von weniger als 10 µm konnte mit den Chips eine sehr gutes Dosierverhalten mit einer Reproduzierbarkeit des Dosierungsvolumens von weniger als 2 % erreicht werden.

Zusammenfassung

We report on an innovative low cost concept for the fabrication of micromechanical electrostatic actuators by microinjection moulding of 3D polymer devices followed by electroless plating and laser patterning of the metal layer 1. To demonstrate the new approach, we designed, fabricated and tested an electrostatic valve.

Zusammenfassung

We report on an innovative low cost concept for the fabrication of micromechanical sensors and actuators, where three dimensional polymer devices with high aspect ratios are fabricated by micro-injection molding and covered by metal using electroless plating. To demonstrate the new approach, we fabricated an accelerometer device consisting of two metallited polymer parts.

Zusammenfassung

Mit Kunststoffen lassen sich aufgrund der heute realisierbaren hohen Strukturauflösung bei ab- und umformenden Fertigungstechnologien wie dem Mikrospritzgießen oder Heißprägen mikrostrukturierte Bauelemente wirtschaftlich herstellen. Dies erfordert allerdings die Herstellung von Werkzeugen aus verschleißfesten Konstruktionswerkstoffen, die mit derzeit angewandten Fertigungsverfahren nur unter erheblichen Schwierigkeiten gefertigt werden können. Berliner Forscher um Rolf Schuster und Herhard Ertl 1 haben ein vielversprechendes, elektrochemisches Verfahren entwickelt, das zukünftig wesentlich zur Entspannung der Fertigungsprobleme beitragen kann. Im Rahmen einer Kooperation wurde auf der Grundlage dieses Verfahrens am Institut für Zeitmesstechnik, Fein- und Mikrotechnik der Hahn-Schickard-Gesellschaft (IZFM), zukünftig Hahn-Schickard-Institut für Mikroaufbautechnik (HSG-IMAT) der Demonstrator einer Anlage aufgebaut, mit deren Hilfe wichtige Erkenntnisse zum Aufbau industriell nutzbarer Anlagen gewonnen werden sollen.

Zusammenfassung

Die MID-Technik ermöglicht die Integration von elektrischen, fluidischen und elektromechanischen Systemfunktionen in einem mikrosystemtechnischen Bauteil. Ein Durchfluss-Sensorsystem zur präzisen Bestimmung von Volumenströmen von Fluiden wird vorgestellt. Das Sensorsystem wurde mit einem thermischen Strömungssensorchip in einem modularen 2K-MID Gehäuse realisiert. Volumenstrommessungen mit dem aufgebauten Durchfluss-Sensorsystem zeigen rausch-arme reproduzierbare Sensorsignale. Damit ist das MID-Gehäuse für Fluide insbesondere Gase bestens geeignet. Weiterhin sind Kunststoff-Metall-Verbundsysteme für die Herstellung von miniaturisierten elektromechanischen Elementen wie Biegebalken, Federn oder Elektroden geeignet, wie am Beispiel eines Beschleunigungssensors gezeigt wird. Die mechanischen und thermischen Eigenschaften des Kunststoff-Metall-Verbunds wurden analysiert. Die Ergebnisse zeigen, dass die MID basierten mechanischen Systeme sehr gut für kostengünstige Sensorsysteme geeignet sind. MID technologies enable to integrate electric, fluidic and electromechanical features within micromechanical systems. A flow sensor system for precise measurement of flow rate is presented. The thermal flow sensor chip was packaged by a modular housing made by two shot molding and subsequently selective electroless plating. Reproducible sensor signals with low noise were obtained from the flow sensor system mounted by MID technology. Therefore, the MID housing is well suited for fluids especially gases. Furthermore polymer-metal-composites are suited to fabricate miniaturized electromechanical elements like beams, springs and electrodes. This is demonstrated by an inertial transducer. The mechanical and thermal properties of the polymer-metal-composite were investigated. The results show, that MID technology is well suited to fabricate low cost sensor systems.

Zusammenfassung

We report on an innovative concept for the fabrication of micromechanical sensors and actuators, where polymer devices fabricated by conventional injection molding are covered by metal layers of copper, nickel-phosphorous and gold using electroless plating. In this paper we present first experimental results on the mechanical properties of miniaturized polymer mechanical beams covered with a metal layer. We find that at a sufficient metal layer thickness the mechanical properties of the beams are dominated by the metal cover surrounding the beam. Furthermore we discuss the design of a differential accelerometer to be fabricated using this novel technique.

Zusammenfassung

Design and modeling aspects of torsional 1D and 2D Micro Scanning Mirrors are presented. During the oscillation of the mirror plate the inertial moment gives rise to a deformation of the plate. This dynamic deformation results in a defocusing of the reflected laser beam. Therefore, the scan frequency of a device with a given size of the mirror plate and deflection angle is limited. Further restrictions arise from the demanded mechanical robustness like resistivity against shock and torsional stress. This leads to a minimum eignefrequency of the device which in the case of a rectangular shaped is proportional to the width of the spring. To enable a single mode operation it is advantageous that the torsion around the springs is the lowest mode sufficiently separated from all others. A FEM-analysis has been carried out to determine the mode sequence of a 1D and a 2D Micro Scanner respectively. The analytical calculated eigenfrequencies agree well with the numerical determined. Taken into account the result of the analytical and numerical investigations 1D and 2D Micro Scanning Mirrors have been designed and fabricated. The mirror and the springs are defined in a 20 to 30 micrometers thick single crystal silicon layer. The results of the experimental investigations with respect to the shock resistivity and the long run behavior probe the suitability of the modeling.

Zusammenfassung

A novel resonantly excited 2D-Micro-Scanning-Mirror is presented which makes use of an electrostatic driving principle allowing to locate the driving electrodes in the chip plane. The mechanical elements and the mirror plate consist of a 30 /spl mu/m thick single crystal silicon layer. The mirror plate is suspended by a gimbal mounting and can therefore be deflected along two axes. It is shown that a special isolation technique is suitable to separate the electrical potentials on the movable elements and therefore allows to excite the two oscillations independently. The isolation technique is based on the oxidation and polysilicon filling of 1 /spl mu/m wide trenches in the 30 /spl mu/m thick layer of silicon. The influence of the surrounding gas on the coupling of the oscillations is examined. No significant influence is observed. The performance of the novel 2D-Micro-Scanning-Mirror is demonstrated by the generation of various Lissajous patterns by the reflected laser beam. Frequency ratios of 1:1 up to 13:1 are obtained with the presented devices.

Zusammenfassung

Spatial light modulators (SLM) with addressing through a silicon backplane are gaining importance as microdisplays, for pattern generation in direct-writing systems and for several other applications. The use of CMOS technology has lead to small devices with a high grade of inspection. With the focus on direct-writing systems for photolithographic patterning we have developed tow micromechanical actuator technologies for SLMs with silicon backplane. Here we report on a third technology that employs an oil film on a mirror as micromechanical actuator. The principle of operation is explained and fabrication is described in detail. Demonstrators with 256 by 256 pixels have been fabricated with 16 micrometers and 20 micrometers pixel size. Photographs of programmed images are presented. Measurements of passive devices demonstrated a contrast ratio of 43:1 and a switching time of below 5ms.

Zusammenfassung

Das Zeitalter der Digitalisierung erfordert, dass Geräte, Maschinen und Anlagen ihre Umgebung wahrnehmen. Dies geschieht mit Hilfe von Sensoren, die unterschiedlichste Messgrößen, wie z.B. Temperatur oder Druck, erfassen und als Messwerte zur Weiterverarbeitung und Interpretation einem übergeordnetem System bereitstellen. Dabei sind die Sensorelemente und Sensoren zumeist in Technologien realisiert, die eine skalierbare Fertigung in großen Stückzahlen und damit geringen Einzelstückpreise erlauben. Es ist daher nicht verwunderlich, dass die Siliziumtechnologie den Sensormarkt dominiert. Damit verbunden sind jedoch auch sehr hohe Initialkosten, wenn es z.B. darum geht, kundenspezifische Anpassungen an ihnen vorzunehmen, sei es, um einen spezifischen Messbereich zu realisieren oder eine bestimmte Messgröße in einem vorgegebenen Bauraum zu erfassen. Hier bietet die Leiterplattentechnologie einen Ausweg, um Sensorelemente und Sensoren zu realisieren. Sie ist inzwischen jedermann, sogar dem Heimanwender, zugänglich, die Initialkosten sind gering, die Herstellungszeiten kurz und die Freiheitsgrade groß. Gleichzeitig stehen zahlreiche Substratmaterialien für verschiedene Anwendungsgebiete zur Verfügung, von FR4 für Standard-, über Polyimid für flexible, bis hin zu PTFE für Hochfrequenz- sowie Aluminium- und Kupferkernleiterplatten für temperaturkritische Anwendungen. Gleichermaßen bietet sie das Potential, sowohl für Kleinstserien als auch für die Fertigung in großen Stückzahlen eingesetzt werden zu können. Mit Hilfe von Ausleseelektroniken, die direkt auf die Leiterplatte bestückt werden, entstehen so kostengünstige Sensoren, die zudem hochperformant sein können. Nach einer Begriffsdefinition wird im Stand der Technik gezeigt, welche leiterplattenbasierten Sensorelemente und Sensoren schon heute existieren und welche Elektroniken verwendet werden können, um bspw. kapazitive, induktive und resistive Sensorelemente auszulesen. Dabei wird auch auf Schaltkreise eingegangen, die auf sogenannten Time-to-Digital-Konvertern (TDC) basieren, d.h. auf einer Zeitmessung beruhen. Diese haben den Vorteil, einerseits extrem stromsparend zu sein, andererseits auch extrem langzeitstabile Sensorsignale liefern zu können, da Zeitgeber inzwischen mit sehr guter Kurz- und Langzeitstabilität erhältlich sind. Auf einen speziellen Schaltkreis, den PCap01, wird dabei im besonderen eingegangen, da mit ihm sowohl kapazitive als auch resistive Sensoren realisierbar sind. Der grundlegende Umgang mit diesem Schaltkreis wird aufgezeigt und anhand von Untersuchungen zu Schirmkonzepten, zur Signalverarbeitung, zu Taktquellen sowie zur Leiterbahnführung dargelegt, wie, über die Herstellerangaben im Datenblatt hinaus, mit anwendungsspezifischer Firmware und digitaler Signalverarbeitung der entsprechenden Messwerte, performante Sensoren aufgebaut und langzeitstabile Sensorsignale erreicht werden können. Anhand von zwei Beispielen für kapazitive Sensoren, einem fluidischen, zweiachsigen Neigungssensor und einem fluidischen, einachsigen Neigungssensor sowie einem Beispiel für einen resistiven Sensor, einem thermischen Strömungssensor und einem Beispiel für einen induktiven Positionssensor wird belegt, wie im Zusammenspiel, aus leiterplattenbasiertem Sensorelement und Ausleseelektroniken auf Basis von Zeitmesstechnik, hochauflösende Sensoren entstehen. Dazu wird für die einzelnen Beispiele auf das Funktionsprinzip und die an diesem Sensor durchgeführten Untersuchungen sowie Optimierungen bzw. auf die grundlegende Auslegung und auf deren Firmware und Konfiguration eingegangen. Schließlich werden die mit den Sensoren erzielten Messergebnisse vorgestellt. An Stellen, an denen die Leiterplattentechnologie an ihre Grenzen stößt, werden für die Sensoren sogenannte AddOn-Prozesse vorgestellt, um diese Grenzen zu überwinden. Abschließend werden die bis dato erzielten Ergebnisse für die vier Sensoren einzeln diskutiert und eingeordnet. Es werden die aktuell noch existierenden Schwachstellen dargelegt und aufgezeigt, wie diese in aktuell laufenden bzw. in bereits bewilligten, künftig zu bearbeitenden Projekten überwunden werden können, mit dem Ziel, die Sensoren weiterzuentwickeln, um sie nach Abschluss der Arbeiten in die Serie überführen zu können. engl.: The age of digitalization requires that devices, machines and systems perceive their environment. This is done with the help of sensors that record a wide variety of measured variables, such as temperature or pressure, and provide them as measured values to a higher-level system for further processing and interpretation. The sensor elements and sensors are mostly realized in technologies that allow scalable production in large quantities and thus low unit prices. It is therefore not surprising that silicon technology dominates the sensor market. However, this is also associated with very high initial costs, for example when it comes to making customer-specific adaptations to them, be it to realize a specific measuring range or to record a specific measured variable in a given installation space. Here the printed circuit board technology offers a way out to realize sensor elements and sensors. It is now accessible to everyone, even the home user, initial costs are low, manufacturing times are short and the degrees of freedom are large. At the same time, numerous substrate materials are available for various applications, from FR4 for standard, to polyimide for flexible, to PTFE for high frequency, and aluminum and copper core PCBs for temperature critical applications. Similarly, it offers the potential for both low-volume and high-volume manufacturing. With the help of readout electronics, which are directly mounted on the printed circuit board, low-cost sensors are created, which can also be high-performance. After a definition of terms, the state of the art will show which PCB-based sensor elements and sensors already exist today and which electronics can be used to read capacitive, inductive and resistive sensor elements, for example. Integrated circuits based on socalled Time-to-Digital-Converters (TDC), i.e. based on time measurement, will also be discussed. On the one hand, these have the advantage of being extremely power-saving, and on the other hand, they can also provide extremely long-term stable sensor signals, since timers with very good short- and long-term stability are available. One special integrated circuit, the PCap01, will be discussed in particular, since it can be used to implement both capacitive and resistive sensors. The basic handling of this circuit is shown and, on the basis of investigations into shielding concepts, signal processing, clock sources and conductor routing, it is demonstrated how, beyond the manufacturer's specifications in the datasheet, with application-specific firmware and digital signal processing of the corresponding measured values, high-performance sensors can be constructed and long-term stable sensor signals can be achieved. Two examples of capacitive sensors, a fluidic, two-axis inclination sensor and a fluidic, single-axis inclination sensor, as well as an example of a resistive sensor, a thermal flow sensor and an example of an inductive position sensor, are used to demonstrate how highresolution sensors can be created from the interaction of a PCB-based sensor element and readout electronics based on time measurement technology. For this purpose, the functional principle and the investigations carried out on this sensor as well as optimizations or the basic design and their firmware and configuration are discussed for the individual examples. Finally, the measurement results obtained with the sensors are presented. At points where PCB technology reaches its limits, so-called AddOn processes are presented for the sensors in order to overcome these limits. Finally, the results obtained to date for the four sensors are discussed and classified individually. The weaknesses that currently still exist are presented and it is shown how these can be overcome in current projects or in projects that have already been approved and will be worked on in the future, with the aim of further improving the sensors so that they can be transferred to series production once the work has been completed.

