Electrically conductive O-rings and elastomer profiles

Electrically conductive O-rings and elastomer profiles are used to create reliable EMC and EMI seals in electronic enclosures, appliances and industrial systems. By combining the flexibility of the elastomer with electrically conductive fillers, the seal can provide both electromagnetic shielding and a seal against the surrounding environment.

We offer solutions for applications where the choice of material, profile geometry and electrical contact need to be tailored to the design requirements. We can help you choose the right type of conductive gasket for your application.

Conductive O-rings for EMC and EMI sealing

An electrically conductive O-ring is an elastomeric seal containing conductive particles. When the O-ring is compressed between two contact surfaces, it can form an electrical connection across the joint, thereby helping to limit electromagnetic interference.

Guide O-rings are often used in circular grooves, connections and enclosure components where a traditional O-ring geometry is suitable. They can be an alternative when the design needs to combine EMI shielding with a defined sealing function.

The choice of material, dimensions and compression affects both the electrical and mechanical performance. The gasket should therefore be selected on the basis of the specific design’s requirements regarding shielding, operating environment and service life.

Extruded elastomer profiles

Extruded elastomer profiles can be used as EMI gaskets made from silicone or other suitable elastomer materials. The profiles are manufactured in various cross-sections and can be adapted for use in, for example, enclosure joints, openings and other contact surfaces.

A profile can be selected to suit an existing track or a specific mounting solution. When selecting dimensions, it is important to take into account the design of the contact surface, the available compression and how the gasket is to be fitted.

For applications with specific geometric requirements, bespoke profiles may be suitable. Swelex can help to assess suitable options based on drawings and technical specifications.

Materials and conductive fillers

Electrically conductive elastomers consist of a base material and a conductive filler. This combination affects, amongst other things, electrical conductivity, mechanical properties and resistance to various environments.

Material or filling Typical characteristics Things to bear in mind
Silicone A flexible elastomeric material with good performance across a wide temperature range. The choice of quality depends on temperature, compression and environmental requirements.
Fluorosilicone An elastomer with improved resistance to certain fuels and oils compared with standard silicone. Suitability must be assessed in relation to the specific media and operating conditions.
Silver-based fillings Can provide high electrical conductivity. The choice is influenced by shielding requirements, cost and compatibility with contact surfaces.
Nickel- or carbon-based fillings Alternative conductive fillings to meet various technical and economic requirements. Electrical properties and corrosion behaviour vary between grades.


The table provides a general overview of materials. The exact properties, available combinations and technical data must be verified for the selected product.

Galvanic corrosion and IP rating

When selecting an electrically conductive seal, it is important to take galvanic corrosion into account. If the seal’s conductive filling and the metal of the housing have different electrochemical properties, there is a risk of corrosion, particularly in the presence of moisture or other electrolytes.

This risk can be reduced by carefully selecting the filling and casing materials, applying a suitable surface treatment, and using a design that limits moisture ingress. The choice of materials should always be assessed on the basis of the actual environment in which the product will be used.

The IP rating describes the enclosure’s protection against the ingress of solid objects and water. A conductive elastomer gasket can contribute to the enclosure’s seal, but a specific IP rating cannot be guaranteed solely by the choice of material. The result also depends on factors such as groove geometry, compression, contact surfaces and the design of the finished enclosure. Where a specific IP rating is required, the complete design should be verified through appropriate testing.

 

Applications for guide O-rings and extruded elastomer profiles

Sealing O-rings and extruded elastomer profiles are used in many types of electronic and industrial designs, for example:

Electronic enclosures: Sealing of joints and openings where electromagnetic shielding is required.

Telecommunications equipment: EMI sealing in enclosures and equipment subject to interference control requirements.

Industrial electronics: Gaskets for equipment and systems where electrical contact across enclosure joints is important.

Measurement and control equipment: Customised seals for sensitive electronic components.

Customised designs: Profiles and O-rings selected on the basis of specific dimensions, materials and environmental requirements.

Frequently Asked Questions: Electrically Conductive O-Rings (FAQ)

  • What is an electrically conductive O-ring?

  • It is an O-ring made from an elastomer material containing electrically conductive fillers. It can be used to establish electrical contact between two surfaces and contribute to EMC and EMI shielding, whilst also acting as a seal.

  • Silicone or fluorosilicone – which should I choose?

  • Silicone is a common choice for many electronic applications. Fluorosilicone may be suitable where increased resistance to certain fuels and oils is required. The final choice should be based on temperature, chemical exposure, mechanical requirements and the desired electrical performance.

  • How can I prevent galvanic corrosion between the gasket and the casing?

  • Select a suitable combination of conductive filling and housing material, taking into account the surface finish and the environment in which the product is to be used. In damp or corrosive environments, it is particularly important to assess the material combination and the design’s sealing.

  • Can you manufacture bespoke profiles?

  • Please contact Swelex with your drawings, required dimensions and technical specifications, and we will help you explore suitable options for bespoke elastomer profiles.

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