For question #4., EOS/ESD 20.20 has a supplementary document that spells
out the requirements for testing the smocks and laundering. You could
simply flow that document down in your p.o. with the company you lease
your smocks from.
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Guy Ramsey
Sent: Monday, September 08, 2008 9:34 AM
To: [log in to unmask]
Subject: Re: [TN] Questions on ESD control
The conductive epoxy floor finish that I have used only required
cleaning and monitoring.
I have seen anti-static materials clear and blue. Conductive totes and
trays only black.
Paper does generate and hold a charge. We kept it on the floor in
anti-static sleeves so as you turned the pages it did not (generate a
charge).
ESD TR20.20 does specify safe distance from sensitive work in a ESD safe
workstation.
This applies to paper, packaging, monitors anything that can hold a
charge.
As I recall it was 1 inch per kV potential. So, a sheet of paper that
could have a 10-15kV potential would need to be 10-15 inches from the
work. A computer monitor which might have 25kV potential on the glass
screen 2 feet away. Maybe it wasn't TR20.20 but the Mil Handbook . . .
263?
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Blair Hogg
Sent: Monday, September 08, 2008 7:51 AM
To: [log in to unmask]
Subject: Re: [TN] Questions on ESD control
Hi Rudolph,
See my responses within.
On Mon, 8 Sep 2008 04:22:58 +0000, Rudolph yu <[log in to unmask]>
wrote:
>Hi Technet members:
>
>I am reviewing the current ESD practices at a OEM /EMS company
which I have just joined couple months ago, and would like to seek for
your expertise.
>
>1. The company uses epoxy pouring material +coating for the ESD
floor. According to the ESD hand book TR20.20, this type of ESD floor
"DOES NOT" require maintenance. How true is this statement? If a
customer ever challenge me on this, can I just direct him to the ESD
handbook? (of course the point to point, point to ground resistances has
to be within the acceptable range)
>
Do you have any documentation on the flooring? Does it have dissipative
properties? Can you show your customer a spec sheet from the
manufacturer that it doesn't require maintenance (other then periodic
cleaning)?
>
>2. We use plastic tray to move assemblies between workstations with
the whole facility which is considered as EPA. ( I am assuming the tray
material is dissipative material) Is there anything we need to be
aware
of? What if my assumption is wrong and the material turns out to be
insulative? What can we we address this then?
>
Are the trays black plastic? I haven't seen any plastic other than black
that has dissipative properties. Do you know from where they were
pruchased and have any information on them?
>3. We put the BOM, assemblies, drawing on the tray along with the
assemblies within the EPA area( and I dont think they are ESD paper).
Is this acceptable practice as far as ESD concerns? Do we "have to"
cover all the documents in dissipative sleeve? Even if we use the
sleeve, the inspector will need to take the BOM and assembly drawing
out during the actual inspection ( for the highlight and crossout), what
can we do to prevent static from being generated? Will it be ok as long
as the inspector is grounded by wrist strap and heel strap?
>
Paper is not generally considered to be a static generator, but that
depends on the humidity level in your facility. If its is typically dry
(<20%RH) you might have a problem. If it is typically 30-50% RH, you
are probably OK. General rule of thumb is to keep all non-dissipative
materials separated from ESD sensitive components as much as
possible.
You can also use ionizers at ESD workstations to dissipate static
charges on the papaerwork.
>4. We are renting the ESD garment from an outside company. What
kind of spec should they follow for the periodically inspection and
laundry services when we return the garment to them?
>
Again I would defer to the garment manufacturer's guidelines. See if
they have a copy of them.
>Thanks for the help.
>
>Rudolph
>
Hope this helps.
Blair
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