Re: Plastic or ceramic ICs?
No, plastic was very bad for 4000 CMOS logic.
Traces of moisture entered where the plastic was not hermetic with the legs. It dissolved phosphorus traces out of the glass passivation, and the phosphoric acid rotted the aluminium metallisation layers.
Look up 'CMOS purple plague' It's insidious in that it progresses even in stored parts.
DAvid
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Can't afford the volcanic island yet, but the plans for my monorail and the goons' uniforms are done
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