Failure analysis and reliability evaluation of silver-sintered die attachment for high-temperature applications

This study demonstrates the reliability of SiC chip attachment sintered by nano-Ag paste during high temperature storage (HTS) tests in air at 350 °C, which was twice as high as the maximum junction temperature in service of the Si chip. The failure mechanisms of die attachment at high temperatures were diffusion and oxidation. The residual organics in the Ag paste was enough to provide the oxygen to form the continuous NiO layer at the bondline/SiC chip interface, and the oxide growth obeyed a parabolic rate law. Based on the microstructural evaluation and interfacial diffusion behavior of die attachment during HTS, the electroplated Ag layer was designed and applied on the ENIG finish as a diffusion barrier. The results showed that the die attached on the electroplated Ag substrate could support more than 800 h during HTS at 350 °C in air, which was doubled the reliability of the ENIG finished substrate.