JPS6349788A - Manufacture of liquid crystal panel - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method for manufacturing a liquid crystal display device, particularly a liquid crystal panel suitable for a matrix type liquid crystal panel having deep irregularities on the substrate surface.

As is well known in the art, a matrix type liquid crystal display device consists of a pair of substrates, one of which is a transparent insulating substrate, such as a glass plate, on which a scanning line pattern is formed using a transparent conductive film, and the other substrate is After forming the same signal line pattern on top and further forming a transparent insulating thin film layer to prevent short circuits, an alignment film is formed in a predetermined area by full printing, etc., and the alignment film is rubbed with a dry cloth. Orientation treatment such as so-called rubbing is performed. After that, place the pair of substrates facing each other and set the gap number μ.
A liquid crystal panel is completed by forming a space of m, filling the space with liquid crystal, and attaching a polarizing plate depending on the characteristics of the liquid crystal used.

In order to color a liquid crystal panel, it is common to arrange a colored layer of dyed gelatin on one substrate.

FIG. 5 is a perspective view showing the state immediately before the pair of glass plates 1 and 2 are pasted together with the sealing material 3. As mentioned earlier, there are scanning lines formed by a transparent conductive film on the whole surface of one of the glass plates 2. A group 4 is formed, and a signal line group 6 is similarly formed on the entire surface of the other glass plate 1. A pair of glass plates 1 and 2 are bonded together so that scanning lines 4 and signal lines 6 are approximately orthogonal to each other. The sealing material 3 has the function of forming a space to confine the liquid crystal and at the same time bonding the pair of glass plates 1.2. The notch 8 formed in the sealing material 3 is necessary to ensure a passage for the liquid crystal when the liquid crystal is injected, and is filled with a sealant (not shown) after the panel is formed. In the area where an image is displayed, an organic thin film, such as a polyimide-based CPIQ) resin, is selectively formed as an alignment film 7 in order to align the liquid crystal.

FIG. 7 shows a cross-sectional view of a colored liquid crystal panel cut parallel to the scanning line. 7 is the above-mentioned alignment film, and a space 8 made up of a pair of glass plates 1 and 2 and a sealing material 3 is filled with liquid crystal, and although not shown, in order to maintain the thickness of this space 8 at a predetermined value. The insulating material to be sprayed is a spacer, for example, a glass fiber or a plastic ball. Reference numeral 9 denotes a transparent insulating thin film, such as a silica film, to prevent the signal line 6 and the scanning line from being short-circuited by conductive foreign matter, and to avoid deterioration caused by direct current flowing through the liquid crystal.

1o is a colored layer formed by K when an organic thin film such as gelatin is colored with a dye, and the three primary colors R, G, and B having predetermined spectral characteristics are arranged according to the optical design of the color filter. It is advantageous to fill the gaps between adjacent colored layers 10 with a thin film layer 11 that is opaque to the light source, since an image with a high contrast ratio can be obtained. This is the so-called black or coma matrix treatment, but the thin film layer 11 may be made opaque by using a metal thin film such as chromium. It's okay,
There is considerable freedom in design.

As mentioned earlier, 12 is a polarizing plate, and when a liquid crystal 5KTN (twisted nematic) type one is used, two plates, upper and lower, are required. Electric signals are supplied to the scanning line 4 and signal line 6 by pressing a flexible film terminal coated with a conductive thin film onto the scanning electrode 4' on a glass plate extending from the sealing material 3 to the outer periphery. It is done by means (implementation) of

In recent years, so-called active matrix substrates, in which nonlinear elements such as TPTs (thin film transistors) and MIMs are built into the substrate as analog switches, have made it possible to arrange scanning lines and signal lines on the same substrate. The other substrate only needs to have a common transparent conductive film.

FIG. 8 shows a sectional view of a main part of the image area of a color liquid crystal panel which is a combination of an active matrix substrate 13 and a color filter 16 having a common transparent electrode 14, and 7 is an alignment film as in the conventional example. Although details are omitted, on the active matrix substrate 13, a pixel electrode 16 made of a transparent conductive film and a switching TPT (not shown) are formed at each intersection of a scanning line (not shown) and a signal line 6. , 17.
18 is a transparent insulating material such as Sio2 or 513N4.

In the active matrix substrate 13, many thin films are selectively deposited to form elements, so the surface of the substrate is extremely uneven, and it is not uncommon for the maximum step difference to exceed 1 μm.

Especially signal line 6. This tendency is stronger when An f is used for
In FIG. 8, the other parts are omitted and the step difference in the A1 layer 6 is emphasized.

Further, in FIG. 8, the thicknesses of the colored layer 10 are R and G.

The reason why they are formed differently in B is that it is a design measure to correct the optical path difference due to the wavelength of light passing through the liquid crystal and increase the contrast ratio, and the difference in thickness is solely due to the transmission anisotropy of the liquid crystal 8. Previous examples have shown that it is determined by Δn and is 0.4 to 0.8 μm (Japanese Patent Application Laid-open No. 60-1
No. 69823).

Problems to be Solved by the Invention As mentioned above, in a liquid crystal panel having a deep step on the surface of a substrate constituting a liquid crystal cell, it is necessary to make the coating thickness of the alignment film 7 uniform and to keep the rubbing state uniform in the alignment treatment. It is difficult to do so, resulting in uneven orientation.

Phenomena such as flicker occur and the quality of the image is poor, and the problem is that the image quality deteriorates.

The alignment film is generally made of polyimide resin with a film thickness of SOO~200
It consists of OA and a very thin coat.

Furthermore, as is clear from FIG. 5, the alignment film 7 is
must be located inside. This is because if the alignment film A straddles the sealing material 3, moisture from the outside air will pass through the alignment film 7 and enter during the liquid crystal display day, thereby degrading the liquid crystal. Therefore, offset printing technology is usually used as a means for selectively applying an alignment film. In offset printing, as shown in Fig. 9, the entire polyimide resin solution 21 of the alignment film material is dropped from the syringe 20, and
After stretching the resin liquid 24 to a predetermined thickness using the doctor roll 22 and the doctor roll 23 and transferring the resin liquid 24 to the rubber plate 26 on the main roll 26, the transport stage 27 is transferred to the main roll 2.
6, the substrate 2 on the transfer stage 27 is
8, the resin liquid 24 on the rubber plate 26 is applied.

In this way, in offset printing, many transfers are performed by adjusting suppression. Especially in the final transfer, the thickness is O*1 mI.
A rubber plate with a diameter of about The situation is such that the thickness accuracy is only about ±20 inches at best.

The present invention has been made in view of the above, and an object of the present invention is to provide a method of manufacturing a liquid crystal panel with good image quality using an alignment film coating method with high thickness accuracy.

Means for Solving the Interference Point In the present invention, the method for selectively applying an alignment film includes coating the entire surface of the alignment film, forming a selective photosensitive resin pattern using a photosensitive resin, and forming a photosensitive resin pattern using a photosensitive resin. This is achieved by selectively removing the alignment film used as a mask and removing the photosensitive resin pattern.

Effects According to the present invention, with the above-described configuration, first, the alignment film is coated on the entire surface, and a high accuracy of ±6 inches or less of the coating thickness is guaranteed.

Next, patterning of the positive photosensitive resin (resist) is carried out without any post-baking process. Subsequently, the alignment film is ashed using 02 plasma using the resist pattern as a mask. At the same time, the resist is also ashed, but the thickness of the resist is at least 5 times the coating thickness of the alignment film, approximately 1 μm.
If it is selected to be greater than or equal to m, the resist will only be thinned and there will be no risk of the alignment film disappearing. Finally, the resist is removed and selective coating of the alignment film is completed.

Note that if a positive resist is not subjected to a post-bake process, it is easy to dissolve and remove it using an organic solvent such as acetone or ethyl cellosolve, and it is also possible to dissolve and remove it by exposing the entire resist pattern to light and reproducing the image. .

Embodiment FIG. 1 is a perspective view showing a process flow of a method for forming an alignment film in a first embodiment of the present invention and states according to the progress of a substrate. First, a polyimide thin film 3o is applied to the entire surface of the substrate 1 by spin coating. Next, a heat treatment called curing is performed to volatilize the solvent in the polyimide resin and at the same time advance poly(polymerization) of the imide resin. The heat treatment temperature varies depending on the material and varies from 1500 to 450'C, and the material is selected depending on the configuration of the substrate.

Subsequently, a positive type resist 31 (for example, Silapray AZ-1400) is applied to the entire surface and prepainting is performed. It is sufficient that the coating thickness be at least 5 times the thickness of the alignment film, or about 1 μm or more. A photomask is required for selective exposure, but since the precision of the predetermined position of the alignment film is low, a mask alignment machine consisting of a combination of a stopper and a pressing plate is sufficient for mask alignment.

After exposure to ultraviolet rays, development is done using Silplay M.
A patterned positive resist 31 is formed on the polyimide film 3o by rinsing with IF-304 developer and pure water.
′ is obtained. After that, the substrate temperature in O2 plasma is 10
If the treatment is carried out at a temperature not exceeding 0°C, the exposed polyimide film will be ashed and the surface of the substrate 1 will be roughened. Since a positive resist that has not undergone post-baking can be easily dissolved away using an organic solvent such as acetone or ethyl cellosolve, it is possible to remove the resist without chemically altering the polyimide alignment film 30'. be.

Finally, curing is added to volatilize the moisture that the alignment film 30' may have received in the previous steps, thereby completing the selective application of the alignment film.

As described above, according to this example, by applying the alignment film by spin coating, even if there are deep steps on the substrate surface, a coating with very little variation in coating thickness can be obtained, and image quality such as uneven alignment and flicker can be obtained. Phenomena that lead to decline are significantly reduced.

2 to 4 show process flows of alignment film coating methods in second to fourth embodiments of the present invention, and relate to a method for processing a multi-sided substrate.

As in the first embodiment, the accuracy of the coating thickness of the alignment film is guaranteed, and since the alignment film is protected by a positive resist during cutting, it will not be damaged or contaminated by cutting liquid during cutting. The side effect of not having to worry about anything is also great. Especially the third one. In the fourth embodiment, since the substrate is double protected by the alignment film and the positive resist during cutting, the area outside where the alignment film is placed, that is, even the electrode terminal area, is protected, and the secondary effect is even greater. Become.

In the fifth embodiment shown in FIG. 5, the resist removal process in the first to fourth embodiments is not carried out using an organic solvent such as acetone or ethylene cellulose, but the positive resist is exposed again to ultraviolet rays. It is then removed using a developer. In this example, since there is little chemical damage to the organic materials present on the substrate, including the alignment film, it can be seen that it is particularly suitable for applying an alignment film to a color filter.

Effects of the Invention As described above, according to the present invention, even if there are deep steps on the substrate surface, the coating precision of the alignment film can be increased, and a remarkable effect can be obtained in suppressing alignment unevenness and flicker. Furthermore, damage and contamination of the substrate surface during cutting can be prevented at the same time, which has a great practical effect.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing a liquid crystal panel according to a first embodiment of the present invention, FIGS. The figure is a cross-sectional view of a main part of a liquid crystal panel composed of a substrate having deep irregularities, and FIG. 9 is a conceptual diagram of a method of applying an alignment film by offset printing. 1.13.27... Board, 2,16...
・Color filter, 3...Seal, 4...
...1Jil, 5...signal line, 7...
Alignment film, 8...Liquid crystal, 10...Colored layer, 11...Black matrix, 12...
...Polarizing plate, 14... Common transparent electrode, 21...
...Polyimide (PIQ) resin liquid, 26...
...Rubber version. Name of agent: Patent attorney Toshio Nakao and 1 other person1,
13-・-] [Insufficient 3l---y Letter υ Digit 1st Figure 2 Figure 3 Figure 4 Figure 5 Figure 5

Claims (8)

[Claims] (1) A step of applying an alignment film onto a substrate constituting a liquid crystal panel, a step of curing the alignment film, a step of applying a positive photosensitive resin onto the alignment film, and a step of applying the positive photosensitive resin to the alignment film. a step of prepaking the positive photosensitive resin, a step of patterning the positive photosensitive resin by selective exposure and development, and selectively ashing the alignment film by O_2 plasma treatment using the patterned positive photosensitive resin as a mask. 1. A method for manufacturing a liquid crystal panel, comprising: a step of removing the patterned positive photosensitive resin using an organic solvent to form an alignment film in a predetermined region. (2) The method for manufacturing a liquid crystal panel according to claim 1, characterized in that the patterned positive photosensitive resin is removed by full-surface exposure and reproduction. (3) a step of applying an alignment film on a substrate on which multiple substrates constituting a liquid crystal panel are attached, a step of curing the alignment film, and a step of applying a positive photosensitive resin on the alignment film; a step of prepaking the positive photosensitive resin;
a step of patterning the positive photosensitive resin by selective exposure and development; a step of selectively ashing the alignment film by O_2 plasma treatment using the patterned positive photosensitive resin as a mask; Manufacturing a liquid crystal panel comprising the steps of: cutting a multi-sided substrate; and removing the patterned positive photosensitive resin with an organic solvent to form an alignment film in a predetermined region. Method. (4) The method for manufacturing a liquid crystal panel according to claim 3, characterized in that the patterned positive photosensitive resin is removed by full-surface exposure and reproduction. (5) a step of applying an alignment film on a substrate on which multiple substrates constituting a liquid crystal panel are attached, a step of curing the alignment film, and a step of applying a positive photosensitive resin on the alignment film; a step of prepaking the positive photosensitive resin;
A step of cutting the multi-sided substrate, a step of patterning the positive photosensitive resin by selective exposure and development, and a step of performing the orientation by O_2 plasma treatment using the patterned positive photosensitive resin as a mask. A method for manufacturing a liquid crystal panel, comprising the steps of selectively ashing the film, and removing the patterned positive photosensitive resin with an organic solvent to form an alignment film in a predetermined region. . (6) The method for manufacturing a liquid crystal panel according to claim 5, characterized in that the patterned positive photosensitive resin is removed by full-surface exposure and reproduction. (7) a step of applying an alignment film on a substrate on which multiple substrates constituting a liquid crystal panel are attached, a step of curing the alignment film, and a step of applying a positive photosensitive resin on the alignment film; a step of prepaking the positive photosensitive resin;
a step of selectively exposing the positive photosensitive resin; a step of cutting the multi-faceted substrate; a step of patterning the positive photosensitive resin by development; and a step of patterning the positive photosensitive resin using the patterned positive photosensitive resin. selectively ashing the alignment film with O_2 plasma using a synthetic resin as a mask;
A method for manufacturing a liquid crystal panel, comprising the step of removing the patterned positive photosensitive resin using an organic solvent and forming an alignment film in a predetermined region. (8) The method for manufacturing a liquid crystal panel according to claim 7, characterized in that the patterned positive photosensitive resin is removed by full-surface exposure and reproduction.