>-----Original Message-----
>From: Chris Maxwell [mailto:chris.maxw...@gnnettest.com]
>Sent: Monday, April 23, 2001 4:45 AM
>To: 'Dan Kinney (A)'; Douglas C. Smith; Terry Meck
>Cc: emc-p...@ieee.org
>Subject: RE: ESD generators max Contact discharge level
>
>
>
>Hi Dan,
>
>Air discharges are made anywhere on the product where an
>insulator covers
>possibly sensitive features.
>
>Membrane keypads are a great example. The keypads contain traces and
>circuitry that may be sensitive to ESD. However, since the
>outermost layer
>is an insulator, making a contact discharge would not be a
>real world test.
>I believe that it may also damage the contact discharge relay
>in certain ESD
>generators. I can explain that in more detail if you would
>like. In my
>experience, membrane keypads are always tested with air discharge.
>
SNIP
>
>Chris Maxwell
>Design Engineer
>NetTest
>6 Rhoads Drive, Building 4
>Utica,NY 13502
>email: chris.maxw...@gnnettest.com
>phone: 315-266-5128
>fax: 315-797-8024
>
Chris:
I don't understand why a membrane switchpad would not be tested for contact
discharge. It think that this is the absolutely most likely place where a
finger, attached to a charged human body, might be applied to the EUT. It
seems to me that you would want to be testing the dielectric strength of the
insulation over the keypad conductive traces.
The issue of whether a triggering of the testing gun, without a completed
discharge current, would damage the gun, isn't relevant to the need for the
test. Dumping 15 or 20 kV to a probe tip, while not exactly trivial, still
shouldn't be critically sensitive to load conditions.
Regards,
Ed
Ed Price
ed.pr...@cubic.com
Electromagnetic Compatibility Lab
Cubic Defense Systems
San Diego, CA USA
858-505-2780 (Voice)
858-505-1583 (Fax)
Military & Avionics EMC Services Is Our Specialty
Shake-Bake-Shock - Metrology - Reliability Analysis
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