Effect of Er on microstructure and properties of Sn-3.0Ag-0.5Cu lead-free solder alloy

Trace rare earth element Er was added into Sn-3.0Ag-0.5Cu solder to investigate the effect of rare earth on the microstructure and mechanical properties of SnAgCu solder. The results show that, when Er content (mass fraction) is within 0.05%-0.50%, the Er has a slight effect on the resistivity and corrosion, and lowers the melting range. When Er content is 0.05%, the shear strength is the highest. When Er content is 0.10%, the spreading area is the biggest and the tensile strength is the highest. When Er content is 0.25%, the elongation is the highest. With the increase of Er content, the microstructure of the solder changes from fir-tree crystal to equiaxed crystal and is refined. And the suitable content of Er is within 0.05%-0.25%.