PBT plastic protects to 5VA flammability rating
Shielding in automotive applications is provided by the Premier PBT-250FR polybutylene terephthalate (PBT) plastic from Chomerics Europe, a division of Parker Hannifin.
It provides EMI shielding as a single pellet, electrically conductive, flame retardant material and protects where there is potential for fuel exposure or issues surrounding automotive fluid compatibility.
The 2.5mm thick material has been designated 5VA, the highest flammability rating from UL 94, the Standard for Safety of Flammability of Plastic Materials for Parts in Devices and Appliances. This level of flame retardant performance means it is particularly suitable for when the application involves highly flammable fluids. A 5VA rating means burning stops inside 60 seconds on a vertical specimen without dripping (and without creating a hole in the specimen). For a thinner EMI housing, Premier PBT-250FR carries a UL 94 rating of V-0 at 1.5mm thick.
Premier PBT-250FR values extend from 40 to 45dB attenuation at 30 to 1,500MHz, up to 80 to 85dB at 20,000 to 40,000MHz, ensuring the suitability of this semi-crystalline material in almost all automotive fuel/fluid-based applications, says Chromerics. There is also chemical resistance to substances such petroleum, motor oil, brake fluid and anti-freeze.
The material is cost-effective, continues Chromerics as PBT products use continuous stainless steel fibre as the filler content instead of nickel carbon plated fibre, making Premier PB-250FR around 65 per cent less expensive than Premier PC-ABS nickel-plated grades.
Chromerics believes that Premier PB-250FR is the only single pellet material of its type on the market. The resin system eliminates the mixing required with traditional electrically conductive plastic pellets, which produces a uniformity of conductive filler dispersion for consistent electrical properties and mechanical performance.
The material can be run in any injection moulding machine and its easier processing capability allows for smaller barrel capacities. Typical reductions in injection pressure of 30 to 40 per cent translate into smaller press tonnage requirements, notes Chromerics. The use of a single pellet material also eliminates any risk of improperly processed fibre pellets – which can be found in multi-pellet (cube blend) products – leading to agglomerates.
Premier PBT-250FR is manufactured by Parker Chomerics in the USA, and is available immediately.
