Interfacial reaction between liquid Sn-20In-2.8Ag solder and Ag substrate

The morphology and growth kinetics of the intermetallic compound formed during the reaction between liquid Sn-20In-2.8Ag solder and Ag substrate are studied in the temperature range 225–325 °C. The results indicate that the intermetallic compound Ag (In, Sn) of scallop shape appears at the interface. The intermetallic thickness versus reaction time shows a parabolic relation, indicating that the growth of this intermetallic is diffusion-controlled. The activation energy calculated from the Arrhenius plot of the intermetallic growth rate is 41.6 kJ/mol. By marking the original interface with a Ta thin film, the dissolution of Ag into solder and the growth mechanism of the intermetallic compound have been clarified.