M. Bagetti Jeronimo, J. Schindele, H. Straub, P. J. Gromala, B. Wunderle, and A. Zimmermann, “On the influence of lid materials for flip-chip ball grid array package applications,”
Microelectronics Reliability, vol. 140, p. 114869, 2023, doi:
https://doi.org/10.1016/j.microrel.2022.114869.
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.BibTeX
M. Bagetti Jeronimo, H. Straub, M. Hager, and A. Zimmermann, “Material Property Variability of Composites in Thermo-Mechanical Studies Involving Virtual Design of Experiments,”
IEEE Transactions on Components, Packaging and Manufacturing Technology, vol. 12, Art. no. 5, May 2022, doi:
10.1109/TCPMT.2022.3163460.
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.BibTeX
