In the course of electronic soldering, the metal surface will form a layer of oxide film after heated and exposed to air. The higher is the temperature, the thicker is the oxide layer. This layer of oxide film prevents liquid tin solder from infiltrating the metal, just as oil on the glass will prevent water from infiltrating the glass. Rosin flux is a special material for removing oxide film.
1. Oxidation Film Removal
Essentially, the substances in the rosin flux will undergo a reduction reaction to remove the oxide film. And the reaction produces suspended slag floating on the surface of the solder.
2. Prevent Oxidation
After melting, the rosin flux floats on the solder surface to form an isolation layer and prevents the oxidation of the soldering surface.
3. Reduce the Surface Tension
Rosin flux is able to increase the fluidity of the solder and help the solder to wet the weldment.