JPH07175055A - Method for manufacturing plastic liquid crystal display device - Google Patents

Abstract

PURPOSE:To improve the warpage of a plastic substrate by the internal stress of transparent conductive films by forming the transparent conductive films of the same film thickness on both surfaces of the plastic substrate. CONSTITUTION:The transparent conductive films 3 are formed at the same film thickness on both surfaces of the plastic substrate 1 in such a manner that the etching conditions for both surfaces of the plastic substrate 1 are the same and warpage is minimized. Etching liquids are simultaneously showered from both sides of the upper side and the lower side at the time of patterning by a wet etching method or the transparent conductive film 3 on the non- electrode surface side is removed simultaneously with formation of the electrode patterns 4. The film thickness of the transparent conductive film 3 is specified to be >=100nm in this case. This transparent conductive film 3 is preferably an indium tin oxide film. As a result, problem on the transportation defect and sucking defect due to the warpage of the plastic substrate 1 are solved and a non-defective rate is improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a plastic liquid crystal display device, and more particularly, to prevent warpage of a substrate until an electrode pattern is formed and to prevent conveyance failure and suction failure due to the warp of the substrate. The present invention relates to a method of manufacturing a plastic liquid crystal display device that can be manufactured.

[0002]

2. Description of the Related Art In a plastic liquid crystal display device, an indium tin oxide film (hereinafter abbreviated as ITO) is formed only on an electrode pattern forming surface of a plastic substrate as well as a glass substrate.
A transparent conductive film such as is formed by a sputtering method or a vacuum deposition method. Then, the resistance of the transparent conductive film is required to be reduced due to the demand for a larger panel, and the resistance value is reduced by increasing the film thickness of the transparent conductive film.

However, as the thickness of the transparent conductive film increases,
The warpage of plastic substrates is also increasing. As a countermeasure against this warpage, there is a method described in JP-A-5-66411 in which one of the coat layers of the substrate is thickened and an organic film or a transparent conductive film is formed on the non-electrode surface side.

[0004]

As the film thickness of the transparent conductive film increases, the internal stress of the transparent conductive film also increases the warpage of the plastic substrate. Problems caused by this increase in warpage include defective conveyance in the process to the exposure machine including resist coating, adsorption failure to the base of the exposure machine, poor conveyance in the development process, etc. Was causing the lowering.

The relationship between substrate warpage and various defects is 30
When a 0 mm × 300 mm plastic substrate was allowed to stand on a flat surface and the substrate was warped by 2 mm or more from the bottom surface, the incidence of defects rapidly increased.

[0006]

[Table 1]

In the method of forming the coating layer on the non-electrode surface side thicker than the coating layer on the electrode surface side, which is disclosed in Japanese Patent Laid-Open No. 5-66411, reverse warpage occurs after patterning, resulting in poor transport in subsequent steps. Adsorption failure etc. had occurred. In particular, many adsorption defects occurred. Similarly, JP-A-5-66411.
In the method of forming an organic film or a transparent conductive film on the non-electrode surface side of the publication, reverse warping occurs after patterning, and thus a new step for removing the film on the non-electrode surface side is required. In addition, conveyance failure and the like occur between the patterning and the removal of the organic film or the transparent conductive film on the non-electrode surface side, which does not lead to a large cost reduction.

[0008]

[Means for Solving the Problems] In order to improve the non-defective rate of plastic liquid crystal display devices, that is, to reduce the cost, by solving problems such as conveyance defects and suction defects due to warpage of plastic substrates, In the manufacturing method, the etching conditions on both sides of the plastic substrate are the same, and the transparent conductive film is formed to have the same film thickness on both sides of the plastic substrate so that the warpage is minimized. Shower the etching solution from both sides of
The feature of the present invention is that the substrate is warped by removing the transparent conductive film on the non-electrode surface side at the same time as forming the electrode pattern by batch processing by the dipping method.

[0009]

[Function] By setting the same etching conditions on both sides of the plastic substrate and forming the transparent conductive films of the same thickness on both sides of the plastic substrate so that the warpage is minimized,
The warp of the plastic substrate due to the internal stress of the transparent conductive film is significantly improved. Further, when patterning by wet etching, by removing the transparent conductive film on the non-electrode surface side at the same time as forming the electrode pattern, it is possible to prevent the plastic substrate from being warped, and the transparent conductive film on the non-electrode surface side is formed. The step of removing can be omitted. As a result, it is possible to improve the conveyance failure and the suction failure and improve the non-defective rate.

