DEC quad board rack

[Michael Zahorik]

Thanks for responding. Makes sense. I do like your wood working. I may give it a try. Should not be very difficult. 
 Mike Zahorik (414) 254-6768

      From: Noel Chiappa via cctalk <cctalk at classiccmp.org>
 To: cctalk at classiccmp.org 
Cc: jnc at mercury.lcs.mit.edu
 Sent: Sunday, December 31, 2017 7:05 PM
 Subject: Re: DEC quad board rack
   
    > From: Michael Zahorik

    > a dozen or so spare boards for my PDP8E. I was wondering about how to
    > store them. Some guys recommend some poly bags, others say it is
    > important to protect against humidity. ... have you had any failures
    > while in storage?

Well, i) most of my boards had been in uncertain storage for a long time
before they got to me, and I've only tested a fraction of them, so if I tried
one now, and it had an issue, I wouldn't know when (i.e. under which storage
regime) it happened - some have shown failures, but I think they all happened
before they got to me; ii) some of the failures we see (e.g. PROM's losing
their programming) are known to happen via various time-related processes,
not storage condition; and iii) I'm not a hardware person, but even then,
you'd want someone with expertise in failures, which is not common.

But, having said that, these are my 'common-sense' rules for storage: i) bags
aren't critical (especially for older stuff, which is generally bipolar, not
CMOS, and therefore not very sensitive to static), ii) high humidity is not
good, as you can get corrosion on chip leads (I've seen a few where the leads
were so corroded they came off)- but very low humidity can be an issue, if
you have CMOS, as it's more static-friendly (as Dave Bridgham found out the
hard way in his lab); iii) large-amplitude temperature cycles are not good,
as thermally-induced contraction and expansion probably aren't good; and
avoiding very high, and very low temperatures (even if constant) is probably
better for long-term health.

    Noel