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May 2005

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Subject:
From:
Mike Sewell <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, [log in to unmask]
Date:
Sat, 7 May 2005 06:29:35 -0500
Content-Type:
text/plain
Parts/Attachments:
text/plain (184 lines)
ESD sensitive devices can have a charge induced on them when moving near a
charged object if they are not grounded or in a static shielding
bag/faraday cage.  The charge is dangerous in that the part now discharges
when contacted by a grounded object/person - depending on the rate of
discharge (ex. dissipative workbench vs. conductive tool or surface) damage
may occur.

Mike


|---------+------------------------------>
|         |           "Blair K. Hogg"    |
|         |           <blair.k.hogg@GAI-T|
|         |           RONICS.COM>        |
|         |           Sent by: TechNet   |
|         |           <[log in to unmask]>  |
|         |                              |
|         |                              |
|         |           05/06/2005 02:46 PM|
|         |           Please respond to  |
|         |           TechNet E-Mail     |
|         |           Forum; Please      |
|         |           respond to "Blair  |
|         |           K. Hogg"           |
|         |                              |
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  |       To:       [log in to unmask]                                                                              |
  |       cc:                                                                                                    |
  |       Subject:  Re: [TN] FW: Static and break over voltage spacing standards?                                |
  >--------------------------------------------------------------------------------------------------------------|




I was under the impression that sensitive devices could be harmed by a
close electric charge, that it didn't have to make a jump, due to the
effects of the electric field. Could be I was mistaken.

Can the plastic panels be coated with a topical antistatic compound?

Blair

>>> [log in to unmask] 05/06/05 03:23PM >>>
Hey, where are the ESD gurus?  Can't static electricity go to 30K or
40KV?  That is going to need a much bigger gap.  How about a section of
copper window screen that is grounded?

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Dehoyos, Ramon
Sent: Friday, May 06, 2005 3:16 PM
To: [log in to unmask]
Subject: Re: [TN] FW: Static and break over voltage spacing standards?


          From a previous life I was taught that a see level a 10KV will
jump 1 inch. The higher the elevation the longer the distance that will
arc to due to less air or less impediment.  But I have seen articles
published that say that is less than 1 inch for 10 KV.
          Regards,
          Ramon

-----Original Message-----
From: TechNet [mailto:[log in to unmask]]On Behalf Of Brooks,Bill
Sent: Friday, May 06, 2005 11:07 AM
To: [log in to unmask]
Subject: [TN] FW: Static and break over voltage spacing standards?


I hope that someone on the forum may have a comment or two about this
subject... and can help John.

- Bill

-----Original Message-----
From: John Smith [mailto:[log in to unmask]]
Sent: Thursday, May 05, 2005 7:21 AM
To: 'Bill Brooks'
Subject: RE: Web site question

Thank you for your response Bill, I am trying find out at what voltage
and
at what distance I need to be concerned about a static discharge from a
plastic surface. I have a silicon wafer processing tool and there is
concern
about static discharge from the exterior plastic panels. I want to be
able
to determine, the voltage vs.. distance safe point, i.e. (at 500v of
charge
an arc will not jump at a greater distance than .5") I understand that
the
type of material, the humidity and other factors make a difference, but
there must be some test data some where that points to some
generalities.

Thanks again for your time bill

John

-----Original Message-----
From: Bill Brooks [mailto:[log in to unmask]]
Sent: Wednesday, May 04, 2005 11:03 PM
To: 'John Smith'
Subject: RE: Web site question

http://sprott.physics.wisc.edu/demobook/chapter4.htm

see table 4.2

The issue with predicting electrical arcing is in defining the
environmental
conditions that contribute to the 'break over' voltage. The presence of
dry
ionizing air, or ionic contamination on a surface can greatly increase
the
distance at which break over will occur. Once the arc is established, it
ionizes an electrical path which is much lower in resistance that the
initial break over voltage required to jump across the electrodes and
the
two points of potential can be moved much farther apart and they will
still
conduct...
What are you trying to do?

Bill Brooks


-----Original Message-----
From: John Smith [mailto:[log in to unmask]]
Sent: Wednesday, May 04, 2005 2:09 PM
To: [log in to unmask]
Subject: Web site question

Is there a guideline that references how far a static charge will jump?
i.e. a 500v charge could be expected to jump or ark how far?



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