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'[EE:] Etchant chemistry- WAS- Ferric chloride etch'
2004\09\12@233138 by Denny Esterline

picon face
Let's try this again, apologies if anyone receives it twice.

> If anyone wants to suggest an alternative to FeCl that has a decent shelf
> life and isn't too hard to dispose of, I'm open to suggestions.
>
> Later.
> --
> Phil.

In my opinion the only etchant acceptable for hobbyist work is CuCl.

There are several ways of 'starting' a batch of CuCl and some of them have
their drawbacks, but a 'mature' batch of CuCl is a great etchant.

*It's cheap.
*Materials avaialable localy almost everywhere.
*Doesn't stink. (more on that later)
*Clear enough so you can see the board being etched.
*Compatible with most etch resists- toner transfer, resist pens and
photomask.
*Unlimited shelf life - long term exposure to air regenerates it.
*The best part- infinitely renewable - you never need to dispose of it.

I started mine about a year ago using HCl and H2O2 (hydrochloric acid -
branded Muratic acid - 32% strength, and 3% medical grade hydrogen
peroxide) Both are available locally, HCl about $4 US per gallon and H2O2
less than $1 per quart. I used two parts H2O2 and one part HCl and got a
fairly aggressive etchant (about 4 minutes) and yes, it produced nasty
Chlorine fumes.

That's because the initial reaction is very different from a 'mature'
batch. When first started this way the free oxygen from the H2O2 breaks the
HCl bonds and produces water and free chlorine - thus bubbling and
stinking. i.e.

H2O2 + 2 HCl -> 2 H2O + 2 Cl

When in the presence of copper this chlorine bonds with the copper and
produces CuCl2. i.e.

H2O2 + 2 HCl + Cu -> 2 H2O + CuCl2

This is a very different reaction than what you find in a 'mature' batch of
etchant. Where there is *no* free chlorine. (thus no bubbles and no stink)

CuCl2 + Cu -> Cu2Cl2

There are a couple ways to regenerate the bath. Basically they involve
adding oxygen to break down remaining HCl in the bath. It can be done very
quickly by adding high strength (30% or higher) H2O2 or it can be done by
bubbling air through the bath. Since high strength H2O2 involves hazmat
shipping fees, and I already have a bubbler for agitation, I just leave it
running for a day or so after I use the bath. The chemistry is something
like this:

Cu2Cl2 + 2 HCl + 02 -> 2 CuCl2 + H2O

I've heard of people getting etch times of less than 30 seconds by adding
lots of high strength H2O2. While it's possible, it does get back to the
problems of having free chlorine - nasty fumes.

After *lots* of use eventually the HCl is depleted and bubbling will no
longer regenerate the etchant, at that point just adding more HCl will
solve the problem. Note: I've run about 5 square foot of 1 ounce DS board
through my gallon of etchant and haven't had to do this yet.

Some people have complained that bubbling the etchant can produce a fine
mist that attacks nearby metal, I haven't had that problem. Mostly because
I leave the lid on while bubbling and throw and old rag over the vent.

There are a few other ways of starting a batch too, though I haven't tried
them myself. Apparently CuCl powder is available in some areas. IIRC that
gets added to an acid/water solution.

Lots of links and good information can be had on the homebrew PCB group:

http://groups.yahoo.com/group/Homebrew_PCBs/

-Denny



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2004\09\13@005012 by Peter Johansson

flavicon
face
You write:

> Let's try this again, apologies if anyone receives it twice.

So far I've only received it once...

> In my opinion the only etchant acceptable for hobbyist work is CuCl.
>
> Lots of links and good information can be had on the homebrew PCB group:
>
> http://groups.yahoo.com/group/Homebrew_PCBs/

Thank you *so* much for posting this!  I haven't etched a PCB in 20
years, but I just might be etching a bunch in the next few weeks --
all 1-offs or I'd simply be using one of the low-volume commercial
shops.

The only masking system I know of is the resist-ink pen.  Can you
provide the low-down on the best way for the hobbyist to mask a board
these days?  I already own both inkjet and laser printers...

-p.
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2004\09\13@035121 by hilip Stortz

picon face
in which case you should get a much better yield using a tall thin
container rather than a shallow one as on average the free chlorine will
have to travel farther before leaving solution and have a greater chance
of reacting.  some copper wool (if such a thing exist, i'm not sure...)
or possibly even brass wool on top would likely reduce fumes.  
keeping the lid on and putting a rag over it when bubbling is an
excellent way to eliminate any mist, provided you wear gloves when
removing the rag and wash it promptly since it will have some free
etchant/acid on it.

very interesting chemistry, and interesting that it works so quickly.

for what it's worth, if you can get them to sell it to you, a beauty
supply store should have fairly concentrated hydrogen peroxide.  i
haven't tried to buy it but normally you are supposed to have a
beauticians license to buy anything from them in this state, though i
don't know how strictly enforced that is and if they might not be happy
to sell it after you convinced them you weren't dying hair with it.  i'd
think you might also be able to bubble oxygen through it (you'd need a
plastic diffuser for the gas to make small bubbles, smallparts.com has
such plastic/teflon items) particularly since air will do it.  i'd also
think that a fine diffuser would make the air method work faster with
less evaporation (and smaller bubbles should produce less mist).  it
might or might not be worth the expense and trouble.

now, if any one can come up with a way to do real through hole plating,
that would be exciting (in which case you normally drill the board
first, convince some fine metal to line the holes, and then electroplate
copper into the holes and the board surface, which is why board houses
start with 1/2 oz copper to make 1 oz copper boards, and then etch it).

i'd just love to be able to make real through hole boards for
prototyping and i have the space to do it once i get the garage
organized (my 4' by 8' table with pvc on the top would be perfect if i
got water out there, which i was already planing to do).

it's fantastic that it's a continuous cycle without waste! (other than
chlorine, which is already released from pools and when people use
bleach and not yet very regulated, i don't know if it should be or not,
probably not for small volumes)  now i see why many board houses do it
that way.

Denny Esterline wrote:
-------
> I started mine about a year ago using HCl and H2O2 (hydrochloric acid -
> branded Muratic acid - 32% strength, and 3% medical grade hydrogen
> peroxide) Both are available locally, HCl about $4 US per gallon and H2O2
> less than $1 per quart. I used two parts H2O2 and one part HCl and got a
> fairly aggressive etchant (about 4 minutes) and yes, it produced nasty
> Chlorine fumes.
-------

-- Philip Stortz--"In Germany they came first for the Communists, and I
didn't speak up because I wasn't a Communist. Then they came for the Jews, and I didn't speak up because I wasn't a
Jew. Then they came for the trade unionists, and I didn't speak up because I
wasn't a trade unionist. Then they came for the Catholics, and I didn't speak up because I was a
Protestant. Then they came for me, and by that time no one was left to speak up."
-- Martin Niemöller, 1892-1984 (German Lutheran Pastor), on the Nazi
Holocaust, Congressional Record 14th October 1968 p31636.

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2004\09\13@045305 by hilip Stortz

picon face
i have to get my stuff set up, but i do have a uv exposure frame.  one
method i love is to plot the layout on mylar, reversed so you can put
the ink side down on sensitized boards (you could do it non-reversed
with the ink away from the board if you didn't need as much resolution,
probably).  they make great mask for a few exposures (i don't know how
well they'd hold up after dozens of uses).  interestingly red plotter
ink works as good as black.  last time i did this i used black for one
side and red for the other to help keep them straight.  of course this
assumes you have access to a plotter.  at the time i was using a
mechanical cad program but many board layout programs can do the same
thing.  i've always liked the photolithography based methods.  the mylar
is cheap, and if you don't have a plotter some art supply and copying
stores will make plots for you.  the common pen widths work out nicely
for 10 mill traces and larger, and as i recall the smaller size pens are
around 5-6 mills if you really needed that and had a really good coating
on the boards.  if you have a plotter, it's also nice and quick.  there
also was at one time a company selling etch resist pens for plotters so
you could plot directly onto your board.  i never tried it so i can't
say how well it works or doesn't work.  
i have 2 surplus plotters now, an hp i got on ebay and one i don't
remember the brand of off hand that i haven't even tried (got it free!)
but if it works i suspect it's very fast as it moves all the pens all
the time and just pushes down on the own that's marking!  it looks
pretty fast.  i'm still not sure exactly where i'll put that plotter (c
or d size i think).  the only thing to remember is to always cap the
pens if you won't be using it the next day, i usually capped them at the
end of every day and only needed the solvent to unclog the pens on the
finer ones which are always a pain!  of course you need the pens meant
for mylar and the plotter mylar that's textured on one side (the side
you mark on).

an exposure frame/box really isn't that hard to make.  just remember to
use the right goggles if it isn't completely light tight, again eyes are
expensive.  you can still get the screw in uv bulbs that you just put in
a cheap clamp on fixture a couple of feet above an exposure frame, i've
made one from a piece of glass and some wood before, just put a couple
of layers of electrical tape on the glass edges so you don't lose any
fingers (and if you go to a glass shop you'll see the older employees
are usually short parts of fingers).  a 12" square piece of window glass
is fairly inexpensive.  get "single" strength, as it does absorb about
10% of the uv, double strength would probably absorb about 20% though
that would still be ok if you really wanted the thicker glass.

it's probably also worth while to use distilled water for mixing all of
your chemicals, minerals in tap water can really complicate things,
especially if you are using tin plating (nearly essential particularly
for surface mount or you have to clean the board immediately before
soldering).  do a google search for some of the suppliers, unfortunately
kepro is out of business and another company has sort of continued their
line.  i'd be curious to know why kepro went out of business though,
they were one of the most popular.

Peter Johansson wrote:
------
>
> The only masking system I know of is the resist-ink pen.  Can you
> provide the low-down on the best way for the hobbyist to mask a board
> these days?  I already own both inkjet and laser printers...
--------

-- Philip Stortz--"In Germany they came first for the Communists, and I
didn't speak up because I wasn't a Communist. Then they came for the Jews, and I didn't speak up because I wasn't a
Jew. Then they came for the trade unionists, and I didn't speak up because I
wasn't a trade unionist. Then they came for the Catholics, and I didn't speak up because I was a
Protestant. Then they came for me, and by that time no one was left to speak up."
-- Martin Niemöller, 1892-1984 (German Lutheran Pastor), on the Nazi
Holocaust, Congressional Record 14th October 1968 p31636.

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2004\09\13@072326 by Byron A Jeff

face picon face
On Mon, Sep 13, 2004 at 12:50:10AM -0400, Peter Johansson wrote:
{Quote hidden}

You're going to get a lot of different opinions. Everything from direct
resist application using a plotter to just sending the job out to a
board house to do. For my money developing with positive preapplied
photoresist boards is the most consistent technique for one offs. The
whole process is described here:

http://www.electricstuff.co.uk/pcbs.html

The short of it is:

1) Print artwork on a transparancy with your laser.
2) Affix to the board (in low light) and expose to UV.
3) Develop with a developer.
4) Etch. Note the CuCl discussion already.
5) Drill and done.

