Anyone ever had any negative experiences with mounting nickel plated connectors to an aluminum chassis.

We're using Nickel plated composite connectors (D38999/20M) against 5541, Type II, Class 3 coated sheet aluminum and having to meet 2.5 mohms or less of bond resistance.

I've been through plenty of bond resistance wars and I'm particularly concerned with the galvanic couple of Aluminum and Nickel especially since we're not sealing the interface and having to go through salt fog testing as part of our qualification.  We must maintain less that 5 mohms after salt fog exposure without re-torqueing screws, which seems to be the common hidden factory way of sweeping the problem under the rug.

I've been told we have lots of experience with silver colored connectors in aluminum housings, but a further look-see shows all those connectors are actually Cadmium over Nickel plating which is a much nicer galvanic match.

If this is truly a risk, then our options appear to be:

1. Seal the interface with a conductive gasket (the interface is inaccessible for a goop application sealing)
2. Plate the Aluminum with Nickel to eliminate dissimilar metals
3. Use a washer of intermediate material to reduce the galvanic span

Are there other suggestions or experiences anyone can relate?

Thanks,

Gregg

Gregg Temkin
Principal Manufacturing Engineer
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