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ESD Smocks and chairs

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ESD Smocks and chairs | 5 June, 2007

We are looking at ESD chairs in our EPROM room. Currently we are using smocks with wrist straps, this was set up before me. Is there any special or different things that needs to be done to the smocks to make them work with an ESD chair?

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ESD Smocks and chairs | 5 June, 2007

LarryP, ESD smocks in combination with a wrist strap provide a path to ground for any charge potential. An operator wearing a smock while grounded will provide a path to ground for the chair. With an ESD chair you can have antistatic or static dissipative varieties. Neither one will cause any problems for you, especially if the floor is treated with an ESD finish.

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ESD Smocks and chairs | 6 June, 2007

Thanks for the help but I do have another question.

First I guess that just the touching of the smock to the skin is anough to give the charge on the person a path to the smock. OK I can accept that if button up at the breast and sleeves. Now I know how to test ESD chairs and I know how to test smocks, do I test the person to ground through the snock and chair? If so, should I see 10x6 to 10x8 ohms or a different readings when testing?

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ESD Smocks and chairs | 19 June, 2007

The first thing that I would do is contact the smock manufacturer and ask them for advice on testing the smocks.

ESD FROM A TO Z 2nd ed. (Kolyer) states that:

smocks should have a resistivity of less than 10^12/sq and must not shed steel fibers.

conductive chairs should have a surface resistivity of less than 10^5 ohms/square and less than 1 megohm resistance from upholstery to surface when the chair is on a conductive surface.

I would check the ol' S20.20 2007 and J-STD-001 for more information. The ESDA S20.20 standard seems to be best when coupled with their purchasable documents. The ESDA ( also lists references like the A to Z book to facilitate a deeper understanding of ESD and ESD control. (they better send me my check! ---j/k)

If you don't have to test them to adhere to industry or internal standards, then DON'T. If there's one thing I can't stand its an ostentatious quality program.


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