Interfacial Reactions in the Sn-3.0 wt.%Ag-0.5 wt.% Cu (SAC)/Cu-Ni-Si-Mg Alloy (C7025) Couples

This study investigates the liquid-solid interface reactions of Cu-3.0 wt%Ni-0.65 wt%Si-0.15 wt%Mg (C7025) copper-nickel-silicon-magnesium alloy, widely utilized in the electronic assembly industry. Despite its prevalent use in lead frames, no scholarly exploration has delved into its interaction with lead-free solder. Three lead-free solder alloys, Sn, Sn-3.0wt. %Ag-0.5wt. %Cu, and Sn-0.7wt.%Cu, were examined at varying temperatures and reaction times. The results reveal distinct intermetallic phases, influenced by temperature and time. Notably, the presence of Ni atoms in C7025 inhibits Cu
3
Sn phase growth, affecting brittleness. The study emphasizes a linear correlation between intermetallic phase thickness and the square root of reaction time, attributing the mechanism to diffusion control. While C7025's application in lead frames exhibits certain limitations, this research contributes insights into its liquid-solid interface reactions with lead-free solder. Keywords: C7025 alloy, lead-free solder, liquid/solid interface reaction, lead frame material.