CHARACTERISTICS OF Sn-Ag-Cu-In QUATERNARY SOLDER COMPOSITIONS AND RELIABILITY EVALUATION OF THE SOLDER JOINTS

摘要

This study proposes a quaternary (i.e. Sn-Ag-Cu-In) solder alloy to replace the conventional Pb-free solder alloy of Sn-3.0Ag-0.5Cu composition. For this purpose, the proportion of In and Ag - expensive elements among the ingredients added - is minimized and optimized. The composition suggested in this study, Sn-1.2Ag-0.5Cu-0.4In, has better wetting properties than Sn-3.0Ag-0.5Cu. Its mechanical properties and reactions to the under bump metallurgy (UBM) are improved, and hence it shows high reliability when used as a soldering material. Against this backdrop, this new Pb-free solder composition is expected to serve as a replacement for the Sn-3.0Ag-0.5Cu composition.