Application of parylene coating materials in medical devices

Parylene is a protective polymer material that is formed into a protective film by vacuum vapor deposition. The film has uniform thickness, dense pinhole-free, transparent and stress-free, and has excellent electrical insulation and protection. It is a molecular grade coating material developed by American Union Carbide Company in the mid-1960s. It is the common name of the unique poly-P-xylylene polymer series. It is also the only solid-state coating in military standards.

Parylene's characteristics

Parylene currently used mainly includes Parylene N, Parylene C and Parylene D. The common point is that it is highly inert and highly pure, and each model has its own characteristics: Parylene N has high breakdown strength and has Low frequency-independent dielectric constant; Parylene C provides excellent combination of electrical and physical properties, including low permeability in hot flashes and corrosive gases; Parylene D delivers excellent physical and electrical properties at elevated temperatures Improved thermal stability. Parylene HT is a combination of materials with the advantages of the above three materials. The following mainly introduce Parylene N and Parylene C as examples to introduce the main characteristics of Parylene.

1. The friction coefficient is small

Since the Parylene coating material is deposited under vacuum, it is a protective material formed by repolymerization of cracked molecules. It is a molecular-scale growth, and the resulting coating is dense and stable, has a small friction coefficient, and increases with the thickness of the coating. The friction coefficient is reduced. When the thickness is 0.5 μm, the friction coefficient is only half of that of the silicon coating layer, and the friction coefficient when the thickness is 2 μm is only equivalent to 1/4 of the coating friction coefficient of 0.5 μm thick.

2. physical and mechanical properties

Parylene materials have good physical and mechanical properties. The physical and mechanical properties of the commonly used coatings are shown in Table 1. As can be seen from the table, the parameters such as tensile strength, coefficient of linear expansion and hardness are relatively stable. The range of variation is small and the coefficient of friction is small.

3. The comparison of parylene and common coating function

Parylene is highly inert and highly pure, and has a low dielectric constant and dielectric loss. Due to its high purity, low water vapor permeability and no ionic contamination, Parylene is immune to moisture. Since the curing of Parylene is automatically generated and completed before deposition, the substrate does not involve problems such as curing stress, solvent dissolution characteristics, and deposition temperature limitations of the film coating.

Application of Parylene Coating Materials in Medical Devices

The medical application is mainly after the application of Parylene, the film formed on the surface of the product has the characteristics of biocompatibility and isolation lubricity, it has great significant for the production of catheter, the needle, the skeletal prosthesis, the pacemaker, the peeping optical lens, which is enough to cause a technological revolution in the domestic medical industry. It has no effect on human blood and is bio-corrosive. It has been approved by the US Food and Drug Administration (FDA) for long-term implantation in humans.

Edited by Suzhou Yacoo Science Co., Ltd.