Correlation between displacement rate and shear force in shear test of Sn–Pb and lead free solder joints

AbstractAn experimental investigation was combined with a non-linear finite element analysis using an elastic–viscoplastic constitutive model to study the effect of ball shear speed on the shear forces of ball grid array (BGA) solder joints. Two solder compositions were examined in the present work: Sn–37Pb and Sn–3·5Ag. Within the Sn–3·5Ag solder, Ag3Sn intermetallic compound particles were found. For both types of solder used, a Ni3Sn4 intermetallic compound layer was observed at the interface between the nickel plated layer and solder, while a gold layer appeared to have dissolved into the liquid solder leaving no observable gold at the interface. The shear force was observed to increase linearly with increasing shear speed and reached a maximum value at the highest shear speed in both the experimental and the computational results. All test specimens fractured in a ductile mode. The failure mechanisms are discussed in terms of von Mises stresses and plastic strain energy density distributions.