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EMI Gasket Materials and Application
An EMI gasket is typically designed to seal the space between two surfaces, reducing electromagnetic interference from leaking out or getting into a shielded device. In order to do this, these gaskets must be made from materials that can provide effective shielding. In this post, you’ll learn about these EMI gasket materials and when to use them.
Table of Contents
What is EMI Gasket?
An EMI gasket is a type of shielding material used to provide an electromagnetic barrier between two surfaces. It’s typically designed to prevent any type of electromagnetic interference (EMI) from leaking out or getting into the device being shielded.
EMI gaskets and seals come in different designs. They can be flat sheets made from conductive materials like metal or metal filed rubber, or they can be a foam material that is compression-molded into any shape to fit a specific design requirement.
Depending on the application also, an EMI shielding gasket can be made from a single type of material or from multiple materials. More about the EMI gasket materials later; for now, let’s take a look at how these shielding and sealing pieces work.
How do EMI Gaskets Work?
An EMI gasket is an electromagnetic interference shield like any other only that it serves to fill the space between two or more EMI shield components. This may be the openings of an EMI enclosure or the spaces between EMI shielding panels and doors.
An EMI shielding gasket usually does not only block interference waves, but it also provides other benefits such as environmental sealing and thermal insulation. This involves preventing the entry of dust, moisture, or water into the shielded area.
EMI gaskets can come in many forms such as strips, rings, finger stock, and so on. They are usually made from conductive materials that offer both shielding and environmental sealing performance.
In terms of applications, the EMI shield gasket is used in everything from consumer electronics and telecommunication systems to aerospace and automotive industries. They are also particularly useful in medical and healthcare applications, where shielded structures help protect people or equipment.
EMI Gasket Materials
Different materials are used to make EMI gaskets and seals. Some of them are more common than other, while some are more costly or more effective. Here, we’ve provided a list of five most used EMI gasket materials and their key characteristics.
Beryllium Copper EMI shielding Gaskets
These shielding gaskets are made from an alloy of copper and beryllium, which provides excellent conductivity and EMI shielding properties of up to 165 dB. This material also provides exceptional corrosion resistance and environmental sealing.
In addition to the various design options, beryllium copper EMI shielding gaskets offers different attachment methods such as clip on, riveting, adhesive bonding, and soldering, among others.
Beryllium copper EMI gaskets are often a preferred material for aerospace and medical due to their superior properties. In these applications, the gaskets are often groove mounted types for better sealing performance.
Conductive Elastomer Gaskets
This EMI rubber gasket is typically made from a combination of rubber and metal wires or particles such as silver, aluminum, and nickel or other conductive materials like graphite.
Common versions include silicone elastomer, ethylene-propylene diene monomer, and fluorosilicone EMI gasket. The type to use depends on various factors, such as the required level of protection ability to withstand the environment, among other requirements.
A conductive elastomer gasket will easily take the shape of the surface it’s being applied to. It also provides good vibration damping, environmental sealing and (depending on the conductive material used), resistance to corrosion.
EMI Mesh Gasket
One of the most used EMI gasket materials is mesh. This is a woven material consisting of metal wires that provides electrical conductivity for shielding effectiveness. Mesh EMI gaskets are available in different sizes and densities, as well as different shapes.
To allow for size flexibility, a knitted wire mesh EMI shielding gasket should is also often used with a urethane or silicone elastomer material inside the mesh to conform it to irregular surfaces. Applications for the EMI wire mesh gasket include RF applications, medical equipment, and aerospace components
EMI Foam Gasket
EMI foam gaskets are made from an open-cell or closed cell, conductive material. This makes them lightweight and highly flexible for easy installation. The foam is usually infused with conductive particles, such as copper or silver, to make it a shielding material for electromagnetic waves.
The foam allows for great flexibility and an improved ability to conform to surfaces. In addition, this is one of the few EMI gasket materials that provide lightweight shielding.
EMI gasket foam, when used to seal electrical enclosures, must provide environmental properties as well, in addition to its ability to provide EMI shielding.
Fabric over Foam EMI Gasket
This is EMI shielding gasket material is simply a combination of conductive fabric and foam, and often used in applications that require both flexibility and shielding effectiveness. The fabric provides the electrical conductivity while the foam adds flexibility.
A fabric over foam EMI gasket can also be customized for different shapes and sizes, depending on your application requirements. These EMI gasket materials also provide excellent shielding performance, and the fabric can be treated to improve its durability.
Custom EMI Gaskets
In addition to the EMI gasket materials and shield designs mentioned, users can also opt for custom gaskets. Custom EMI gaskets are designed to meet the specific demands of your application, such as size, shape and material.
These gaskets are often used in difficult-to-shield environments where a standard solution may not work for an effective shielding performance. The custom design can provide better flexibility or improved environmental protection, for example, in addition to the shielding properties.
EMI gasket manufacturers will usually be able to provide you with the right material and design for your application, ensuring maximum shielding performance. That also includes helping you ensure the gasket or shielding meets all required EMC standards.
Conclusion
An EMI gasket is essential component of many electrical and electronic devices. In addition to providing shielding, these shields also act as seals in situations where structures contain openings that might allow EMI in or out. The type of EMI gasket material you choose will depend on your application requirements. That being said, different options are available to suit a variety of needs, from conductive rubber to fabric-over-foam gasket