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Why do the PVD vacuum coating machines need to be cleaned?

Why do the PVD vacuum coating machines need to be cleaned?

2020-10-31

Why do the PVD vacuum coating machines need to be cleaned?

 vacuum coating machine

From Various vacuum production processes, such as vacuum coating process, vacuum welding process, electric vacuum process, etc., are very particular about the vacuum hygiene of the equipment. In the electric vacuum process, the parts that are to be placed in a high vacuum state must be cleaned first, otherwise various vacuum contaminants will become a large gas source, which will extend the vacuuming time of the vacuum device, and Obtaining a vacuum causes certain difficulties. The vacuum coating machine takes into account the adhesion of the film, so the cleaning of the equipment is very important.

 

In the electric vacuum process, through various cleaning methods, the adhesion of grease, dust, surface attachments, metal fines, excess oxide film, graphite film and other contaminants can be completely removed from the equipment, thereby improving the life of the electric vacuum machinery And mechanical reliability.

 

In the PVD vacuum coating process technology (including glass coating process technology), the cleaning treatment of the substrate surface is more important. Most of the substrate surface exposed to the atmosphere will be contaminated. In terms of the physical state of pollutants, these surface pollution can be liquid, gas or solid, and can exist in the form of loose particles, membranes, etc. In terms of the chemical characteristics of pollutants, these surface pollution can be inorganic or organic, and can be in a covalent state or an ionic state.

 

PVD Vacuum coating equipment has many sources of pollution, and its surface formation process is often the first pollution. Adsorption phenomena, drying and leaching processes, chemical reactions, mechanical treatments, and diffusion and segregation processes all increase various surface contaminants. The surface of the plated part before coating must be clean, otherwise the plated film will not have good adhesion. This is also true in the vacuum diffusion welding process. The strength of the welded joint is closely related to the surface cleaning treatment.

 

In the high vacuum coating machine, the cleaning work is more important. With a good cleaning effect, the out-gassing rate of equipment parts and materials can be reduced by several orders of magnitude. For example, stainless steel, after long-term exposure to the atmosphere, if no treatment is done, it will have an out-gassing rate of about 2.7×10⁻¹Pa·L/(s·m²) after pumping for 1 hour; After pumping for 4 hours, the air output rate can be reduced to 1.3×10⁻³Pa•L/(s•m²); after baking at 250°C for 15 hours, it can be further reduced to 1.3×10⁻⁶Pa•L/(s •M²) out-gassing rate. Having a good vacuum cleaning process can effectively increase the ultimate vacuum of the equipment.


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