An Experimental Investigation on the Properties of Two Novel Ternary Solder Alloys Sn–0.5Cu–3Bi and Sn–1Cu–1Ni Replacing Lead

Abstract

Lead is banned in the solder alloy composition, citing its inherent toxicity. The researchers were working towards the development of new lead free solder alloys which can replace the old Sn–Pb alloy. In the present paper two new solder alloys are introduced, Sn–0.5Cu–3Bi (96.5% Sn, 0.5% Cu, 3% Bi, all are % by wt) i.e. SCB305 and Sn–1Cu–1Ni (98% Sn–1% Cu–1% Ni) i.e. SCN110. The melting temperature of SCB305 and SCN110 are found to be 231.5 and 232.8°C, respectively. Therefore these two alloys can be used as solder material in electronic packages exposed to moderately higher temperature. Hardness of SCB305 and SCN110 are obtained as 19.8 and 16.1 HV. SCB305 and SCN110 have very good wetting characteristics with contact angle of 28.74° and good wetting characteristics with contact angle of 36.75°, respectively. Microstructure of SCB305 and SCN110 shows that Bi and Ni are evenly distributed in the Sn-matrix. The cost analysis revealed that SCB305 and SCN110 have cost of 23.05 and 20.65 $/kg. The properties of the new alloys were compared with that of SAC305 and SAC405. SCB305 and SCN110 are found to be perfect replacement of Sn–Pb alloy.