Application of Tungsten Heater in Vacuum Evaporation Machine

The production raw materials of vacuum evaporation machine are inseparable from mineral resources, such as tungsten, molybdenum, rare earth, and other important strategic metals, and the machine is one of the products that China relies heavily on imports. The target material of the vacuum evaporation machine is often prepared with tungsten heaters, which could save energy as well as improve quality, and produce various terminal screens that are as thin as paper as well.

The main production materials for the screens of various electronic products such as computers and smart phones we use are organic light-emitting diodes (OLED), the most important part of the OLED production process is "steaming", which is extremely difficult. In addition to evaporation equipment is a key link in OLED production, manufacturers should also scientifically manage and integrate the entire production chain to ensure that each process is controllable and reliable.

the tungsten heater image

The vacuum evaporation machine is like the "heart" of the OLED panel manufacturing process, and is currently monopolized by Canon Tokki in the high-end market. According to industry insiders, the annual output of Canon Tokki's vacuum evaporation machines is usually between a few to a dozen. What's more worth mentioning is that the company can control the error of the organic light-emitting material evaporation onto the substrate within 5 microns (1 micron is equivalent to 1% of the diameter of the hair) to ensure that the prepared OLED screens have higher quality. Therefore, buying a Canon Tokki device is like getting an "entry ticket" for OLED panels.

The principle of the vacuum evaporation machine is to use various forms of thermal energy conversion methods to protect the coating material from evaporating and become gaseous particles (atoms, molecules, or groups of atoms) with certain energy under the pressure of 10E-3~10E-4 Pa. The vaporized gaseous particles are transported to the substrate in a collision-free linear motion and then condense on the substrate to form a coating.

In vacuum evaporation, gaseous particles are produced by the evaporation material in the evaporation source, and the heating of the evaporation source can be done by resistance method, high-frequency induction method, electron beam bombardment method, laser evaporation, or discharge method. However, regardless of the heating method, the material used as the evaporation source is required to have a high melting point, low vapor pressure, good thermochemical stability, and high mechanical strength, etc.

Tungsten has the advantages of high melting point and boiling point, 3410°C and 5927°C respectively, as well as extremely low vapor pressure, excellent chemical stability, high strength, and hardness, etc., so it is often used as a material of the evaporation source is the heater.

As a major producer of tungsten in the world, the metal reserves in China account for about 70% of the world's total reserves, and the production accounts for 80% of the world's total production. A large part of the resources consumed by the global industry every year comes from China. Although China does not have the ability to produce a vacuum evaporation machine currently, it could provide key production raw materials, such as tungsten materials as evaporation sources.