Applications – Parylene coating has been commercially available for over 30 years and its properties are use in a wide range of applications.
The Parylene film is chemically inert, no acid or alkaline material will attack it in any significant manner. The FDA has approved the Parylene film for human implantable devices. The Parylene film possesses superior dielectric properties, approaching 8000 volts for 1 mil thickness.
Circuit Boards: Coatings are thin, truly conformal, stress-free and resistant to solvent and fungal attack. Good adhesion minimizes ionic conduction at the coating-substrate interface and strengthens solder joints. Low dielectric constant minimizes loading in high frequency applications.
Hybrid Circuits: Good adhesion to ceramic substrates. Good throwing power enables coating within spaces as narrow as 10μ. Interior of packages may be coated via a 1mm hole – coating strengthens wire-bonds and immobilizes particles of debris such as solder balls.
Components: Ferrite cores and bobbins are coated to reduce friction and abrasion in coil forming and to prevent chipping and dust formation. Coating cast metal magnets gives corrosion protection and electrical insulation. Accelerometers, strain gauges, pressure sensors etc may be coated for electrical insulation and environmental protection.
Rubber and Plastics: In the coating process the monomer is able to penetrate the surface of rubbers and plastics giving very good adhesion. A 2μ coating imparts dry lubricant and wear resistance characteristics to the surface. For example silicone rubber keypads are coated to improve the ‘feel’ of the surface and to protect the printing and ‘O’-rings are coated to reduce friction in, for example, syringes. A thicker coating improves chemical and solvent resistance.
Optics & Instrumentation: The excellent optical and barrier properties of Parylene and the stress-free nature of the coatings find many uses in this field, particularly in protecting moisture-sensitive elements such as potassium bromide windows. Freestanding films of Parylene may be produced by stripping the coating from suitably prepared glass plates and are used to produce windows and other components in instrumentation.
Medical Components: Because Parylene has excellent barrier properties, cannot be hydrolytically degraded in the corrosive biological environment and is capable of penetrating and coating the bore of narrow tubes it has many uses in this field:
The unique application process and the predictable barrier properties and mechanical strength of Parylene coatings have also found other interesting applications: