But that wasn't the question. You were responding to a comment made in the specific context of gold-on-copper, to the effect that "galvanic reaction" was the reason that such a combination wasn't a good idea. Sorry, but the "galvanic reaction" of dissimilar metals has absolutely nothing to do with the subject at hand.
There actually very often IS another layer (commonly, nickel) placed between a copper conductor and a top protective layer of gold, but this has nothing whatsoever to do with a "galvanic reaction" between these two metals. (If it did, following the original incorrect response on this subject, the problem would then become WORSE due to the fact that there would now be two such interfaces rather than one. Remember, if you can, that the original comment along these lines said that a "galvanic reaction" was a problem between ANY two metals.) The reason that an intermediate layer of nickel is often used in this case has to do with the fact that, left to themselves, gold and copper will tend to diffuse into one another. This causes a problem in electrical applications (where gold-plating copper conductors is being done to prevent corrosion) primarily on the gold side of things, as the copper diffusing up through the gold layer will eventually reach the surface and create the very same corrosion problem that the gold was supposed to be preventing. Nickel doesn't diffuse into gold like copper does, hence its use here.
My, again with the personal attacks; I suppose in the absence of practical knowledge, that's about all one is left with.
Bob M.