Homebrew PCBs

The BBC just had a piece about the trial of those would-be bombers.

<http://news.bbc.co.uk/1/hi/uk/6274299.stm>
<http://news.bbc.co.uk/1/hi/uk/6274299.stm>

It may still be possible to buy small quantities of H2O2 for PCB etching  
at those shops, especially if one is not afraid of questions and some  
interest.

ST

From the article:
"using a mix of the liquid hydrogen peroxide, chapatti flour, acetone
and acid."

This doesn't make sense, as flour is not used in the manufacture of
acetone peroxide.  Sometimes acetone peroxide or benzoy peroxide is
added to flour in small amounts in order to bleach the flour, ergo the
bleached flour you buy at the store.


--- In Homebrew_PCBs@yahoogroups.com, "Stefan Trethan"
<stefan_trethan@...> wrote:
>
> 
> The BBC just had a piece about the trial of those would-be bombers.
> 
> <http://news.bbc.co.uk/1/hi/uk/6274299.stm>
> <http://news.bbc.co.uk/1/hi/uk/6274299.stm>
> 
> It may still be possible to buy small quantities of H2O2 for PCB
etching  

> at those shops, especially if one is not afraid of questions and some  
> interest.
> 
> ST
>

On 21/01/07, bobysgotguns <bdt@...> wrote:
>
>
>
>
>
>
> From the article:
>  "using a mix of the liquid hydrogen peroxide, chapatti flour, acetone
>  and acid."
>
>  This doesn't make sense, as flour is not used in the manufacture of
>  acetone peroxide.

Maybe it was to 'retard' it or make it slower to explode ? safer to transport ?

I know nothing of bomb making, except the people doing it are screwing
it up for homebrew pcb as more and more restrictions are imposed.

Lez

--- In Homebrew_PCBs@yahoogroups.com, Lez <lez.briddon@...> wrote:
> 
> I know nothing of bomb making, except the people doing it are screwing
> it up for homebrew pcb as more and more restrictions are imposed.
> 
> Lez
>

I wouldn't worry too much about H2O2 availibility. The pcb makers are a 
very small minority, then the authorities start setting the availibilty 
rules, they will have to listen to a very loud bunch of housewives.!

Let's be realistic, there is a difference betwenn buying a single liter 
and 200.

For etching you really don't need the 30% H2O2, it results in a very 
violernt reaction. I found out the hard way.The standard 3% is just 
about the correct diluted strength. Yes, a stroneger versioon is great 
for regeneration, but the stuff is so cheap anyways.

<yc

----- Original Message ----- 

From: "bobysgotguns" <bdt@...>
To: <Homebrew_PCBs@yahoogroups.com>
Sent: Sunday, January 21, 2007 9:42 AM
Subject: [Homebrew_PCBs] Re: H2O2 in the UK


> From the article:
> "using a mix of the liquid hydrogen peroxide, chapatti flour, acetone
> and acid."
>
> This doesn't make sense, as flour is not used in the manufacture of
> acetone peroxide.  Sometimes acetone peroxide or benzoy peroxide is
> added to flour in small amounts in order to bleach the flour, ergo the
> bleached flour you buy at the store.

Perhaps they wanted to make sure they could cook some chapattis when they 
reached paradise. 8-)

Leon
--
Leon Heller
Amateur radio call-sign G1HSM
Yaesu FT-817ND transceiver
Suzuki SV1000S motorcycle
leon355@...
http://www.geocities.com/leon_heller

On Sun, 21 Jan 2007 11:39:07 +0100, mycroft2152 <mycroft2152y@...>  
wrote:

>
> For etching you really don't need the 30% H2O2, it results in a very
> violernt reaction. I found out the hard way.The standard 3% is just
> about the correct diluted strength. Yes, a stroneger versioon is great
> for regeneration, but the stuff is so cheap anyways.


Yes, but the added water would grow your etchant too much.
I think for CuCl you _do_ need the stronger stuff.

Maybe one can freeze concentrate the 3% stuff, i never tried, and it would  
surely be safer and cheaper to just buy the 30% version.

ST

On Sun, 21 Jan 2007 11:45:13 +0100, Leon <leon355@...> wrote:

> Perhaps they wanted to make sure they could cook some chapattis when they
> reached paradise. 8-)
> Leon


Probably thought it would go well with the raisins, but we are getting off  
topic.

ST

I've given up now on the fecl alternatives, will be having a drive to
maplins this week to buy some more, at least when its tired you can
use it to dye denim a nice golden brown........

At 4:16 am ((PST)), Sat Jan 20, 2007 Stefan Trethan wrote:

>The BBC just had a piece about the trial of those would-be bombers.
>[snip]

Moral: remember to ask for a discount on quantity ;-)

>It may still be possible to buy small quantities of H2O2 for PCB etching
>at those shops, especially if one is not afraid of questions and some
>interest.

