JP3652486B2 - Color filter substrate and method for manufacturing the color filter substrate - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to a method for manufacturing a color filter substrate used in a color liquid crystal display device. In particular, the present invention relates to a method for manufacturing a color filter substrate suitable for a plastic film substrate having excellent portability.
[0002]
[Prior art]
Liquid crystal display devices have come to be used in various fields, and the CRT as an information display device has become a momentum. In particular, devices that require portability are adopted in many devices because of their small size, light weight, and low power consumption. Among them, most of them use glass as a substrate, but liquid crystal display devices using a plastic film have come to be used for portable devices such as mobile phones and electronic notebooks. The plastic film has a thickness of about 0.1 to 0.3 mm and is light in weight, so it is most suitable for portable devices. However, it is difficult to form a color filter due to the fact that fine patterning is difficult on a film substrate and the dimensions of the substrate slightly change depending on the environment such as temperature and humidity. is there. On the other hand, although a color display method that does not use a color filter has been proposed, the number of colors that can be displayed is limited, and the display color is not vivid. Further, in this method, since it is necessary to strictly control the distance between two substrates (cell gap), the plastic film liquid crystal display device in which it is difficult to control the distance between the substrates has not yet been put into practical use.
Various methods such as a dyeing method, a pigment dispersion method, an electrodeposition method, a micelle electrolysis method, and a printing method have been proposed as a method for producing a color filter for liquid crystal. In the dyeing method, the pigment dispersion method, the printing method, etc., in the pattern formation of red (R), green (G), blue (B), and black (BK), each position is accurately aligned with other patterns. There is a need. For example, a black pattern is first formed, and red, green, and blue patterns are formed while precisely aligning the black pattern. Further, it is necessary to align the color filter pattern and the liquid crystal driving electrode. The alignment accuracy depends on the material, size, manufacturing apparatus, and the like of the substrate to be used, but when a glass substrate is used, alignment in units of microns is possible. On the other hand, the plastic film substrate undergoes a large dimensional change compared to the glass substrate. Naturally, the thermal history causes a dimensional change of ± 0.1% depending on the temperature and humidity where the film is placed. For this reason, it is very difficult to perform precise alignment. In order to produce a color filter on a plastic film substrate, a manufacturing process that does not require precise alignment or reduces the number of steps that require precise alignment is required.
[0003]
Among the color filter manufacturing methods described above, in the micellar electrolysis method (JP-A-2-24603, JP-A-2-146001), a color filter layer is selectively formed on the transparent conductive film pattern provided on the substrate. There is no misalignment between colors. Further, it has been proposed that the color filter layer is made of a conductive material, or the electrode for forming a filter is also used as a liquid crystal driving electrode by mixing a conductive material in the color filter layer (Japanese Patent Laid-Open No. 6-34809). ).
However, when the color filter layer is made conductive, when forming a color filter composed of a plurality of colors (for example, three colors of R, G, and B), electrodes must be selectively connected for each color. A color liquid crystal display device generally has an electrode pitch of 100 μm or less, and it is difficult to directly probe one electrode and connect it to an external circuit. For this reason, in Japanese Patent Laid-Open No. 3-102302 , an electrode extraction window that can selectively extract electrodes corresponding to R, G, and B colors is formed of a photosensitive resin, and then connected to an external circuit with a conductive paste. Is going. However, when an attempt was made to form a color filter on a plastic film substrate by this method, problems such as poor contact between the conductive paste and the electrode material due to changes in the substrate dimensions occurred.
On the other hand, JP-A-2-175977 and JP-A-3-4202 propose a method of cutting the colored electrode by etching without using an electrode extraction window, but both methods complicate the manufacturing process. It is difficult to apply to plastic film substrates.
[0004]
[Problems to be solved by the invention]
An object of the present invention is to provide a method for forming a conductive color filter on a plastic film substrate by an electrochemical method, and a plastic color liquid crystal display device using the film substrate on which the conductive color filter is mounted.
In particular, the present invention is to provide a conductive color filter and a method for manufacturing the same, in which the conduction of the contact hole portion is further ensured, and the failure at the time of filter formation accompanying the connection failure is greatly reduced.
[0005]
[Means for Solving the Problems]
FIG. 2 schematically shows a cross-sectional view of a conventional contact hole portion. In such an electrical connection of the conventional example, the connection becomes unstable, and there is a case where a color filter is not partially formed due to poor contact. This phenomenon was particularly remarkable when a resin film was used as the substrate 1.
