Parylene
Parylene is a protective polymer material, also known as poly (p-xylene) or Parylene in Chinese. It can be vapor deposited under vacuum, and the excellent penetration of Parylene active molecules can form a transparent insulation coating with no pinholes and uniform thickness inside, at the bottom, and around the components, providing a complete and high-quality protective coating against acid, alkali, salt spray, mold, and various corrosive gases. Because Parylene is not a liquid, there will be no aggregation or bridging to form a meniscus during the coating process.
Why do neodymium iron boron permanent magnets need to be coated with Parylene?
Neodymium iron boron permanent magnet material is a high-performance and strong magnetic material, but it is very unstable in air. Larger magnetic materials are usually protected by electroplating or epoxy electrophoretic paint, while smaller magnetic materials, especially circular and cylindrical magnetic materials, are difficult to meet the requirements of use with the traditional protection methods mentioned above. The unique preparation process and excellent performance of Parylene enable it to fully coat small and ultra small magnetic materials without weak points. The magnetic materials can be immersed in hydrochloric acid for more than 10 days without corrosion. Currently, many small and ultra small magnetic materials internationally use Parylene as insulation and protective coatings.
Preparation and polymerization process of Parylene film
The commonly used method for preparing Pirolin is chemical vapor deposition (CVD), which is a process technology in which reactants undergo spatial gas-phase chemical reactions under gaseous conditions, directly generating solid substances on the surface of a solid substrate, and then forming a coating on the substrate surface. The preparation process of Parylene thin film is divided into three steps: monomer vaporization, cracking, and adhesion deposition on the substrate surface. 1. In a vacuum environment, solid tetrachlorodimethylbenzene dimer sublimates into a gaseous state at around 150 ℃; 2. At around 650 ℃, the tetrachloro-p-dimethylphenyl dimer decomposes into active 2,5-dichloro-p-dimethylene benzene with free radicals; 3. At room temperature (25 ℃), free state 2,5-dichloro-p-dimethylene benzene is deposited and polymerized on the surface of a solid substrate, forming a conformal film without pinholes.
The protective effect of Parylene coating: 1. It is resistant to acid and alkali corrosion and can solve the problem of corrosion by acidic or alkaline substances. 2. Low water, gas permeability, high barrier effect, can achieve moisture-proof, waterproof, rust proof, and slow down weathering effects. 3. Resistant to organic solvents (insoluble in general solvents). 4. The film layer is colorless and has high transparency, which does not affect the original appearance of the product. 5. The film layer has dustproof, moisture-proof, and waterproof breathable properties, which can make the product meet international dustproof and waterproof IP level specifications.