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Old 23rd Feb 2021, 3:42 am   #5
Keith956's Avatar
Join Date: Jun 2019
Location: Near Thame, Oxfordshire.
Posts: 333
Default Re: Plastic or ceramic ICs?

Originally Posted by Radio Wrangler View Post
Look up 'CMOS purple plague' It's insidious in that it progresses even in stored parts.

Hi David,

My memory is not as good as it was but I recall that 'purple plague' was an issue caused by the formation of a weak Au / Al alloy in the wire bonding process (bond wires were originally gold, the pad metal aluminium), not by moisture. When the aluminium bondwire process was mastered the problem went away.

But yes plastic was generally less reliable and hence ceramic preferred for mil spec parts.

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