Homebrew PCBs

Randy, with 17% H2O2 and 34% HCL the ratio is about even for the
reaction.  With 3% H2O2 and 34% HCL you need about 5 times as much
peroxide as HCL.

You can use the calculator I wrote to play with the numbers:
http://www.totse2.com/easy-e/cupricchloride.html

-- 
Erik L. Knise
Seattle, WA

On Sun, Apr 10, 2011 at 2:49 PM, Harvey White <madyn@...> wrote:
> On Sun, 10 Apr 2011 19:40:39 -0000, you wrote:
>
>>ok .. thanks Harvey ..
>>Does it also change color when it calms down?
>>When I added more 3% peroxide .. it changed color..
>>and slowed down the etching process immensely.
>>Didnt seem like I added all that much either..
>
> As I remember, it started clear, then turned light and transparent
> green.  As the etchant changes, it goes to an olive color/dark green.
> The 17% peroxide was more than needed, it is usually mixed in that
> ratio using 3%.
>
> You diluted it a bit, and that probably needed to be done.
>
> Adding more peroxide later will tend to turn it transparent green.  As
> it ages, it does need oxygen to make the reaction run, that's the
> function of the peroxide.
>
> Harvey
>
>>
>>
>>--- In Homebrew_PCBs@yahoogroups.com, Harvey White <madyn@...> wrote:
>>>
>>> On Sun, 10 Apr 2011 10:57:23 -0700 (PDT), you wrote:
>>>
>>> >ok .. 17% peroxide ..
>>> >34 % muriatic acid ..
>>> >mixed 3 : 1 ..
>>> >never seen copper come off a board that fast .. ever ..
>>> >did it outdoors .. respirator .. goggles .. gloves ..
>>> >anyways.. should the solution be bubbling even AFTER I take the
>>> >board out ?? whats it mean .. I put more 3 % peroxide in it ..
>>> >calmed it down ..  is it safe?
>>>
>>> The peroxide is going to decompose and release oxygen, that's what you
>>> see.  It will calm down in about 30 days to the point where it doesn't
>>> want to do much.
>>>
>>> Regenerate it by bubbling oxygen through it.  It eventually changes to
>>> a different kind of etchant, takes longer, is  a bit more mild in
>>> terms of action.
>>>
>>> Nothing to worry about in the proportions you used.
>>>
>>> Harvey
>>>
>>> >
>>> >Randy
>>> >
>>> >