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Homebrew PCBs

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Re: Muriatic Acid and 3% Hydrogen Peroxide First Attempt

2014-04-10 by <leeleduc@...>

Are you putting the board in the etchant and letting it sit there?. It will take the board a long time to etch this way even if you rock or agitate the tray. When you first put the board into the etchant, you will see the shiny copper turn matte or dull. This (oxide?) layer prevents fresh etchant coming into contact with the copper and slows down the process.

I suggest you place your board copper side up and cover it with 1/4 to 1/2 inch with etchant. Gently and continuously brush the board with a small (2 to 3 inch) foam paint brush. This will brush away the dull layer and expose fresh copper to fresh etchant. This is a cleaner method I came up with after trying Pulsars "Sponge etching" method detailed at http://www.pcbfx.com/main_site/pages/tech_support/no_etching_tank.html

I typically etch a 4 by 6 inch board in a few minutes using Lowes 31% HCL and 3% H2O2 from the supermarket. Make sure your chemicals are fresh. H2O2 can degrade with temperature and time. Higher concentrations of H2O2 will give you a faster etch using this method.

Give it a try.

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