Instructables

What is soldering flux used for?


Just wanted to know.

iceng3 years ago
I enjoy the aroma of English 5 core rosin solder.
Others have answered you very well.
Sniff on :)

A
seandogue iceng3 years ago
Blucghk!

I've personally had my fill of rosin fumes. I use a fume catcher (basically a muffin fan with an activated charcoal filter on the inlet side) when I solder these days. The fumes are terrible for your sinuses.
iceng seandogue3 years ago
Five core English solder aroma is sweet as a miniscule drop of 
trichloroethylene tastes on the tip of your tongue :-þ

A
seandogue iceng3 years ago
You, my friend, are happily deranged ;-)
Flux removes oxides coatings from the metals you are joining. Oxides prevent the solder from "wetting" the metals to be joined, so they have to be removes. Soldering dissolves tiny amounts of the metal of the joints into the solder and contamination stops that happening.

Steve
+1

Couldn't have said it better (if at all ;-)

Just to add a word of warning: Never use a plumbing flux for electronic soldering. It will continue to eat away any oxides (and metals in PCB traces and delicate wires) long after the soldering and kill your circuits that way. Electronic solder with a flux-resin core is the way to go.
+1 for best description of the actual purpose.
seandogue3 years ago
acidic fluxes partially strip existing oxides from the surface of a metal, (these are used almost exclusively for plumbing and related welding/brazing/soldering processes.

For electronics and most electrical soldering, non-acidic rosin flux  is used.

AFAIK, the primary purpose of flux (in general)  is to prevent oxidation during the soldering/brazing/welding process.
It basically makes the solder stick.