As a result of various studies to improve such a phenomenon, the present inventors have found that the cause of the contact failure is an adhesive force between the conductive material and the electrode, and in particular in the case of a flexible resin substrate, the deformation of the substrate. As a result, the conductive material in the contact hole part floated, and it was concluded that sufficient contact between the conductive material and the electrode could not be obtained. Furthermore, as a result of investigations to improve this point, the present inventors have found that such a problem can be solved by providing a structure that increases the contact area with the conductive material in the contact hole portion, resulting in the present invention. It was.
[0006]
That is, according to the present invention, a colored component is deposited on a selected electrode of a patterned electrode on a substrate, a contact hole is formed on the colored electrode with an insulating material, and the contact hole A color filter substrate configured by connecting an electrode and an external power source through a conductive material, wherein the contact hole portion has a structure for increasing the contact area with the conductive material, and the color filter By providing a method for manufacturing a substrate, the problems related to the color filter substrate could be solved.
[0007]
In the color filter substrate of the present invention, for example, a specific electrode of a patterned electrode on the substrate has a contact hole for connecting the electrode and an external power source through a conductive material in a part on the electrode by an insulating material. A patterned electrode substrate that is formed and provided with a structure that increases the contact area with the conductive material in the contact hole portion is immersed in an electrolytic solution containing a coloring component, and the selected electrode is energized to supply the coloring component to the electrode. It can be manufactured by depositing on it.
[0008]
Hereinafter, a color filter substrate of the present invention and a method for producing the color filter substrate will be described in detail with reference to the drawings.
FIG. 1 is a schematic view of a substrate immersed in an electrolytic solution.
1 is an insulating substrate made of glass or synthetic resin, 21 to 23 are electrodes provided on the substrate, and for example, 21 is blue, 22 is green, and 23 is red. Provided. Reference numeral 3 denotes an insulating film in which a contact hole 4 is formed. Reference numeral 5 is a conductive material, and 52 and 53 are connecting portions to an external power supply circuit. A specific selected electrode group is obtained by, for example, immersing the substrate below the line indicated by A in an electrolyte containing a pigment and applying a voltage from an external circuit to an electrode having a contact hole through a conductive material. A color filter is formed only on the surface. For example, a blue filter is immersed in a red electrolyte by dipping in a blue electrolyte and energizing a blue filter on 21 electrodes, and a green filter is immersed in a green electrolyte and energizing in 22 electrodes. The red filter can be formed in 23 by energizing.
[0009]
FIG. 3 shows a configuration example of another color filter substrate of the present invention. In this example, a reverse taper structure as shown in FIG. 3 is provided on the wall surface of the contact hole to prevent the conductive material from floating in the contact hole. The method of forming the reverse tapered structure is not particularly limited, but for example, a positive photoresist that is solubilized by exposure is applied on the pattern substrate, and the pattern is exposed from the back surface, thereby forming the reverse tapered shape as shown in FIG. A contact hole having a wall surface is formed. Alternatively, a reverse-tapered cross section can also be obtained by exposing from the upper surface using a negative photoresist that is crosslinked and insoluble by exposure. In this case, the taper angle is preferably in the range of 10 ° to 45 °.
[0010]
FIG. 4 shows a configuration example of another color filter substrate of the present invention.
In this example, by providing the protrusion 7 in the contact hole, the adhesive force of the conductive material is improved, the conductive material is flattened, and the stress applied to the contact hole portion is dispersed.
The height of the protrusion 7 is preferably 10% to 120% of the insulating film thickness, and more preferably 50% to 100%. For the horizontal dimension of the contact hole, the width of the protrusion is preferably in the range of 5% to 90%. The number of protrusions is not limited to one for the contact hole, and a plurality of protrusions can be provided. In this case, the adhesive strength is further improved, which is preferable.
The protrusion may be made of the same material as or different from the insulating film, but it is preferable that the protrusion is made of the same material because the process is simplified. In addition, in the thing of this example, the adhesive force of a conduction | electrical_connection material can further be heightened by providing the reverse taper-shaped wall surface structure and the projection part 7 like FIG. The protrusions can be formed on the electrode as shown in FIGS. 4 and 5, but can also be provided on the lower part of the electrode as shown in FIG. With such a structure, the conductive material can be formed so as to be nearly flat or swell with respect to the periphery. With such a structure, the conductive material can be made difficult to lift from the electrode when the conductive material is cured, so that a more reliable connection can be ensured. In addition, this example has an advantage that the conductive area can be increased as compared with the case where the protrusion is formed using an insulator, which is preferable. In order to realize such a structure, specifically, the protrusion 9 may be formed using a photoresist or the like before the electrode is formed. Also, a plurality of such raised portions can be provided.
