Elastomers with conductive fillers
In addition to EMC contact finger strips, electrically conductive elastomer gaskets are another important group of shielding material. They are made from an elastomer binder (silicone or fluor silicone) with a conductive filler. Depending on the technical requirements, the best performing fillers are silver-coated copper, aluminium or glass balls. Pure silver is also available.
A filler with nickel-coated graphite is a good choice regarding the price-performance ratio; the most economical option is carbon-loaded silicone. Elastomer gaskets with conductive fillers have very good attenuation properties between 50 and 120 dB, depending on the product and wavelength und act as seals against dust and water. Especially the duo-seal option can achieve high IP class levels.
The gaskets are available as extruded sections, printed or moulded shapes. Depending on size and quantity, rings can be moulded or made as jointed o-rings from suitable profiles. O-profiles can be made with very small diameters and are therefore perfect for enclosures with thin walls.
Conductive Connector Gaskets
Conductive connector gaskets are stamped according to the customer’s drawing from a conductive fabric bonded over a low-density foam core. The core material is either urethane or neoprene, the conductive fabric Ni/Cu or Ni/Cu + Carbon and provides a good EMI shielding and protection against air, light and dust. Optional, these gaskets can be supplied with adhesive backing.
Conductive Silicone Gaskets
These are very soft gaskets with good shielding properties. The core material is either silicone foam, silicone tube or solid silicone O-profile. The conductive coating is made from silvered copper particles. Due to the coating, the surface of this gasket is rough and will not reach the same properties for environmental shielding as an elastomer gasket with electrically conductive filler.
Conductive Silicone Connector Gaskets
Standard conductive o-ring connector gaskets for MIL standard connectors are manufactured by moulding. This technique offers low tooling costs, shorter lead times and compatible tolerances. A cost-effective alternative, especially for bigger or special dimensions, is an extruded jointed o-ring.
Miniature conductive Sub ´D`connector gaskets and other small flat gaskets can be manufactured by the pure print method. They are printed to the correct form and design without any punching. The material wastage is minimal. Typical thickness is 0.35 mm to 0.50 mm.
Special installation "Duo Seal"
In critical installations with the extra requirements for an environmental and an EMC shielded mounting, achievement can easily be reached with the Duo-Seal products.
This seal is made of two different materials with a vulcanized connecting seam. The environmental seal is made of non-conductive silicone or fluorsilicone, that protects the internal EMC seal from contaminants and humidity from the outside and prevents galvanic corrosion.
The conductive part of the Duo-Seal can be filled with a variety of materials, eg., silver/aluminum, nickel/graphite, etc.