Simon Petillon

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’ 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

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

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

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

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

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.

Zusammenfassung

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.