The effects of Ni addition on microstructure evolution and mechanical properties of solder joints undergoing solid-liquid electromigration

Abstract The effect of solid-liquid electromigration on Cu-xNi/Sn-3.0Ag-0.5Cu/Cu-xNi (x = 0, 1.5 and 5 wt%) joints bonded at 260 °C with electric density of 2.89 × 102 A/cm2 was investigated. The results showed that intermetallic compounds (IMCs) performed a non-interfacial growth in the Cu-5Ni/SAC305 system. The electron backscatter diffraction (EBSD) analysis revealed that the orientation of the Cu6Sn5 [1 0 0] direction parallelled to the direction of electric current, however, the addition of Ni could induce that the growth of (Cu,Ni)6Sn5 grain exhibited isotropy. Additionally, the additional Ni resulted in significant reduction in grain size and enhancement in the tensile strength of joints.