[vcf-midatlantic] How to best store vintage ICs

John Heritage john.heritage at gmail.com
Tue Dec 17 18:02:03 EST 2019


Thank you Herb!

It sounds like the black foamed plastics or those pink foamed plastics in a
proper storage crate/box are the way to go... except consider replacing
them every 5-10 years maybe rather than leaving them there 'forever'..

The tubes also work - though you need the right size tubes, and I guess you
can cut them to size to store in smaller containers..

That's my take-away from this :)

On Tue, Dec 17, 2019 at 12:18 PM Herb Johnson via vcf-midatlantic <
vcf-midatlantic at lists.vcfed.org> wrote:

> Henry S. Courbis (and others) suggest "antistatic foam is better than
> nothing" and suggests sealed antistatic bags to store the antistat'ed
> ICs. Also suggested are antistatic IC tubes, which Bill Degnan correctly
> states are superior. But many people (including Henry, myself) end up,
> piling chips in black anti-stat foam "in a shoebox", as he posts.
>
> I'm not ragging on Henry; everyone has these problems and uses the
> solutions reasonably available. Or we inherit collections of chips
> stored this way. Due to my age it's clear to me, these are serious
> problems over a few decades. Since many vintage computers and components
> are 40, 50 or more years old, it's a more serious problem for those
> things.
>
> Some science and engineering of materials comes into play when dealing
> with old IC's and their storage. If such discussions are not of
> interest, stop reading here.
>
> http://www.retrotechnology.com/restore/res_ithaca.html
>
> I don't have a specific Web page, about problems with "black rust" AKA
> "silver oxide". But many have observed that certain TI (Texas
> Instrument) IC's from the 1980's 90's have had IC pins turn black and
> become brittle. In sockets these IC's must be replaced; soldered in they
> seem to mostly perform OK (until they don't). Other ICs in general may
> suffer similar brittle-rust-pin problems. I don't have a factual
> scientific finding on the chemistry of the problem But there's no  doubt
> problems occur for certain runs, brands, and eras of IC's.
>
> Solutions to the old chips that rust-out? one simply avoids them. They
> now stand out with their black and sometimes brittle "legs". My
> expedient (described on the Web page cited) was to use De-Oxit per pin
> and socket and pray.
>
> Antistatic-plastic tubes are available and not overly expensive in bulk.
> One accumulates these or just buys them. Replacement every few decades
> is simply a fact, because they *break up* otherwise. Other than the
> tube's decay, I'm not aware they cause other problems.
>
> I and others have seen chips, stored for decades in antistatic foam,
> fall apart when pulled out. We have all seen such foam become dust or
> mud. So, it's a problem. I'll detail what I know.
>
> I did some research several years ago about the nature of black
> antistatic foam. I had to recover chips stored since the 1970's in black
> foam in a cardboard box; others were packaged in individual little
> hard-plastic containers, also with black foam.
>
> The classic conductive material in these foams, appears to be
> carbon-black. Some carbon-black is produced by burning (with acids I
> believe) *sugar*. Consequently, some resulting carbon black contains
> sugar and acid. Over time and in the presence of oxygen and moisture,
> these contribute to *corrosion*. And over decades, the base material of
> anti-static "foam" degrades, as does almost any plastic. When these
> anti-static foams are cheaply produced, these problems seem to occur
> sooner.
>
> Antistatic foam is intended to be a temporary storage, generally, for
> transport. I'm sure someone with more industrial knowledge, can inform
> me about long-term storage methods. I'm generally aware, those involve
> sealed plastic and antistatic or conductive baggies. There's likely
> other and better (or worse) materials used in storage in recent years.
>
> Among the decades-old ICS, I observed there was much less damage among
> the individual containers than in the "black foam in a box" items. I
> hypothesize that the somewhat sealed containers reduced oxygen and
> moisture exposure. I left those items alone.
>
> The chips stored in sheets of crumbling black foam? As an expedient, I
> repackaged them in "aluminum wool" sheets and sealed anti-stat bags.
> "aluminum wool" is like steel wool, only made from aluminum. It was
> awful, cheaply made, crumbly stuff. But it wont' rust or induce rust in
> other metals, and it provides conductive protection.  Instead of
> 'cardboard boxes" I used acid-free archival boxes. Most cardboard is
> full of acids, from the paper-making process. Again - these choices were
> an expedient of time and cost.
>
> I didn't and don't have cheap solutions to these "black-foam" problems;
> but I've not looked lately. I'm glad the subject came up for discussion
> (if anyone has read this far).
>
> I don't know of a better and relatively cheap material to use as an
> antistatic embedded "pad", than the black (and pink) foamed plastics in
> current use. It seems prudent to replace the foam every several years,
> and to sealed-bag such things: yet I don't follow my own advice out of
> convenience.  Conductive tubes are reasonable for batches of like chips;
> inconvenient for individual chips.
>
> IF somone has factual/engineering data about some modern material
> alternatives, I'd love to hear about it. Don't forget the material facts.
>
> Regards, Herb Johnson
>
>
> --
> Herbert R. Johnson, New Jersey in the USA
> http://www.retrotechnology.com OR .net
> preserve, recover, restore 1970's computing
> email: hjohnson AT retrotechnology DOT com
> or try later herbjohnson AT retrotechnology DOT info
>


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