Creep corrosion cracking of Sn-3.0Ag and Sn-0.5Cu solder alloys in NaCl solution

The surface crack nucleation of Sn-3.0Ag and Sn-0.5Cu solder alloys has been examined by performing sustained tensile-loading tests in 0.9 mass% NaCl solution at room temperature. For Sn-3.0Ag alloy, many cracks nucleate and propagate on the side surface of the specimen, similarly to Sn-3.0Ag-0.5Cu alloy reported previously. For Sn-0.5Cu alloy, such cracks are not observed, and ordinary creep deformation occurs in the solution. The effect of sustained applied stress, i.e., creep, on the dissolution of ions is smaller for Sn-0.5Cu alloy than for Sn-3.0Ag alloy. The present results suggest that there are differences in the susceptibility to cracking under applied stress in a solution, i.e., creep corrosion cracking, among lead-free solder alloys.