There are two common coating processes of vacuum coater, evaporation and splashing. These two processes are the most popular and widely used at present. Then, it naturally attracts more attention from other processes. The following is a summary of four common problems about these two processes of vacuum coater, hoping to help you:
1、 Why can vacuum coating be made into different colors and seven colors?
Because after the vacuum evaporation, we need to spray a layer of UV varnish, which can be painted in different colors. Evaporation can be made into seven colors by depositing some silicide, but it is relatively thin. It can be seen from near, but not from far,; Seven colors can be obtained by reactive sputtering with CSI, Co, Si and other materials, or colorful colors can be obtained by low-temperature multi-layer coating with different colors. And water electroplating is generally metal color, to present other colors need to apply UV topcoat, and then UV irradiation.
2、 What is the reason for the difference of adsorption between vacuum evaporated and vacuum sputtered coatings?
Evaporation is adhesion, sputtering is strong adsorption of positive and negative electrodes, so the adsorption of sputtering is more uniform, the density is greater, and the hardness is greater. The price of sputtering is 10% - 20% higher than that of evaporation.
3、 Why can vacuum coating be made semi transparent and non-conductive?
It is not completely non-conductive, because of the discontinuity of molecules in the film state, metals or metal compounds have conductivity, but the conductivity is different. However, when the metal or metal compound is in a thin film state, its corresponding physical properties will be different. Among the 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 nm, it is not conductive; The silver white effect and conductivity of aluminum are slightly worse than that of silver, but when its thickness is 0.9 nm, it already has conductivity. Why is that? That's because the continuity of silver molecule is not as good as that of aluminum, so its conductivity is poor under the relative film thickness. In fact, we use the principle of poor molecular continuity of some metals to control its thickness in a certain range, so that it has a silver white appearance and high resistance. It can be seen that the effect of metal non-conductive film is directly related to its film thickness. Only in the corresponding film thickness, the corresponding 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 less than 5 nm. Can we use silver to make the metal non-conductive film we need? The answer is No. Because the thickness of silver below 5 nm is basically transparent and colorless, although it is not conductive, it can not have the effect of silver white reflective film at the same time. Similarly, aluminum is not good. Therefore, we need a kind of metal material which can be plated with silver white metallic luster and high resistance. We use tin or indium and indium tin alloy with purity above 99.99%. Tin with thickness less than 30 nm has poor continuity, but can achieve silver white metallic luster and high resistance. Indium is the same, but the silver white reflectance of indium is better than that of tin. Because the price is higher, we use indium tin alloy, which can not only get a non-conductive film, but also get a whiter and brighter reflective metal effect! Indium tin non-conductive film is translucent, so we require the substrate to be transparent or black. Because indium and tin begin to melt at 250 ℃, the temperature of evaporation is relatively low, so the current and time of heating, melting and evaporation are relatively low.
4、 Why is the aluminum coating of vacuum coating not conductive?
Because the coating has three layers in total, the outermost UV varnish has the function of curing wear-resistant insulation after UV irradiation, but once the film is damaged, it will conduct electricity.
There are not only four kinds of common problems in vacuum coating machine evaporation coating process and splash coating process, but they are the most common and most concerned problems.