| dc.description.abstract | This study investigates the interfacial reaction of 50In-50Bi/Cu and In/Cu. The interfacial reaction is classified into liquid-state reaction and solid-state reaction. The reaction evolution was analyzed by scanning electron microscopy to observe the microstructure, X-ray diffraction, and electron probe X-ray microanalysis to characterize the intermetallic compounds (IMCs) at the interface. Therefore, the growth behavior of IMCs is discussed through kinetics. To know the influence of solder joints during thermal processes, shear tests were carried out. In a 50In-50Bi/Cu system, an interfacial IMC, Cu11In9, was formed at 120 °C. In addition, the IMC thickness increased with reflow time. The interfacial IMC separated into two layers during 30-minutes reflow. The upper part was Cu11(In,Bi)9 which contained more Bi than the lower part of IMC. The growth mechanism of Cu11In9 in this system at 120 °C was diffusion-controlled by kinetics. In the In/Cu liquid state reaction, the interfacial IMCs are Cu11In9 and CuIn2, and the growth rate of Cu11In9 in the 50In-50Bi/Cu system was slow during 40 °C, 60 °C, and 70 °C aging processes. The thickness of the interfacial IMCs apparently increased when the aging temperature rose to 80 °C. As a result of the In/Cu solid-state reaction, CuIn2 existed as a low-temperature metastable phase under 50 °C. Moreover, CuIn2 tended to transform into Cu11In9 above 70 °C. For 50In-50Bi/Cu shear tests, the shear strength of solder joints increased with the aging time at various temperatures. In addition, the cases of brittle fracture decreased after aging. In conclusion, long-term aging could improve the mechanical properties of the 50In-50Bi/Cu system in this experiment. | en_US |