EMI/RFI shielding protects electronic circuits and electrical equipment against electromagnetic interference (EMI) and radio frequency interference (RFI). These industrial rubber products use an elastomer such as silicone or fluorosilicone as the base sealing material. This elastomer is filled with silver or silver-coated particles that provide electrical conductivity and EMI/RFI shielding.
EMI elastomers provide environmental sealing, electrical conductivity, and EMI/RFI shielding. Because nickel-graphite silicones are available in 30, 40, and 45 durometer (Shore A), they’re soft enough for enclosure gaskets. Other, higher-durometer shielding elastomers that use fluorosilicone as the base elastomer can resist fuels and chemicals. These fluorosilicone compounds come in 50, 60, and 80 durometers (Shore A) for applications that require EMI gaskets made of harder materials.
Unlike older EMI elastomers, newer materials contain enough metal filler to ensure effective shielding and electrical conductivity. During EMI gasket cutting, these particle-filled silicones won’t stretch or become deformed. Connector holes align properly, and the elastomer’s structural properties support greater tear resistance, which is an important consideration for thinner wall gaskets.
Higher-durometer, nickel-graphite silicones are available, but some EMI gasket applications require reinforcement for added strength. That’s why EMI materials include products such as 65-durometer elastomer that’s reinforced with an internal nickel-coated mesh. Lower-durometer, nickel-graphite silicones can also be reinforced with an inner layer of conductive fabric for added conductivity and material strength, which helps to prevent brittleness and tearing during EMI gasket fabrication.
EMI Gasket Applications
EMI shielding and RFI shielding are used in mobile equipment electronics, LED lighting, consumer electronics, and wireless communications. In these and other applications, electromagnetic emissions can interrupt, obstruct, degrade, or limit the performance of circuits in the same system or a nearby system. Additional applications include medical devices and military land systems.