Zusammenfassung

Flexible Elektronik gewinnt in der Industrie und Forschung zunehmend an Bedeutung. Ein wichtiger Bereich der flexiblen Elektronik ist das sogenannte System-in-Foil (SiF), bei dem Bauelemente und Strukturen auf oder in einer Polymerfolie integriert werden. Die Anwendungsbereiche von SiF umfassen Unterhaltungselektronik, Industrietechnik, Gesundheitswesen, Automobil-, Luft- und Raumfahrttechnik. Diese Arbeit beschäftigt sich mit der Montage und Biegecharakterisierung von SMDs und ultradünnen Chips auf Foliensubstraten. Dafür wurde ein dynamischer Biegeprüfstand zur Charakterisierung von Folienaufbauten konzipiert und umgesetzt. Anschließend wurden mithilfe einer Versuchsplanung leitfähiges Kleben und Löten zur Integration von SMDs auf Foliensubstraten vergleichend untersucht, wobei Prozess- und Materialvariationen angewendet wurden. Die erstellten Aufbauten wurden mithilfe von Scher- und Biegeprüfungen bewertet. Es wurde festgestellt, dass SMDs, die durch Löten auf Foliensubstrate aufgebracht wurden, im Vergleich zu geklebten SMDs höhere Scherkräfte aufweisen. Im Gegensatz dazu zeigten die geklebten SMDs eine höhere Anzahl an Biegezyklen bis zum Ausfall. Das Oberflächenfinish erwies sich als ein sehr wichtiger Einflussfaktor auf das Biegeverhalten der Aufbauten. Außerdem wurde ein Konzept zur Integration von ultradünnen Chips auf Foliensubstraten mithilfe von adaptiver Belichtung und Dispenstechniken erarbeitet, das erfolgreich durchgeführt und unter dynamischer Biegeprüfung evaluiert wurde. Die entwickelte Prozesskette ermöglicht es, Chips unabhängig von ihrer Bestückungsgenauigkeit zuverlässig zu erkennen und zu kontaktieren. Mit diesem Konzept wurde ein Aufbau von weniger als 130 μm Dicke ohne große Versteifung an der Verbindungsstelle realisiert. Bei der Biegeprüfung unter 10 mm Biegeradius haben die Aufbauten Tests mit über 10.000 Biegezyklen bestanden. Diese Prozesskette bildet die Grundlage für die Herstellung von multichipfähigen Mikrosystemen.

Zusammenfassung

In der vorliegenden Arbeit wird eine Prozesskette vorgestellt, die es ermöglicht, additiv gefertigte 3D-Körper zu einem mechatronischen Bauteil zu veredeln, indem unmittelbar auf der Oberfläche elektrisch leitfähige Strukturen erzeugt werden. Die Prozesskette basiert auf der Maskierung der Bauteiloberfläche und dem selektiven Abtrag der Maskierung entsprechend der Schaltungsgeometrie mittels Laserstrahlung, bei dem auch die Bauteiloberfläche bearbeitet wird. In einem nasschemischen Badprozess werden dann nacheinander die Oberfläche mit Palladiumkeimen beaufschlagt, die Maskierung final entfernt und Metallschichten (Cu/Ni/Au) außenstromlos abgeschieden. Der Prozess ist somit nicht auf Spezialwerkstoffe angewiesen, sondern ermöglicht den Einsatz branchenbekannter Materialien aus dem Bereich der additiven Fertigung, sofern diese nicht elektrisch leitfähig sind. Als Maskierungsmaterial wurden eine anorganische Schicht in Form eines Natriumsilikatglases und eine organische Schicht in Form eines photostrukturierbaren Negativlacks untersucht. Das anorganische Maskierungsmaterial musste aufgrund starker Rissbildung auf 3D-Bauteilen jedoch zunächst verworfen werden. Das Verfahren wurde unter Verwendung des Digital Light Processing als Modellprozess der additiven Fertigung erarbeitet und die erzeugten Metallschichten hinsichtlich Haftfestigkeit (Hot-Bump-Pull-Tests), Leitfähigkeit (Vierleitermessung) und Oberflächenrauheit (Weißlichtinterferometrie) charakterisiert. Dabei konnten Haftfestigkeiten und Leitfähigkeiten der Metallschicht vergleichbar mit industriell gängigen, spritzgegossenen laser direktstrukturierten Mechatronic Interconnect Devices aufgezeigt werden. Zum Nachweis der Transferierbarkeit des Verfahrens auf andere additive Fertigungsverfahren wurden Bauteile mit vier weiteren Verfahren, Stereolithographie, PolyJet, selektives Lasersintern und HP Multi Jet Fusion, prozessiert und die Metallstrukturen charakterisiert. In allen Fällen konnte, trotz der stark unterschiedlichen Oberflächeneigenschaften, eine gute Selektivität der Metallabscheidung gezeigt werden. Abschließend wurden Designregeln für das Verfahren aufgestellt.

Zusammenfassung

Diese Arbeit befasst sich mit Methoden und Prozessen der Produktentwicklung für die Mikrosystemtechnik. Hierbei fließt der Kontext der Individualisierung in die Methoden und Prozesse ein. Das Ziel dieser Arbeit ist es, konkrete Maßnahmen für eine effizientere Herstellung von individualisierten Mikrosystemen (iMST) systematisch abzuleiten. Zur Erreichung des Ziels werden in dieser Arbeit generelle Anforderungen aus diversen Anwendungsbereichen aufgezeigt. Anschließend wird mittels einer Fallstudien ein iMST hergestellt und strukturiert beobachtet. Mit dieser Studie zeigt die Arbeit konkrete Schwachstellen und mögliche Handlungsansätze in der Entwicklung von iMST auf. Um über diese Studie hinaus weitere Erkenntnisse von Schwachstellen und erforderlichen Maßnahmen zu erlangen, werden mehrere Unternehmen im Rahmen einer qualitativen Analyse befragt. Mit dieser Datengrundlage bildet die Arbeit eine Methodik, welche Prozesse, Methoden, Anforderungen und Werkzeuge vereint. Die Methodik zeigt, in welchen Fällen und Phasen die entsprechenden Methoden eingesetzt werden sollen. Aufgrund der Herausforderungen von individualisierten Anwendungen stellt diese Arbeit die wichtigsten Methoden zur Bewerkstelligung dieser Herausforderungen bereit. Ein wissensbasiertes Werkzeug (KETTS) und die Nutzung von M/ECAD-Applikationen bieten großes Potenzial zur Effizienzsteigerung des Entstehungsprozesses. Diese werden in dieser Arbeit genauer beleuchtet, entwickelt und getestet. Die Methodik wird mit der Herstellung eines weiteren iMST validiert, wodurch der Mehrwert der ausgewählten Prozesse und Methoden deutlich wird. Im abschließenden Teil dieser Arbeit werden die Beschränkungen sowie potenzielle Forschungsrichtungen in der Produktentwicklung und Mikrosystemtechnik erörtert. Hierbei werden insbesondere die Möglichkeiten zur Weiterentwicklung und Erweiterung der einzelnen Methoden betrachtet. This thesis deals with methods and processes of product development for microsystems. Thereby, the context of individualization enters into the methods and processes. The goal of this study is to systematically derive specific measures for more efficient development and production of individualized microsystems (iMST). To achieve this goal, general requirements from various application areas are identified in this thesis. Then, through a case study, an iMST is manufactured and observed systematically. With this study, the thesis shows specific weaknesses and possible approaches in the development of iMST. In order to gain further insights of weaknesses and necessary measures beyond this study, several companies are interviewed in a qualitative study. With this database, the work creates a methodology that combines processes, methods, requirements and tools. The methodology shows in which cases and stages the respective methods should be used. Due to the challenges of individualized applications, this work provides the most important methods to overcome these challenges. A knowledge-based tool (KETTS) and the use of M/ECAD applications offer great potential to increase the efficiency of the creation process. These will be explored, developed and tested in more detail in this thesis. The methodology is validated with the manufacturing of another iMST, which demonstrates the added value of the selected processes and methods. The final part of this thesis discusses the limitations as well as potential research directions in product development and microsystems engineering. In particular, the possibilities for further development and expansion of the individual methods are considered.

