As one of the most widely-used conformal coating types, parylene has a significant reputation. Read on to learn about this coating and the advantages of using it in a variety of environments, projects, and settings.
The term "parylene " refers to a series of polymers based on the hydrocarbon paraxylene. These polymers are unique among conformal coatings--not just for their ability to adapt to a variety of substrate materials and angles, but for their unmatched reliability and durability.
There are three main types of parylene:
Each is used in different environments due to slightly different characteristics; for example, parylene C and D are similar in almost every way, but the latter has a higher temperature tolerance.
Parylene is applied in a vacuum in a process known as "vapor deposition." The polymer begins as a powder and is placed in a vaporizer, which heats it and turns it into a gas; the vapor is heated again and sent into a room-temperature chamber to coat the substrate surface or object. The result is a thin, even coating that can reach and cover angles and crevices that may not be as strongly protected by liquid options.
With so many benefits, it's easy to see why parylene is one of the most popular coatings for a variety of projects and environments. Here are a few common examples:
There are many advantages to using Parylene compared to liquid conformal coating materials. Some of these benefits include:
Parylene displays unmatched thermal, chemical, moisture, and environmental barrier properties and is suitable for ruggedized use despite micron-level thicknesses.
The gaseous nature of the deposition process allows Parylene to coat surfaces evenly, including sharp points, deep crevices, and hard-to-reach areas. Parylene will not pull away from corners or edges and is entirely pinhole free.
Parylene can be used on a wide range of materials, including delicate substrates, and is highly effective without adding weight or mass.
Parylene has a low dielectric constant and can enhance signal processing speeds due to its superior moisture barrier characteristics.
Parylene polymerization takes place at room temperature, protecting the circuit board or other device being coated from thermal stress. The film does not cure in the conventional sense, reducing the need to wait through a "cure period," and places no mechanical or temperature stresses on fragile components.
Parylene film has low static and dynamic coefficients of friction which can be valuable for some applications where stickiness is an issue.
The transparency and clarity of Parylene film leaves surface features and printing clearly visible, to the benefit of quality assurance examination. This non-absorption of visible light also makes Parylene suitable for optical uses.
Parylene coatings can be as thin as 0.5 microns. This keeps it from interrupting processes or adding mass to key components.
Parylene doesn't readily react with other substances; it is both biologically and chemically inert.
Parylene's superior electrical dielectric properties make it ideal for insulating electronic components with minimal dimensional change. The dielectric strength of the film is greater than 5,000 volts per mil of coating thickness.
Parylene is an effective barrier against moisture, chemicals, biofluids, and biogases. The material is USP Class VI Compliant, can be sterilized, and has been approved by the FDA for use in the human body.
Parylene is safer for the environment than liquid coatings that often contain high VOCs.
Parylene has a well-earned reputation as the most popular conformal coating for a variety of important projects. From medical devices and aerospace mechanisms to consumer electronics and windows, this coating utilizes its unique properties to create unmatched protection and reliability.
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