Effects of in addition on solidus and liquidus temperatures, microhardness, and wettability of Sn-0.3Ag-0.7Cu solder alloy

This research was aimed to study effects of indium (In) addition on solidus and liquidus temperatures, wetting time, wetting force, and microhardness of Sn-0.3Ag-0.7Cu lead-free solder alloy. It was found that In had a strong influence on these properties of Sn-0.3Ag-0.7Cu. Solidus and liquidus temperatures of the solder alloys was lowered as the In content was increased. However, In addition increased the melting range between solidus and liquidus temperatures. Wetting time of the solder alloy was reduced by the addition of In while the wetting force was increased with the increase of In content. Microhardness of Sn-0.3Ag-0.7Cu was increased by adding In into the solder alloy. With the addition of In, the Sn-rich phase was smaller in size, and the intermetallic compounds were more uniformly distributed.