Development of lead-free Sn-0.7Cu/Al2O3 nanocomposite solders with superior strength

Sn-0.7Cu is a low cost lead-free solder alloy that is targeted to replace the eutectic Sn-Pb solder. The main limitation of this alloy is its poor strength characteristics. Accordingly, this study aims at improving the mechanical properties of Sn-0.7Cu using Al2O3 particulates in the nanolength scale. The development of nanocomposite solders was accomplished using the powder metallurgy technique incorporating microwave sintering. Results of characterization studies conducted on the extruded samples revealed the presence of equiaxed grains, Cu6Sn5 phase and pores. The mechanical properties (microhardness, 0.2% YS and UTS) increase with the increasing presence of reinforcement with the best tensile strength realized for the composite containing 1.5% alumina that far exceeds the strength of the eutectic Sn-Pb solder.