Soldering Question - Flux on Wire?

msg

I was just playing around with tinning some cheapo speaker cable. I noticed that it seemed to be oxidized up under the jacket before I snipped them, but now I'm not sure, as it may just have been dried up flux that didn't get any solder, because that kinda happened again after I tinned them new.

My questions are:

1. What happens to the flux on a wire as solder is applied?
2. It seems to be bad to have flux on a wire without the application of solder. Is it? Does flux oxidize the wire? Seems that it etches it or something to prepare it to accept the solder?

Thanks in advance, and I'll take my answer off the air, Chuck.

SCompRacer

1. Flux dissolves oxides on the metal surface aiding solder flow and acts as an oxygen barrier by coating the hot surface. It ends up displaced by the solder as a layer on top of the joint.

2. Depends. Rosin flux is still mild organic acids. I like to remove rosin flux after soldering on boards and wires. On boards it can lead to attraction of dust/dirt that can make a low level path for current flow. You'll also get varying opinions from experts on that too. You want to use high percentage (99%) isopropyl alcohol to clean as it has the least amount of water in it. They also sell flux remover. I've used brake cleaner on a rag too.

Where you have to watch mostly is when you buy a tin of flux. If you have to resolder something you apply some flux. An application of flux can also make de-soldering easier.

A wiki...the chart at bottom of page lists flux types from strongly corrosive to non corrosive.

https://en.wikipedia.org/wiki/Flux_(metallurgy)

skrol

Cheap wire can oxidize under the insulation. When I bought my Monitor 5A's the guy threw in some heavy gauge speaker wire that he said was Monster but not sure. The stuff is green from one end to the other.