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.