4 Differences Between Thermally and Electrically Conductive Elastomers

2. Composition

The composition of electrically and thermally conductive elastomers differs significantly due to their distinct functional requirements. Both materials consist of an elastomeric polymer matrix infused with conductive fillers, but the choice of fillers and their distribution determine whether the material conducts electricity or heat.

Electrically Conductive Elastomers

Electrically conductive elastomers rely on conductive fillers such as silver, nickel, copper, or carbon-based materials like carbon black and graphene. These fillers create a percolation network within the polymer matrix, allowing electrons to move freely and enabling electrical conductivity. The polymer base, typically silicone, fluorosilicone, or EPDM, provides flexibility and durability while ensuring environmental resistance.

Silver-filled silicones are widely used in EMI shielding applications due to their high conductivity, whereas carbon-loaded elastomers offer a cost-effective alternative for applications requiring moderate conductivity. The key factor in these elastomers is achieving a balance between conductivity and mechanical integrity, ensuring that electrical performance is maintained even under compression or environmental stress.

Thermally Conductive Elastomers

Thermally conductive elastomers, on the other hand, incorporate thermally conductive but electrically insulating fillers such as boron nitride, aluminum oxide, or alumina. These materials enhance heat transfer by forming a thermal pathway through the elastomer while preventing electrical conduction. The elastomer base—often silicone—remains flexible, allowing the material to conform to surfaces and fill gaps between heat-generating components. Unlike electrically conductive elastomers, which require a continuous conductive network, thermally conductive elastomers optimize filler alignment to maximize heat dissipation without compromising dielectric strength.

Thus, while both elastomers rely on conductive fillers, their composition is tailored to prioritize either electrical conductivity or thermal efficiency.

3. Properties

Electrically and thermally conductive elastomers exhibit distinct properties due to their differing functional priorities. While both materials maintain flexibility, durability, and resistance to environmental factors, their conductivity, mechanical behavior, and performance characteristics diverge significantly.

Electrically Conductive Elastomers

Electrically conductive elastomers are designed to facilitate the flow of electrical current while maintaining mechanical integrity. Their key properties include low electrical resistance, high EMI shielding effectiveness, and stable conductivity under compression.

ECEs must form a continuous conductive network, ensuring reliable signal transmission and electromagnetic protection even when subjected to mechanical stress. They also offer good environmental resistance, with silicone-based variants providing excellent temperature stability and resistance to moisture, chemicals, and UV exposure. However, because metal fillers like silver or nickel are commonly used, electrically conductive elastomers may be prone to oxidation or increased stiffness over time, requiring careful formulation to balance conductivity and flexibility.

Thermally Conductive Elastomers

Thermally conductive elastomers, by contrast, prioritize efficient heat dissipation without conducting electricity. Their key properties include high thermal conductivity, electrical insulation, and compressibility, allowing them to conform to surfaces for effective thermal transfer.

TCEs function as thermal interface materials (TIMs), bridging gaps between heat-generating components and heat sinks while preventing electrical short circuits. They typically exhibit higher mechanical softness than electrically conductive elastomers, ensuring optimal contact for efficient heat transfer. Additionally, their resistance to thermal degradation makes them ideal for high-temperature applications, particularly in power electronics and LED cooling systems.

Ultimately, the primary distinction lies in conductivity: electrically conductive elastomers optimize electrical performance, while thermally conductive elastomers enhance heat management without compromising insulation.

4. Applications

Electrically and thermally conductive elastomers serve distinct purposes in various industries, primarily differing in their conductive properties and applications.

Electrically Conductive Elastomers

Designed to facilitate the flow of electrical currents, electrically conductive elastomers are often used in applications where electromagnetic interference (EMI) shielding, grounding, or static dissipation is necessary. ECEs are commonly found in electronic enclosures, computer devices, and components that require protection against electromagnetic radiation. They are also used in automotive, aerospace, and telecommunications industries to reduce electrical noise and ensure the safety and reliability of electronic systems.

Thermally Conductive Elastomers

Engineered to transfer heat efficiently while maintaining flexibility, thermally conductive elastomers are used in applications that require heat dissipation, such as in electronic devices, power supplies, or LED lighting systems. They are widely used in thermal management solutions, ensuring that devices remain within safe temperature limits to prevent overheating and failure. TCEs are also employed in automotive and industrial applications to manage heat in machinery or engine components.

Conclusion

While electrically and thermally conductive elastomers may appear similar in structure, they differ in their purpose, composition, properties, and application. Electrically conductive elastomers are built to maintain signal integrity and provide EMI/RFI shielding in environments where electronic performance is critical. Thermally conductive elastomers, on the other hand, are engineered to dissipate heat efficiently while maintaining electrical insulation—an essential requirement in managing thermal loads for compact, high-performance systems.

By understanding these differences, you can make informed material choices that align with your specific design and performance requirements. Whether your focus is on electromagnetic shielding or thermal management, selecting the right elastomer is key to ensuring long-term reliability and optimal system functionality.

For further insights, consider reading our article on 4 Things to Consider When Choosing a Conductive Elastomer.

The ID Group has a long history of supporting engineers and procurement specialists across Canada with standard and custom high-performance EMI/RFI shielding and thermal management solutions. If you have questions about conductive elastomers, whether electrical or thermal, we’re here to help. Get in touch with our team today.