New Low-Outgassing EMI Silicone Withstands Extreme Cold


Specialty Silicone Products (SSP) is announcing a new EMI/RFI silicone, SSP502-55LT, that meets ASTM E595 low outgassing test requirements and withstands temperatures as low as -70°C. Applications for this shielding elastomer include the high-vacuum, low-temperature environment of outer space, where released gases from EMI gaskets can condense upon and cloud sensitive optics.

SSP502-55LT is a 55-durometer, nickel-graphite-filled silicone that joins a growing family of low-outgassing compounds from SSP, including offsets to Parker Chomerics CHO-SEAL® materials and replacements for discontinued GORE® EMI gasketing. SSP’s new material withstands colder temperatures than its offsets to GORE GS2100 and GORE GS5200, both of which are also medium-durometer, nickel-graphite compounds.

ASTM E595 Outgas Tested

In the absence of atmospheric pressure, gases trapped in a porous material are released. ASTM E595 is a standard test method for determining the total mass loss (TML) and collected volatile condensable materials (CVCM) of a specimen in a vacuum. ASTM E595 testing indicates that SSP-502-55LT has a TML of 0.15% and a CVCM of 0.05%. Both values are within NASA’s low outgassing limits.

TR-10 Low Temperature Tested

The retraction rate of an elastomer is related to its low-temperature flexibility. If an EMI gasket becomes rigid at extremely cold temperatures (such as in space), seal failure can occur. ASTM D1329 defines a test method, TR-10, for determining the temperature at which a specimen retracts by 10% of its elongated length. SSP-502-55LT has a TR-10 of  -70°C.

EMI Shielding Effectiveness

The nickel-coated graphite particles in SSP-502-55LT provide silver-like electrical conductivity and EMI shielding. SSP502-55LT has an electric field (E-Field) shielding effectiveness of greater than 113 dB for the 20 MHz to 10 GHz frequency band. Its volume resistivity (VR), an indirect measurement of EMI shielding effectiveness, is 0.01 oh-cm.    

Rolls, Sheets, and Ready-to-Mold Compounds

SSP manufactures and tests SSP502-55LT at its Ballston Spa, New York (USA) facility and offers a Certificate of Analysis (COA) for each batch of material that we make. SSP offers low minimum order quantities and attractive lead times, and buyers can order SSP502-55LT as continuous rolls, fully-cured sheets, or ready-to-mold compounds.

EMI Gaskets for Low Outgassing, Low-Temperature Environments

In addition to ready-to-fabricate materials, SSP offers finished gaskets made from SSP502-55LT. On-site flash cutting and die cutting are used for flat-gasket fabrication, and SSP’s toolroom is equipped with CNC machines and staffed by machinists. In addition to dies, jigs, and fixtures, SSP cuts the molds for the compression-molded EMI gaskets that we make. Contact us to learn more or request a quote.      


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