Gas flux: A chemical substance that can help and promote the welding process while providing protection, gas flux prevents oxidation reactions. Flux can be divided into solid, liquid, and gas. It has several aspects such as 'assisting heat conduction', 'removing oxides', 'reducing the surface tension of welding materials', 'removing oil stains from welding materials, increasing the welding area', and 'preventing re-oxidation', among which two key functions are 'removing oxides' and 'reducing the surface tension of welding materials'.

The main active ingredient in gas flux is rosin, which decomposes at around 260 degrees Celsius; the temperature of the tin bath should not be too high. Gas flux is a chemical substance that promotes welding. It is an indispensable auxiliary material in solder, and its role is extremely important. 1) Dissolving the oxide film on the surface of the base metal to be welded. In the atmosphere, the surface of the base metal to be welded is always covered by an oxide film, with a thickness of about 210-9210-8m. During welding, the oxide film inevitably prevents the solder from wetting the base metal, thus hindering normal welding. Therefore, it is necessary to apply flux on the surface of the base metal to reduce oxides on the surface, thereby eliminating the oxide film. 2) Preventing re-oxidation of the base metal during welding requires heating; at high temperatures, the metal surface will accelerate oxidation, so covering the liquid flux on the surfaces of both base metal and solder can prevent them from oxidizing. 3) Reducing the surface tension of molten solder. The surface of molten solder has a certain tension; just like raindrops on a lotus leaf, due to liquid surface tension, they immediately coalesce into bead-like droplets. The surface tension of molten solder will prevent it from spilling onto the base metal surface, thus affecting normal wetting. When flux covers the surface of molten solder, it can reduce the surface tension of liquid solder.Gas fluxSignificantly improves wettability.

　　Gas fluxThe protective effect on the surface of welded base materials: During welding, the original protective layer on the material being welded has been destroyed. After welding, good flux will quickly restore its protective function for the welded material. There are many types of gas fluxes, generally divided into inorganic series, organic series, and resin series. Inorganic series fluxes have strong chemical action and excellent welding performance but have significant corrosive effects and belong to acidic fluxes. Because they are soluble in water, they are also called water-soluble fluxes, including inorganic acids and inorganic salts.

The main components of inorganic acid fluxes include hydrochloric acid and hydrofluoric acid. The main components of inorganic salt fluxes include zinc chloride and ammonium chloride. After use, they must be cleaned immediately and thoroughly because any halides remaining on welded parts can cause severe corrosion.Gas fluxThis type is usually only used for welding non-electronic products; it is strictly prohibited to use this inorganic flux during the assembly process of electronic devices.