Zusammenfassung

Die weitere Miniaturisierung von Beschleunigungssensoren stößt unter Verwendung herkömmlicher Wandlerprinzipien aufgrund der Skalierungsgesetze bei einer isometrischen Verkleinerung der Sensorstrukturen an ihre Grenzen. In dieser Arbeit wird die Miniaturisierung von Beschleunigungssensoren daher durch den Einsatz einer hochsensitiven quantenmechanischen Tunnelstrecke untersucht. Die theoretische Auslegung der Sensorstrukturen bedarf einer eingehenden Analyse der Zusammenhänge zwischen dem Tunneleffekt, der geometrischen Form und Größe der FederMasse-Systeme (FMS) sowie der Parameter der elektrostatischen Aktorik. Die Ergebnisse zeigen zwei Modelle mit einfachem (M1) und spiralförmigem (M2) Federbalken sowie zusätzlicher seismischer Masse und elektrostatischer Aktorik. Durch die geringere Steifigkeit kann mit M2 bei gleichbleibender Empfindlichkeit eine weitere Miniaturisierung erfolgen. Die Tunnelstrecke wird an der Position der größten Empfindlichkeit integriert. Die Steifigkeit der Strukturen ist durch die anziehenden Kräfte zwischen den Tunnelelektroden bei Abständen weniger nm begrenzt. Der Flächenbedarf der Sensorkernfläche (M1 & M2) beträgt einige 10x10 µm². Die Implementierung der Tunnelelektroden erfolgt, nach Herstellung der Sensorstrukturen durch den Foundry Service PolyMUMPs von MEMSCAP Inc., durch den Einsatz eines „Focused Ion Beam“ (FIB, Ga+) und die Abscheidung von metallorganischem Precursormaterial (MeCpPtMe3) mit einem „Gas Injection System“. Dies führt insbesondere zu zwei Herausforderungen: Zum einen muss ein Prozess entwickelt werden, um Elektrodenspitzen weniger nm im Radius zu generieren. Zum anderen bedarf es einer Untersuchung des metallorganischen Gefüges sowie geeigneter Parameter des FIB, um die Tauglichkeit der Elektroden für den Tunneleffekt sicherzustellen. Daher werden Materialanalysen des Gefüges (Transmissionselektronenmikrokopie und energiedispersive Röntgenspektroskopie) sowie der elektronischen Parameter (Widerstandsmessung und Tunnelmikroskopie) durchgeführt. Die Ergebnisse zeigen, dass die Tunnelelektroden mit hohen Blendenströmen des FIB (260 pA, 30 kV) hergestellt werden müssen. Dies führt zu einem erhöhten Platinanteil sowie einer homogenen Verteilung der Platinpartikel im Gefüge. Es werden Elektrodenspitzen mit Radien bis 5 nm hergestellt und initiale Elektrodenabstände von etwa 30 nm bis 300 nm erreicht. Die messtechnische Charakterisierung zeigt den Nachweis des Tunneleffekts bei Tunnelspannungen von 200 mV bis 1 V durch die exponentielle Abhängigkeit zwischen Tunnelstrom und Elektrodenabstand. Die Anregung der Sensorstrukturen mit einer äquivalenten Beschleunigung erfolgt durch die elektrostatische Aktorik. Durch die steigende Sensitivität des Tunneleffekts nimmt das Signalrauschen mit Verkürzung des Tunnelabstandes zu. Der Messbereich beträgt 20 g bei einer Empfindlichkeit des Messsignals von bis zu einigen 10 pA/g. Unter Verwendung der metallorganischen Elektroden lassen sich, je nach Tunnelspannung, Ströme bis 150 pA messen. Die Begrenzung des Tunnelstroms ist auf den hohen Materialwiderstand der Elektroden zurückzuführen. Aus den Ergebnissen folgt die Anforderung nach metallisch „reinen“ Tunnelelektroden, da der dem Tunnelstrom äquivalente Messbereich (einige 10 nA) durch die metallorganischen Materialien maßgeblich begrenzt wird. Im Bezug auf frühere Arbeiten zeigen die Ergebnisse dieser Arbeit, dass der hochempfindliche Tunneleffekt, anstatt zur Erhöhung der Sensorauflösung eines Beschleunigungssensors, auch zur deutlichen Miniaturisierung der Sensorfläche genutzt werden kann. The further miniaturization of accelerometers using conventional transducer principles reaches its limits due to the scaling laws at an isometrical reduction of the sensor structure’s size. In this work, the miniaturization potential of acceleration sensors using a highly sensitive tunneling section is investigated. The theoretical design of the sensor structures requires an in-depth analysis of the relationships between the tunneling effect, the geometric shape and the size of the spring-mass systems, as well as the parameters of the electrostatic actuator. The results show two models with a single (M1) and a spiral (M2) spring beam as well as the additional seismic mass and the electrostatic actuator. Due to the lower stiffness, further miniaturization can be achieved with M2 while maintaining the same sensitivity. The tunneling section is integrated at the position of the greatest sensitivity. The stiffness of the structures is limited by the attractive forces between the tunneling electrodes at distances of a few nm. The area requirement of the sensor core area (M1 & M2) amounts several 10x10 µm². After fabrication of the sensor structures by MEMSCAP Inc.’s foundry service PolyMUMPs, the tunneling electrodes are implemented using a “Focused Ion Beam“ (FIB, Ga+) and deposition of metal-organic precursor material (MeCpPtMe3) with a gas injection system. This presented significant challenges: First, a stable and reproducible process has to be developed to create electrode tips with radii of some nm. Second, an analysis of the metal-organic microstructure and suitable parameters of the FIB are required to ensure the suitability of the electrodes for the tunneling effect. Therefore, material analyses of the microstructure (transmission electron microscopy and energy dispersive X-ray spectroscopy) and electronic parameters (resistivity measurement and tunneling microscopy) are performed. The results show that high aperture currents (260 pA, 30 kV) are necessary to achieve an increased platinum content as well as a homogeneous distribution of the platinum particles in the microstructure. Electrode tips with radii down to 5 nm can be fabricated, and initial electrode spacing of about 30 nm to 300 nm are achieved. The tunneling effect can be demonstrated from tunneling voltages from 200 mV up to 1 V by the exponential dependence between the tunneling current and the electrode spacing. The excitation of the sensor structures with an equivalent acceleration is performed by the electrostatic actuator. Due to the increasing sensitivity of the tunneling effect, the signal noise increases with the shortening of the tunneling distance. The measuring range amounts 20 g with a sensitivity of the measuring signal of up to some 10 pA/g. Using the metal-organic electrodes, currents up to 150 pA can be measured reliably, depending on the tunneling voltage.The limitation is due to the high material resistance of the electrodes. The research results show the essential requirement for purer metallic materials since the measuring range equivalent to the tunneling current (some 10 nA) is significantly limited by the metal-organic materials. Regarding previous work, the results of this work show that the highly sensitive tunneling effect can also be used to significantly miniaturize the sensor area, instead of being used to increase the sensor resolution of an accelerometer.

Zusammenfassung

The aim of this work is to investigate the reliability of microelectronic assemblies encapsulated by thermoset injection molding. One part of this work was to build up an improved understanding of the process simulation. Research was conducted in order to build up a knowledge base of the material parameters required for injection molding simulations of thermosets as well as their underlying measurement methods. In addition, the effect of simulation parameters on the error of predicting filling behavior was studied. The goal was to develop an understanding of which simulation parameters are particularly relevant and which model simplifications can be made since this is directly related to the measurement effort of material data and computing time. A further question is which minimum wall thickness (< 500 μm) can be achieved during encapsulation, which modes of stress are generated in the assembly, and how exactly this can be represented by the simulation. Established simulation software providers have no information about the minimum achievable wall thickness. The manufactured test assemblies were further used for reliability tests, whereby the service life of the assemblies was determined by means of an online resistance measurement. From the tests, the failure causes of encapsulated microsystem assemblies can be identified. Parallel to the reliability tests, numerical simulations mirroring the thermo-mechanical effects subjected to boundary conditions taken from the temperature cycling tests were carried out. Lifetime models were derived from the experimental results and the simulations. The derived lifetime models were further put through validation by means of a different package layout with the help of numerical simulations and experimental tests. Finally, design rules for reliable microsystem assemblies with regard to sprue planning, component alignment, component type, etc. were deduced from the investigations based on simulation and life cycle models.

Zusammenfassung

Elektronische Produkte sind fester Bestandteil unseres täglichen Lebens. Fortschreitende Miniaturisierung, komplexere Funktionen und verkürzte Produktlebenszyklen stellen die Hersteller vor große Herausforderungen. Der Einsatz von 3D-Drucktechnologien, ergänzt durch die Platzierung von Komponenten und die Integration elektrischer Verbindungen, ermöglicht die Herstellung elektronischer Systeme mit hoher Flexibilität und eingebetteten Schaltkreisen. Mit der steigenden Komplexität wachsen jedoch die Anforderungen an Prozesse und Materialien. Bewährte Klebstoffsysteme aus der Aufbau- und Verbindungstechnik haben das Potenzial, diese Anforderungen zu erfüllen. In dieser Arbeit wird ein neuartiger Ansatz für die Verarbeitung von Klebstoffen mit einem extrusionsbasierten UV-unterstützten 3D-Dosierverfahren vorgestellt. Ziel der Arbeit ist der Nachweis, dass das schichtweise Dispensen von leitfähigen und nicht leitfähigen Reaktionsklebstoffen in Kombination mit der Integration elektronischer Komponenten geeignet ist, um 3D-Schaltungsträger mit zuverlässiger elektrischer Funktion und zugleich mit mechanisch und thermisch stabiler Gehäusefunktion zu fertigen. Die erzielten Ergebnisse zeigen, dass dualhärtende Klebstoffe, insbesondere Epoxidsysteme, eine vielversprechende Wahl für die additive Fertigung sind. Mit der vorgeschlagenen Methode und den Prozessvarianten können elektronisch funktionale Bauteile additiv gefertigt werden, sofern eine sorgfältige Materialauswahl durchgeführt wird. Die Erkenntnisse dieser Arbeit liefern Designregeln und bieten eine Grundlage für die Umsetzung eingebetteter Schaltungen und industrieller Anwendungen.

Zusammenfassung

Bereits seit einigen Jahren befindet sich das Feld der flexiblen Elektronik im Wachstum. Diese zeichnet sich insbesondere durch ihre hohe mechanische Flexibilität, aber auch durch eine niedrige Bauhöhe und geringe Masse aus. Die Einbettung ultradünner, mechanisch flexibler Siliziumchips in Kunststofffolien erweitert die flexible Elektronik und eröffnet das Potential, Sensorsignale direkt am Ort der Erfassung auswerten zu können. Um eine zielführende Prototypenfertigung dieser Foliensysteme mit eingebetteten, ultradünnen Siliziumchips zu ermöglichen, wurde in dieser Arbeit eine digitale Prozesskette entwickelt, mit der die Fertigung dieser Systeme individualisiert werden kann. Dazu wurden geeignete Einzelprozesse entwickelt und deren Prozessparameter betrachtet. Zu Beginn wurden Prozesse zur Montage der ultradünnen Siliziumchips untersucht, um diese sowohl manuell als auch automatisiert klebtechnisch fixieren zu können. Es wurden dabei sowohl die Montage einzelner Chips als auch die simultane Klebung mehrerer ultradünner Chips berücksichtigt, indem eine innovative Fügemethode unter Zuhilfenahme einer temporär haftenden Klebefolie entwickelt wurde. Damit konnte eine homogene Klebung von 4,7 mm x 4,7 mm großen ultradünnen Siliziumchips mit maximaler Klebstoffschichtdicke von 15 µm erreicht werden. Anschließend wurde ein Conformal-Coating-Sprühverfahren zur Applikation eines mechanisch flexiblen, photosensitiven Lötstoppmaterials untersucht, in das die fixierten Siliziumchips eingebettet wurden. Die Verwendung photolithographischer Prozesse erlaubte die Freistellung von Kontaktflächen auf den geklebten Siliziumchips. Dazu wurde ein auf UV-LEDs basierendes Direktbelichtungsverfahren eingesetzt, sodass auf zusätzliche Photolithographiemasken verzichtet werden konnte. Es wurde weiterhin eine Methodik entwickelt, mit der die Platziertoleranz und die Verdrehung von gefügten, ultradünnen Siliziumchips optisch erfasst und durch ein individuell erstelltes Direktbelichtungslayout kompensiert werden konnte. Mittels Inkjetdruck nanopartikulärer Tinten wurden die eingebetteten Siliziumchips mit Widerstandswerten im niedrigen zweistelligen Ohm-Bereich elektrisch kontaktiert. Die Analyse unterschiedlicher Kontaktöffnungsausprägungen ergab, dass beim verwendeten Lötstoppmaterial eine runde Kontaktöffnungsgeometrie mit 90 µm Durchmesser vorteilhaft für die Kontaktierung der Chipmetallflächen über Inkjetdruck ist. Die entwickelten Einzelprozesse wurden anschließend in eine anwendungsorientierte, digitale Prozesskette überführt. Hierbei hatte die Reihenfolge der Einzelprozesse einen entscheidenden Einfluss auf die Durchführbarkeit der Prozesskette und die erzielten Resultate der jeweiligen Einzelprozesse. So konnte festgestellt werden, dass zu Beginn der digitalen Prozesskette die Montage der ultradünnen Siliziumchips, gefolgt von der Einbettung mittels Conformal-Coating, photolithographische Freistellung der Chipkontaktflächen mittels Direktbelichtung und Entwicklung sowie der sich anschließenden elektrischen Kontaktierung über Inkjetdruck erfolgen sollte. Die Bestückung mit diskreten Bauelementen sollte abschließend erfolgen, um die übrigen Prozessschritte nicht einzuschränken. Die resultierenden Foliensysteme mit eingebetteten, ultradünnen Siliziumchips zeigen nach Ablösen vom starren Träger eine hohe mechanische Flexibilität und können so auf gebogenen Oberflächen eingesetzt werden.

