Geometry Optimization for Increasing Fatigue Life of Pressing Packaged IGBT with SiC Chips and Silver Sintering Layers

A novel SiC IGBT module packaging structure is proposed. Pressing packaging with silver sintering is adopted. The thermal analysis is made with FEM. A maximum temperature of 137°C is obtained when the module is working, which leads to significant fatigue problem. The minimum fatigue life of the fundamental model is 106, and it occurs in the upper silver layer nearby the SiC. Five improved models with different silver layer edge geometry are analyzed. It turns out that the best geometry optimization in this study can lead to a fatigue life of 141, that is, 33% higher than the fundamental model. This shows that a very subtle change in the geometry of the silver layer edge can lead to significant improvement of the fatigue life of the module. This result can provide useful reference for the design the third generation IGBT device.