The demand for photosensitive and corrosion-resist

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Requirements for photosensitive and corrosion-resistant ink in LCD graphic manufacturing (Part 2)

5. Exposure and special exposure equipment:

5.1 selection of light source:

1) the light energy emitted by ultraviolet light is used by photoinitiators, and the emitted spectrum should match the spectrum of initiators. Now most halogen lamps are used, and the light-emitting principle takes the high-pressure mercury lamp as an example: the mercury and additives in the vacuum tube evaporate under high pressure to form a luminous body. The emitted spectrum can excite the initiator and photoreceptor in the ink, thus forming the cross-linking of the ink layer. High pressure mercury lamps are commonly used

2) the efficiency of converting electric energy into ultraviolet light energy is high, but the calorific value is small

3) higher intensity of light energy application. If the intensity is too low, the generation of free radicals is too slow, and oxygen polymerization is seriously inhibited, which will affect the imaging quality

5.2 matching and selection of spectral peak:

1) light source: in the technical data of the ink supplier, this marking has no impact on the sample, and the spectral value of the exposure of the photosensitive anti-corrosion ink is not provided. However, the spectral range of all halogen lamps and high-pressure mercury lamps is suitable for the exposure of this ink, only the difference in intensity

2) the exposure table shall be made of high-quality polyester film with a thickness of 0.175mm. There shall be no scratches and scratches. The UV transmittance is excellent. When the spectrum is nm, the transmittance is more than 85%

in the early 1970s, the polyester used in the stage of the exposure machine produced in the United States was replaced with convex concave surface. Its advantages are strong ultraviolet transmission, good air conductivity, fast vacuum absorption speed and no dead angle in vacuum pumping. Therefore, it does not need a scraper or a self-made tool to drive the air, and the negative film will not move. It is particularly prominent in the manufacturing of LCD thin wire. It is reported that this material has been available in China. It should be noted that the convex concave polyester film is processed with a special die during drawing. The convex surface and bottom surface have a very high finish. Therefore, it must not be confused with the pitted or wool polyester film in purchase and use

3) reflector and parallel light: strictly speaking, all the light sources we use are point light sources. How to obtain parallel light or minimize the energy difference of the light source on the effective parts of the table is the main indicator to measure the level and performance of the exposure machine. This indicator mainly depends on the design and manufacturing level of the reflector. The reflectors are oval, and the drawings of reflectors from many manufacturers are confidential. This is because it is difficult to obtain the same energy as the central part in order to obtain the directional light, especially in the edge position where the table production and construction process seriously endanger people's health. The key is to see who can minimize the energy difference. Therefore, after the geometric size of the hood is determined, it is how to make the light absorbed by the surface of the reflector reflect to the table top to the greatest extent. Generally, the surface is treated with concave and convex surface, and then the surface is electropolished or chemically polished to make the surface reach or close to the mirror level. The reflectors are all made of aluminum magnesium alloy because aluminum is the only reflective material that can reflect nmuv light. The surface is provided with a protective layer. 75% of the UV light of the excellent reflector is reflected to the surface, and the remaining 25% of the energy has been directly radiated to the surface. The light intensity at the center and edge shall not exceed 15% error

4) control of light energy and exposure time: the ideal exposure machine should have an energy impact test machine, and the swing rod of the machine should not be aligned with the vertical mark display, while the time control accuracy display should be within 0 25s is particularly important in the graphic manufacturing of ITO layer of LCD. The accuracy of light energy and exposure time can eliminate overexposure and insufficient exposure, which is an important part of overall quality control

5.3 measurement of light energy:

1) application of UV photometer: in order to ensure accurate exposure energy, UV photometer and gradient ruler are mostly used as measurement tools during exposure, and the exposure intensity is measured with UV photometer

measurement method: put the probe of the UV photometer under the film of the drying plate rack with the probe face up. Different data of illumination can be measured by placing the probe at different positions. Generally, at least 5 points shall be measured, i.e. one point in the middle and one point in each corner, to see whether the light intensity of each part is consistent, so as to pay attention to adjustment during operation. UV photometer is a kind of measuring tool, which will produce errors after use for a period of time. In order to maintain its accuracy, it shall be regularly sent to the National Metrology Department for identification

measurement of exposure intensity and calculation of energy: first adjust the UV photometer to position 0, then put the probe into the sun rack and push it into the exposure area. After 5S, observe. The reading data is the light intensity 1. Unit of measurement: mw/cm2

2) light energy: e=it

i= light intensity mw/cm2, e= light energy mj/cm2, t= time (s)

some automatic UV photometers do not need to calculate, and the exposure energy can be automatically displayed as the exposure time is increased or decreased

3) application of gradient ruler: the gradient ruler is also a tool used to measure exposure data. It is used to expose and develop the sample, and finally read the reserved number of cells (Note: the accuracy can only be achieved when the concentration, temperature and transmission speed of each developer are consistent during measurement). There are three gradients: grade 17, grade 21 and grade 25. Currently, level 21 is mostly used. The light transmittance of two adjacent grids of the 21 grade light gradient ruler is 2 =1.414. That is, each additional grid needs to increase the exposure by 1.414 times. When many factories use the 21 grid gradient ruler, they always add and subtract the time according to the first exposure display grid number according to the usual experience until the required grid number is reached. This not only costs a lot of man hours, but is sometimes not very accurate. Therefore, a coefficient table is made according to the multiple relationship of light transmittance between two adjacent grids

21 grade optical ladder base coefficient comparison

21 grade optical ladder progression 21 grade optical ladder coefficient 21 grade optical ladder progression 21 grade optical ladder coefficient

1.414 922.590

2.999 1031.942


4 3.9971263.866


6 7.99014127.693

7 11.29815180.557

8 15.976

obtain the specified series (the best Series) The required exposure time can be calculated as follows (when the light source spring is fixed)

4) calculation of exposure time:

a. increase the number of stages: select the exposure factor according to the required number of stages and multiply the exposure time of the original measured number of stages to be the exposure time of the required number of stages

for example, if the exposure time is 16S and the normal development (temperature, concentration and time) is measured as grade 6, but it is recommended as grade 8, two more grades are required. It is found that the coefficient of level 2 is 1.999, so the exposure time of level 8 is 16S × 1.999=31 is 31s

b. reduce the number of stages: select the number of stages to be reduced as required, and divide it by the exposure time of the original measured number of stages, which is the exposure time you need

for example, the exposure time of 40s is measured to be 13 levels, but it is recommended to be 8 levels. According to the specified level, 5 levels need to be reduced. The coefficient of 5 levels is found to be 5.651, so the exposure time to obtain 8 levels should be 40s ÷ 5.651=7s

source: China polymer

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