5 Most Common Types of EMI Shielding Gaskets

Types of EMI Shielding Gaskets

5 Most Common Types of EMI Shielding Gaskets

EMI and RFI interferences are expressions of the electromagnetic spectrum that disrupt the functionality of electronic devices and systems by introducing noise, stray currents, and signal errors. One effective way to limit these interferences is through EMI RFI shielding gaskets, which provide barriers against unwanted signals by capturing the interference and carrying it to the ground before it can have an unwanted influence. Various types of EMI shielding gaskets are available, from conductive elastomers to fingerstock designs, each offering specific advantages for different applications and environmental conditions.

Let’s take a look at the five most common types of shielding gaskets that help protect equipment such as military and highly sensitive medical imaging and diagnostic equipment from EMI.

1. Fingerstock Gaskets

EMI shielding fingerstock gaskets, also called shielding strips, are thin, spring-like elements made from Beryllium Copper or similar low-resistivity and springy metals. These EMI shielding gaskets are designed to provide excellent electrical conductivity, high contact quality, and mechanical flexibility, making them ideal for EMI/RFI shielding in enclosures with high-frequency requirements. Also known as fingerstock gaskets, these can be designed to fit various applications and formats.

Applications:

  • Electronics cabinets and enclosures, acting as flexible contact fingers to bridge between elements of the enclosure and inspection panels, to provide gap closure and electrical/shielding continuity. This helps in protecting sensitive electronic equipment from interference.
  • Communication systems, shielding connectors and assembly points where continuity can be challenged or gaps hard to bridge. This ensures signal integrity in military, aerospace, and telecommunication equipment.

Advantages:

  • High conductivity and small gaps deliver shielding effectiveness across a broad frequency range.
  • Excellent resilience to repeated compression and relaxation and long-term compression.
  • Compatibility with harsh environments due to intrinsically low-corrosion materials, enhanced by corrosion-resistant coatings of Nickel or Tin.

Fingerstock gaskets can be mounted in various configurations to fit different designs. To explore more about these options, see our previous article on fingerstock gasket mounting options.

2. Metalized Fabric Over Foam Gaskets

Metalized fabric gaskets over foam cores (FOF) are constructed from a conductive fabric layer wrapped around a compressible foam core. These gaskets provide a lower-cost and more lightweight EMI shielding solution than fingerstock gaskets, suited to applications requiring moderate shielding performance.

Applications:

  • Shielding enclosure/housing gaps in laptops, smartphones, and other devices.
  • Used in automotive infotainment systems and electronic control/engine management modules.
  • Shielding server racks and network hardware in data and processing installations.

Advantages:

  • Highly flexible and compressible, which allows them to handle both larger gaps and more irregular spaces.
  • Lightweight, which is valuable in portable electronics and automotive designs.
  • Cost-effective compared to many other gasket types.

Metalized fabric gaskets are produced in various shapes and overall thicknesses, including rectangular profiles, hollow tubes, and custom designs, allowing adaptive design to suit complex assemblies.

3. Mesh Gaskets

Mesh EMI shielding gaskets are made from fabric woven from metal wires, manufactured from materials such as stainless steel, Monel, and Aluminum. These types of EMI shielding gaskets combine a high standard of shielding effectiveness with mechanical durability, making them ideal for high-performance EMI shielding applications that also require low weight.

Applications:

  • Protecting mission-critical systems from interference.
  • Shielding large control-system cabinets and housings in demanding environments.
  • Ensuring compliance with strict EMI/RFI regulations to preserve signal quality and contain unintentional transmissions.

Advantages:

  • Superior shielding effectiveness at low and high frequencies.
  • Durable construction suitable for extreme environmental conditions.
  • Highly customizable for large and irregular openings.

Mesh gaskets are frequently combined with elastomer or compressible foam cores to create a dual-purpose solution that enhances both EMI shielding and environmental sealing. This integration allows the gasket to conform effectively to complex geometries and variable gap sizes while maintaining consistent electrical contact and providing reliable protection against environmental factors.

4. Conductive Foam Gaskets

Conductive foam gaskets are made from polyurethanes or similar foam materials, impregnated with conductive particles such as Silver, Nickel, or Carbon. These gaskets offer a compressible, lightweight shielding solution suitable for delicate applications. They typically use non-curing conductive adhesives for attachment and continuity.

Applications:

  • Printed circuit boards (PCBs) commonly employ shielding between layers or components for highly localized interference protection.
  • Portable and wearable devices require compact and lightweight shielding in laptops, tablets, and lightweight medical equipment and monitors.

Advantages:

  • Great flexibility and lightweight.
  • Easy to install and remove without damaging delicate components.
  • Cost-effective, light and easily installed for applications requiring moderate shielding performance.

Many conductive foam EMI shielding gaskets are thermally conductive and thus provide dual functionality, offering thermal dissipation along with EMI shielding. This is invaluable in heat-sensitive electronics in space-challenged settings.

5. Conductive Elastomer Gaskets

Conductive elastomer gaskets are manufactured from silicone rubber or other elastomeric polymers combined with conductive filler materials such as Silver-plated Aluminum or Nickel-coated graphite microbeads. These EMI shielding gaskets are specified for the dual purpose of robust EMI shielding and dust/water/gas ingress prevention in a single, robust component.

Applications:

  • Defense and aerospace applications use these gaskets to protect avionics and communication systems likely to encounter wet environments.
  • Automotive applications use this approach for shielding electronic control units (ECUs), onboard computers, and sensors.
  • Medical equipment uses this type of shield gasket for ensuring EMI compliance in life-critical, wet area devices such as implants for arrhythmia control and automated drug dispense.

Advantages:

  • Excellent shielding performance across a wide frequency range.
  • Resilient to harsh environmental conditions, including extreme temperatures, humidity, and chemical exposure.
  • Long lifespan with minimal degradation or relaxation of contact over long use/compression.

Conductive elastomer gaskets can be transferred or injection molded, stamped from flat sheet, or extruded into complex and compliant section shapes to suit the needs of specific applications.

Conclusion

EMI shielding gaskets are critically important in protecting the function of electronic systems from the spectrum of electromagnetic interference, allowing error-free signals and processing and regulatory/certification compliance.

Ranging from high-performance fingerstock gaskets to more cost-effective and lower-performing conductive foam elements, each type offers particular benefits and suits varied application limitations/demands. Selecting the right gasket requires a deep understanding of the actual operational environment and device sensitivities, susceptibility, and emission shielding compliance requirements, and the practical design constraints that apply. Implementation of an appropriate shielding solution helps maintain the reliability and operational safety of devices and systems in the face of potentially serious electromagnetic interference challenges.

Need help selecting the right EMI shielding solutions for your next project? As a Canadian distributor of EMI solutions, The ID Group provides access to customized solutions across all these gasket types, working closely with clients to determine the most effective shielding approach for their specific applications. Contact us today to discuss your requirements and find out how our EMI gasket solutions can help enhance your product’s performance.