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Re: Removal Suggestions? - Black Antistatic Residue from the 70's

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  • Mike
    Goo Gone did wonders removing some disintegrating foam insulation from an Apple Imagewriter printer i recently did some restoration work on. It still took
    Message 1 of 8 , Nov 16, 2012
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      "Goo Gone" did wonders removing some disintegrating foam insulation from an Apple Imagewriter printer i recently did some restoration work on. It still took some mechanical effort, so I'm not so sure how it would work in your case with IC pins.

      Regards,
      Mike Willegal

      --- In midatlanticretro@yahoogroups.com, Burning Image <visual_storytellers@...> wrote:
      >
      > I recently managed to find a NIB computer kit that arrived in today's mail.  After carefully opening it, I noticed the 6800, 6821 and 6811 chips were sitting on pads of black antistatic foam.  Flashing back a couple decades, I thought about an 1861 chip that had its pins eaten by this stuff.
      >
      > I managed to get the chips out of the crumbling material, but some of it is still clinging to several pins.  As it already managed to devour the gold plating on some pins, I don't want to apply too much pressure to remove the remaining residue.
      >
      > Any suggestions on how to clean the pins?  It doesn't appear to be water soluble.  
      >
      > TNX!
      >
      > Cory - WA3UVV
      >
    • Mr Ian Primus
      ... Even if they do break off flush with the IC body, it s possible to chisel away at the plastic package to get enough of the lead exposed to solder to.
      Message 2 of 8 , Nov 16, 2012
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        --- On Fri, 11/16/12, Systems Glitch <systems.glitch@...> wrote:

        > If they do break off, and they're ceramic side-brazed
        > packages, I usually solder them into a machine pin socket.
        > Use a lot of water-soluble flux and wash well. You can do
        > the same with plastic DIP packages as long as the pins don't
        > break off flush with the IC body.

        Even if they do break off flush with the IC body, it's possible to chisel away at the plastic package to get enough of the lead exposed to solder to. Remember that the die of the chip is just in the very center, the rest of the package is just leadframe. You can chisel into it quite a bit.

        That foam is evil and corrosive - I don't have any specific hints for removing it, but something I've had a lot more experience with is tarnished IC legs. Some chips (especially the Namco customs from 80's era arcade games) have legs that will tarnish and blacken, and get very brittle and crumble off. Sometimes even flush with the package (and then you have to do the above). But the black tarnish isn't conductive, and doesn't even take solder well, so it has to be removed. In this case, Tarn-X does a fantastic job dissolving it. Be sure to clean it again with isopropyl alcohol to get the Tarn-X off, it's a pretty nasty chemical. Smells awful too.

        TI branded logic from the 70's has a very similar problem, but in that case it's just standard TTL and not worth the effort to salvage.

        -Ian
      • s100doctor
        ... Another description is polyolefin plastic resins ; LDPE (low density polyethylene); EVA (Ethylene-vinyl acetate). I ve heard rumors that the
        Message 3 of 8 , Nov 16, 2012
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          > --- In midatlanticretro@yahoogroups.com, Burning Image <visual_storytellers@> wrote:

          >..., I noticed the 6800, 6821 and 6811 chips were sitting on pads of black antistatic foam.
          > > I managed to get the chips out of the crumbling material, but some of it is still clinging to several pins.  As it already managed to devour the gold plating on some pins, I don't want to apply too much pressure to remove the remaining residue.
          > >
          > > Any suggestions on how to clean the pins?  It doesn't appear to be water soluble.  

          --- In midatlanticretro@yahoogroups.com, "Mike" <mike@...> wrote:
          >
          > "Goo Gone" did wonders removing some disintegrating foam insulation from an Apple Imagewriter printer i recently did some restoration work on. It still took some mechanical effort, so I'm not so sure how it would work in your case with IC pins.
          >
          > Regards,
          > Mike Willegal

          I'm working up an analysis of this black antistatic foam stuff. There's many reports of damaged chips from the degradation of this material. I want my site to get on top of this. I don't have a document ready to publish, but here's some bits of information:

          > This patent application for antistatic foam looks more reasonable.
          > http://www.google.com/patents/US5567740
          > Here's an excerpt:
          >
          > "This foam is produced by combining conventional polyurethane foam-forming
          > reactants and an effective amount of an antistatic agent such as
          > tetracyanoquinodimethane (TCNQ) or sodium perchlorate under foam-forming
          > conditions. In one preferred embodiment, the conductive foam is
          > subsequently reticulated by momentary exposure to a flame front."

