Investigation of Effects of Porosity and Coarsening on Thermal and Mechanical Properties of Sintered Silver Die Attachment

Sintering of nano silver particles has been proven to be an effective technique for achieving the high-performance reliable interconnects required for microelectronics packaging of wide bandgap semiconductors. However, the porous structure of sintered silver induces the porosity and morphology dependencies of the properties of the interconnects. Capturing the dynamic microstructure evolution and coarsening of sintered silver interconnects during service is still challenging for experimental studies. This study develops a phase field model to simulate the microstructure of porous sintered silver and its dynamic evolution under thermal aging. Then, the porous structure of sintered silver is imported into the finite element model to analyze the changes in the thermal and mechanical properties of the sintered silver. It is found that as the porosity increases, the thermal conductivity and yield strength gradually decrease, which is in good agreement with the experimental studies. With increasing aging time, except for the sintered specimen with a porosity of 60%, the thermal conductivity of the other porous sintered silver increases slightly; the elastic properties mainly depend on the porosity of the sintered samples, and the yield strength decreases during aging due to the coarsening of pores.