Gary Evans, CEO of Powell Electronics Europe gives his insight into shielding technology for RFI
While EMC should always be considered in the earlier stages of design, quite often it is left as a last-minute fix. To address this issue, Powell Electronics, the supplier of connectors and more for high-rel applications including defence, aerospace and industrial, recently signed a Pan-European franchise distribution agreement with P&P Technology, a European manufacturer of radio frequency and electromagnetic interference (RF & EMI) shielding products. P & P has products to fit most applications and can provide technical design support to assist in establishing the most suitable method of fulfilling customer requirements.
Included within P&P’s range are EMC gaskets and O-rings to fit all standard connector profiles, ‘honeycomb’ EMI shielded vents and a wide range of conductive elastomers, including conductive particles in silicone and oriented wires in silicone, both designed to provide high EMI screening performance and excellent environmental protection.
Connector gaskets
P & P’s connector gaskets are available in a wide range of materials, including various conductive silicones and plain environmental materials. P & P can assist in the choice of material to ensure the chosen one achieves all of the design requirements.
Gaskets are cut using a precision automated CNC cutter, which can produce intricate and precision parts from just a technical drawing. Many of the gaskets are industry standard designs and are available according to MIL-C-81511, MIL-C-5015, MIL-C-38999 and MIL-C-26482 in industry-standard configurations including BN, BNC, D, WG, WR, IEC, UG, AN, however bespoke parts can be produced with a short turn-around time.
Honeycomb vents
P & P have a strong market position in the manufacture of EMI attenuated vents. They can offer products ranging from a very basic single layer aluminium vent to a fully bespoke vent assembly including dust filters, gasket and kickplates.
Vents are available in aluminium and can include 2 layers of honeycomb to increase performance. However, P & P also have high performance vents manufactured from Brass, Steel and Stainless Steel. Each material has its specific properties and can be chosen to increase performance and/or environmental resilience.
Honeycomb ventilation panels are usually supplied with gaskets in a ready-to-mount form. They can be fitted with protective ‘kick-plates’ to protect the honeycomb material from accidental damage. Where they may be exposed to the elements, the vents can be fitted with ‘slant’ honeycomb which provides a downward facing aperture, preventing the ingress of rainwater. This has the added benefit of directional airfl¬ow and increased attenuation due to the higher aspect-ratio of the cell structure.
Oriented wires in silicone
Oriented wires in silicone rubber combine excellent environmental protection with a high level of shielding effectiveness. Gaskets using this technology incorporate a matrix of vertically oriented wires which pierce both flat faces of the elastomer and provide around 100 contact points per square centimetre.
Available materials include solid silicone and sponge silicone variants as well as fluoro-silicone (petro-chemical resistant), flame-retardant sponge silicone and flame-retardant solid silicone. These are produced in a block and then cut into sheets. Once a sheet is cut, P & P can supply the material in strips or can then cut the sheets into bespoke gasket profiles to meet the customer’s specifications.
The benefits of oriented wires in silicone is that this approach offers the same great performance as more traditional conductive particle loaded materials. However, it is typically available on a shorter lead-time and at lower cost.
Other available approaches
In addition to their conductive elastomers and screened ventilation panels. P & P Technology offer an extensive range of products including shielding windows, knitted wire meshes and gaskets, form in place gaskets, conductive fabric over foam, conductive contact finger stock, conductive adhesives, foil tape, cable glands and a wide range of thermal materials. Such a wide range helps P & P provide a one stop approach to fulfilling any customer’s requirements.