Anti-static foam / IC storage

Discussion in 'General Electronics Chat' started by DigitalReaper, Aug 9, 2010.

  1. DigitalReaper

    Thread Starter Member

    Aug 7, 2010
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    I've got a couple of pink sheets of foam that came with motherboards and some black blocks of stuff that came with a graphics card. I've tested them with a multimeter but they don't seem to be even remotely conductive, are these anti-static packaging or just padding?

    What i'm really looking for is a way to store my ICs, at the moment I have to be really careful not to spill them (they're still in the anti-static tubes used for shipping). I was planning to stick them into anti-static foam, but maybe there's a better way?
     
  2. mcgyvr

    AAC Fanatic!

    Oct 15, 2009
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    A typical multimeter will not work. You need a surface resistivity meter.
     
  3. marshallf3

    Well-Known Member

    Jul 26, 2010
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    The stiff black stuff is conductive foam and can usually be measured with a meter on the 20 Mohm scale. The thin pink stuff just has a dissipative coating on it that doesn't really measure out in ohms/cm or anything.

    Aside from some of the really early CMOS stuff I'm not too worried about static damage, most everything nowadays has greatly improved integral protection and by habit I keep a hand on a decent ground or the chassis of something anyway.

    If working inside I am big on staticide in the winter though. I've got a gallon jug of concentrate, just an ounce mixed into a spray bottle of water treats a large area for a month by simply misting it around the room and letting it settle on the floor.
     
  4. DigitalReaper

    Thread Starter Member

    Aug 7, 2010
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    I've tried to measure the resistance of the black foam but I can't get a reading, even on the 200 Mohm setting. To measure I pinched 2 or 3mm of foam between the probes and pressed them together fairly hard.

    Is it safe to store the chips bare in a plastic box if i'm using one of those anti-static wrist straps?
     
  5. Wendy

    Moderator

    Mar 24, 2008
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    I use standard black conductive foam (about ½" thick) for my ICs, and put them in plastic kit boxes. It is not the best, but it works. The kit box plastic is a major ESD generator. Never store ICs in bare plastic.

    The tubes are the best protection you can have, both mechanically and electrically.

    You can use foil with the ESD foam to improve it. The idea is to have all the IC leads at the same electrical potential.

    Here is something I wrote for the AAC book a while back...

    ElectroStatic Discharge
     
  6. marshallf3

    Well-Known Member

    Jul 26, 2010
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  7. BMorse

    Senior Member

    Sep 26, 2009
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    A typical multimeter is all I use to test anti static packaging foam for resistance.....

    B. Morse
     
  8. Wendy

    Moderator

    Mar 24, 2008
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    Something that happened at one of my old jobs is we got a bunch (a really large amount) of pink conductive bags. Problem was, they were counterfeit! This kind of stuff is an ongoing problem in the electronics industry.
     
  9. Nik

    Well-Known Member

    May 20, 2006
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    I've a similar problem in that I want to store several dozen 'identical' 8-DIPs anti-static and in sequence so I can run multiple tests on each...

    I didn't have any anti-static foam, and my usual alternative of lining trays with alumin(i)um cooking foil risked chips hopping loose. I nearly soldered a bag full of DIP sockets to a slab of strip-board but, after much head-scratching, I found some 32-way SIL plug headers intended for daughter-board connections.

    Zig-zag soldering some bell-wire between the standing pins shorted them. Plugged into a cheap proto-board, each bus-bar shorts enough rows for 8 chips. I've also seen these headers in 20-way, which would do four chips at a time.

    The important thing is that your plug strips have a low insertion force. Mine had slightly different diameters pins on 'board' and 'plug' sides. One 'glided' into the protoboard, the other would have needed forcing...

    Now all I've got to do is manually collect enough data...
     
  10. DigitalReaper

    Thread Starter Member

    Aug 7, 2010
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    Thanks for the replies everyone, a lot of useful information in here :)

    Assuming that the foam I have is fake stuff, would covering it with foil make it suitable for storing ICs? I was thinking of putting foil on both sides of the thin pink sheets (approx 3/16" thick), and possibly doubling that up if the leads come through.
     
