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.