Homebrew_PCBs

This afternoon I finally got around to mixing up a small batch of
the 1/3 HCl + 2/3 H2O2. I've read the positive reviews on that recipe
here, but was really surprised/impressed at the results.
My usual initial test is to cut a small strip of .005" brass and
wave the end around in the solution, and it dissolved in record time. So,
I set up a sheet with some photoresist (laminated dry-film), burned my
favorite test file into the resist, developed it and popped it into the
beaker. I hesitate to say that it took minutes to etch, it would make
more sense to describe it as seconds. Since the test file has two parts
panels, I dropped the second one in and it was nicely finished in short
order. The guy that craves these parts is going to be really pleased, as
am I.

Question:
The solution total was about 225 ml, and the brass sheet was etched
one sided with an etch area of a couple of square inches. Afterward the
solution was quite hot and bubbling like soda pop on the stove. I put it
in a cold water bath to cool it down, but I have to wonder - is there the
possibility of a runaway reaction and what is the result?

Oh, and I'm sure this is common knowledge to the rest of you, but on
say, a 1 oz and 2 oz board, what are the copper thicknesses?

Thanks,
-Gary

--- In Homebrew_PCBs@yahoogroups.com, garydeal <garydeal@...> wrote:

>
>
> This afternoon I finally got around to mixing up a small batch

of

> the 1/3 HCl + 2/3 H2O2. I've read the positive reviews on that recipe
> here, but was really surprised/impressed at the results.

What strength of HCL and H2O2 did you use? I went shopping for Muratic
acid and found some at 37%, the H2O2 was 12% (listes as "40" on the
side of the bottle) from my local Salon supply store. Are these stong
enough to etch PCB's or should I look for stronger stuff?

Dave Miller

--- In Homebrew_PCBs@yahoogroups.com, garydeal <garydeal@...> wrote:

>
> Oh, and I'm sure this is common knowledge to the rest of you,

but on

> say, a 1 oz and 2 oz board, what are the copper thicknesses?
>
> Thanks,
> -Gary
>

Per IPC-4562

1/2 oz board has a copper thickness of 17.1 um, or 0.68 mils
3/4 oz board has a copper thickness of 25.7 um, or 1.01 mils
1 oz board has a copper thickness of 34.3 um, or 1.35 mils
2 oz board has a copper thickness of 68.6 um, or 2.70 mils
3 oz board has a copper thickness of 102.9 um, or 4.05 mils

Thickness (mils) = 1.35 x Area Wt (oz/ftsquared)
1 oz = the weight of copper spread over 1 sqare foot.

On Mon, 06 Mar 2006 04:57:08 +0100, garydeal <garydeal@...> wrote:

> is there the
>
> possibility of a runaway reaction and what is the result?

yes, and the result is possible injury or death if you have enough etchant.

You have a WAY too strong mixture!!

ST

On Mon, 06 Mar 2006 13:18:32 +0100, idaho_huckleberry <dmiller45@...>
wrote:

> What strength of HCL and H2O2 did you use? I went shopping for Muratic
>
> acid and found some at 37%, the H2O2 was 12% (listes as "40" on the
>
> side of the bottle) from my local Salon supply store. Are these stong
>
> enough to etch PCB's or should I look for stronger stuff?
>
>
> Dave Miller

the H2O2 is a bit weak, so will add more water, but it should work fine.
You can freeze-concentrate H2O2, but i don't think it's needed.

ST

--- In Homebrew_PCBs@yahoogroups.com, "idaho_huckleberry"
<dmiller45@...> wrote:

>
> What strength of HCL and H2O2 did you use? I went shopping for

Muratic

> acid and found some at 37%, the H2O2 was 12% (listes as "40" on the
> side of the bottle) from my local Salon supply store. Are these

stong

> enough to etch PCB's or should I look for stronger stuff?
>
> Dave Miller
>

You may want to check the 'Files' section of the group. There are a
number of very good articles posted there which have the details on
the acid etching process.


Regards, Bob

--- In Homebrew_PCBs@yahoogroups.com, garydeal <garydeal@...> wrote:

>
>
> This afternoon I finally got around to mixing up a small batch
>of
> the 1/3 HCl + 2/3 H2O2. I've read the positive reviews on that
>recipe
> here, but was really surprised/impressed at the results.
> My usual initial test is to cut a small strip of .005" brass
>and
> wave the end around in the solution, and it dissolved in record
>time. So,
> I set up a sheet with some photoresist (laminated dry-film), burned
>my
> favorite test file into the resist, developed it and popped it into
>the
> beaker. I hesitate to say that it took minutes to etch, it would
>make
> more sense to describe it as seconds. Since the test file has two
>parts
> panels, I dropped the second one in and it was nicely finished in
>short
> order. The guy that craves these parts is going to be really
>pleased, as
> am I.
>
> Question:
> The solution total was about 225 ml, and the brass sheet was
>etched
> one sided with an etch area of a couple of square inches. Afterward
>the
> solution was quite hot and bubbling like soda pop on the stove. I
>put it
> in a cold water bath to cool it down, but I have to wonder - is
>there the
> possibility of a runaway reaction and what is the result?
>
> Oh, and I'm sure this is common knowledge to the rest of you,
>but on
> say, a 1 oz and 2 oz board, what are the copper thicknesses?
>
> Thanks,
> -Gary
>

Your mixture is far too strong, you need to add more water (add acid
to water, not water to acid, though with regular muriatic the danger
isn't nearly as bad as adding water to lab grade sulfuric acid). The
40 volume H2O2 adds some water, but not enough, it seems. You don't
want the stuff etching so fast that you can't even get it out in time,
plus the fumes, heat, etc, might melt the container it's in.

Also, you want a bucket with a /lot/ of baking soda dissolved in it to
neutralize the etchant. During my one trial run with this process, I
discovered that sharpies and other permanent markers are useless as a
resist with this process, so you'd need to touch up with tough paint
on a fine brush. I'm sticking with FeCl3 so that if I /have/ an
accident I won't burn myself instantly.

--- In Homebrew_PCBs@yahoogroups.com, garydeal <garydeal@...> wrote:

>
>
> This afternoon I finally got around to mixing up a small batch of
> the 1/3 HCl + 2/3 H2O2. I've read the positive reviews on that recipe
> here, but was really surprised/impressed at the results.

>
> Question:
> The solution total was about 225 ml, and the brass sheet was

etched

> one sided with an etch area of a couple of square inches. Afterward the
> solution was quite hot and bubbling like soda pop on the stove. I

put it

> in a cold water bath to cool it down, but I have to wonder - is

there the

> possibility of a runaway reaction and what is the result?
>
>

If you are going to use the 1/3 acid 2/3 peroxide use the 3% medicinal
grade peroxide you get at the drug store. The hcl is common pool acid
sold everywhere it is about 33-37% hcl. I add 2/3 cup of peroxide to a
plastic container dry the cup, add 1/3 cup acid. This is best done
outdoors as some fumes may be given off as the acid is added. After
all the acid is added the fuming if any will stop and it may be moved
indoors. (carefully, it is quite acidic) This makes one cup of etchant
(about 225 ml) and is for immediate use. It will etch about a 6x9inch
board with good results. Maybe more, this is as big as I have done at
one time. Once it sits for a hour or so the peroxide will bubble out
and it will not etch anymore. At that point I flush it down the drain
with plenty of water. If you are doing a lot of etching you may want
to go the full fledged cupric etching solution which may be
regenerated and used over and over.

Gary,

You might want to avoid etching anything but PCB
in your main etch bath. Make up a seperate little tank
for playing with brass or anything else.

Brass is 30% zinc on average; and zinc is highly reactive.
It makes a great catalyst for decomposing H2O2. I can
imagine many different baths that it wouldn't be good for...<g>

Also, wasn't the "original" formula for this etch-bath
specified for -2- percent H2O2 ??

Your out of control exothermic reaction sounds like too
much H2O2 to me...

good luck, and please report back here how you solve
each issue!
--
============================
Please do NOT add or "subscribe" my name to ANY lists/databases.

I'm glad that you guys are clear about using 2% H202. I would have
thought more is better too. I finally have some use for that gallon of
32% HCL in the garage.

Mike

--- In Homebrew_PCBs@yahoogroups.com, "fenrir_co" <fenrir@...> wrote:
>
> --- In Homebrew_PCBs@yahoogroups.com, garydeal <garydeal@> wrote:
> >
> >
> > This afternoon I finally got around to mixing up a small batch
> >of
> > the 1/3 HCl + 2/3 H2O2. I've read the positive reviews on that
> >recipe
> > here, but was really surprised/impressed at the results.
> > My usual initial test is to cut a small strip of .005" brass
> >and
> > wave the end around in the solution, and it dissolved in record
> >time. So,
> > I set up a sheet with some photoresist (laminated dry-film), burned
> >my
> > favorite test file into the resist, developed it and popped it into
> >the
> > beaker. I hesitate to say that it took minutes to etch, it would
> >make
> > more sense to describe it as seconds. Since the test file has two
> >parts
> > panels, I dropped the second one in and it was nicely finished in
> >short
> > order. The guy that craves these parts is going to be really
> >pleased, as
> > am I.
> >
> > Question:
> > The solution total was about 225 ml, and the brass sheet was
> >etched
> > one sided with an etch area of a couple of square inches. Afterward
> >the
> > solution was quite hot and bubbling like soda pop on the stove. I
> >put it
> > in a cold water bath to cool it down, but I have to wonder - is
> >there the
> > possibility of a runaway reaction and what is the result?
> >
> > Oh, and I'm sure this is common knowledge to the rest of you,
> >but on
> > say, a 1 oz and 2 oz board, what are the copper thicknesses?
> >
> > Thanks,
> > -Gary
> >
>
> Your mixture is far too strong, you need to add more water (add acid
> to water, not water to acid, though with regular muriatic the danger
> isn't nearly as bad as adding water to lab grade sulfuric acid). The
> 40 volume H2O2 adds some water, but not enough, it seems. You don't
> want the stuff etching so fast that you can't even get it out in time,
> plus the fumes, heat, etc, might melt the container it's in.
>
> Also, you want a bucket with a /lot/ of baking soda dissolved in it to
> neutralize the etchant. During my one trial run with this process, I
> discovered that sharpies and other permanent markers are useless as a
> resist with this process, so you'd need to touch up with tough paint
> on a fine brush. I'm sticking with FeCl3 so that if I /have/ an
> accident I won't burn myself instantly.
>

