Elastomer Seals for Conductive EMC Shielding

ELECTRICALLY CONDUCTIVE ELASTOMER SEALS

In electronic assemblies, elastomer seals often serve more than just a sealing function. As electrically conductive elastomer seals, they protect housings, interfaces, and contact surfaces from electromagnetic interference while also sealing them off from environmental influences.

E.S. Electronic Service helps you select the right EMC gaskets for your application. As a Parker Chomerics service center, we offer CHO-SEAL materials in a variety of designs, material grades, and profiles. This ensures you receive a solution that is electrically, mechanically, and structurally compatible with your design.

Electrically Conductive Elastomer Seals in Use: What They Do and Where They Work

Electrically Conductive Elastomer Seals They are used wherever housings, covers, frames, or interfaces must seal reliably. They compensate for mechanical tolerances while also establishing a conductive connection between contact surfaces. In this way, they help limit electromagnetic interference at critical interfaces. Especially in the EMI shielding That is why they are more than just a simple sealing profile. They combine sealing, electrical contact, and shielding functions in a single component.

Typical applications can be found wherever electronics need to be protected, stabilized, or cleanly isolated:

Electronics Enclosures and Control Units: Conductive elastomer seals seal enclosure joints and reduce interference paths at covers, seams, and interfaces.

Measurement and Analysis Instruments: Conductive seals at housing joints and end caps help ensure stable measurement conditions for sensitive signals.

Communication Modules and RF Assemblies: In compact assemblies, they ensure conductive connections and integrate shielding concepts seamlessly into the design.

Automotive and Industrial Systems: In the face of vibration, temperature fluctuations, and limited installation space, these materials combine sealing performance with reliable EMC functionality.

Special Geometries and Circumferential Sealing Configurations: If standard profiles are not sufficient for the design requirements, spliced O-rings or frame seals can be adapted to the required configuration.

Technically, a conductive EMC gasket consists of an elastic polymer and electrically conductive particles. The polymer provides the rubber-like structure, the deformability, and the sealing effect. The particles establish the electrical connection and contribute to the shielding effect. Where an elastic gasket is not practical, Electrically conductive adhesives and sealants Add transitions, seams, or contact points. The appropriate solution depends primarily on the housing material, compression, contact surface, and assembly process.

ELECTRICALLY CONDUCTIVE ELASTOMER SEALS

	Elastomers	Filler	Volume resistivity (ohm-cm)	Hardness (Shore A)	Use temperature (°C)	Comments	Technical data sheets
CHO-Seal 1221	Fluorosilicone	Ag	0,002	75+/-5	160/200	No extrusions
CHO-Seal 1224	Silicone	Ag	0,002	65+/-5	160/200	No extrusions
CHO-Seal 6502	Silicone	Nickel/Al	0,15	65+/-10	125
CHO-Seal 6503	Fluorosilicone	Nickel/Al	0,25	74+/-7	125
CHO-Seal 1285	Silicone	Ag/Al	0,008	65+/-5	160/200
CHO-Seal 1287	Fluorosilicone	Ag/Al	0,012	70+/-5	160/200
CHO-Seal 1298	Fluorosilicone	passivated Ag/Al	0,012	70+/-5	160/200
CHO-Seal 1215	Silicone	Ag/Cu	0,004	65+/-5	125
CHO-Seal S6305	Silicone	Ni/C	0,10	65+/-10	150
CHO-Seal 1350	Silicone	Ag/Glass	0,01	65+/-5	160
CHO-Seal 6307	Epdm	Ni/C	5,00	75+/-7	100	No extrusions
CHO-Seal 6452	Epdm	Ni/C	Na	70+/-10	100	only as extrusion

Shielding (dB)

	100 MHz	500 MHz	2 GHz	10 GHz
CHO-Seal 1221	120	120	120	120
CHO-Seal 1224	120	Na	120	120
CHO-Seal 6502	100	Na	110	85
CHO-Seal 6503	95	110	110	100
CHO-Seal 1285	115	100	105	100
CHO-Seal 1287	110	100	95	90
CHO-Seal 1298	110	100	95	90
CHO-Seal 1215	120	120	120	120
CHO-Seal S6305	100	100	100	100
CHO-Seal 1350	100	100	90	80
CHO-Seal 6307	95	90	85	85
CHO-Seal 6452	75	Na	105	85

EMC shielding and environmental sealing in a single component

In many applications, a seal must not only provide a seal but also perform an electrical function at the same time. This is precisely where electrically conductive elastomer seals demonstrate their strengths. They mechanically seal housing junctions while also supporting the EMC Shielding at critical contact points.

The elastic material conforms to housing contours, tolerances, and contact surfaces. Conductive fillers establish the electrical connection between the components. This creates a solution for transitions, joints, or frame seals that accounts for moisture, dust, and mechanical stresses while simultaneously reducing interference paths.

This is particularly important when assemblies are exposed to fluctuating temperatures, vibrations, or harsh environmental conditions. In such cases, it’s not just the shielding values in dB that matter, but also material durability, galvanic compatibility, and proper compression during installation.

