Homebrew PCBs

boombox666 wrote: 
> 
> I have used the exact same post as basis for my experiment, and I have
> talked with the poster (contacted him directly).
> 
> I have found some patents on electrolytic production of persulfates:

The patent i found is very difficult for me to read. Not easy for a
chemistry ignorant and non English speaker. 

Thanks for posting yours findings. I get that ammonium persulfate
regeneration can be done, sodium persulfate is in the very difficult
area. Can be done by special setup and additives. Is required high
currents, controlled temperature and have low efficiency (water
hydrolysis and anode waste). Is written that adding crazy things make it
possible, and 4% ammonium persulfate can give some efficiency for what
we both want.

> My first setup was basically partially spent sodium persulfate etching
> solution, a small platinum electrode and a piece of circuit board as
> the copper. The reason for the failure is the absence of sulfuric acid
> that needs to be there in the solution as a starter.
> For the constant current power supply I use a small mc34063 switcher
> in constant current step down mode with a potmeter to adjust the
> current.

You seem to use very low currents. Both the anode and the psu seem short
for the application. That anode has very small area. Just guessing but
seems difficult getting 5A without surpass the maximum anode current
density. And the thing should work better if used during etch. 

> 
> The platinum electrode can be gotten at this ebay shop for cheap. It
> is a bit small, but usable.

Is the same anode i looked, when thought of this! And the seller
continuous to sell cyanide gold electroplating stuff! I wonder how it be
in customs: "Ohh thats not drugs, i never buy such thing, it's super
poisonous cyanide!"

I believe that a large pure titanium sheet, in such low concentration of
acid, should do for anode. Large enough for a low current density. But
the patents say 33-100A sq dm, the titanium shouldn't go much upper than
5....

The titanium is the way i intent to go in the pulsed copper plating,
with redox additive. And using eBay 'Mean Well' Chinese branded PSUs. I
have 2 for other things and both have a DC side pwm controller with
current sensing included. It looks simple to modify with potmeters (and
better than Markus Zingg light dimmer on AC).


> As soon I know more I will post it here.

Thanks i appreciate it. But be aware that such slow etchant can't worth
much time and cost.

> 
> Thank you so much for the big post. I am looking into copper plating
> solder wire to create the solder filled eyelets at home.
> 
> The reason I do not go with trough hole plating baths is mostly the
> price and the space to maintain baths.

That copper plated solder don't seems easier than solder wires through.
And don't invent things for brightener! Go with a simple bath, high acid
or one the alkaline setups.  Better just use CuSO4 and your platinum
anode in low current. 

The plating setup is not a elephant :> Can be placed in one shelf. May
need to remove/move other shelf stand if not between-stands enough
hight, the space of one stand for the tanks and the upper space for
moving boards around. The only problem with it is if chemistry
maintenance is necessary, thats why i try choose it wisely. The copper
plating bath (the most tricky) could give good enough results without
additives in the setup i wrote about before.

If one don't go to bungard or mega the chemistry prices start at 300eur
for 5L tanks and half is enough. It's not much compared to building the
setup that cost about 500eur. Anyway I have that value thought for setup
and chemistry...


Sim�o