Interfacial Reaction Thermodynamics between Sn-Cu-Ag Solder and Ni Substrate

Interfacial reaction during wetting and spreading of Sn-Ag-Cu solder on Ni substrate is a key factor in order to improve the mechanical properties of the joints and the weld quality. Therefore, it’s important to focus on the thermodynamic and kinetic analysis of this interface reaction. In this paper, the sessile drop method was used to study the spreading contour evolution. The Kissinger method was used to calculate thermo-kinetic parameters of reactions between Sn-Ag-Cu solder and Ni substrate based on DTA data. The results show that Cu reduces activation energy and reaction rate of Sn-Ag-Cu/Ni system. (Cu, Ni)6Sn5 phase mainly constitute the interface reaction layer of Sn-Ag-Cu/Ni. As the temperature increases, partial (Cu, Ni)6Sn5 phase is substituted by Ni3Sn4 phase.