General > General Technical Chat
Beware of old AntiStatic foam
intabits:
Thanks for the responses.
Good idea about stabilizing the pins while soldering.
So far, I have only applied some Deoxit, and the black munge then seems to scrape off fairly easily.
Next, I'll use IPA and a toothbrush (if I had a girlfriend, I'd use hers) to get the munge off.
I'll try the eraser idea on any stubborn spots.
"Wait are those pins just corroded or did the thin pin big disappear completely?"
Not sure what you mean there, but most of the pins are definitely very, very corroded.
Do people agree that soldering to a socket as shown is the best way to make these devices usable again?
(I'll first test a socket to make sure the pin tops take solder well - might have to remove some plating if not)
DrG:
--- Quote from: intabits on March 21, 2021, 05:35:13 pm ---Thanks for the responses.
Good idea about stabilizing the pins while soldering.
So far, I have only applied some Deoxit, and the black munge then seems to scrape off fairly easily.
Next, I'll use IPA and a toothbrush (if I had a girlfriend, I'd use hers) to get the munge off.
I'll try the eraser idea on any stubborn spots.
"Wait are those pins just corroded or did the thin pin big disappear completely?"
Not sure what you mean there, but most of the pins are definitely very, very corroded.
Do people agree that soldering to a socket as shown is the best way to make these devices usable again?
--- End quote ---
I saw this once, with a couple of chips that were in a plastic drawer - but only a couple of chips were affected. I am sorry that I can't remember precisely, but I don't think they were on static foam at all - If they were, I do not remember it being all degraded.
It puzzled me as to why a few chips would get corroded when others stored in the same environment did not. To be clear, I think you are on solid ground suspecting the degraded foam, but I just don't know.
Mine were in worse shape and portions of some pins were gone:
For the heck of it, I kludged the IC onto a socket and it did still work https://www.eevblog.com/forum/vintage-computing/sn76489-reincarnation/msg2989066/#msg2989066
Personally, if I had some ICs that were extremely valuable to me, I think I would treat the pins with something like 99% isopropyl alcohol or ethanol, to remove any corrosive chemicals that might be on the pins, and store them in a plastic tube. But I don't know this for a fact. For example, in numismatics people used to use certain kind of soft PVC "flips" until learning that they could interact and damage the coins - that is well known now.
If some one has some hard facts or "museum curator"-type practices, I would like to know also.
Edited to add: The ICs had been in the plastic drawer for 30+ years.
tooki:
--- Quote from: intabits on March 21, 2021, 11:44:49 am ---Unforunately, I wasn't aware of this previously, and maybe others aren't also...
Among my most prized possions are my first two microprocessors - a pair of Signetics 2650s with ceramic packages and gold plated pins, that I bought new back in 1976.
I dug them out a few months ago, just to make sure that they hadn't been lost, but I didn't take a closer look at them until today.
Not only had the antistatic foam they had been stored in for 40+ years decayed to dust, it had corroded the pins of the chips away in the process. The gold plating was no obstacle.
I found some discussion of this:-
https://vintage-radio.net/forum/showthread.php?t=131907
So to save them, (after DeOxiting and cleaning them) I'm thinking of soldering them to machined pin IC sockets like this:-
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.
Before I do this, does anyone here have any better suggestions for saving these chips?
A PCB adapter board with header pins maybe? (they don't need to be plugged into any existing socket, so the pinout can be anything)
--- End quote ---
Oh dear, that’s rough!! :(
At work, the component drawers are full of foam that’s decaying, but there’s no apparent corrosion. What were these chips, and their foam, stored in, and under what conditions? I suspect that there are additional factors beyond age that come into play to cause this level of catastrophic corrosion.
magic:
Beware that inserting the bottom pins of a female socket into another female socket will ruin the latter.
I would look for a similar frame with real male pins (if such things even exist) or create one by transplanting pins. Half an hour of boring work and you're in. Well, all of that assuming that the ICs are ever meant to be used.
drussell:
--- Quote from: intabits on March 21, 2021, 05:35:13 pm ---Do people agree that soldering to a socket as shown is the best way to make these devices usable again?
--- End quote ---
Too bad you don't have access to whatever apparatus the Chinese recyclers use to weld on and polish up new pins on salvaged components when they sell all those cleaned and refurbished, sometimes remarked, sometimes even fake chips. :)
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