Thermodynamic characterization of solder Au–Ga alloys

Abstract

Differential thermal analysis, Oelsen calorimetry as well as optical microscopy are used for thermodynamic characterization of Au–Ga solder alloys. Mechanical and electrical characteristic of the investigated alloys is done by measuring of hardness, micro hardness and electro conductivity. Obtained activities and activity coefficients at 873K are smaller than the unit, which means there is a negative deviation of the gallium activity from the Raoult law. Partial mixing and excess Gibbs's energy of gallium is negative for all investigated alloys and do not reach −1800 J/mol for the excess energy and −4400 J/mol for the mixing energy which indicates good miscibility regardless of the existence of an intermetallic compound (AuGa2) in the alloy that microstructural analysis is shown. The obtained good miscibility is excellent for solder characteristics of the investigated alloys.