Homebrew PCBs

On Fri, Jan 14, 2011 at 9:56 PM, Nathan House
<nathanhooyagroups@...> wrote:
>
> So it sounds like building a tank will probably work, but may not be worth
> it. I guess I'll have to think about it some more before deciding whether to
> do it or not. I'd love to hear more input from people who have tried it
> though..
>
> Have you guys had any problem with the fumes from the HCl corroding metal in
> the vicinity? I haven't noticed this, but I recently posted on a chemistry
> forum and they said this would be a severe long-term problem.
>
> I'm also curious how you protect yourselves from the fumes. When I'm etching
> I *try* to do it in a fairly ventilated place, but the fumes still smell
> extremely strong and I can't help wonder if I should be wearing a respirator
> or something..

I use the smallest fish tank (glass, with a glass top that fits into
the grooves on the top --PetsMart) I have been able to find (15 cm x
30cm/6"x12", 9.5 L), and the silicone sealant on it has held up for
many months of holding the solution without any sign of degradation.
I may have been using a weaker solution than most people use since it
does take a while to etch, but I'm not in a hurry and the fumes are
really minimal.  When I am not using it I use a plastic garbage bag
and wrap it securely around the whole tank to prevent any fumes and
have never had a problem since.

I used a partially-covered polypropylene container in a basement for a
while and the solution *was* stronger and it corroded virtually
everything in the basement area, including chrome-plated racks, steel
bar stock, and basically anything that it could attack.  The odor
itself was only really noticeable when bubbling/etching.  I no longer
trust bubblers since they by nature tend to create a fine mist of
etchant that spreads everywhere.  I now use a sacrificial fountain
pump (All of about 5-7$, smallest size) to circulate the etchant which
works very well.  The pumps last a long time as long as you don't
leave them in the etchant permanently and rinse them after etching.  I
highly recommend these type of pumps since they are very well sealed,
there is no moving part besides the magnet and generally the glue
holding the impeller to the magnet breaks down first, which is easily
repaired.  Eventually the magnet itself dissolves but that hasn't been
a problem with temporary use/rinsing.  Also great for electroplating
solutions which use similarly aggressive acids and must have
agitation.

Larry