[SI-LIST] : Electromagnetic shielding

About this list Date view Thread view Subject view Author view

From: [email protected]
Date: Wed Nov 15 2000 - 04:17:12 PST


I haven't seen a recent discussion of electromagnetic sheilding on this
list so I have
the following request.

I'm working on a design involving an ASIC with an 80 MHz clock and SDRAM.
concern is electromagnetic radiation. Because of constraints, I can't use
spectrum techniques and the product won't go into a metal enclosure. I'd
like to
enclose a portion of the circuitry (the ASIC and SDRAM) under a small metal
mounted to the circuit board. I'm doing this in anticipation of radiation
I don't have earth ground directly available so I suppose the cover will be
connected to digital ground.

Does anyone have (or know of any ) guidelines for using a cover like this
to restrict
electromagnetic radiation? I need answers like 1. how close to the board
does the
cover need to be, 2. how many ground contacts are needed around the
of the cover and 3. what special considerations are there for the PCB
directly under
the edges of the cover?

I've looked in a few book references but don't see a treatment of this

Any help is greatly appreciated.


Tom Tokar
Rockwell Automation

**** To unsubscribe from si-list or si-list-digest: send e-mail to
[email protected] In the BODY of message put: UNSUBSCRIBE
si-list or UNSUBSCRIBE si-list-digest, for more help, put HELP.
si-list archives are accessible at http://www.qsl.net/wb6tpu

About this list Date view Thread view Subject view Author view

This archive was generated by hypermail 2b29 : Tue May 08 2001 - 14:30:08 PDT