本发明涉及一种原位合成金属覆层药皮银钎焊条及其制备方法，药皮银钎焊条由条状银钎料芯和包覆在银钎料芯外部的药皮组成，银钎料芯由Ag 10～50%、Cu 15～45%、Zn 17～40%、Sn 1～3%、P 0.1%～0.5%、Ni 0.5～2%、Si 0.1～0.3%和Li 0.1～0.3%组成；药皮由单质硼微粉5～10%、硼氢化钠5～10%、氟硼酸钾15～30%、硼酐25～40%、氟化钠10～30%、氟氢化钾2～4%、硫酸铜1～5%、聚苯乙烯0.1～2%和邻苯二甲酸二丁酯0.2～2%组成。本发明的药皮银钎焊条的钎料芯润湿性好、流动性佳、有自钎作用、锌不易挥发，且药皮活性高、吸潮性弱、碳残留少、塑韧性好等优点,特别适合钎焊不锈钢、锰黄铜等组件。

The invention relates to an in-situ synthetic metal coated silver brazing electrode and a preparation method thereof. The coating silver brazing electrode is composed of a strip-shaped silver solder core and a coating covering the outside of the silver solder core. The solder core consists of Ag 10～50%, Cu 15～45%, Zn 17～40%, Sn 1～3%, P 0.1%～0.5%, Ni 0.5～2%, Si 0.1～0.3% and Li 0.1～ 0.3% composition; the medicine skin is composed of elemental boron micropowder 5-10%, sodium borohydride 5-10%, potassium fluoroborate 15-30%, boric anhydride 25-40%, sodium fluoride 10-30%, potassium fluoride 2 ～4%, copper sulfate 1～5%, polystyrene 0.1～2% and dibutyl phthalate 0.2～2%. The solder core of the coated silver brazing electrode of the present invention has good wettability, good fluidity, self-brazing, zinc is not easy to volatilize, and the coating has high activity, weak moisture absorption, less carbon residue, good plastic toughness, etc. Advantages, especially suitable for brazing stainless steel, manganese brass and other components.