Role of Ni impurities in solid-state diffusion of intermetallic compounds in the Sn-0.7Cu-10Bi-xNi/Ni interface reaction

Abstract

The interface reaction of Sn-0.7Cu-10Bi-xNi/Ni (SCB-xNi/Ni) samples in the aging process was investigated. The initial (Cu,Ni)6Sn5 phase existed in the SCB-0.05Ni alloy, and would aggregate to the top of the intermetallic compounds (IMCs) layer under the drive of adsorption force. As a diffusion barrier, the (Cu,Ni)6Sn5 could stop Ni diffusion to the solder and reduce the interface Ni concentration, so that the IMCs layer could be dissolved and become thinner. As a result, the growth of the IMCs layer was effectively inhibited, and atomic diffusion and growth evolution of IMCs in the interface reaction were changed with addition of 0.05 wt% Ni.