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Parylene Coating
Parylene conformal coating is suitable for metals, elastomers, electronics, and plastics and is used extensively in the automotive, aerospace, electronics, and medical industries. Parylene coating is an ultra-thin film polymer coating that provides a uniform pin-hole-free barrier coating to all shapes, edges, crevices, and recesses with the same thickness without suffering any of the edge effects of conventional coatings.
Parylene Coating can be applied to various materials like substrates, plastics, metals, elastomers, electronic components, assemblies
Parylene coating is performed in white and clean room facilities with
custom-designed equipment and is derived from proprietary dimers. Parylene
is applied under vacuum by vapor deposition at room temperature.
Stage 1 – SUBLIMATION – the dimer is heated in a partial vacuum to 150° C resulting in
conversion from a solid to a gaseous state. Coating thickness and
uniformity are both dictated by the amount and purity of dimer used. Our
proprietary dimers are 99.6% pure.
Stage 2 – PYROLYSIS – gaseous dimer is heated in a furnace. As the temperature rises the
molecular structure changes and it begins to crack or break down. At over
650° C the dimer is split into monomers.
Stage 3 – POLYMERIZATION – In the deposition chamber, where the coating of the customer-provided
product takes place, the parts to be coated are maintained at room temperature. Still, in its gaseous phase, the monomer is drawn into the chamber and undergoes polymerization. The nanoparticles combine chemically to provide a chainlike or network molecule. At a rate of 1-2 microns per hour, a single clear coating builds up one molecule at a time, encapsulating all exposed surfaces. Controlled coating thicknesses ranging from less than 10 nanometers to 70 microns are achieved in a single operation.
- Monomer flow
is directed tangentially to the chamber load using a proprietary fixture
design to enhance diffusion and coating uniformity while minimizing raw
material consumption. - Variable Aperture Plates are below the fixtured parts, and these plates are pre-adjusted on the
basis of the volume and geometry of each chamber load to achieve a uniform
and effective deposition.
Parylene Conformal Coating - Industries
Parylene Conformal Coatings - Applications
- Catheters
- Mandrels
- Sensors
- Ultrasound transducers
- Guide wires
- Needles
- Epidural probes
- Elastomer components such as Silicone and latex components
Solutions
- For medical devices requiring biomedical compatibility and barrier protection against biofluids, moisture and chemicals.
- Also acts as a dry film lubricant with a coefficient of friction measurement that approaches that of TEFLON®.
- Parylene type N is typically used in applications requiring this type of releasability or dry film lubricant.
- Circuit board
Solutions
- Even and consistent barrier coating which does not pull away from the edges or exhibit meniscus forces.
- Excellent dielectric strength.
- Resistant to humidity and practically insoluble in all known organic and inorganic solvents including acid and alkali.
- Magnets
- Wire wound ferrite cores
- Powdered ferrite cores
Solutions
- Elimination of abrasion damage to the wire along with uniform coating thickness
- Maximum winding window.
- Low water vapour transmission provides excellent corrosion protection
- Eliminates magnetostrictive or permeability problems
- Elastomer components
- Rubber keyboard and controls
Solutions
- Conforms to surface features including internal dimensions of holes.
- Strong surface adhesion and elasticity.
- Removes elastomer tack and protect against dirt, oils, petrochemicals and solvents.
- Protects printed legends from wear.
Parylene Conformal Coatings - Benefits & Added Values
Benefits
- Complete Surface Conformability
- Pinhole and Stress Free Application
- Dielectric and Moisture Barrier
- Ruggedized Purpose
- Superior Electrical Insulation
- Low Dielectric Constant
- Biocompatibility and Bio-Stability (can be sterilized)
- Optical Clarity
- Zero Outgassing of Volatile Chemicals
Added Values
- The Parylene coating process does not include a liquid phase, thus the coating will not pool in low areas, bridge across substrate features, or exhibit liquid properties such as meniscus or capillary action.
- Parylene film is a pure, polycrystalline, and amorphous linear polymer distinguished by superior dielectric, gas barrier, and mechanical properties, giving it the ability to meet coating requirements in very thin layers.
- Low static and dynamic coefficients of friction, giving it dry film lubricity that can be valuable for some applications.
- The room-temperature deposition process makes Parylene coating suitable for many substrates, including ferrites, rubbers, silicone elastomers, paper, resins, plastics, silicon, metals, and even granular material
- Since Parylene coating is highly effective in very thin coating applications, delicate substrates such as electronic sensors or diaphragms can be protected without significant mechanical or loading effects.
Parylene Coating - Dimer Supplier
Parylene raw materials are called dimers. CWST offers IPC-CC-830 and USP Class VI approved Parylene dimers. These are the key raw materials used in the Parylene coating process. The most common types of commercial parylene raw material or dimers are Dimer C and Dimer N.
Parylene Conformal Coating Methods
Parts such as printed circuit boards, medical components, and other assemblies that require selective Parylene coating coverage must be masked before coating to restrict exposure to the polymerizing gas in the vacuum chamber. Parts are then placed in fixtures that hold them in place during the parylene coating cycle and provide the optimum combination of chamber loading and exposure to the monomer gas.
Unfixtured, high quantity, and uniform components that do not require masking can be placed in a rotating cylinder sealed within the coating system vacuum chamber. The components are kept in motion throughout the deposition cycle, allowing the polymerizing gas to reach and coat all surfaces evenly. Multiple component types can be treated simultaneously in this manner without sorting or isolation.
Parylene Coating Properties & Variants
Parylene Coating FAQs
Parylene is green chemistry, it produces no cut forces, no thermal stresses, or leachable ingredients
The unique Parylene polymer series was isolated by a research chemist in the late 1940s at the University of Manchester in England. Union Carbide Corporation scientist William Gorham later developed a deposition process to apply the film, and Union Carbide commercialized the material and process. CWST Para Tech Coating, purchased licensing for this coating process in 1968, and subsequently developed and patented several important enhancements that optimize performance, consistency and reliability of Parylene vacuum deposition coating.
Curtiss-Wright Surface Technologies can provide spare parts, critical components, and materials for the operation of Parylene coating machines. Our expert team can provide technical support to trouble shoot and repair coating equipment.