Zusammenfassung

Bei der Neigungswinkelmessung wird die relative Lage von Objekten zum Erdschwerfeld bestimmt. Stand der Technik im Bereich der Konsumgüter, der Industrietechnik, der Messtechnik oder der Fahrzeugtechnik sind vor allem Sensoren auf Basis von Beschleunigungssensoren. Diese werden hauptsächlich als Mikrosysteme (MEMS) ausgeführt und mittels mikrotechnischer Verfahren hergestellt. Die Neigungswinkelmessung, erfolgt dabei anhand einer Messung der Projektion der Erdbeschleunigung auf die sensitive Achse oder Achsen. Der in dieser Arbeit vorgestellte flüssigkeitsbasierte, kapazitive Sensor soll eine Alternative zu den MEMS-Beschleunigungssensoren bieten. Aufgrund seiner einfachen Herstellbarkeit mittels Standard-Surface-Mount-Technology (SMT) kann er durch kleine und mittelständische Unternehmen (KMU) auf meist vorhandener Anlagentechnik produziert werden. Die MEMS-Fertigung hat den Vorteil der kostengünstigen Massenfertigung im Batch. Dafür sind jedoch technologisch anspruchsvolle Reinraumprozesse notwendig, die nur bei großen und darauf spezialisierten Unternehmen zu finden sind. Die Arbeit stellt zuerst den Stand der Technik der Neigungs- und Beschleunigungsmessung sowie der Molded Interconnect Device (MID) Technologie vor und beschriebt dann das Sensorprinzip der flüssigkeitsbasierten +/-90° und 360° Neigungswinkelmessung. Dieses basiert darauf, dass sich die Oberfläche einer Flüssigkeit aufgrund der Gravitationskraft immer horizontal ausrichtet. Der Sensor verwendet eine dielektrische Flüssigkeit in einer teilweise gefüllten Kavität und bestimmt kapazitiv seine Lage zur Flüssigkeitsoberfläche. Zur Sensorauslegung werden ein analytisches Modell sowie eine Monte-Carlo-Simulation verwendet. Danach werden die Aufbau- und Verbindungstechniken (AVT) zur Herstellung der Sensoren beschrieben. Es kommen dabei zwei Varianten für die Ausformung der Kavität für das Fluid zum Einsatz. Eine Sensorvariante nutzt die die MID-Technik. Eine andere Möglichkeit ist die Verwendung von Standard-Leiterplatten, welche gestapelt und verlötet werden. Anschließend wurden die grundlegenden Sensoreigenschaften von drei Sensorvarianten charakterisiert. Dazu wurden Kennlinien der Sensoren bei Raumtemperatur aufgenommen und daraus eine Kalibrationsvorschrift für die Winkelberechnung abgeleitet. Da Neigungswinkelsensoren eine Sensitivität auf Neigungen quer zur Messachse haben können, wurden Messungen mit unterschiedlichen Querneigungen durchgeführt. Zur Charakterisierung der dynamischen Eigenschaften wurde die Abklingzeit der Sensoren bestimmt. Da der Sensor einen systematischen Einfluss der Temperatur auf die Steigung der Sensorkennlinie zeigt, wurde dieser gemessen und Möglichkeiten zur Kompensation untersucht. Temperaturschocktests zur beschleunigten Alterung schließen die Charakterisierungen der Sensoren ab. Abschließend diskutiert die Arbeit die Monte-Carlo-Simulation, die Temperaturkompensation und die Ergebnisse des Benchmarks. Ein Vergleich einer Monte-Carlo-Simulation mit einem analytisch berechenbaren Fall zeigt die grundsätzliche Eignung der Simulation zur Beschreibung des Sensorverhaltens. Die Ergebnisse der Simulation für verschiedene Temperaturen wurden drüber hinaus mit Messungen von Sensoren und einem rechnerischen Ansatz zur Temperaturkompensation verglichen. Dabei zeigte sich ebenfalls eine sehr gute Übereinstimmung von Simulation und Messung. Mithilfe der mathematischen Temperaturkompensation konnte der systematische Temperaturfehler weitgehend korrigiert werden. Bei der Diskussion des Benchmarks werden die wichtigsten technischen Eigenschaften der Sensoren, Allan-Deviation, Temperaturstabilität und Nichtwiederholbarkeit verglichen. Dabei zeigten die flüssigkeitsbasierten Sensoren eine im Zielmarkt wettbewerbsfähige Performance, vor allem für Anwendungen, welche ein geringes Rauschen, eine gute Bias-Stabilität sowie eine geringe Hysterese des Sensorsignales benötigen.

Zusammenfassung

Highly integrated electronic devices are required to enable the trend of personalization, automation, connection and electrification in the automotive industry. The increasing demands for higher performance, lower cost and smaller size of the automotive packages have brought the reliability issues to the forefront. This work aims to investigate the reliability of electronic components subjected to high current loads via experimental and numerical analysis. The study is focusing on the failure analysis of interconnection technology, since it has become one of the weakest links in the assembly with the trend of miniaturization. Power cycling tests with various loading conditions have been performed on the assemblies of shunt components. The resistance is electrically monitored during the test and failure is reported when 50% resistance increment is detected. Lifetime data are collected and further evaluated statistically with 3-parameter Weibull distribution. The self-heating behavior of the components is studied with thermography measurements. The failure mechanism of the SnAgCu (SAC) solder joints under active power cycling load is investigated via light microscopy, scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), computer tomography (CT) and electron backscatter diffraction (EBSD) techniques. The microstructural evolution of the solder material under current stressing is analyzed via the mentioned material characterization techniques. Failure mechanisms such as thermo-mechanical fatigue (TMF) and electromigration (EM) are discussed in details based on the experimental findings. To assess the response of the assembly subjected to current stressing, finite element method (FEM) simulations are performed to evaluate the multiphysics thermal-electrical-mechanical fields in the package. The accumulated plastic strain and divergence of material flux density are calculated. The simulative damage parameters are utilized to characterize the failure modes observed from the tests. A lifetime model is derived on the basis of lifetime data obtained from tests and numerical results. This provides a physics-of-failure based understanding of the performance of solder interconnects under field-like active loads and serves to assess the reliability of the package design under use condition.

Zusammenfassung

Durch aktuelle Trends wie das Internet der Dinge (IoT), System-on-foil oder Wearables erfährt die digitale Drucktechnik seit Jahren ein großes Wachstum, das sich aller Voraussicht nach auch in den nächsten Jahren fortsetzt. Dabei bietet die Drucktechnik die Möglichkeit einer kostengünstigen Herstellung von elektronischen Systemen. Nanopartikuläre Silbertinten werden aufgrund ihrer elektrischen und chemischen Eigenschaften für die Elektronikherstellung eingesetzt. Nanopartikuläre Goldtinten sind nicht soweit verbreitet, und aufgrund der relativ hohen Kosten ist deren kommerzielle Verfügbarkeit deutlich eingeschränkter als für Silbertinten. Durch die Eigenschaften von Gold könnten sich beispielsweise im Bereich der Medizintechnik oder Healthcare neue Einsatzmöglichkeiten ergeben. Das Ziel dieser Arbeit ist es, neue Erkenntnisse über inkjet-druckbare nanopartikuläre Gold- und Silbertinten hinsichtlich ihrer Langzeitstabilität und Biokompatibilität zu erlangen, anhand derer sich neue Anwendungen ergeben können. In Voruntersuchungen wurde für jede Tinten-Substrat-Kombination ein geeigneter Druck- und Sinterprozess erarbeitet. Anschließend wurden mäanderförmige Teststrukturen mit den optimierten Parametern hergestellt und untersucht. Der Schwerpunkt liegt vor allem im Bereich der Langzeitstabilität und der Biokompatibilität. Hierfür sollen beschleunigte Alterungsversuche im Klimaschrank neue Erkenntnisse zum Langzeitverhalten der gedruckten Goldstrukturen liefern. Zytotoxizitätstests sollen den Einfluss der gedruckten Goldstrukturen auf lebende Zellen in Abhängigkeit von den Herstellungsparametern zeigen und so eine Beurteilung für den Einsatz in medizintechnischen Anwendungen erlauben. Als Referenz dienen nanopartikuläre Silbertinten, die kostengünstiger und auf dem Markt deutlich verbreiteter sind.

Zusammenfassung

The functionality of silicon-based photonic optical phased arrays (OPAs) depends strongly on temperature. Therefore, their thermal management requires not only efficient heat dissipation but also reduction of on-chip temperature gradients and precise temperature stabilization. The thermal stability requirements needed to guarantee the correct functionality of OPA systems, depend on the system's implementation and its performance specifications. To allow for a system-independent statement of the thermal stability requirements, a precise understanding of the influence of different thermal loads, such as temperature gradients, temperature fluctuations, and temperature offsets, on the functionallity of the OPA system is required. In this work, first investigations of the influence of these thermal loads on the response of OPAs are presented. Based on the results of these investigations, a general set of thermal stability requirements is derived, and different solutions for thermal management of OPA systems are proposed and evaluated. It is demonstrated that applying the proposed solutions reduces the influence of thermal loads on the functionality of the OPA system, guaranteeing its proper operation. Finally, a method for active compensation of thermally induced distortions in the OPAsystems is also proposed and demonstrated using a prototype system.

Zusammenfassung

Diese Arbeit befasst sich mit einem neuen Verfahren zur fälschungssicheren und markierungsfreien Rückverfolgung von Bauteilen in der Produktion. Als Identifikationsmerkmal dienen individuelle Strukturen auf der Bauteiloberfläche, die aufgrund von statistischen Prozessen in deren Herstellung entstehen. Im Vergleich zu konventionellen Verfahren der Einzelteilverfolgung (Beschriftung, RFID) werden die Bauteile gegenüber ihrem Originalzustand nicht verändert. Die Oberflächenstrukturen der Bauteile werden in einem Foto aufgenommen, wofür in dieser Arbeit ausschließlich handelsübliche Hardwarekomponenten zum Einsatz kommen. Eines der verwendeten Hardwaresysteme wurde speziell für diese Arbeit aufgebaut, das andere ist ein kommerziell erhältliches Videomesssystem zur automatischen optischen Inspektion. Mithilfe eines speziellen Algorithmus werden die Oberflächeninformationen im Bild in einen Hashwert konvertiert, der nur einen Bruchteil der Datengröße des ursprünglichen Bildes besitzt. Bei einem Identifikationsprozess wird dann die Ähnlichkeit der Hashwerte verglichen, indem die Hamming-Distanzen berechnet werden. Somit wird der Identifikationsprozess durch die Konvertierung der Oberflächenaufnahmen in Hashwerte erheblich beschleunigt und die erforderliche Speicherkapazität zur Registrierung aller Bauteile reduziert. Der im Rahmen dieser Arbeit entwickelte Algorithmus basiert auf der Diskreten Kosinustransformation. Dadurch werden bei der Erstellung eines Hashwerts nur bestimmte Frequenzanteile eines Bildes berücksichtigt. Der Einfluss und die Wahl der berücksichtigten Frequenzanteile wird anhand mehrerer Messreihen umfangreich diskutiert. Im experimentellen Teil der Arbeit wird zunächst die Einzigartigkeit der Oberflächenstrukturen verschiedener Kunststoffmaterialien untersucht und die Eignung des aufgebauten Systems grundlegend demonstriert. Demnach stellen die Oberflächenstrukturen einiger Materialien eine Physical Unclonable Function dar. Weiter werden aus den Messergebnissen ein tiefgehendes Verständnis für die Häufigkeitsverteilung der Hamming-Distanzen aufgebaut und zwei Ansätze dargelegt, um die Identifikationssicherheit mit geringem Aufwand abschätzen zu können. Im Hinblick auf die Einzelteilverfolgung in der Produktion werden im nächsten Schritt Einflüsse untersucht, welche sich auf die Oberflächenstrukturen im Bild direkt auswirken können. Demnach ist die präzise Reproduzierbarkeit der Objektpositionierung im Bild eine wichtige Voraussetzung, um die zuverlässige Identifizierung aller Objekte zu gewährleisten. Am Beispiel von Kunststoffplättchen wird gezeigt, wie die softwareseitige Positionskorrektur dazu beitragen kann. In weiteren Versuchen werden durch Kratzer und Temperaturschocktests reale Veränderungen der Oberfläche herbeigeführt. Es zeigt sich, dass die Identifikationssi- cherheit zwar verringert wird, die Identifizierung trotz dessen jedoch möglich sein kann. Die Beleuchtungsstärke und das Umgebungslicht beeinflussen die Identiflzierung nur sekundär. Auf Basis der gewonnenen Erkenntnisse wird das Verfahren in zwei Produktionslinien getestet. Einerseits werden Leiterplatten in der SMD-Bestückung rückverfolgt. Als Identifikationsmerkmal dienen in diesem Fall die Oberflächenstrukturen einer Passermarke aus Kupfer. Andererseits werden die Kunststoffgrundkörper von MIDs (Molded Interconnect Devices) innerhalb der MID-Prozesskette rückverfolgt. Insgesamt werden bei dem Proof of Concept mehr als 3300 Identifikationsprozesse ohne Fehler durchgeführt. Abschließend werden die Erkenntnisse zusammenfassend diskutiert und Maßnahmen aufgezeigt, um die Identifikationssicherheit in Bezug auf die markierungsfreie Einzelteilverfolgung zu steigern.

Zusammenfassung

Als Schlüsselelement für die Realisierung der Vierten Industriellen Revolution – auch Industrie 4.0 genannt – ist die umfassende Erfassung von Zustandsdaten von Fabriken, Anlagen, Maschinen und Maschinenelementen und deren Umfeld notwendig. Die hierfür erforderlichen Sensoren müssen vernetzbar und in großer Stückzahl, sowie mit hoher Lebensdauer verfügbar sein. Die Einsatzorte dieser Sensoren sind häufig unzugänglich oder in rauer Umgebung, sodass industrierobuste Energieversorgungen über Kabel oder Batterie teils nur mit hohem Kostenaufwand möglich sind. Primär- und sekundärbatteriebasierte Systeme erweisen sich neben den Initialkosten auch bedingt durch den Wartungsaufwand als kostspielig hinsichtlich der Lebensdauerzykluskosten. Energy-Harvester können basierend auf der Umwandlung von Vibrationen oder Schocks in elektrische Energie eine energetisch unbegrenzte Lebensdauer ermöglichen. Diese Arbeit befasst sich mit der Integration derartiger kinetischer Umgebungsenergiewandler in Sensorsysteme für künftige Industrie 4.0-Anwendungen.