[0010]

【Example】

Example 1 As shown in FIG. 1A, a gas barrier layer,
On both surfaces of the epoxy-based plastic substrate 1 having a hard coat layer of 300 mm × 300 mm and a plate thickness of 0.4 mm,
ITO2 and ITO3 having a thickness of 200 nm were formed by a vacuum deposition method. The warpage of the plastic substrate at this time is 0.5
It was less than mm. This plastic substrate was washed with a shower, a resist was applied only to the electrode pattern forming surface with a roll coater, and then exposure was performed with an arbitrary pattern. Next, a 0.6 wt% NaOH solution was showered and developed, and a 3N HBr solution was showered from both upper and lower sides for etching. At this time, as shown in FIG. 1B, the electrode pattern 4 is formed on the electrode pattern forming surface of the plastic substrate 1 and, at the same time, the ITO 3 on the non-electrode surface side is removed to prevent the plastic substrate from being warped. I was able to. Next, a 2 wt% NaOH solution was showered to remove the resist, and the patterning process was completed. The non-defective rate in the patterning process at this time is 9
It was 9%. The warp of the plastic substrate after the formation of the electrode pattern 4 becomes slightly larger due to the removal of the ITO 3 on the non-electrode surface side, but the warp is 1 mm or less, and in the subsequent steps, problems such as conveyance failure and suction failure do not occur. It was

(Example 2) Example 2 was carried out in the same manner as in Example 1 except that the development and etching were carried out by a batch process by a dipping method. For batch processing, a cassette for curving and holding a plastic substrate described in Japanese Patent Application No. 4-291142 devised by the present inventors was used. The non-defective rate in the patterning step at this time was 98%. The warp of the plastic substrate after the formation of the electrode pattern 4 becomes slightly larger due to the removal of the ITO 3 on the non-electrode surface side, but the warp is 1 mm or less, and in the subsequent steps, problems such as conveyance failure and suction failure do not occur. It was

(Comparative Example 1) As shown in FIG. 2 (a), one side of the plastic substrate 5 was coated with ITO 6 at 70 nm and 100 nm.
nm, 160 nm, and 200 nm are formed, and a shower at the time of etching is performed only from the upper side,
The same procedure as in Example 1 was performed except that the patterning process was performed. Table 1 shows the warpage of the plastic substrate before forming the electrode pattern 7 and the non-defective rate in the patterning process. The warp of the plastic substrate after forming the electrode pattern 7 was 1 mm or less, and in the subsequent steps, problems such as conveyance failure and suction failure did not occur. The results are shown in Table 1.

(Comparative Example 2) The procedure of Example 1 was repeated, except that the shower during etching was performed only from the upper side.
The non-defective rate in the patterning step at this time was 70%. As shown in FIG. 3B, the warp of the plastic substrate after the electrode pattern 11 is formed is the ITO on the non-electrode surface side.
Since No. 10 was not removed, reverse warpage of 2.7 mm to 3.1 mm occurred, which often resulted in poor conveyance in the resist stripping process, which reduced the yield rate in the patterning process.

Example 1, Example 2, Comparative Example 1, Comparative Example 2
Table 2 shows the warpage of the plastic substrate before and after the electrode pattern formation and the non-defective rate in the patterning process. The material of the plastic substrate, the thickness of the plastic substrate, the laminated structure of the gas barrier layer, the method of forming the transparent conductive film, the material of the transparent conductive film, the film thickness of the transparent conductive film, the developing solution, the etching solution, and the resist stripping solution are It is not limited to the examples.

[0015]

[Table 2]

[0016]

EFFECTS OF THE INVENTION The same etching conditions are applied to both sides of a plastic substrate, and transparent conductive films of the same thickness are formed on both sides of the plastic substrate so that warpage is minimized. Substrate warpage is greatly improved, and conveyance defects and adsorption defects during the etching process can be improved. Further, when patterning by wet etching, by removing the transparent conductive film on the non-electrode surface side at the same time as forming the electrode pattern, it is possible to prevent the plastic substrate from being warped, and the transparent conductive film on the non-electrode surface side is formed. The step of removing can be omitted.
As a result, the rate of non-defective products can be significantly improved, leading to a large cost reduction.

[Brief description of drawings]

FIG. 1 is a schematic view of a plastic substrate in a patterning process of a plastic liquid crystal display device according to the present invention.

FIG. 2 is a schematic view of a plastic substrate in a patterning process of a plastic liquid crystal display element according to a conventional example described in Comparative Example 1.

FIG. 3 is a schematic view of a plastic substrate in a patterning process of a plastic liquid crystal display element according to a conventional example described in Comparative Example 2.

[Explanation of symbols]

 1, 5, 8 Plastic substrate 2, 6, 9 Transparent conductive film (electrode surface side) 3 Transparent conductive film (non-electrode surface side) 4, 7, 11 Electrode pattern 10 Transparent conductive film or organic film (non-electrode surface side)

Claims (3)

[Claims] 1. A wet etching method is used to pattern a plastic substrate on which a transparent conductive film is directly formed, or a laminated plastic substrate on which a transparent conductive film is formed via a gas barrier layer, a hard coat layer, an undercoat layer and the like. In the method of manufacturing a plastic liquid crystal display element, a transparent conductive film having the same thickness is formed on both surfaces of the plastic substrate, and at the time of patterning by the wet etching method, the transparent conductive film on the non-electrode surface side is peeled off at the same time when the electrode pattern is formed. A method for manufacturing a plastic liquid crystal display device, comprising: 2. The method for producing a plastic liquid crystal display device according to claim 1, wherein the transparent conductive film has a film thickness of 100 nm or more. 3. The method for manufacturing a plastic liquid crystal display device according to claim 1, wherein the transparent conductive film is an indium tin oxide film.