Originally Published MPMN July/August 2001

Spotlight on EMI/RFI Control

RFI cable filter ferrites

RFI cable filter ferrites are available in 74 different styles, including a full range of cable or bundle sizes up to 1 in. diam. Attenuation is up to 1 GHz. Mounting options include clamp on, adhesive, post mount, and tie wrap. Eclipse Shielding, 21121 Ponderosa, Mission Viejo, CA 92692.

RFI suppressors

Cable-snap bisected ferrite suppressors are available in 48 sizes and styles for round wires or bundles up to 1 in. diam. An internal spring-pressure system assures constant electromagnetic properties even in extreme cable positions. The suppressor attenuates RFI up to 1 GHz while allowing data signals to pass unimpeded. A variety of mounting options are available as standard from stock. FerriShield Inc., 350 Fifth Ave., Ste. 7310, New York, NY 10118-7591.

Shields, foil laminates, gaskets

A full line of EMI/RFI shields, foil laminates, thermal materials, and fabric-over-foam gaskets are designed and fabricated from a variety of materials to meet customer specifications. Working with the latest technology in die-cutters, water-jet cutters, stamping presses, laminating equipment, roll slitters, adhesive and assembly workstations, and forming machines, the company can develop a prototype in the lab and quickly take the project through to final production. Orion Industries Inc., 1 Orion Park Dr., Ayer, MA 01432.

RFI filters

Powerline filters are designed to meet requirements for conducted noise emissions. The manufacturer has recently added to its line of RFI filters with a 10-A power-entry filter for both medical and standard applications. Also available are a line of dc filters up to 700 A and three-phase filters rated from 8 to 600 A, 600 V. Curtis Industries, 2400 S. 43rd St., Milwaukee, WI 53219.

Precision-woven screening

A supplier of precision-woven screening offers a broad range of products suitable for EMI/RFI shielding applications. Materials include copper, stainless steel, carbonized nylon, and others. Various mesh sizes are available to meet required attenuation levels. Custom products are also available. Sefar America Inc., 111 Calumet St., Buffalo, NY 14043.

EMI/RFI/ESD coating services

A company provides coating services for EMI/RFI/ESD shielding. Physical vapor deposition (vacuum metallization) can be used to apply either a functional or decorative thin-film coating of 99.8% pure aluminum to most plastic injection-molded, extruded, or thermoformed enclosures. The company can also provide spray coating of conductive nickel-, copper-, or silver-filled water-based paints. Summit Coating Technologies LLC, 25 N. 43rd Ave., Phoenix, AZ 85009-4607.

RFI shielding

Used where a concentration of contact force is needed, the spherically radiused contact areas of low-contact resistance RFI shielding assure a strong electrical bond to the mating surface. The units are especially suited for vibrating or mechanical-shock environments. A variety of sizes for various gaps and mounting surfaces are available in a surface-mount adhesive tape version or a clip-on configuration. Omega Shielding Products, 9 Emery Ave., Randolph, NJ 07869.

Shielding systems

Two shielding systems, a screen room and a solid-cell enclosure, are designed to contain disruptive radiating signals from high-emission devices. The systems also guard against high-voltage sources and electromagnetic pulses. Applications include EMC product-compliance testing, instrumentation repair, and production-line testing. Lindgren RF Enclosures Inc., 400 High Grove Blvd., Glendale Heights, IL 60139.

EMI gaskets

Gaskets can be placed along the ground trace on a PCB to provide EMI shielding. As an RF grounding pad or interconnect, the Gore-Shield SMT EMI gaskets conduct currents of a primary RF signal much the same way a connector conducts RF currents from a PCB to a coaxial cable. Applications best suited for this use are found in situations where a RF signal needs to be sent from one PCB to another and the two boards are sandwiched together. W. L. Gore & Associates Inc., 750 Otts Chapel Rd., Newark, DE 19714.

Optical-quality fine-wire mesh

Sheets and custom sizes of fine-wire mesh with a conductive plating are available for EMI/RFI shielding of electronic displays and enclosures. EMIgard optical-quality meshes are produced in 304 stainless steel, copper, and custom alloys. Meshes come with 50 to 250 openings per inch in standard sheet sizes of 22 x 28 in. or precut to customer-specified sizes. In the company's manufacturing process, the mesh wires are encapsulated in a conductive silver-and-black alloy plating to maximize transmittance, shielding, and environmental durability. Dontech Inc., 700 Airport Blvd., Doylestown, PA 18901.

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