Effect of Cu and Ni addition on high temperature deformation behavior in Sn-Cu-Ni solder alloys

In recent years, it has become necessary to develop lead substitutes, such as lead-free solder alloys, because of increased environmental concerns regarding the use of leaded materials. In addition, electronic components that use lead-free solder alloys will need to be smaller and usable at higher operating temperatures in next-generation semiconductor devices. Therefore, lead-free solder alloys must be made more reliable. In this work, tin-copper-nickel( Sn-Cu-Ni) solder alloys, Sn-Cu solder alloys, and Sn-Ni solder alloys, as well as 99.96 mass% pure Sn, were subjected to tensile testing. The results showed the effects of adding Cu and Ni to Sn on the high-temperature deformation behavior of the Sn-Cu-Ni solder alloys. For each alloy and Sn, the stress exponent was estimated to be <5. This result indicated that, in each sample, the high-temperature deformation was controlled by dislocation creep. Furthermore, the creep activation energy was dependent on stress, and was affected to the greatest extent when adding Cu.