Parylene

From Wikipedia, the free encyclopedia

Parylene

Parylene is the tradename for a variety of polyxylene polymers marketed by several providers, including Para Tech Coating, Inc.[1], Specialty Coating Systems, Inc.[2], and others. Parylene N is a polymer manufactured from di-p-xylylene, a dimer synthesized from p-xylene. Di-p-xylylene, more properly known as [2.2]paracyclophane, is made from p-xylene in several steps involving bromination, amination and elimination. [3]

di-p-xylene

There are a number of derivatives and isomers of parylene, but only a few are used commercially, e.g. Parylene C and Parylene D. This article discusses the unsubstituted molecule, which produces Parylene N. Heating [2.2]paracyclophane in a partial vacuum gives rise to a diradical species[4] [5] which polymerizes when deposited on a surface. Until the "monomer" comes into contact with a surface it is in a gaseous phase and can access the entire exposed surface. It has a variety of uses. In electronics, chemical vapor deposition at low pressure onto circuit boards produces a thin, even conformal polymer coating. Parylene coating has very high electrical resistivity and resists moisture penetration. It is used as a dielectric in certain high-performance capacitors for precision measurement. It has uses in preserving archival paper.

Contents

[edit] Characteristics and advantages

  • Hydrophobic, chemically resistant coating with good barrier for inorganic and organic media, strong acids, caustic solutions, gases and water vapour.
  • Outstanding electrical isolation with high tension strain and low dielectric constant
  • A biostable, biocompatible coating, FDA permission
  • micropore and pin get-free starting from 0.2 µm layer thickness,
  • Thin and transparent coating with high gap freedom of movement, suitably for complex arranged substrates also on edges.
  • Coating without temperature load of the substrates, coating takes place at ambient temperature in the vacuum.
  • Highly corrosion resistant.
  • Completely homogeneous surface.
  • Thermally stable up to 220 °C, mechanically stable from -200 °C to +150 °C.
  • Low mechanical stresses.
  • Resistant to friction.
  • Very low permeability to gases.
  • High electrical impedance.

[edit] Typical applications

  • Dielectric coating (e.g. Cores/coils).
  • Hydrophobic coating (e.g. biomedical hoses).
  • Barrier layers (e.g. for filter, diaphragms, valves).
  • Microwave electronics.
  • Sensors in rough environment.
  • Electronics for space travel and military.
  • Corrosion protection for metallic surfaces.
  • Reinforcement of micro-structures.
  • Abrasion protection.
  • Protection of plastic, rubber, etc. from harmful environmental conditions.
  • Reduction of friction (e.g. For guiding catheters, also acupuncture needles).
  • Dissolving deuterated polyethylene for making nuclear targets.

[edit] External links

[edit] References

  1. ^ Parylene Technology. Para Tech Coating, Inc.. Retrieved on 2007-07-07.
  2. ^ Parylene Knowledge. Specialty Coating Systems, Inc.. Retrieved on 2007-11-25.
  3. ^ H. E. Winberg and F. S. Fawcett (1973). "Tricyclo[8.2.2.24,7hexadeca-4,6,10,12,13,15-hexaene]". Org. Synth.. 
  4. ^ H. J. Reich, D. J. Cram (1969). "Macro rings. XXXVI. Ring expansion, racemization, and isomer interconversions in the [2.2]paracyclophane system through a diradical intermediate". Journal of the American Chemical SocietyEdition 91 (13): 3517–3526. doi:10.1021/ja01041a016. 
  5. ^ *P. Kramer, A. K. Sharma, E. E. Hennecke, H. Yasuda (2003). "Polymerization of para-xylylene derivatives (parylene polymerization). I. Deposition kinetics for parylene N and parylene C". Journal of Polymer Science: Polymer Chemistry Edition 22 (2): 475–491. doi:10.1002/pol.1984.170220218. 
 This article about polymer science is a stub. You can help Wikipedia by expanding it.