EMI Shielding

As a premier distributor and fabricator of EMI Shielding products from Chomerics, we offer traditional CHO-Seal^® conductive elastomers.  Call Sealing Devices for applications support and design assistance for designing EMI shielding and thermal management THERM-A-GAP pads and gap fillers.  Cho-Seal, Soft-Shield,Therm-a-Gap,Cho-Therm and Win-Shield are registered trademarks of Parker Chomerics.

Critical features to consider when evaluating EMI Gaskets are:

EMI Shielding Effectiveness

Determining a system overall EMI shielding needs involves understanding the radiated emission spectrum of the equipment, and the specifications the unit must meet. Various EMI gasket types provide different levels of shielding effectiveness across the frequency range of 10 kHz to 20 GHz, such as the Soft-Shield 5000 materials.

Operating Conditions

Many EMI gasket variations provide a 'best fit' for different operating environmental conditions. Exposure to high and low temperatures, wind and rain, salt spray, solvents used in cleaning and plating, and other conditions severely affect the life of an EMI shielding gasket.

Mechanical Requirements

The primary goal of an EMI shielding gasket is to seal an electronic enclosure to prevent transmission of electromagnetic interference. Improper design of the seal or enclosure mating flanges can result in a failure. Several mechanical design issues must be considered for the proper mating of an EMI gasket with the flanges of an electronic enclosure.

Compression-Deflection

EMI gaskets require some amount of compressive force to function properly.As a result of this load, the material will decrease in height (deflect).Many commercial-grade gaskets must deflect 30-40% under low closure forces to properly maintain contact with mating flanges.

Compression Set

Gasket material subjected to compressive forces for an extended time causes 'deflection' to remain when the load is removed. Compression set is an important property in designs where the EMI gasket will be compressed and released regularly while in service in enclosure doors and access panels.

Electrical Stability

EMI gaskets provide conductive pathways that electrically bond system components to a common ground. The gaskets serve as low impedance conductors to ensure the reliability of an enclosure.

Installed Cost

The method of installing an EMI gasket can be a major factor in determining shielding costs. Gaskets can be installed using pressure-sensitive adhesives, fasteners, or epoxies, or by press-fitting into grooves.Some gaskets are molded in place on the enclosure flange or on a plastic spacer frame.

Gasket Mounting Choices

Various EMI gasket mounting techniques offer designers cost-effective choices in materials and assembly. Most Chomerics gaskets attach using easily repairable systems.Applications Engineering can provide full details on EMI gasket mounting. Common systems are shown here with the available shielding products.

Pressure Sensitive Adhesive Quick efficient attachment strip Conductive Elastomers SOFT-SHIELD POLASHEET SPRING-LINE POLASTRIP	Friction fit in a groove Prevents over-deflection of gasket Retaining groove required Conductive Elastomers MESH STRIP POLASTRIP SOFT-SHIELD SPRINGMESH	Adhesive Compounds Conductive of non-conductive spot bonding Conductive Elastomers MESH STRIP

Robotically Dispensed Formed-in-Place Conductive Elastomer   Chomerics’Cho-Form™ automated technology applies high quality conductive elastomer gaskets to metal or plastic housings. Manufacturing options include Chomerics facilities, authorized Application Partners, and turnkey systems.	Friction Fit on Tangs Accommodates thin walls, intricate shapes Conductive Elastomers	Spacer Gaskets Accommodates thin walls, intricate shapes Fully customized, integral conductive elastomer and plastic spacer provide economical EMI shielding and grounding in small enclosures. Locator pins ensure accurate and easy installation, manually or robotically.

Clip-on Gaskets  Require knife edge mounting flange. Conductive Elastomers METALKLIP CLIP-SHIELD SOFT-SHIELD 5000	Rivets/Screws Require integral compression stops Require mounting holes on flange Conductive Elastomers SHIELDMESH SPRING-LINE COMBO STRIP	Frames Extruded aluminum frames and strips add rigidity  Built-in compression stops for rivets and screws. Conductive Elastomers Mesh Strip

Finding conductive o-rings and EMI elastomers, CHO-Seal® Soft-Shield®, Metal EMI Gaskets, Fingerstock and EMI low closure force gasketing for your wireless communications or enclosures from Sealing Devices has never been easier.