Prediction of Activity of Au-Sn-Based Lead-Free Solder Using Modified Molecular Interaction Volume Model

Controlling thermodynamic properties is critical for the rational design and development of advanced lead-free solders, especially in high-temperature applications. Au–Sn-based alloys have emerged as promising candidates for high-performance electronic packaging, yet reliable thermodynamic descriptions of their multicomponent systems remain limited. The Modified Molecular Interaction Volume Model (M-MIVM) provides a effective approach for characterizing strongly asymmetric liquid alloys that are typical in Au–Sn-based systems. This work focuses on the thermodynamic modeling of Au–Sn-containing ternary and quaternary solder systems within a physically consistent and computationally efficient framework. The study aims to support the database development, composition design, and optimization of next-generation high-temperature lead-free solders.