Beware of old AntiStatic foam

[TerraHertz]

'Pin Rot.'

Many IC leads are made of soft iron, not copper. The iron is solder, tin or gold plated after the IC package is complete.  The problem is, gold and tin plating is not hermetic - it is porous. And so some kinds of old chip leads gradually corrode away on the inside, often with no external visible effect. Then you touch the lead (or the board flexes) and because nothing was holding it on but the thin plating, it fractures and falls off. Or remains as a hairline fracture if the IC was soldered into a PCB.

In OP's case, the porous-gold-plated iron legs were in contact with decaying rubber, which produces many chemical breakdown products that are corrosive. Resulting in super-boosted pin rot.

Rather than try to salvage that ruin, maybe better to just find a nice one on ebay and buy it?
I do feel your pain. A lesson learned too late...

I'm currently sorting through and repacking a quite large collection of old ICs that came to me recently. Many of the chips are in anti-static foam, some of which is decaying. But fortunately it's all the 'dry crumbly' type of decay. No corrosion encountered so far. But ALL the foam has to be removed and binned. There are better ways.

[DrG]

This guy does make some nice displays and IC tchotchkes https://chipscapes.com/collections/historical-series

...and you can get another (not as nice) for a not astronomical price https://www.donberg.ie/descript/s/scn_2650.htm

It is interesting to watch the vintage IC market rise over the last decade....makes me a little "thirsty", not enough to get into it so late but I do like to see the history preserved.

The BIN prices that never sell on $bay keep trying to push it harder....lots of boxes and boards and so many chips out there....

[David Hess]

It looks like the pins on these ceramic packages are not part of the leadframe, but separate pieces that are welded(?) to the frame. I hope they are welded, rather than soldered, so that they won't come adrift when I solder them to the socket.

That package is a "side brazed" ceramic package.  The pins are brazed onto the sides of the ceramic package in contrast to a plastic package where the plastic is molded around a lead-frame which holds the semiconductor die and includes the pins which are bent into position.  There is no danger of the pins coming lose from soldering.

Ceramic packages are preferred in high reliability applications because they are hermetically sealed and that extra reliability makes them more suited to expensive semiconductors.

[intabits]

I don't like the direct to board mounting idea ...
either by temperature extremes or the board flexing...
you really don't want to get non-gold alloy solder...
I'd suggest  using a header even if you reject my loose pins idea...

I understand the concerns you raise, though I do struggle to visualize them actually causing problems. The header I envisage is something only about 25-30mm wide, so flexing risk would be low, and only while being (carefully) plugged into the main project board. Storage temperature would be unlikely to range outside 12C to 27C. (But then there is operating temperature)

I like the adapter PCB idea for the more robust external pins and silkscreening for reference, and that could also incorporate the machined socket, or your (probably better) flat sided header idea.

My major concern is to mount the chips once and for all, with no possibility of ever needing to touch them with a soldering iron again. The PCB plus DIP header/socket for the chip, with SIL headers for external connection seems to be the best answer.  I'll get a DIP40 header (may even have one) and see how I feel about using that.

Were there any of the same chips (2650s) nearby but not in the foam and not corroded?

No such luck. I have only two 2650s, and they were the only chips in black foam.

Rather than try to salvage that ruin, maybe better to just find a nice one on ebay and buy it?

Not without at least having a go with what I have.
(and if that failed, I'd probably just drop the whole idea)

This guy does make some nice displays and IC tchotchkes https://chipscapes.com/collections/historical-series

I'm planning an a working, rather than a static demo/display. With leds, hex displays and keypad, etc. Also variable clock speed (2650 can go down to DC), and single stepping.

That package is a "side brazed" ceramic package. 

Brazing - that's would I should have said, something between soldering and welding.

[coppercone2]

check old instruments with cards for this foam shit, they like using it to stabilize the cards from the top to save money on braces

[TerraHertz]

They were stored in a parts draw cabinet. Admittedly, in a room exposed more to the outside air, so with higher humidity.

Ah ha. I think that's the culprit. The foam itself degrades and produces some potentially corrosive substances but it seems they are not very mobile. Moisture multiplies the effect greatly by acting as a solvent and transporter.

