Plumbing flux vs. Electronic flux

CLamb

I'm trying to understand the reasons why different flux is used for soft soldering in plumbing and in electronic work. In plumbing the flux is mostly Zinc Chloride. In electronic work the flux is mostly resin. I know Zinc Chloride isn't suitable for electronics because the chlorides can adversely affect electronic components. Why isn't electronic flux suitable for plumbing? I know that electronic flux is less aggression than Zinc Chloride but the copper tube and fittings are well cleaned before soldering therefore I wouldn't expect this to be an issue. Is it perhaps that Zinc Chloride is water soluble and therefore easier to clean off after the soldering is done?

Jamie Hall

Sort of all of the above. Electronic flux is non-corrosive, which is why it is used in electrical work. To say that the corrosion from plumbing flux adversely affects electrical components is a wild understatement. "Destroys" might be somewhat closer to the mark. But plumbing flux does a much better job of cleaning off oxidation -- which is the objective of the exercise, after all -- and at least in my experience is a good deal less sensitive to being overheated.

Gordy

In electronics you are cleaning, and soldering in one step. The soldering is usually a surface bond of components. With plumbing the flux cleans the fittings, and gets the solder to flow into the cup of the fitting.