Also your artwork is still available for making other boards. Finally
since the board is the expensive part and the transparancy media is
cheap you can afford to mess up the artwork, and only use the exact
part of the board that you need.

Hope this helps,

BAJ
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2004\09\13@104909 by Support - KF4HAZ

flavicon
face
For a the lowest cost software (free) I use MSpaint.
I make my drawings "E-up Positive" (as viewed from top of pcb)
To make the resolution easier to get fine detail I work at 5x scale.
This works out to 480 dpi, then I scale it back to by loading it into
either,
MSphoto or Kodak imaging and setting it to 480 dpi (paint uses 96dpi),
I then save it as a tiff @ 480dpi and ftp it to LithoPlate&Negative
67.32.155.204
They Print a Litho on photographic film,
a true litho will block sunlight in the black areas.
They charge ~$30 for a 12"x18" board (which may contain several pcb layouts)

KF4HAZ - Lonnie

----- From: "Peter Johansson" <peter@

{Quote hidden}

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2004\09\13@110243 by William Chops Westfield

face picon face
On Sep 13, 2004, at 12:53 AM, Philip Stortz wrote:

>
> for what it's worth, if you can get them to sell it to you, a beauty
> supply store should have fairly concentrated hydrogen peroxide.

For CuCl2 etchant, you don't need concentrated H2O2.  H2O2 is just one
way of getting your original solution, or replenishing used etchant.

Acid (HCl or H2SO4) and peroxide is an altogether different etchant,
apparently known in lab (hmm.  And semiconductor) circles as "piranha."
Very aggressive and somewhat nasty; probably the cause of the really
fast etch times some people are reporting for CuCl2; I didn't get the
impression that CuCl2 on its own was all that zippy.

Are y'all sure you're seeing chlorine evolved?  HCl fumes are nasty
in their own right, and I've never seen anything that was particularly
obviously chlorine-colored.  Note that chlorine is moderately soluble
in water...

BillW

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2004\09\13@111436 by Denny Esterline

picon face
> in which case you should get a much better yield using a tall thin
> container rather than a shallow one as on average the free chlorine will
> have to travel farther before leaving solution and have a greater chance
> of reacting.  some copper wool (if such a thing exist, i'm not sure...)
> or possibly even brass wool on top would likely reduce fumes.

In practicality 'yield' isn't realy a concern. None of the chemistry here
is expensive enough or toxic enough for that to be a concern. I'd also be
very careful about the brass, this etchant will etch most anything -
including stainless steel - using brass or other metals will seriously
complicate the regeneration proccess.

> keeping the lid on and putting a rag over it when bubbling is an
> excellent way to eliminate any mist, provided you wear gloves when
> removing the rag and wash it promptly since it will have some free
> etchant/acid on it.

Of course, standard safety protocols should be followed - gloves, goggles
ect, an apron whouldn't be a bad idea... :o)

> very interesting chemistry, and interesting that it works so quickly.

Standard etch times for a batch of 'mature' etchant that's been regenerated
the day before runs about 8 - 11 minutes, with no chlorine gas production.
Adding excess H2O2 will produce offensive chlorine, but can etch in less
than 30 seconds. - I don't reccomend it.

> for what it's worth, if you can get them to sell it to you, a beauty
> supply store should have fairly concentrated hydrogen peroxide.  i
> haven't tried to buy it but normally you are supposed to have a
> beauticians license to buy anything from them in this state, though i
> don't know how strictly enforced that is and if they might not be happy
> to sell it after you convinced them you weren't dying hair with it.  i'd

A larger 'chain' store I tried only had prepackaged 'products'. Though I'm
sure some of them contained peroxide, purity and strength were
indeterminite and I just chose to avoid the complication. There's a good
chance other stores might have it though, I quit looking.

> think you might also be able to bubble oxygen through it (you'd need a
> plastic diffuser for the gas to make small bubbles, smallparts.com has
> such plastic/teflon items) particularly since air will do it.  i'd also
> think that a fine diffuser would make the air method work faster with
> less evaporation (and smaller bubbles should produce less mist).  it
> might or might not be worth the expense and trouble.

Air works alright, so I don't see a benifit to going to strait oxygen. I
use an aquarium pump, silicone hose and plastic difuser from my local
walmart. A rubbermaid cerial keeper works fine for the tank, total
cost -about $25.

> now, if any one can come up with a way to do real through hole plating,
> that would be exciting (in which case you normally drill the board
> first, convince some fine metal to line the holes, and then electroplate
> copper into the holes and the board surface, which is why board houses
> start with 1/2 oz copper to make 1 oz copper boards, and then etch it).

Check out the yahoo group I mentioned earlier, there's a guy on there that
does homebrew through hole plating. But I think his setup is rather
extensive.

{Quote hidden}

Maybe I mistyped somewhere, but the etchant should *not* release chlorine
during normal operation. The chlorine should be combined with the copper in
the bath. It only escapes when there's an excess of free oxygen (impossible
to do with an air bubbler) and no copper available. A condition normally
only seen when starting a CuCl in this way.

It's also interesting to note that many board houses do not use this
etchant. Some processes use tin plating as an etch resist, CuCl will
happily etch the tin too.

-Denny


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2004\09\13@120323 by Philip Pemberton

face picon face
In message <003001c49942$bce48280$0d401545@whythis>
         "Denny Esterline" <spam_OUTfirmwareTakeThisOuTspamtds.net> wrote:

> I started mine about a year ago using HCl and H2O2 (hydrochloric acid -
> branded Muratic acid - 32% strength, and 3% medical grade hydrogen
> peroxide) Both are available locally, HCl about $4 US per gallon and H2O2
> less than $1 per quart. I used two parts H2O2 and one part HCl and got a
> fairly aggressive etchant (about 4 minutes) and yes, it produced nasty
> Chlorine fumes.

Hardly surprising. That's a "piranha mix". I'd be VERY surprised if you
managed to make CuCl etchant out of it - it degrades pretty quickly.
How did you convert it into CuCl? Just dump a load of copper into it to get
rid of the free chlorine?

> There are a few other ways of starting a batch too, though I haven't tried
> them myself. Apparently CuCl powder is available in some areas. IIRC that
> gets added to an acid/water solution.

No easy way to get chemicals in the UK - you need to work for a company that
has a reason (and a damn good one) to require the chemicals, fill out various
forms, etc.
I've heard of people ordering chemicals, then ending up telling the local
police what they wanted them for. From what I've heard they catch a lot of
amateur pyrotechnicians (?) that way...

Later,
--
Phil.                              | Acorn Risc PC600 Mk3, SA202, 64MB, 6GB,
.....philpemKILLspamspam@spam@dsl.pipex.com              | ViewFinder, 10BaseT Ethernet, 2-slice,
http://www.philpem.dsl.pipex.com/  | 48xCD, ARCINv6c IDE, SCSI
... Life. Hate it, or ignore it. You can't like it.
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2004\09\13@122903 by William Chops Westfield

face picon face
>> The only masking system I know of is the resist-ink pen.  Can you
>> provide the low-down on the best way for the hobbyist to mask a board
>> these days?  I already own both inkjet and laser printers...
>>
The BEST way is pretty clearly using pre-coated photosensitive boards,
and photo-exposing them through thin paper or transparency film.

But that's not the easiest or cheapest way.  A lot of people are having
pretty good luck with assorted forms of "toner transfer."  Good data:
http://www.fullnet.com/u/tomg/gooteepc.htm

And it's probably worth pointing out that commercial PCB shops have
come down quite a bit in price, and gotten considerably more convenient
than they used to be.  For about $50, you can get a truly professional
double-sided PCB, complete with soldermask and silkscreens.  For
midsized
boards of moderate complexity, that's a pretty good deal.  If your board
size is small and NOT complex, it can be a poor match...

BillW

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2004\09\13@124446 by William Chops Westfield

face picon face
On Sep 13, 2004, at 8:18 AM, Denny Esterline wrote:

> It's also interesting to note that many board houses do not use this
> etchant. Some processes use tin plating as an etch resist

http://www.thinktink.com/stack/volumes/voliii/consumbl/etchmix.htm

Is a rather similar etchant based on Sulfuric acid and peroxide, but
uses mysterious "organic catalysts" that they want you to purchase.
(thinktink.com has a bunch of interesting info on PCBs...)

It's worthwhile to assume that commercial board houses can be set up
to use etchants that are neither safe or convenient to an amateur.

BillW

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2004\09\13@152630 by Firmware

picon face
> Hardly surprising. That's a "piranha mix". I'd be VERY surprised if you
> managed to make CuCl etchant out of it - it degrades pretty quickly.
> How did you convert it into CuCl? Just dump a load of copper into it to get
> rid of the free chlorine?

Well, yeah- but not so crudely :o) I used it to etch a PCB. And yes it does produce CuCl after adding the copper. Nice emerald green color and everything.

{Quote hidden}

IIRC, it used black copper oxide. Supposedly available in pottery supply stores. Another option used some sort of CuCl2 solid manufactured for cleaning chimney flues (i.e. toss it into the fireplace) - don't ask me how that works :o)

The beauty of HCl and H2O2 is availability. I can't speak for other countries, but here in the USA HCl sold under the common name muratic acid (about 32% strong) is commonly used for adjusting PH in swimming pools and for masonry cleanup. 3% H2O2 (medical grade) is used to wash minor cuts and scrapes. It's available at any pharmacy- even my local grocery store has it for $0.49 a pint.

-Denny


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2004\09\13@184528 by hilip Stortz

picon face
a good idea if you are going to do production and make many, many
boards.  i suspect litho film is pretty tough.  you can also laser print
the layout (on proper transparency stock) and use that as a mask, though
solid dark areas like ground planes can be a problem.  now that you've
mentioned the litho thing, i suppose you could also take a plot and use
it as a mask to make your own litho mask, though from the litho film i'm
vaguely familiar with you may need a lot of uv or time to expose it. mostly the neat thing about using a plotter is you can do it in house
without any delay and solid areas like ground planes come out well. before going the plotter route last time i made boards i tried laser
printing and always had to try to fill in the gray areas that were
supposed to be solid.  it's also fairly cheap, the pens are the main
expense but if you take care of them and don't use the very fine ones
they last a long time.  of course you have to have a plotter or access
to one.

i've also used plotter prints for panel layout and labeling, again
printed backwards so that the ink is towards the box and used super 77
to attach it (though i suspect there are better spray adhesives, i now
know 3m makes some stronger ones).  as i said, this also had the layout
for drilling the panel and worked out very nicely.  the ink is protected
because it's on the inside, and it looks great with the ink on the rough
side of the mylar and the smooth side out.  for this project we just did
it in black and white, but of course you could use color.  i plan to use
the same method on my future projects.  if the panel is already drilled
etc. the holes make a great alignment guide, and the mylar can be cut
easily with an exacto knife where things are to come through it.  it's
also easy to clean the panel which can be a real help.