Thin gold plating is porous. The underlying metal of the pins is an iron alloy. Without moisture the corrosive substances don't transport into the pores and reach the iron. Moisture alone will make gold plated surfaces on old chips corrode - but it's simple rust that starts in the pores and bubbles off the gold plating.

Add water transporting corrosives into the pores, and the mess in your photos is the result. Very sad.

I'm currently sorting out a quite vast quantity of moderately mixed ICs. It's an old collection, had been in plastic parts drawers in a dry location. Most of the ICs are loose, some in black foam, some al-foil wrapped. They are old enough that some of the loose ones have a dark silver-tarnish appearance to the pins. That's OK, not corrosion. Most are still shiny. Of the ones in black foam _most_ are still fine, but now and then I come across one or two that are a little corroded where in contact with the foam. Some of the foam is very decayed and falls apart into dust.

But so far nothing like your pics. I suspect the differentiating factor was the low humidity storage conditions of this collection.

As I sort them, ALL are ending up in stacks of 20 or less wrapped in alfoil, placed in small yellow paper envelopes in rows in boxes. It's an extremely dense and versatile storage system, easy to keep in good sorted order. The boxes have lids, so it's pest and dust proof.

check old instruments with cards for this foam shit, they like using it to stabilize the cards from the top to save money on braces

That's urethane foam rubber, the bane of restorers of old equipment. It decays to a sticky gunk, falling apart into small pieces that get all through the equipment, and is extremely corrosive to many metals. It's a 'remove on sight' menace.

The black antistatic foam otoh, seems to be something else. Not sure of its composition, other than probably containing a lot of carbon powder additive to make it conductive.

[coppercone2]

are you sure its not that mixed with carbon and freeze dried or something like softee ice cream

[Zero999]

An ultrasonic cleaner is NOT your friend.   The ultrasonic vibrations can break the bonding wires that go between
the chip carrier and the silicon wafer.

Got any evidence to back this up?

Obviously the person who posted doesn't have any evidence and nor do I but, it's plausible ultrasound could damage come components. I belive most DIPs should be fine, as the bond wires will be secured by the encapsulation, but metal can packages might be vulnerable, as well as some crystals and oscillators.

are you sure its not that mixed with carbon and freeze dried or something like softee ice cream

It's a commmon problem. I've seen it on new, old stock, components where I work. I think the old ant-static foam is made of celulose, which produces corrosive decomposition products.

[Ian.M]

The O.P. had a pair of side-braze CERDIP package MCUs.  CERDIPs and other ceramic IC packages will almost invariably have unsupported 'naked' bond wires in the cavity running from the leadframe or leadout metalization to the die.  If the ultrasonic cleaner hits a mechanical resonant frequency of any of the bond wires, failure is highly likely. 

[coppercone2]

you can reduce power level by increasing bath temperature and then dampening it with extra items to make it safer

higher temp = more soap action, it should compensate for the loss due to other materials absorbing energy in the tank

[helius]

Another way of reducing power level in an ultrasonic cleaner is by using beakers suspended inside the tank. There are custom lids to hold them suspended like this. You then hang your delicate parts in the beaker, and the beaker attenuates the vibrations by absorbing some of the energy.

[BILLPOD]

Good Morning Intabits,  I too have ICs stored in antistatic foam that is crumbling, but no corrosion.  How about putting your ICs into some high quality ZIF sockets instead of soldering them?

[Sal Ammoniac]

It's not just anti-static foam that deteriorates, but all foam. I recently dug several of my old HP calculators out of the closet (HP-25, HP-41) and the foam lining in both of the cases had deteriorated and left a black mess on the keyboards of both calculators.

[rdl]

Back in 2004 I bought a sheet of conductive foam from Jameco. The sheet was about 2'x3' and it wasn't cheap. About $30 I think. The plasticky part is shiny and the sheet was very stiff. It didn't bend when held horizontally by one edge. Now, 17 years later it's still fine. I suspect it's made from polyethylene or polypropylene - not some kind of urethane.

[intabits]

How about putting your ICs into some high quality ZIF sockets instead of soldering them?

I'm not sure how you mean to do that.
Most of the pins are corroded away, so there's nothing left to go into any sort of socket.