AVR-Chat

> Silver alloys are fine for "power" applications but they're severely
> limited when you get down in the mud with really low currents because
> the contacts will build up an oxide or a sulfide coating.  This is why
> they depend on the small amount of arcing that will occur in a power
> circuit.  At low currents, such as driving a logic input, you'll need
> gold inlay or a gold flask over silver contacts.  The same holds true
> for relays.  Be sure to9 look at the minimum current ratings for
> switching devices.  There's also a difference between switching current
> and carrying current capacities.
>

It's called "wetting current" and even gold-on-gold needs some small current.
Litton made that mistake with their first shock sensors for glass break.
The switches would stay closed for hours or days or weeks, then open
up for a few seconds for no apparent reason.