Parylene

As a group Parylene inert, hydrophobic, optically transparent polymeric coating materials are referred with a wide range of industrial applications. In addition to the hydrocarbon poly -p -xylylene ( parylene N as often referred to ) can also halogenated polymers are used.

The coating is applied in a vacuum by the condensation of the gas phase as a pore- free and transparent polymeric film to the substrate. Here, each substrate material such as metal, glass, paper, paint, plastic, ceramics, ferrite and silicones with parylene is practically coated. Due to the gaseous deposition also areas and structures can be obtained and coated, which can not be coated with a liquid-based processes, such as, for example, sharp edges and points or narrow and deep gaps. In one operation, coating thicknesses can be applied from 0.1 to 50 microns.

Properties

Parylene are hydrophobic, chemically resistant plastics with good barrier effect against inorganic and organic media, strong alkalis, acids, gases and water vapor. A thin, transparent coating with a high crack penetration they are suitable for complex shaped substrates. It forms - as Parylene has no liquid phase - no edge marks. Parylene have good dielectric properties with a high withstand voltage and a low dielectric constant. As a bio-stable and biocompatible coating parylene have an FDA Master File. As of 0.6 micron thickness they are micro- pores and pinholes. The coating takes place without thermal stress of the substrates at room temperature in vacuo. This method offers a very high corrosion protection and a uniform layer formation, which - depending on the parylene - type - up to 350 ° C ( Parylene HT) is thermally stable, mechanically stable and produces low mechanical stresses, caused (Shore R80 - R120, depending on the type ) is abrasion resistant and in which no outgassing occurs. This surface can be activated by low-pressure plasma, or other adhesion promoters.

Production

Parylene can be formed by chemical vapor deposition. The starting material is p- xylene, ( 1) (or halogenated derivatives thereof ). This is vaporized and passed through a high temperature zone. Here, a reactive [2,2 ] - paracyclophane ( 2), which decomposes to give 1,4 - Chinondimethan ( 3). The Chinondimethan polymerizes on surfaces immediately to the chain-type poly -p -xylylene (4).

Typical Applications

Typical applications for Parylene are:

  • Conformal coating of electronic components for harsh environment (meets " MIL-I- 46058C, Type XY" (this standard was set on 30 November 1998 "do not use for new designs " on ) )
  • Hydrophobic coating (e.g. biomedical tubes )
  • Barrier layers (for example, filters, membranes, valves)
  • Microwave electronics
  • Sensors in harsh environments
  • Electronics for aerospace and military ( Shelf Life Extension )
  • Corrosion protection for metal surfaces
  • Reinforcement of microstructures
  • Abrasion
  • Protection of plastic, rubber, etc. from harmful environmental influences
  • Reduction of friction (eg, guide wires for catheters )
  • Biocompatible coatings for medical implants (eg transponders for animal registration)
Hydrophobe List of coating techniques Ferrite (magnet)
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