Interfacial reactions between liquid indium and Au-deposited substrates

The morphology and growth kinetics of intermetallic compounds formed during the soldering reactions of liquid indium on Au-deposited substrates in the temperature range of 225°C and 350°C have been investigated. The results show that two types of AuIn₂ intermetallic compounds make their appearance: the continuous-wavy-crystalline type, and the floating-island type. The growth of this intermetallic compound follows the parabolic law, which indicates that the growth is diffusion-controlled. The activation energy of the reaction calculated form the Arrhenius plot of growth reaction constants is 39.42 kJ/mol. Also, the wettability of liquid indium on the surface of the gold-deposited substrate is determined from contact angle measurements. Finally, a mechanism for the interpretation of the wetting behavior of the said Au/In system is proposed, which can be ascertained by SEM observations.