Conductive Silicone Extrusions for EMI and RFI Shielding

As electronic devices become more powerful and densely packed, managing electromagnetic interference (EMI) and radio frequency interference (RFI) has become critical across industries. Conductive silicone extrusions offer an elegant solution — combining the environmental sealing properties of silicone rubber with the electrical conductivity needed to block unwanted electromagnetic energy.

At MOR Industries, we manufacture custom conductive silicone extrusions engineered to meet the demanding requirements of EMI and RFI shielding applications.

What Is EMI/RFI Shielding?

Electromagnetic interference and radio frequency interference are unwanted electromagnetic signals that can disrupt the operation of electronic equipment. Left unmanaged, this interference causes signal degradation, data corruption, equipment malfunction, and failure to meet regulatory compliance standards.

Effective shielding requires creating a continuous conductive barrier — often called a Faraday cage — around sensitive electronics. Any gap in this barrier, such as a seam between two enclosure panels, becomes a leak point for electromagnetic energy. This is where conductive silicone gaskets and extrusions play their essential role: sealing the gaps while maintaining electrical continuity across the joint.

How Conductive Silicone Works

Standard silicone rubber is an electrical insulator. To make it conductive, we incorporate conductive fillers into the silicone base compound. These fillers create a continuous electrical pathway through the material, allowing it to conduct electricity and reflect or absorb electromagnetic energy.

Conductive silicone falls into two broad categories, and choosing the right one is the single most important decision in any shielding application.

Carbon-Filled Conductive Silicone

Carbon-based conductive silicone uses conductive carbon black as the filler. These compounds are always black in appearance and offer good conductivity, with a volume resistivity typically around 10⁻³ ohm-centimetres. Established grades such as Wacker Elastosil R 573 fall into this category — a platinum-cured, high-consistency silicone well suited to conductive profiles, EMI gaskets, ignition cable cores, band electrodes, and antistatic applications.

Carbon-filled silicone is the cost-effective choice for applications requiring moderate shielding, static dissipation, and reliable environmental sealing. It offers an excellent balance of performance and value for the majority of general shielding requirements.

Metal-Filled Conductive Silicone

For applications demanding the highest levels of shielding effectiveness, metal-filled conductive silicone can be supplied on request. These compounds use conductive metal fillers to achieve a much lower volume resistivity, typically in the range of 10⁻⁴ to 10⁻⁵ ohm-centimetres — significantly more conductive than carbon-filled grades.

Metal filler systems can include silver-plated aluminium, silver-plated copper, silver-plated glass, nickel-coated graphite, or pure silver particles, each offering a different balance of conductivity, weight, and cost. These grades are typically specified where high shielding effectiveness is essential, such as military, aerospace, and high-frequency telecommunications equipment.

If your application calls for this level of performance, talk to our team and we can source the appropriate metal-filled compound to suit your requirements.

Choosing the Right Compound

The right choice depends on the level of shielding effectiveness the application demands, balanced against budget. Carbon-filled grades deliver dependable performance for antistatic and moderate EMI shielding needs and cover the majority of general shielding requirements, while metal-filled grades are available on request for the most demanding environments. Our technical team works with customers to select the optimal filler system for each application, ensuring you get the right level of performance without over-specifying.

Key Advantages of Conductive Silicone Extrusions

Conductive silicone extrusions combine several critical properties in a single material, which is why they have become a preferred choice for EMI/RFI shielding.

Dual functionality — They provide both environmental sealing and electromagnetic shielding simultaneously, eliminating the need for separate seals and shielding components.

Wide temperature range — Silicone maintains its flexibility and performance across an exceptionally broad temperature range, typically from -55°C to +200°C, making it suitable for aerospace, military, and industrial environments.

Environmental resistance — Silicone offers excellent resistance to UV, ozone, moisture, and weathering, ensuring long-term performance in outdoor and harsh environments.

Compression set resistance — Quality conductive silicone maintains its sealing force over time, ensuring the shielding integrity is preserved throughout the service life of the equipment.

Custom profiles — Extrusion allows for virtually unlimited profile geometries, from simple O-profiles and D-sections to complex multi-lipped designs tailored to specific enclosure requirements.

Common Applications

Conductive silicone extrusions are used across a wide range of industries where electromagnetic compatibility is essential.

Aerospace and Defence

Military and aerospace electronics operate in environments with strict EMI/RFI requirements. Conductive silicone gaskets seal avionics enclosures, radar systems, communication equipment, and electronic warfare systems, protecting against both interference and environmental exposure at extreme altitudes and temperatures.

Telecommunications

Base stations, signal processing equipment, and network infrastructure rely on conductive silicone seals to prevent interference between components and to maintain signal integrity. As 5G networks expand, the demand for effective high-frequency shielding continues to grow.

Medical Equipment

Sensitive diagnostic and monitoring equipment such as MRI machines, patient monitors, and imaging systems must be shielded from external interference and must not emit interference that could affect other devices. Conductive silicone provides shielding while meeting the cleanliness and biocompatibility standards of medical environments.

Industrial Electronics

Control cabinets, variable frequency drives, power supplies, and automation equipment in industrial settings generate and are susceptible to electromagnetic interference. Conductive silicone seals protect these systems while withstanding dust, moisture, and temperature extremes on the factory floor.

Data Centres and Computing

Server enclosures, networking hardware, and high-performance computing systems use conductive silicone shielding to prevent crosstalk and maintain data integrity in densely packed electronic environments.

Automotive and Electric Vehicles

Modern vehicles contain extensive electronic systems, and electric vehicles in particular generate significant electromagnetic energy from their power electronics. Conductive silicone seals shield sensitive control units, battery management systems, and charging electronics.

Selecting the Right Conductive Silicone Profile

Choosing the correct conductive silicone extrusion requires balancing several factors:

Shielding effectiveness — Measured in decibels (dB), this indicates how much electromagnetic energy the material blocks. Requirements vary by application and frequency range.

Environmental sealing — The profile geometry and material hardness must provide the required seal against moisture, dust, and other contaminants (often specified as an IP rating).

Compression range — The gasket must be designed to work within the available compression range of the enclosure design, maintaining both electrical contact and environmental seal.

Galvanic compatibility — The conductive filler must be compatible with the mating flange material to prevent galvanic corrosion at the interface.

Profile geometry — The cross-section must suit the enclosure design, whether that requires a simple solid profile, a hollow section for lower closure force, or a complex multi-function design.

Why Choose MOR Industries

With over a century of rubber extrusion and moulding expertise, MOR Industries brings deep technical knowledge to every conductive silicone project. We work closely with our customers to understand their shielding requirements, environmental conditions, and enclosure designs, then engineer a custom extrusion solution that delivers reliable performance.

Our capabilities include custom profile development, material selection guidance, and manufacturing to tight tolerances. Whether you need a standard profile or a fully bespoke design, our team can help you achieve effective, durable EMI/RFI shielding.

Get in Touch

If you have an EMI/RFI shielding application and want to explore how conductive silicone extrusions can solve your electromagnetic compatibility challenges, contact the MOR Industries team today. We are happy to discuss your requirements and develop a solution tailored to your needs.

MOR Industries — Custom Rubber Extrusion and Moulding. Proudly manufacturing in Australia.