Effect of in addition on the reaction and mechanical properties in Sn-Ag-Cu-In solder alloy

This study investigated the reaction and mechanical properties of a In added quaternary composition solder alloy having low Ag content, i.e. Sn-xAg-0.5Cu-yIn to replace the Sn-3.0Ag-0.5Cu composition used widely as a representative Pb-free solder alloy. We found that the In addition of small amount did significantly improve a wettability of the solder at the reflow temperature of 230~240degC. Moreover, the addition did also improve outstandingly the elongation of the solder alloy, thereby increasing the toughness of the alloy. With these results, it was found that if the added amount of In and Ag are optimized, the Sn-Ag-Cu-In quaternary alloy will be a strong candidate for the replacement of Sn-3.0Ag-0.5Cu composition.