I'm looking for any reference information/user experience on the
reliability of carbon-ink versus gold used as a switch contact material in
tactile membrane switches.  I searched our company's IEEE/IEC database
(last 10 years) for relevant papers but didn't get any good hits.

Carbon ink over Pb/Sn over Cu has been suggested as "just as good as gold"
for the contacts.  In our application, reliability is the over-riding
concern - we're looking for a contact life of 1 to 2 million actuations and
useable life of 15-20 years.  

We know that meshes and foils are proven EMI shields for membrane switch
assemblies but what about the shielding effectiveness of silver or carbon
inks?  "Just as good as" or worse?

Thanks in advance for your help.

-Gregg
GTE Government Systems Corp
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