Where do RFI / EMI Shielding Coatings and Paints fit in?

Plastic Enclosure that can be shielded by conductive Shielding Coatings.

Commonly, to reduce costs, manufactures assemble their devices within plastic enclosures.

Plastic is non-conductive, and therefore does nothing to prevent the transmission of EMI/RFI. If the enclosed device is not perfected designed with circuit level EMC, the enclosure must be shielded. The most straightforward way to shield an enclosure is to make the inner surface of the enclosure conductive.

There are multiple ways to achieve this, but a simple cost effective solution, is to spray or brush the inner surface with a conductive paint. These conductive paints are typically acrylic based, and pigmented with non-oxidizing metallic flakes, such as nickel, silver-coated copper, or silver. Graphite is sometimes used in non-critical low energy systems where cost is a concern. Copper is sometimes used, however it is not good in corrosive environments. Nickel tends to be most commonly used in situations where the peak EMI is less than 30Mhz, and silver coated copper or silver is used in higher frequency applications. Silver is very expensive, however. Epoxy bases are sometimes used in aerospace and military applications, and other applications where the coating will be impacted and durability is a concern.

Normally durability and corrosion resistance are not large concerns, because shielding is usually put on the inside of a water tight container. There are many niche applications for shielding, however, so all of these coatings come into play somewhere.

Companies like MG Chemicals offer a range of conductive paint solutions that can provide EMI/RFI solutions for plastic enclosures.

If you would like to know more about EMI / RFI Coatings or other products and services offered and supported by SCH Technologies, please do not hesitate to contact us on +44 1226 249019, email us at sales@schservices.com or click RFI / EMI Shielding Coating Services or click Contact Us to send us your requests.


About Dr Lee Hitchens

Dr Hitchens has been working in the electronics industry and the area of conformal coatings for over 25 years in various areas including sales and technical support. He has also been training people for almost the same amount of time in all areas of conformal coating whether that is materials & equipment selection, process development or troubleshooting to help them solve their particular problem. Recently, he decided that the industry needed a specific place where all of the useful knowledge on conformal coatings could be collated for users to find easily and use in their own production process. So, Nexus was born and he began the Nexus eBook project.

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