I stumbled upon the following article while trying to identify some old RAM modules:


In the article, it mentions the following about gold contacts:

A note about contact metals

Chip contacts are either gold- or tin-plated. I recommend chips with gold contacts because they don’t corrode. Also, never insert tin-plated chips into gold-plated sockets. Different metals will increase the likelihood of corrosion.

I don't understand how gold cannot corrode on it's own, yet cause another dissimilar metal such as tin to corrode. Is this article correct?

  • 2
    $\begingroup$ Yes, that's a pretty well-known thing in chemistry. $\endgroup$ Mar 27 '19 at 21:14
  • $\begingroup$ Yes, but how? There has to be some kind of ion exchange between gold and tin correct? $\endgroup$
    – user148298
    Mar 27 '19 at 21:16
  • $\begingroup$ No. But there is an electron exchange between the two, that's for sure. $\endgroup$ Mar 27 '19 at 21:36
  • $\begingroup$ Speculation: Gold has no protective oxide layer, so at least one electrode of the cell is freely accessible for any ion that comes along to discharge. $\endgroup$
    – Karl
    Mar 27 '19 at 22:41

First off, read carefully:

Different metals will increase the likelihood of corrosion.

It doesn't say:

Different metals will increase the likelihood of corrosion of gold

With that in mind, it's called galvanic corrosion and occurs when contact between two (or more) dissimilar metals causes the more reactive one to corrode when it normally would not have or faster than it would on its own. This action is similar to a galvanic pile (though its only one cell) that has short circuited thus corroding the more reactive metal.

In your case it is definately the tin that will be corroded, not the gold as tin is more reactive.


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