Falcon Wireless Tech Support - KF4HAZ wrote:
{Quote hidden}

-- Philip Stortz--"In Germany they came first for the Communists, and I
didn't speak up because I wasn't a Communist. Then they came for the Jews, and I didn't speak up because I wasn't a
Jew. Then they came for the trade unionists, and I didn't speak up because I
wasn't a trade unionist. Then they came for the Catholics, and I didn't speak up because I was a
Protestant. Then they came for me, and by that time no one was left to speak up."
-- Martin Niemöller, 1892-1984 (German Lutheran Pastor), on the Nazi
Holocaust, Congressional Record 14th October 1968 p31636.

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2004\09\13@185207 by Philip Pemberton

face picon face
In message <200409131926.i8DJQT3g023006spamKILLspamoutbound3.mail.tds.net>>          <.....firmwareKILLspamspam.....tds.net> wrote:

> > Hardly surprising. That's a "piranha mix". I'd be VERY surprised if you
> > managed to make CuCl etchant out of it - it degrades pretty quickly.
> > How did you convert it into CuCl? Just dump a load of copper into it to get
> > rid of the free chlorine?
>
> Well, yeah- but not so crudely :o) I used it to etch a PCB. And yes it does
> produce CuCl after adding the copper. Nice emerald green color and
> everything.

OK then - what's the mix ratio (Water:H2O2:HCl)?
HCl seems to be available over here, but it's the sort of thing you have to
special-order (or get mail-order). Not sure about peroxide though.

> The beauty of HCl and H2O2 is availability. I can't speak for other
> countries, but here in the USA HCl sold under the common name muratic acid
> (about 32% strong) is commonly used for adjusting PH in swimming pools and
> for masonry cleanup. 3% H2O2 (medical grade) is used to wash minor cuts and
> scrapes. It's available at any pharmacy- even my local grocery store has it
> for $0.49 a pint.

Having just read the MSDSes for H2O2 (3%) and HCl (3% iirc) and some info on
HCl/H2O2 mixes, I don't particularly like the idea of using this stuff... Far
too volatile for my liking... Back to FeCl3 it seems :-/

Later.
--
Phil.                              | Acorn Risc PC600 Mk3, SA202, 64MB, 6GB,
EraseMEphilpemspam_OUTspamTakeThisOuTdsl.pipex.com              | ViewFinder, 10BaseT Ethernet, 2-slice,
http://www.philpem.dsl.pipex.com/  | 48xCD, ARCINv6c IDE, SCSI
... I call my computer Hole in the Desk
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2004\09\13@190425 by hilip Stortz

picon face


Philip Pemberton wrote:
>
> In message <003001c49942$bce48280$0d401545@whythis>
>           "Denny Esterline" <firmwarespamspam_OUTtds.net> wrote:
>
> > I started mine about a year ago using HCl and H2O2 (hydrochloric acid -
> > branded Muratic acid - 32% strength, and 3% medical grade hydrogen
> > peroxide) Both are available locally, HCl about $4 US per gallon and H2O2
> > less than $1 per quart. I used two parts H2O2 and one part HCl and got a
> > fairly aggressive etchant (about 4 minutes) and yes, it produced nasty
> > Chlorine fumes.
>
> Hardly surprising. That's a "piranha mix". I'd be VERY surprised if you
> managed to make CuCl etchant out of it - it degrades pretty quickly.
> How did you convert it into CuCl? Just dump a load of copper into it to get
> rid of the free chlorine?

ok, that makes more sense.  i new there was a process where keeping the
ration of peroxide to hcl was critical and sometimes difficult during
production runs.  and it sounded like there were 2 different but similar
things going on here.
--------
> No easy way to get chemicals in the UK - you need to work for a company that
> has a reason (and a damn good one) to require the chemicals, fill out various
> forms, etc.
> I've heard of people ordering chemicals, then ending up telling the local
> police what they wanted them for. From what I've heard they catch a lot of
> amateur pyrotechnicians (?) that way...
------------

that's terribly unfortunate.  in the u.s. any company can get nearly any
chemical, mind you that they do pay some attention and if you are
obviously ordering things to make drugs or explosives you will have some
explaining to do.  also unfortunate that they go after amateur
pyrotechicians.  that's one of the things that got me and a lot of
people interested in chemistry, and here in the u.s., at least in some
states, it's perfectly legal and i know of a company that specializes in
the necessary supplies and books.  i've seriously considered getting
back into it (i'm in wyoming, plenty of open space and when it's damp
there isn't a fire hazard, though there would be during much of the
year).  this paranoia really doesn't accomplish much in the way of
preventing problems but it does do a lot of harm in not letting people
get interested in this stuff and science in general after a while.  all
the real science geeks i know who know anything about chemistry started
with fireworks, however primitive, and most went on to know far more
than just how fireworks work. but that's just my humble opinion, but
i've seen motivated people get whatever they want, sometimes it
encourages theft which is very unfortunate.  i have the remains of
several chemistry sets in my garage, and the small quantities of
chemicals and chemicals i've purchased, i love chemistry.  for what it's
worth, i'd actually like to see a lot more police than we have here, and
i'd like to see them better trained so they might be friends to more
communities rather than all too often being seen as another problem. i've met some good cops, and some bad ones.

-- Philip Stortz--"In Germany they came first for the Communists, and I
didn't speak up because I wasn't a Communist. Then they came for the Jews, and I didn't speak up because I wasn't a
Jew. Then they came for the trade unionists, and I didn't speak up because I
wasn't a trade unionist. Then they came for the Catholics, and I didn't speak up because I was a
Protestant. Then they came for me, and by that time no one was left to speak up."
-- Martin Niemöller, 1892-1984 (German Lutheran Pastor), on the Nazi
Holocaust, Congressional Record 14th October 1968 p31636.

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2004\09\13@192134 by hilip Stortz

picon face
very true.  people should definitely start with something simple like
FeCl that's easy to handle.  possibly using just etch resist pens at
first and then using some of the simpler photolithography systems.  then
try tin plating and other things like building an etching tank with a
bubler and doing double sided boards.

William Chops Westfield wrote:
-------
>
> It's worthwhile to assume that commercial board houses can be set up
> to use etchants that are neither safe or convenient to an amateur.
---------

i consider myself an amateur only in terms of volume and the probable
lack of need for legend and possibly silk screen (though i'll have to
get into that for surface mount parts).  i know how to handle chemicals
and have had some lab experience and can build complex equipment.  for
me, storage stability and cost will be big issues.  i won't hesitate to
use fairly aggressive and hazardous chemicals if it's not too complex,
short lived, or difficult to properly dispose of or creates particularly
nasty waste.  when i feel good i have plenty of spare time and enjoy
challenging precision work, and i don't have that much money.  there are
a lot of things i'd like to design and build, if i can at all reasonably
figure out through hole plating i won't need a board house for "one off"
things, or small boards.  i've just had a board made in romania, pretty
good quality and 54 of them on a single panel for $45 dollars (they are
10X12 mm, 3 surface mount chips, a connector, 2 caps, and 3 holes for
wires).  now all i have to due is cut them apart with my mill, but i had
them laid out with 1/8" between them so it would be easy.  darn, i can't
remember the name of that company off hand, they do nice work and are
happy to allow multiple parts on a panel if you cut them apart which for
larger boards is easy with a hack saw or band saw.  hell, i just enjoy
developing new skills and doing complex things, and it's great to be
able to do it yourself and know exactly what went on and why there are
or are not defects.  it also lets you use surplus board material which
is often very cheap.

-- Philip Stortz--"In Germany they came first for the Communists, and I
didn't speak up because I wasn't a Communist. Then they came for the Jews, and I didn't speak up because I wasn't a
Jew. Then they came for the trade unionists, and I didn't speak up because I
wasn't a trade unionist. Then they came for the Catholics, and I didn't speak up because I was a
Protestant. Then they came for me, and by that time no one was left to speak up."
-- Martin Niemöller, 1892-1984 (German Lutheran Pastor), on the Nazi
Holocaust, Congressional Record 14th October 1968 p31636.

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2004\09\13@193127 by William Chops Westfield

face picon face
On Sep 13, 2004, at 9:03 AM, Philip Pemberton wrote:

> Hardly surprising. That's a "piranha mix". I'd be VERY surprised if you
> managed to make CuCl etchant out of it - it degrades pretty quickly.
> How did you convert it into CuCl? Just dump a load of copper into it
> to get
> rid of the free chlorine?
>
I think it has a lot less H2O2 than real piranha etchant, and probably
less acid as well.  But yes, you keep adding copper (and air) till you
get a nice deep green solution that starts to precipitate CuClO, and
then add a bit more acid.  At least, that's what I did.  You only need a
little, relatively weak H2O2 to get started.   The easiest copper to add
is scrap stranded copper wire, but copper tubing and such will
eventually
dissolve as well.

BillW


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2004\09\13@205216 by William Chops Westfield

face picon face

On Sep 13, 2004, at 4:23 PM, Philip Stortz wrote:
>> It's worthwhile to assume that commercial board houses can be set up
>> to use etchants that are neither safe or convenient to an amateur.

> i consider myself an amateur only in terms of volume and the probable
> lack of need for legend and possibly silk screen (though i'll have to
> get into that for surface mount parts).  i know how to handle chemicals
> and have had some lab experience and can build complex equipment.  for
> me, storage stability and cost will be big issues.

You have forced air ventilation or a fume hood?  A whole room that can
be made chemical-safe?  Filters on air and drain to make sure that
atomized
spray doesn't leak into the environment?  Lots of money to spend on
specialized etchant-resistant tanks made of exotic alloys or custom
molded polymers, not to mention pumps, spray heads and aereators?

But I was actually thinking along the lines of the "storage stablity"
you specifical mention as being important.  A large PCB factory can
afford to mix of a batch of etchant that will only be good for one day,
if it has other advantages.  An "amateur" (no negative connotations
intended) would find that particularly annoying.

BillW

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2004\09\13@214240 by hilip Stortz

picon face
where are you located out of curiosity?  is it somewhere outside the
u.s. or just a remote area (when i was in socorro new mexico the
hardware store didn't carry plastic tubing, they actually had to order
it for you).  i'm curios about what's available where in general.

Philip Pemberton wrote:
--------
> OK then - what's the mix ratio (Water:H2O2:HCl)?
> HCl seems to be available over here, but it's the sort of thing you have to
> special-order (or get mail-order). Not sure about peroxide though.
-------

-- Philip Stortz--"In Germany they came first for the Communists, and I
didn't speak up because I wasn't a Communist. Then they came for the Jews, and I didn't speak up because I wasn't a
Jew. Then they came for the trade unionists, and I didn't speak up because I
wasn't a trade unionist. Then they came for the Catholics, and I didn't speak up because I was a
Protestant. Then they came for me, and by that time no one was left to speak up."
-- Martin Niemöller, 1892-1984 (German Lutheran Pastor), on the Nazi
Holocaust, Congressional Record 14th October 1968 p31636.

