I'm trying to reclaim the metals on circuit boards and the vast majority is underneath the plastic coating. It is a brittle plastic that chips off in small flakes when etched but that process will lose to much of the precious metal.


This seems to be a popular question judging from some Google queries.

Printed circuit boards are made of a variety of materials, and from what I understand, the specifics may vary somewhat based on the specific needs of the product and the manufacturer. For example, in some cases, I know the PCBs are coated with special anti-static coatings to prevent delicate RAM and CPU chips from being damaged (e.g., this article found via Google among others).

So I doubt there's a definite solution - more likely you'll need to try several different things.

That said, there's a recent article that looks very interesting about separating parts by dissolving and swelling the plastic resins with DMSO: "Dissolution of Brominated Epoxy Resins by Dimethyl Sulfoxide To Separate Waste Printed Circuit Boards" Environ. Sci. Technol., 2013, 47 (6), pp 2654–2660.

Certainly DMSO is considered a near-universal solvent and will swell many polymers. So I'd probably try that first.

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    $\begingroup$ The usual precautions for DMSO apply. It quickly penetrates the skin barrier, as does everything that's dissolved in it. $\endgroup$ Oct 13 '14 at 16:08
  • $\begingroup$ @AbelFriedman Yes, very good point. Since it's a universal solvent, it's tricky to work with safely. DMSO will penetrate latex or nitrile gloves quickly. I usually recommend double gloves, which gives you sufficient time to remove the gloves before the DMSO contacts your skin. $\endgroup$ Oct 13 '14 at 16:18
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    $\begingroup$ I've not tried with solder mask, but DMSO or N-Methyl-2-pyrrolidone work great for stripping most photoresists. The trick is, you generally need to heat them. If you keep it under ~80 °C, it's safer because it's under the flash points of the solvents, but something like 130 °C works quite well. $\endgroup$ Oct 13 '14 at 18:22

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