Novel SACX Solders with Superior Drop Test Performance

Abstract

ABSTRACT A family of SACX alloys has been developed with significant improvement in drop test performance on NiAu surface finish. Dopants such as Mn, Bi, Ti, Ce, and to a less extent Y for SAC105 have been observed to show very positive effect when used alone or in combination, with Mn exhibiting the most profound effect. SAC+Mn outperformed not only SAC alloys, but also Sn63, thus completely altered the shaky position of SAC systems caused by fragility of solder joints. The melting and intermetallic formation properties are not affected by the dopants. Mn tends to migrate toward IMC and accumulate near IMC layer in the form of MnSn 2 particles. Thermal aging results in further improvement of drop test performance.