Homebrew PCBs

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@...> writes:
  
On Tue, Mar 12, 2013 at 6:52 PM, Missouri Guy <n0tt1@...> 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]