Perforated Holes in Sheetmetal - Which is best for EMI? 2

[oharag]

We are designing a electromechanical device, and are considering how to isolate EMI/EMF in our design. I realize it's best to use a conductive material to shield or enclose any emitting source. Also, smaller perforations in the enclosure should be used to account for cooling issues if needed (small enough so that any transmitting wave can not escape to the outside world). My question is doesn't it really matter what these perforations look like. There are honeycomb like perforations on the back of my PC for the exhaust fan. The honeycomb is staggered to achieve excellent airflow for the fan. In other places where a fan is not used and I only need natural flow of air I want to use plain circles. My boss says to go with the honeycomb, because it supposedly provides better EMI/EMF shielding. I say the honeycomb is only used in fan cooling because you pack them tighter together for cooling. Any thoughts.

oharag

 

[Tunalover]

There's a publication called "Designer's, Specifier's, and Buyer's Handbook for Perforated Metals" put out by the Industrial Perforators Association (IPA) that has attenuation tables for various perforation patterns, thicknesses, and materials. I got mine from McKey Perforating Co., Inc. 800.345.7373 but that was something like 10 years ago! It contains reams of other useful information about sheetmetal and perforations too!



Tunalover

 

[Heckler]

Thanks tunalover this handbook is a great resource.

here is the current handbook link

http://www.iperf.org/perfhand.htm

Heckler