Crystal plasticity finite element simulation of TSV microstructure under thermal and vibration loading

The reliability of through-silicon-via (TSV) microstructures for advanced packaging is crucial. Few studies address their micro-mechanical behavior under thermal cycling, vibration, and thermal-vibration coupled loading. This study uses crystal plasticity finite element method (CPFEM) to investigate plastic deformation in TSVs. Plastic work (W_p) is used as a fatigue indicator parameter (FIP) for crack initiation prediction. CPFEM simulations show thermo-mechanical coupling causes the highest W_p amplitude, reducing fatigue life in the low-cycle fatigue (LCF) regime. Vibration loading mainly leads to high-cycle fatigue (HCF) or very high-cycle fatigue (VHCF). Crack initiation patterns vary: thermal cycling and thermo-mechanical coupling cause multi-site nucleation in TSV-Cu and at interfaces, while vibration loading results in single-point initiation at interfaces. Microstructural analysis reveals thermal cycling activates slip systems at quadruple-junction grain boundaries (GBs), with stress concentrations between clustered soft grains surrounded by hard phases. Thermo-mechanical coupling initiates cracks at trident GBs due to hard grain extrusion from yielding soft phases. Interface crack locations under hybrid loading relate to the distribution of the hardest grain. These results highlight the importance of loading type and microstructure in TSV degradation, emphasizing the need for grain boundary engineering and dimensional optimization to mitigate thermo-mechanical fatigue.