The functional part of the flux includes: matrix, remover and surfactant.
The matrix is the main component of the flux, which controls the melting point of the flux. It melts to cover the surface of the solder joint and acts as a barrier to air. At the same time, it is a solvent for other functional components.
The film removing agent removes, crushes or loosens the surface oxide film of the base material by a physicochemical process, so that the molten solder can wet the surface of the fresh base material.
The surfactant can further reduce the interfacial tension between the molten solder and the base metal, and promote the molten solder to spread well on the surface of the base material.
The main role of flux:
(1) The oxides on the surface of the base metal and the liquid solder are removed during the brazing process to create conditions for the spreading of the liquid solder.
(2) Covering the surface of the base metal and the solder with a thin layer of liquid to protect the air.
(3) It acts as an interface to improve the wetting and spreading properties of the liquid solder on the surface of the base metal.