Abstract
In-Sn alloys are promising lead-free solders in low temperature soldering application. Cu is common used as under bump metallurgy (UBM) in electronic packaging. Interfacial reaction occurs at the In-Sn/Cu joints of electronic products during electric current stressing. Not only Joule heating but also electromigration effect contributes to intermetallic compounds (IMCs) growth. The poster exhibits the results of electromigration effect upon interfacial reactions in Sn-In/Cu joints. Same intermetallic phase, η-Cu6(Sn,In)5¬, formed at interface with or without electrifying. By the compositional analyses, the same intermetallic phase formed at both electric directions. However, it is significant morphological difference at interface stressed by upstream and down-stream of electric current. When electrons flew from In-Sn solder to Cu substrate, the reaction layer is flatter and similar to that without electrifying. On the other hand, when electrons flew in reversed direction, the IMCs grew along solder grain boundaries