Equilibrium solidification of Sn-Ag-Sb thermal fatigue-resistant solder alloys

A survey of the liquidus surface and invariant reactions involving liquid has been made for solidification in the ternary Sn-Ag-Sb system. Differential thermal analysis and electron-beam microprobe analysis were used to measure liquidus temperatures and determine the composition of solid phases resulting from solidification. A liquidus projection and the composition of the phases coexisting at the two observed invariant reactions were determined. Ternary alloys based on the Sn-Ag-Sb system have been used as thermal fatigue-resistant solders where high heat loads must be dissipated. An analysis of the properties encountered from such solders is presented, based on the phase constitution resulting from the solidification behavior reported here. We wish to acknowledge the contribution of pure metals used in this research, as well as support and advice, by Cominco Electronic Materials of Spokane, Washington.