Vacuum Design Constraints and Considerations - Owens Design

Low Outgassing Plastics
• PolyBenzImidazole
– Celazole® is the highest temperature-capable plastic available. However, it is very brittle (almost ceramic-like) and quite
difficult to machine. That said, is it frequently used for bushings, bearings, rollers, and spacers in extreme environments.
Polyimide
– DuPont Vespel® SP-1 is one of the most-used high-temperature plastic materials used in applications where high-purity
and electrical properties are needed. Vespel is frequently used in ultra-clean semiconductor and chemical applications. It
is also one of the most expensive materials sold, but is flight-approved for NASA, USAF and other aerospace agencies.
– Duratron® XP is the first real alternative to Vespel ... it was developed specifically to replace Vespel in extreme
applications at a slightly lower price. It contains less than 1% metallic impurities as measured using the ICP-MS test
standard. Duratron XP is ideal for use in high-energy gas plasma etch and strip processes.
• PolyAmide-Imide
– Unfilled Torlon® 4203 has high dielectric properties and low thermal expansion, and is much less expensive than some
advanced polymers. Torlon 4203 is typically used for insulators, spacers, and mechanical parts up to 520°F.
– Torlon 5530 (30% glass-filled) is typically used for applications where dimensional stability over a wide temperature
range is needed, as with temperature test sockets, nests, and fixtures. : Torlon's moisture absorption is a bit high, so
critical dimensional stability can be an issue.
• Semitron® ESd 500HR (filled PTFE)
Semitron® ESd 500HR is antistatic/conductive PTFE. This material is relatively clean, readily machinable,
dissipates static electricity reliably ... as a result it is used in test handling equipment, fixtures, and other
applications where static generation may cause failures and/or errors in production environments. PTFE
has good mechanical properties up to approximately 500°F.
• Neoflon® PCTFE (PolyChloroTetraFluoroEthylene)
PCTFE exhibits high chemical resistance, low and high temperature capability, resistance to most
chemicals (including strong acids and bases), low friction, electrical and thermal insulation, and
"slipperiness".