The vacuum coating process has strict requirements for the application environment. For the conventional vacuum process, its main requirements for vacuum sanitation are: there is no accumulated pollution source on the parts or surface of the equipment in the vacuum, the surface of the vacuum chamber is smooth and free of soft tissue, pores and corner space, so the weld in the vacuum machine will not affect the vacuum, and the high vacuum machine shall not use oil as lubricant. The oil-free ultra-high vacuum system should avoid the influence of oil vapor on the purity, working performance or surface characteristics of the working medium. The ultra-high vacuum metal system often uses 1Cr18Ni9Ti as the structural material. The laboratory or workshop where the vacuum coating machine should be kept clean and sanitary.
In the process of vacuum coating, the surface cleaning treatment is very important. Basically, before all substrates are loaded into the coating vacuum chamber, they must go through the pre-plating cleaning process to achieve the degreasing, decontamination and dehydration of the work-piece.
The main sources of surface pollution of plated parts are: dust, sweat, grease, polishing paste, oil, lubricating oil and other substances will be adhered to during processing, transmission, packaging and other processes; Gas adsorbed and absorbed on the surface of equipment parts; The oxide film formed on the surface of the parts of the coating machine in wet air. For pollution from these sources, most of them can be removed by degreasing or chemical cleaning.
Do not store cleaned work-pieces in the atmospheric environment. In order to reduce dust contamination and clean the storage of work-pieces, often use cleaning cabinets or closed containers to store the work-piece. The glass substrate need to store in a freshly oxidized aluminum container, which can reduce the adsorption of hydrocarbon vapor. Because newly oxidized aluminum containers will preferentially adsorb hydrocarbons. Surfaces sensitive to water vapor or highly unstable are usually stored in a vacuum drying oven.
The basic requirements of the vacuum coating process on the environment mainly include: high cleanliness in the vacuum room, dust free in the coating room, etc. In some areas, the air humidity is relatively high, so before plating, not only need to clean the components in the substrate and vacuum chamber, but also need to do the baking and degassing work. In addition, in order to prevent oil from entering the vacuum chamber, it is also necessary to pay attention to the oil return and oil blocking measures of the refueling diffusion pump.
Post time: Feb-18-2023