Effect of nano α-Fe₂O₃ additions on physical and mechanical properties of Sn–1.0Ag–0.7Cu–xFe₂O₃ low Ag lead-free solders

In this study, the α-Fe₂O₃ nanoparticles were successfully fabricated by chemical method. Smelting technique has been used to prepare the Sn–1.0Ag–0.7Cu–xFe₂O₃ composite solders, while the weight percent of α-Fe₂O₃ in the solders ranged from 0 to 1 wt%. The influences of α-Fe₂O₃ nanoparticles on microstructure, melting temperature, microhardness, and coefficient of thermal expansion (CTE) of the composite solders and on mechanical properties of the composite solders joints were investigated. The results indicate that added α-Fe₂O₃ nanoparticles can remarkably improve the Vickers microhardness of the composite solders and decrease the CTE of composite solders, while the melting temperature of the composite solders have no obvious change, compared to the original Sn–1.0Ag–0.7Cu solder. The shear strength and tensile strength of the solder joints will be increased firstly and then decreased with the increasing of α-Fe₂O₃ in the composite solders. And the Sn–1.0Ag–0.7Cu–0.4Fe₂O₃ solder joint possesses the best shear strength and tensile strength.