Development of Pb-free nanocomposite solder alloys

Abstract

As an alternative to conventional Pb-containing solder material, Sn–Ag–Cu (SAC) based alloys are at the forefront despite limitations associated with relatively poor strength and coarsening of grains/intermetallic compounds (IMCs) during aging/reflow. Accordingly, this study examines the improvement of properties of SAC alloys by incorporating nanoparticles in it. Two different types of nanoparticles were added in monolithic SAC alloy: (1) Al₂O₃ or (2) Fe and their effect on microstructure and thermal properties were investigated. Addition of Fe nanoparticles leads to the formation of FeSn₂ IMCs alongside Ag₃Sn and Cu₆Sn₅ from monolithic SAC alloy. Addition of Al₂O₃ nano-particles do not contribute to phase formation, however, remains dispersed along primary β-Sn grain boundaries and act as a grain refiner. As the addition of either Fe or Al₂O₃ nano-particles do not make any significant effect on thermal behavior, these reinforced nanocomposites are foreseen to provide better mechanical characteristics with respect to conventional monolithic SAC solder alloys