Parylene-coated magnets are created by applying a parylene coating to the surface of the magnets. Compared to conventional coating treatments, this technology produces a thin layer with excellent characteristics such as high pressure and corrosion resistance.
Notably, the coating thickness can be controlled between 1 micron and 20 microns. This ultra-thin film meets the coating requirements of high-end magnets.
What is Parylene?
Parylene is a polymer material. It can be deposited in the gas phase under vacuum. Parylene active molecules have good penetration capabilities and can be used on the exterior and interior of various shaped magnets, forming coatings between 0.1-100μm thick.
The uniform, dense, pinhole-free, transparent, and stress-free coating provides a complete, high-quality protective coating for devices. Because Parylene coating is generated through vapor deposition, it doesn’t form a meniscus on the surface of the device. Therefore, Parylene is an excellent coating material for moisture-proofing, mold-proofing, corrosion resistance, and salt spray resistance.
Types of Parylene
Based on differences in molecular structure, there are several types including Parylene N, C, D, HT, F, etc.
Parylene-coated Magnets
| Parylene-coated neodymium magnets: Neodymium magnets are high-performance strong magnetic materials, but they are oxidized easily in air. Larger neodymium magnets are usually protected with electroplating or epoxy coatings. For smaller magnets, especially ring and cylindrical shapes, these methods often fail to meet usage requirements. Parylene’s unique preparation process and excellent properties allow it to fully coat small and ultra-small magnets. These Parylene-coated magnets can resist corrosion in hydrochloric acid for over 10 days.
| Parylene-coated ferrite magnets: Ferrite magnetic rings are widely used, with many varieties and high production value. They are mainly used in various inductive components such as filter cores, transformer cores, and radio cores, and are also key materials for magnetic recording components.
Ferrite magnetic ring cores are small and easily worn during winding. Parylene’s good lubrication and high insulation properties effectively reduce wear during winding. The controllable coating thickness and ultra-thin insulating layer can increase the dielectric and high-voltage resistance of the magnetic material.
| Parylene-coated samarium cobalt magnets: Samarium cobalt magnets easily break during use or assembly. Parylene’s dense and uniform film layer can enhance magnet strength and reduce the chance of samarium cobalt magnets breaking.
Advantages of Parylene-coated Magnets
| Parylene coating has a very low water vapor transmission rate, providing a better barrier against water and oxygen. Its protective performance is significantly superior to traditional processes like epoxy coating, or electroplating.
| Magnets treated with electroplating have a salt spray resistance of 70-100 hours. Parylene-coated magnets can resist salt spray for 300-500 hours, 4-5 times longer.
| Parylene coating forms a uniform insulating protective layer on the magnet surface, overcoming the acid-intolerance defect of common epoxy treatment.
| Parylene coating is formed directly from gaseous monomers to solid coating. The coating grows from the substrate surface outward, forming a uniform thickness layer that is pinhole-free even below 1 micron. As the coating of Parylene-coated magnets forms at room temperature, it prevents stress problems caused by expansion during curing.
| Parylene coating is colorless and highly transparent, not affecting the original appearance of the magnets.
The Production Process of Parylene-coated Magnets
The common method for preparing Parylene is Chemical Vapor Deposition (CVD). This process involves three steps: vaporization of the monomer, pyrolysis, and deposition on the substrate surface.
| In a vacuum environment, the solid raw material gradually absorbs heat and sublimates into a gaseous state in the vaporization chamber at around 150°C as the temperature rises.
| The sublimated gas then enters the pyrolysis chamber, where it decomposes at around 650°C into active Parylene monomers with two dangling bonds.
| At room temperature (25°C), the free active Parylene monomers deposit and polymerize on the magnet surface, forming a dense protective film.
The market demand is driving magnets towards miniaturization, and the protection needs of miniaturized magnetic materials are promoting the widespread application of Parylene coatings. With technology development and market demand, Parylene will play a protective role in various magnets.
Applications of Parylene Coating
| Healthcare: Parylene is a high-purity coating material that provides devices with excellent surface lubrication, biocompatibility, and high reliability. It is suitable for use in various types of implants.
| Sensors: A thin Parylene coating can improve the environmental adaptability and reliability of sensors. Applicable areas include microwave, acoustic, piezoelectric, radiation, chemical, temperature, and various other sensors. It can be used in environments such as freshwater, seawater, refineries, chemical plants, blood and body fluids, as well as radiation environments.
| Printed Circuit Boards (PCBs): Parylene coating is also widely applied to PCBs. It maintains high reliability in salt spray tests and other harsh environments, without affecting the functionality of resistors, thermocouples, and other components on the board.
Parylene-coated Magnets Provider
At Tengye, we’re thrilled to be early participants in your new projects. Our passion for magnets extends from material selection and design optimization to providing magnetic solutions. We hope to bring our knowledge and experience to the forefront by actively engaging in your upcoming projects. Work with our magnet experts to get the right magnet solution.
Image Source: Advancedcoating & Mpcomagnetics & Plasma & Sinvacon & Vsiparylene & Web