  11. marshallf3

    Well-Known Member

    Jul 26, 2010
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    People have used foil for years, just don't use it on styrofoam which is a very static creating material. (think of packing peanuts)
     
  12. Potato Pudding

    Well-Known Member

    Jun 11, 2010
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    Strongly agreed.


    If you work on a grounded metal bench or have a conductive mat on your work surface you are 90% ESD safe as far as I can tell. And that is pretty good since you will never be 100% ESD safe - Static is just tricky sneaky stuff sometimes.

    I avoid working with high value chips and components and since I seem to have managed to avoid ESD problems I don't worry as much about the low value components I normally try and use. If I do have a $10+ IC that I have to work with, I will try and remember to keep a static strap on my arm and all the other measures.

    Regarding the foam, I never heard of counterfeiting but I suspected that some of it would be bogus, since I have priced the differences between for example a roll of antistatic bubblewrap and normal plastic bubble wrap.

    I will try to remember to verify antistatic packaging before I use it for high value products.
     
  13. Wendy

    Moderator

    Mar 24, 2008
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    I've had 2N2222A blow due to ESD damage, so don't get too cavalier about it.
     
  14. retched

    AAC Fanatic!

    Dec 5, 2009
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    Never use a IC to scratch your head or brush your hair.

    I know it seems like a good idea..just dont do it.

    ;)
     
  15. radiohead

    Active Member

    May 28, 2009
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    I've used standard styrofoam coated with aluminum foil before. I've never had a problem...yet. Why not keep your chips in the antistatic tube they came in? Just have a few in your parts box for experimentation until you need one for permanent use? Store the rest somewhere where they won't be exposed to too much humidity, or excessive heat.
     
  16. jpanhalt

    AAC Fanatic!

    Jan 18, 2008
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    Yep. Nothing like being almost pregnant. :D Now, "90% safe" could mean you screw up only 1 out of every 10 chips, or it could mean you mess up at least one pin on every chip.

    After you solder all those chip into place, it can be really hard to find the bad one.

    John
     
  17. Wendy

    Moderator

    Mar 24, 2008
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    One of the reasons I posted the ESD article is it goes into depth on the subject. Especially do it yourself ESD safe tables.
     
  18. marshallf3

    Well-Known Member

    Jul 26, 2010
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    I'd say a lot depends on your level of experience and work area as well.

    I forgot where I bought it but it isn't hard to find anti-static spray concentrate. You simply dilute it with water in a spray bottle and lightly mist your work area and surrounding environment.

    I tend to avoid working in carpeted areas, vinyl or similar tile flooring can be a problem as well. On the other hand concrete, since it naturally maintains a certain amount of moisture, is probably best.

    Another mistake some make is thinking that a cold water pipe or the ground of an electrical outlet (or conduit) is a solid earth ground. It rarely is unless it's a cold water pipe very near the point of entry from a point that's buried in the ground. I can't say that I've actually zapped a chip when working on a concrete floor and religiously following the habit of touching a hand to ground, to the chassis or common ground of what I'm working on and everything inbetween.

    Also be aware that anything loose on your bench can also become charged such as a screwdriver with a plastic handle.
     
  19. marshallf3

    Well-Known Member

    Jul 26, 2010
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    The first time perhaps, but over time you end up with a lot of holes. The link I posted to the place that sells good foam is a good choice or do as I once did. There are several manufacturing firms around here that just throw the stuff out. A few phone calls found me a place that gets assemblies which come with a sheet of foam on the back side of the board as they come packed. I kindly explained that I'm an experimenter and asked if they would save some for me. Came home with a box so full of it half went crumbly from age before I tossed it.
     
  20. nsaspook

    AAC Fanatic!

    Aug 27, 2009
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    We used foam but like yours did most of it gets old and crumbly after a while. We now use ESD bins, tubes and bags for most common parts.

    http://www.newark.com/pdfs/datasheets/spc/84n1456.pdf

    SPC 300 series.
    http://www.newark.com/jsp/content/printCatalog.jsp?display=single&cat=c127&page=2124


     
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