Rapid Transient Liquid Phase Sintering by Ag-In Solder Pastes for High-temperature Power Electronics

The transient liquid phase sintering (TLPS) can fabricate solder joints of a high-remelting point with a relatively low temperature and short joining time, which shows excellent application prospects in power electronics. In this work, different Ag/In mass ratios were used to prepare high temperature Ag-In solder joints successfully by TLPS. The effects of Ag/In ratio, peak temperature dwelling time and aging time on the interfacial microstructure, chemical composition and porosity of the solder joints were studied. It is found that these Ag-In solder joints were composed of three parts including small Ag2In particles, large AgIn2 particles and a pure Ag skeleton. Porosity is negatively correlated with the peak temperature dwelling time of TLPS and decreases with the increase of Ag content in Ag-In solder pastes. Besides, as the aging time increases, the porosity in the solder joints decreases along with a significant densification of Ag.