Conductive Silicones are often an essential component for hardened boxes and enclosures where environmental sealing and EMI/RFI shielding is required. The typical silicone-based gaskets and seals are impregnated with nickel, silver, copper, aluminum or other conductive particles to give non-conductive silicone their conductivity while providing IP rated environmental sealing that is required in many military electronic applications. These Conductive Silicone materials are also very flexible and can be formed into sheets, extrusions in various profiles, strips, washers and custom molded parts to fit almost any specific requirement, regardless of how unique.
But the one issue with these essential conductive silicone products is that they aren’t designed to withstand a harsh environment where they are regularly exposed to chemicals such as cleaning agents, oils or fuels. Harsh chemicals cause the silicone to break down causing the environmental sealing protection and EMI shielding properties to be lost. These same Silicones can also lose their effectiveness due to galvanic corrosion between the conductive silicone product and the metal enclosure, especially in a shipboard environment. To defend your hardened box or enclosure that is exposed to chemical contamination or heavy salt fog MAJR Products recommends the use of conductive fluorosilicone materials. This is a silicone elastomer which has been fluorinated to stop its breakdown when in contact with harsh chemicals but it maintains needed environmental sealing and EMI/RFI shielding characteristics. “…fluorosilicone rubbers…have excellent resistance to aliphatic hydrocarbons and good resistance to aromatic hydrocarbons, oil and gasoline, animal and vegetable oils, dilute acids and alkalies, and alcohols; and fair resistance to concentrated alkalies.”¹
Like their conductive silicone cousins, conductive particles are added to the fluorosilicone base and the particles that should be used are dependent on your application. The table below shows various options.
When you consider the available number of sheets in various thicknesses or the number of extruded profiles and washers offered, MAJR Products can deliver chemical resistance, environmental sealing and EMI/RFI attenuation in a fluorosilicone component that meets your needs and exceeds your expectations.
Contact us by email or phone (at 877-625-6033) to discuss your unique military or commercial needs. Our engineers will be happy to assist you in choosing the right fluorosilicone material and profile.
¹Encyclopedia of Corrosion Technology, Volume 20 of Corrosion Technology, Edition 2, revised, edited by Phillip A Schweitzer, P.E., CRC Press, 2004, ISBN 0824750446, 9780824750442, pg. 563.