Electromagnetic shielding, also known as electromagnetic compatibility, it is a technology used to prevent EMI and EMR from affecting electronic equipment and systems.The main purpose of electromagnetic shielding is to improve the performance and reliability of equipment and ensure its normal operation.
The principle of electromagnetic shielding is mainly based on two mechanisms: reflection loss and absorption loss.
Reflection Loss: When electromagnetic waves are incident on the surface of the shield, due to the conductivity of the shield, the electromagnetic waves will be reflected on its surface, thereby reducing the electromagnetic wave energy entering the shield.
Absorption Loss: Part of the electromagnetic waves incident on the shield will be absorbed inside the material and converted into heat energy, further reducing the propagation of electromagnetic waves.
EMI shielding materials can be classified according to the principles of reflection and absorption.
Electromagnetic shielding materials based on the reflection principle are mainly metal materials with good electrical conductivity. These materials can effectively reflect electromagnetic waves, thereby reducing electromagnetic interference. Reflective shielding materials include:
Copper: Copper has excellent electrical conductivity and reflectivity，and is widely used in electromagnetic shielding applications.
Aluminum: Aluminum is light and has good reflective properties, such as Shielded aluminium honeycomb vent, which have the characteristics of high shielding efficiency, large ventilation volume and light weight.
Steel: Although steel is not as conductive as copper and aluminum, its corrosion resistance and strength make it still very effective in certain applications. For example, Steel Honeycomb Ventilation Panels have the characteristics of large ventilation volume, firmness, non-deformation, strong resistance to mechanical impact, and broadband high shielding effectiveness. They are particularly suitable for equipment and facilities such as chassis (cabinets), electronic shelters, and shielded rooms with high shielding effectiveness requirements and harsh application environments such as impact and vibration resistance.
Galvanized steel: Galvanized steel can provide a certain electromagnetic shielding effect while preventing rust.
Wire mesh: Wire mesh (such as copper mesh or aluminum mesh) can be used for shielding, especially when ventilation or heat dissipation is required. Wire mesh has good conductivity, lightness, and corrosion resistance, such as Knitted wire mesh gasket.
Absorption-based electromagnetic shielding materials are mainly materials that can absorb electromagnetic wave energy and convert it into heat energy. These materials usually have high dielectric loss and magnetic loss, and can effectively reduce the intensity of electromagnetic waves.
Absorptive shielding materials include:
Conductive elastomer: such as silicone rubber or fluorosilicone rubber containing conductive particles. It combines the environmental sealing properties of silicone rubber itself with the high conductivity of conductive particles, which can not only meet the requirements of conductive grounding and electromagnetic shielding, but also achieve environmental sealing.
Carbon-based materials: such as carbon fiber, graphene, etc., these materials have good conductivity and absorption characteristics.
Ferrite materials: Ferrite is a ceramic material with magnetic and electrical conductivity, which can effectively absorb high-frequency electromagnetic waves.
Absorbent coatings: These coatings usually contain conductive or magnetic particles and can be coated on the surface of the device to absorb electromagnetic waves, such as
ITO layer shielded windows.
Foam materials: Some special foam materials (such as conductive foam) can also be used to absorb electromagnetic waves.
Nowadays, various electronic devices are increasingly used in people's lives and work. But electronic devices will generate electromagnetic radiation during operation, which may have adverse effects on people's health. EMI between devices will also cause signal interception and data loss, which will seriously affect the performance of electronic devices and their normal operation. Especially with the development of the Internet of Things, autonomous driving, and wearable devices, electronic devices are becoming more and more complex, smaller in size, and more and more demanding in precision. To ensure the normal operation of these highly integrated, high-power electronic devices, EMI shielding is essential.
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