Effect of 4.0 mass % Cu addition on microstructure and mechanical properties of In-48Sn alloy

In-48Sn eutectic alloy has been considering a promising solder for some flexible and organic electronic devices because of their low heat resistance. However, In-48Sn alloy exhibits lower strength compared with other commercial alloys. In this study, we investigated the effects of 4.0 mass % Cu addition on melting temperature, microstructure, and mechanical properties of In-48Sn eutectic alloy. The results revealed that the melting temperature of the new In-Sn-4.0Cu alloy was closed to eutectic temperature (117 °C) caused by ternary reaction. Moreover, the η-Cu6(In, Sn)5 and τ-Cu2In3Sn intermetallic compounds (IMCs) were formed in the new In-Sn-4.0Cu alloy, which improved the tensile strength of new alloy compared to that of the eutectic In-48Sn alloy.