Investigation of microstructure, corrosion and mechanical properties of iron and holmium modified Sn-3.0Ag0.5Cu solder alloy with ultrasonic treatment

Abstract

This research investigated the microstructure, corrosion behavior and mechanical properties of iron and holmium modified Sn-3.0Ag-0.5Cu solder alloy with ultrasonic treatment. The results demonstrated that the distribution of the phases in the ultrasonically treated solder alloys became homogeneous and the microstructure of ultrasonically treated solder alloys were more refined. The average grain size of ultrasonically treated solder alloys was reduced from 206.7 μm to 184.1 μm. A significant increase in the tensile strength from 38.75 MPa to 47.38 MPa was found in the ultrasonically treated solder alloys. The polarization curves results indicated that the solder alloys treated with ultrasound possessed lower corrosion current density and the results of atomic force microscopy suggested that roughness of corrosion products morphology was reduced. Furthermore, the electrochemical impedance spectroscopy (EIS) results indicated that the ultrasonically treated solder alloys had larger diameter of the semicircular loops and higher total impedance values.