Effect of Indium on Microstructures and Mechanical Properties of Bismuth-Based High Temperature Solders

Abstract

With the rapid development of the electronic information industry, the reliability of electronic interconnection materials is crucial for the longevity of electronic components. Bi-based alloys have garnered significant attention as potential candidates for high-temperature solders. However, the inherent brittleness of Bi-based alloys has been a limiting factor in their application. In order to develop high-temperature Bi-based solders with superior performance, In element was chosen to modify the Bi-2Ag-0.5Cu alloy. Through the introduction of Ag₂In and BiIn phases, much finer microstructure of Bi-based alloy can be achieved (grain size decreases from 80 µm to 30 µm). Adding 2% Indium has led to notable improvements in ultimate tensile strength (σ_UTS) and fracture strain (ε_f), by 76.9% and 55.1% compared to Bi-2Ag-0.5Cu, respectively. Additionally, the melting point of the Bi-2Ag-0.5Cu-2In alloy is 534.3 K, meeting the specified requirements for a high-temperature solder.