First, the working principle of ultraviolet light cleaning:
The light cleaning technology utilizes the photosensitive oxidation of organic compounds to remove organic substances adhering to the surface of the material, and the surface of the material after light cleaning can achieve "atomic cleanliness". More specifically: UV light sources emit light at wavelengths of 185 nm and 254 nm, which have high energy. When these photons act on the surface of the object being cleaned, most of the hydrocarbons have a strong absorption of ultraviolet light at 185 nm wavelength. The ability to decompose into ions, free atoms, excited molecules and neutrons after absorbing the energy of ultraviolet light at a wavelength of 185 nm is called photo-sensitization. Oxygen molecules in the air also produce ozone and atomic oxygen after absorbing ultraviolet light at a wavelength of 185 nm. Ozone also has a strong absorption of ultraviolet light at a wavelength of 254 nm, which is decomposed into atomic oxygen and oxygen. Among them, atomic oxygen is extremely active. Under its action, carbon and hydrocarbon decomposition products on the surface of the object can be converted into volatile gases: carbon dioxide and water vapor, etc., which completely remove the adhesion to the surface of the object. Carbon and organic pollutants.
When cleaning, the substrate is made to be hygroscopic. The glass substrate is conveyed by a roller, and the low-pressure mercury lamp of the upper device generates ultraviolet irradiation. The more ultraviolet energy accumulated in the glass substrate, the smaller the surface water contact, and the inverse relationship.
In the general STN-LCD manufacturing process, the required glass substrate has an accumulated ultraviolet energy of 300 nj/cm 2 (253.7 nm) or more. In the process of producing color STN-LCD and color filter, the required glass substrate has an accumulated ultraviolet energy of 600 nj/cm 2 (253.7 nm). In the TFT-LCD manufacturing process, in addition to the low-pressure mercury lamp to produce ozone cleaning glass, the current mainstream of the process is the use of Excimer Lamp, its high reaction property of 172nm wavelength ultraviolet light is better for glass cleaning efficiency.
Second, the characteristics of light cleaning:
1. It is a squatting method that can be carried out in the air and does not have to be dried after washing.
2, can completely remove carbon and organic pollutants on the surface of the object.
3, no solvent evaporation and disposal of waste solvents.
4. Guarantee high reliability and high yield of products.
5. The uniformity of the surface cleaning treatment of the product is consistent.
6. Since light cleaning removes carbon and organic compounds on the surface of the object through photosensitivity and oxidation reaction, the surface which is prone to oxidation is not suitable for light cleaning. It is only suitable for surface dirt cleaning, unsuitable for dirt, and inorganic dirt cleaning. .
Third, the application range of light cleaning technology:
The light cleaning method is most suitable in the production processes of liquid crystal display devices, semiconductor silicon wafers, integrated circuits, high-precision printed circuit boards, optical devices, quartz crystals, sealing technology, and metal materials with oxide films.
Main materials: ITO glass, optical glass, chrome plate, mask plate, polished quartz crystal, silicon wafer and metal with oxide film for precision cleaning.
It can remove dirt: organic dirt, human sebum, cosmetic oils, resin additives and polyimide, paraffin, rosin, lubricating oil, residual photoresist and the like.
The UV light source has the characteristics of UV modification (UV surface quality change) in the LCD process. Currently, in the production process of the liquid crystal display STN, it is mainly used in the film processing technology, and the improvement of the adhesion between the film and the film is Very effective, such as ITO film and photosensitive film layer, TOP coating and PI coating. In addition, the research department can also be used for UV-modified plastic material products for nanotechnology research. The product undergoes chemical reaction by UV light irradiation to change the surface properties of the product. In the manufacturing process of STN-LCD, color filter and OLED, some process equipments are quite similar, the difference is the manufacturing process requirements. With the refinement of the line and the color ratio of the products, the LCD industry's requirements for the manufacturing process are constantly improving, and there is a demand for "workers must do their best, and they must first sharpen their tools." In order to improve the quality and efficiency of production.
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