Interfacial reaction at 250°C in the Sn/Ni-7wt.%V couple

Sn is the base element of all the promising electronic solders, and Ni-7wt.%V is the major diffusion barrier layer material of flip chip technology. Interfacial reactions in the Sn/Ni-7wt.%V couple at 250°C are examined in this study. The Ni₃Sn₄ phase is observed in the Sn matrix. Two phase layers, Sn-Ni-V ternary phase (T phase) and a mixture of the nano-crystalline V₂Sn₃ phase and Sn phase (T2 phase), are observed at the Sn/Ni-7wt.%V interface. The micro structures of T phase and T2 phase was analyzed by TEM, T phase has a dense structure and T2 phase has a loose structure. The loose structure of Sn-V phase can not only cause a harmful effect on mechanical properties, but also on electrical properties.