Zusammenfassung

In der vorliegenden Arbeit werden Schichtsysteme für mittels LPKF-LDS®-Verfahren aufgebauten Molded Interconnect Devices (LDS-MID) mit erhöhter Biegewechselfestigkeit entwickelt und bewertet. In einer grundlegenden Vorbetrachtung wird zunächst eine Methode für die Charakterisierung der wichtigen Schichteigenschaft der Haftfestigkeit erarbeitet und deren Überlegenheit gegenüber etablierten Haftfestigkeits-Messmethoden gezeigt. Im Rahmen von Charakterisierungen zur Biegewechselfestigkeit von LDS-Schichten werden unterschiedliche Einflussfaktoren, wie zum Beispiel Schichtrauheit und Schichtdicke, experimentell untersucht und bewertet. Es zeigt sich, dass nickelfreie Schichten eine deutlich erhöhte Biegewechselfestigkeit gegenüber dem etablierten Schichtsystem Cu/Ni/Au aufweisen. Darauf aufbauend werden die alternativen Schichtsysteme Cu/Ag und Cu/Pd/Au für die Abscheidung auf LDS-MID-Substraten erarbeitet und deren erhöhte Biegewechselfestigkeit gegenüber dem Schichtsystem Cu/Ni/Au verifiziert. Es zeigt sich weiter, dass sich mit den erarbeiteten alternativen nickelfreien Schichtsystemen feinste Leiterbahnpitches und Rapid Prototyping– Anwendungen für LDS-MID realisieren lassen.

Zusammenfassung

Diese Arbeit befasst sich mit der Herstellung von mikrostrukturierten Kunststoffoptiken mittels Spritzgießen. Dabei wurden drei Prozessketten entwickelt. Jede Prozesskette verwen- det unterschiedliche Verfahren zur Herstellung eines mikrostrukturierten Werkzeugeinsatzes, welcher anschließend für die Replikation mittels Spritzgießen eingesetzt werden kann. Der Spritzguss wurde dabei im Spritzprägeverfahren durchgeführt, welches häufig im Bereich Optikspritzguss eingesetzt wird. Die erste Prozesskette beschäftigt sich mit der Mikrostrukturierung mittels Ultrapräzisi- onsbearbeitung am Beispiel der Herstellung von Mikrolinsenarrays. Dabei wird im ersten Schritt ein Werkzeugeinsatz mittels Ultrapräzisionsbearbeitung gefräst und anschließend die optischen Bauteile im Spritzprägeverfahren repliziert. Für die Herstellung des Werkzeugein- satzes wurde eine Frässtrategie entwickelt, die es ermöglicht, hochpräzise Mikrolinsen in einen Werkzeugeinsatz zu integrieren. Dabei wurden 12.000 Mikrolinsen auf einer Fläche von 13x15 mm² hergestellt, wobei die Oberflächenqualität der einzelnen Linsen Ra < 10 nm betrug. Das spritzgeprägte Mikrolinsenarray hatte eine Bauteildicke von 500 μm, wobei die sehr hohe Oberflächenqualität der einzelnen Linsen von Ra < 10 nm beibehalten werden konnte. Die Funktionsfähigkeit der hergestellten Mikrolinsenarray konnte in einem hyper- spektralen Kamerasystem demonstriert werden. Die zweite Prozesskette beschreibt die Mikrostrukturierung mittels Laserdirektschreiben anhand der Herstellung eines diffraktiven optischen Elementes, welches als Nullbrechkraf- telement ausgelegt wurde. Das hergestellt Element besaß dabei zwei gekrümmte Flächen, wovon eine asphärisch und die andere mikrostrukturiert war. Der benötigte strukturierte Werkzeugeinsatz wurde mittels Laserdirektschreiben strukturiert. Dabei wurde eine Mas- terstruktur auf einer gekrümmten Glaslinse erzeugt. Anschließend wurde durch Galvanoko- pieren ein fester Werkzeugeinsatz hergestellt und in ein Spritzprägewerkzeug integriert. Durch die Replikation im Spritzprägeverfahren konnten die diffraktiven Strukturen mit einer Stufenhöhe von 1,65 μm abgeformt werden. Die Funktionsfähigkeit der hergestellten diffrak- tiven optischen Elemente konnten in einem chromatisch konfokalen Messaufbau gezeigt werden. Die Beugungseffizienz der Elemente betrug 73 %. Die dritte Prozesskette befasst sich mit der Herstellung von mikro- und nanostrukturier- ten Bauteilen mittels Spritzprägen. Hierfür wurde eine neuartige Prozesskette etabliert, welche das direkte Strukturieren eines Titan-Werkzeugeinsatzes mittels Ionenstrahlschreiben verwendet. Dadurch konnten Strukturen im Sub-Mikrometerbereich erzeugt werden, welche anschließend im Spritzprägeverfahren in ein Kunststoffbauteil übertragen wurden. Als Mikro- strukturen wurden zum einen Teststrukturen und zum anderen ein diffraktives optisches Element hergestellt. Die Funktionsfähigkeit der dabei hergestellten DOE-Strukturen konnte in einem Versuchsaufbau demonstriert werden. Neben der Entwicklung der drei Prozessketten wird in dieser Arbeit eine Auswahlhilfe für Technologien zur Herstellung von optischen Werkzeugeinsätzen präsentiert. Diese unterstützt die Auswahl einer geeigneten Technologie, wenn ein Werkzeugeinsatz für optische Anwendungen hergestellt werden soll. Dabei wird zwischen mikrostrukturierten und nicht strukturierten Werkzeugeinsätzen unterschieden. Eine ausführliche Erläuterung der Techno- logien beschreibt dabei zusätzlich die Möglichkeiten der einzelnen Technologien sowie deren Einschränkungen.

Zusammenfassung

Diese Arbeit behandelt die Zuverlässigkeitsuntersuchung und die numerische Modellierung von LEDs auf räumlichen Schaltungsträgern. Ziel dieser Untersuchungen ist die Erstellung von Lebensdauermodellen, welche sowohl zur Lebensdauerprognose als auch zur Ableitung von Design Rules angewendet werden. Der experimentelle Teil beinhaltet eine umfassende thermische Materialcharakterisierung der verwendeten räumlichen Schaltungstrager. Ein Aufbau wurde konzipiert und aufgebaut, welcher Aussagen über das Langzeitverhalten von LEDs ermöglicht. Die LEDs wurden unter unterschiedlichen Betriebsbedingungen getestet. Als Ergebnis zeigen die untersuchten MID-Materialien ein besseres Entwärmungspotential im Vergleich zur Standardleiterplatte. Weiter wurden drei numerische Ansätze zur Ermittlung der Sperrschichttemperatur verfolgt. Die thermisch stationäre Analyse basiert auf Randbedingungen aus dem Experiment, berücksichtigt die prozessbedingte Anisotropie der thermischen Eigenschaften aber nicht. Die entwickelte gekoppelte Simulationsmethodik berücksichtigt hingegen den Fertigungsprozess und somit die Füllstofforientierung. Die vorgeschlagene thermisch transiente Analyse basiert auf transienten Messungen und darauffolgender Modellkalibrierung. Aus den experimentellen Untersuchungen konnte unter Nutzung der Arrhenius-Gleichung ein Lebensdauermodell aufgestellt werden. Mithilfe der numerischen Ansätze und auf Basis der Arrhenius-Gleichung wurden Lebensdauerprognosen für LEDs sowohl auf planaren als auch auf 3D-Substraten getroffen. Die thermisch stationäre Analyse liefert gute Prognosen im Fall von LEDs auf planaren Substraten, ist aber im Fall von LEDs auf 3D-Substraten nicht anwendbar. Sowohl die gekoppelte Simulationsmethodik als auch die thermisch transiente Analyse können unabhängig von der Substratgeometrie angewendet werden. Anhand der gewonnenen Erkenntnisse konnten Design Rules abgeleitet und somit zeit- und kostenintensiver experimenteller Aufwand reduziert werden.

Zusammenfassung

Die vorliegende Dissertation beschreibt ein neuartiges, lasergestütztes Verfahren zur selektiven Metallisierung dreidimensionaler keramischer Bauteile. Dieses kann für die Herstellung elektronischer Schaltungsträger bzw. mechatronischer Baugruppen eingesetzt werden kann. Die Formgebung der Substrate erfolgt dabei mittels Keramikspritzguss. Durch einen speziellen Sinterprozess wird die Laseraktivierbarkeit der Keramiksubstrate gewährleistet. Daher sind für die Aktivierung keine zusätzlichen Additive im Keramikgefüge erforderlich. Während der Laserstrukturierung der gewünschten Leiterbilder erfolgt eine Aktivierung der keramischen Bauteile in den strukturierten Bereichen. Dadurch weisen die Bereiche eine katalytische Wirkung auf und ermöglichen die Abscheidung unterschiedlicher Metallschichtfolgen mittels außenstromloser chemischer Metallisierung. Die auf diese Weise metallisierten Keramikträger können im Anschluss mit elektronischen Bauelementen bestückt werden. Im Gegensatz zu den meisten herkömmlichen additiven Metallisierungsverfahren für Keramiken können mit der hier entwickelten lasergestützten Methode dreidimensionale keramische Schaltungsträger realisiert werden. Die abgeschiedenen Metallleiterbahnen bestehen vorwiegend aus der Metallschichtfolge Cu/Ni/Au mit den ungefähren Schichtdicken von 8 µm, 5 µm und 0,1 µm und zeigen eine sehr hohe Haftfestigkeit von bis zu 30 MPa. Die Haftfestigkeitswerte lassen eine hohe Zuverlässigkeit der abgeschiedenen Leiterbahnen erwarten, was durch die Ergebnisse der Zuverlässigkeitsuntersuchungen belegt wird. Die Oberflächenrauheit Rz der Metallschichten liegt im Bereich zwischen 8 µm und 15 µm und verspricht die Anwendbarkeit von Aufbau- und Verbindungstechniken wie zum Beispiel dem Dünndrahtbonden. Dies wird durch Machbarkeitsuntersuchungen nachgewiesen. Anhand zweier Demonstratorbauteile wird weiterhin die Herstellbarkeit von keramischen Schaltungsträgern für die Medizintechnik sowie der Aufbau dreidimensionaler Keramikbauteile dargelegt. Aufgrund der vorteilhaften Eigenschaften keramischer Materialien in Verbindung mit der dreidimensionalen Formgebung erlaubt das in dieser Arbeit entwickelte und vorgestellte Verfahren die Erschließung neuer Einsatzgebiete für elektronische Schaltungsträger.

Zusammenfassung

Die vorliegende Arbeit behandelt die Porenbildung und den Einfluss der Poren auf die Zuverlässigkeit von SMD-Lötstellen auf MID- und FR4-Substraten sowie von Bumplötungen auf FR4 unter thermischer Wechselbelastung. Im ersten Teil der Arbeit wurden experimentelle Untersuchungen der Porenbildung in den Lotdepots, SMD- und Bumplötstellen durchgeführt. Die Ergebnisse für Lotdepots aus SAC305 zeigen, dass die Porenbildung in Lotdepots signifikant von der Auswahl der Oberfläche abhängt. Der mittlere Porenflächenanteil im Standoff der CR0805-, MLF20- und Schalterlötstellen auf allen Substrattypen und für alle Lötverfahren lag im Bereich 0 bis maximal 15 %. Der anschließende beschleunigte Temperaturwechseltest nach JESD22-A104D mit einem Temperaturhub von 45°C bis +125°C belegte, dass für keine Kombination des SMD- und Substrattyps ein signifikanter Zusammenhang zwischen dem Porenanteil und der charakteristischen Lebensdauer vorlag. Um Aussagen über den nachweisbaren Porenanteil in CR0805-Lötstellen treffen zu können, wurden im zweiten Schwerpunkt dieser Arbeit auf Basis der experimentellen Untersuchungen FEM-Simulationen durchgeführt. Ein bis auf 50 % Porenflächenanteile erweitertes probabilistisches Modell demonstrierte mit dem steigenden Porenanteil einen Trend zu einer geringeren Zuverlässigkeit der Lötstellen, aber dieser Trend ist unter Berücksichtigung der Vertrauensbereiche erst für Porenanteile ≥ 40% signifikant. Bei MID auf FR4-Baugruppen wurden Bumplötungen mit den mittleren Porenflächenanteilen von 0 bis 15,3 % realisiert. Es zeigt sich, dass durch die Geometrieänderung der Bumpkontaktierungen die Porenbildung sowohl im Standoff als auch im Meniskus der Lötstelle reduziert werden kann. Die Ergebnisse des beschleunigten Temperaturwechseltests von -45°C bis +125°C an diesen Baugruppen demonstrieren einen signifikanten Zusammenhang zwischen dem Porenflächenanteil und der charakteristischen Lebensdauer. Im Rahmen der Sensitivitätsanalyse zur Bildung eines probabilistischen Modells für MID auf FR4-Baugruppen wurden aus zwölf Geometrie- und Materialparametern nur drei als signifikant eingestuft. Das nachfolgende DoE belegte, dass die Poren im Meniskusbereich einen großen Einfluss auf die Lebensdauer aufweisen. Insgesamt können die probabilistisch aufgestellten Lebensdauermodelle für MID auf FR4-Baugruppen den experimentell nachgewiesenen Einfluss der Poren auf die Zuverlässigkeit gut wiedergeben

