Parker unveils low-durometer EMI shielding gasket

Above: Softer CHO-SEAL 1299 from Parker Chomerics delivers excellent shielding effectiveness and corrosion resistance.
Courtesy Parker Chomerics 

CHO-SEAL 1299 offers a lower hardness (only 45 Shore A typical) than many traditional conductive elastomer gaskets while still providing highly effective shielding and corrosion resistance against aluminium.

CHO-SEAL 1299 is an electrically conductive EMI shielding elastomer gasket consisting of passivated silver-plated aluminium particles in a fluorosilicone binder. The new material offers a higher temperature limit than most conductive fluorosilicones (up to 200°C continuous use) and is resistant to harsh chemicals such as machining coolant, hydraulic fluids, mineral oils and various fuels.

While the legacy CHO-SEAL 1298 is among Chomerics’ most trusted products, the material needs more force to compress than certain applications can provide. Parker developed CHO-SEAL 1299 to provide customers with the same performance they trust in a softer form.

At only 45 Shore A hardness (35% softer than CHO-SEAL 1298), the low compression force of CHO-SEAL 1299 makes it ideal for EMI shielding applications that include military communication modules, unmanned aerial vehicles (UAVs), naval and shipboard electronics, portable electronics and robotics equipment. 

Providing protection against the ingress of dust, moisture and more, the new RoHS-compliant material is groundbreaking for the many electronic device applications that require design flexibility without compromising EMI shielding effectiveness. 

One common use case is connector interface seals. In smaller connectors, it can be especially difficult to compress a conductive elastomer material by even small amounts because of the high force necessary. Access to a softer material will benefit customers who have encountered a similar challenge. 

As an electrically conductive fluorosilicone elastomer, CHO-SEAL 1299 provides great EMI shielding across a broad frequency spectrum. For example, according to the MIL-DTL-83528 test method (para 4.5.12), the new EMI gasket material delivers a minimum shielding effectiveness of: 128 dB at 100 MHz (E field), 102 dB at 500 MHz (E field), 110 at 2 GHz (plane wave), 122 dB at 10 GHz (plane wave) and 94 dB at 18 GHz (plane wave).

While the legacy version offers an elongation of 60%, CHO-SEAL 1299 can provide 100% according to the ASTM D412 test method. Superior elongation supports greater flexibility and ductility, permitting the new material to conform to irregular surfaces and resist deformation without fracturing. This capability is vital for maintaining an effective seal and shielding against EMI and makes the gasket easier to install.



CHO-SEAL 1299 is available in moulded format, including O-rings, D-rings or custom-moulded shapes. Parker Chomerics also provides the new material in sheet format for cut gaskets. Sheet stock can be die-cut using a steel rule, X-Y knife cut or water-jet cut (non-abrasive) to make precision parts in large quantities. If required, sheet stock can be provided with an electrically conductive, pressure-sensitive acrylic adhesive (PSA) to aid the assembly process. In addition, CHO-SEAL 1299 will soon be available in extruded profiles.