Per Table 3 of ANSI/ESD S20.20-2007, ESD Flooring is to be < 1 x 10E9 ohms.
Bare concrete would likely pass some of the time. Concrete is hygroscopic,
readily absorbs moisture from the air. It would be the contaminated water,
not the concrete, providing the path to ground.
So, one likely could collect data to show that at a level of relative
humidity or higher, the RTG < 1 x 10E9 ohms could reliably be met. Then,
stop work when the relative humidity hits a certain level.
Covering the bare concrete with dissipative floor finish, conductive paint,
or using grounded ESD mats would be the recommended solution.
Gene Felder
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Whittaker, Dewey (EHCOE)
Sent: 2009-01-23 7:50 AM
To: [log in to unmask]
Subject: Re: [TN] ESD Flooring - bare concrete
Without knowing the level of sensitivity of the equipment/components and
the ability to control relative humidity, I'll have to contribute to the
Doug Pauls Mt. Dew Memorial Fund. I hear he's keeping them in the
freezer for awhile, so this really is turning into a slush fund.
Dewey
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Steven Creswick
Sent: Friday, January 23, 2009 8:39 AM
To: [log in to unmask]
Subject: Re: [TN] ESD Flooring - bare concrete
Dewey,
I think I understand your response, but the question still remains - is
a
bare [untreated with anything] concrete floor [without mats to trip
over]
able to minimize charge build-up?
His parts are crude, and pretty macroscopic by our standards. His
objective
is crude, and he needs it low cost, but reasonably safe for people and
product. I know if one were to do it the way we normally would, I would
coat the floor, or put down ESD tiles and call it quits. He is on less
than
a shoestring budget, trying to make do as best as he can.
The ESD people want to sell him mats and treatments that he can not
afford.
Hence the question
Steve
-----Original Message-----
From: Whittaker, Dewey (EHCOE) [mailto:[log in to unmask]]
Sent: Friday, January 23, 2009 10:26 AM
To: TechNet E-Mail Forum; Steven Creswick
Subject: RE: [TN] ESD Flooring - bare concrete
Obvious is a treated concrete floor with an ESD safe coating. The
downside is maintenance and cleaning.
Large ESD mats may be better with dedicated ESD safe work areas.
Dewey
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Steven Creswick
Sent: Friday, January 23, 2009 8:13 AM
To: [log in to unmask]
Subject: Re: [TN] ESD Flooring - bare concrete
Brian - Joyce,
This is HEAVY equipment [ie - dirty, filthy, grimy]. I have very little
concern about dirt and dust - just ESD suitability.
Any comments on suitability of the bare concrete floor to mitigate
charge
build-up and/or transfer?
Steve
-----Original Message-----
From: Brian Ellis [mailto:[log in to unmask]]
Sent: Friday, January 23, 2009 6:39 AM
To: TechNet E-Mail Forum; Steven Creswick
Subject: Re: [TN] ESD Flooring - bare concrete
Dust?
Brian
Steven Creswick wrote:
> Techies,
>
>
>
> My first Friday, pseudo-technical question - I have an acquaintance
that
is
> repairing pretty crude PWB assemblies used in the trucking industry
and
> needs to re-locate to gain more room. He certainly does not require
> clean-room conditions.
>
>
>
> My thought was that a bare concrete floor - free of oils and greases,
epoxy
> coatings, etc. - would work out ok for flooring. If he had carts, he
could
> attach small brass chains, etc.
>
>
>
> Was also thinking that the floor would give up moisture in the Winter
and
> absorb it during the Summer and thereby help buffer humidity swings.
>
>
>
> He still would require ESD work-stations.
>
>
>
> What say the more ESD gurus?
>
>
> Steve
>
>
>
>
>
>
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