Effect of displacement rate on lap shear test of SAC solder ball joints

Lap-shear tests were combined with elastic-viscoplastic constitutive modeling to study the shear behavior of Sn3.8Ag0.7Cu (SAC) solder ball joints. In the shear rate range of 0.005mm/s to 0.7mm/s, the peak shear force was attained an optimal rate (labeled as v o ), around 0.3mm/s. On either side of v o , the shear fracture behavior was quite different. Cross-section examinations of the remaining solder joints after fracture showed that the fracture surface moved towards the solder/IMC interface with an increasing shear rate. Two shear modes were evident: below v o , a cohesive shear fracture controlled by the solder properties and above v o , solder/IMC interface controlled fracture.