Larry Battraw wrote:
>
> This sounds very interesting since you've had actual experience using
> these types of chemistries.
Experience only with comercial palladium just like the one Markus Zingg
bought. In a commercial machine for small runs during some months. With
horrific documentation.
> Posting the recipe
> for anything is always informative even if homebrew people can't
> always get the same ingredients needed.
I have posted it before... I prefer to have my results before saying how
i managed to get the not easy to figure what are and where to get stuff.
For personal reasons it will take time.
>
> Are you talking about covering a board with graphite powder and then
> drilling the holes, such that the powder falls in and coats the
> hole-walls as they are drilled? It's not clear exactly what is going
> on, as you also talk about "graphite chemistry". Please let us know a
> little bit more about how this is done.
>
You are right, i re-read my previous email and my english is really bad
i didn't got to make myself understood.
I was saying that you drill the pcb in a drill press normally, but under
the pcb exists graphite powder. The drill bit must enter deep in the
powder and let it spread on the hole surface upwards.
I referred graphite chemistry in comparison with carbon black to express
how conductive it is, nothing else, not to use the chemistry based on
it.
Ohh and of course (i always skip the obvious parts) it must be copper
plated after such mechanical activation. Suppressor additive is not
difficult to source as pure chemical (i got enough for 830liters for
14eur IIRC), and it should really help on this.
> Thanks for the detail you've given on this. I figured using something
> like an H-bridge with MOSFETs would do it but it sounds like it's more
> involved if you have to use reverse voltages that are different than
> the positive plating voltage. Have you had any success doing this
> type of plating or has it not worked out very well? What are some of
> the problems you've run into?
You need big currents. Say 50 up to 100A in direct mode (3 times for
reverse) for a 200x300mm (~100inch) board. Such circuit isn't easy and i
never did anything similar... It seams an AC TIG welder... Other than
that is the required voltage for the reverse pulse no matter how many
hairs i pull off i just can't figure it out, it will be found by
testing.
Simao