The brazing is used as a filler metal with a melting point below the base material. The filler metal is melted when heated and filled and kept in the gap between the wetting and capillary action. The parent material is in the solid, and the brazing joint is formed by the mutual diffusion between the liquid filler metal and the solid material. The brazing has little influence on the physical and chemical properties of the parent material, the welding stress and the deformation are small, the dissimilar metal with large welding performance can be completed at the same time, the joint appearance is beautiful and neat, the equipment is simple, and the production investment is small. But the brazing joint has low strength and poor heat resistance. Applications: carbide cutters, drilling bits, bicycle frames, heat exchangers, ducts and various containers, and so on. In the manufacture of microwave waveguides, electronic tubes and electronic vacuum devices, brazing is even the only possible connection method.