Effects of In nanoparticles on melting characteristics, microstructure, and shear strength of Sn58Bi solder

The melting characteristics, microstructure, and shear strength of Sn58Bi solder with varying amounts of In nanoparticles were investigated. The results show that the peak temperature of Sn58Bi solder can be significantly reduced by adding In nanoparticles. Compared to the Sn58Bi solder, the peak temperature of Sn58Bi–1.0In solder decreased from 144.2 to 141.5 °C. With the addition of In nanoparticles, the microstructure of Sn58Bi solder joints was refined, and the growth of intermetallic compound (IMC) layer at the interface was effectively inhibited. When the content of In nanoparticles reached 1.0 wt%, the thickness of IMC layer was reduced from initial values of 6.2 μm (upper end) and 6.9 μm (lower end) to 4.9 μm and 5.1 μm, respectively. In addition, shear test results indicate that the Sn58Bi–1.0In solder joints exhibit optimal mechanical performance, achieving an average shear strength of 41.2 MPa, which represents a 17.4% enhancement compared to the Sn58Bi solder joints.