Archive of the former Yahoo!Groups mailing list: Homebrew PCBs

This afternoon I finally got around to mixing up a small batch of
the 1/3 HCl + 2/3 H2O2. I've read the positive reviews on that recipe
here, but was really surprised/impressed at the results.
My usual initial test is to cut a small strip of .005" brass and
wave the end around in the solution, and it dissolved in record time. So,
I set up a sheet with some photoresist (laminated dry-film), burned my
favorite test file into the resist, developed it and popped it into the
beaker. I hesitate to say that it took minutes to etch, it would make
more sense to describe it as seconds. Since the test file has two parts
panels, I dropped the second one in and it was nicely finished in short
order. The guy that craves these parts is going to be really pleased, as
am I.

Question:
The solution total was about 225 ml, and the brass sheet was etched
one sided with an etch area of a couple of square inches. Afterward the
solution was quite hot and bubbling like soda pop on the stove. I put it
in a cold water bath to cool it down, but I have to wonder - is there the
possibility of a runaway reaction and what is the result?

Oh, and I'm sure this is common knowledge to the rest of you, but on
say, a 1 oz and 2 oz board, what are the copper thicknesses?

Thanks,
-Gary