Hey, thanks for all the comments!
Lots of interesting stuff, but I'll just post the trimmed-down
version

>yes, and the result is possible injury or death if you have enough
>etchant.
>
>You have a WAY too strong mixture!!

Could you perhaps be a bit more specific regarding the possible
injury and death? Those risks are a typical part of my daily life and
it's the specific details that allow me to take appropriate precautions.
Are there other potential results beyond boilover and a corrosive mess?
Like say, explosive disassociation of the hydrogen, chlorine, and oxygen
with subsequent ignition of same (ultra-bad news)?
It was a total of 225 ml, 1/3 ~37% HCl, 2/3 "40 volume" (12%?)
peroxide. When fresh and cool, it *was* extremely effective, but not
something I'd recommend to the inexperienced. Please see below.

>If you are going to use the 1/3 acid 2/3 peroxide use the 3% medicinal
>grade peroxide you get at the drug store. The hcl is common pool acid
>sold everywhere it is about 33-37% hcl. I add 2/3 cup of peroxide to a
>plastic container dry the cup, add 1/3 cup acid. This is best done
>outdoors as some fumes may be given off as the acid is added. After
>all the acid is added the fuming if any will stop and it may be moved
>indoors. (carefully, it is quite acidic)

Thank You. Is that simple note in the files section?
All newbies please follow the simple procedure above. Be really
careful with the acid, buy and wear goggles and gloves, and keep a gallon
jug of distilled water (with the seals opened) near enough to grab with
your eyes closed. Store the acid secured against access by children and
idiots and preferably away from anything of value (HCl makes nasty fumes,
sometimes even through a closed container). Add baking soda in very small
amounts until the etchant no longer bubbles before sending down the
drain. Do not attempt to replicate my own activities without serious
industrial safety training and equipment, and remember that it's
sometimes better to be lucky than good.
Oh, and aside from the safety recommendations, don't take me or my
posts seriously enough to warrant flaming. For me, much of the time the
process itself is the project.

Thanks again,
-Gary

On Wed, 08 Mar 2006 08:04:11 +0100, garydeal <garydeal@...> wrote:

>> yes, and the result is possible injury or death if you have enough
>
>> etchant.
>
>>
>
>> You have a WAY too strong mixture!!
>
>
> Could you perhaps be a bit more specific regarding the possible
>
> injury and death? Those risks are a typical part of my daily life and
>
> it's the specific details that allow me to take appropriate precautions.
>
> Are there other potential results beyond boilover and a corrosive mess?
>
> Like say, explosive disassociation of the hydrogen, chlorine, and oxygen
>
> with subsequent ignition of same (ultra-bad news)?

I don't have specifics, but rumors say industrial quantities have "gone
through walls" and even killed people.

As you say the danger is probably a runaway reaction with the container
failing or spilling over due to many bubbles and the creation of HCl and
chlorine fumes. Remember HCl boils at only like 50C or so. Also, gaseous
chlorine is sometimes used for industrial regeneration which adds danger
too.

ST

--- In Homebrew_PCBs@yahoogroups.com, Richard <metal@...> wrote:

>
>
> Gary,
>
> You might want to avoid etching anything but PCB
> in your main etch bath. Make up a seperate little tank
> for playing with brass or anything else.
>
> Brass is 30% zinc on average; and zinc is highly reactive.
> It makes a great catalyst for decomposing H2O2. I can
> imagine many different baths that it wouldn't be good for...<g>
>

Hello,
I am going to be etching some brass sheets (0.10" thick) for a
project I am working on. I will be etching them to 1/2 thickness.
Would you recommend the peroxide/muriatic solution for this, or
would something else be better/safer?