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2004\09\13@230048 by hilip Stortz

picon face
actually, i am planing on eventually having a fume hood (i want to do
chemistry for a research project any way), and it will have filters and
a fire suppression system including the duct work.  i already have 2
blowers (free at the junkyard and out of large furnaces, the bearings
feel great!) and may use one to push fresh air in in case of spill or
fire (more air actually helps control a fire by reducing the
temperature, some fire departments now carry amazing fans for this
purpose, of course it makes it cooler for the fire fighters and easier
to see as well.  i plan to have a separate drain for "clean" water and
handle other liquids separately as warranted.  and as i said, i'm pretty
good at building things, and i'd still be using small tanks that i could
buy and add plumbing to if necessary.  
i will definitely want to try and keep it as simple and "safe" as
possible, but one or two hard to handle chemicals could be dealt with. i also plan to have a DI water system (i can build those as well for a
tiny fraction of the normal cost).  but no, i won't be doing anything
that's too difficult and requires those exotic and expensive metal
alloys and valves etc. of the same.  i also have 2 filtered respirators
(i'd love to get a proper full face air supplied mask) and 2 fire
blankets.  i of course also have several fire extinguishers.  i'd really
like to collect my used solvents and distill them, not that hard with a
hood and fire suppression just in case.

alas, i probably won't have the time to actually set anything that fancy
up, though i'll keep an eye out for good ways to do through hole plating
and might even try to come up with variations.  remember, as a hobby, i
can properly dispose of nearly anything by taking it to the household
hazmat collection point at the dump, as long as i don't go crazy about
it.  and i know they handle it properly.  yeah, my mind has way too much
spare time as compared to my body that is often not very happy.

William Chops Westfield wrote:
{Quote hidden}

-- Philip Stortz--"In Germany they came first for the Communists, and I
didn't speak up because I wasn't a Communist. Then they came for the Jews, and I didn't speak up because I wasn't a
Jew. Then they came for the trade unionists, and I didn't speak up because I
wasn't a trade unionist. Then they came for the Catholics, and I didn't speak up because I was a
Protestant. Then they came for me, and by that time no one was left to speak up."
-- Martin Niemöller, 1892-1984 (German Lutheran Pastor), on the Nazi
Holocaust, Congressional Record 14th October 1968 p31636.

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2004\09\14@075331 by Bob Ammerman

picon face
> The beauty of HCl and H2O2 is availability. I can't speak for other
countries, but here in the USA HCl sold under the common name muratic acid
(about 32% strong) is commonly used for adjusting PH in swimming pools and
for masonry cleanup. 3% H2O2 (medical grade) is used to wash minor cuts and
scrapes. It's available at any pharmacy- even my local grocery store has it
for $0.49 a pint.
>
> -Denny

Higher concentration H202 is available from some swimming pool supply stores
as "BaquaShock". I believe it is 27% or 30%. Costs maybe $20 per gallon. So
you can buy your HCl and H202 with one-stop shopping.

Bob Ammerman
RAm Systems

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2004\09\14@130031 by Byron A Jeff

face picon face
On Mon, Sep 13, 2004 at 04:24:43PM -0700, William Chops Westfield wrote:
> On Sep 13, 2004, at 9:03 AM, Philip Pemberton wrote:
>
> >Hardly surprising. That's a "piranha mix". I'd be VERY surprised if you
> >managed to make CuCl etchant out of it - it degrades pretty quickly.
> >How did you convert it into CuCl? Just dump a load of copper into it
> >to get
> >rid of the free chlorine?
> >
> I think it has a lot less H2O2 than real piranha etchant, and probably
> less acid as well.  But yes, you keep adding copper (and air) till you
> get a nice deep green solution that starts to precipitate CuClO, and
> then add a bit more acid.  At least, that's what I did.  You only need a
> little, relatively weak H2O2 to get started.   The easiest copper to add
> is scrap stranded copper wire, but copper tubing and such will
> eventually
> dissolve as well.

This thread has defintely peaked my interest. First a recap, then questions.

Procedure:

1) Mix 2 parts 3% hydrogen peroxide with 1 part 32% hydrocloric acid, in the
form of muratic acid from the home improvement store.

2) Add stranded copper to dissolve in the solution.

3) Bubble with air to add O2 to the mixture to get stable CuCl etchant.

Questions:

1) Is the above procedure correct?

2) chem question: does it matter how the HCl and H2O2 are mixed? In some
mixtures one reagent need to be stirred into the other. Is that the case here?

3) Are all plastics etchant safe? So bubbling air in a plastic tube is
sufficient, right?

4) We all know that FeCl must be heated to be effective. Is the same true for
CuCl?

I'm sold on this. It's ultra cheap, can be made with readily available
components and can be reconstituted with the cheapest component of all: air.
It's clear too right?

I'm ready to go and make a batch today. But I'll wait until I get answers
to my questions.

Man, I don't see how I'd function without the PICLIST.

BAJ
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2004\09\14@131802 by Byron A Jeff

face picon face
On Tue, Sep 14, 2004 at 01:00:30PM -0400, Byron A Jeff wrote:

Answering some of my own questions. Found a muratic acid site targeted for
cleaning masonry here:

http://www.naturalhandyman.com/iip/infxtra/infmur.shtm

{Quote hidden}

The answer is yes. From the site above:
-------------

IMPORTANT: Always add acid to water... never add water to acid!!  To quote a
knowledgeable reader, Tommy from Corsicana, Texas:

   "When water is added to muriatic acid, an exothermic (heat is given off)
   reaction occurs.  This is often accompanied by a violent "belch" which
   propels the acid mixture out of the container and onto the person making
   the dilution!  This occurs because the heat generated by the reaction is
   under the cooler water and causing it to expand rapidly.  When the acid
   is poured slowly into the water, the cooler water layer is on bottom, so
   the heat generated is dissipated upwards at a slow speed."
--------------

Note that the H2O2 we're using is only at 3% dilution with the rest as
purified water. So I figure it's best to substitute H2O2 for water above to
get

IMPORTANT: Always add acid to H2O2... never add H2O2 to acid!!

The site also follows up with the fact that pouring the acid first can cause
it to splash. So it should be H2O2 first, then acid.

>
> 3) Are all plastics etchant safe? So bubbling air in a plastic tube is
> sufficient, right?

Again from the site:

---
Do not mix in a paper, ceramic or metal bucket... use a plastic bucket.
Glass containers are also acceptable for measuring and mixing.
---

Still looking for my other answers.

Thanks,

BAJ
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2004\09\14@145527 by Byron A Jeff

face picon face
On Mon, Sep 13, 2004 at 05:23:32PM -0600, Philip Stortz wrote:
> very true.

Not so sure.

>  people should definitely start with something simple like
> FeCl that's easy to handle.

Easy to handle one way, but not in others. It isn't clear so you have a
hard time watching the etching process. It stains everything it touches,
it has to be disposed of (and you'd better not pour it down the drain,
and it doesn't function properly unless it's heated unlike CuCl which
will still etch in 15 to 20 minutes at room temp.

>  possibly using just etch resist pens at  first and then using some of
>the simpler photolithography systems.

Even as a rank novice who has never etched a board before I don't think
that's the right approach. With software such as Eagle and gEDA/PCB available
for free for schematic capture,o board layout, and autorouting I think
it's especially important for the novice to start out using the available
tools. With the given technology, the photographic method gives clean,
consistent, repeatable results. While the precoated board do cost more
it's a small price to pay to get boards that actually work. Finally CuCl
gives so many advantages in terms of cost, effectiveness, and
maintainability that there's no good reason to continue using FeCl.

>  then
> try tin plating and other things like building an etching tank with a
> bubler and doing double sided boards.

I think the days of the resist pen on bare copper dipped in FeCl are
over. Nothing about an etching tank is too terribly difficult or
expensive.

BTW another dumb question: Can etchant be heated in a microwave?
I mean it does contain metal right?

BAJ
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2004\09\14@151139 by Firmware

picon face


> This thread has defintely peaked my interest. First a recap, then questions.
>
> Procedure:
>
> 1) Mix 2 parts 3% hydrogen peroxide with 1 part 32% hydrocloric acid, in the
> form of muratic acid from the home improvement store.
>
> 2) Add stranded copper to dissolve in the solution.
>
> 3) Bubble with air to add O2 to the mixture to get stable CuCl etchant.
>
> Questions:
>
> 1) Is the above procedure correct?

Close enough. I didn't add scrap copper wire to mature the batch sooner. I just started etching boards - but I did put up with nasty fumes until the copper content got high enough.

>
> 2) chem question: does it matter how the HCl and H2O2 are mixed? In some
> mixtures one reagent need to be stirred into the other. Is that the case here?
>
You seem to have answered that one :o)

> 3) Are all plastics etchant safe? So bubbling air in a plastic tube is
> sufficient, right?
I can't say 'all', I haven't tested them all. I use a rubbermaid cerial container (about $4 -walmart) and it shows no problems after a year. I used silicone tubing for my bubbler and a regular plastic aqurium difuser- works fine so far but I don't leave it in all the time.

Original I zip tied the difuser to a plastic stick and clamped it to the side of the tank - the ziptie disolved (twice). Now I use a piece of heatshrink and it seems ok. I don't know what kind of plastic the ziptie was. (yes most are nylon, but these were realy cheap and in colors - yellow)

> 4) We all know that FeCl must be heated to be effective. Is the same true for
> CuCl?

Most any chemistry is more reactive when heated, including CuCl. I use it at room temps and have etching times of 8-10 minutes for 1 oz DS material with agitation.

> I'm sold on this. It's ultra cheap, can be made with readily available
> components and can be reconstituted with the cheapest component of all: air.
> It's clear too right?

When mature it's a deep emerald green color. You can see the board ok through a couple inches of it. When it is depleted and ready to be recharged it becomes darker and brown. But etch times are excessivly long before it gets to that point (hours). With a little experiance you can just look at the color and tell when it need recharged.

>
> I'm ready to go and make a batch today. But I'll wait until I get answers
> to my questions.

I'd reccomend reading some of the links on the yahoo group I mentioned a couple days ago (start of this thread) Really, lots of good info about it.

> Man, I don't see how I'd function without the PICLIST.
>
> BAJ

Me niether :o)

-Denny


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2004\09\14@153732 by Support - KF4HAZ

flavicon
face
For Developing, Rinse, and Etch tanks I found a company that sold food
service trays.
They are plastic, have held up well, and will handle 12"x18" boards with a
little room to spare.
Takes a quart or more to process, but then again a smaller quantity would
likely become exhausted before completion.

