Lifetime Evaluation of Nanoscale Silver Sintered Power Modules for Automotive Application Based on Experiments and Finite-Element Modeling

The thermomechanical behavior of power modules has been always an issue with regard to reliability improvement. Silver sintering technology is one of the few alternatives for die attachment, which could bring a longer operating lifetime. Finite-element modeling (FEM) is as critical as the experimental development for such a new technology. In this paper, we present a lifetime evaluation approach for power modules used in automotive applications due to thermal characterizations, thermal ageing, and thermomechanical FEM analyses. A lower coefficient of thermal expansion mismatch with the silver sintering technology as compared with soldering increases the thermomechanical resistance to thermal swings (about six times). The FEM analyses of the accumulation of the strain energy density help understand and locate the high-stress area in a silver-sintered power module. Finally, this paper leads us to estimate the operating lifetime of silver-sintered assemblies for a specific mission profile by considering the thermomechanical behavior.