Zusammenfassung

The Molded Interconnect Devices (MID) technology offers a high potential for the miniaturization of multifunctional three dimensional plastic devices in communication, medical technology, automotive applications, mechanical engineering and in industrial automation. Manufacturing flexibility, design freedom in three dimensional as well as high mechatronic integration density are the main characteristics underlining the potential of these technologies. Today, textual information for blind people are provided by speech synthesizers or Braille lines. The needs of blind people grow with the evolution of computer applications beyond pure speech applications. The major disadvantage of electronic Braille lines is that only textual information can be provided. Two dimensional electronic Braille displays have been designed, which consist of novel Braille modules to present graphical information. In each Braille module, pins are driven by 10 piezo actuators at a voltage of 200 V each. Furthermore in each novel module touch sensors are needed, emulating the function of a computer mouse. Additionally, each module requires an integrated circuit with two bare die ASICs and several SMDs for controlling the piezo actuators and the touch sensor as well. For such highly integrated Braille modules the application of MID technologies combining miniaturization with high functionality is very promising. Due to the costs and metal line pitch of the tooling the 2-shot injection molding is not suited. The hot embossing MID is not suited because it is restricted to planar metal line layout through the stamp geometry, namely only plain surfaces can be processed. Laser based MID technologies such as the laser semi additive (LSA) and the laser direct structuring (LDS) processes are particularly suitable for the complex three dimensional circuitry of the novel MID Braille modules. This thesis describes the series production of novel mechatronic Braille modules using two MID technologies, the LSA and LDS technology. Manufacturing implementation and quality concepts were developed and used. During each process phase a quality control step has been performed on each Braille module. All test data was compiled in a data base system, therefore it was possible to monitor the yield of the modules e.g. failure causes and failure rate. A total of 12.563 modules in LSA technology and a total of 5.489 modules in LDS technology were processed.

Zusammenfassung

Durch die Megatrends Sensors Everywhere, Internet of Things, Cyber Physical Systems, Industrie 4.0 und Ambient Assisted Living steigt der Bedarf an Sensoren und Sensorsystemen. Neue Fertigungstechnologien und Sensordesigns werden in diesem Kontext benötigt um die steigenden Anforderungen an die Sensoren erfüllen zu können. Der Inkjetdruck und die Sinterung von nanopartikelbasierten Silbertinten auf Kunststoffsubstraten könnte eine dieser neuen Fertigungstechnologien sein, da solche inkjetgedruckten Silberstrukturen als Temperatursensoren eingesetzt werden könnten. In dieser Arbeit wurde der Aufbau von Temperatursensoren auf Foliensubstraten und spritzgegossenen thermoplastischen Substraten mittels Inkjettechnologie anhand zweier Anwendungsbeispielen untersucht. Als Funktionsmaterial wurden für beide Anwendungsbeispiele eine nanopartikuläre Silbertinte eingesetzt. Um Temperatursensoren für die Anwendungsbeispiele aufbauen zu können, wurden zu Beginn die Einflussfaktoren auf die Eigenschaften der gedruckten Silberstrukturen wie z.B. der Druck- und Sinterprozess auf Polyimidfolie und spritzgegossenen thermoplastischen Substraten untersucht und optimiert. Hierbei fand auch eine neuartige Sinterung von Silbertinte mittels UV-Strahlung Anwendung. Die gedruckten Silberschichten wurden nach dem Sintern unter anderem in Bezug auf den elektrischen Widerstand und das Temperaturverhalten charakterisiert. Vor allem inkjetgedruckte Leiterstrukturen auf spritzgegossenen thermoplastischen Substraten waren bisher nur unzureichend untersucht. Hierzu wurde der Einfluss der Glasfasern, der anisotropen Eigenschaften und der erhöhten Substratrauheit untersucht. Basierend auf den Ergebnissen wurden für beide Anwendungsbeispiele Aufbaukonzepte für gedruckte Temperatursensoren erarbeitet. Abschließend wurden gedruckte Temperatursensoren aufgebaut und bezüglich ihrer Anforderungen aus den Anwendungsbeispielen charakterisiert und evaluiert.

Zusammenfassung

Durch die Megatrends Sensors Everywhere, Internet of Things, Cyber Physical Systems, Industrie 4.0 und Ambient Assisted Living steigt der Bedarf an Sensoren und Sensorsystemen. Neue Fertigungstechnologien und Sensordesigns werden in diesem Kontext benötigt um die steigenden Anforderungen an die Sensoren erfüllen zu können. Der Inkjetdruck und die Sinterung von nanopartikelbasierten Silbertinten auf Kunststoffsubstraten könnte eine dieser neuen Fertigungstechnologien sein, da solche inkjetgedruckten Silberstrukturen als Temperatursensoren eingesetzt werden könnten. In dieser Arbeit wurde der Aufbau von Temperatursensoren auf Foliensubstraten und spritzgegossenen thermoplastischen Substraten mittels Inkjettechnologie anhand zweier Anwendungsbeispielen untersucht. Als Funktionsmaterial wurden für beide Anwendungsbeispiele eine nanopartikuläre Silbertinte eingesetzt. Um Temperatursensoren für die Anwendungsbeispiele aufbauen zu können, wurden zu Beginn die Einflussfaktoren auf die Eigenschaften der gedruckten Silberstrukturen wie z.B. der Druck- und Sinterprozess auf Polyimidfolie und spritzgegossenen thermoplastischen Substraten untersucht und optimiert. Hierbei fand auch eine neuartige Sinterung von Silbertinte mittels UV-Strahlung Anwendung. Die gedruckten Silberschichten wurden nach dem Sintern unter anderem in Bezug auf den elektrischen Widerstand und das Temperaturverhalten charakterisiert. Vor allem inkjetgedruckte Leiterstrukturen auf spritzgegossenen thermoplastischen Substraten waren bisher nur unzureichend untersucht. Hierzu wurde der Einfluss der Glasfasern, der anisotropen Eigenschaften und der erhöhten Substratrauheit untersucht. Basierend auf den Ergebnissen wurden für beide Anwendungsbeispiele Aufbaukonzepte für gedruckte Temperatursensoren erarbeitet. Abschließend wurden gedruckte Temperatursensoren aufgebaut und bezüglich ihrer Anforderungen aus den Anwendungsbeispielen charakterisiert und evaluiert.

Zusammenfassung

Diese Arbeit behandelt Untersuchungen zur kostengünstigen Herstellung eines dreidimensionalen spritzgegossenen Schaltungsträgers mittels Inkjet-Verfahrens durch Drucken einer Tinte mit metallischen Silbernanopartikeln. Als Anwendungsbeispiel diente ein Intrusionssensor, der nach Stand der Technik mit dem etablierten LPKF-LDS®-Verfahren hergestellt wird. Die Intrusionssensoren bestehen aus einer Kunststoffabdeckhaube mit dichten, komplexen mäanderförmigen Leiterbahnstrukturen. Hierzu wurden die geometrischen Eigenschaften der gedruckten Silberstrukturen auf flachen und geneigten flachen Oberflächen der spritzgegossener Substrate sowie das Drucken über die Kanten mit entsprechenden Radien untersucht. Weiterhin wurde die Haftfestigkeit der gedruckten Silberstrukturen auf den spritzgegossenen Substraten qualitativ mittels Tape-Test untersucht. Für die quantitative Bestimmung der Haftfestigkeit wurde der Schertest auf die Anforderungen der gedruckten Strukturen optimiert. Auf spritzgegossenen Substraten lassen sich feine gedruckte Strukturen mit glatten Kanten realisieren, die eine gute Haftung aufweisen. Des Weiteren wurden Anforderungen an den Druckprozess zum Bedrucken einer Kunststoffabdeckhaube erarbeitet. Bei der Gegenüberstellung der Konzepte hat sich das Drucken mit erhöhtem Druckabstand als potentiell beste Lösung hervorgehoben, woraufhin dies detaillierter untersucht wurde. Hierbei wurden verschiedene Einflüsse sowohl durch Versuche als auch durch eine theoretische Betrachtung analysiert. Hierbei zeigte sich der Druckkopf als der ausschlaggebende Faktor für die Tropfenpositionsgenauigkeit. Basierend auf Ergebnissen zum Drucken mit erhöhtem Druckabstand wurde für die Kunststoffabdeckhaube ein Druckprozess erarbeitet. Konzepte für eine sichere Ankontaktierung der gedruckten Leiterbahnstrukturen mit der Peripherie wurden ebenfalls erarbeitet. Das Konzept mit dem Einsatz des Inkjet-Verfahrens zur Vereinfachung der Kontaktstelle wurde im Rahmen einer Voruntersuchung getestet. In dieser Arbeit konnte mit dem Inkjet-Verfahren ein Intrusionssensor hergestellt werden und somit neue Möglichkeiten für den Einsatz des Inkjet-Verfahrens aufgezeigt werden.

Zusammenfassung

Für Moulded Interconnect Devices (MID) bzw. spritzgegossene Schaltungsträger stellt die elektrische Verbindung des MID zum peripheren System nach wie vor eine große technologische Herausforderung dar, da die Kosten und Zuverlässigkeit der kompletten Systeme wesentlich durch diese Schnittstelle bestimmt werden. Die elektrische Kontaktierung zwischen MID und dem peripheren System über elektrische Leiter erfolgt derzeit meistens über Lötverbindungen. Dabei ist hervorzuheben, dass sich zur peripheren Kontaktierung noch keine Standards entwickelt haben, d.h. für jede Produktentwicklung muss zusätzlich ein großer Aufwand zur Entwicklung der elektrischen Kontaktierung des MID mit der Peripherie aufgebracht werden. Im Rahmen dieser Arbeit erfolgt die systematische Erarbeitung von Grundlagen zu kraft- und stoffschlüssigen Verfahren zur peripheren elektrischen Kontaktierung von MID, die bisher noch nicht industriell eingesetzt werden. Wegen der guten Automatisierbarkeit, der kurzen Prozesskette und der hohen Verbreitung bei Leiterplatten wurde einerseits die kraftschlüssige Kontaktierung von MID mittels Einpresstechnik für die wichtigen Verbindungen der MID mit Steckverbindern oder Leiterplatten untersucht. Andererseits wurde die stoffschlüssige Kontaktierung mittels Widerstandsschweißen ausgewählt, die eine einfache Kontaktierung von MID-Baugruppen ohne Verwendung von Fügematerialien wie Loten oder Leitklebern sowie ohne zusätzliche Komponenten wie beispielsweise Stecker oder Klemmvorrichtungen bei gleichzeitig hoher mechanischer Festigkeit und hoher thermischer Belastbarkeit der Verbindungsstellen ermöglicht. Zu Beginn werden die theoretischen Grundlagen erarbeitet um Rückschlüsse auf die Einflussfaktoren der Prozessführung sowie auf die Kontaktierung zu erhalten. Aufbauend auf diesen Erkenntnissen werden experimentelle Untersuchungen auf MID-Substraten durchgeführt, die mit den MID-Strukturierungsverfahren LPKF-LDS®- und Heißprägetechnik hergestellt wurden. Weiterhin wurde die Anwendbarkeit der vorhandenen normativen Richtlinien zur Charakterisierung der untersuchten Kontaktierungsverfahren überprüft. Die Zuverlässigkeit der Kontaktierungen wurde u.a. anhand von beschleunigten Umwelttests untersucht. Abschließend wurde die industrielle Umsetzbarkeit der untersuchten Verfahren bewertet.

