[SI-LIST] Re: ESD strips on board edge
- From: steve weir <weirsi@xxxxxxxxxx>
- To: Ken.Cantrell@xxxxxxxxxxxxxxxx, <CurtM@xxxxxxxxxxx>, <davidjp@xxxxxxx>, <koh-yew.thoon@xxxxxx>, "SI-List" <si-list@xxxxxxxxxxxxx>
- Date: Fri, 05 Aug 2005 09:19:44 -0700
Ken, I prefer carbon coatings, but the principle is the same.
Steve
At 07:56 AM 8/5/2005 -0600, Ken Cantrell wrote:
>Another simple thing to do (for plastic hand-held units) is metallize the
>inside, and tongue-and-groove the mating halves. This keeps a lot of the
>events from entering the enclosure in the first place.
>Ken
>
>-----Original Message-----
>From: si-list-bounce@xxxxxxxxxxxxx
>[mailto:si-list-bounce@xxxxxxxxxxxxx]On Behalf Of Curt McNamara
>Sent: Thursday, August 04, 2005 9:41 AM
>To: weirsi@xxxxxxxxxx; davidjp@xxxxxxx; koh-yew.thoon@xxxxxx; SI-List
>Subject: [SI-LIST] Re: ESD strips on board edge
>
>
>I think the first place I saw ESD strips mentioned in print was Henry
>Ott's
>_Noise Reduction Techniques in Electronic Systems_ Here are a couple of
>things
>we do:
>
>Cut the planes back from the board edge so the ESD strip is the first
>piece
>of metal that an ESD event could couple to.
>
>Put ESD strips on top and bottom and tie them together with vias
>regularly
>(1cm or so).=20
>
>Connect the ESD strip to the "RF Ground". This will be the largest piece
>of=20
>metal that energy could couple to. It may or may not be your circuit
>ground!
>If it *is* your circuit ground make this connection in a place where
>energy cannot
>travel across the plane and damage devices.
>
> Curt
>
>Curt McNamara. P.E.=20
>Senior Electrical Engineer=20
>Logic Product Development=20
>411 Washington Ave. N Suite 101=20
>Minneapolis, MN 55401=20
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>www.logicpd.com=20
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>
>
>-----Original Message-----
>From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx]
>On Behalf Of steve weir
>Sent: Thursday, August 04, 2005 10:19 AM
>To: davidjp@xxxxxxx; koh-yew.thoon@xxxxxx; SI-List
>Subject: [SI-LIST] Re: ESD strips on board edge
>
>
>Dr. Pommerenke, one additional note: It is important to maintain=20
>dielectric sufficient separation between an ESD strip and any other PCB=20
>features so that a secondary arc doesn't bypass the ferrite. Surface=20
>contamination can be a problem.
>
>Regards,
>
>
>Steve.
>
>
>At 10:01 AM 8/4/2005 -0500, Pommerenke, David wrote:
> >Koh,
> >
> >In general, those strips are placed as landing area for sparks that hit
>
> >the edge of the board. Sparks can hit the edge of the board in two-part
>
> >plastic enclosures or during handling. However, during handling other=20
> >parts can be hit to.
> >
> >If you are working with a two-piece plastic enclosure, then it might be
>
> >a good idea to have an ESD strip on the board edge. The strip should be
>
> >connected to your "ground". I suggest to avoid a direct connection, but
>
> >to use a ferrite bead (e.g., 300 Ohm at 100MHz). The bead will survive=20
> >the ESD current, but it reduces the current amplitude and increases the
>
> >rise time. The fact that it will go into saturation is not that=20
> >critical, tests have shown that it stays somewhat efficient in reducing
>
> >the current peak amplitude and increasing the rise time. A resistor=20
> >(e.g., 1000 Ohm) would be an alternative, but most resistors will be=20
> >destroyed by the ESD current.
> >
> >Dr. David Pommerenke
> >EMC laboratory
> >University Missouri Rolla
> >www.emclab.umr.edu
> >
> >
> >-----Original Message-----
> >From: si-list-bounce@xxxxxxxxxxxxx=20
> >[mailto:si-list-bounce@xxxxxxxxxxxxx]
> >On Behalf Of Thoon, Koh Yew
> >Sent: Thursday, August 04, 2005 1:13 AM
> >To: SI-List
> >Subject: [SI-LIST] ESD strips on board edge
> >
> >=3D3D20
> >Hi folks,=3D3D20
> >
> >I wonder if there's any good documents on implemenation of ESD strips=20
> >for Board edge.
> >
> >Thanks
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