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  plus iron , tin and some  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.
 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.
 for soldering iron tips/bits. Prevents the copper bit dissolving in the solder.
 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.
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!
My volume is 2000 Nos. of 100 micron (10mm x 10mm) square article per month.
I tried to get it done locally (Ahmedabad, India), but somehow I could not get professional quality plating here. The article is so delicate (100 micron) that the plating people would bend/deform it due to bad handling.
This article is used as a leaf-spring with a mild spring action (nickel induced) to make a weak electrical contact with a moving gold plated part
Whatever finish is good for a good electrical contact. Or maybe finish is not too important ? I've never thought of the finish part. Qty=2000 per mo.
maybe If I can do nickel myself, then the piece would become hard enough, so that I can get gold done in a shop. That way even if they slightly mis-handle the article, it won't get damaged easily.
Can you please explain this in detail. I cant understand most terms like "anodic cleaning" etc.. I'm more of an electronics guy than a chemical guy. But I guess it shouldn't be too hard to home plate nickel.
Sure, but in English. (Just kidding). Can you explain it in simple steps without figures. Like: "Take a beaker and mix nickel sulphate and whatever..". I'll find out what the above figures mean from a chemistry hand book.
Convince me it has to be made from copper. Convince me it has to be made by edm rather than eg pressing. Then convince me it can't be made by edm of spring steel.
Why not use eg beryllium copper? That's springy. Though I expect spring steel is the actual appropriate material.
What you are asking will almost certainly cost more than a properly designed part - at least ten to a hundred times more - if you do it that way.
Have you thought about eg the cost of fixing the parts in a frame so they can be nickel plated? That costs, a whole lot, each part has to have a good electrical contact too, and your local platers will either charge a whole lot extra for the care involved to do it properly, or they will bend the workpieces.
The alternative is barrel plating, where the pieces are put in a revolving rubber lined barrel and make electrical contact by touching each other from time to time while the barrel revolves, and touching either an electrode with a rubber stem or the outside of the barrel, depending on process.
That's cheap, less than a hundredth of the price, closer to a thousandth or even a ten-thousandth for something your size - but your soft copper pieces will get damaged - but spring steel ones won't.
There may be considerations that I am unaware of, as I do not know all the details of the part and it's intended use, but my simple advice is:
- what you are asking for can be done, and yes I can tell you how to do it, but it would be expensive. Very expensive. Horrendously expensive, outrageously expensive, no-one would even consider doing it that way if they had an alternative
- can you change your requirements a bit? Why does it have to be copper?
Near the copper spring are magnets (for some other purpose) which would impede the motion of the spring if it were made of spring-steel. (I've checked). I don't know breyllium copper.
Edm because I do not want to invest in a pressing die. This die would be expensive since the leaf spring has a peculiar shape with 0.3 mm serrations. Once I'm through selling about few thousand devices, I'll go for a pressing die.
My employees tie them with a thin copper wire (0.2 mm) very carefully, but still those local platers don't handle them with care. And I don't really confide in them because maybe once or twice they might do it with care but I can't really expect them to give me a consistently good quality.
Again, labour is cheap in India, ($10/day for a worker) so tie-ing the pieces is cheaper.
Cu foils are omnipresent. The device works great and is proven. Only that I need consistentcy in plating.
---------------------------------------------------- In my humble opinion the best way to make and plate this part, would be to photo etch the parts out on a +8" x +10" sheet of phos. or beryllium bronze leaving the parts attached at the corners so that the whole sheet can be plated as one and the individual parts can be snapped off as needed. No expensive tooling just a photo neg. of multive parts, no time consuming EDMing and the parts are all connected electrically for easy cleaning and plating.
Don't let the facts interfere with your prejudices