Kinetic Evolution and Phase Transformation of Ni/In and Cu/In Intermetallics

Abstract

This study examines the kinetics and phase transformation of intermetallic compounds (IMCs) in Ni/In and Cu/In metallurgical systems under solid-state aging conditions. A non-destructive in-situ resistance measurement technique was utilized to continuously monitor IMC growth, overcoming the limitations of conventional SEM-based analysis. Findings indicate that the Ni/In system forms Ni3In7, following a reaction-controlled mechanism, with an activation energy of 108±30 kJ/mol. In contrast, the Cu/In system undergoes a two-phase transformation, where CuIn2 transitions into Cu11In9 via a peritectoid reaction at 107.5°C. The transformation mechanism progresses from reaction-diffusion mixed controlled regime (n≈0.73 at 110°C to diffusion-controlled (n≈0.45−0.62 at 120-140°C. At 150∘C(n≈0.19), we proposed that the transformation mechanism might have transitioned towards grain-boundary diffusion, though further validation is required. The activation energy for CuIn2→Cu11In9(196±82 kJ/mol) indicates a significantly higher energy barrier for transformation. These insights contribute to the advancement of low-temperature solid-state bonding techniques and the optimization of fine-pitch interconnects for next-generation electronic packaging applications.