Improvement of Bonding Strength for Ag Sinter Joining Direct on Al Heatsink in SiC Power Module

Ag sinter paste for SiC die to AMB (Active Metal Brazing) substrate bonding have been used in the electric vehicle. To further meet the high temperature operation requirement, a bonding material with high thermal conductivity for AMB substrate to Al (aluminum) heatsink is also necessary to replace the TIM (Thermal Interface Material). In this study, we used the Ag sinter paste to direct bonding to Al alloy substrate in a low temperature low pressure sintering condition. In addition, to improve the bonding strength for the Ag sinter paste joint to Al substrate, Al surface treatment process including surface grinding, chemical solvent treatment (Surface corrosion method) and blasting treatment were proposed and investigated. The results show that the initial shear strength of Ag sinter paste direct to Al substrate was decreased for the surface grinding and chemical solvent treatment but can be improved by treating the Al surface with a blasting process. For the blasting treatment, the shear strength of joint structure was 41.4 MPa, which was improved and larger than that without surface treatment of 35.9 MPa.