Abstract: Wettability of Sn-9Zn-X (Ag, Al, Ga)leadfree solder, with non-cleaning flux and ZnCl₂-NH₄Cl flux, was appraised by means of wetting balance method in air and N₂ atmospheres; the effect of different additive amount of Ag, Al, Ga on the wettability of Sn-9Zn-X solders was studied.The results indicate that the optimum additive amount of Ag, Al, Ga in Sn-9Zn solder is 0.3, 0.005-0.02 and 0.5 mass percent, respectively.Thewet-tability of Sn-9Zn-X can be obviously improved in N₂ atmospheres.It is also found that Sn-9Zn-X lead-free solders show preferable wettability with ZnCl₂-NH₄Cl flux, even better than that of Sn-3.5Ag-0.5Cu solder under the same condition, which may reveal the feasibility of improving the wettability of Sn-Zn series lead-free solders by developing suitable flux.