Markus Zingg wrote:
> Hi Adam
>
> First off - let me thank you for the critical feedback. I am in fact
> not experineced and therefore thankfull for any information.
I can give tips on the acid copper plating since I have a
bit of experience with this. I have been doing small amounts
of copper plating for about 2 years now. I've been through
about 3 major tanks revisions before I had something working.
> I figure I could change the setup so as all of the anodes would be
> floded. However, I don't understand how I should avoid that copper is
> not covered by the acid on one hand, but not having any other material
> reach the acid on the other hand.
The corrosion is due to a electrochemical reaction happening
at the air/liquid interface. Its slow, and may take a year
for the copper you have to completely corrode away.
You hang the anode plates by pieces of PVC insulated solid
copper wire. The wire can be attached by solder and then
sealed with glue. The glues I've had most success with are
PVC solvent cement or polyurethane sealant. Epoxy can lift
over time.
Alternatively you can drill small holes into the copper
plates a bit larger diameter of the solid wire and use a
center punch and hammer to crimp around the wire.
Commercial platers use titanum mesh baskets and simply
fill them with copper nugets. Or they might use titanium
clamps on solid copper bars.
>
> I of course do not intend to spill a drop. I may will however cover
> the steel with a plastic film or else change to stainless steel or
> such.
Stainless is good around sulfuric acid, but do not have it
permanently immersed. Stainless corrodes slowly when
immersed, but is very resistant to splashes and being wet by
the acid. It has something to do with the dissolved oxygen
from the air maintaining the surface passivation.
Every plating tank I've seen, including mine, will over time
become surrounded by dried salts and plating chemicals
because its very hard to completely avoid splashes and drips.
You should be agitating the plating solution by air bubbles
or motorized PCB motion. A still solution will be limited to
very slow plating rates due to limited copper ion diffusion
at the surface of the PCB. An attempt to plate at normal
current density (1 ~ 2 A/dm^2) in still solution will only
give you rough, and "burned" deposts. Air bubbles are simple
to setup but create fine splashes of copper electrolyte
solution. These splashes must be stopped by some type of lid.
Happy plating.
Adam