It has been my experience that the ESD policy needs to be set by
measurements, data, and more measurements, not logic. Otherwise, ESD
programs can get very expensive to implement.
One of my many hats as a process engineer has been ESD Program Manager, and
while I agree that the aforementioned rationales seem totally logical, I'd
like to know if Mike and Howard have actually measured the voltage
potentials involved.?
I've studied this particular situation very extensively and every time find
that there is no difference between standing, sitting, or even sitting with
their feet in the air.
My conclusion has always been that the large hull effect of the dissipative
floor does not allow for the potentials to accumulate on the operators
above it.
If anyone does have data contrary to this, I'd appreciate a chance to
discuss this with them.
Phil Bavaro
"ESD Program Manager"
____
At 08:47 AM 11/5/99 -0500, Cyker, Howard A (Howie) wrote:
>The rationale for using a wrist strap when seated is to provide a consistent
>and constant level of grounding. Grounding through conductive chairs would
>rely on grounding through the clothing, which is unpredictable and
>unreliable. Grounding through conductive shoes, of course, requires
>constant contact with the floor, which cannot be guaranteed while sitting.
>
>> Howard A. Cyker
>> Lucent Technologies
>> Email [log in to unmask]
>> Phone 978-960-2964
>>
>>
>>
>> ----------
>> From: d. terstegge[SMTP:[log in to unmask]]
>> Reply To: TechNet E-Mail Forum.;d. terstegge
>> Sent: Friday, November 05, 1999 4:27 AM
>> To: [log in to unmask]
>> Subject: [TN] Wrist wraps for seated operators
>>
>> Hello Technet,
>>
>> We've recently received some complaints from a customer who is not happy
>> with the fact that our operators don't wear wrist wraps during seated
>> operations like handsoldering and inspection. Our factory relies on
>> grounding through the (conductive) chairs, ESD-shoes, conductive floor and
>> ESD-workbenches, but the chairs are tested only once per year, which is
>> obviously less frequent then one would test wrist wraps.
>> Is the customers concern justified, and should we introduce wrist wraps ?
>>
>> Daan Terstegge
>> Unclassified
>>
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