Introduction to the formation of pollution in vacuum devices and their effects

During the manufacturing process of the vacuum device, the surface of the parts will inevitably be contaminated with grease, sweat marks, polishing paste, flux, metal shavings, grease stains, etc. At the same time, the pollutants adsorb a large amount of gas at atmospheric pressure in a vacuum environment. These gases are released and constitute a factor limiting the ultimate vacuum of vacuum equipment.
    During the use of the vacuum device, the parts are also polluted due to the use conditions. For example, the vacuum drying system is often contaminated by the evaporation material; the inner wall of the vacuum coating machine is contaminated by the evaporation material; the ion beam etching equipment The inner wall will be polluted by sputter; the filament of the electron gun in vacuum will form a metal film on the surface near it due to high temperature evaporation; the mechanical pump oil and diffusion pump oil in the vacuum system are the source of pollution, which will cause the equipment to form inside after long-term work. Oil film. These pollutions also affect the performance of the equipment.

    In all kinds of vacuum process production, for example, electric vacuum process, vacuum coating process, vacuum welding process, etc. all attach great importance to vacuum hygiene issues. In the electric vacuum process, parts that are required to be assembled into a high-vacuum environment must be carefully cleaned beforehand. Otherwise, various pollutants can become a source of a large amount of gas and steam, which will prolong the exhaust time of the vacuum device and make it difficult to obtain a high vacuum. . In vacuum coating technology, the cleaning of the substrate (substrate) surface is also very important. The surface of the substrate exposed to the atmosphere is generally contaminated, adsorption, chemical reaction, leaching and drying, mechanical treatment, and diffusion and segregation processes. It will increase the surface pollutants of various ingredients. The surface of the substrate must be clean before coating, otherwise the coating will not adhere well to the surface.

    Environmental pollution has a great impact on vacuum hygiene. Environmental pollutants come from air, floors, walls, ceilings, dust and cotton linters in overalls. To this end, the production of some special parts of the vacuum device is required to be carried out in a clean room or an ultra-clean room. In the manufacture of tubes, pipe racking and part handling must be carried out in a well-sealed clean room. The air must be filtered through two or more poles with a relative humidity of less than 50%. Vacuum hygiene involves all aspects of the vacuum system, involving the vacuum device itself and its requirements for the surrounding environment. This is a question worthy of attention.

Several types of vacuum chamber contaminants

(1) Grease: lubricants, vacuum greases, etc. contaminated during processing, installation and operation;

(2) Water droplets: hand sweat during operation, saliva when blowing glass, etc.;

(3) Surface oxide: surface oxide formed by long-term exposure or placement of a readily oxidizable material in a humid atmosphere;

(4) Acid, alkali, and salt substances: residual substances after cleaning, hand sweat, minerals in tap water, etc.;

(5) Dust and other organic matter in the air.