Effect of electroplated tin coating on properties of BAg50CuZn brazing filler metal

Tin was electroplated on BAg50 CuZn brazing alloy, and the surface morphology of tin coating was observed by scanning electron microscopy(SEM). The effect of tin coating on the melting temperature and wettability of brazing alloys was analyzed using differential scanning calorimetry(DSC) and wetting test furnace. The composition of brazing alloys was discussed after electroplating tin coating. The results show that the wettability of the brazing alloy was improved, the DSC endothermic peak shifted to the left, and the melting temperature of brazing alloys decreased with the addition of tin coating. When 4.8% tin coating was electroplated on brazing alloy, a smooth and uniform tin coating was obtained, and the maximum wetting area of brazing filler metal was 236 mm². The contents of Ag, Cu and Zn reduced in the brazing alloys after electroplated tin, the reduction amount of silver in brazing filler metal was lower than that of copper, but higher than that of zinc.