What Is Electromagnetic Interference (EMI) and How Are We Affected By It?

Electromagnetic interference (EMI) is defined as electromagnetic wavelengths or signals that interfere with an electronic device’s performance. Any electronic device or circuit can emit these unwanted signals and/or be susceptible to them. If not shielded properly, EMI can have a severe adverse effect on a device, to the point of ceasing functionality. EMI may also be referred to as Radio Frequency Interference (RFI). The Parker Chomerics Shielding Products sold by Marketing East can eliminate or reduce this EMI.

What is EMI Shielding?

EMI Shielding (Electromagnetic Interference Shielding) is the use of electrically conductive materials to either protect electronic systems from outside EMI wavelengths or prevent EMI wavelengths from escaping. The perfect EMI shield would be a six-sided welded (seamless) metal (conductive) box or “Faraday Cage.” The key to EMI Shielding is simulating a Faraday Cage. Electronic system designers need to be mindful of any non-conductive surfaces, seams, gaps or openings which could allow EMI wavelengths to pass. If the EMI wavelengths pass, then the signals can interfere with the device’s performance and additional EMI shielding is necessary.

Marketing East provides a variety of Parker Chomerics EMI shielding products that act as barriers or seals against these unwanted EMI signals. These products make non-conductive surfaces electrically conductive, seal gaps and can create what is known as a Faraday Shield. A Faraday Shield is made by placing a continuous coating of conductive material (shielding material) on the non-conductive surface. The Parker Chomerics EMI shielding product categories include: electrically conductive coatings, electrically conductive elastomer gaskets, wire mesh gaskets, sealants, epoxies and adhesives. These shielding products provide excellent levels of EMI shielding effectiveness over a wide frequency range.

EMI Shielding and Plastic Enclosures

Plastic and composite substrates are desired materials for many electronic systems due to their weight, resistance to galvanic corrosion, design flexibility and low cost.  Plastic, however, is a non-conductive material and EMI wavelengths can pass right through it affecting components, circuitry and system functionality.  This means EMI shielding is of increasing importance to system designers.

The Parker Chomerics CHO-SHIELD line of EMI coatings adhere to plastics and other composite substrates to create an electrically conductive surface or housing which can absorb electromagnetic radiation before it affects a device.  These coatings are commonly used on electronic assemblies, as well as aircraft and airframe components.  The CHO-SHIELD products have great adhesion properties and are used across a wide range of applications and substrates. Along with providing substantial shielding capability, CHO-SHIELD 2001, CHO-SHIELD 2002 and CHO-SHIELD 2003 are ideal for extreme environmental conditions as they have excellent corrosion resistant characteristics.

EMI Shielding for Covers, Doors and Openings

When designing for EMI Shielding, design engineers need to eliminate all seams and gaps that are larger than any potential interfering external electromagnetic radiation wavelength. The design should also avoid any elongated slots that EMI could escape through. Electronic device covers and doors are highly susceptible to EMI leaks, requiring EMI shielding gaskets and EMI shielding sealants.

Marketing East sells a variety of EMI shielding gaskets including the CHO-SEAL electrically conductive elastomers, wire mesh, and conductive fabric over foam gaskets.  Additionally, Marketing East stocks most of the CHO-BOND electrically conductive sealants and adhesive. Using these sealants, gap fillers and gaskets usually resolves EMI issues.