Effects of Ni Additions on the Growth of CuSn in High-Lead Solders.

In reactions between solders and Cu, additions of minor alloying elements, such as Fe, Co or Ni, to solders often reduce the CuSn growth rate. Nevertheless, the mechanism for this effect remains unresolved. To provide more experimental observations that are essential for uncovering this mechanism, growth of CuSn in the reaction between Cu and high-lead solders with or without Ni additions has been studied. The solders used for this study were 10Sn-90Pb and 5Sn-95Pb doped with 0 wt.%, 0.03 wt.%, 0.06 wt.%, 0.1 wt.% or 0.2 wt.% Ni. Reaction conditions included one reflow at 350°C for 2 min and solid-state aging at 160°C for up to 2000 h. The effect of Ni on the growth of CuSn is discussed in detail based on the experimental results. [ABSTRACT FROM AUTHOR]