Intermetallic formation and characterization of Sn-Cu-Mn-Ag lead-free soldering alloys

Abstract

Two lead-free soldering alloys, namely 87Sn-7Cu-3Mn3Ag and 87.5Sn-7.5 Cu-2.5 Mn-2.5 Ag, were prepared and the effect of Mn addition to Sn-Cu-Ag alloys was studied. The alloy was characterized using XRD, DSC, and metallurgical microscopy. Hardness of the former alloy exceeded that of the latter, due to higher intermetallic formation, according to XRD studies. The DSC curves for both alloys have melting points of 219.4 and 219.7°C, with a range of melting close to 10 °C. The microstructure of both alloys contains Cu6Sn5, Ag3Sn, and MnSn2 present in dendritic Sn-rich solid solution.