Among the lead-free solder materials,Sn-AgCu 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-AgCu 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.
