Principle and performance of vacuum evaporation coating machine

   The preparation of coatings in vacuum, including metal, semiconductor and insulator element or compound film deposited amorphous. Although chemical vapor deposition also uses vacuum, low pressure or plasma and other means, but the general vacuum coating is a physical method of depositing thin films. Vacuum coating has three forms, namely, evaporation, sputtering and ion plating.

It is deposited on a solid surface by heating and evaporating a material called evaporation coating. This method was first proposed by M. Faraday in 1857, and it has become one of the most commonly used coating technologies. Evaporation and other vacuum coating method, compared with a high deposition rate, system element and plate is not easy to thermal decomposition of the compound membrane. A device used for vacuum evaporation is called evaporation coating machine.

In the vacuum of coating equipment, the film can prevent the pollution of the film and the surface of the coating, eliminate the space collision, improve the density of the coating and the special function of the preparation of a single compound. For large area coating, the method of rotating substrate or multi evaporation source is used to ensure the uniformity of film thickness. The film thickness depends on the evaporation source evaporation rate and time (or depends on the load, and the distance from the source) and the substrate. From the evaporation source to substrate distance should be less than vapor molecules in the residual gas mean free path, in order to avoid steam and residual gas molecule collision caused by chemical action. The exhaust system is generally composed of mechanical pumps, diffusion pumps, pipes and valves. At present, there are many kinds of evaporation sources, such as resistance heating, electron beam heating, induction heating, arc heating and laser heating. The average kinetic energy of the vapor molecule is about 0.1 ~ 0.2 electron volts. Film thickness can be from a few hundred to a few microns.

In order to improve the uniformity of coating thickness, the vacuum chamber plated clip with planet mechanism or rotation and revolution of the motion device, such as planetary motion mode. This mode of motion into a good film uniformity, step coverage performance is good, plating the heavy load can make full use of the useful space of the vacuum coating chamber, is most frequently used mode of motion. Evaporation coating machine mainly consists of four parts, vacuum chamber, exhaust system, evaporation system and electrical equipment.

Evaporation of material, such as metal and compounds in the crucible or hanging on the wire as evaporation source, a workpiece to be plated, such as metal, ceramics, plastics, such as base piece is placed in a crucible in front. It is deposited on a solid surface by heating and evaporating a material called evaporation coating. Electrical equipment, including measurement of the vacuum and film thickness and the console, etc.. Therefore, the exhaust system is required to obtain low air pressure in a relatively short period of time to ensure a fast operating cycle, and also to ensure that the vapor deposition is quickly excluded from the vapor source and the surface of the work produced by the gas. In order to improve the pumping speed, a mechanical booster pump can be added between the mechanical pump and the diffusion pump. The atoms or molecules of an evaporating substance deposited on the surface of the substrate in the form of condensation. Evaporation type coating machine commonly used evaporation source is used to heat the membrane material to make vaporization of the device. The vacuum chamber is the place where the plating part and the coating are arranged, the diameter is generally 400~700mm, the high 400~800mm, the stainless steel is made, and the water cooling device is used. After the system is pumped to a high vacuum, the heating crucible causes the material to evaporate. Evaporation system includes an electrical apparatus for evaporation source and heating evaporation source.