Evaluation of thermal conductivity for sintered silver considering aging effect with microstructure based model

Sintered silver is a very promising die-attach material which is hopeful to be adopted in the third generation of power electronics. Thermal conductivity is an important index to characterize the heat conduction capacity of sintered silver. In this paper, a numerical model to compute equivalent thermal conductivity of sintered silver is proposed and verified based on the method with microstructure characteristics modelling. Based on the computations, the variations of the equivalent thermal conductivity for sintered silver are presented where porosity effect and aging effect are taken into account. Comparisons of heat flux distributions and temperature distributions of sintered silver with different porosity ratios and aging time are also made. A theoretical model is proposed to evaluate the equivalent thermal conductivity of sintered silver, which agrees quite reasonably with existed experimental results. Based on the proposed model, a theoretical model to predict the equivalent thermal conductivity of sintered silver considering aging effect is also presented. The method given in this paper can be used to predict the equivalent thermal conductivity of sintered silver under different loading conditions considering aging effect.