Mechanical characterization of board-level 63Sn37Pb and lead-free solder sphere attachment on Cu-pad/Ni/Au surface finish substrate

The trends of miniaturization of the electronic products make the solder joint reliability become important. Solder joint reliability is closely related to the interfacial reaction. The increasing thickness of the brittle IMC (intermetallic compound) layer will degrade the joint integrity. Considering the IMC growth mechanism, shear test and failure mode analysis are used to completely understand the behavior of solder materials. Based on IMC experiment results, activation energy and diffusion coefficients of 63Sn37Pb, Sn3.5Ag and Sn4Ag0.5Cu were obtained, and the models of IMC growth mechanism at the interface between pad finish and the solder materials also have been established. Based on shear test and failure analysis, the variations of shear strength and failure mode transition of three different solder alloys are also discussed.