Advanced SiC power module packaging technology direct on DBA substrate for high temperature applications: Ag sinter joining and encapsulation resin adhesion

SiC die attach bonding based on a micronsized Ag sinter paste direct on DBA (direct-bonded aluminum) substrate was developed, which achieve a high shear strength about 35 MPa at a low temperature of 200 °C without assisted pressure. Scanning Electron Microscope (SEM) and Transmission Electron Microscope (TEM) observation provided a trustworthy interface bonding mechanism, where self-generated Ag nanoparticles from the Ag paste during the sintering formed a dense layer which touched on the DBA substrate top surface. In addition, a thin Al oxide can be found at the top surface of DBA substrate, which was an amorphous structure with the thickness less than 10 nm. The selfgenerated Ag nanoparticles uniformly adhesion on the Al oxide layer and thus achieve a robust interface bonding. Shear strength still larger than 30 MPa after aging at 250 °C for 1000 h, indicating that this bonding structure have a good high temperature stability. The encapsulation polyimide resin for high temperature application was first time used to bonding with Al substrate. The average shear strength of pudding cup on Al substrate was evaluated as 20 MPa by a shear test.