Investigation of the Mechanical Properties of Sn–58Bi/Sn–3Ag–0.5Cu Composite Solder

Abstract

A Sn–58Bi (SB)/Sn–3Ag–0.5Cu (SAC) composite solder was developed to overcome the challenges, e.g., the low ductility, deterioration of bonding properties and joint reliability, associated with SB eutectic solder and enhance its mechanical bonding properties. Specifically, four types of SB/SAC composite solder samples with different SB/SAC mixing ratios (100:0, 50:50, 20:80, and 0:100) were formulated. Two types of mechanical property investigations, i.e., ball shear and microhardness tests, were conducted to explore the influence of the SB/SAC mixing ratios on the mechanical properties of SB/SAC composite solder joints. The results indicated that the mechanical properties of the joint that containing both SB and SAC were superior to that with only SB or SAC. Furthermore, the mechanical properties of SB/SAC composite solder joint increased linearly with increasing SAC content. This improvement was attributable to the precipitation hardening and dispersion strengthening induced by the presence of fine intermetallic compounds and Bi-rich phase particles dispersed in the SB/SAC composite solder joint.

Fig. 4 Microstructures of the SB/SAC composite solder joints with different SB/SAC mixing ratios: (a) 100:0, (b) 50:50, (c) 20:80, and (d) 0:100.