What is EMI-RFI Shielding?
EMI stands for electromagnetic interference while dealing with radio frequency; it is addressed as radio-frequency interference. Interferences can cause a disruptive disturbance with electronic devices via radiated or conducted paths. In return, these disturbances can degrade and limit the effectiveness of a circuit. There are usually two types of EMI/RFI interference – Narrowband and Broadband
EMI can adversely affect the performance of electronic components, devices, or systems and may cause malfunctions in electronic devices. EMI/RFI can cause suppression of signals that interfere with equipment operation. The goal of all engineers is to achieve Electromagnetic Compatibility in their designs.
EMI-RFI shielding can be applied in the form of spray paints or coatings to electronic as an effective solution. The spray is often acrylic-based and helps in reducing the effects of interference. EMI-RFI shielding can be brushed on the exterior of the enclosure to eliminate or reduce interference.
EMI-RFI shielding consists of highly pure elements such as nickel, silver, and copper which help to reduce or eliminate EMI/RFI interference.
Who requires EMI-RFI shielding?
EMI-RFI Shielding is important in many industries and some industries require it more than others.
E.g. in the medical industry EMI-RFI shielding plays a critical role as medical equipment can malfunction due to improper shielding and can cause negatively impact the well-being of patients. Application-specific sources include- Electrical and electronic equipment in surgical units, Life support devices such as ventilators and infusion pumps, Life support devices such as ventilators and infusion pumps, etc
Mass transit systems and Railroad may experience EMI because of some application factors such as- High voltage contact switch, rail shoes, Emissions from train control and propulsion systems, etc.
Military assets and critical infrastructure faces threats such as High altitude nuclear electromagnetic pulse, High power microwave weapons, E-bomb, EMP cannons, etc.
EMI-RFI can also interfere with cell phones and communications ad cause devastating consequences
Engineers need to examine EMI/RFI risks to include appropriate protection into their designs. Some applications significant protection against EMI-RFI, it is important to choose high-quality reliable protection
EMI Shielding Gaskets and factors to be considered while choosing it –
EMI Shielding Gaskets refers to the mechanical devices which help to protect electronics from EMI. Electromagnetic interference shielding includes flexible metal screen, metal foams, and metal wires, Coatings is applied to the interior of applications or electronic to provide EMI shielding.
EMI Shielding Gaskets comes in variety based upon geometry and materials. There are four important categories of shielding gaskets –
- Beryllium copper
- Knitted wire mesh
- Conductive particle-filled elastomers
- Conductive fabric-over-foam
Depending on the application, each one of the materials has distinct advantages and disadvantages. EMI gaskets which are used in ruggedized touch screens are made up of particle filled silicone which provide electrical conductivity and ensure environmental sealing
The most important factors to be considered while choosing a gasket are
- RF impedance,
- Shielding effectiveness
- Material compatibility
- Compression force
- Compression range and set
- Corrosion control
- Environmental sealing
Some other comprehensive factors are – Operating frequency, Materials compatibility, Load/forces, Cost, Attenuation performance, Nuclear, biological, chemical (NBC), Storage environment, etc.