Effect of micro tin brush-electroplated coating on properties of AgCuZnSn brazing filler metals

Tin coating were brush electroplated on BAg34CuZnSn brazing filler metals. The surface microstructure and crystallization orientation of tin coatings were observed by scanning electron microscopy and X-ray diffraction patterns. The effect of tin content on melting temperature, wettability and tensile strength of brazing filler metals were analyzed using the differential scanning calorimetry, wetting test furnace and tensile test machine, respectively. The electrical resistivity and elongation of the brazing filler metals were also discussed after brush electroplated tin. The results show that a smooth and uniform surface morphology of tin coating with small grain size and porosity is obtained, and its crystallization orientation is (200) and (112) crystal faces. The DSC endothermic peak shift to the left, the melting temperature of brazing filler metals decreases with the increasing of tin content. The wettability area and elongation of the brazing filler metals are improved, but the electrical resistivity and tensile strength of brazing filler metals are decreased. When the content of tin in the film is 2.0 %(wt.%), the wettability area and elongation of AgCuZnSn brazing filler metals are maximum, while its melting temperature, resistivity and tensile strength are minimum.