Sintered Silver Die Degradation Evaluation by Nine Point Bending Test Technique

This paper proposes the nine-point bending test technique for providing out-of-plane deformation with a sintered silver (s-Ag) die attach element for power modules to understand the s-Ag degradation mechanism during thermal shocked test (TST). By comparing NBT with TST, the s-Ag degradation is clarified from the aspect of mechanical and thermal stress. From the scanning acoustic tomography (SAT) image analysis, mean degradation rate was similar between TST and NBT up to 1000 cycles. That was mechanical stress played a significant role for determining the s-Ag die degradation during TST. The deviation value of TST, however, showed 5 times higher than the value in TST. From the cross section scanning electron microscopy image after 1000 cycles, cracking and s-Ag aging coexisted only in TST, leading to destabilize the s-Ag die part degradation.