The Anomalous Microstructural , Tensile and Aging Response of Thin Cast Sn 3 . 9 Ag 0 . 6 Cu Lead Free Solder

-In this study bulk and thin cast samples were produced with an identical Sn3.9Ag0.6Cu composition. The thin cast material exhibited a much finer as-quenched microstructure than the bulk material with the IMC phase restricted to a thin network. Both the bulk and thin cast materials continually softened during room temperature aging, while both materials initially softened and then subsequently hardened when aged at 120C and 180C. The thin cast material was in all cases significantly softer than the bulk material, and responded to aging as if it were bulk material aged at a higher temperature. These results have significant implications for the elevated temperature application of Sn3.9Ag0.6Cu.