Novel non-corrosive brazing flux used for silver brazing filler metal or copper-phosphorus-silver brazing filler metal

The invention provides a novel non-corrosive brazing flux used for a silver brazing filler metal or a copper-phosphorus-silver brazing filler metal, and aims to solve the technical problems of easy moisture absorption, easy caking, toxic gas generation, corrosivity and the like of the brazing flux in the prior art. The brazing flux provided by the invention comprises the following components in percentage by weight: 10 to 40 percent of lithium fluoride, 20 to 50 percent of boron anhydrous and the balance of potassium tetraborate. Matched with the corresponding brazing filler metal, the brazing flux of the invention is suitable for brazing of low-carbon steel, stainless steel, copper and copper alloys.