Mechanical strength and fracture mode transition of Sn-58Bi epoxy solder joints under high-speed shear test

摘要

The shear force and failure behaviors of the Sn-58Bi epoxy solder joints with various surface finishes under the high-speed shear test were investigated. The relationships between the shear speed, shear force, and fracture mode are elucidated in this study. The shear force of the Sn-58Bi solder joints increased with increasing shear speed, mainly due to the high strain-rate sensitivity of the solder alloys. Brittle interfacial fractures were more easily achieved at higher shear speed in the high-speed shear test. This result was discussed in terms of the relationship between the strain-rate of the solder alloy, the work-hardening effect, and the resulting stress concentration in the interfacial regions. The fracture mode changed from ductile solder fracture to brittle interfacial fracture with increasing shear speed. On the other hand, the different surface finish materials did not affect the shear force and fracture mode of the Sn-58Bi solder joints under highspeed shear loading.