          Another description is "polyolefin plastic resins"; "LDPE" (low density polyethylene); "EVA" (Ethylene-vinyl acetate). I've heard rumors that the conducting content is lamp black, burned sugar (acid not heat). There's likely many ways this stuff is/was produced.

          If the base material is a kind of plastic, then something like "Goo Gone" - in large part made of toluene - may dissolve it. Also: the traditional "gag" at an auto shop is to ask the new guy/gal to carry gasoline in a styrofoam cup. Of course, it dissolves the cup FAST.

          Handle these flammable and liver-damaging substances with caution. Please report results here, and with permission I'll quote content posted accordingly.

          Herb Johnson
        • Systems Glitch
          I ve been told by someone who worked in the industry back then that the good stuff was synthetic foam with lamp black/carbon/graphite/et c., but that the
          Message 4 of 8 , Nov 16, 2012
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            I've been told by someone who worked in the industry "back then" that the good stuff was synthetic foam with lamp black/carbon/graphite/et c., but that the lousy stuff was just sugar reduced to carbon with fuming sulphuric acid and sliced into sheets. The foam was, of course, washed after production, but presumably some of the acid remained. Fuming sulphuric acid would be 98% or higher concentration (it's hydroscopic, so hard to keep it above that).

            One can try the sulphuric acid reduction at home with table sugar and sulphuric acid drain opener. It proceeds slower than if one uses fuming acid. It does indeed make a carbon foam, which like the foam that dissolves component leads, squishes and does not return to its original shape/thickness. Essentially the sulphuric acid, which is a very good dessicant at high concentrations, strips the hydrogen and oxygen from sugar as water, leaving only the carbon. Steam is created as the reaction heats up, resulting in foaming.

            Forrest M. Mims, III also claims that the black foam is made with carbon in one of his "Engineer's Mini-Notebooks." There is a project that involves building load cells for sensing pressure with a bit of carbon antistatic foam sandwiched between two pennies in a piece of plastic tube. The further compressed, the less resistance.

            Thanks,
            Jonathan

            On Sat, 17 Nov 2012 00:37:50 -0000
            "s100doctor" <hjohnson@...> wrote:

            > > --- In midatlanticretro@yahoogroups.com, Burning Image <visual_storytellers@> wrote:
            >
            > >..., I noticed the 6800, 6821 and 6811 chips were sitting on pads of black antistatic foam.
            > > > I managed to get the chips out of the crumbling material, but some of it is still clinging to several pins.  As it already managed to devour the gold plating on some pins, I don't want to apply too much pressure to remove the remaining residue.
            > > >
            > > > Any suggestions on how to clean the pins?  It doesn't appear to be water soluble.  
            >
            > --- In midatlanticretro@yahoogroups.com, "Mike" <mike@...> wrote:
            > >
            > > "Goo Gone" did wonders removing some disintegrating foam insulation from an Apple Imagewriter printer i recently did some restoration work on. It still took some mechanical effort, so I'm not so sure how it would work in your case with IC pins.
            > >
            > > Regards,
            > > Mike Willegal
            >
            > I'm working up an analysis of this black antistatic foam stuff. There's many reports of damaged chips from the degradation of this material. I want my site to get on top of this. I don't have a document ready to publish, but here's some bits of information:
            >
            > > This patent application for antistatic foam looks more reasonable.
            > > http://www.google.com/patents/US5567740
            > > Here's an excerpt:
            > >
            > > "This foam is produced by combining conventional polyurethane foam-forming
            > > reactants and an effective amount of an antistatic agent such as
            > > tetracyanoquinodimethane (TCNQ) or sodium perchlorate under foam-forming
            > > conditions. In one preferred embodiment, the conductive foam is
            > > subsequently reticulated by momentary exposure to a flame front."
            >
            > Another description is "polyolefin plastic resins"; "LDPE" (low density polyethylene); "EVA" (Ethylene-vinyl acetate). I've heard rumors that the conducting content is lamp black, burned sugar (acid not heat). There's likely many ways this stuff is/was produced.
            >
            > If the base material is a kind of plastic, then something like "Goo Gone" - in large part made of toluene - may dissolve it. Also: the traditional "gag" at an auto shop is to ask the new guy/gal to carry gasoline in a styrofoam cup. Of course, it dissolves the cup FAST.
            >
            > Handle these flammable and liver-damaging substances with caution. Please report results here, and with permission I'll quote content posted accordingly.
            >
            > Herb Johnson
            >
            >
            >
            >
            >
            > ------------------------------------
            >
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            >
            >
            >
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