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

There seems to be some confusion with "CuCl2" etching. There appears to
be two ways to etch. One is with chemical oxidizer H2O2 and one without.
If there is only HCl and H2O2 then etching cannot really be called
"CuCl2" since no copper is present in solution. I found that when
etching with only CuCl2 then the concentration needs to be very high
with an SG 1.30 +-0.05 , Regeneration this acidic CuCl2/CuCl solution
with either air or H2O2 probably makes no difference. ∗But∗ when excess
H2O2 is added in the presents of HCl then CuCl2 may not play a big roll
in the etch rate. Something else is happening in this reaction since the
etch rate shoots up dramatically.

So if trying to etch with excess H2O2 + HCl then CuCl2 is less
important. If you are etching exclusively with CuCl2 then its
concentration becomes very relevant.