Characteristics of vacuum coating

Compared with wet coating technology, vacuum coating technology has the following advantages:

(1) The selection of film material and substrate material is wide, the film thickness can be controlled, and a variety of functional films with different functions can be prepared.

(2) The film is prepared under vacuum condition, the environment is clean, the film is not easy to be polluted, so you can get good density, high purity, uniform coating film.

(3) The bonding strength between the film and the matrix is good, and the film is firm.

(4) The coating will not produce waste liquid after drying, and will not cause pollution to the environment.

Vacuum coating technology mainly includes vacuum evaporation coating, vacuum sputtering coating, vacuum ion coating, vacuum beam deposition, chemical vapor deposition and other methods. Except for chemical vapor deposition, all other methods have the following characteristics in common:

(1) All kinds of coating technology need a specific vacuum environment, in order to ensure that the film material in the process of heating evaporation or sputtering formed by the movement of vapor molecules, not by the collision of a large number of gas molecules in the atmosphere, block and interference, and eliminate the adverse impact of impurities in the atmosphere.

(2) All kinds of coating processes need to have an evaporation source or target to make the film material evaporate into gas. As a result of the continuous improvement of the source or target, the selection of film-making materials has greatly expanded. Whether metal, metal alloys, intermetallic compounds, ceramics or organic materials, all kinds of metal and dielectric films can be steamed, and different materials can be steamed at the same time to obtain multilayer films.

(3) Evaporation or sputtering film materials, in the process of forming a film with the workpiece to be plated, can be more accurate measurement and control of film thickness, so as to ensure the uniformity of film thickness.

(4) Each film can control the composition and mass fraction of residual gas in the coating chamber through a fine-tuning valve to prevent oxidation and evaporation of the material, reduce the mass fraction of oxygen to low, and can be filled with inert gas, which is impossible to achieve with wet coatings.

(5) Due to the continuous improvement of painting equipment, the painting process can be continuous, thus greatly improving the output of products, and causing environmental pollution in the production process.

(6) Because the film is prepared under vacuum conditions, the film has high purity, good compactness, bright surface and no need for reprocessing, so that the mechanical and chemical properties of the film are better than electroplating film and chemical film. [2]