The influence of sintering process on thermal properties of nano-silver paste

Nano-silver paste with low sintering temperature and high operation temperature was introduced to the application of bonding materials for GaN and SiC devices. Thermal properties are critical issues for die attach materials due to the heat dissipation requirements of high power devices. The influence of sintering process parameters for nano-silver paste on the thermal properties was investigated. The thermal conductivity of sintered nano-silver paste increased with the increase of sintering temperature and sintering time because of the dense structure due to high temperature and long sintering time. To improve the thermal property, Ag coated micro-SiC particles were used as an alternative to partly replace pure nano-Ag particles. The results demonstrate that the SiC particles can reduce the voids and improve the density of the sintered silver structure. Moreover, the addition of SiC particles can also contribute to the increase of thermal diffusivity. As a result, the thermal conductivity of sintered silver paste with 1.5 wt.% Ag coated SiC particles was two times as compared to that without SiC particles with the same Ag concentration.