Abstract: The effect of In addition (0.5-2.0wt.%) on thermal property, microstructure, wettability and interfacial reactions of Sn–8Zn–3Bi solder was investigated. Results showed that In addition lowered both solidus and liquidus temperatures of the solder with wettabilty significantly improved. The solidus temperature of Sn–8Zn–3Bi–1.5In was 185.7 °C, which is only 3 °C higher than that of the conventional Sn–37Pb solder (i.e. 183 °C). With the increase of In content, Zn-rich precipitates were smaller in size and distributed more uniformly. The intermetallic compounds (IMCs) formed between the solder and Cu substrate was identified as Cu–Zn with a scallop layer adjacent to the solder and a flat layer to the substrate. Addition of In slightly influenced the thickness of the IMCs. Therefore, the new Sn–Zn–Bi–In solder has great potential to replace the Sn–Pb solders as low-temperature lead-free solder in electronic assemblies.
Authors: Jian-Chun Liu, Xin-Hua Gao, Zhi-Jun Yue, Hai-Yan Zhang, Gong Zhang, and Katsuaki Suganuma
Keywords: Lead-free solder, In, Thermal pro perty, Wettability, Intermetallic compounds