[0011]
FIGS. 6A and 6B show a configuration example of another color filter substrate of the present invention.
In this example, a more reliable contact is obtained by using a plurality of contact holes, one for each electrode, and the figure shows the case where the number of contact holes is four. . The area where the contact hole is open is the same as in FIG. 1, but the area is divided into four contact holes each having a size of 8 μm × 15 μm.
Here, FIG. 6A is a sectional view, and FIG. 6B is a plan view. By adopting such a plurality of contact holes, even if the contact of one contact hole becomes defective, electrical connection is ensured by the remaining contact hole, so that uniform filter formation can be performed. it can. The number of contact holes is not particularly limited. However, if the contact hole is too small, contact failure tends to occur. Therefore, the diameter of the opening is about 5 μm, which is the lower limit of the size. Further, when the number is increased, the area of the contact portion is increased as a result, and the effective area of the substrate is narrowed. Therefore, it is necessary to set an appropriate number. The number per electrode is preferably in the range of 2 to 20.
[0012]
FIGS. 7A and 7B show a configuration example of another color filter substrate of the present invention.
In this example, the adhesive strength is improved by providing a recess 8 below the contact hole. The recess 8 has a structure formed by an electrode pattern. Moreover, as a structure which provides the recessed part 8, the structure which provides the layer which has another recessed part in the electrode lower part is mentioned. The former structure is advantageous because it allows a large electrode area to be contacted, and the latter structure is advantageous in that it can be formed simultaneously with the patterning of the electrodes and thus does not involve an increase in the number of processes.
The lower limit of the size of the recess depends on the accuracy of the method of forming the recess, and the upper limit is determined by the size of the contact hole. It is preferably 1 μm or more, and preferably 70% or less of the size of the contact hole. The depth of the recess is preferably 0.05 μm to 5 μm, and more preferably 0.1 μm to 2 μm.
[0013]
As a substrate that can be used in the present invention, glass, a synthetic resin sheet, a synthetic resin film, or the like can be used. In particular, with synthetic resin sheets and synthetic resin films, there are deformations in the substrate due to handling in the manufacturing process, immersion in the electrolyte, and changes in temperature and humidity. Since a color filter free from defects can be provided by application, a synthetic resin sheet or a synthetic resin film is a substrate in which the present invention is particularly effective.
[0014]
Any insulating film can be used as long as it has insulating properties. However, a film having flexibility is preferable for use in a film, and an organic polymer film is preferably used. Since this insulating film needs to form a contact hole pattern, a photoresist material having photosensitivity and easy pattern formation is particularly preferably used.
[0015]
The lower limit of the thickness of the insulating film is a thickness at which insulation failure due to pinholes or the like does not occur, and generally the lower limit is about 0.2 μm. If it is too thick, poor conduction tends to occur, but the upper limit film thickness is determined by many factors such as the size and shape of the contact hole, the material of the conductive material, and the film thickness. In general, the thickness is preferably 20 μm or less, and is preferably 5 μm or less in consideration of the ease of film formation. In addition, the insulating film, protrusions, and irregularities in the present invention can be formed using a photoresist material. In this case, a black photoresist material is particularly preferable because a black mask can be simultaneously formed between the filters depending on the design of the mask.
[0016]
As the conductive material, a material capable of pattern formation as shown in FIG. 1 is required. For example, a metal film can be formed by vapor deposition or the like, and a pattern can be formed by photolithography. However, industrially, a method of forming a conductive paste in a pattern by printing or a dispenser is simple and advantageous. In particular, when a resin film is used as the substrate, the hardness of the conductive paste after curing affects the connection reliability. Therefore, a material having flexibility such as urethane and silicone and following the deformation of the substrate is particularly preferably used. By using the above-described contact hole shape and a flexible conductive paste in combination, it is possible to provide a highly reliable manufacturing method for the connection portion.
In addition, the color filter manufactured according to the present invention has high uniformity with no density unevenness due to poor conduction.
Therefore, a liquid crystal display device manufactured using this filter has a feature that it has excellent uniformity because of the small density unevenness of the filter.
[0017]
Next, this invention is demonstrated based on an Example.
In the following examples, unless otherwise noted, the substrate is a polyethersulfone substrate, the electrode material is ITO, the conductive material is an acrylic silver paste, and the insulating film is a positive photoresist (OFPR) (Tokyo). And a film thickness of 1.5 μm. The thickness of the conductive material was 0.4 mm, and the coating width was 1 mm. The contact hole was 20 μm × 40 μm.
The electrodes had a stripe shape with a width of 100 μm and a pitch of 110 μm, the electrode length was 150 mm, and the number of stripes was 1920. The connection of the electrodes was conducted every two lines as shown in FIG.
