Specialty Silicone Products (SSP) now offers a 60-durometer, nickel-graphite shielding silicone that meets the flammability requirements of UL 94 V-0, a flame-testing standard from Underwriters Laboratories (UL). Flame-retardant SSP-502-60-V0 is supplied as a ready-to-mold compound, fully-cured conductive sheet stock, or as continuous rolls. This particle-filled silicone supports gasket fabrication through a variety of manufacturing methods and provides environmental sealing and electrical conductivity.
Why UL 94 V-0 Compliance Matters
Underwriters Laboratories is an independent organization that publishes product safety standards along with well-defined testing protocols. UL compliance is voluntary, but can provide your company with a competitive advantage in the marketplace. For example, materials that comply with UL 94 can help to address concerns about the spread of fire from electrical overloads, component failure, insulation breakdowns, and loose connections.
For parts used in electronic devices and equipment, UL 94 defines a method for rating the ignition characteristics of polymers. UL 94 is a single standard, but contains different flame ratings for different types of materials, such as solid rubber. There are also different flame ratings depending on the burn specimen’s orientation. For example, UL 94 V-0 applies to specimens that are positioned vertically. Burning time, afterglow time, and the dripping of burning test specimens are all measured.
SSP’s New Flame-Retardant Shielding Silicone
SSP-502-60-V0 is a 60-durometer silicone that meets the requirements of UL 94 V-0 and provides effective EMI shielding. In electrical devices and equipment, electromagnetic interference (EMI) can cause problems ranging from the temporary disruption of circuits to system failure. By filling a silicone elastomer with metal or metal-coated particles, a compound can combine EMI shielding with environmental sealing. Nickel-coated graphite particles are a good choice because they balance cost with performance.
With SSP 502-60-V0, shielding effectiveness in the 20 MHz to 10 GHz range (E-field) can vary by form factor. For example, SSP’s compression-molded sheets and ready-to-mold compounds have a typical shielding effectiveness of > 113 dB. Continuous rolls have a typical shielding effectiveness of > 100 dB. With continuous rolls, however, material usage can be maximized in gasket fabrication processes such as die cutting and water jet cutting.
