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Study on Characteristics of Parylene Vapor Deposition Coating Process

2019-05-21 来源:亚科官网
 
Poly-para-xylylene (parylene) is a high molecular polymer, also known as "parylene " in China. It is a new coating material developed and applied by Union Carbide Co. in the United States in the mid-1960s. According to the molecular structure, Parylene can be divided into N type, C type, D type, HT type and so on.
What is Parylene?
Parylene is a protective polymer material. It can be vapor deposited under vacuum. The good penetrating power of Parylene active molecules can form pinholes inside and outside the component. A uniform thickness of transparent insulating coating provides a complete high-quality protective coating to protect the components against acid, alkali, salt spray, mold and various corrosive gas parts. Because Parylene is not a liquid, it does not aggregate during coating. The bridge forms a meniscus.
Unique protective features of Parylene vapor deposited coating
An electronic product is in a high-humidity closed system environment in which a mixture of various chemical substances and water molecules coexists, and the wiring of the circuit and components are often corroded, resulting in extremely poor reliability of the product. The printed board assembly of this product has adopted DC1-2577 conformal coating produced by Dow Corning Company of the United States. The protective coating of S01-3 polyurethane varnish used in most domestic electronic products can not solve the corrosion problem of lines and components. . Later, the company introduced the production line of the Pyrene vapor deposition coating process to solve the reliability of the electronic product.
Through the long-term application of the Parylene vapor deposition process, we have concluded that the Parylene vapor deposition process has the following unique protective advantages:
(1) "non-porous"
The parylene coating is prepared by a unique vacuum vapor deposition process and is a conformal polymer film coating that is "growth" from the active small molecules on the surface of the substrate. Since it is formed under vacuum, the most important feature of the process is "non-porous", which can be applied to surfaces of various shapes, including sharp edges, cracks and inner surfaces.
(2) can provide a true pinhole-free protective layer
The parylene precipitation process is to heat and gasify the xylene ring dimer and then pyrolyze it into free gas phase molecules, and then adsorb it on the substrate in a vacuum and room temperature to form a film, which is very airtight. Protective film. Since the coating does not contain a solvent, it overcomes the disadvantage that the solvent-based paint used in the past will inevitably leave many fine pinholes due to solvent evaporation during the drying process, and can provide a true pinhole-free protective film.
(3) Unique protection performance combined with independent protection performance and overall protection performance of each local point
Since the parylene coating is deposited at room temperature with a double free radical active monomer, the monomer sinks first onto the substrate of the printed board assembly, and then the active bonds of the monomers are bonded, thereby Connected into one piece to form a monolithic film. Through long-term use, we found that the points of the coating layer are an independent protection point. When the partial coating is damaged, it will not seriously affect the protection of the coating in the surrounding area, and the points of the coating layer pass through. The chemical bonds are joined together to form a whole, which enhances its protective properties.
Related links: Parylene
Edited by Suzhou Yacoo Science Co., Ltd.