Yu-Chun Li¹, Ching-Hsun Chang¹, Hsien-Ming Hsiao², Satoshi Ikubo³, Yee-Wen Yen⁴; ¹Department of Materials Science and Engineering, National Taiwan University of Science and Technology, ²Institute of Nuclear Energy Research, ³Graduate School of Life Science and Systems Engineering, Kyushu Institute of Technology, ⁴National Taiwan University of Science and Technology

Interfacial reactions between lead-free solders, such as Sn, Sn-3.0Ag-0.5Cu and Sn-9Zn alloys and Cu-2.0% wt. Be (Alloy 25) by using liquid/solid couple technique were investigated. The result shows only the scallop-shaped (Cu, Be)6Sn5 phase was formed in the Sn/Alloy 25 couple reacted at 240°C for 0.5-2 h. When reaction times were increased to 4 h or reaction temperature at 255 to 270 °C, the (Cu, Be)3Sn phase was observed at interface. In Sn-3.0Ag-0.5Cu/Alloy 25 couple, the results are similar to those in the Sn/Alloy 25 couples. Only the scallop-shaped (Cu, Be, Ag)6Sn5 phase is formed at the interface. As the reaction time and temperature were increased, both the (Cu, Be, Ag)6Sn5 and (Cu, Be, Ag)3Sn phase were formed. The (Cu, Sn)Zn5 and (Cu, Sn)5Zn8 phases were observed in the Sn-9Zn/Alloy 25 couple. The thickness of intermetallic compounds in couples obeyed parabolic law and the IMC growth mechanism is diffusion control.