On Friday last I went into our local chemists and checked with the
pharmacist whether she stocked hydrochloric acid (which I had
bought from her some long time ago) and hydrogen peroxide.

The answer was yes in both cases, though she called the HCl
"Spirits of Salts" - which is how it is labelled. The H2O2 was
stocked in 2 strengths: 6% (20vol) & 9% (30vol). A bit weak
for regenerating CuCl, but perfectly adequate for HCl-H2O2
etching.

I wasn't asked "Would you like acetone with that?" ;-)

I did this research in delayed response to someone's
claims of not being able to buy chemicals in the UK,
which he has repeated despite my reply pointing out
that one can (and yes, IPA is still available from Maplin,
too, shelf stock last time I looked).

Might I also urge people to identify the active ingredient
and its _concentration_. Most of us easily can look up the
etymology of "muriatic acid" and such like common names,
but we can't read the label on _your_ bottle of chemical to
know the concentration - you have to tell us.

[A recent recommendation to prepare PCB with a 30sec
pre-etch  in HCl-H2O2, which could have stripped most
of the copper at the strengths some have available. ;-)
Please remember that people using your advice may not
have the benefit of your experience.

Another post identified soda ash with washing soda -
although both are sodium carbonate, IIIRC those pretty
crystals of washing soda contain ten molecules of water
of  crystallization - so a 1% solution of washing soda
is a lot weaker than a 1% solution of sodium carbonate.]

Whereas hydrochloric acid seems usually to be supplied in
the mid-30% range near or at its maximum concentration,
H2O2 is usually diluted. Pharmacy shelf strength as a
general bleach, disinfectant and and sterilizer is 3, 6 or 9%,
beauty parlour strength seems to be around 30% and
anything more is industrial going on rocket fuel strength
  - and could incinerate you.

Also remember that H2O2 is de-stabilized by metal ions
and other particulate matter, so (a) it isn't a good idea
to store it in another bottle than it was supplied in and
(b) don't expect to part-used HCl-H2O2 to have any
shelf life at all.

On Sun, 21 Jan 2007 16:34:09 +0100, Len Warner <novost@...> wrote:

>
> Also remember that H2O2 is de-stabilized by metal ions
> and other particulate matter, so (a) it isn't a good idea
> to store it in another bottle than it was supplied in

Well, it makes PE bottles brittle from the inside. I store it in glass  
now. Should be very clean though.
There are special caps with safety pressure relief, although i was told by  
the shop they are not required for H2O2.

I'm thinking to get some medical luer-lock plastic valves and install one  
to a bottle cap, for easier dispensing.

> and
> (b) don't expect to part-used HCl-H2O2 to have any
> shelf life at all.


That's true.

ST

I always liked the post where the pcb maker was going to "distill' 
the H2O2 to make it stronger.

;)

Myc
--- In Homebrew_PCBs@yahoogroups.com, Len Warner <novost@...> wrote:
>
> At 4:16 am ((PST)), Sat Jan 20, 2007 Stefan Trethan wrote:
> 
> >The BBC just had a piece about the trial of those would-be bombers.
> >[snip]
> 
> Moral: remember to ask for a discount on quantity ;-)
> 
> >It may still be possible to buy small quantities of H2O2 for PCB 
etching
> >at those shops, especially if one is not afraid of questions and 
some

> >interest.
> 
> On Friday last I went into our local chemists and checked with the
> pharmacist whether she stocked hydrochloric acid (which I had
> bought from her some long time ago) and hydrogen peroxide.
> 
> The answer was yes in both cases, though she called the HCl
> "Spirits of Salts" - which is how it is labelled. The H2O2 was
> stocked in 2 strengths: 6% (20vol) & 9% (30vol). A bit weak
> for regenerating CuCl, but perfectly adequate for HCl-H2O2
> etching.
> 
> I wasn't asked "Would you like acetone with that?" ;-)
> 
> I did this research in delayed response to someone's
> claims of not being able to buy chemicals in the UK,
> which he has repeated despite my reply pointing out
> that one can (and yes, IPA is still available from Maplin,
> too, shelf stock last time I looked).
> 
> Might I also urge people to identify the active ingredient
> and its _concentration_. Most of us easily can look up the
> etymology of "muriatic acid" and such like common names,
> but we can't read the label on _your_ bottle of chemical to
> know the concentration - you have to tell us.
> 
> [A recent recommendation to prepare PCB with a 30sec
> pre-etch  in HCl-H2O2, which could have stripped most
> of the copper at the strengths some have available. ;-)
> Please remember that people using your advice may not
> have the benefit of your experience.
> 
> Another post identified soda ash with washing soda -
> although both are sodium carbonate, IIIRC those pretty
> crystals of washing soda contain ten molecules of water
> of  crystallization - so a 1% solution of washing soda
> is a lot weaker than a 1% solution of sodium carbonate.]
> 
> Whereas hydrochloric acid seems usually to be supplied in
> the mid-30% range near or at its maximum concentration,
> H2O2 is usually diluted. Pharmacy shelf strength as a
> general bleach, disinfectant and and sterilizer is 3, 6 or 9%,
> beauty parlour strength seems to be around 30% and
> anything more is industrial going on rocket fuel strength
>   - and could incinerate you.
> 
> Also remember that H2O2 is de-stabilized by metal ions
> and other particulate matter, so (a) it isn't a good idea
> to store it in another bottle than it was supplied in and
> (b) don't expect to part-used HCl-H2O2 to have any
> shelf life at all.
>

