Among the lead-free solder materials, Sn–Ag–Cu alloys have many advantages, such as good wetting property, superior interfacial properties and high creep resistance. In this article, the organization and welding performance of Sn–Ag–Cu material were investigated. The surface morphology of the two alloys was observed by stereoscopic microscope and scanning electron microscope (SEM). Chemical constitution was examined by X-ray energy-dispersive spectroscopy (EDS). The mechanical properties of Sn–Ag–Cu solder were evaluated systematically compared with those of Sn–Cu solder. The results show that Sn–Ag–Cu solder based on different solder pads has different welding properties. The thickness of intermetallic compound (IMC) at the interface increases with aging time. For the gold-plated pads, there are a large number of IMC graphic, and in the welding interface, it can reduce the reliability of electrical connection. The Sn–Ag–Cu solder joints show a superior mechanical property over the traditional Sn–Cu solder. The number of dimples decreases and that of cavities increases for Sn–Cu0.7 alloy and the fracture surfaces of Sn–Ag3.0–Cu0.5 alloy have many small size dimples which are homogeneously distributed.
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This study was financially supported by the Chinese Universities Scientific Fund (No. 2013RC0402), the Science & Technology Planning Project of Jinan City, China (No. 201401056), the Natural Science Foundation of Shanxi Province, China (No. 2013011023-5), and the Taiyuan University of Science & Technology Doctoral Fund (No. 20122029).
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