Conformity Magazine - December 2008 - (Page 39)

Table 6 displays the surface resistivity and shielding effectiveness of several conductive coating systems, 30 MHz to 10 GHz. It shows that plating onto all surfaces provides the best shielding effectiveness over the frequency range. Plating on Plastics Applications Shielded Connectors Connector designs in today’s electronic equipment face the competing demand for a smaller form factor, lighter weight, improved mechanical performance, increasing need for EMI shielding, and lower cost. Metal shells used to shield connectors add weight, cost and space. Plated plastic connectors are being used to meet the EMI/RFI shielding requirements, thereby reducing weight and space requirements. Nickel thickness can be varied between 50 and 600 micro-inches (1.25-15.0 µm) to meet mechanical and environmental requirements. Medical Electronic Devices Shielding medical electronic devices present significant design challenges due to the pervasiveness of electronic equipment in the hospital. Autocatalytic selective plating and conductive paint are applied onto many medical electronic device enclosures to provide EMI shielding. Military Electronic Equipment The modern day battlefield is noisy, and military electronic systems need to be shielded against EMI/RFI noise. The move to rapid force deployment drives the need for lightweight mobile electronic systems, and the use of plastics has made significant inroads into the electronic battlefield. Since plastics do not shield against EMI/RFI, they are usually shielded, often with thick electroplated coatings to protect against the wide EMI/RFI frequency range that may be encountered in the field. The plated plastic components can then be coated with mil-spec finishes, including latest generation water borne chemical agent resistant coating (CARC) paints Summary Designing for EMI shielding is best accomplished early in the design cycle before such key issues as plastic resin selection and final part design are finalized. Shielding systems can be tailored to meet the needs of highly cost competitive consumer electronic devices and automotive hardware, as well as critical performance applications in medical devices and military electronics. Jim Skelly is president of Cybershield, and can be reached at jimskelly@cybershieldinc.com. Figure 2: Examples of plated plastic connectors Figure 3: A example of a typical medical device housing FAST Link www.conformity.com/2460 Figure 4: Some examples of military electronic equipment (photo courtesy of DRS Tactical Systems) DeCember 2008 Conformity 39 http://www.conformity.com/2460

Table of Contents Feed for the Digital Edition of Conformity Magazine - December 2008

Conformity Magazine - December 2008 Contents Editor's Note FCC Warns Regulatory Fee Payers About Potential "Phishing" Commission Prowls the Web to Enforce Its Regulations First DTV Rollout Initiated in Wilmington, NC New Standards List Released for the EU's Directive on the Safety of Toys ESD Association Call for Papers ESDA. JEDEC Announce Standards Development Cooperation Commission Releases Data on Local Telephone Competition The Future of ESD Testing ESD Open Forum Emerging Issues in Standards: China RoHS: One Year and Counting Challenges in Testing: Revisiting 10-Meter and 3-Meter Radiated Emission Measurements Design Fundamentals: Meeting the Shielding Challenges of Injection-Molded Plastics Focus On...Microwave Absorbers Buyer's Guide FDA Recalls Automated External Defibrillators FDA Revises Guidance on Medical Device Tracking Guidance Document Safety of Passive Implants Released FDA Offers Guidance on Marketing Diagnostic Ultrasound Systems EU Commission Issues Correction on Machinery Directive Standards Other CPSC Actions in the News Product Reviews IEC Standards Update UL Standards Update Looking Back: Items from Past Issues of Conformity Advertisers

Conformity Magazine - December 2008

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