On Sun, 21 Jan 2007 17:17:05 +0100, mycroft2152 <mycroft2152y@...>  
wrote:

> I always liked the post where the pcb maker was going to "distill'
> the H2O2 to make it stronger.
> ;)
> Myc


I think you can freeze concentrate it without too much trouble. Those  
interested in using it as rocket fuel know more about that, there are some  
pages about that. But i highly doubt it would be worth the effort for  
etching, even evaporating etchant to get rid of excess water would seem  
easier.
If you try anything like that you should definitely get a hydrometer to  
measure the actual H2O2 concentration.

ST

Last time I got some, I was told by the shop owner that the strongest
they are allowed to sell these days is 17%.

Les


Stefan Trethan wrote:

> Yes, but the added water would grow your etchant too much.
> I think for CuCl you _do_ need the stronger stuff.
>
> Maybe one can freeze concentrate the 3% stuff, i never tried, and it would  
> surely be safer and cheaper to just buy the 30% version.
>
> ST
>
>

At 8:21 am ((PST)) Sun Jan 21, 2007, mycroft2152 wrote:
>I always liked the post where the pcb maker was going to "distill'
>the H2O2 to make it stronger.

Possible, done industrially, but probably high
on the "Don't try this at home" list.

[I enjoyed the post on another list where the obviously nearly
clueless individual was going to use conc. H2SO4 as an
air drying agent in his H2O2 concentrating apparatus.

Conc. H2SO4 is not something I would like to add to a device
that is already capable of a BLEVE. (see Wikipedia,
AKA "Blast Leveling Everything Very Effectively")]

I've seen it said a few times: "peroxides kill chemists".

But if you must...

Pure H2O2 boils at 150degC, so distillation is possible.

However, it is increasingly unstable at elevated temperatures,
so perhaps you might think of distilling under reduced pressure.

This will work, unless you discover that the vapour can explode
spontaneously at around 70degC.

If you avoid those "gotchas", you might instead discover that
its vapour can form contact explosives with grease and other
organic materials, so you have to be very careful about what
you use for seals in your apparatus and also ensure there are
no residues of cleaning solvents inside.

Better not to try, I think.

Safer might be sparging with air. Some H2O2 will be discharged
with the exhaust air, but at least it will go safely to waste rather
than coming back to bite you. A cursory glance at tables 13 & 14
here http://www.h2o2.com/intro/properties/physical.html suggests
to me this might work quite well to beyond 30%, especially at low
temperatures, but would then be progressively more wasteful.
Apart from that, there doesn't seem to be an upper limit. You might
be able to use a cold trap to collect the vented H2O2 (and the water)
and fractional crystallization (see below) to recycle the waste H2O2
  - economical in H2O2 but expensive in energy

[This also explains this warning from Wikipedia: Hydrogen peroxide,
if spilled on clothing (or other flammable materials), will preferentially
evaporate water until the concentration reaches sufficient strength,
then clothing will spontaneously ignite. Leather generally contains
metal ions from the tanning process and will often catch fire almost
immediately.]

"Freezer distilling" (fractional crystallization and removal of the
excess water as ice) works up to a point and is probably safest.
Tables 10 & 11 http://www.h2o2.com/intro/properties/physical.html
suggest that about 25% is possible at -20degC and the maximum
is around 58% at -55degC. Actual results will be worse, depending
on how good your lab technique is for removing the ice crystals
without spoiling the cold. Perhaps someone would like to start a
cryonic centrifuge project?  ;-)

In practical terms, if you have a particularly cold domestic freezer
you might be able to convert 3% (10vol) peroxide to around 20%,
suitable for CuCl etchant regeneration. If you have easy access to
dry ice then you could use a freezing mixture with acetone or ether
http://www2.uni-siegen.de/~pci/versuche/english/v105-2.html
to approach 60% peroxide. Before you attempt this, be sure you
know how to handle it, because at this strength the whole volume
of the liquid can spontaneously decompose into hot gas - ouch!


Regards, LenW