KF4HAZ - Lonnie

----- From: <firmware@
>
> > This thread has defintely peaked my interest. First a recap, then
questions.
> >
> > Procedure:
> >
> > 1) Mix 2 parts 3% hydrogen peroxide with 1 part 32% hydrocloric acid, in
the
{Quote hidden}

just started etching boards - but I did put up with nasty fumes until the
copper content got high enough.
>
> >
> > 2) chem question: does it matter how the HCl and H2O2 are mixed? In some
> > mixtures one reagent need to be stirred into the other. Is that the case
here?
> >
> You seem to have answered that one :o)
>
> > 3) Are all plastics etchant safe? So bubbling air in a plastic tube is
> > sufficient, right?
> I can't say 'all', I haven't tested them all. I use a rubbermaid cerial
container (about $4 -walmart) and it shows no problems after a year. I used
silicone tubing for my bubbler and a regular plastic aqurium difuser- works
fine so far but I don't leave it in all the time.
>
> Original I zip tied the difuser to a plastic stick and clamped it to the
side of the tank - the ziptie disolved (twice). Now I use a piece of
heatshrink and it seems ok. I don't know what kind of plastic the ziptie
was. (yes most are nylon, but these were realy cheap and in colors - yellow)
>
> > 4) We all know that FeCl must be heated to be effective. Is the same
true for
> > CuCl?
>
> Most any chemistry is more reactive when heated, including CuCl. I use it
at room temps and have etching times of 8-10 minutes for 1 oz DS material
with agitation.
>
> > I'm sold on this. It's ultra cheap, can be made with readily available
> > components and can be reconstituted with the cheapest component of all:
air.
> > It's clear too right?
>
> When mature it's a deep emerald green color. You can see the board ok
through a couple inches of it. When it is depleted and ready to be recharged
it becomes darker and brown. But etch times are excessivly long before it
gets to that point (hours). With a little experiance you can just look at
the color and tell when it need recharged.
>
> >
> > I'm ready to go and make a batch today. But I'll wait until I get
answers
> > to my questions.
>
> I'd reccomend reading some of the links on the yahoo group I mentioned a
couple days ago (start of this thread) Really, lots of good info about it.
>
> > Man, I don't see how I'd function without the PICLIST.
> >
> > BAJ
>
> Me niether :o)
>
> -Denny

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2004\09\14@193436 by William Chops Westfield
face picon face
On Sep 14, 2004, at 10:00 AM, Byron A Jeff wrote:

>
> 2) Add stranded copper to dissolve in the solution.
>
> 3) Bubble with air to add O2 to the mixture to get stable CuCl etchant.
>
> Questions:
>
> 1) Is the above procedure correct?
>
Looks about right.  You don't wait for the copper to dissolve before
starting your bubbling...

> 2) chem question: does it matter how the HCl and H2O2 are mixed? In
> some
> mixtures one reagent need to be stirred into the other.

The general rule is to add acid slowly to water, to prevent heating
from causing splattering.  I suspect that this isn't much of an issue
with HCl (which isn't very strong in the first place), but it's a fine
rule anyway...

> 3) Are all plastics etchant safe? So bubbling air in a plastic tube is
> sufficient, right?
>

Yeah.  Finer bubbles are better.  I used one of the fritted glass
aquarium
aereators (don't put it back in with your fish!)

> 4) We all know that FeCl must be heated to be effective.
> Is the same true for CuCl?

It's about the same as FeCl.  Works OK at room temp, somewhat better
if warm.  If there's free HCl in your etchant, heating will tend to
push it out of solution (nasty fumes.  They'll eat the inside of your
microwave if you let them!)

> It's clear too right?

Not as clear as persulfate; a deep green or blue-green;  Much clearer
than FeCl, though.


users.rcn.com/rexa/Projects/CuCl_ech.html
http://www.pacificsun.ca/~robert/pcb/cucl.htm

BillW

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2004\09\14@231544 by Denny Esterline

picon face
> BTW another dumb question: Can etchant be heated in a microwave?
> I mean it does contain metal right?
>
> BAJ

Metal in a microwave, ha- try smelting in a microwave:
http://home.c2i.net/metaphor/mvpage.html

Metal casting using a common microwave.

-Denny


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2004\09\15@004059 by Russell McMahon

face
flavicon
face
> BTW another dumb question: Can etchant be heated in a microwave?
> I mean it does contain metal right?

I'd be reasonably confident (3 standard deviations) that you'd have no
problems.

Metal per se is NOT a good microwave absorber. Metal smelting actually
requires special absorbers which then transfer the thermal energy to the
metal. Problems with metal in microwave ovens usually arises from closed
conductive loops which couple RF energy. You can (and I have) use flattish
metal pie plates in microwaves with no problems. YMMV / Don't try this at
home if you don't know what you are doing / standard caveats apply  ... :-)


       RM

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2004\09\15@100538 by Support - KF4HAZ

flavicon
face
Flat metal plates do in fact conduct RF in a microwave.
<disclaimer> I take no responsibility if you do try this.
I have microwaved AOL CD's for 2 to 3 seconds, interesting, but could damage
the oven.
I do not know about ionic metal in a microwave but have heated (fresh
unused) Persulfate etchant this way.
The other concern would be chlorine fumes corroding things in the microwave.

KF4HAZ - Lonnie

----- From: "Russell McMahon" <apptech@
{Quote hidden}

:-)
>
>
>         RM
>
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2004\09\24@023555 by hilip Stortz

picon face
i would strongly recommend adding the H2O2 to the water, and then the
HCl so that everything is happening in a larger volume and more diluted.
the more dilute the slower a chemical reaction, the less it heats
(which also speeds up nearly all reactions).  also, doing it more slowly
less Cl gas should be evolved.  you can probably add the copper first or
last, since it will wind up on the bottom it won't react efficiently in
any case and will take some time.  alternatively, i'd add the copper to
the water, and then the HCl, wait the copper to all or mostly dissolve
(which it should, ideally you probably want to add copper until there is
a little left that doesn't dissolve so that you aren't wasting HCl and
releasing extra Cl gas).  and then add the peroxide and let it react. definitely an outside/good ventilation project, if the acid fumes get
strong at all you should leave the area until it clears through the open
window.  note that HCl and many other chemicals will anestize/damage the
nose so that they are harder to smell after a short contact, meaning
that if you start to smell cl, you won't be able to smell it as well
later in the day so it may appear to be diluting out faster than it is,
hence you should leave and come back.  ideally i'd put a good fan in the
window and have my work surface immediately in front of the window and
open another window to let fresh air in.

in any case, i'd definitely do all the chemistry with the water diluting
it for safety.  once a reaction starts to self heat and run away it can
be very hard to slow back down.  definately add a little acid at a time
and wait a few seconds if you haven't done it before.  with experience
you'll have some idea how quickly you can add your chemicals without
things over heating.

the only reason i suggested starting with FeCl is that it avoids having
to make the etchant so you don't have to learn as many things at the
same time, particularly if someone hasn't done any experiments in a chem
lab before or isn't particularly good at it.

i suggested starting with etch resist for the same reason, i.e. having
to learn less at first and preferably making one or two very simple
boards to start.

the whole process from end to end has many steps and is fairly involved.
some people can learn all of it at once, others do much better if they
take it slow.  with any new skill it's often wise to start slow and easy
before trying the more advanced projects.

also, when you are using solvents to strip the etch resist, whether it's
ink or photosensitive types, use plenty of ventilation.  solvents are
very hard on the body with repeated exposure, again livers and kidneys
are expensive, and other organs can be damaged as well.

Byron A Jeff wrote:
-------
>
> Note that the H2O2 we're using is only at 3% dilution with the rest as
> purified water. So I figure it's best to substitute H2O2 for water above to
> get
>
> IMPORTANT: Always add acid to H2O2... never add H2O2 to acid!!
>
> The site also follows up with the fact that pouring the acid first can cause
> it to splash. So it should be H2O2 first, then acid.
--------

-- Philip Stortz--"In Germany they came first for the Communists, and I
didn't speak up because I wasn't a Communist. Then they came for the Jews, and I didn't speak up because I wasn't a
Jew. Then they came for the trade unionists, and I didn't speak up because I
wasn't a trade unionist. Then they came for the Catholics, and I didn't speak up because I was a
Protestant. Then they came for me, and by that time no one was left to speak up."
-- Martin Niemöller, 1892-1984 (German Lutheran Pastor), on the Nazi
Holocaust, Congressional Record 14th October 1968 p31636.



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2004\09\24@023601 by hilip Stortz

picon face


Byron A Jeff wrote:
-----------
>
> >  possibly using just etch resist pens at  first and then using some of
> >the simpler photolithography systems.
>
> Even as a rank novice who has never etched a board before I don't think
> that's the right approach. With software such as Eagle and gEDA/PCB available
--------
as i said, possibly.  learning a lot of things at the same time is
difficult for some people and makes it much harder for them to get it
right, they sometimes even get frustrated and give up.  every pcb board
program i've seen has a significant learning curve, as do schematic
entry programs.  you have to define your parts (or use the libraries if
you like them), make sure you handle power and ground connections
correctly (which is very easy to mess up on most cad programs,
particularly if you use more than one parts library and or your own
parts).  with the board layout you also sometimes have to define new lan
patterns etc., so there can be a lot to do long before breaking out the
copper panels and chemicals.

{Quote hidden}

the dissolved metal, will be metal ions, which is very, very different
than solid metal.  they will tend to make the solution absorb microwaves
faster and heat faster most likely (as they are polarized and hence
react to electric fields).  the problem is you'll be producing etchant
fumes in your' microwave, which won't do anything good for the
microwave.  you'd also want to watch it very closely, if you walked away
and it started boiling a huge volume of fumes would be released, very
bad for the microwave (which you might not be able to get to) the house
and you.  microwaves are used in some chem labs to heat things quickly,
but generally only in closed containers designed to handle the pressure
or those with a vent line that's run out of the microwave through a
suitable hole with some shielding, i.e. it has to go around some plates
that make "shadows" in the microwave field so the microwaves don't leak
too much.

best not to use a microwave for these things unless you are very careful
and don't mind wrecking the microwave.  normally, the best way to heat
etchant is to use a fish tank heater in the tank, they have a glass
sleeve so are compatible with nearly anything (other than solvents
because of the switch contacts and the risk of fire/explosion).  these
are cheap and have a thermostat, it's not calibrated so you definitely
want a glass thermometer or suitable thermocouple probe to set
initially, but once you know what setting is the right temperature you
can mark that on the thermostat.  much better than using a very high
wattage, very quick heating microwave that cost money and has to be
watched like a hawk watching a mouse.

given your' apparent lack of chemical knowledge (and i'm trying to be
helpful, not rude, everyone is ignorant of many things) if you are still
in school i'd strongly suggest taking some chemistry.  it's very useful
in other technical fields and teaches you the basics and the basics of
good lab practice which is important with hazardous chemicals to avoid
injury and property lose.  if not, some self study with a chemistry text
and a chemistry kit are a good idea (though the chemistry kits i've seen
are very weak on theory, it might be better to get a lab manual for an
introductory chem class that goes with the book and try some of the
experiments).  of course if you are going to do chemistry, you should
get a decent balance or scale, ebay is a good place to look for basic
lab ware are some surplus companies.  even just reading through
instructions and expected results for chemical experiments can be
educational and you may have trouble getting some of the chemicals
unfortunately (though the companies that sell chemistry sets cary many
of them in small quantity, i don't know if gilbert has a web site or
not).  in any case, even an expert needs to take care when handling
strong oxidizers, acids, and solvents, particularly in the largish
quantities needed to make a pcb board (there are few if any chem lab
courses that use quarts of reagent at a time!  it's usually a lot less
than an once and only a few grams at a time, just in case, and the
reagents are also usually diluted for safety as well).  any thing you
learn about chemistry will likely be of some use to you in your life.

many chemical supply companies have charts of chemical compatibility,
it's good to check them out.  cole-parmer.com has a good one that you
should be able to download.  sometimes it's surprising what a given
material can or can't handle without problem.


