Abstract:Sn-2.8Ag0.5CuX modified hypoeutectic solder was prepared by a new method. The processing properties of the liquid solder were studied. The results show that atomic-doping can significantly improve the oxidation resistance, wettability and overflowing ability of melting solder. The hypoeutectic component can reduce the solder cost and extend the stability of the liquid solder in the using process. In the air atmosphere at 265 ℃, the formation rate of oxide slag on liquid solder surface is only 0.36 mg/cm2·min. When using RMA-flux, the wetting time t0 is 0.82 s, wetting force F3 is 0.75 mN, and the rate of spread is about 78% for the solder on copper.