[time-nuts] Anti-Static conductive foam warning
Apologies to those who might see this on more than one group or list and apologies again if it's old news to everyone but me, but I did think it important enough to share. I've just retrieved a pair of ICs that have been dry stored as spares in a component storage rack since 1979, a long time I know but probably not unusual for those of us using and maintaining older equipment. These, as I thought anyway, were correctly stored with the pins pressed into black anti-static foam, the usual stuff that's been used for this purpose for years. Unfortunately the foam has broken down into a sticky crumble and the plating on the IC pins is quite badly corroded, probably to the point where they won't take solder. A metal canned crystal lying against the foam has also corroded at the pont of contact. I've seen this stuff turn into a gooey mess inside some instrument cases but hadn't previously even thought about the same thing happening where it's used used for component storage. I've checked other trays and whilst not too many used this stuff but where they did there's evidence of similar problems. I've even got a later large component rack, all ok so far but for how long?, where it was fitted from new to every drawer:-( That's all, just offered as a word of warning to anyone else with components similarly stored. regards Nigel GM8PZR ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Anti-Static conductive foam warning
Hi Nigel I've seen this happen in some other circumstances too, and one of the worst ones was for VNA Cal kits. It really makes a mess, and it's pretty hard to clean up. I'm wondering if anyone else who's seen this problem has some advice on a good way to restore the items. It does seem that there are several types of foam (and rubber for that matter) Daun -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of [EMAIL PROTECTED] Sent: Thursday, July 24, 2008 1:12 PM To: time-nuts@febo.com Subject: [time-nuts] Anti-Static conductive foam warning Apologies to those who might see this on more than one group or list and apologies again if it's old news to everyone but me, but I did think it important enough to share. I've just retrieved a pair of ICs that have been dry stored as spares in a component storage rack since 1979, a long time I know but probably not unusual for those of us using and maintaining older equipment. These, as I thought anyway, were correctly stored with the pins pressed into black anti-static foam, the usual stuff that's been used for this purpose for years. Unfortunately the foam has broken down into a sticky crumble and the plating on the IC pins is quite badly corroded, probably to the point where they won't take solder. A metal canned crystal lying against the foam has also corroded at the pont of contact. I've seen this stuff turn into a gooey mess inside some instrument cases but hadn't previously even thought about the same thing happening where it's used used for component storage. I've checked other trays and whilst not too many used this stuff but where they did there's evidence of similar problems. I've even got a later large component rack, all ok so far but for how long?, where it was fitted from new to every drawer:-( That's all, just offered as a word of warning to anyone else with components similarly stored. regards Nigel GM8PZR ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Anti-Static conductive foam warning
The turning into goo is called reversion, and is a property of some kinds of polyurethane. There is a good explanation in US patent 4040991, and in www.wolaa.org/files/Spring_2007_OHS_-_WOL_In-house_Expertise.pdf . It can be difficult to find a solvent for the goo. As for corrosion causing unsolderability, there is a draconian solution. It was a classic story from the 1970s. We were getting a demo ready for a show, and it turned out that the leads on the Nixie tubes had corroded enough that they would not take solder. This is Sunday afternoon. What to do? I dipped them in dilute sulfuric acid (battery acid cut 3:1), rinsed them off in hot water, and then had no problem soldering. The acid dip did not cause subsequent problems, although one could have also used dilute bicarbonate of soda to neutralize any traces of acid that survived the hot rinse. Joe Gwinn [EMAIL PROTECTED] wrote on 07/24/2008 01:38:45 PM: Hi Nigel I've seen this happen in some other circumstances too, and one of the worst ones was for VNA Cal kits. It really makes a mess, and it's pretty hard to clean up. I'm wondering if anyone else who's seen this problem has some advice on a good way to restore the items. It does seem that there are several types of foam (and rubber for that matter) Daun -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of [EMAIL PROTECTED] Sent: Thursday, July 24, 2008 1:12 PM To: time-nuts@febo.com Subject: [time-nuts] Anti-Static conductive foam warning Apologies to those who might see this on more than one group or list and apologies again if it's old news to everyone but me, but I did think it important enough to share. I've just retrieved a pair of ICs that have been dry stored as spares in a component storage rack since 1979, a long time I know but probably not unusual for those of us using and maintaining older equipment. These, as I thought anyway, were correctly stored with the pins pressed into black anti-static foam, the usual stuff that's been used for this purpose for years. Unfortunately the foam has broken down into a sticky crumble and the plating on the IC pins is quite badly corroded, probably to the point where they won't take solder. A metal canned crystal lying against the foam has also corroded at the pont of contact. I've seen this stuff turn into a gooey mess inside some instrument cases but hadn't previously even thought about the same thing happening where it's used used for component storage. I've checked other trays and whilst not too many used this stuff but where they did there's evidence of similar problems. I've even got a later large component rack, all ok so far but for how long?, where it was fitted from new to every drawer:-( That's all, just offered as a word of warning to anyone else with components similarly stored. regards Nigel GM8PZR ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi- bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Anti-Static conductive foam warning
Hi Daun Nigel, I've experienced the same problem, for example with sliding loads, cal kits and other accessories. The trick is to remove all the foam *before* the damage is done. Once the deteriorating foam turns to sticky crumble and reacts with the precision plated metal surfaces in these kits, the surfaces can actually become physically pitted and discolored. I could kick myself for not staying on top of this and removing the foam sooner in some instances. Next question: Are the manufacturers listening? Or are they still using the same foam (that will de-compose in 15 or 20 years). Greg Daun wrote: --clip-- I'm wondering if anyone else who's seen this problem has some advice on a good way to restore the items. --clip-- ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
