Send To A Friend Fluxes

The purpose of flux is to facilitate the soldering process. The main obstacles to a successful solder joint is an impurity at the site of the joint consisting of dirt, oils or oxidation. The impurities can be removed by mechanical cleaning or by chemical means, but the elevated temperatures required to melt the filler metal (the solder) encourages the work piece (and the solder) to re-oxidize. This effect is accelerated as the soldering temperatures increase and can completely prevent the solder from joining to the work piece. Some fluxes go beyond the simple prevention of oxidation and also provide some form of chemical cleaning (corrosion).

For many years, the most common type of flux used in electronics (soft soldering) was rosin-based, using the rosin from selected pine trees. It was ideal in that it was non-corrosive and non-conductive at normal temperatures but became mildly reactive (corrosive) at the elevated soldering temperatures.

Fluxes also act as a wetting agent in the soldering process, reducing the surface tension of the molten solder and causing it to flow and wet the workpieces more easily.

Fluxes for soft solders for industrial use(non-electronics):

Plumbing, automotive and industrial applications, among others, typically use an acid-based flux which provides cleaning of the joint. When joining Stainless Steel to any other metal, an acid flux must be used.  Our acid based Fluxes are the #22 and #75 These fluxes cannot be used in electronics because they are conductive and because they will eventually dissolve the small diameter wires. 

Fluxes for soft solders for use with electronics are currently available in three basic formulations:

Water-soluble fluxes - higher activity fluxes designed to be removed with water after soldering like the #30 Flux.

No-clean fluxes - mild enough to not "require" removal due to their non-conductive and non-corrosive residue. These fluxes are called "no-clean" because the residue left after the solder operation is non-conductive and won't cause electrical shorts; but they can leave a white of clear residue. These residues can be removed with alcohol

Traditional rosin fluxes - available in non-activated (R) #97, mildly activated (RMA) #99 and activated (RA) #100 formulations. RA and RMA fluxes contain rosin combined with an activating agent, typically an acid, which increases the wettability of metals to which it is applied by removing existing oxides. The residue resulting from the use of RA flux is corrosive and must be cleaned. RMA flux is formulated to result in a residue which is not significantly corrosive, with cleaning being preferred but optional.

We have a full range of soldering and brazing fluxes including the popular fluxes from Superior Flux Company.  If you need help choosing the correct please contact us!