Homebrew PCBs

WOW!

I've been reading all this chaff about what my Mom called "peroxide", 
and how, ever since I can remember, there
was always a bottle of this stuff somewhere in the house. No one ever 
got gassed, burned, blistered, or was
rendered unconscious by the stuff, and she spilled on all three of her 
kids whenever we fell down and scrapped
a knee or cut a finger.  Of course, the stuff we had in the house was 
the "ordinary" stuff she purchased at the
Rexall drug store along with iodine and Band-Aids.

Well, many, many years later, I still have at least a liter of the stuff 
in the house and another out in my
workplace. I use the workplace "stash" for making printed circuit boards.

Living in southern Arizona on the Sonoran Desert, nearly everyone has a 
backyard swimming pool, or at least
there are three or four on every block. That means that most garages or 
backyard sheds have several gallons
of muriatic acid sitting around. You need the stuff to maintain your 
pool. I've never witnessed or even heard
of any catastrophes in having a neighborhood that is loaded down with 
5-gallon jugs of the stuff.
Of course, one must use basic intelligence in using the stuff.

I've lived here for nearly 30 years, and I have never heard of anyone 
getting messed up from  muriatic acid.
OR drug store peroxide. You  "Google" muriatic acid and find out what it is.

When making a PC board, I just mix up the generally recommended compound 
of 75% peroxide, and
25% muriatic acid. The stuff works on 1-oz. copper like a "dose of Epson 
Salts through a widow woman",
as my Grandpa used to exclaim.

The caveats are: Use the rule you learned in high school chemistry class 
about how to mix acids with other
things, including water, and to always work with and use chemicals (of 
any type) in a well-vented area.

No need to get fancy or get exotic. The above compound works well at 
room temp.  I usually do my etching
outdoors because I can take advantage of the usual 100 degree heat that 
we get, free of charge, most of
the year out here in "rattlesnake country".  Chemical reactions are 
speeded up by application of heat.
I learned that in high school chem. class also......as long as you don't 
" overshoot the groove".

Life is really pretty easy...........if you don't fight it.

Roland F. Harriston, P.D.
***************************

On 3/13/2013 11:59 AM, Todd F. Carney / K7TFC wrote:
>
> Charlie,
>
> Well, I may have overstated the nastiness of the fumes. It's really no
> worse in use than, say, photo stop bath or fixer--both of which have a
> fairly-strong acetic-acid (vinegar) smell. There's no evil-scientist smoke
> or anything. For me, it's a kind of DIY thing. I make my own salad
> dressing, too . . . not with the hydrochloric, mind you!
>
> 73,
>
> Todd
> ----------------------------------------------------------
> K7TFC / Medford, Oregon, USA / CN82ni / UTC-8
> ----------------------------------------------------------
> QRP (CW & SSB) / EmComm / SOTA / Homebrew / Design
>
> On Wed, Mar 13, 2013 at 9:09 AM, Missouri Guy <n0tt1@... 
> <mailto:n0tt1%40juno.com>> wrote:
>
> > OK, thanks Todd. Nasty fumes from the stuff!! I think I'll just
> > stick with the Ferric Chloride....seems to be the most "user friendly"
> > for occasional use.
> >
> > Good idea on the vent system you have there!
> >
> > 73,
> > Charlie
> >
> > On Tue, 12 Mar 2013 22:25:31 -0700 "Todd F. Carney / K7TFC"
> > <k7tfc@... <mailto:k7tfc%40arrl.net>> writes:
> >
> > On Tue, Mar 12, 2013 at 6:52 PM, Missouri Guy <n0tt1@... 
> <mailto:n0tt1%40juno.com>> wrote:
> >
> > > **
> > >
> > > . . . Lemme ask this...I'm assuming that the etching should NOT be 
> done
> > in
> > > full sunlight because of the H2O2. Is that correct?
> > > Or does it make any difference because it is mixed with the
> > hydrochloric
> > > acid? . . .
> > >
> >
> > Charlie,
> >
> > I don't know anything about the photoreactivity of the mixture. The high
> > UV
> > from the sun probably does something. The stuff should definitely be 
> used
> > outside as it has very pungent fumes, mostly from the acid I think. Care
> > must be taken in just opening the acid jug, it's that strong. Naturally,
> > proper protection for the eyes and bare skin is in order. I use shop
> > goggles and exam gloves and I wear old cloths. In this winter cold, I
> > used
> > a rigged-up vent booth in my laundry room for both small-object spray
> > painting and etching. A strong fan in the back of a big cardboard box
> > just
> > blows the fumes out the window.
> >
> > Regarding disposal, there has been a thread running lately in this group
> > you should look up. Since I use my 2:1 etchant "one-shot" in 2oz
> > quantities, I once just poured it down the drain afterwards. Deciding
> > that
> > was not responsible, I then began to dump the "shots" into a bucket
> > filled
> > with wood shavings. I assumed the shavings would "sequester" (oh, that
> > word!!) the copper-ladden chemical in a form that, once dry, could just
> > be
> > carefully bagged and sent to the landfill.
> >
> > This morning, though, I read a post from . . . damn!, can't remember his
> > name . . . who observed all I was doing was to create more toxic waste.
> > He
> > suggested the spent etchant be treated with sodium carbonate. This would
> > have two benefits: it would neutralize the acid, and it would 
> precipitate
> > an insoluble copper compound that could then be filtered out and dried
> > before ordinary disposal. He further suggested the precipitate could be
> > made even safer by baking out carbon in the form of CO2, leaving 
> behind .
> > .
> > . damn! I can't remember the compound that would remain . . . but he 
> said
> > it could be very safely disposed of in the landfill. I'm going to pursue
> > this idea. Check out the thread.
> >
> > 73,
> >
> > Todd
> > ----------------------------------------------------------
> > K7TFC / Medford, Oregon, USA / CN82ni / UTC-8
> > ----------------------------------------------------------
> > QRP (CW & SSB) / EmComm / SOTA / Homebrew / Design
> >
> > [Non-text portions of this message have been removed]
> >
> >
> >
> >
> > [Non-text portions of this message have been removed]
> >
> >
> >
> > ------------------------------------
> >
> > Be sure to visit the group home and check for new Links, Files, and 
> Photos:
> > http://groups.yahoo.com/group/Homebrew_PCBsYahoo! Groups Links
> >
> >
> >
> >
>
> [Non-text portions of this message have been removed]
>
> 



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