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EMC screening options

Joe Bush, Editor

11/12/2011

Tags: Enclosures

Topics: Enclosures

Vero Technologies are offering a range of lightweight standard plastic enclosures that are available in different styles and sizes to help reduce time and cost to market for new projects. Complex shapes and features can also be incorporated into the design and the range can also be modified to accept displays, switches, connectors and other hardware.

However, if radiation emitted by the housed electronics or their susceptibility to external fields is a potential problem, moulded enclosures offer no inherent attenuation to the passage of electromagnetic fields.

To provide screening, Vero Technologies offers three alternative internal coatings that provide varying levels of attenuation to suit different applications. For less demanding commercial applications, the lowest cost 50 micron nickel coating provides attenuation of 50dB at 1GHz. The default coating is a 10 or 20 micron silver coated copper particle coating, which typically attenuates by 78dB at 10GHz. The highest attenuation is achieved using a 22.5 micron silver coating, which gives in excess of 80dB at 1.5GHz. For highly specialised applications, other coatings are available.

A tongue and groove structure between the mating halves of an enclosure forms a complex path, improving the attenuation performance. Removable end panels are secured into an interference fit slot or, if fixings are used, a conductive gasket should be fitted to the mating surface. The rear face of plastic panels will have to be conductively coated, or if aluminium panels are used, the front surface will normally be anodised and the rear left with a natural finish or iridised - a RoHS complaint conductive finish.

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