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. [doi:10.2320/jinstmet.J2016069]