Homebrew PCBs

I just tried the HCl/Peroxide etchant solution. 1.5 parts 40 volume 
Hydrogen Peroxide to 1 part HCl (Muriatic Acid)

WOW! A very active etch. Took under 1 minute to etch a 2 sided board.
The solution went from clear to bright green and bubbled furiuosly.
After 20 minutes its still bubbling.

If anyone has experience with this etch solution. Does it stop 
bubbling? Is it storable? Were my proportions correct?

I never was worried about undercutting , but with this etchant, I will 
definately be concerned.

TANSTAAFL!

Myc

Congratulations, you have just produced some chlorine gas.

Your proportions are wrong.
There should not be any bubbling if the proportions are right.

Your acid is probably way too strong (how many % is it?), and too much  
H2O2 too.
In short, way too much of everything ;-)

You should at least dilute the acid down to 10 or 15% with water and use  
only small amounts of H2O2 just to keep it bright green.

If it still bubbles, maybe dilute, and get some ventilation going. Don't  
let get too hot!

Read the links in the links section about CuCl, although most are more  
complicated than need be.

ST


On Wed, 08 Feb 2006 22:31:47 +0100, mycroft2152 <mycroft2152@...>  
wrote:

> I just tried the HCl/Peroxide etchant solution. 1.5 parts 40 volume
>
> Hydrogen Peroxide to 1 part HCl (Muriatic Acid)
>
>
> WOW! A very active etch. Took under 1 minute to etch a 2 sided board.
>
> The solution went from clear to bright green and bubbled furiuosly.
>
> After 20 minutes its still bubbling.
>
>
> If anyone has experience with this etch solution. Does it stop
>
> bubbling? Is it storable? Were my proportions correct?
>
>
> I never was worried about undercutting , but with this etchant, I will
>
> definately be concerned.
>
>
> TANSTAAFL!
>
>
> Myc
>

Definitely too strong! :)  

The Muriatic Acid from the Hardware store was 31% and the Hydrogen 
Peroxide from a beayt supplies store was listed at 40 volume.

I got the formula proportions from googling. I'll eat my own words, 
so much for accurate info when when googling.

Fortunately, there was very little chlorine gas. I'm familiar with 
the odor, the bubbles were probably oxygen from them excess peroxide.

I've already diluted the solution and it has stopped bubblng.

A six or seven minute etch from the reference in the files section, 
seems a lot more reasonable and controllable. I remember reading the 
about acid etching in the fioes section, a while back, before I was 
actually interested in trying it. Thanks for the reminder.

I'll try it the 'right' way next time.

And yes, I had goggles and gloves on while working with it.

Myc



--- In Homebrew_PCBs@yahoogroups.com, "Stefan Trethan" 
<stefan_trethan@...> wrote:
>
> Congratulations, you have just produced some chlorine gas.
> 
> Your proportions are wrong.
> There should not be any bubbling if the proportions are right.
> 
> Your acid is probably way too strong (how many % is it?), and too 
much  
> H2O2 too.
> In short, way too much of everything ;-)
> 
> You should at least dilute the acid down to 10 or 15% with water 
and use  
> only small amounts of H2O2 just to keep it bright green.
> 
> If it still bubbles, maybe dilute, and get some ventilation going. 
Don't  
> let get too hot!
> 
> Read the links in the links section about CuCl, although most are 
more  
> complicated than need be.
> 
> ST
> 
> 
> On Wed, 08 Feb 2006 22:31:47 +0100, mycroft2152 <mycroft2152@...>  
> wrote:
> 
> > I just tried the HCl/Peroxide etchant solution. 1.5 parts 40 
volume
> >
> > Hydrogen Peroxide to 1 part HCl (Muriatic Acid)
> >
> >
> > WOW! A very active etch. Took under 1 minute to etch a 2 sided 
board.
> >
> > The solution went from clear to bright green and bubbled 
furiuosly.
> >
> > After 20 minutes its still bubbling.
> >
> >
> > If anyone has experience with this etch solution. Does it stop
> >
> > bubbling? Is it storable? Were my proportions correct?
> >
> >
> > I never was worried about undercutting , but with this etchant, 
I will

> >
> > definately be concerned.
> >
> >
> > TANSTAAFL!
> >
> >
> > Myc
> >
>

Yes, check the links section.
The two-eyedropper method is best to check molarity sometimes while you  
start the solution.

You don't need to put in any copper or copper oxyde or something, it's OK  
to start with a slightly strong acid and add H2O2 each time in small  
quantities. The CuCl will build up all by itself from the boards.

