The Effect of Porosity on Thermal Properties of Nano-Silver Solder for Electronic Packaging

Sintered nano-silver solder has the characteristics of high melting point and high thermal conductivity, which is widely used as a material for chip-substrate interconnection in SiC power devices. Since the sintered nano-silver solder contains a pore structure, it is of great significance to study the thermal conductivity of nano-silver with different porosity. In this paper, a method for establishing a finite element model of porous nano-silver was proposed, the thermal conductivity of nano-silver was predicted, and the relationship between different porosity and thermal conductivity was studied. The simulation results show that since the thermal conductivity of the position containing pores is almost zero, the heat flow of nano-silver is only transferred between silvers during the heat transfer process, and the temperature distribution becomes unstable due to the increase of porosity. The rate decreases rapidly with increasing internal porosity. Moreover, for the nano-silver structure with the same porosity, the thermal conductivity does not change with the distribution of pores.