Homebrew PCBs

I'm working on a low cost Copper Chloride spray system for single and
double sided boards and I wanted to run what I'm doing by you guys and
see if anyone had already worked on this or had any thoughts.   My
plan is to use either 5 or 9 conical spray pattern applicators per
side inside of a small one piece acrylic fishtake with a maximum PCB
size of 8.5" X 11" and a practical working size of about 6" X 9".  
About 1" of the bottom of the tank will serve as the pump reservoir.

I found that I can get a diaphragm pump with Viton fittings and
Santoprene diaphragm for about $45 (both A rated for Copper Chloride). 

I checked on the applicators for aerosol cans and they're made of HDPE
which is rated B for Copper Chloride, so I contacted Seaquist and
asked them to send me 20 samples of their AR-100.   Even though these
have a B rating, I'm not too worried since if they fail they will be
inside of the enclosed etching tank.

If I can keep the temp below 72F I can use any kind of tubing (silicon
 and PVC are A1 rated), but since I don't want to be limited in that
way I plan to use Santoprene because Viton is quite expensive.

For fittings I think I have to stick with Kynar since these will be
outside of the tank.   I'm undecided about using HDPE because, even
though it is B rated, the deluxe etching system by MG Chemical uses it
for their tanks.

I haven't sourced the tubing or fittings yet, so I plan on doing some
calling this week.   Hopefully I can get samples so as to keep costs
down.   I have set a limit of about $100 for this system because it is
still much less than the $170 MG Chemical deluxe system.   More than
that and I don't think it can be considered anywhere near low cost for
a hobbyist.

I'd really appreciate any feedback, especially concerning using HDPE
with Copper Chloride since that could make or break my budget.   Also,
if anyone knows low cost sources for flexible Santoprene tubing (3/8"
ID) and/or Kynar T fittings (3/8" OD) I'd love to hear from them!

Thanks,
Seth

On Tue, 25 Jul 2006 15:56:59 +0200, sethkoster <sethkoster@...>  
wrote:

>
> I'd really appreciate any feedback, especially concerning using HDPE
> with Copper Chloride since that could make or break my budget.   Also,
> if anyone knows low cost sources for flexible Santoprene tubing (3/8"
> ID) and/or Kynar T fittings (3/8" OD) I'd love to hear from them!
> Thanks,
> Seth


I have not tried CuCl in HDPE long term, but i can tell you that  
concentrated HCl will form salts or something on the outside of a HDPE  
chemicals bottle. H2O2 will make the inside of the HDPE bottle brittle.

In finished CuCl the concentrations are much lower, so it may be fine. If  
you keep CuCl in a thick walled PET bottle it will also form salts or  
crystals on the outside.

ST