Materials and Fillers: From Silicone to Nickel/Graphite

The choice of material determines whether a seal will function reliably over the long term. Silicone or fluorosilicone are frequently used for electrically conductive elastomers. Depending on the requirements, other Elastomer Bases be relevant, such as EPDM. The conductivity is due to metallic or conductive fillers.

The following parameters are particularly important when selecting materials:

Elastomer base: Silicone, fluorosilicone, or EPDM affect temperature behavior, resistance, and mechanical properties.

Filler: Silver, silver/aluminum, nickel/aluminum, or nickel/graphite affect conductivity, cost, and galvanic compatibility.

Volume resistivity: This value describes the electrical conductivity of the material.

Shore A: Hardness affects compression, installation force, and sealing performance.

Operating temperature: The temperature range must be appropriate for the environment and the operation of the device.

An EMC gasket made of silicone or fluorosilicone should therefore never be selected based on a single value alone. The key factor is the interaction between the material, filler, housing material, and installation conditions. If additional measures for EMC shielding are required in addition to the sealing function, the solution can be tailored to the specific design using conductive foam gaskets, films, conductive coatings, or electrically conductive adhesives.

Select CHO-SEAL Materials Based on Specific Applications

CHO-SEAL comprises various conductive elastomer materials, each with its own properties in terms of conductivity, hardness, temperature resistance, and galvanic compatibility. Therefore, the key factor in making a selection is not so much an additional material table as the question of which requirement is most important for your application.

Relevant factors include the housing material, installation space, desired shielding performance, and the required compression. If you’d like to compare several options, we’ll assist you with the initial technical screening and tailor the material, design, and application to your specific needs.

Overview of Design Types: Extrusion, Molded Part, or O-Ring

Electrically conductive elastomer seals can be manufactured in various designs. The appropriate variant depends primarily on the housing design, the sealing gap, the installation method, and the required quantity.

Extrusions: ideal for linear profiles, sealing strips, and circumferential applications with a defined cross-section.

Stamped and formed parts: suitable for contours, openings, and geometries that must be precisely adapted to a specific installation situation.

Split O-rings and frame gaskets: Suitable for continuous sealing profiles or custom dimensions when standard profiles are not sufficient for the design. For more information, see the splice seals.

This allows the design to be selected appropriately not only based on material, but also on assembly, geometry, and subsequent function.

How to Select the Right Elastomer Seal

The right gasket is not determined by a single material specification. It results from the combination of EMC requirements, mechanical design, and the operating environment. Of particular importance is how much the gasket is compressed and how reliably the contact surfaces remain electrically connected.

These questions will help you narrow down your choices:

What level of shielding is required?

What are the temperature and environmental conditions?

What are the seal gap, tolerances, and available compression?

What material is the housing made of?

Is there galvanic compatibility between the seal, the filler, and the contact surface?

Do you need an extrusion, a stamped part, a molded part, an O-ring, or a frame gasket?

If these points are clarified early on, the selection of materials, samples, and the quote can be tailored much more effectively.

From material selection to the prototype

E.S. Electronic Service not only assists you in selecting products, but also in determining the appropriate technical solution. This includes coordinating the design and materials, evaluating key performance characteristics, and selecting suitable CHO-SEAL variants for your application.

With over 40 years of experience, certified processes in accordance with DIN EN ISO 9001:2015 and DIN EN ISO 14001:2015, and its own on-site warehouse, E.S. Electronic Service is a reliable partner for technical projects involving conductive elastomers.

Get technical advice now

You’re looking for a suitable conductive elastomer seal Would you like to select a product, review a sample, or request a quote? Then contact Please provide us with details about your application, housing geometry, and key technical requirements. We’ll assist you with material selection and the next steps.

Frequently Asked Questions About Elastomer Seals

Elastomer Seals These are elastic seals made of polymer materials. They compensate for tolerances and protect joints from external influences. In their conductive form, they also serve a function in EMC shielding.

What are the different types of elastomer seals?

Elastomer seals are available in a variety of materials and designs. These include silicone, fluorosilicone, and EPDM, as well as extrusions, stamped parts, molded parts, O-rings, and frame seals.

How do electrically conductive elastomer seals work?

Electrically conductive elastomer seals combine an elastic polymer with conductive particles. The polymer provides a seal and remains flexible. The particles provide electrical conductivity and help shield against EMI/RFI interference.

Which design is best suited for enclosures and interfaces?

Extrusions are suitable for profiles. Stamped parts are suitable for defined contours or surfaces. Molded parts are useful for special geometries. Conductive O-rings and frame gaskets are suitable for circumferential housing joints.

Is E.S. Electronic Service a manufacturer of elastomer seals?

E.S. Electronic Service is a Parker Chomerics service center and the technical point of contact for conductive elastomer seals. We provide support with material selection, design, sample requests, and quotes for EMC seals tailored to your application.