siliconmike wrote:

I'd like to learn how to do electrolytic nickel and gold plating on
copper sheets. Any web resources/links etc. ? I tried to search on
google but almost all results were commercial companies.

My exact application is to
1. edm wire cut copper foil (100 microns) - about 10mm x 10mm piece
2. clean off the corrosion on the edges due to wire cut process
3. nickel plate and make total thickness 130 microns
4. gold plate about 2 microns.

(I'm not sure whether I need to do step 2).

You do, but it's just part of the process and nothing special. You'll
probably have to polish and you definitely have to clean the copper before
nickel plating anyway.


Nickel plating is not too difficult, but good gold plating requires using
cyanide - could you send off for the gold plating? Unless you are doing a
lot, it will be easier. Much easier.

Mind, the gold plating shop will usually also do better polishing and nickel
plating than you can, as they have the experience and the large volume tanks
(volume makes a difference, maybe it shouldn't but it definitely does).


No, I need to know more about what you want to do. First impression, for a
gold plated copper foil square, get it done rather than do it yourself. You
can probably buy gold plated copper foil anyway. But I expect it's a bit
more complex than that ...



What is the final finish required? Rough, dull, matt, satin, bright, mirror?
'Cos that's where you decide where to start. Ooops, I forgot the very first
question, how many?





I can do (and have done) nickel, NiCo, NiCu, NiFe, NiCoFe*, NiCrCoFe*,
copper, copper/tin and copper/nickel electroforming, and all those [1] plus
iron [2], tin and some [3] silver plating, but not gold - this may be partly
because it's almost impossible to get cyanide here in the UK. However if I
really wanted to I probably could get cyanide, so it may also be partly
because I simply don't want to work with cyanide, and I'm just using the
difficulty as an excuse ... I don't know how hard it is to get cyanide in
the US (where I presume you are located).


* proprietary to me. Don't ask unless you have overflowing pockets.

[1] depending on substrate. Eg acid copper doesn't work well on ferrous for
example, and I don't do cyanide copper, the usual alternative - but I can
plate copper on _some_ ferrous metals without using cyanide. It's tricky.

[2] for soldering iron tips/bits. Prevents the copper bit dissolving in the
solder.

[3] again depends on substrate, though I can do silver on most substrates
(and I am hopefully adding direct silver on stainless to the list next week,
fingers crossed xxxxxx)

(
though you can silver plate over nickel, and you can use a strike coat of
nickel over stainless - iirc it's just nickel suplhate and sulphuric acid, a
bit more dilute than eg Watts nickel with a bit more current and a bit
hotter -let me look it up.

here we go -
clean, etch in 30% room temperature sulphuric acid for 3 minutes at 3
A/Dm^2 for 2-3 minutes anodic followed by 6 minutes cathodic. It is
advisable to use two tanks, one for the anodic and one for the cathodic
cleaning, to prevent Cr and Fe buildup.

Plate in:

250 g/l nickel sulphate
commercial sulphuric acid 25 ml/l
- weight equivalent 50 g/l

16-22 A/dm^2, 30-40 C, for 5-10 minutes. sg 1.160. One nickel anode,
remaining anodes chemical lead.


It that the kind of advice you are looking for?
)







BTW, a lot of hands-on how-to-do-it plating know-how is (or was) considered
semi-secret, a kind of trade secret, like you only pass it on to an
apprentice, and it's hard to find - old craft plating workers you can get to
treat you as an apprentice are best, and old books are second best. There is
a small body of scientific literature, but that secrecy makes it not too
useful. Apparently the Russians didn't have that mentality, and their
literature has lots of stuff - unfortunately, I can't speak Russian!

At least that's my impression.


--
Peter Fairbrother