Learn the basics of RFI material selection from Specialty Silicone Products (SSP).
Radio frequency interference (RFI) has become an increasingly significant concern in modern electronics, communications, aerospace, defense, automotive, and medical industries. As electronic devices proliferate and operate across a wide range of frequencies, the potential for interference grows.
RFI can disrupt performance, degrade signal integrity, and even pose safety risks in mission-critical systems. To mitigate these problems, engineers rely on RFI shielding materials. Among these, electrically conductive silicone elastomers represent a versatile, durable, and highly effective option—particularly for RFI gaskets and RFI O-rings.
This article explains what an RFI material is. It explores the science behind conductive silicone elastomers, and highlights their advantages, challenges, and applications when used in sealing components such as RFI gaskets and RFI O-rings.
What is an RFI Material?
An RFI material is an engineered substance that’s designed to attenuate or block unwanted electromagnetic energy. It functions by absorbing, reflecting, or conducting radio frequency (RF) signals, preventing RFI from passing through sensitive enclosures.
Important: While the terms RFI and EMI are sometimes used interchangeably, RFI specifically refers to interference in the radio frequency spectrum, typically between 10 kHz and 100 GHz.
To be effective, RFI materials must combine two essential properties:
- Electrical conductivity – to provide a path for electromagnetic energy to be dissipated or redirected.
- Mechanical performance – to maintain sealing, durability, and compliance in demanding environments.
Traditional RFI shielding materials include metals like aluminum or copper. However, metals are heavy, rigid, and prone to corrosion. For applications requiring environmental sealing and flexibility, an RFI material filled with conductive particles is lighter weight, more flexible and – depending on the formulation – resistant to galvanic corrosion.
Electrically Conductive Silicone Elastomers
Silicone elastomers are synthetic polymers based on a backbone of alternating silicon and oxygen atoms, typically combined with methyl or phenyl side groups. This unique structure gives silicones several advantageous properties: flexibility over a wide temperature range, resistance to ultraviolet light and ozone, chemical stability, and biocompatibility.
By themselves, silicone elastomers are excellent mechanical sealants but poor electrical conductors. To make them suitable for RFI shielding, conductive fillers are incorporated into the silicone matrix. These fillers impart electrical conductivity while maintaining the elastomer’s desirable sealing properties.
Common Conductive Fillers for an RFI Material
Several types of conductive fillers are used, depending on the performance requirements and cost considerations for the RFI material.
- Silver or silver-coated particles – Silver is one of the best conductors and offers excellent shielding effectiveness. Silver-coated aluminum or silver-coated glass beads are common choices, providing high conductivity at reduced cost compared to pure silver.
- Nickel-coated graphite – Balances performance and cost, offering good shielding effectiveness and corrosion resistance.
- Carbon-based fillers – Lower-cost option, used when moderate conductivity is sufficient.
- Other metal-coated particles – Such as copper or gold coatings, chosen for specific corrosion resistance or conductivity needs.
The distribution, concentration, and adhesion of these fillers within the silicone matrix determine the final electrical and mechanical properties of the elastomer.
Fabricated Products
RFI gaskets and RFI O-rings made from conductive silicone elastomers play a critical role in RFI shielding. They are designed to be installed in enclosures, housings, or assemblies where they simultaneously provide:
- Environmental sealing – Protecting against dust, moisture, and other contaminants.
- Electromagnetic shielding – Preventing unwanted RF energy from entering or exiting.
RFI Gaskets
Conductive silicone gaskets are manufactured in sheet or extruded profiles and cut or molded into custom shapes. They are used in enclosure doors, seams, and panel interfaces. For example, in military electronics, gaskets seal communications equipment housings to prevent both water ingress and RF leakage.
RFI O-Rings
Conductive O-rings are molded into circular cross-sections and are widely used in connectors, couplings, and cylindrical enclosures. In aerospace and defense applications, O-rings ensure both hermetic sealing and reliable shielding in compact assemblies.
Ask SSP for RFI Materials
SSP makes RFI materials as sheets, rolls, extrusions, and ready-to-mold compounds. We also offer fabricated products like RFI gasket and RFI O-rings. To learn more, contact us.
