The effect of indium microalloying on lead-free solders: A review

The restriction of using toxic and harmful Sn-Pb solders has led to the rapid development of lead-free solders in recent decades. This research on the effect of indium (In) microalloying on lead-free solders is of significant importance, offering a potential breakthrough in the field. Microalloying, a method to regulate the performance of the solder, involves adding alloying elements to make ternary, quaternary, and even quintuple alloy solder. With the development of semiconductor processes and packaging technology advances, lead-free solder at low temperatures has become an inevitable trend. In, which can be used as a microalloying component, has attracted attention because it is a low melting point metal with an atomic radius close to that of Sn. This paper reviews the effect of In on the organization, wettability, and thermal/mechanical properties of lead-free solders and their reliability in recent years. It also discusses the predictive role of first principles in micro-alloy doping and reviews the effect of first-principles calculations of In on intermetallic compound (IMC) properties.