Massive spalling in Pb-free solder on co-based surface finishes

This paper investigates massive spalling that occurs in the intermetallic compounds at the interfaces between Pb-free SAC 305 and Co-based surface finishes. The SAC 305 solders were reflowed on the Co-based substrates and aged at different conditions. The samples were cross-sectioned to study the interfacial morphology. The occurrence of massive spalling depends on the constituents of the substrates. Shear tests were performed on the samples to evaluate the influence of massive spalling on the mechanical strength of the joints. The results indicated that massive spalling did not deteriorate the joint strength.