| The motivation for this study is to improve the reliability of lead-free solder joints in electrical systems while removing lead. Solder microstructures under service conditions at high homologous temperatures tend to be highly unstable, resulting in failure of solder joints. This is caused by enhanced microstructural coarsening resulting from thermally-induced or mechanical stress. To improve the reliability of solder joints as well as to eliminate lead, lead-free in-situ composite solders based on eutectic Sn/Ag (96.5Sn/3.5Ag), which is a potential candidate for replacing leaded solders, were developed. A similar composite approach also was used with the eutectic Sn/Pb matrix for comparison. The creep behavior of unaged and aged composite solder joints was improved by a factor of 100-1000 as a consequence of the composite phase. Although the creep resistance of aged joints were degraded, composite solders still exhibited better creep behavior as compared to the corresponding non-composite ones. |
