Homebrew PCBs

On Sat, 28 May 2016 21:51:40 -0400, you wrote:

>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.

Thanks, that's what I need.  I understand regenerating the etchant. If
I supply chloride ions (say from salt), think it will work?  I'm
guessing that the HCL is what makes CuCl so destructive to things like
nylon.

any opinions?

Harvey


> 
>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
>> >> 
>> >> 
>> >> 
>> 
>> 
>>