EMI Shielding
Electromagnetic interference, commonly known as EMI, refers to disruptive electromagnetic radiation emitted from electronic devices that can interfere with other nearby equipment. This interference can cause technical issues ranging from temporary glitches to permanent damage of sensitive electronic components. Growing concern over EMI has fueled the growth of the EMI shielding materials aimed at blocking these disruptive electromagnetic waves. They play a vital role in ensuring smooth functioning of various electronic systems by protecting them against external electromagnetic radiations.
Types
A wide variety of materials are used for EMI shielding depending on the requirements and applications. Some of the major types are:
Metals as EMI Shielding Materials
Metals are the most widely used them due to their excellent conductivity. Common metal options include copper, aluminum and steel. Copper offers the best conductivity for effective EMI Shielding Materials is more expensive than aluminum. Steel is low cost but less conductive. Often metal plates, foils or meshes are used to form EMI shielding enclosures.
Conductive Coatings for EMI Shielding
Conductive coatings containing metal particles like silver, nickel or carbon are applied on non-conductive substrates to impart EMI shielding properties. Epoxy or acrylic based conductive coatings are used to shield components which cannot use metal EMI shielding due to weight or fabrication constraints. These coatings offer over 90% shielding effectiveness.
Carbon-Based EMI Shielding Materials
Carbon nanotube (CNT), graphene and conductive polymer composites have emerged as promising shielding materials. CNT composites exhibit excellent EMI shielding ability when blended with polymers or coatings. Graphene, a thin layer of carbon atoms arranged in a honeycomb lattice, can effectively block EMI waves. Conductive polymers loaded with carbon particles also serve as lightweight and flexible shielding materials.
Fabric Shields for Flexible EMI Shielding
Conductive fabric inserts loaded with silver, nickel or carbon provide flexible shielding solutions. Woven metal mesh fabrics, conductive polymer coated fabrics and CNT blended fabrics enable conformal shielding of complex three-dimensional assemblies and eliminate need for rigid metallic enclosures. These fabric shields are stretchable, foldable and eliminate need for grounding.
How EMI Shielding Materials Work
All conducting materials, whether metal or coating, work on the same principle to block electromagnetic interference. When EMI waves interact with these materials, electrons inside their atomic structure are disturbed and forced to oscillate by the alternating electromagnetic fields.
The mechanical oscillation of a huge number of electrons helps create opposing electromagnetic fields that cancel out the incoming EMI waves. This disruption and cancellation of waves is known as reflection. In metals, free electrons can move easily which enables quicker generation of opposite fields for highly effective EMI shielding. Materials with higher electrical conductivity have more free electrons and thus better shielding capabilities.
Another phenomena involved is absorption where some portion of the incoming EMI energy gets converted into other forms like heat due to resistance offered by the shielding material during oscillation of electrons. Both reflection and absorption combine to limit wave penetration and shield the equipment from electromagnetic interference. Proper grounding of EMI shields promotes effective reflection of waves for maximum protection.
Functions of EMI Shielding
The primary function of all EMI shielding materials is to provide a continuous conducting barrier that blocks electromagnetic waves from entering or escaping an electronic device. Besides this, there are some important secondary functions served by EMI shielding:
- Protects sensitive circuits from malfunction or damage due to external EMI
- Prevents emission of electromagnetic interference from internal electronics to meet regulatory norms
- Reduces electromagnetic coupling between circuits within complex systems
- Shields computers and communication devices from wireless signals for data security
- Blocks radio frequency ID (RFID) or near field communication (NFC) signals as per application needs
- Provides surge protection to electronic boards against electrostatic discharge or lightning
- Absorbs electromagnetic energy to eliminate reflection and multipath distortion problems
Rapid advancements in electronics demand highly effective EMI shielding solutions to ensure seamless co-existence of numerous devices in the limited electromagnetic spectrum. With continuous innovation, EMI shielding materials will continue to play a critical role in maintaining the optimal performance and reliability of electronic systems.
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Ravina Pandya, Content Writer, has a strong foothold in the market research industry. She specializes in writing well-researched articles from different industries, including food and beverages, information and technology, healthcare, chemical and materials, etc. (https://www.linkedin.com/in/ravina-pandya-1a3984191)
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