Zusammenfassung

Diese Arbeit behandelt Zuverlässigkeitsuntersuchungen und rechnergestützte Modellierung von gelöteten SMD auf spritzgegossenen Schaltungsträgern unter thermischer Wechselbelastung. Die verwendeten MID Substratmaterialien waren die LDS Thermoplaste Pocan DP T7140 LDS, Ultramid T4381 LDS und Vectra E840i LDS. Diese sind hinsichtlich ihrer thermomechanischen Materialeigenschaften längs und quer zur Faserorientierung aus dem Spritzgussprozess sowie ihrer zeitabhängigen elastischen Materialeigenschaften charakterisiert worden. Zur Bestimmung der Zuverlässigkeit wurden geeignete elektronische Bauteile ausgewählt und mittels eines SAC305 Lots auf die Testsubstrate gelötet. Die gewählten Bauteile waren die Kunststoffgehäusetypen MLF20 und SO8 sowie die Keramikwiderstände der Typen CR1206, CR0805 und CR0603. Ein Temperaturschocktest ist im Temperaturbereich zwischen -40°C (-10/+0°C) und 125°C (-0/+15°C) mit 20 min Haltezeit durchgeführt worden. Die Widerstände der verschiedenen Bauteile wurden mittels einer Online-Widerstandsmessung überwacht. Nach den Tests ist eine detaillierte Fehleranalyse durchgeführt worden. Dabei wurden die Ausfallursachen der gelöteten SMD auf MID bestimmt und bewertet. Die statistische Auswertung der Ausfälle erfolgte mittels der 3-Parameter Weibullverteilung. Die durchgeführten Untersuchungen ermöglichten einen Vergleich der Zuverlässigkeiten zwischen MID und FR-4. Weiter wurde der Einfluss unterschiedlicher Modellierungsansätze für MID Substratmaterialien auf Lebensdauermodelle von Lötverbindungen untersucht. Hierfür wurden unter anderem thermomechanische FEM-Simulationen unter Verwendung der Daten aus Spritzgusssimulationen eingesetzt. Die berechneten Risspfade in den Lötverbindungen sind mit den experimentellen Ergebnissen verglichen worden. Die Lebensdauermodelle für die Lötverbindungen wurden mit Nutzung der Coffin-Manson Beziehung erstellt und hinsichtlich der Güte der Anpassung von Simulation und Experiment sowie der Aussagefähigkeit von Lebensdauerprognosen für 3D-MID Anwendungen bewertet.

Zusammenfassung

Laserbasierte Herstellung von Vias in MID: Große Anwendungspotentiale der MID Technik sehen Experten in der Sensortechnik, bei Antennen und bei der 3D-Verdrahtung. Dies sind Anwendungen in Bereichen, in denen die Miniaturisierung einen hohen Stellenwert hat. Die Verwendung von elektrischen Durchkontaktierungen könnte bei vielen potentiellen Anwendungen zur Miniaturisierung beitragen. Der Einsatz von Vias bietet die Möglichkeit Kreuzungen von Leiterbahnen zu realisieren. Abhängig von der spezifischen Anwendung sind als weitere Vorteile u.a. der geringere Platzbedarf, die Möglichkeit Verbindungen auf der gesamten Bauteilfläche ausführen zu können und eine bessere Schirmung zu nennen. Ein Inhalt dieser Arbeit ist daher die Erarbeitung und Untersuchung verschiedener laserbasierter Prozesse zur Herstellung von Vias in MID. Der Schwerpunkt liegt dabei auf dem IR-Laserbohren von Durchdringungen beim LDS-Prozess. Die Laser-Direkt-Strukturierung von spritzgegossenen Durchdringungen und die Kombination von UV-Laserbohren mit dem semiadditiven LSA-Prozess werden ebenfalls betrachtet. Wichtige Einflussfaktoren auf die Qualität und Zuverlässigkeit gefertigter Vias werden identifiziert und daraus über die gesamte Fertigungskette hinweg geeignete Prozessparameter abgeleitet. Möglichen Anwendern soll so das Potential von Vias in MID aufgezeigt werden. Gleichzeitig möchte diese Arbeit sie bei der praktischen Realisierung unterstützen. Neuartiges Messprinzip zur Badcharakterisierung von außenstromlosen Kupferelektrolyten: Für die Kupferbeschichtung von Substraten nach der Laseraktivierung werden spezielle Kupferelektrolyte eingesetzt. Die Führung der Bäder erfordert viel Erfahrung, insbesondere das Einstellen der optimalen Badreaktivität ist schwierig und hat einen großen Einfluss auf die Qualität der MID. Vor allem bei sehr reaktiven Bädern kann die Messdauer etablierter Verfahrens zu lang sein um gegensteuern zu können oder um den Metallbeschichtungsprozess im Fehlerfall zu stoppen. Ein weiterer Inhalt dieser Arbeit ist die Erarbeitung, Charakterisierung und Qualifizierung eines neuartigen Messprinzips zur Bestimmung der Badreaktivität von außenstromlosen Kupferelektrolyten. Es wird ein einfach handhabbares Messsystem vorgestellt und dessen Eignung zur Badführung und -regelung nachgewiesen. Durch Vergleichsmessungen wird die Korrelation mit etablierten Verfahren geprüft.

Zusammenfassung

This work deals with hot embossing technology, a fast and simple method for MID-manufacturing. Though industrially used for many years, there are still some issues to improve. The endurance of hot embossing stamps is limited to approximately 800 embossing cycles, than the stamp surface is contaminated and the stamp has to be removed for cleaning. With hard coatings deposited by PVD or PECVD processes the endurance of the stamps could be increased significantly. The investigations show that best results were achieved with DLC coatings, with which up to 4000 embossing cycles were performed without intermediate cleaning step. For building circuits electrodeposited Cu-foils (ED-foils) are commonly used, the more reasonable rolled and annealed foils (RA-foils) so far are not accessible for hot embossing, because the conductor lines are not separated from the foil during the press cut. In order to make RA-foils still accessible for hot embossing, a process was developed, which pre-cuts the conductor lines with laser technique. It was found, that small fixed links along the cut are the best solution for handling and good embossing results. The feasibility of the technology was evaluated on functional MID-devices. Hot embossing for circuit manufacturing so far is limited to rigid boards, the process conditions normally leads to a strong deformation of flexible materials. In this work new high temperature resistant flex-materials were investigated and the hot embossing equipment was improved. It could be demonstrated, that with an optimized stamp design and an anvil equipped with vacuum fixation and temperature regulation the warpage of the thin foils could be reduced almost completely and flexible circuits could be produced in good quality. Finally a process for manufacturing of two layer circuits on thin flexible foils with micro welded interconnects was developed successfully.

Zusammenfassung

An advanced optical rotary encoder concept is presented within this work. The basic idea is to use a micro structured plastic disk as code wheel which is manufactured by injection moulding. The solid measure consists of micro structures which act like a diffraction grating. To industrialize this concept, a compact incremental and also an absolute encoder were designed and manufactured. The incremental encoder has a diameter of 36,5 mm and a height of 29 mm with a resolution of 2048 increments per revolution. The code wheel with a diameter of 30 mm is made of polycarbonate. The design concept is to use an optical MID (Moulded-Interconnect-Device) module which contains a laser diode and photodiodes as well as a lens and an aperture. Due to the precise MID module it is possible to assemble the encoder without any steps of adjustment. The absolute encoder requires small dimensions of only 16 x 16 x 18 mm³ with a resolution of 6 bit. The code wheel with a diameter of 9 mm is made of PEEK. PEEK was necessary due to high temperature requirements of the whole encoder during an optional reflow soldering process at 260°C. The optical components like laser diode, photodiode array and aperture were directly integrated in an optical module with dimensions of 5 x 5 x 1,6 mm³ similar to an QFN package. In case of larger quantities it is also possible to develop an Opto-ASIC with integrated photodiodes and signal processing. In this way, a small miniaturized low cost encoder module can be manufactured. The experimental characterization of the encoders was performed on a test bench for rotary encoders. The influence under temperature during operation of the encoder was investigated from -40° to +85°C in an environmental test chamber. It could be shown that the influence is insignificant if the power of the laser diode is regulated by a monitor diode. Without power regulation the signals decrease about 50% at high temperatures. Furthermore, comprehensive investigations regarding the tolerances of the encoder assembling have been done. For example the distance of the encoder disc has to be within a tolerance range of ±100 µm. For both encoder types several prototypes have been assembled without any adjustment. All correctly assembled encoders were working without failures. This shows that the encoding method with diffraction gratings on a plastic code wheel can be used to build up miniaturized optical low cost encoders with high resolution.

Zusammenfassung

Es gibt derzeit keine am Markt erhältlichen Geräte, die sowohl unbegrenztes Dosiervolumen verabreichen können als auch den genannten Ratenbereich mit der geforderten Genauigkeit abdecken. Um den Geräteaufwand zu minimieren, ist es deshalb eine wichtige Anforderung an eine neuartige Infusionspumpe, diese universell einsetzen zu können. Das ist in dieser Arbeit vorgestellte neuartige Pumpprinzip mit ferromagnetischem Pumpelement stellt eine Verfeinerung des Hubkolbenprinzips dar und ist aufgrund seines einfachen und robusten Aufbaus für die Ausführung als Einwegteil in der Medizintechnik geeignet. Der zur Bewegung des Pumpelements nötige Antrieb kann ebenfalls sehr einfach und mit wenigen Bauteilen ausgeführt sein. Er kommt dabei nicht mit dem zu fördernden Fluid in Kontakt. In medical infusion technology there is a wide range of applications with each of them putting specific demands on the infusion pump, such as accuracy and range of delivery rates. While for parenteral feeding high delivery rates with lower demands on accuracy are needed, very low delivery rates and high demands on accuracy are required in intensive-care medicine. There are different types of pump systems in use to cover the whole range of applications in infusion therapy. Currently there is no solitary infusion pump which can cover all applications with its specific demands. In this thesis is introduced a new pumping concept with disposable pump unit for usage in medical technology. The goal is to show its usability for high accuracy infusion pumps with a very large range of delivery rates.

Zusammenfassung

Diese Arbeit stellt Untersuchungen zu einem neuartigen, miniaturisierten Schaltventil mit Medientrennung und Stoßantrieb vor. Das Schaltventil zeichnet sich dadurch aus, dass die Medientrennung ohne Dichtelemente erreicht wird, da der fluidbenetzte Bereich, die sog. Ventilkammer, abgesehen vom Einlass und Auslass ein abgeschlossenes Volumen darstellt. Die Ventilkammer beinhaltet ein bewegliches Element, welches den Strömungsweg durch die Kammer sperrt oder freigibt. Der Umschaltvorgang des beweglichen Elements und damit die Änderung des fluidischen Schaltzustands wird dabei durch einen Stoß von außen auf die Wand der Ventilkammer ausgelöst. Für die Antriebseinheit zur Erzeugung des Stoßes auf die Ventilkammer stehen verschiedene Konzepte und Wirkprinzipien zur Auswahl. Als Schnittstelle zwischen der Ventilkammer und der Antriebseinheit fungiert die Wand der Ventilkammer, durch welche die Stoßenergie von der Antriebseinheit auf das bewegliche Element im Inneren der Ventilkammer weitergeleitet wird. Zur Untersuchung und Optimierung des Ventilkonzepts wurden zunächst verschiedene Stoßantriebe mit Hilfe eines speziell entworfenen Messplatzes charakterisiert und optimiert. Darauf folgte die Konzeption der Ventilkammer nach dem Prinzip des methodischen Konstruierens. Anschließend wurde das Zusammenspiel von Ventilkammer und Antriebseinheit an zwei beispielhaften Ventilaufbauten gezeigt. Um die Untersuchung des Ventilkonzepts zielgerichtet durchführen zu können, flossen bei der Planung der Ventilaufbauten und bei der Bewertung der Ergebnisse bereits die Anforderungen einer Pilotanwendung des miniaturisierten Schaltventils ein. Es handelt sich dabei um die Hydrozephalus-Therapie, bei der miniaturisierte Schaltventile mit Medientrennung als aktives, implantierbares Drainageventil Verwendung finden und zu völlig neuen Therapieoptionen führen könnten.

Zusammenfassung

Miniaturisierte mechatronische Systeme sind heute eine tragende Säule für den Großteil der innovativen Produkte aus der Automobil-, Kommunikations-, Medizin- und Automatisierungstechnik. Als Triebfedern wirken dabei sowohl die kontinuierlich steigende Leistungsfähigkeit der elektronischen, mechanischen und informationsverarbeitenden Teilsysteme als auch die ansteigende Funktions- und Integrationsdichte sowie die fortschreitende Miniaturisierung der Systeme. Wurden mechatronische Systeme früher aus autarken, diskreten Subkomponenten über standardisierte Schnittstellen zusammengesetzt, begreift man heute das Gesamtsystem als Einheit und ist dadurch in der Lage die Leistungsfähigkeit und die Wirtschaftlichkeit immens zu steigern. Ein Werkzeug um dies zu Erreichen sind dreidimensionale spritzgegossene Leitungsträger, sogenannte moulded interconnect devices (MID). MID führen verschiedene Funktionalitäten in einem Bauteil zusammen, öffnen die dritte Dimension als funktionellen Bauraum und können damit die Systemgröße, die Anzahl der Verbindungselemente und Montageschritte, und schließlich die Kosten reduzieren. Ein weiteres wichtiges Verfahren zur Miniaturisierung mechatronischer Systeme ist die Direktmontage von ungehäusten Halbleiterbauelementen auf dem Schaltungsträger als Ersatz von gehäusten Bauteilen für die Oberflächenmontage. Das Drahtbonden ist dabei zwar das Verbindungsverfahren mit der größten Verbreitung, durch den Einsatz der Flip Chip Technik ist aber für Einzelchips eine zusätzliche Optimierung bezüglich Bauraumreduzierung, Anschlussdichte, Wärmeabfuhr und Hochfrequenzverhalten zu erreichen. Bei diesem Verfahren wird der Chip mit erhabenen Kontakthöckern, den sogenannten Bumps, versehen und mit der funktionellen Seite nach unten auf dem Schaltungsträger montiert. Aus den genannten Gründen ist es daher wichtig und notwendig, die Direktmontage für die 3D MID Technik nutzbar zu machen, um die potenziellen Vorteile voll ausschöpfen zu können. In dieser Arbeit werden verschiedene Verfahren der klebstoffbasierten Flip Chip Technik auf MID untersucht, verglichen und bewertet. Weiterhin wird ein neuartiges Verfahren zur Chipmontage auf spritzgegossenen MID Bumps vorgestellt und detailliert theoretisch und experimentell untersucht.

