Line of Silicone and Fluorosilicone Elastomers Offers Variety of Design OptionsConductive elastomers from UK-based Kemtron Ltd. are fully post cured silicones or fluorosilicones with highly conductive particles that provide low contact resistance between mating surfaces. The various fillers have been chosen to ensure galvanic compatibility between the surfaces. Extruded profiles are available in continuous lengths or can be fabricated to meet specific customer requirements. Conductive elastomers are particularly well suited to use in enclosures where space is limited and high shielding performance is required along with an environmental seal in the form of a single gasket. Care must be taken to match the galvanic properties of the filler as closely as possible to that of the contact metal. A wide range of fillers is offered to meet the needs for electrical conductivity and shielding performance.Learn more about these elastomers at the Kemtron Ltd. website.SMT-Compatible EMI Gaskets Ease PCB DesignGORE-SHEILD® SMT EMI gaskets are electrically conductive EMI gasket building blocks. They are comprised of a conformable, electrically conductive gasket material bonded to a thin solderable metal support layer via an electrically conductive adhesive. The gasket material consists of a polytetrafluoroethylene (PTFE) matrix loaded with highly conductive nickel-based particles. The parts are precision cut to standard lengths and widths and are packaged in standard EIA tape-and-reel format for automated PCB placement using existing surface mount equipment. They are soldered to the PCB via standard reflow processes along with the other board components. By piecing together a series of blocks of identical or varying lengths on the PCB ground trace, a simple and efficient EMI seal can be formed between the PCB and corresponding shield housing. This allows the user to create a low cost, custom EMI gasket at the board level without special tooling or custom installation equipment. These gaskets are well suited to the suppression of unwanted EMI/RFI in both portable and non-portable electronic devices in which inter-cavity shielding is crucial.Look for additional product information on the Gore website.Wire Mesh over Elastomers Available with “Self-Terminating” FeatureThe 1500 Range of Fabric over Foam from Arka Technologies is formed by placing a double layer of wire mesh over a round or rectangular core of elastomer. The mesh layers provide EMI/RFI shielding while the elastomers act as a dust and moisture seal. The standard mesh material is Monel or tin-plated copper clad steel (SnCuFe). These wire mesh-over-elastomer combinations are well suited to use with doors or cabinets or where surfaces may be uneven and low closure forces exist. For the many applications that require “cut-to-length” pieces that must be terminated with adhesive to stop the fraying of the knitted mesh, the company has devised a co-extrusion method of manufacturing silicone knit-overs that results in a “self-terminating” material supplied in continuous lengths for use in a production line. This new self-termination option can be specified by replacing the “0” in the fifth digit of the part number. Elastomers are available in either regular or D-profile versions, and PSA (pressure sensitive adhesive) strips can be added as needed.Look for more product information at the Arka Technologies’ website. Dual EMI Honeycomb Air Filters Deliver Cooling and EMI ShieldingThe dual Honeycomb air filter from Universal Air Filter shields against EMI and is targeted for application in electronics, telecom, and datacom equipment. This filter reduces EMI/RFI noise by using a shielding stainless steel mesh that is bonded to the aluminum frame with a conductive silver/copper adhesive caulk. An EMI shielding gasket is also installed around the frame perimeter, thus assuring dull conductivity between the equipment and frame. The honeycomb structure provides “cells” of Quadrafoam that reflect and absorb EMI noise. Moreover, the honeycomb pattern maintains minimal airflow impedance and provides a “straightening” effect for maximum cooling efficiency.Learn more at the Universal Air Filter website. Mesh Foil Shields Transparent Windows & DisplaysThe 9000 Series from Holland Shielding is stainless steel mesh, fully integrated into the foil. It is protected by a scratch-resistant layer, and it is also available with transparent self- adhesive making it easy to apply to glass, acrylic, and polycarbonate—either by hand or with a laminator. Depending on the mesh quality, it provides shielding between 10 kHz and 30 GHz. The finer the mesh, the more effective it is for high frequencies. The foil can be delivered with a strip of the mesh running longitudinally (flying mesh). Alternatively, a conductive or non-conductive adhesive can be provided along the edges, or a silver bush bar can be placed around the circumference. A termination with a waterproof/EMI shielding gasket is another option. Various options are available for the metallic mesh—including stainless steel, blackened copper, or phosphor bronze.Find more product information on the Holland Shielding website.RF-Absorbent Material Protects Sensitive PCB DesignsThe FFAM Series from API Delevan is made of an RF-absorbent flexible ferrite. The product suppresses EMI that can radiate from active RF components and protects sensitive PCB designs that can be affected by external interference. This material provides effective EMI suppression in the 10 MHz to GHz frequency range with electrical resistance from 106 Ω to 108 Ω. This material is useful in achieving compliance with the most recent FCC and CISPR requirements. The FFAM series comes in four sheet sizes from 100 mm x 100 mm to 400 mm x 400 mm and in six thickness ranges from 0.25 mm to 2.5 mm. The material can be die-cut for gasketing applications and is also available with optional non-conductive UL-recognized adhesive backing.Learn more at the API Delevan website.
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