Homebrew PCBs

In the files section are instructions for
making etchant from muratic acid and hydrogen peroxide.

Sounds like something interesting to try.

As I understand it, you stick in the board and the copper goes
into solution.  You regenerate the solution by bubbling air
through it.  Ok, so where does all that copper go when you regenerate???
Thanks, mike

>From: "gettingalongwouldbenice" <gettingalongwouldbenice@...>
>Reply-To: Homebrew_PCBs@yahoogroups.com
>To: Homebrew_PCBs@yahoogroups.com
>Subject: [Homebrew_PCBs] Regenerating etchant??
>Date: Sun, 14 Nov 2004 15:06:04 -0000
>
>
>
>In the files section are instructions for
>making etchant from muratic acid and hydrogen peroxide.
>
>Sounds like something interesting to try.
>
>As I understand it, you stick in the board and the copper goes
>into solution.  You regenerate the solution by bubbling air
>through it.  Ok, so where does all that copper go when you regenerate???

It's converted to cupric chloride, which is quite a good etchant in it's own 
right, if the pH is correct.

Leon

When you Etch with Ferric Chloride, you Create Cupric Chloride.
I Can't believe Cupric Chloride will etch copper at all. But if 
you've added enough muratic acid, that acid will do the etching, all 
by itself.

Gary

--- In Homebrew_PCBs@yahoogroups.com, "Leon Heller" 
<leon_heller@h...> wrote:
> 
> 
> >From: "gettingalongwouldbenice" <gettingalongwouldbenice@y...>
> >Reply-To: Homebrew_PCBs@yahoogroups.com
> >To: Homebrew_PCBs@yahoogroups.com
> >Subject: [Homebrew_PCBs] Regenerating etchant??
> >Date: Sun, 14 Nov 2004 15:06:04 -0000
> >
> >
> >
> >In the files section are instructions for
> >making etchant from muratic acid and hydrogen peroxide.
> >
> >Sounds like something interesting to try.
> >
> >As I understand it, you stick in the board and the copper goes
> >into solution.  You regenerate the solution by bubbling air
> >through it.  Ok, so where does all that copper go when you 
regenerate???
> 
> It's converted to cupric chloride, which is quite a good etchant in 
it's own 

> right, if the pH is correct.
> 
> Leon

gettingalongwouldbenice wrote:

> 
> In the files section are instructions for
> making etchant from muratic acid and hydrogen peroxide.
> 
> Sounds like something interesting to try.
> 
> As I understand it, you stick in the board and the copper goes
> into solution.  You regenerate the solution by bubbling air
> through it.  Ok, so where does all that copper go when you regenerate???
> Thanks, mike
> 
> 
Thats not the full story, the regeneration reaction consumes both oxygen 
(from air) and free hydrochloric acid. Overall it is;

CuCl + O + 2HCl -> CuCl2 + H20

--- In Homebrew_PCBs@yahoogroups.com, Adam Seychell <a_seychell@y...>
wrote:
> Thats not the full story, the regeneration reaction consumes both
oxygen 
> (from air) and free hydrochloric acid. Overall it is;
> 
> CuCl + O + 2HCl -> CuCl2 + H20

This doesn't balance.  where does the other Cl go?

But the reaosn for my post is a question about this process. I can
bubble for 48+ hrs and get slow etching ( about 1 hr) but if I add 50
mL of 35% H2O2 (2.5 L of etchant) it takes about 1/3 the time.  Acid
level look right and SG is getting towards 1.17.  I think there must
be some other reaction taking place - any one able to shed light on this?

Phil

>From: "Phil" <phil1960us@...>
>Reply-To: Homebrew_PCBs@yahoogroups.com
>To: Homebrew_PCBs@yahoogroups.com
>Subject: [Homebrew_PCBs] Re: Regenerating etchant??
>Date: Mon, 15 Nov 2004 03:01:27 -0000
>
>
>
>--- In Homebrew_PCBs@yahoogroups.com, Adam Seychell <a_seychell@y...>
>wrote:
> > Thats not the full story, the regeneration reaction consumes both
>oxygen
> > (from air) and free hydrochloric acid. Overall it is;
> >
> > CuCl + O + 2HCl -> CuCl2 + H20
>
>This doesn't balance.  where does the other Cl go?

>
>But the reaosn for my post is a question about this process. I can
>bubble for 48+ hrs and get slow etching ( about 1 hr) but if I add 50
>mL of 35% H2O2 (2.5 L of etchant) it takes about 1/3 the time.  Acid
>level look right and SG is getting towards 1.17.  I think there must
>be some other reaction taking place - any one able to shed light on this?

Are you heating it? CuCl2 needs to be warm to work properly.

Leon

--- In Homebrew_PCBs@yahoogroups.com, Adam Seychell <a_seychell@y...> wrote:
> gettingalongwouldbenice wrote:
> 
> > 
> > In the files section are instructions for
> > making etchant from muratic acid and hydrogen peroxide.
> > 
> > Sounds like something interesting to try.
> > 
> > As I understand it, you stick in the board and the copper goes
> > into solution.  You regenerate the solution by bubbling air
> > through it.  Ok, so where does all that copper go when you regenerate???
> > Thanks, mike
> > 
> > 
> Thats not the full story, the regeneration reaction consumes both oxygen 
> (from air) and free hydrochloric acid. Overall it is;
> 
> CuCl + O + 2HCl -> CuCl2 + H20

Chemistry is good...but...let's do a thought experiment.
Keep etching and regenerating until you've etched a ton of copper
in your pint of etchant.  The copper can't still be in solution.
Where is it?

If it's using up the HCl, then we need to add HCL???  Which means
it ain't regenerating by air alone???  Looks like need to add
HCl.  then there's too much water, so gotta add more H2O2.
Which is what we had to do to make the stuff in the first place.
So, "regeneration" don't seem to be adding any value?????

Still confused,
mike

--- In Homebrew_PCBs@yahoogroups.com, "Leon Heller" <leon_heller@h...>
wrote:
...
> 
> Are you heating it? CuCl2 needs to be warm to work properly.
> 
> Leon

Is that a good idea?  HCl has a bp of around 50C.  I dont think HCl
vapor is a good thing to have around.

>From: "Phil" <phil1960us@...>
>Reply-To: Homebrew_PCBs@yahoogroups.com
>To: Homebrew_PCBs@yahoogroups.com
>Subject: [Homebrew_PCBs] Re: Regenerating etchant??
>Date: Mon, 15 Nov 2004 07:29:19 -0000
>
>
>
>--- In Homebrew_PCBs@yahoogroups.com, "Leon Heller" <leon_heller@h...>
>wrote:
>...
> >
> > Are you heating it? CuCl2 needs to be warm to work properly.
> >
> > Leon
>
>Is that a good idea?  HCl has a bp of around 50C.  I dont think HCl
>vapor is a good thing to have around.

If CuCl2 etchant is correctly made up, there will be very little free HCl 
around, it'll all be in the form of ions. Similar to FeCl3 solution, that 
contains a lot of H and Cl ions, but can be heated quite safely.

Leon

Leon