The modern coating equipment is mainly composed of vacuum chamber, vacuum acquisition part, vacuum measurement part, power supply part, process gas input system, mechanical transmission part, heating and temperature measuring unit, ionic evaporation or sputtering source and water cooling system.
1. Vacuum chamber
The coating equipment mainly has continuous coating production line and single-chamber coating machine in two forms, due to mold coating have higher requirements for the heating and mechanical transmission parts , and the mold shape, size vary widely, continuous coating production line is usually difficult to meet requirements, to be used single-chamber coating machine.
2. Vacuum acquisition part
Due to the high adhesion requirements of the coating of the mold parts, the coating process before the background vacuum is preferably higher than 6mPa, and the vacuum degree can reach 0.06mPa or more after the coating process is completed, so that the vacuum is selected properly to achieve the high degree of vacuum is crucial.
Up to now, there is not a kind of pump that can work from atmospheric pressure to close to ultra high vacuum. Therefore, the acquisition of vacuum is not a vacuum equipment and method can be achieved, it must be combined with several pumps, such as mechanical pump, molecular pump system, etc.
3. Vacuum measurement part
The vacuum measurement part of the vacuum system is to measure the pressure in the vacuum chamber. Like a vacuum pump, no vacuum meter can measure the entire range of vacuum, and many kinds of vacuum gauges are made according to different principles and requirements.
4. Power supply part
The target power supply mainly includes DC power supply and intermediate frequency power supply; the workpiece itself usually needs DC power supply, pulse power supply, or radio frequency power supply.
5. Process gas input system
The process gas, such as argon (Ar), krypton (Kr), nitrogen (N2), acetylene (C2H2), methane (CH4), hydrogen (H2) and oxygen (O2), generally are supplied by gas cylinder, and then pass into the vacuum chamber through the gas pressure reducing valve, globe valve, pipe, gas flowmeter, piezoelectric valve, solenoid valve.
The advantage of this gas input system is that the pipeline is simple, light, and easy to repair or replace the cylinder. Each coating machine does not affect each other, and there are also a number of coating machines sharing a group of cylinders, which may be used in some larger coating workshops. It has the advantages of reducing the amount of gas cylinder, unified planning, unified layout, and the disadvantage is that the chance of gas leakage is increased because of the increase of the joint.
Each coating machine will interfere with each other, and the leakage of a coating machine may affect the quality of the other coating machines. In addition, when replacing the cylinder, it must be ensure that all the main units are not used.
6. Mechanical transmission part
The tool coating requires uniform thickness around, so there must be three rotations in the coating process to meet the requirements. That is, while the large workpiece table is required to rotate, the small workpiece table also rotates, and the workpiece itself can rotate at the same time. In mechanical design, the central part of the turntable is usually a large active gear, which is surrounded by some small star wheel, and then the fork is used to rotate the workpiece to rotate.
7. Heating and temperature measuring unit
When the mold coating process, to ensure the coating workpiece be heated uniformly is much more important than heating the decorative coating. Mold coating equipment generally has two heater, thermocouple temperature measurement and control. Due to the thermocouple fixture for different settings, the temperature readings cannot be the true temperature of the workpiece. To measure the true temperature of the workpiece, the surface thermometer (Surface Thermomeer) can be used. The principle of the thermometer is that when the thermometer is heated, the bottom of the spring will be heated to expand, so that the pointer to promote the positioning pointer rotation until the maximum temperature. When cooling, the spring shrinks and the pointer reversely rotates, but the positioning pointer stays at the highest temperature and the temperature of the pointer is read after the opening of the vacuum chamber door when the vacuum chamber is heated, the location of the surface thermometer has reached the highest temperature value.
8. Ionic evaporation or sputtering source
The evaporation source multi arc plating is generally circular, commonly known as round cake target, in recent years there have been many rectangular multi-arc target, but no obvious effect. The round cake target is mounted on the copper target seat (the cathode seat), both of which are connected by the rib. The target seat is equipped with a magnet, by moving the magnet back and forth, changing the magnetic field strength, adjustable arc spot moving speed and trajectory. In order to reduce the temperature of the target and the target holder, the cooling water should be continuously supplied to the target holder. In order to ensure the high conductivity and thermal conductivity between the target and the target holder, the tin (Sn) gasket can be added between the target and the target.
9. Water cooling system
In order to increase the ionization rate of the metal atoms, each cathode target is output at a large power and therefore needs to be sufficiently cooled. Many kinds of mold coating, the heating temperature is 400~500℃, therefore, on the vacuum chamber wall, the sealing surface cooling is also very important, so the cooling water is best used in the water chiller of about 18~20℃.
After the door were opened, in order to prevent the Low temperature vacuum chamber wall, cathode target and hot air contact precipitation of water , open the door in the first 10 minutes, the cooling system should switch to the state of hot water, hot water temperature is about 40~45℃.