-- Philip Stortz--"In Germany they came first for the Communists, and I
didn't speak up because I wasn't a Communist. Then they came for the Jews, and I didn't speak up because I wasn't a
Jew. Then they came for the trade unionists, and I didn't speak up because I
wasn't a trade unionist. Then they came for the Catholics, and I didn't speak up because I was a
Protestant. Then they came for me, and by that time no one was left to speak up."
-- Martin Niemöller, 1892-1984 (German Lutheran Pastor), on the Nazi
Holocaust, Congressional Record 14th October 1968 p31636.



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2004\09\24@023605 by hilip Stortz

picon face
in some cases, when i was in high school the college across the street
(where we often ate lunch) had an early heavy duty microwave for the
frozen vending foods.  if you put a pop can etc. in it after a while it
would arc to the inside of the oven!  i never did it but i have seen it.
i don't know if the microwaves were rectified at a seem or dissimilar
(different alloy at least) junction and built up a charge or if there
was just an impedance mismatch and it acted like a transformer or if it
acted like a resonant cavity with energy feeding in through the hole at
the top and accumulating until there was enough stored to produce a high
field strength.  it was interesting and mildly amusing.  i've never been
certain what actually caused it though.  
i do know one problem with solid metal in a microwave is that it
reflects microwaves, some of them back into the oscillator making it
dissipate more heat and run at a higher field strength.  of course if
there is some food etc. in there as well, particularly if it's on top of
the metal that will likely absorb enough of the energy to be ok.  it's
also hard on microwaves to run them empty or with very little in them,
particularly on the higher power settings for the same reason, i.e. the
microwaves are not being absorbed so the field strength increases and
more is reflected back to the oscillator and dissipated as heat there,
where you don't want it hot.  if i have very little in the microwave i
always run it on low, that way the average power dissipation stays
reasonable.  
food wrapped on all sides with metal will of course keep the food from
warming and be hard on the microwave.  i have also seen the problem with
metal rings, on older plates that had a metallic paint in a circle
around the outer edge, it burns and discolors the metal and makes the
plate somewhat ugly, and of course you've probably also added some odd
metal vapor to your food along with whatever else was in the paint and
decomposed when it got hot.

Russell McMahon wrote:
{Quote hidden}

-------

-- Philip Stortz--"In Germany they came first for the Communists, and I
didn't speak up because I wasn't a Communist. Then they came for the Jews, and I didn't speak up because I wasn't a
Jew. Then they came for the trade unionists, and I didn't speak up because I
wasn't a trade unionist. Then they came for the Catholics, and I didn't speak up because I was a
Protestant. Then they came for me, and by that time no one was left to speak up."
-- Martin Niemöller, 1892-1984 (German Lutheran Pastor), on the Nazi
Holocaust, Congressional Record 14th October 1968 p31636.



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2004\09\24@080322 by Byron A Jeff

face picon face
On Wed, Sep 15, 2004 at 02:47:51PM -0600, Philip Stortz wrote:
> i would strongly recommend adding the H2O2 to the water,

No need. The H2O2 medical concentration is 3%. It's already diluted in 97%
H2O as I pointed out below. Now if it were the HazMat 30% concentration,
then that's another story.

> and then the
> HCl so that everything is happening in a larger volume and more diluted.

That's what I finally figured out.

>  the more dilute the slower a chemical reaction, the less it heats
> (which also speeds up nearly all reactions).  also, doing it more slowly
> less Cl gas should be evolved.

And I'll probably mix the batch outside for this reason.

>  you can probably add the copper first or
> last, since it will wind up on the bottom it won't react efficiently in
> any case and will take some time.

I plan on shredding it as the more surface area that's available, the faster
it'll dissove. Also the whole batch needs to be bubbled with air to add
additional O2 to the mix.


>  alternatively, i'd add the copper to
> the water, and then the HCl, wait the copper to all or mostly dissolve
> (which it should, ideally you probably want to add copper until there is
> a little left that doesn't dissolve so that you aren't wasting HCl and
> releasing extra Cl gas).  and then add the peroxide and let it react.

No can do because of the concentration of the H2O2 (3%) would overdilute the
HCl (which has a concentration of 31.25% standard in muratic acid).

Denny's whole point was to use cheap, easily accessible items to create
the mix: muratic acid (available at pool supply stores), ordinary medical
peroxide from any grocery shelf, air, and if you like scrap copper. But
the H2O2 and HCl have 97% and 66% H2O diluted already. If you add any more
water, the HCl will be too weak to rtch properly.

For the purposes of this mix, you have to treat the peroxide as if it were
water. So the 2 to 1 peroxide/muratic mix gets the HCl down to its final
15-20% concentration while the weak H2O2 gets enough O2 into the mix to get
the reaction started. Bubbling air adds the rest. The scrap copper stabilizes
the mix into CuCl before you etch the first board, though you can start etching
boards without the copper. Just watch it because it's fast to start off and
will fume Cl. That's why I plan to prep the mix with the scrap copper.

> definitely an outside/good ventilation project, if the acid fumes get
> strong at all you should leave the area until it clears through the open
> window.  note that HCl and many other chemicals will anestize/damage the
> nose so that they are harder to smell after a short contact, meaning
> that if you start to smell cl, you won't be able to smell it as well
> later in the day so it may appear to be diluting out faster than it is,
> hence you should leave and come back.  ideally i'd put a good fan in the
> window and have my work surface immediately in front of the window and
> open another window to let fresh air in.

I plan on working outside until the copper dissolves and the mix turns its
characteristic color. Then the only time you really need to regen outside
is when you add more HCl to the mix.

>
> in any case, i'd definitely do all the chemistry with the water diluting
> it for safety.

Prediluted. That's the difference between using 3% medical peroxide from the
store and the 30% industrial grade H2O2. In fact Denny even points out that
you can't regen spent mix with the 3% stuff because it contains too much water.
That's why you simply bubble the mix to add the additional O2 to the reaction
after you etch. Air gives you O2 with minimal H2O.

>  once a reaction starts to self heat and run away it can
> be very hard to slow back down.  definately add a little acid at a time
> and wait a few seconds if you haven't done it before.  with experience
> you'll have some idea how quickly you can add your chemicals without
> things over heating.

Thanks for that. The link I had posted in my previous post explains how
adding the water to the acid doesn't give the reaction anywhere to expel
the heat, so that it "burps" the mix from the bottom of the mix chamber.

>
> the only reason i suggested starting with FeCl is that it avoids having
> to make the etchant so you don't have to learn as many things at the
> same time, particularly if someone hasn't done any experiments in a chem
> lab before or isn't particularly good at it.

Understood. In fact I have FeCl in the photoetch kit that I bought. But
the negatives far far outweigh the positives in terms of staining, disposal,
cost, and the like.

>
> i suggested starting with etch resist for the same reason, i.e. having
> to learn less at first and preferably making one or two very simple
> boards to start.

The problem I find us that you then you have to relearn several processes
because the simple process will quickly become insufficient for the tasks
that you really want to do. So personally I'd rather spend the time required
to learn how to do the final process I plan to use from the very beginning.

Of course the big dose of "lazy guy" in me finds that optimizing, because
most of the time the final process, while involoved, was originally picked
precisely because in the end it takes less overall work to accomplish.

For example my intended toolchain is the following:

1) gEDA including gschem, gschem2pcb, and PCB. Not as much documentation as
Eagle, but works in my Linux environment, has no board size restrictions, and
of course is free software.

2) Transparancies, positive photoresist PCBs with developer. Got this in a kit
(along with the FeCl above). Generates fast, repeatable results. Though the
boards cost a bit more than bare copper and has a step or two you have to
be time/process sensitive to (darkroom, developer time), everything I have
seen indicates it produces the best, most consistent results.

3) CuCl etching. I had a tough time finding any positive reviews of FeCl. Then
Denny pointed out that a batch of CuCl can be had both easily, cheap, and
without the bother of disposal, and that's all I needed.

I'm still working up to the EZ-Bake SMT toaster oven. But not having to
drill and hand solder is looking real attractive. Plus with SMT you get both
smaller boards and can use a lot of the latest chips that only comes in that
packaging (think 10F parts for example). An alternative I've been researching
for through hole is a CMC drill press coupled with a solder pot that you can
dip the board into.

Each is a step up in complexity from the hand drawn, resist pen, FeCl etching,
hand drill and solder. However in terms of application of process over the
number of boards that will be made, teach step represents a significant
savings in either/all of time, money, complexity, or unreliability.

>
> the whole process from end to end has many steps and is fairly involved.

As outlined above.

>  some people can learn all of it at once, others do much better if they
> take it slow.  with any new skill it's often wise to start slow and easy
> before trying the more advanced projects.

I agree to a point. My break point is having to change processes. I'll do a
small board first. But I still plan to use gschem instead of drawing by hand
for example. I'm certainly not going to layout a multichip Eurocard sized
double sided board with vias the first time out. But when the point is to
learn the process, and by this I mean the final process that you plan to use,
then go ahead and tackle the "Blinky LED" type board with the process that you
actually plan to use.

>
> also, when you are using solvents to strip the etch resist, whether it's
> ink or photosensitive types, use plenty of ventilation.  solvents are
> very hard on the body with repeated exposure, again livers and kidneys
> are expensive, and other organs can be damaged as well.

I'll remember that. It's kind of a hidden step in the overall process.

Thanks for taking the time to discuss the subject.

BAJ
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2004\09\24@111317 by Denny Esterline

picon face
> >  the more dilute the slower a chemical reaction, the less it heats
> > (which also speeds up nearly all reactions).  also, doing it more
slowly
> > less Cl gas should be evolved.
>
> And I'll probably mix the batch outside for this reason.

Always a good choice. When I made my batch I used a glass jar to measure my
chems. I added two pints H2O2 then a pint of acid, two more H2O2 one more
acid ect. Till I had as much as I needed. The whole proccess took about 5
minutes. It did get warm, maybe 100F.

> >  you can probably add the copper first or
> > last, since it will wind up on the bottom it won't react efficiently in
> > any case and will take some time.
>
> I plan on shredding it as the more surface area that's available, the
faster
> it'll dissove. Also the whole batch needs to be bubbled with air to add
> additional O2 to the mix.

I did some rough math based on the specific gravity of the acid/peroxide
and the reccomended SG of mature CuCl. Looks like the 2 parts 3%H2O2 and
one part 32%HCl has a SG of 1.07 and CuCl is reccomended at 1.17 So you'll
need to add about 0.1 gram of copper per cc of etchant (about 100
grams/liter or 13 ounces/gallon)



> >
> > also, when you are using solvents to strip the etch resist, whether
it's
> > ink or photosensitive types, use plenty of ventilation.  solvents are
> > very hard on the body with repeated exposure, again livers and kidneys
> > are expensive, and other organs can be damaged as well.
>
> I'll remember that. It's kind of a hidden step in the overall process.

