The evaporation system of pvd coating machine mainly refers to the film-forming device. There are many film-forming devices in the coating machine, including resistance heating, electron gun evaporation, magnetron sputtering, radio frequency sputtering, ion plating, and other methods. I will introduce the two methods of resistance heating and electron gun evaporation, as I have applied them more frequently.

 Electron gun evaporation is by far the most widely used evaporation method, which can evaporate any type of coating material. Its working method is to place the coating material in a crucible, make the evaporation source into a filament shape, use a specialized control cabinet, apply a strong current and high voltage to the filament. Due to the material of the filament being tungsten, it will generate heat and eventually emit electrons, Then, a certain magnetic field is used to gather it into a certain shape and drag it onto the crucible, forming an electron beam. Due to the extremely high temperature of the electron beam, it can melt any coated medicinal material. When the coated medicinal material is melted by the electron beam (some materials are directly sublimated), the molecules (atoms or ions) of the medicinal material move in a straight line in vacuum, and then encounter the substrate, they coagulate and grow in this way, Form a thin film! The most commonly used methods include making the deflection angle of the electron beam at 270 degrees, or running an e-line electron gun with an e-type trajectory, or a c-type electron gun with an electron beam deflection angle of 180 degrees and a c-type trajectory.

The biggest advantage of electron beam evaporation is that the spot of the electron beam can be adjusted freely, which can be used multiple times with one shot. The filament can be hidden to avoid pollution, and any coating material can be evaporated. It is easy to maintain, the evaporation speed can be controlled at will, the material decomposition is small, and the film density is high. Good mechanical strength.

The sputtering method is to bombard the surface of the target material with high-speed positive ions, and through kinetic energy transfer, the molecules (atoms) of the target material have enough energy to escape from the surface of the target material and condense to form a thin film on the product surface.

The thin film prepared by sputtering method has strong adhesion and high purity, and can simultaneously sputter multiple materials with different components. However, it has high requirements for the target material and cannot save resources like an electron gun.

At present, the most commonly used method is magnetron sputtering, which refers to applying a strengthened electric field parallel to the cathode surface to constrain electrons near the cathode target surface and improve ionization efficiency. It is the simplest type of operation, so it is widely used.