Hakko - What To Do About Flux Residues

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Soldering fluxes invariably leave a trace of residue behind them after doing their job of cleaning corrosion from those surfaces being soldered. Most of them also generate nasty fumes, at least when heated, and it's recommended that you use a fume-extraction device to keep these fumes away from the operator's breathing apparatus.

Semi-aqueous cleaning of rosin1 fluxes.

Aqueous saponifiers have been available and have been successfully used by electronic assemblers for decades. Saponifiers are alkaline materials that react with rosin, forming water washable soaps. The soaps created by this reaction must be washed off the assemblies with generous amounts of water. Saponifiers that are available to the industry are available in concentrates suitable for use in both batch type and in-line spray cleaning equipment. A good saponifier will have both an anti-foaming agent and an anti-smutting agent incorporated into its chemistry. The anti-foaming agent will keep the amount of foam manageable in automated cleaning equipment. The anti-smutting agent prevents discoloration from appearing on certain metals such as anodized aluminum, which may react with the alkalis in the saponifier.

Semi-aqueous cleaners use terpenes as the cleaning agents. The fumes are not particularly toxic but have an overpowering reek; turpentine is a concentration of terpenes and oils, and we all know what that smells like...

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