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The term coating is used in manufacturing processes for thin-film technology, optical fibers, magnetic tapes, compact discs( CD) or optical components, but also for the copper lamination of printed circuit boards. In coatings, various materials are applied that have functional, technical or protective tasks.

  1. Thin-film technology involves the application of individual layers of conductive and semiconductive materials. For this purpose, the materials to be applied are deposited from the gas phase and vapor-deposited onto the substrate at the appropriate locations. There are processes on a physical basis, physical vapor deposition( PVD), on a chemical basis, chemical vapor deposition( CVD), as well as processes with electron and laser beam evaporation.
  2. Optical fiber is the plastic layer applied to the surface of the transparent cladding glass of an optical fiber. This thin layer protects the glass fiber from minor damage such as scratches and from external influences. The coating consists of two layers: the primary coating and the secondary coating.
    Coating of optical components, photo:

    Coating of optical components, photo:

    The primary coating is a coating made of soft plastic. It surrounds the cladding glass directly or is applied to it. The primary coating is an acrylate that is applied immediately after the fiber has cooled and cured with UV irradiation. The thickness of the primary coating depends on the application and can be between 100 µm and 400 µm. The primary coating is not sufficient for complete protection of the glass fiber, so a second protective coating, the secondary coating, is applied around the primary coating. This depends on the fiber structure, it consists of plastic combinations and has a thickness of about 400 µm to 800 µm. The outer coating is firmly bonded to the primary coating. Both coatings ensure sufficient stability of the glass fiber and adequate protection against external influences.
  3. In the case of magnetic tapes and strips, a magnetizable material of iron oxide (Fe2O3) or chromium dioxide (CrO2) is applied to the polyester film substrate with a binder. The layer thickness is only a few µm (about 2 µm).
  4. For CDs, DVDs and high- resolution DVDs, the base material is polycarbonate. Several layers are applied to this disc on one or both sides. The first is an opaque layer to which a transparent recording layer is applied. The recording layer is the data carrier, which is protected from damage by a protective layer of lacquer or polymer plastic. The sprayed protective layer is cured under UV light.
  5. Plastic cards are coated with a protective layer during printing. For this purpose, plastic card printers have a YMCKO ribbon that prints the coating, the overcoat, after the color printing. The overcoat protects plastic cards for against damage, against UV light and can be printed with watermarks, making the plastic card tamper- proof.
  6. Solar cells are coated with an anti-reflective coating( ARC), which improves the absorption of sunlight and reduces reflection. As a result, solar cells with anti-reflective coating have higher solar electricity generation efficiency.
  7. In PCB manufacturing, coating is about applying a conductive surface to the uncoated base material.
    Copper-laminated base material for printed circuit boards, photo: conrad

    Copper-laminated base material for printed circuit boards, photo: conrad

    Such a coating can be applied by laminating a copper foil, by lamination, electrical or chemical additive processes or by printing processes. During further production, the conductor tracks are etched out of the two-dimensional coating using exposure and etching processes.
Englisch: coating
Updated at: 19.04.2019
#Words: 547
Links: fibers, call deflection (ETSI) (CD), copper (Cu), indium (In), application (app)
Translations: DE

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