Continuous strip casting, microstructure and properties of Au-Sn soldering alloy

This study tried to examine the suitability of strip casting processes such as PFC for soldering Au-Sn strips and to investigate changes in the microstructure and mechanical properties of the manufactured strips, following heat-treatment. Optimal production conditions were established for Au-20 %Sn strips and implemented to actually produce them. The inhomogeneous microstructure with indistinct phases that was present prior to heating was transformed into a homogeneous microstructure in which the continuous Au5Sn phase surrounded the ìm-sized AuSn phases. Tensile results showed that the as-cast strip exhibited zero plasticity and a tensile strength of 338.3 MPa. After heating, the figure dropped somewhat while the plastic strain improved to 1.6%. As for the enhanced plasticity in the heat-treated strip, the continuous pattern of the ductile Au5Sn that surrounds the brittle AuSn was assumed to have caused plastic strain to take place on the boundaries of two phases, therefore resulting in the initiation and propagation of cracks.