Investigation of the Microstructure, Thermal Properties, and Mechanical Properties of Sn-Bi-Ag and Sn-Bi-Ag-Si Low Temperature Lead-Free Solder Alloys

Abstract

In this study, we investigated the microstructure, mechanical properties, and thermal performance of Sn-xBi-1Ag (x = 35, 37, 45, and 47 wt.%) solders, with a particular focus on the effect of adding trace Si atoms. The impact of different Ag concentrations on the properties of Sn-xBi-Ag-0.5Si solders was also studied. The results indicated that as the amount of Bi added to Sn-xBi-1Ag solder alloys increased, the tensile strength, microhardness, melting temperature, and melting range decreased somewhat, but the wettability improved. The Cu6Sn5 layer between the soldering alloy and the Cu substrate became thinner upon increasing the Bi content. Adding microcrystalline Si atoms to the Sn-Bi-1Ag alloy improved the tensile strength and microhardness, but the melting point and melting range were not significantly changed. The wettability was optimized, and the diffusion layer formed with the Cu matrix was significantly thinner. By increasing the Ag content in the Sn-Bi-(1,3)Ag-0.5Si alloy, the tensile strength of the alloy was continuously strengthened, while the hardness decreased slightly and the melting point and melting range increased slightly. The wettability was greatly improved, and the Cu6Sn5 layer became thinner.

Evaluation of the microstructure, thermal, and mechanical characteristics of Sn-9Zn reinforced with Ni and ZrO2 nanoparticles via vacuum melting process

“…The fabrication of lead-free solders by the vacuum melting process is now widely used to improve the wetting characteristics and mechanical properties of lead-free solders. The vacuum melting process is a type of casting method used to fabricate Sn lead-free solder alloys where materials are melted under the protection of vacuum or other gases (hydrogen, argon, etc) in vacuum melting, which allows for precise control of the alloy composition and ensures a high degree of purity [31,32]. There is not enough study focused especially on the tensile properties of Sn-Zn based solders under elevated temperatures and strain-rate conditions.…”