Flux: A chemical that aids and facilitates the soldering process, while protecting and preventing oxidation reactions during the soldering process. Flux can be divided into solid, liquid and gas. There are mainly "auxiliary heat conduction", "removal of oxides", "reduce the surface tension of the welded material", "remove the surface oil of the welded material, increase the welding area", "prevent re-oxidation" and other aspects. There are two key functions in the aspect: "removing oxides" and "reducing the surface tension of the welded material".
