Interfacial reactions and growth kinetics for intermetallic compound layer between In-48Sn solder and bare Cu substrate

The growth kinetics of intermetallic compound layer formed between In-48Sn solder and bare Cu substrate were investigated at temperatures between 70 and 100 °C for 0-60 days. In the solder joint between the In-48Sn solder and bare Cu substrate, the intermetallic compound layer was composed of two phases: Cu(In,Sn)2 adjacent to the solder and Cu6(In,Sn)5 which was the dominant phase. A quantitative analysis of the intermetallic compound layer thickness as a function of time and temperature was performed. Additionally, the thickness of these intermetallic compounds increased with increasing aging temperature and time. The layer growth of the intermetallic compound in the couple of the In-48Sn/Cu system satisfied a parabolic law in the given temperature range. As a whole, because the values of time exponent (n) is approximately equal to 0.5, the layer growth of the intermetallic compound was mainly controlled by a diffusion mechanism in the temperature range studied. The apparent activation energies calculated for the growth of the total of intermetallic compounds [Cu(In,Sn)2 + Cu6(In,Sn)5] and for Cu6(In,Sn)5 were 95.11 and 97.63 kJ/mol, respectively.