Effect of Ni addition on the formation and growth of intermetallic compound at eutectic SnBi/Cu interface

摘要

The reactions between Cu and the eutectic SnBi (Sn58wt.%Bi) solder alloy with and without lwt.%Ni addition were investigated in this paper. After as-reflowed process, the IMCs formed in the Sn58wt.%Bi/Cu and Sn58wt.%Bilwt.%Ni/Cu joints were Cu_6Sn_5 and (CuNi)_6Sn_5, respectively. During aging process, the thickness of the IMC layers formed at each solder/Cu joint increased, and a new layer Cu_3Sn formed adjacent to the Cu substrate. It was found that lwt.%Ni addition in Sn58wt.%Bi solder alloy could slightly enhance the growth rate of the total IMC layer, but effectively reduce the growth rate of Cu_3Sn layer during aging process. The growth behavior of IMC layer for each joint followed the diffusion-controlled mechanism during aging.