Clip-On EMI Gaskets

SHIELDING PROBLEM: An electronics enclosure for a cellular base station needed excellent EMI shielding and resistance to outdoor environments. The designers preferred not to use pressure sensitive adhesives to attach the EMI gaskets on the enclosure doors.

DESIGN REQUIREMENTS: • Provide 80 dB shielding effectiveness from 200 MHz to 10 GHz • Provide resistance to heat, humidity, salt fog corrosion, and rain • Provide a solid mechanical attachment of the EMI gasket without the use of PSA’s • Provide cost effective solution and easy gasket installation

THE CHOMERICS SOLUTION: The EMI gasketing solution consisted of a nickel-plated graphite filled silicone, custom designed crosssection, extruded EMI gasket. The gasket was adhesively attached to a composite thermoplastic/metal mechanical clip for attachment to the enclosure flange.
Specifically, the design used Chomerics CHO-SEAL S6305 conductive elastomer material. This material was chosen for its excellent EMI shielding and suitability for outdoor gasketing applications. The particular cross section was engineered using Chomerics in-house Finite Element Analysis laboratory. This facility defined the required cross section necessary to ensure adequate environmental and EMI sealing. This design provided for the necessary low impedance electrical connection from the gasket to the enclosure flange via the mechanical clip.

KEY FEATURES:
• Gasket is cut, corner- spliced, and attached to the mechanical clip to allow installation of a single part to the enclosure doors
• Single gasket design obviates need for separate EMI and environmental seals
• Custom, extruded shape accommodates the pre- specified door design as well as latch and hinge designs.
• The use of a mechanical clip ensures solid mechanical attachment of the gasket to the enclo sure.

CONCLUSION: CHO-SEAL, conductive elastomer, clip-on EMI gaskets provide a cost efficient, high performance solution for outdoor enclosures.

For more information, see Chomerics'
CLIP-SHIELD™ Clip-On Conductive Elastomer Gaskets