Also, would I be able to regenerate this mix with a bubbler? I will
be using the mixture as listed in the files section.

Thanks!

>I am going to be etching some brass sheets (0.10" thick) for a
>project I am working on. I will be etching them to 1/2 thickness.
>Would you recommend the peroxide/muriatic solution for this, or
>would something else be better/safer?

Greg,
I was waiting to see if someone else with more experience would
answer, but I think the 1/3 (37%) HCl and 2/3 pharmacy-type (~3%)
peroxide will probably work for you. I'll be trying to get to trying that
one this weekend - my other mix was a bit *too* effective.

>Also, would I be able to regenerate this mix with a bubbler? I will
>be using the mixture as listed in the files section.

There's recently been a lot of posts on this formula, it's changes
through use, and methods of sprucing it up with the addition of small
amounts of acid or peroxide. I don't know about the bubbler (adding
oxygen?). Since I'm doing rather small quantities I'll probably just
neutralize and mix fresh when I think it's dying.

Please post your results and evaluations if possible.
-Gary

I think the main question here is not about the CuCl stuff, we understand
that well, but for copper.
What happens with brass i wouldn't know.

The bubbling normally adds oxygen like H2O2 does, but again, i do not know
what happenss with the added zinc.

ST

On Fri, 10 Mar 2006 20:20:00 +0100, garydeal <garydeal@...> wrote:

>> I am going to be etching some brass sheets (0.10" thick) for a
>
>> project I am working on. I will be etching them to 1/2 thickness.
>
>> Would you recommend the peroxide/muriatic solution for this, or
>
>> would something else be better/safer?
>
>
> Greg,
>
> I was waiting to see if someone else with more experience would
>
> answer, but I think the 1/3 (37%) HCl and 2/3 pharmacy-type (~3%)
>
> peroxide will probably work for you. I'll be trying to get to trying that
>
> one this weekend - my other mix was a bit *too* effective.
>
>
>> Also, would I be able to regenerate this mix with a bubbler? I will
>
>> be using the mixture as listed in the files section.
>
>
> There's recently been a lot of posts on this formula, it's changes
>
> through use, and methods of sprucing it up with the addition of small
>
> amounts of acid or peroxide. I don't know about the bubbler (adding
>
> oxygen?). Since I'm doing rather small quantities I'll probably just
>
> neutralize and mix fresh when I think it's dying.
>
>
> Please post your results and evaluations if possible.
>
> -Gary

--- In Homebrew_PCBs@yahoogroups.com, "Stefan Trethan"
<stefan_trethan@...> wrote:

>
> I think the main question here is not about the CuCl stuff, we

understand

> that well, but for copper.
> What happens with brass i wouldn't know.
>
> The bubbling normally adds oxygen like H2O2 does, but again, i do

not know

> what happenss with the added zinc.
>
> ST

I just want to make sure it would be safe to introduce brass to the
mixture without any dangerous changes in composition.

I will also be doing small etchings also, but if it works out OK, I
may end up selling some of my etchings, and therefore would like
to "renew" the mixture using the bubbler method.

Plus, I am used to the bubbler in the etchant to help etching
speeds, along with an aquairum heater, from other etching
techniques.

Also, i wanted to make sure it would be safe to store this mixture
in a Rubbermaid container, or if the mixture would create enough
gasses to blow the lid off, if brass is introduced. A previous post
mentioned that brass etched in this mixture may create too much
bubbling.

Greg

Using bubbling for regeneration is a lengthy process, also producing
plenty of air containing particles of etchant (corrosive). I personally do
not see much reason to use it if H2O2 is available (in higher
concentrations, say 30%).
If your etchant needs regenerating during a etch you can simply add some
H2O2, with bubbling you would have to at least pause the etch and
regenerate for several hours. This means you need to keep a much larger
etching bath volume.

I do not know what will happen with the brass. I'm very bad at chemistry.

ST


On Mon, 13 Mar 2006 22:11:43 +0100, Greg Codori <greg_codori@...>
wrote:

> I just want to make sure it would be safe to introduce brass to the
>
> mixture without any dangerous changes in composition.
>
>
> I will also be doing small etchings also, but if it works out OK, I
>
> may end up selling some of my etchings, and therefore would like
>
> to "renew" the mixture using the bubbler method.
>
>
> Plus, I am used to the bubbler in the etchant to help etching
>
> speeds, along with an aquairum heater, from other etching
>
> techniques.
>
>
> Also, i wanted to make sure it would be safe to store this mixture
>
> in a Rubbermaid container, or if the mixture would create enough
>
> gasses to blow the lid off, if brass is introduced. A previous post
>
> mentioned that brass etched in this mixture may create too much
>
> bubbling.
>
>
> Greg