The major work components of the flux is rosin, rosin tin 260 degrees Celsius will not decompose tin bath temperature is not too high. Flux is a to promote welding chemicals. Solder, it is an indispensable auxiliary materials, its role is extremely important. (1) dissolving the oxide film of the welding surface of the base material In the atmosphere, by the welding surface of the base material is always oxide film is covered with a thickness of approximately 2 × 10-9 2 x 10-8M. In welding, the oxide film inevitably prevent solder wetting of the base material, welding is not performed correctly and must therefore be in the base material surface is coated with flux, so that the surface of the base material of the oxide reduction, so as to achieve the purpose of the elimination of an oxide film . (2) to prevent the re-oxidation of the base material is welded The base material in the welding process requires heating the metal surface will be accelerated oxidation at high temperatures, the liquid flux covering the base material and the surface of the solder prevents their oxidation. (3) reduce the surface tension of the molten solder The molten solder has a certain surface tension, like the rain falls on a lotus leaf, due to the surface tension of the liquid will immediately polyethylene to form a bead-like droplets. The surface tension of the molten solder will prevent the flooding, the impact of wetting normal to the surface of the base material. When the flux covering the surface of the molten solder, can reduce the surface tension of the liquid solder, and the wetting properties were improved. (4) the protection of the welding base metal surface The material to be welded in the welding process has destroyed the original surface protective layer. Good flux after soldering, and quickly return to the role of the protection of welding consumables.