That is, the extra oxygen in solution from the peroxide is oxidizing the copper metal, in presence of the acid, to make copper (II) chloride. The whole point of this instructable is that you don't throw it away, but use the dissolved copper forevermore as your long-run etchant.īefore there's much copper dissolved in the solution, Cu + 2 HCl + H2O2 -> CuCl2+ 2H2O is the dominant net reaction. Turns out that hydrochloric/peroxide is a common home-brew etchant (and I've re-re-invented the wheel, again) but I guess that people got so used to throwing away their 'spent' etchant that they don't think about re-using it. So we can make one etchant that makes another etchant that's infinitely re-chargeable. Dissolving copper is the name of the etching game. You didn't have any cupric chloride yet, but you can make it by dissolving copper. To make the cupric chloride solution, he dissolves a bunch of copper wire in hydrochloric acid, and mentions maybe using hydrogen peroxide to speed up the oxidation, but doesn't go into detail. His data on etching speeds is great, and his simple titration procedure for maintaining the acidity of the solution is pretty nice. The website's got a lot of good chemistry info on cupric chloride etching. Sounds cheap and environmentally friendly to boot. Cupric chloride can be re-used indefinately by topping up the acid levels and adding oxygen (bubbled in from the atmosphere). I stumbled on this idea when I saw this website: Etching with Air Regenerated Acid Cupric Chloride by Adam Sechelle. Please leave a comment if you've got any corrections and/or additions to this stuff!) I got seven words for you: Copper Chloride in Aqueous Hydrochloric Acid Solution! (Exclamation point!)īut how're you going to get CCiAHAS? Conveniently enough, by starting out with a simple two-ingredient starter etchant, and doing a bunch of etching.

Wouldn't it be nice if there were an etchant that you could re-use indefinitely so that you don't have to worry about disposing of the copper, and that could be made in lifetime supply for like $10.00 with ingredients bought at hardware and drugstores? (And it's prettier too.) (For instance: How to Dispose of Ferric Chloride in this FAQ. This dissolved copper is an environmental problem, and you can't just pour it down the drain (legally) - you're supposed to take it to a hazardous waste facility.

However, once you've etched a board with it, you're left with a solution with a bunch of copper chloride in it. It's easy enough to come by, and the Ferric by itself is no big environmental problem. Ferric chloride is a traditional home-use circuit board etchant.

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