General Question

warpling's avatar

Why does carbon attract solder smoke?

Asked by warpling (841points) December 28th, 2008

I was told in grade school that solder smoke seems hard to escape because it’s actually attracted to carbon. Solder fume extractors usually have some sort of carbon filter to pull out the toxins I assume, but how does this work!?

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4 Answers

srmorgan's avatar

I haven’t studied this in a while but solder used to be a combination of lead and some type of flux which made the lead flow and cover the connection of copper to copper.

If the heat was creating smoke, you got lead oxide (PbO) (not sure of the chemical valences, it has been a while) which is going to be toxic. The filters are there because the fumes are pulled by an exhaust system that uses carbon as a filter.

I don’t have time to look it up but the main manufacturer of wave solder equipment (heavy duty solder set up on green boards) was Electrovert and they may now be called Speedline Technologies. Google one of those names and see if anything helpful comes up.


warpling's avatar

Oh ok, so something to do with the valence of PbO and C I’d guess.

Harp's avatar

Smoke produced by soldering with a soldering iron contains virtually no lead. The temperature is not high enough (there is the potential that soldering with a torch, as plumbers do, could cause some vaporization if the solder were exposed to the flame of the torch).

The source of the smoke in soldering is the rosin (colophony) used to flux the solder. It’s the rosin fumes that provoke respiratory ailments. This is an organic compound of a kind that’s readily bound by carbon (carbon has no particular bonding affinity for lead). The mechanism by which this bonding occurs is called the Van der Waals force, which is not a covalent bond.

srmorgan's avatar


so much for my high school chemistry classes…..


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