his article assumes the reader already has a basic understanding of how electromagnetic compatibility (EMC) shielding works. If you would like a refresher on EMC shielding, please see references 1 and 2, which describe how EMC shielding works in basic terms.
If you’re an electrical engineer and consider proper EMC shielding a mechanical only issue, please reconsider your position and keep reading.
This article covers some of the most common reasons why our first attempts at proper shielding, as described in the situation above, were all in vain. The problem is usually that the EMC shielding design incorporated the weaknesses described below from initial inception and the SE was already defeated by design.
Another reason why the SE for the example situation may have not been good enough is because slots in the shield were rendered useless by the application of non-conductive paint or covers, or possibly by poor-fitting panels or doors. These effects may have gone unnoticed as they are sometimes harder to locate than the more visible issue of the slot being too long. From now on, all new shielding and enclosure designs will be checked to ensure these issues are avoided.
The shielding may have also been compromised due to other penetrations through shielding necessary for proper product functionality. These could include intended conductors, such as signal/power lines or unterminated cable shields. In these instances, we should have added proper EMI filtering of these lines that would have helped reduce their impact on defeating the shielding.
For more information on this important subject, please see the following:
- In Compliance Magazine. (2018, August). “What Every Electronics Engineer Needs to Know About: Shielding.” Retrieved from https://incompliancemag.com/article/what-every-electronics-engineer-needs-to-know-about-shielding
- Gerke, D., Kimmel B., “The Designer’s Guide to Electromagnetic Compatibility.” EDN. 2005.