Has anyone checked the Files or Links section for info on etchants?
I had archived this post in the Files/Etchants folder:
Making copper etchant with off-the-shelf 3% Hydrogen Peroxide and 30% Muriatic Acid
Originally posted on Homebrew_PCBs by dkesterline
Others will recommend using stronger H2O2, 30% or 50%. But I had a hard time finding it without paying extremely high hazmat delivery fees, so I experimented with using the weaker medical grade.
My acid (HLC, or Muriatic) is bottled at 31 point something percent strength. From what I've read you want between 10 and 15% in the final etchant. Generally that's accomplished by diluting the acid 50-50 with water and then adding up to a couple ounces per gallon of 30% H2O2.
I have successfully used 2 parts 3% medical H2O2 with one part 31% acid - no additional water. It's pretty close to the same mix when you're done. Etching times of 7-10 minutes.
With stronger H2O2 (30% or more) you can just add a little more to regenerate the mix. With the 3% stuff it has too much water and if you add enough to regenerate the CuCl it dilutes the mix to much. To get around that I usually just regenerate with a bubbler. (aquarium pump and a plastic "air stone")
By the way, I use a rubbermaid 5161 cereal keeper as an etch tank:
http://tinyurl.com/3hbax About $5.50 at Walmart, holds a gallon and a half and can do a 9x9 inch board nicely. For a holder I usually just dangle them on a piece of plastic coated wire (cat5). Mostly just loose loops around opposite corners, but sometimes I drill a hole in the corner.
-Denny
Some minor spelling corrections and conversion to HTML by the list-owner