Zusammenfassung

Micro manufacturing involves dealing with the fabrication of structures in the size range of 0.1 to 1000 µm. The scope of nano manufacturing extends the size range of manufactured features to even smaller length scales—below 100 nm. A strict borderline between micro and nano manufacturing can hardly be drawn, such that both domains are treated as complementary and mutually beneficial within a closely interconnected scientific community. Both micro and nano manufacturing can be considered as important enablers for high-end products. This Special Issue of Applied Sciences is dedicated to recent advances in research and development within the field of micro and nano manufacturing. The included papers report recent findings and advances in manufacturing technologies for producing products with micro and nano scale features and structures as well as applications underpinned by the advances in these technologies.

Zusammenfassung

This chapter is meant to give an overview of capabilities and limitations of inkjet printing of functional structures on molded 2D and 3D substrates. Different injection-molded thermoplastics, transfer molded thermosets, and polyimide (PI) foil were used as substrate materials. Conductive structures were obtained by inkjet printing of commercially available silver nanoparticle inks. Results on inkjet-printed structures and devices such as temperature sensors, intrusion sensor conductor loops, or electrical interconnects and antennas on transfer-molded packages will be presented. Methods for the electrical interconnection of the printed structures with nonprinted conductive structures such as PCB contact pads are also discussed.

Zusammenfassung

Dieses Buch enthält Vorstudien für das Handbuch der Chronometrie und Uhrentechnik, Band II, Kapitel 5.7: Astronomische Uhren. Teile davon wurden im Jahrbuch der Deutschen Gesellschaft für Chronometrie veröffentlicht. Für die Zusammenstellung wurden astronomische Tabellen (Nautisches Jahrbuch, P. Ahnert, Das Himmelsjahr), Bücher über Astronomie und Uhren, insbesondere für Bilder (siehe die einzelnen Angaben) verwendet. Die Zeichnungen wurden meist selbst angefertigt. Die Vervielfältigung dieses Buches erfolgt nur in wenigen Exemplaren, um gegebenenfalls noch Korrekturen anzubringen. Falls solche notwendig sind, bin ich um entsprechende Mitteilung dankbar. Das Buch soll Grundlage für den Bau Astronomischer Uhren sein. Diese würde man heute nicht mehr mit komplizierten mechanischen Getrieben ausführen, sondern mit elektronischen Übersetzungen und einer weitgehenden digitalen Anzeige. Als Zeitbasis ist hierfür die möglichst durch Funk gesteuerte Quarzuhr geeignet. Frau Ingeborg Rahmig danke ich für die pünktliche und kritische Abfassung des Manuskriptes. Stuttgart im November 1989

Zusammenfassung

Es ist eine erfreuliche Gepflogenheit, daß die Chronometriegesellschaften von Frankrei, der Schweiz und von Deutschland alle 5 Jahre einen internationalen Kongreß veranstalten, ohwohl sich die einzelnen Gesellschaften jährlich ein- bis zweimal treffen. Bei dem CIC liegt jedoch die Betoung auf "international", um die Fachleute auf der ganzen Welt zu einer gemeinsamen Tagung zusammenzurufen und den Wunsch und Willen zur gemeinschaftlichen, wissenschaftlichen Zusammenarbeit zu bekunden. Wir freuen uns daher, daß 1974 die Deutsche Gesellschaft für Chronometrie diesen Kongreß in Stuttgart, der Hauptstadt des Uhrenlandes Baden-Württemberg, veranstalten kann und dß dem Ruf zur Teilnahme viele Fachleute aus vielen Ländern der Welt gefolgt sind. Dieser Kongreß soll eine Arbeitstagung sein, die auf dem Wunsch der Gesellschaften auf 4 Tage konzentriert wurde mit 3 bis 4 Parallel-Vortragssitzungen, die so eingeteilt sind, daß sich die fachlichen Interessen nicht allzusehr überschneiden. Die Vorträge in jedem der 6 Fachgebiete A bis F wurden im Kongreßbuch in je einem Teilband zusammengefaßt. Dabei wurden die Vorträge, die später in den Jahrbüchern der einzelnen Gesellschaften veröffentlich werden, auch von diesen Gesellschaften in der jeweiligen Form gedruckt. Auf dem Titelblatt der einzelnen Vorträge ist sowohl die Kongreß-Vortragsnummer vermerkt als auch die des betreffenden Jahrbuchs. Die Zusammenfassungen der Vorträge sind in einem besonderen Band enthalten. Wesentliche Diskussionsbemerkungen sollen später im Jahrbuch 1974 der DGF veröffentlicht werden. Die Leitung der Vortragssitzungen wird jeweils von 3 Fachleuten übernommen, um eine mehrsprachige Diskussion zu ermölgichen. Außer den fachwissenschaftlichen Vorträgen sind Exkusionen und eine Besichtung des Stuttgarter Uhreninstitutes vorgesehen. Möge auch das Rahmenprogramm mit der Übergabe der hervorragenden Uhrensammlung "Fremersdorf" und dem Gesellschaftsabend dazu beitragen, daß sich die Teilnehmer persönlich näher kennenlernen und damit der so wichtigen internationalen Verständigung dienen. Allen, die zum Gelingen des Kongresses beigetragen haben, den Vortragenden, Den Präsidenten der Gesellschaften, den verantwortlichen Herren, sei auch an dieser Stelle herzlich gedankt, ebenso wie den staatlichen Stellen und dem Verband der Deutschen Uhrenindustrie für ihre finanzielle Unterstützung. G. Glaser

Zusammenfassung

Das Institut für Mikrointegration (IFM) blickt in diesem Jahr auf sein 75-jähriges Bestehen zurück. Seit seiner Gründung im Jahr 1944 steht die Miniaturisierung technischer Systeme im Fokus. So befasst sich das IFM in Forschung und Lehre mit der Mikrotechnik und der Mikrosystemtechnik. Aktuelle Schwerpunkte reichen von der Sensorik als wichtigem Anwendungsgebiet der Mikrosystemtechnik über optische Mikrosysteme, folienbasierte „System-in-Foil“, räumliche Elektronik und digitale Prozessketten bis zu hochpräzisen Strukturierungsverfahren für die Mikrotechnik. Aus Anlass des 75-jährigen Jubiläums des IFM wurde diese Festschrift verfasst, die einen Einblick in die Geschichte des Instituts und in die aktuelle Ausrichtung von Forschung und Lehre bietet. Anstelle einer vollständigen Darstellung aller Veröffentlichungen werden ebenso die Themen der am Institut durchgeführten Dissertationen aufgelistet, um den inhaltlichen Wandel von der Zeitmesstechnik zur Mikro- und Mikrosystemtechnik zu dokumentieren. Aufgrund des interdisziplinären Charakters und der großen Bedeutung für gesellschaftliche Megatrends, die die Mikrosystemtechnik auszeichnen, bestehen für das IFM hervorragende Chancen, den eingeschlagenen Weg erfolgreich fortzusetzen und spannende wissenschaftliche und technologische Neuerungen zu erschließen.

Zusammenfassung

Der zu 90% im Raum Baden-Württemberg liegenden Uhrenindustrie war es in den wirtschaftlich schwierigen Jahren um 1930 ein dringender Wunsch, das Fachgebiet Uhrentechnik und Feinmechanik außer an den Fachschulen auch an einer deutschen Technischen Hochschule vertreten zu wissen, um sowohl einen Nachwuchs technischer Führungskräfte von dort zu erhalten, als auch die bisher meist empirisch gewonnenen Erkenntnisse auf diesem Fachgebiet durch wissenschaftliche Forschung zu untermauern. Daher regte, Dr. Helmut Junghans, Schramberg, zunächst bei der Notgemeinschaft der deutschen Wissenschaften und bei der Physikalisch-Technischen Reichsanstalt eine uhrentechnische Forschung an, die damals vor allem von Dr. W. Keil, Dr. E. Rieckmann und Dr. K. Hild durchgeführt wurde. Im Jahre 1940 konnte erreicht werden, daß an der Technischen Hochschule Stuttgart ein Lehrstuhl für Uhrentechnik, Zeitmeßkunde und Feinmechanik geschaffen wurde, auf den Professor Dr. W. Keil im Jahre 1944 berufen wurde. Die Kriegsjahre und erst recht die Nachkriegsjahre mit allen Nöten an Mitteln, Personal und Räumen waren für dieses Institut eine harte Zeit. Der wirtschaftliche Aufschwung nach 1950 und die Struktur der deutschen Uhrenindustrie mit ihren vielen mittleren und kleineren Firmen ließen bald die Notwendigkeit nach Erweiterung des Instituts erkennen; den nur so war eine industrielle Gemeinschaftsforschung für die deutsche Uhrenindustrie zu ermöglichen. Zu diesem Zweck wurde 1954, wiederum unter Führung von Dr. Helmut Junghans, die Forschungsgesellschaft für Uhren- und Feingerätetechnik gegründet, deren Zweck die Errichtung und der Betrieb eines Forschungsinstituts ist. Bei Gründung des Instituts wurde mit dem Landtag sowie mit dem Kultus- und Wirtschaftsministerium des Landes Baden-Württemberg eine enge Verbindung zwischen Universitätsinstitut und Forschungsinstitut vereinbart, die sich durch eine Personalunion in der Leitung, durch einen gemeinsam finanzierten Institutsbau, durch gemeinsame Benützung von Räumen, Geräten und einen engen fachlichen Gedankenaustausch ausdrückt. Unter wesentlicher Unterstützung des Verbandes der Deutschen Uhrenindustrie und der Wirtschaftsministerien von Land und Bund konnte das gemeinsame Gebäude 1959 fertiggestellt werden. Prof. Dr. W. Keil verstand es, mit seinen Assistenten das Institut mit modernen Geräten auszustatten und wichtige Forschungsarbeiten durchzuführen. Seit 1963 stehen beide Institute unter der Leitung von Prof. Dr. phil. Dipl.-Ing. Günther Glaser. Die enge Verbindung von Universitätsinstitut und Forschungsinstitut hat sich zur gegenseitigen Befruchtung von wissenschaftlicher Forschung und praktischer Anwendung in der Technik als günstig erwiesen. Dabei obliegt dem Hochschulinstitut unter dem Grundsatz der Freiheit von Lehre und Forschung die Ausbildung eines Nachwuchses und die Grundlagenforschung auf dem weiten und wichtigen Gebiet der Chronometrie, Feinmechanik, Mikrotechnik und Elektromechanik. Dem Forschungsinstitut obliegt die Durchführung von industrieller Zweckforschung, Gemeinschaftsforschung, Auftragsforschung sowie einer Information und Beratung auf dem Gebiet der Uhrentechnik und Feingerätetechnik. Die Uhr ist über 5000 Jahre alt und hat seither eine wichtige Aufgabe im menschlichen Leben. Während bis zum Mittelalter die Sonnenuhren zur Zeitmessung verwendet wurden, begann mit Galilei, Huygens, Hooke die Technik der mechanischen Uhren mit Pendel und Unruh. Sie brachte viele Erkenntnisse auf dem Gebiet der Physik, Metallkunde, feinmechanische Technologie. Die Uhrentechnik hat inzwischen gewaltige Wandlungen erfahren, insbesondere durch die Elektronik und Kunststofftechnik. Mit dem Transistor, dem piezoelektrischen Schwingquarz und der Atomuhr brach eine neue Ära der Chronometrie an mit einer gewaltigen Ausdehnung der Aufgaben im technischen und wirtschaftlichen Bereich. Die Uhr ist nicht nur Symbol der Zeit - simplex sigillum veri - sondern auch Beispiel für eine interdisziplinäre Wissenschaft der Technik und Kunst. Sie zu pflegen und dem technischen Fortschritt zu dienen ist die Aufgabe beider Institute.