Definity a good point. I'm using toner transfer and romoving the toner
requires a solvent. Most people seem to be using laquer thinner or acetone,
neither of which would I consider 'healthy'. I've found some medical
adhesive remover wipes to be pleanty effective and no where near as nasty,
but I don't know if they would work for other resist types.

> Thanks for taking the time to discuss the subject.
>
> BAJ
>

No problem, it's been an interesting discussion.

-Denny


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2004\09\24@161831 by Philip Pemberton

face picon face
In message <@spam@AF211AF8-06A6-11D9-AADA-000A95E5DF26KILLspamspammac.com>>          William "Chops" Westfield <KILLspamwestfwKILLspamspammac.com> wrote:

> > 3) Are all plastics etchant safe? So bubbling air in a plastic tube is
> > sufficient, right?
> >
>
> Yeah.  Finer bubbles are better.  I used one of the fritted glass
> aquarium
> aereators (don't put it back in with your fish!)

I've got a similar setup:
 Air pump: Airtech AT2 from a Penn-Plax Smallworld kit (£10.99 from the
   local "Pets at Home" store).
 Aerator: Green Airflex 8-inch (foam?) aerator. £3.49 from the same place as
   the pump. I *think* it's an Airflex, though I'm not 100% about that.
 Container: 2-litre plastic (polypropylene) cereal storage container.
 Warranties: Well and truly voided :)

> It's about the same as FeCl.  Works OK at room temp, somewhat better
> if warm.  If there's free HCl in your etchant, heating will tend to
> push it out of solution (nasty fumes.  They'll eat the inside of your
> microwave if you let them!)

I've got a 5-litre bottle of "Superactivated" ferric chloride concentrate.
0.1% HCl, 40-odd percent FeCl3. It says that the FeCl3 needs diluting if it's
going to be used to etch copper - 70% etchant to 30% water (7:3 ratio). By my
(rough) calculations, that means my 5-litre bottle of concentrate should
produce 7.2 litres of usable solution. The price was right too - about £15
from Farnell Electronics. Considering the stuff Maplin sell is £7.99 for
250ml and is pre-diluted (and doesn't contain any HCl, so it produces loads
of sludge), I think £15 for 5 litres is a pretty good deal. Umn.. Anyone
wanna buy some ferric chloride? :P

> users.rcn.com/rexa/Projects/CuCl_ech.html
> http://www.pacificsun.ca/~robert/pcb/cucl.htm

Or there's always the book "Electronic Prototype Construction" by Stephen
Kasten - ISBN 0-672-21895-X, published by Sams. It's out of print; I got my
copy from a company called Alibris who had it listed for sale on
Amazon.co.uk. If you can get a copy, it's well worth having, if only for the
sections that cover prototype PCB manufacture. ISTR it also covers wire-wrap
and a few other construction methods.

Later.
-- Phil.                              | Acorn Risc PC600 Mk3, SA202, 64MB, 6GB,
RemoveMEphilpemTakeThisOuTspamphilpem.me.uk              | ViewFinder, 10BaseT Ethernet, 2-slice,
http://www.philpem.me.uk/          | 48xCD, ARCINv6c IDE, SCSI
... A wise man once said.... I don't know...
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2004\09\24@164236 by Peter L. Peres

picon face

On Fri, 24 Sep 2004, Denny Esterline wrote:

> I did some rough math based on the specific gravity of the acid/peroxide
> and the reccomended SG of mature CuCl. Looks like the 2 parts 3%H2O2 and
> one part 32%HCl has a SG of 1.07 and CuCl is reccomended at 1.17 So you'll
> need to add about 0.1 gram of copper per cc of etchant (about 100
> grams/liter or 13 ounces/gallon)

So you could boil some of the water off I think ? Would HCl evaporate
before you lose enough water ?

Peter
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2004\09\24@213306 by Denny Esterline

picon face

>
> On Fri, 24 Sep 2004, Denny Esterline wrote:
>
> > I did some rough math based on the specific gravity of the
acid/peroxide
> > and the reccomended SG of mature CuCl. Looks like the 2 parts 3%H2O2
and
> > one part 32%HCl has a SG of 1.07 and CuCl is reccomended at 1.17 So
you'll
> > need to add about 0.1 gram of copper per cc of etchant (about 100
> > grams/liter or 13 ounces/gallon)
>
> So you could boil some of the water off I think ? Would HCl evaporate
> before you lose enough water ?
>
> Peter

I guess my brain was faster than my fingers. I meant to point out that mine
has less than half that much copper in it and it seems to work fine.

I don't think I'd consider trying to boil off the water to raise the sg.
First, it'll produce nasty fumes, then you can't be certain what ratios you
have left (at least not without proper lab facilities for testing)

-Denny


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2004\09\25@025820 by hilip Stortz

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i definitely would not boil it!  at best, you'll get Cl2 fumes, more
likely HCl fumes, which are far worse.  most acids will evaporate/boil
faster than water, acids can be distilled to get stronger, drier acids
so you'd actually be lowering the CuCl concentration.

another question, do you need H2O2 at all or is just bubbling air
through adequate?

also, specific gravity isn't going to tell you much about the chemistry
of your etchant in this case, as the chemistry is too complex.  H2O2
will disassociate and releases O2, HCl will release Cl2 and/or H2, and
there are several other reactions going on as well.  you can't tell if
the specific gravity is high/low because of any specific component of
the mixture because there are several, and they are not in constant
ratio's to each other.  you'd probably need spectroscopy or ion
selective electrodes to really get any idea what exactly was in your
etchant at any given time, or some other selective way to measure the
individual ions etc. in the solution.  i remember this also being a very
large problem with the piranha type etchants which require a high level
of H2O2 but still require balance with the HCl and residual copper
compounds.  for that matter, you do realize that the solution does not
have HCl or CuCl in it, it has H+ ions, Cu+ ions (and possibly in
several different oxidation states) and Cl- ions in a water solution,
which with solutions like this isn't just H2O anyway, but a complex
mixture of several species even when not complicated by other ions?  you
only actually have CuCl if you evaporate off all of the water and HCl.

"Peter L. Peres" wrote:
{Quote hidden}

--------

-- Philip Stortz--"In Germany they came first for the Communists, and I
didn't speak up because I wasn't a Communist. Then they came for the Jews, and I didn't speak up because I wasn't a
Jew. Then they came for the trade unionists, and I didn't speak up because I
wasn't a trade unionist. Then they came for the Catholics, and I didn't speak up because I was a
Protestant. Then they came for me, and by that time no one was left to speak up."
-- Martin Niemöller, 1892-1984 (German Lutheran Pastor), on the Nazi
Holocaust, Congressional Record 14th October 1968 p31636.

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2004\09\25@103012 by Peter L. Peres

picon face

On Sat, 25 Sep 2004, Philip Stortz wrote:

> i definitely would not boil it!  at best, you'll get Cl2 fumes, more
> likely HCl fumes, which are far worse.  most acids will evaporate/boil
> faster than water, acids can be distilled to get stronger, drier acids
> so you'd actually be lowering the CuCl concentration.

I'm pretty sure most acids can be concentrated by boiling, but maybe not
HCl. Also boiling would likely decompose any H2O2 present. So, boiling HCl
to concentrate it is probably a bad idea.

Peter

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2004\09\25@121812 by Daniel Chia

flavicon
face
Not all acids can be boiled to concentrate it mainly due to fume
concerns... HCl releases HCl fumes esp when its concentrated and its
harmful (must be used in fume cupboard). Nitric acid releases NO2 fumes
(nasty stuff, eats almost everything)..

So I think before you heat the acid you better make sure nothing nasty
is gonna come out.

------------------------------------------------------------------------
Daniel Chia

"Genius is one percent inspiration and ninety-nine percent
perspiration."

    - Thomas Edison

E-mail: spamBeGonedanielcjhspamBeGonespamyahoo.com.sg
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> {Original Message removed}

2004\09\25@135634 by William Chops Westfield

face picon face
On Sep 25, 2004, at 12:00 PM, Philip Stortz wrote:

> another question, do you need H2O2 at all or is just bubbling air
> through adequate?

You need the H2O2 to generate CuCl2 etchant from HCl and raw copper.
If you have another way to get CuCl2, you don't need the peroxide.
You can start with actual CuCl2, or CuO, and perhaps CuClO...

>
> also, specific gravity isn't going to tell you much about the chemistry
> of your etchant in this case, as the chemistry is too complex.  H2O2
> will disassociate and releases O2, HCl will release Cl2 and/or H2, and
> there are several other reactions going on as well.

Those are "transient" reactions on your way to a simpler etchant.
H2O2, Cl2, H2 are not involved anymore.  Once you've reached "stable",
you can monitor things with only specific gravity and pH.
See here:
   http://users.rcn.com/rexa/Projects/CuCl_ech.html

Most of the people here who are experimenting with CuCl2 etchant are
using some combination of CuCl2 and H2O2/HCl, but that's not what
you're AIMING for if you're measuring specific gravity...

BillW

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2004\09\25@151732 by Wouter van Ooijen

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> I'm pretty sure most acids can be concentrated by boiling,
> but maybe not HCl.

IIRC from chemistry classes the amount of any gas that can dissolve in
water approaches 0 when the water temperature reaches the boiling point.
HCl is a gas...

Wouter van Ooijen

-- -------------------------------------------
Van Ooijen Technische Informatica: http://www.voti.nl
consultancy, development, PICmicro products
docent Hogeschool van Utrecht: http://www.voti.nl/hvu


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2004\09\25@234409 by Byron A Jeff

face picon face
On Fri, Sep 24, 2004 at 10:09:41PM -0400, Peter L. Peres wrote:
>
> On Fri, 24 Sep 2004, Denny Esterline wrote:
>
> >I did some rough math based on the specific gravity of the acid/peroxide
> >and the reccomended SG of mature CuCl. Looks like the 2 parts 3%H2O2 and
> >one part 32%HCl has a SG of 1.07 and CuCl is reccomended at 1.17 So you'll
> >need to add about 0.1 gram of copper per cc of etchant (about 100
> >grams/liter or 13 ounces/gallon)
>
> So you could boil some of the water off I think ? Would HCl evaporate
> before you lose enough water ?

As others have pointed out it's a bad idea.

BTW I've had some sucess in mixing up my first batch. I started by purchasing
muratic acid from the Home Depot. Got a gallon for $3.44 US. Already had the
medical H2O2 at home (1 quart). It didn't seem to be enough. I'll need to
get another bottle tomorrow. Spent an hour or so shredding an old extension
cord to get stranded copper. Mixed outside in the given ratios. It fizzed
a bit and quickly settled down to a spectacular seafoam green color.

It looks like I need to double or triple the amount I used to get a good batch.
It looks like the gallon of HCl could last quite a while.

BAJ
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2004\09\26@024429 by William Chops Westfield

face picon face
On Sep 25, 2004, at 8:44 PM, Byron A Jeff wrote:

> Already had the medical H2O2 at home (1 quart).
>  It didn't seem to be enough.

