Investigating the Effect of Temperature Gradients on Crack Propagation and Performance Degradation of SiC Power Modules with Sintered Silver Die Attach

Driven by the demands for higher efficiency, miniaturization, and thermal performance, the power density of wide-bandgap power semiconductor devices, particularly SiC-based modules, has been increasing. This trend leads to significant lateral temperature gradients across the chip surface, consequently exerting critical impacts on the thermo-mechanical response of the die attachment and threaten the long-term reliability of power modules. Despite its importance, the effects of thermal gradients on crack initiation and propagation in SiC power modules with sintered silver die attach remains insufficiently understood. In this study, a finite element model of a representative SiC power module incorporating a sintered silver die attach layer is developed. To accurately capture crack evolution under thermal stress, the finite element analysis is coupled with a phase field fracture model. Simulation results dynamically reveal that higher lateral temperature gradients significantly increase the von Mises stress and strain energy density within the sintered silver layer, thereby accelerating crack propagation and potentially leading to premature failure. These findings provide valuable insights into the degradation mechanisms of sintered die attach materials and offer guidance for improving the reliability of SiC power modules.