This study focuses on the characterization of the Ni/In/Cu microstructure. Ni and Cu are chosen because they are common materials in electronic devices, and In is one of the elements in commercial solders. The benefit of this joining process is the production of a bond at a low temperature. However, knowledge of the behaviors of the Ni/In/Cu ternary system at low temperatures is lacking due to issues with sample preparation. In this study, reactions at low temperatures and in the presence of a thin In layer are discussed. The interfacial reactions of Ni/In/Cu are systematically investigated to provide information about low-temperature reactions that involve the interdiffusion of a thin In layer. The results of this study show that (Cu,Ni)In2 is a stable phase below 100 °C and (Cu,Ni)11In9 is a dominant phase between 120 °C and 180 °C. In addition, a thin layer of (Ni,Cu)3In7 forms near the Ni side. The sequential microstructural evolution, such as microvoid growth and phase transformations, are discussed in this study.
Journal of Materials Science: Materials in Electronics