What is EMI Shielding and Why is it Important?

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Have you ever experienced Wi-Fi Internet issues or heard static on a phone call? All such issues arise due to electromagnetic interference. Electromagnetic interference (EMI) is a disruption from an external source like electronic devices, equipment, and systems that are used in critical applications. EMI is a result of either man-made or natural sources. In homes, devices like microwaves, cordless telephones, sensors, and Bluetooth speakers may cause EMI. EMI is also commonly referred to as RFI, or radio frequency interference. The natural sources of EMI may include solar flares, lightning, etc. Whether due to natural or man-made sources, EMI may lead to temporary disturbances, data losses, or complete system failure.

Electromagnetic interference interrupts a device’s performance or may even cause failure by impacting an electrical circuit via induction, electrostatic coupling or even conduction. There are two general types of EMI: narrowband (caused by the likes of radios, TV stations. or mobile phones) and broadband (caused by electrical power).
What is EMI Shielding?

When designing electric devices, engineers need to control EMI to prevent incoming or outgoing emissions of these unwanted signals/waves.  Electromagnetic shielding is the practice of surrounding electronics and cables with conductive or magnetic materials to ensure the Electro Magnetic Compatibility (EMC) of devices. EMC means that a circuit has been designed to prevent EMI/RFI disruption by shielding. EM shielding is conducted for several reasons, besides to prevent electromagnetic interference (EMI) from affecting sensitive electronics. Engineers often use metallic mesh shields inside a particular device to protect one component from affecting another. This practice can also increase the security of air-gapped systems.

EMC Shielding covers PCB elements such as IC chips and active components, or connectors and cables between PCBs. The process of EMI shielding involves using a metallic screen to absorb the electromagnetic interference that is being transmitted through the air. Several techniques and materials can be used for EMC Shielding.

There are many kinds of EMI shield devices and one of the most popular is EMI shielding gasket. It consists of either metal or plastic parts that fit directly into electronic housings or compartments to help negate any interference. Another solution is EMI Coatings that uses paint mixed with conductive metals that form a shield. Coatings are very flexible because you only need to brush them onto a surface for them to work. There are also conductive silicones that can also help minimize EMI.

The material used for shielding depends on the type of electronics and frequencies involved. For example, a high conductivity, cost-effective shielding material for ultra- to super-high radio waves is Aluminium. It is also feasible to use copper or steel as these are also highly conductive, capable of blocking Radio waves and magnetic. Another cost-effective material is Nickel that can be used on its own or in combination with other metals to form magnetic alloys.

Importance of EMI Shielding

EMI shielding is crucial for numerous reasons. For manufacturers, shielding is important to ensure the reliability and performance of the company’s product. If a particular electronic device is not properly shielded, it will continuously fail and that won’t impact the reliability and reputation of the company. Employees and professionals dealing with large amounts of big data or confidential data may also need shielding because EMI can jeopardize their access to crucial information.

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