Thermal fatigue behaviors of SiC power module by Ag sinter joining under harsh thermal shock test

The excellent properties of SiC bring new challenges for the device packaging. In this study, the bonding strength, fracture behaviors and microstructural evolution of micron-porous Ag joint were elevated during thermal cycling (-50 ºC-250 ºC) in SiC/DBC (direct bonding copper) die attachment structure for different time. During harsh thermal shock test, the strength of sintered joint deceased gradually with the increase of cycling number, and the value just was half of the value of as-sintered after 1000 cycles. Coarsening of Ag grains was observed in micron-porous joint with the structure inhomogeneity and defects increasing, which were the reasons of the strength decease. In addition, it was also found that the fracture behavior of sintered joints was changed from ductile deformation of Ag grain to brittle fracture of crack propagation after 1000 cycles. This study will add the understanding in the mechanical properties of Ag sinter joining and its applications at high temperature.