Thread: HCl & H2O2

I was wondering if anyone could explain the purpose of the hydrogen peroxide in solution with hydrochloric acid when used for etching circuit boards. I've been using it lately (with great success) to make my own printed circuit boards. Just curious as to what exactly is going on and perhaps with some understanding I can adjust the mixture to get the best results. I'm using a 2:1 ratio now of H202 to HCI. I'm using 31.5% HCI and 3% H202.

Purely a guess, but perhaps the gas bubbles agitate the acid so that new surface is exposed constantly and the dissolved material is moved away from the surface. This would eliminate concentration gradients and speed up the process. Just a guess.

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The peroxide forms atomic chlorine in solution which is highly reactive, simialr to the formation of atomic chlorine in aqua regia.

Cool, thanks for an answer. Now I just have to figure out the best ratios.