[0018]
Example 1
A reverse taper structure as shown in FIG. 3 was provided on the wall surface of the contact hole. The taper angle was about 20 °. On this, a thermosetting acrylic silver paste was applied using a dispenser and baked to cure the resin. This substrate was immersed in an aqueous dispersion containing conductive fine particles composed of blue pigment and tin oxide, an electrolyte, and a surfactant. The pigment and conductive fine particles were micellized with the surfactant, and the electrode was energized. In the case of this electrolytic solution, the surfactant is oxidized by the electrode reaction, the micelle is broken, and the pigment and the conductive fine particles are deposited on the electrode (film thickness: 1.5 μm). Then, the excess pigment was washed with water. After drying at 100 ° C., it was immersed in an electrolytic solution containing a green pigment, and other electrode groups were energized. By repeating the same operation, blue, green and red filters were formed. The filter thus produced had no defects and excellent uniformity.
[0019]
Example 2
In Example 1, the tapered structure of the insulating film was eliminated, and two 5 μm × 10 μm protrusions were formed by photoresist simultaneously with the formation of the insulating film pattern. With such a contact hole shape, the same filter formation as in Example 1 was performed. The filter thus produced had no defects and excellent uniformity.
[0020]
Example 3
In Example 2, the reverse taper structure similar to that in Example 1 was provided on both the protrusion and the insulating film. The filter thus produced had no defects and was even more uniform.
[0021]
Example 4
As shown in FIG. 8, a convex part having a size of 20 μm × 10 μm and a height of 1 μm was provided on the substrate by a black photoresist, and then ITO was formed. A black photoresist is also provided between the filters and serves as a black mask. The filter was produced in the same manner as in Example 1 without the reverse taper. The filter thus produced was free from defects and the uniformity was even better than that of Example 2.
[0022]
Example 5
As shown in FIG. 7, by patterning a 0.15 μm thick ITO electrode, eight 5 μm square recesses were formed in the contact hole. Otherwise, a color filter was produced in the same manner as in Example 1 without the reverse taper. The filter thus produced had no defects and excellent uniformity.
[0023]
Example 6
In Example 5, the concave portion was formed with a black photoresist layer provided on the lower surface of the electrode. In this case, a more uniform filter than in Example 5 could be formed. A black photoresist is also provided between the filters and serves as a black mask.
[0024]
Examples 7-12
When a glass substrate was used as the substrate in Examples 1 to 5, a highly uniform filter could be formed in the same manner.
[0025]
Example 13
In Examples 1 to 6, when a urethane-based flexible conductive resin was used as the conductive resin, no connection failure occurred and the uniformity was further improved.
[0026]
Examples 14-19
An overcoat was applied to the color filters prepared in Examples 1 to 6, and then a soluble polyimide alignment film (AL3046: manufactured by Japan Synthetic Rubber) was formed to a thickness of 600 mm. The alignment film of the adjacent color filter is rubbed, and the opposite substrate, which has been subjected to the alignment process in the same manner, is bonded through a silica spacer having a particle size of 6.8 μm so that the rubbing direction forms an angle of 240 °, and Δn An STN type cell was manufactured by injecting a liquid crystal of positive dielectric anisotropy having a dielectric constant of 0.128 and an optically active mixed liquid crystal. Retardation plates having a retardation of 420 nm were provided on the top and bottom of the cell, and the top and bottom were sandwiched with polarizing plates.
When these devices were operated, uniform and good display was achieved.
[0027]
Comparative Example In Example 1, a filter was produced without providing a reverse taper.
This filter had a defect that a filter was not formed on some of the electrodes, and the uniformity of the part where the filter was formed was also inferior to that of Example 1.
[0028]
【effect】
1. There is no conduction failure in the production process. Therefore, it is possible to provide a color filter substrate having a high uniformity, with a high yield rate and no unevenness in film thickness or density due to incomplete electrical connection.
2. In addition to the above effects, it is possible to greatly reduce or eliminate the conduction failure caused by substrate deformation when using conventional resin substrates, especially resin films. Thus, it is possible to provide a color filter substrate having high uniformity without unevenness in film thickness and density due to imperfect electrical connection.
3. In addition to the above effects, the yield rate can be further increased, and there can be provided a color filter having high uniformity without unevenness in film thickness and density due to imperfect electrical connection.
4). A liquid crystal display device with excellent uniformity was obtained because of less uneven density.
5. A color filter substrate having the effects 1 to 3 can be manufactured.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a color filter substrate.
