The coupling effect of size effect and Krikendall voids on the fracture features of Ni/Sn3.0Ag0.5Cu/Cu joint

In this study, the formation mechanisms of Kirkendall voids in Sn3Ag0.5Cu/Cu and Ni/Sn3Ag0.5Cu/Cu joints were investigation, and the coupling effect of joint size and Kirkendall voids on the fracture features of Ni/SnAgCu/Cu joints were also studied. It was found that the size effect had a significant influence on the formation of Kirkendall voids at Cu side in Sn3Ag0.5Cu/Cu and Ni/Sn3Ag0.5Cu/Cu joint, the ratio of Kirkendall voids to the total area of Cu 3 Sn layer increased with solder volume irrespective of the structure of joint. The coupling effect of Ni and Cu inhibited the growth of Cu 3 Sn significantly and increased the ratio of Kirkendall voids to the total area of Cu 3 Sn layer. However, the Kirkendall effect seems to have no obvious influence on the fracture features of Ni/ Sn3Ag0.5Cu /Cu joints compared with Cu/Sn3Ag0.5Cu/Cu joint by using lap-shear test method.