Key Takeaways
What is a conductive silicone elastomer?
A conductive silicone elastomer is an engineered material that blends a flexible silicone or fluorosilicone polymer matrix with conductive metallic or carbon filler particles (such as silver-plated aluminum, nickel-graphite, or carbon black). It provides dual-function performance: environmental sealing (moisture, dust, extreme temperatures from -55°C to +200°C and continuous electrical conductivity for Electromagnetic Interference (EMI) and Radio Frequency Interference (RFI) shielding.
What Are Conductive Silicone Elastomers?
Conductive silicone elastomers combine the physical flexibility, resilience, and environmental resistance of silicone rubber with the electrical conductivity of specialized filler materials.
In demanding applications across aerospace, defense, medical devices, automotive electronics, and telecommunications, standard rubber seals are insufficient. Electronics require both environmental protection against weather, fuels, and chemicals, and protection against electromagnetic interference (EMI). Conductive silicone elastomers bridge this gap by establishing an electrically continuous path across mating surfaces while maintaining a tight environmental seal.
Conductive Filler Materials & Comparison
The electrical performance, mechanical strength, corrosion resistance, and cost of a conductive silicone elastomer are determined primarily by its filler material.
While generic conductive elastomers can use carbon-based or polymeric fillers, industrial EMI/RFI shielding silicones typically rely on metallic and metal-coated particles to meet strict attenuation standards (such as MIL-DTL-83528).
| Filler Type | Typical Applications | Shielding Effectiveness (dB) | Volume Resistivity (Ω⋅cm) | Temperature Range | Relative Cost |
| Nickel-Graphite (Ni/C) | Commercial & Military EMI Gaskets, Galvanic Corrosion Resistance | 80 – 100 dB | < 0.010 | -55°C to +160°C | Moderate |
| Silver-Plated Aluminum (Ag/Al) | MIL-DTL-83528 Aerospace & Defense Electronics | > 100 dB | < 0.008 | -55°C to +160°C | High |
| Silver-Plated Copper (Ag/Cu) | High-Attenuation EMP / High-Frequency EMI Seals | >110 dB | < 0.002 | -55°C to +125°C | High |
| Silver-Plated Glass (Ag/G) | Lightweight Commercial Enclosures, Connector Gaskets | 70 – 90 dB | < 0.010 | -55°C to +160°C | Moderate |
| Carbon Black / Graphite | Electrostatic Discharge (ESD) Protection, Anti-Static Seals | 20 – 40 dB | 1 – 100 | -55°C to +200°C | Economical |
https://sspinc.com/emi-gaskets/Essential Properties of Conductive Silicone Elastomers
When selecting a conductive silicone elastomer for an EMI gasket, consider these core mechanical and electrical properties:
Volume Resistivity (Ω⋅cm): Measures electrical resistance through the bulk material. Lower values indicate higher electrical conductivity.
Shielding Effectiveness (dB): Measures the material’s ability to attenuate incoming or outgoing electromagnetic radiation across specific frequency bands 10 MHz to 10 GHz per ASTM D4935 or MIL-DTL-83528 testing.
Durometer (Hardness): Available in soft to firm formulations (typically 30 to 80 Shore A). Lower durometer formulations ensure low compression force while maintaining seal integrity on delicate enclosures.
Thermal Stability & Operating Range: Standard silicone-based conductive elastomers maintain flexibility and conductivity across operating temperatures from -55°C to +200°C.
Fluid and Chemical Resistance: When exposed to jet fuels, solvents, or hydraulic fluids, fluorosilicone base polymers are substituted for standard silicone to prevent swelling and material degradation.
Industry Applications
Aerospace & Defense: Connector gaskets, wave-guide gaskets, radar enclosures, and avionics seals meeting MIL-DTL-83528 slash sheet specs.
Automotive & EV: Battery management system (BMS) shielding, anti-static components, radar sensors, and ECU seals.
Medical Electronics: Wearable bio-sensors, shielded enclosures for diagnostic imaging, and low-outgassing seals.
Telecommunications: 5G base station enclosures, outdoor electronics enclosures, and flexible circuit shielding.
Frequently Asked Questions (FAQ)
What is the difference between conductive silicone and conductive fluorosilicone?
Standard conductive silicone offers excellent temperature resistance, UV stability, and flexibility, making it ideal for general indoor and outdoor EMI shielding. Conductive fluorosilicone provides the same electrical conductivity and physical flexibility but adds high resistance to aggressive chemicals, jet fuels, oils, and solvents—making it essential for aerospace, military, and automotive applications.
How do conductive silicone elastomers provide EMI shielding?
Conductive silicone elastomers contain a dense network of microscopic conductive particles (such as silver, nickel, or carbon). When compressed in an enclosure joint, these particles form a continuous pathway that reflects and absorbs electromagnetic radiation, preventing high-frequency noise from entering or leaking out of the device.
How do I prevent galvanic corrosion when using conductive silicone gaskets?
To prevent galvanic corrosion between aluminum enclosures and conductive gaskets, select filler materials with compatible electrochemical potentials. Nickel-graphite (Ni/C) and silver-plated aluminum (Ag/Al) fillers are specifically engineered to minimize galvanic action when mated against aluminum alloy housings.
