Compared with wet coating technology, vacuum coating technology has the following advantages:
(1) The film and the substrate are widely selected, and the film thickness can be controlled to prepare a functional film having various functions.
(2) The film is prepared under vacuum conditions, the environment is clean, and the film is not easily contaminated, so that a film having good compactness, high purity, and uniform coating can be obtained.
(3) The film has good bonding strength with the substrate, and the film is firm.
(4) Dry coating does not produce waste liquid or environmental pollution.
Vacuum coating technology mainly includes vacuum evaporation plating, vacuum sputtering plating, vacuum ion plating, vacuum beam deposition, chemical vapor deposition and the like. In addition to chemical vapor deposition, several other methods have the following common features:
(1) All kinds of coating technologies require a specific vacuum environment to ensure the movement of vapor molecules formed by the film forming material during heating evaporation or sputtering, without being hit, blocked and interfered by a large number of gas molecules in the atmosphere. Eliminate the adverse effects of impurities in the atmosphere.
(2) Various coating techniques require an evaporation source or target to convert the vapor-deposited material into a gas. Due to the continuous improvement of the source or target, the selection range of the film-forming material is greatly expanded. Whether it is a metal, a metal alloy, an intermetallic compound, a ceramic or an organic substance, various metal films and dielectric films can be vapor-deposited, and simultaneously A multilayer film is obtained by vapor deposition of different materials.
(3) The film-forming material evaporated or sputtered can be relatively accurately measured and controlled in the process of forming a film with the workpiece to be plated, thereby ensuring the uniformity of the film thickness.
(4) Each film can accurately control the composition and mass fraction of residual gas in the coating chamber through the trim valve, thereby preventing oxidation of the vapor deposition material, reducing the mass fraction of oxygen to a minimum, and filling the inert gas. Etc. This is not possible with wet coatings.
(5) Due to the continuous improvement of the coating equipment, the coating process can be continuously realized, thereby greatly increasing the output of the product, and the environment is not polluted during the production process.
(6) Since the film is formed under vacuum conditions, the film has high purity, good compactness, and the surface is bright and does not need to be processed, which makes the mechanical properties and chemical properties of the film better than that of the plating film and the chemical film.