Published online by Cambridge University Press: 21 February 2011
A 200°C fluxless process is developed to produce In-Cu joints. The fluxless feature is achieved by the prevention of indium oxidation during the solder fabrication and the bonding process. Indium and copper are deposited on an object in high vacuum to inhibit indium oxidation. Copper interacts with indium to form CuIn compound that further protects the inner indium from oxidation. For a specific design, the resulting joints consist of mainly CuIn intermetallic grains surrounded by a small amount of pure indium as revealed by SEM with EDX. Scanning acoustic microscope examination indicates that the joints are nearly void-free. This technology enables versatile control of the alloy composition, thus leading to several remelting temperatures and various physical properties.