Frequently Asked Questions about Evaporation Process and Sputtering Process of Vacuum Coating Equipment

Summary:There are two common coating processes in vacuum coating equipment, evaporation and sputtering. Thes...
There are two common coating processes in vacuum coating equipment, evaporation and sputtering. These two processes are currently the most popular and widely used. Then, its attention is naturally much higher than other processes. The following is a sincere vacuum. The technology has summarized four common problems about the two processes of vacuum coating machine for you in detail, and hope to help you:
1. Why can vacuum coating be made into different colors and seven colors?
Because after the vacuum evaporation, a layer of UV varnish topcoat is sprayed, and different colors can be made on this topcoat. Evaporation can be made into seven colors by plating some silicides, but it is relatively thin. Layers of different colors of coating to present colorful.
Second, the reason for the difference in adsorption between vacuum evaporation and vacuum sputtering coatings?
Evaporation is adhesion, and sputtering is the strong adsorption of positive and negative electrodes, so the adsorption of sputtering is more uniform, density, and hardness. The price of sputtering is 10%-20% more expensive than that of evaporation.
3. Why can vacuum coating be semi-transparent and non-conductive?
It is not completely non-conductive, using the discontinuity of molecules in the thin film state, metals or metal compounds have conductivity, but the conductivity is different. However, when the metal or metal compound is in the state of a thin film, its corresponding physical properties are different. Among conventional coating materials, such as: silver is the metal with the best silver-white effect and conductivity, but when its thickness is less than 5 nanometers, it is not conductive; the silver-white effect and conductivity of aluminum are slightly worse than silver, but it is not conductive. When the thickness is 0.9 nanometers, it is already conductive. Why is this so? It is because the continuity of silver molecules is not as good as that of aluminum, so its conductivity is worse under the relative film thickness. Our vacuum metallized non-conductive film actually uses the principle of poor molecular continuity of some metals, and controls its thickness within a certain range to make it have a silver-white appearance and high resistance. It can be seen that the effect of the metal non-conductive film is directly related to its film thickness. Only under the corresponding film thickness, a correspondingly stable silver-white non-conductive film can be obtained.
As mentioned above, silver with the best silver-white effect and conductivity is non-conductive when its thickness is below 5 nanometers. Then, can we use silver to make the metal non-conductive film we need? The answer is no . Because silver with a thickness of less than 5 nanometers is basically transparent and colorless, although it is not conductive, it cannot have the effect of silver-white reflective film at the same time. Likewise, aluminum doesn't work either. Therefore, we need a metal material that can be plated with silver-white metallic luster and has a large resistance. We use tin or indium and indium-tin alloys with a purity of more than 99.99%. Tin with a thickness of less than 30 nanometers has relatively poor continuity, but can achieve silver-white metallic luster and has a large resistance. The same is true for indium, but the silver-white reflectivity of indium is better than the appearance of tin. Because of the higher price, we use indium-tin alloy, which can not only obtain a non-conductive film but also a whiter and brighter reflective metal effect! Indium-tin plating does not The conductive films are all translucent, so we require the substrate to be plated to be transparent or black. Because indium-tin plating starts to melt at 250 degrees, the evaporation temperature is relatively low, so the current and time for heating, melting and evaporation are relatively low.
Fourth, why is the aluminum plating of vacuum coating not conductive?
Because the coating has three layers in total, the UV varnish on the outermost layer plays the role of curing and wear-resistant insulation after being irradiated by UV, but once the film is damaged, it will conduct electricity.

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