Silver corrosion on ceramic circuits - what is cause?

[Scubateacher]

Circuit failure after two + years, open circuits. Circuit traces look fine, but there is a top "crust". When I disturbed the crust top, it flakes off, leaving the surface of the ceramic exposed where there is little or no silver left. Some corrosion expects say there is sulfur reacting with the air and moisture. Do lead-acid batteries give off sulfur gas? If not, where does the sulfur come from and what are the acceleration factors?

 

[mcguire]

Sulfur is a corrosive material for silver and lead acid batteries contain sulfuric acid. That looks like a smoking gun to me.

 

[hacksaw]

your description fits what happens with tinned circuit traces. high-humidity will produce the effect that you are seeing.

silver plating is not normally encountered with common electronic circuits.

you need to use tropicalized circuit boards.