Parylene P6

Of the various thin organic coatings that are already produced and applied in a vacuum using plasma polymerisation, the so-called "Parylene" coating has gained particular importance as a corrosion protection coating because of its special chemical resistance to almost all acids and alkalis and organic solvents as well as its good resistance to water vapour diffusion. The name Parylene has become a common abbreviation for the complete chemically more correct name Poly-Para-Xylylene, which stands out from other plastic and lacquer coatings due to a number of quite outstanding properties.

The field of application for Parylene is almost unlimited. It ranges from simple seals, pipes and vessels in industry to all kinds of sensitive electrical components such as printed circuit boards, sensors, flight control systems and many more. As Parylene is also biocompatible, it is very popular in medical technology for hearing aids, cannulas, implants, probes and endoscopes.

Parylene can be applied in suitable vacuum coating equipment in a layer thickness of 1 µm to approx. 50 µm on practically all materials such as plastics, metals, glass, ceramics, fabric, paper. It has found particular use in the corrosion coating of assembled printed circuit boards (PCB), magnets and electric motors, sensors for pressure and temperature measurements and sensors for level measurements of foodstuffs and chemicals, as well as in medical devices (biocompatible), in the watch industry and in safety engineering. The layer properties are characterised by the fact that already from a thickness of more than 0.5 µm, there are practically no more imperfections in the form of small "pinholes", thus creating a hermetically sealed layer that can only be penetrated by diffusion.

As a further property of these layers, in addition to the high dielectric strength (approx. 5 000 volts at 20 µm layer thickness), the high temperature resistance (F-types) from -150 °C to +300 °C should be emphasised. It is also very important that the thermal stress on the substrate during coating is extremely low, as the coating is carried out near room temperature between 20 °C and a maximum of 60 °C, so that even thermally sensitive substrate materials are suitable for coating.

Because of its chemical resistance, the parylene coating is also preferably used for medical devices that come into contact with body fluids, such as hypodermic needles, catheters or implants, as well as pacemakers and the like. Due to this physiological harmlessness, this parylene coating is also suitable for coating possibly allergy-triggering spectacle parts, watches or other jewellery items that could trigger skin irritation.