What Is Solder Flux Used for?

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Solder flux is a type of metallurgy component used when soldering two metals together. The flux is an inert substance that prevents the formation of metal oxides at extreme temperatures.


Soldering is the process in which two or more metals are joined together using a flux in between. The soldering process usually occurs below 800-degrees F.


Brazing is the process of joining metal using a flux in between when the melting temperatures are above 800-degrees F.


Welding is the process of joining separate metals by melting the pieces together while adding a flux in between.


This is a filler metal used in soldering, brazing and welding, to prevent oxidation of the surfaces of the metals being joined. Oxidation weakens the process of joining the metals together. The flux used in the different processes makes the joints stronger.

Flux Types

There are different types of flux, depending on the metals being joined. Choosing an appropriate flux minimizes joint failure and cleans the joint. Fluxes used in soldering are sometimes referred to as solder or solder flux.