JPH07230100A - Liquid crystal display device and its production - Google Patents

Abstract

PURPOSE:To package ICs for liquid crystal driving with mechanically and electrically high reliability in an initial period and over a long period of time on the transparent electrodes on a glass substrate without being affected by the surface roughness on the electrode surface for packaging the IC by forming plural grooves or holes or recessed parts on the electrodes for packaging the ICs. CONSTITUTION:The surfaces of first and second glass substrates 11a, 11b are respectively provided with the electrodes 12b, etc., for display pixels consisting of indium tin oxide(ITO) and further, the surface of the second glass substrate 11b is provided with the electrodes 13 for packaging the ICs consisting of the same ITO. Electrode pads formed with the grooves 13 of the prescribed pitch and the prescribed width are arranged on the electrodes 13 for packaging the ICs in correspondence to the positions of the projecting electrodes formed on the ICs for liquid crystal driving. The contact area of the electrodes 13 for driving the ICs and a conductive adhesive material is increased by these grooves 13a and, therefore, the strength of adhesion of the ICs for liquid crystal driving and the second glass substrate 11b is improved. The stable adhesion of the surfaces of the electrodes 13 for packaging the ICs and the conductive adhesive material is possible.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a constitution of a liquid crystal display device which carries out active drive or passive drive for displaying characters, symbols and other images, and particularly to liquid crystal drive for electrodes on a glass substrate of a liquid crystal display cell. Of a liquid crystal display device using chip-on-glass mounting, in which a chip of a semiconductor integrated circuit device (hereinafter referred to as IC) for use is directly mounted on a glass substrate using a conductive adhesive material, and this structure is formed. And a manufacturing method therefor.

[0002]

2. Description of the Related Art Generally, in a liquid crystal display device, a liquid crystal display cell and a liquid crystal drive circuit board are made separately, and their connection terminals are electrically connected by heat sealing or a flexible board.

However, recently, due to the demand for a small size and high density liquid crystal display device, a chip on glass (IC) for directly mounting a liquid crystal driving IC on a transparent electrode on a glass substrate of a liquid crystal display cell using a conductive adhesive material ( A COG) mounting method has been proposed and put to practical use.

A general liquid crystal display device to which the COG mounting method is applied will be described below with reference to the drawings. FIG. 3 is a sectional view showing a liquid crystal display device to which a conventional COG mounting method is applied.

On the first glass substrate 31a and the second glass substrate 31b, display pixel electrodes 32a, 32a,
32b, and the IC mounting electrode 33 is further formed on the second glass substrate 31ab.

Liquid crystal alignment layers 34a and 34b are formed on the display pixel electrodes 32a and 32b, respectively, and a liquid crystal layer 35 and a sealing material 36 are provided in a gap between the first glass substrate 31a and the second glass substrate 31b. Enclose by.

Then, the liquid crystal driving IC 38 is connected to the IC mounting electrode 33 through the conductive adhesive material 37 by the protruding electrode 39 formed on the liquid crystal driving IC 38 to form a liquid crystal display device.

FIG. 4 is a plan view showing the IC mounting electrode 33 before mounting the liquid crystal driving IC 38 on the second glass substrate 31b. The IC mounting electrodes 33 are formed by arraying electrode pads corresponding to the positions of the protruding electrodes 39 formed on the liquid crystal driving IC 38.

Next, the manufacturing method of the liquid crystal display device having the above structure will be described by alternately using FIGS.

First, the first glass substrate 31a and the second glass substrate 31b having a transparent electrode film formed on the entire surface are exposed, developed, and etched using a photomask having a predetermined electrode pattern, and then subjected to a predetermined process. The electrode pattern, that is, the display pixel electrodes 32a and 32b and the IC mounting electrode 33 are formed.

Then, polyimide is formed by a printing method on the display electrodes 32a and 32b on the first glass substrate 31a and the second glass substrate 31b, and is further baked, and the surface is rubbed in a certain direction with a cotton cloth. By performing a rubbing process, the liquid crystal alignment layers 34a and 34b are formed.

After that, the first glass substrate 31a and the second glass substrate 31b are bonded to each other by a seal material 36 so that a predetermined space is kept constant, and a liquid crystal material is injected into the space by a vacuum injection method to form a liquid crystal. The layer 35 is formed to obtain a liquid crystal display cell.

Then, the IC mounting electrode 33 formed on the second glass substrate 31a and the protruding electrode 39 of the liquid crystal driving IC 38 are aligned with each other and mounted by using the conductive adhesive material 37, and the liquid crystal display device is completed. obtain.

[0014]

However, in the liquid crystal display device having the above-described structure and manufacturing method, the surface roughness of the IC mounting electrode 33 connecting the liquid crystal driving IC 38 connected via the conductive adhesive material 37. However, there is a problem in that the mounting state becomes unstable in the initial or long-term reliability, because the mechanical and electrical connections are affected by the degree of.

That is, when the liquid crystal display device having the above structure uses the IC mounting electrode 33 having a small surface roughness and a smooth surface, the conductive adhesive materials 37 and I are used.
Adhesion with the C mounting electrode 33 becomes poor. Therefore, instability of connection occurs, and interference fringes or peeling occurs between the conductive adhesive material 37 and the surface of the IC mounting electrode 33 due to heat or mechanical stress, resulting in poor electrical continuity. The problem arises.

On the contrary, when the IC mounting electrode 33 having a large surface roughness is used, the surface area of the IC mounting electrode 33 becomes large at the mounting portion due to the large surface roughness, and the adhesion is improved. Although the connection is good because of the improvement, the surface of the display pixel electrode 32b in the display screen also has a large surface roughness. Therefore, the liquid crystal alignment layer 34b is not uniformly formed, which causes a problem that alignment failure occurs.

