The working principle of vacuum coating is that the fil […]
The working principle of vacuum coating is that the film evaporates and crystallizes on the surface of the workpiece at high temperature. Because the air will cause resistance to the evaporated film molecules and cause collisions to make the crystals rough and dull, it must be under high vacuum to make the crystals fine and bright. If the vacuum is not high, the crystals will lose their luster. The early vacuum coating relies on the natural scattering of the evaporating body, combined with poor work efficiency and low gloss. Now add the intermediate frequency magnetron sputtering target and use the magnetron sputtering target to accelerate the evaporated molecules of the film body under the action of the electric field to bombard the target material, sputtering a large number of target material atoms, and the neutral target atoms (or molecules) are deposited on the The film is formed on the substrate, which solves the types of films that cannot be processed by natural evaporation in the past, such as titanium plating and zirconium plating.
Intermediate frequency equipment must add cooling water, because its frequency is high and current is large. When the current flows in the conductor, there is a skin effect, and the electric charge will accumulate on the surface area of the conductor, which makes the conductor generate heat. Therefore, a mesoporous tube is used as the conductor to add water to cool it.
(mainly cylindrical targets) Why should it be cooled with water? The magnetron sputtering target generates high temperature when it is fired that will deform the gun, so it has a water jacket to cool the gun. There is also an important reason why magnetron sputtering can be considered as one of the outstanding achievements in coating technology. It has high sputtering rate, low substrate temperature rise and good film-substrate bonding force.
The motion law of electrons in a non-uniform electromagnetic field is studied from a deeper level, and the more general principle of magnetron sputtering is discussed, and the lateral inhomogeneity and symmetry of the magnetic field are the essential reasons for magnetic confinement. Magnetron sputtering can be considered as one of the outstanding achievements in coating technology. It has the advantages of high sputtering rate, low substrate temperature rise, good film-substrate bonding force and stable device performance.
In addition, according to the type of coating machine and the processed products, the requirements for cold water will also be different. For ordinary material evaporation, the cooling water tower can be used with a water temperature of about 30 °C. If the temperature of hard parts is involved, it will be required to be 15-25 °C. . You must use the chiller
In another case, the application of the cryogenic cold trap is that the exhaust system of the vacuum coating of the auxiliary pumping system adopts a diffusion pump, a mechanical pump, a Roots pump, a cryogenic cold trap, etc. The cryogenic cold trap is also indispensable. part
1. If the coating machine uses a diffusion pump, a cold trap is generally added to the pump port to capture oil molecules. This kind of refrigeration does not require heating and rewarming, and can be used in a general freezer (about -20°) or deep cooling (about -140°).
2. If the coating machine wants to increase the pumping speed, it is generally necessary to add a cryogenic device with a return temperature device. Refrigerate when pumping, and return to temperature before venting.
3. There is also a case of winding coating. When the film is aluminized, it should be cooled to about -15 °, and it should be warmed to room temperature before deflation.