Homebrew PCBs

Harvey,

The hydrogen peroxide alone will NEVER etch copper. it is H2O2 (very strong oxidizer),
so the only thing that it could do is to oxidize a thin layer of copper (black).

In order to etch, you need ions Cl- to create green cupric chloride CuCl2 (dissolve in water).
So you need the hydrochloric acid (muriatic) to convert the copper oxide to cupric chloride.

Hence the combination Hal-H2O2 that will etch copper very fast.
To regenerate the etchant, you use a bubbler that will bring O2 ( O= ions) in the solution.
 
My $0.02,
Jean-Paul
N1 JPL



> On May 28, 2016, at 6:05 PM, Harvey White madyn@... [Homebrew_PCBs] <Homebrew_PCBs@yahoogroups.com> wrote:
> 
> On Sat, 28 May 2016 16:50:45 -0400, you wrote:
> 
> >If you use the Beauty Shop peroxide be aware that the etching is violently exothermic. Lots of heat and fumes. The etching goes very fast. Done in seconds. 
> 
> I'd be using it to boost the O2 concentration of the etchant, which
> hopefully works, since the peroxide by itself I can see as not being
> much different from the ammonium persulphate except for the ammonia
> ions (and sulphate ions).
> 
> In theory, the drugstore peroxide might etch sufficiently by itself,
> then the question is either to put a gallon or so of that in, or
> refresh it by the beauty shop peroxide.
> 
> I'm trying to avoid the CuCl etchant, or at least, the HCL part of it.
> 
> Harvey
> 
> >
> >I use the drug store version mixed 2:1 with muriatic acid from the hardware store. Instead of immersing the board I use a sponge and gently rub the copper. This allows you to control where you need the etching. Obviously, wear gloves.
> >
> >I'm not sure who first described this technique, but it gives you good control and only takes a few minutes. It also lets you use a very small amount of etchant.  
> >
> >Mark
> >
> >Sent from my iPhone
> >
> >> On May 28, 2016, at 2:53 PM, John Ferrell jferrell13@... [Homebrew_PCBs] <Homebrew_PCBs@yahoogroups.com> wrote:
> >> 
> >> 
> >> 
> >> Read the MDS. It is pretty safe stuff. About a million years ago I was a Lab Tech and HCl was used to wash ink off our hands.
> >> Beauty shop peroxide is about 30% and over $30 per gallon. The drug store stuff works and $1 per Qt. I wash all wounds with the $1 peroxide and some people use it for mouth wash.
> >> It also leaves bleach dot on you clothing.
> >> -- 
> >> John Ferrell W8CCW
> >> Julian NC 27283
> >> It is better to walk alone,
> >> than with a crowd going the wrong direction.
> >> --Diane Grant
> >> 
> >> 
> >> 
> 
> 
>