Effect of Al on the microstructure and properties of Sn–0.7Cu solder alloy

Effect of Al on the microstructure and mechanical properties were investigated. The results showed that Al could depress the formation of eutectic phase in Sn–Cu–Al solder alloy. The intermetallic compounds of Sn–0.7Cu–0.03Al were refined compared with that of Sn–0.7Cu–0.015Al. Segregated CuAl intermetallic compound was observed in Sn–0.7Cu–0.15Al and Sn–0.7Cu–0.5Al solder alloy. Sn-whisker was observed on the polished surface of Sn–0.7Cu–0.15Al and Sn–0.7Cu–0.5Al. The ultimate tensile strength of Sn–0.7Cu–0.03Al and Sn–0.7Cu–0.5Al was found to be higher than that of Sn–0.7Cu–xAl (x = 0, 0.015 and 0.15). The elongation of Sn–0.7Cu–0.015Al was the highest. The creep performance of Sn–0.7Cu–0.03Al and Sn–0.7Cu–0.5Al was similar and higher than that of Sn–0.7Cu and Sn–0.7Cu–0.15Al.