I use this technique all the time. I can do a 4X6 inch board in about 2 minutes. I use 1 Part HCL and 2 Parts 3% H2O2. I make just enough etchant to cover the board about 1/8 to 1/4 inch and lightly brush the surface with a foam Paint brush. I etch at room temperature. Works very well for me.
I've also tried 1 part HCL and 2 parts 12% H2O2 but the reaction was too fast and hot to control easily.
--- In Homebrew_PCBs@yahoogroups.com, "tda7000" <Tda7000@...> wrote:
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> I see some people get very fast etch times with a sponge and ferric chloride...
>
> But has anyone tried that method with the HCl and H2O2 solution, or the cupric chloride?
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> Or anything else for that matter?
>