When way too strong it is mostly oxygen gas, yes, but it also can get hot.  
HCl boils very low, and you can quickly get loads of HCl fumes. There have  
been some accidents with this etchant industrially, where it elegedly did  
"go through walls" and even killed people when way too strong. This is not  
so dangerous in household quantities, but you should not have a violent  
bubbling and you should always have it inside a second larger container  
that also takes some diluting water in an emergency.
Note that when it is so strong it will also underetch and eat all markers  
easily. I know what i'm talking about, when i started with it i once timed  
this etchant at 11 seconds a board (luckily in tiny size/quantity).

ST


On Wed, 08 Feb 2006 23:12:12 +0100, mycroft2152 <mycroft2152@...>  
wrote:

> Definitely too strong!
>
>
> The Muriatic Acid from the Hardware store was 31% and the Hydrogen
>
> Peroxide from a beayt supplies store was listed at 40 volume.
>
>
> I got the formula proportions from googling. I'll eat my own words,
>
> so much for accurate info when when googling.
>
>
> Fortunately, there was very little chlorine gas. I'm familiar with
>
> the odor, the bubbles were probably oxygen from them excess peroxide.
>
>
> I've already diluted the solution and it has stopped bubblng.
>
>
> A six or seven minute etch from the reference in the files section,
>
> seems a lot more reasonable and controllable. I remember reading the
>
> about acid etching in the fioes section, a while back, before I was
>
> actually interested in trying it. Thanks for the reminder.
>
>
> I'll try it the 'right' way next time.
>
>
> And yes, I had goggles and gloves on while working with it.
>
>
> Myc

Can you confirm / deny this formula from "files" here is appropriate? 

"I have successfully used 2 parts 3% medical H2O2 with one part 31%
acid - no additional water. It's pretty close to the same mix when
you're done. Etching times of 7-10 minutes."

I used this same formula at room temperature and etch was faster than
7-10 minutes with a bubbler. But no bubbling on its own. 

BTW, I found out the hard way, the oxygen "bubbler" you put in the
etch tank needs to be plastic with this etch solution - I used
aquarium bubbler "stones" and they disintegrated. Makes sense in
retrospect, hardware stores sell muriatic acid to clean brick and stone.  

Bob


--- In Homebrew_PCBs@yahoogroups.com, "Stefan Trethan"
<stefan_trethan@...> wrote:
>
> Yes, check the links section.
> The two-eyedropper method is best to check molarity sometimes while
you  
> start the solution.
> 
> You don't need to put in any copper or copper oxyde or something,
it's OK  
> to start with a slightly strong acid and add H2O2 each time in small  
> quantities. The CuCl will build up all by itself from the boards.
> 
> When way too strong it is mostly oxygen gas, yes, but it also can
get hot.  
> HCl boils very low, and you can quickly get loads of HCl fumes.
There have  
> been some accidents with this etchant industrially, where it
elegedly did  
> "go through walls" and even killed people when way too strong. This
is not  
> so dangerous in household quantities, but you should not have a
violent  
> bubbling and you should always have it inside a second larger
container  
> that also takes some diluting water in an emergency.
> Note that when it is so strong it will also underetch and eat all
markers  
> easily. I know what i'm talking about, when i started with it i once
timed  

> this etchant at 11 seconds a board (luckily in tiny size/quantity).
> 
> ST

Well, 2 parts mostly water will dilute the acid to roughly the 10% range,  
which i think is about right, and the amount of H2O2 could be in the right  
range too.
I don't remember clearly how much H2O2 i used at the start of the etchant,  
these days it's maybe 5ml, i never measure.

If you want to regenerate it you need stronger H2O2 than medical, so you  
can use that for starting as well (cheaper).

ST

On Thu, 09 Feb 2006 21:28:57 +0100, newaag <newaag@...> wrote:

> Can you confirm / deny this formula from "files" here is appropriate?
>
>
> "I have successfully used 2 parts 3% medical H2O2 with one part 31%
>
> acid - no additional water. It's pretty close to the same mix when
>
> you're done. Etching times of 7-10 minutes."
>
>
> I used this same formula at room temperature and etch was faster than
>
> 7-10 minutes with a bubbler. But no bubbling on its own.
>
>
> BTW, I found out the hard way, the oxygen "bubbler" you put in the
>
> etch tank needs to be plastic with this etch solution - I used
>
> aquarium bubbler "stones" and they disintegrated. Makes sense in
>
> retrospect, hardware stores sell muriatic acid to clean brick and stone.
>
>
> Bob