June 26, 2022
EMI Shielded Vent Panel
EMI Shielded Vent Panel



EMI shielding in electronic devices and equipment is the use of manufacturing techniques and materials to shield signals from disturbance by external electromagnetic signals and to prevent generated signals from interfering with surrounding components.

Electromagnetic Interference (EMI) can disrupt electronic devices, equipment and systems used in critical applications. Examples include medical, military, and aerospace electronics; mass transit systems; industrial touch screens; and vehicle navigation and control systems – to name a few. The causes of electromagnetic interference are many and include both man-made and natural sources. The results can range from temporary disruptions and data loss to system failure and even loss of life.

For engineers, it is important to recognize how electromagnetic energy (EME) in the application environment can cause interference. Without this basic knowledge of EMI, you can design gaskets that lack adequate shielding against electromagnetic fields in the radio frequency (RF) spectrum, the part of the electromagnetic spectrum with frequencies from 3 kHz to 300 GHz. RF waves are the basis of radio technology, but they can also transmit signals that interfere with wireless communications.

In general, sources of EMI can be divided into two broad categories: ambient EMI and power quality issues. Rail and transit systems, medical equipment and military applications also face their own specific challenges. Increasingly, intentional electromagnetic interference (IEMI) also poses a threat to non-military assets such as the power grid and other types of critical infrastructure. An EMI shielding gasket is a mechanical device that helps protect electronics from electromagnetic interference. Traditionally, EMI shielding has been made from sheet metal and formed into shapes that fit electronic enclosures or enclosures. Aluminum, copper and steel are strong and rigid, but thin sheets can deform under the pressures needed to seal. Once metallic EMI shields are deformed, they tend to retain that shape and can allow leakage to and from electronic circuits.

Today, EMI shielding materials include flexible metal shields, metal wires, and metal foams. Coatings based on metallic inks are also applied to the inside of electronics enclosures to provide an EMI shielding solution. Each of these shielding methods has its benefit , but particle-filled silicone combines the electrical properties of metal with the material properties of silicone rubber. For product designers who face various sealing and insulation challenges, silicone filled with metal or particles covered with metal is an excellent choice. For example, the EMI gaskets used in some rugged touchscreens are made of particle-filled silicones that attenuate EMI emissions, provide electrical conductivity, and provide environmental sealing in conditions ranging from desert heat to arctic cold. These EMI shielding gaskets should protect the device from mechanical shock and be flexible enough to avoid interfering with the touch screen function. Material costs and ease of fabrication are also important to seal designers in many different industries.