Really?  You should only need a bit of H2O2 to get things started.
Once you get 'some' CuCl2, that should act as an etchant as well,
as long as you continue to bubble air through it.  It does take
quite a while; I spent several days tossing in copper and letting
it aereate overnight or until the copper was gone.  Copper wire is
pretty thick by PCB standards.  You can go faster with concentrated
HCl and strong H2O2, but that's not necessarily the point..

(you keep adding copper till the copper doesn't disolve, even with
the aereation.  I got a nice light-bluegreen power precipitating, which
I suspect was copper oxychloride.  The usual "spent etchant" for this
stuff is brown sludge; so if you're not getting brown sludge, you can
keep adding more copper.)

BillW

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2004\09\26@074700 by Howard Winter

face
flavicon
picon face
Bill,

On Sat, 25 Sep 2004 23:44:25 -0700, William "Chops"
Westfield wrote:

> you keep adding copper till the copper doesn't
disolve, even with the aereation

I haven't been paying much attention to this thread so I
may have missed something, but if it doesn't dissolve
copper, how does it act as an etchant?

Cheers,


Howard Winter
St.Albans, England


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2004\09\26@100907 by Byron A Jeff

face picon face
On Sat, Sep 25, 2004 at 11:44:25PM -0700, William Chops Westfield wrote:
> On Sep 25, 2004, at 8:44 PM, Byron A Jeff wrote:
>
> >Already had the medical H2O2 at home (1 quart).
> > It didn't seem to be enough.

The Sterlite plastic container than came with the kit here:

http://www.mgchemicals.com/products/416k.html

seems to be about 5 quarts and I started my batch with less than 1.5 qts
of etchant. So it's a pretty thin layer on the bottom.

>
> Really?  You should only need a bit of H2O2 to get things started.

It worked. Just not enough volume in my estimation.

> Once you get 'some' CuCl2, that should act as an etchant as well,
> as long as you continue to bubble air through it.

I was so pumped about getting the HCl I just wanted to test the reaction.
Today I plan on working on the the bubbler.

>  It does take
> quite a while; I spent several days tossing in copper and letting
> it aereate overnight or until the copper was gone.  Copper wire is
> pretty thick by PCB standards.  You can go faster with concentrated
> HCl and strong H2O2, but that's not necessarily the point..

Exactly. After seeing the smoking from the 31.25% HCl I have no intention
of going any stronger. The whole point of the medical peroxide is that
it's available everywhere for pennies.

But I need a certain amount of peroxide to get the volume of liquid I want.
Denny's formula uses the peroxide as the water component too diluting the
HCl. So he suggests a 2 to 1 mix of H2O2 to the HCl. I have enough muratic
acid, but I ran out of peroxide. I'll run to the corner store and buy another
quart.

Time is on my side. Once I get the bubbler going I can let it go a couple
of weeks just tossing in copper that I'm getting from my ripped up extension
cord.

>
> (you keep adding copper till the copper doesn't disolve, even with
> the aereation.  I got a nice light-bluegreen power precipitating, which
> I suspect was copper oxychloride.  The usual "spent etchant" for this
> stuff is brown sludge; so if you're not getting brown sludge, you can
> keep adding more copper.)

Good to know. I'm thinking to get the volume more contained I may get a
2 qt round pitcher to mix up the etchant. Then the bubbler should be more
effective because there's less surface area to cover.

BAJ
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2004\09\26@101134 by Byron A Jeff

face picon face
On Sun, Sep 26, 2004 at 12:46:54PM +0100, Howard Winter wrote:
> Bill,
>
> On Sat, 25 Sep 2004 23:44:25 -0700, William "Chops"
> Westfield wrote:
>
> > you keep adding copper till the copper doesn't
> disolve, even with the aereation
>
> I haven't been paying much attention to this thread so I
> may have missed something, but if it doesn't dissolve
> copper, how does it act as an etchant?

When it gets to equilibrium you add a spot more HCl which is the only reagent
actually consumed in the whole reaction. Also it's a self regenerating
reaction, where adding O2 regenerates back to CuCl which will accept more
copper.

BAJ
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2004\09\26@170557 by William Chops Westfield

face picon face
On Sep 26, 2004, at 4:46 AM, Howard Winter wrote:

>> you keep adding copper till the copper doesn't
>> disolve, even with the aereation
>
> I haven't been paying much attention to this thread so I
> may have missed something, but if it doesn't dissolve
> copper, how does it act as an etchant?
>
>
That wasn't clear, was it :-)  You're starting with HCl, and the idea
is to get "all" of the HCl converted to CuCl2, so that you're etching
with CuCl2 and not HCl/H2O2.  So when copper stops dissolving, you
have essentially "spent" etchant, which can then be measured and
replenished via the 'standard' instructions WRT specific gravity and
pH.  I suppose you don't have to go quite that far if all you really
want to worry about is etching boards.

BillW

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2004\09\26@175238 by William Chops Westfield

face picon face
On Sep 26, 2004, at 7:09 AM, Byron A Jeff wrote:

> But I need a certain amount of peroxide to get the volume of liquid I
> want.
> Denny's formula uses the peroxide as the water component too diluting
> the
> HCl. So he suggests a 2 to 1 mix of H2O2 to the HCl. I have enough
> muratic
> acid, but I ran out of peroxide.

Oh, I get it...  Yes, that won't hurt anything, as far as I know.
IIRC, I started with 1:1:1 or so HCl, H2O2 (3%), and water.  I
should do a more controlled generation where I pay attention; like
you I got enthusiastic just to see things working :-)

You might want to do your initial CuCl2 generation in a tall bottle
rather than a shallow tray.  I did mine in a 2l soda bottle with the
top cut off (and put back on funnel-style to help contain foaming,
spray, and fumes.)  It's a lot easier to get a wad of copper wire
submerged in a 6 inch deep bottle than in a PCB-etching tray.

BillW

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2004\09\27@152936 by Peter L. Peres

picon face

On Sun, 26 Sep 2004, Howard Winter wrote:

> Bill,
>
> On Sat, 25 Sep 2004 23:44:25 -0700, William "Chops"
> Westfield wrote:
>
>> you keep adding copper till the copper doesn't
> disolve, even with the aereation
>
> I haven't been paying much attention to this thread so I
> may have missed something, but if it doesn't dissolve
> copper, how does it act as an etchant?

As I understand it it's a 2-step process. Adding the copper in the
beginning makes the etchant (which contains copper). It gets better the
more you add. I.e. as you etch boards you produce more etchant... just
getting it started seems hard for some.

Peter
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2004\09\27@181537 by hilip Stortz

picon face
absolutely, and you'd better have the right kind of "still" to collect
the vapors.  i believe that nitric acid can be distilled (evaportated?)
to a higher concentration, though you'll also want to clean your' fume
hood afterwards....  best not to heat or boil a solution without some
idea of what will come out. freezing can also be a problem, particularly
for those acids that release fumes.  in any case, it's better not to
hear most chemical solutions, or heat them only as much as is required.

Daniel Chia wrote:
>
> Not all acids can be boiled to concentrate it mainly due to fume
> concerns... HCl releases HCl fumes esp when its concentrated and its
---------

-- Philip Stortz--"In Germany they came first for the Communists, and I
didn't speak up because I wasn't a Communist. Then they came for the Jews, and I didn't speak up because I wasn't a
Jew. Then they came for the trade unionists, and I didn't speak up because I
wasn't a trade unionist. Then they came for the Catholics, and I didn't speak up because I was a
Protestant. Then they came for me, and by that time no one was left to speak up."
-- Martin Niemöller, 1892-1984 (German Lutheran Pastor), on the Nazi
Holocaust, Congressional Record 14th October 1968 p31636.

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2004\09\27@182147 by hilip Stortz

picon face


William Chops Westfield wrote:
>
> On Sep 25, 2004, at 12:00 PM, Philip Stortz wrote:
>
> > another question, do you need H2O2 at all or is just bubbling air
> > through adequate?
>
> You need the H2O2 to generate CuCl2 etchant from HCl and raw copper.
> If you have another way to get CuCl2, you don't need the peroxide.
> You can start with actual CuCl2, or CuO, and perhaps CuClO...

so does it act as a catalyst or do you actually need to oxidize the
copper first in order to get the chloride?  that seems odd though possible.

{Quote hidden}

oh, if you are also measuring Ph, you can account for considerable
changes in just which species are left in solution.  seems to me that
people also look at the color, which would be 3 measurements which would
definitely account for several variables.  thanks for the link however,
which explains the reaction in more detail, explaining that it's
necessary for changing the oxidation level of the copper which makes
total sense.

---------

-- Philip Stortz--"In Germany they came first for the Communists, and I
didn't speak up because I wasn't a Communist. Then they came for the Jews, and I didn't speak up because I wasn't a
Jew. Then they came for the trade unionists, and I didn't speak up because I
wasn't a trade unionist. Then they came for the Catholics, and I didn't speak up because I was a
Protestant. Then they came for me, and by that time no one was left to speak up."
-- Martin Niemöller, 1892-1984 (German Lutheran Pastor), on the Nazi
Holocaust, Congressional Record 14th October 1968 p31636.

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2004\09\27@190314 by hilip Stortz

picon face
it seems from the earlier link, you can use H2O2 and/or aeration, H2O2
is just faster.  since it's also dirt cheap, i'd use a lot of H2O2 to
get started.

William Chops Westfield wrote:
--------
didn't seem to be enough.
>
> Really?  You should only need a bit of H2O2 to get things started.
> Once you get 'some' CuCl2, that should act as an etchant as well,
> as long as you continue to bubble air through it.  It does take
> quite a while; I spent several days tossing in copper and letting
> it aereate overnight or until the copper was gone.  Copper wire is
> pretty thick by PCB standards.  You can go faster with concentrated
> HCl and strong H2O2, but that's not necessarily the point..
--------

-- Philip Stortz--"In Germany they came first for the Communists, and I
didn't speak up because I wasn't a Communist. Then they came for the Jews, and I didn't speak up because I wasn't a
Jew. Then they came for the trade unionists, and I didn't speak up because I
wasn't a trade unionist. Then they came for the Catholics, and I didn't speak up because I was a
Protestant. Then they came for me, and by that time no one was left to speak up."
-- Martin Niemöller, 1892-1984 (German Lutheran Pastor), on the Nazi
Holocaust, Congressional Record 14th October 1968 p31636.

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2004\09\27@234005 by William Chops Westfield

face picon face
On Sep 28, 2004, at 4:05 AM, Philip Stortz wrote:

> it seems from the earlier link, you can use H2O2 and/or aeration, H2O2
> is just faster.

I found some explanation for the H2O2/acid reaction here:

http://antoine.frostburg.edu/chem/senese/101/redox/faq/h2o2-cu.shtml

Basically, it goes:

   Cu(s) + H2O2(aq) + 2 H+(aq) = Cu2+(aq) + 2 H2O(l)

So in solution starting with HCl, you have both the H+ and the Cl-
participating in etching reactions.

BillW

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