Influence of Fe and Ho additions on Sn-3.0Ag-0.5Cu solder alloy: Microstructure, electrochemical and mechanical properties

In this work, the microstructure, electrochemical and mechanical properties of Sn-3.0Ag-0.5Cu solder alloy with Fe and Ho additions were studied. The results demonstrated that adding of Fe and Ho improved the microstructure of solder alloy and formed FeSn2 phase and Ho5Sn3 phase. Besides, the addition of Fe weakened the microhardness and tensile properties of the solder alloy, which was ascribed to a weak interface between FeSn2 and beta-Sn matrix. The microhardness and tensile properties of solder alloy were enhanced by adding Ho owing to the improvement of microstructure and the strengthening of the second phase. Electrochemical tests and atomic force microscopy (AFM) results showed that comparing to the base solder alloy, higher corrosion current densities and rougher surfaces after corrosion were found in the solder alloys with the Fe and Ho additions.