FIG. 2 is a cross-sectional view of a conventional contact hole portion.
FIG. 3 is a cross-sectional view of a contact hole portion having a reverse tapered structure on a wall surface.
FIG. 4A is a cross-sectional view of a contact hole portion having a structure in which a protrusion is provided in the contact hole.
(B) The top view of the contact hole part made into the structure which provided the projection part in the contact hole.
FIG. 5 is a cross-sectional view of a contact hole in FIG. 4 in which the protrusion and the wall surface of the contact hole have an inversely tapered structure.
FIG. 6A is a cross-sectional view of a contact hole including a plurality of contact holes.
(B) A plan view of a contact hole having a plurality of contact holes.
7A is a cross-sectional view of a contact hole in which a recess is provided in the lower part.
(B) The top view of the contact hole which provided the recessed part in the lower part.
FIG. 8 is a cross-sectional view of a contact hole in which a convex portion is provided under the electrode.
[Explanation of symbols]
1 Insulating substrate 2 Electrode 21 Electrode (supports blue color filter)
22 electrodes (supports green color filter)
23 electrodes (supports red color filter)
3 Insulating film 4 Contact hole 41 Contact hole 42 Contact hole 43 Contact hole 44 Contact hole 5 Conductive material 52 Connection to external power supply circuit 53 Connection to external power supply circuit 7 Protrusion 8 Recess 9 Protrusion A Boundary between the immersed and non-immersed parts

Claims (15)

A colored component is deposited on a selected electrode of the patterned electrode on the substrate, an electrode extraction portion on the colored electrode is covered with an insulating film, and a contact hole is formed in a part of the insulating film ; and In a color filter substrate configured by connecting an electrode and an external power source through a conductive material through the contact hole, a plurality of contact holes are provided to form the conductive material, the insulating film, and the electrode in the contact hole. A color filter substrate characterized in that the contact area is increased . A colored component is deposited on a selected electrode of the patterned electrode on the substrate, an electrode extraction portion on the colored electrode is covered with an insulating film, and a contact hole is formed in a part of the insulating film; and In a color filter substrate configured by connecting an electrode and an external power source through a conductive material through the contact hole, by providing a protrusion in the contact hole, the conductive material in the contact hole, the insulating film, and the electrode A color filter substrate characterized in that the contact area to be formed is increased. 3. The color filter substrate according to claim 2, wherein the projection is formed of an insulating material. 4. The color filter substrate according to claim 2, wherein the protrusion is formed by a convex structure provided on the lower surface of the electrode. The color filter substrate according to any one of claims 2 to 4, wherein the protrusion is formed of an inverted taper-shaped protrusion. 6. A structure in which a contact area formed by a conductive material, an insulating film and an electrode in the contact hole is increased by making the wall surface of the contact hole into an inverted taper shape. The color filter substrate according to any one of the above . The color filter substrate according to claim 1, wherein the insulating film and / or the protrusion is formed of a black photoresist film. A colored component is deposited on a selected electrode of the patterned electrode on the substrate, an electrode extraction portion on the colored electrode is covered with an insulating film, and a contact hole is formed in a part of the insulating film; and In a color filter substrate configured by connecting an electrode and an external power source through a conductive material through the contact hole, the conductive material in the contact hole, the insulating film, and the electrode are formed by forming a recess in the lower portion of the contact hole. A color filter substrate characterized in that the contact area to be formed is increased. 9. The color filter substrate according to claim 8, wherein the concave portion provided in the lower portion of the contact hole is formed by a concave structure provided in the lower surface of the electrode. 9. The color filter substrate according to claim 8, wherein the concave portion provided in the lower portion of the contact hole is formed by a pattern of an electrode material. 10. The color filter substrate according to claim 8, wherein the concave portion provided in the lower portion of the contact hole is formed of a black photoresist film. The color filter substrate according to claim 1, wherein the substrate is a resin substrate. The color filter substrate according to any one of claims 1 to 12, wherein the conductive material is formed from a mixed composition of conductive resin that can be deformed following the deformation of the conductive particles and the resin substrate. A liquid crystal display device comprising the color filter substrate according to claim 1 . In order to connect an electrode and an external power supply through a conductive material, a specific electrode of the electrode patterned on the substrate is covered with an insulating film, and contacts a part of the insulating film. A hole is formed, and a patterned electrode substrate provided with a structure for increasing the contact area formed by the conductive material in the contact hole, the insulating film, and the electrode is immersed in an electrolyte containing a coloring component and selected. The method for producing a color filter substrate according to claim 1, wherein a colored component is deposited on the electrode by energizing the prepared electrode.

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