FreeLists / si-list / [SI-LIST] Re: ESD strips on board edge

[Doug Smith <doug@xxxxxxxxxx>]

Hi Koh,

You could title this subject "The Board of the Rings."

If you mean ESD guard rings, this topic is worth several pages of 
typing, actually a whole chapter in a book. These often make things 
worse under a number of conditions. Keep in mind the voltage drop 
along one of these paths during ESD events can be hundreds of volts or 
more from Ldi/dt drop and this gets into other paths my Mdi/dt.

Never connect an ESD guard ring through the board connector to ground. 
It just deposits the ESD energy right into your backplane (whether you 
think you connected it to "chassis" ground or not. A hundred volts 
induce in series with nearby connector pins would not surprise me.

Beware of static charge building up on this path when the board is not 
in a system by charge induction by nearby charges. This can create a 
destructive ESD event where there would have been none except for the 
presence of the ESD ring unless there is a conducting path between the 
board and the ring.

I have barely touched the surface of this topic. If you want to call 
me on the phone, I can eliminate lots of typing.

Doug

Thoon, Koh Yew wrote:

> =20
> Hi folks,=20
> 
> I wonder if there's any good documents on implemenation of ESD strips
> for Board edge.
> 
> Thanks
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