Automotive High Power Module with Spacer on Die Bottom (Flip Chip) or Die Top (Wire Bond)

Abstract:
In order to maximize power density, dual side cool (DSC) configuration is one of the technologies EV/HEV industry is interested. In addition, DSC power modules can make traction inverter system design more flexible as compared to single side cooling (SSC) power modules. This solution is good fit for both SiC and IGBT power module. However, thermal-mechanical stress is always a challenge to make DSC power module work, unless thermal performance is sacrificed. Spacer is one of key components in DSC power module. Spacer composition and position would affect both thermal and thermal mechanical performance significantly. In this article, a design with spacer under the die bottom (flip chip concept) was proposed. The advantage of this design is the spacer is larger than die, this is different from the traditional spacer stacking structure, in which the spacer is on die top and spacers are smaller than power devices. In this paper actual DSC automotive power module spacer placement will be studied thru both simulation and practical power module assessment. Reliability assessment including thermal shock (TS) and power cycle testing (PCT) are also addressed.