Gold plated Edge connector tabs

I had put this in a previous thread but it wasn't directly connected to that thread so here it is separated out.

We often get PWB's fabricated with a gold plated edge connector tab. These are standard 0.062" FR4, however we have not ever given any specs to the fabricator regarding the gold plating - all we say is "gold plate this area". (I know, I know, sloppy...) I would like to add a spec into our files for this so it is better controlled.

So I asked one of the fab houses we use what they do when we ask for gold plating. He said they nickel plate 50-75 microns and then gold plate hard gold onto that, 15-25 microns. I found these numbers incredibly high, according to some values given by Dave for the number of insertions a given thickness is capable of, when I converted them into micro-inches. 50 microns is almost 0.002" of nickel, and 15microns is almost 600 microinches.

According to the following numbers:

"The experiment was to determine insertions from a gold plated board into a connector. Same thickness boards (0.062"), with 100 m base nickel. � 100m gold => 500 insertions � 50 m gold => 300 insertions � 30 m gold => 50 to 75 insertions � 20 m gold => 10 insertions. " Dave stated that the 'm' referred to micro-inches.

I could probably insert this board 1000's of times without a problem. Am I missing something here? Do you see an error in my calculations or is the above info really referring to microns? I can't see a fab house doing way more than they need to when given no guidelines. Human nature tends more to doing the minimum possible... Do you think the fab house really means micro-inches? I asked them, but they insisted it was microns.

Regards,

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