The working principle of vacuum coating

    The vacuum coating process is a process in which gaseous atoms or molecules are transported and deposited like a substrate in a vacuum environment. It usually includes the formation of deposits and the condensed growth after deposition.

    The physical vapor deposition (PVD) method means that the deposit is mainly formed by the vaporization of solid materials, such as the heating and evaporation of the material in the evaporation source, the bombardment and sputtering of the target material by ions, or although the evaporation source or sputtering source is used, On the way of the substrate, some atoms are ionized by gas discharge, which constitutes the so-called evaporation plating, sputtering plating and ion plating.

    The chemical vapor deposition (CVD) method refers to the formation of deposits mainly through gas chemical reactions. In the category of vacuum coating, there are low pressure CVD, plasma CVD and optical CVD. The decomposition, excitation and chemical reaction of the reaction gas are achieved by means of high temperature, discharge plasma and light irradiation.

    Nowadays, some called PVD method is not simply a physical process, and some also introduce reactive gas, which makes the deposit accompanied by a chemical reaction in the transportation process.

    The condensed growth of deposits on the substrate is not a simple random accumulation, otherwise it can only form an amorphous film. In fact, the structure of the film can be amorphous, as well as polycrystalline and single crystal. This is because the deposited atoms will migrate, and the strength and state of the migration of the atoms depend on the interaction between the atoms and the substrate, as well as the substrate temperature, gas pressure, ion bombardment and other factors. Especially when ions participate in the film formation process, the migration and interaction of atoms will be greatly enhanced, which will cause changes in the structure, phase composition, adhesion, internal stress, film formation temperature and other properties of the film.

 (huiputech)