I just ran across an article that addresses reliability concerns if moisture
condensation occurs on IC pins with exposed copper.  It doesn't go into great
detail, but did have this statement which concerned me,

 "...sulfer concentrations as low as parts per trillion (PPT) in the
environment will cause copper sulfide to creep on exposed copper on the IC
pins."

If it's a concern on IC pins, it seems logical to me that any exposed copper
areas would be a concern.  This is a different situation than just oxidation
and solderability preservation.

Has anybody heard of this situation or know the extent of this creep?  Any
figures as to what the typical sulfur content is in the atmosphere?

Thanks in advance.

Glenn Pelkey, CQE, CRE
Maxtek Components Corp.

P.S.  Here's the reference if you want to read the whole article:
"Colder Electronic Circuitry is Less Reliable"
Dan Shelikoff
Honeywell
www.iac.honeywell.com/Pub/Journal/journal_sep96/j99624a.htm

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