The object of the present invention is to solve the above-mentioned problems by providing C
In a liquid crystal display device by the OG mounting method, a conductive adhesive material is used for a transparent electrode formed on a glass substrate of the liquid crystal display device without being affected by the surface roughness of the IC mounting electrode surface, and the mechanical and mechanical properties are improved. An object of the present invention is to provide a liquid crystal display device which mounts a liquid crystal driving IC that is electrically excellent in initial reliability and long-term reliability, and a manufacturing method thereof.

[0018]

In order to achieve the above object, the constitution of the liquid crystal display device of the present invention and the manufacturing method thereof adopt the following means.

In the liquid crystal display device of the present invention, a liquid crystal layer is sealed between a plurality of glass substrates provided with electrodes for display pixels by using a sealing material, and a conductive adhesive is applied on the IC mounting electrodes provided on the glass substrate. A liquid crystal driving IC fixed through a material, wherein the IC mounting electrode has a plurality of grooves or a plurality of holes,
Alternatively, it is characterized by having a plurality of recesses.

According to the method of manufacturing a liquid crystal display device of the present invention, a transparent electrode is formed on the entire surface of a glass substrate, and an IC mounting electrode having a plurality of grooves, holes or recesses and a display pixel electrode are simultaneously formed by photoetching. Then, the liquid crystal alignment layer is formed on the display pixel electrode, the liquid crystal alignment layer is rubbed, the glass substrates are laminated with a sealing material, the liquid crystal material is injected to form the liquid crystal layer, and the liquid crystal layer is formed on the IC mounting electrode. In addition, the liquid crystal driving IC is fixed by using a conductive adhesive material.

According to the method of manufacturing a liquid crystal display device of the present invention, a transparent electrode is formed on the entire surface of a glass substrate, and the IC mounting electrode uses a photomask in which a pattern of grooves, holes or recesses exceeding the resolution limit is formed. An IC mounting electrode and a display pixel electrode are formed at the same time, a liquid crystal alignment layer is further formed on the display pixel electrode, the liquid crystal alignment layer is rubbed, and a glass substrate is attached by a sealing material to form a liquid crystal material. A liquid crystal layer is formed by injecting the liquid crystal layer, and the liquid crystal driving IC is fixed on the IC mounting electrode using a conductive adhesive material.

[0022]

By forming a plurality of grooves, holes, or recesses on the IC mounting electrode according to the present invention, only the surface of the IC mounting electrode is made rough without affecting the liquid crystal alignment layer, and the surface area is increased. It has been done.

Therefore, when the liquid crystal driving IC is directly mounted on the IC mounting electrode on the glass substrate using the conductive adhesive material, regardless of the surface roughness of the film itself of the IC mounting electrode to be formed. It is possible to increase the contact area between the conductive adhesive material and the IC mounting electrode.

As a result, it becomes possible to improve the adhesiveness between the conductive adhesive material and the IC mounting electrode, so that a very stable connection can be realized and a liquid crystal display device having excellent reliability can be obtained. Obtainable.

Further, when forming the display pixel electrode pattern, a plurality of grooves, holes, or recesses are formed only in the IC mounting electrode at the same time as the display pixel electrode.
Therefore, the mounting stability can be improved without adding an additional processing step such as roughening only the surface of the IC mounting electrode after forming the electrode pattern.

[0026]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view showing a liquid crystal display device according to an embodiment of the present invention, and FIG. 2 is a plan view showing the liquid crystal display device before mounting a liquid crystal driving IC. Hereinafter, description will be given with reference to FIG. 1 and FIG. 2 alternately. First, the structure of the liquid crystal display device of the present invention will be described.

As shown in FIG. 1, the first glass substrate 11
The display pixel electrode 12 made of indium tin oxide (ITO) is formed on each of the a and the second glass substrate 11b.
a and 12b are provided, and the IC mounting electrode 13 made of the same ITO is provided on the second glass substrate 11b.

Liquid crystal alignment layers 14a and 14b made of polyimide are provided on the display pixel electrodes 12a and 12b, respectively.

Further, the first glass substrate 11a and the second glass substrate 11b are overlapped with each other by a sealing material 16 made of an epoxy adhesive so as to keep a uniform gap, and the liquid crystal layer 15 is sealed in the gap.

Further, COG mounting is applied in which the liquid crystal driving IC 18 provided on the IC mounting electrode 13 and the protruding electrode 19 are directly mounted via the conductive adhesive material 17.

The IC mounting electrode 13 is used for the liquid crystal driving IC 1.
Corresponding to the position of the protruding electrode 19 formed in FIG.
The electrode pads formed with are arranged. In FIG. 1, the groove 1
Although the ITO film on the portion 3a is removed, the ITO film may be left on the bottom surface of the groove 13a.

With respect to the liquid crystal display device configured as described above, a manufacturing method for forming the structure will be described below with reference to FIGS. 1 and 2.

On a glass substrate having a very smooth surface roughness (15 nm or less) which is very good for liquid crystal alignment,
ITO (indium tin oxide) is formed as a transparent electrode film by a sputtering method.

After that, a photoresist OMR manufactured by Tokyo Ohka Kogyo Co., Ltd. is formed on the ITO-formed glass substrate by spin coating.

After prebaking, the display pixel electrodes 12a, 1
Exposure and development processes are performed using a photomask having a pattern of 2b and a pattern of IC mounting electrodes 13 corresponding to a groove 13a having a width of 3 μm and a pitch of 10 μm. After that, post bake processing is performed.

Then, using the patterned photoresist as an etching mask, the ITO is etched, and the photoresist is stripped off to form display pixel electrodes 12a and 12b having a predetermined shape, and an IC mounting electrode 13. First glass substrate 11a on which the respective
And the second glass substrate 11b are obtained.

After that, polyimide is formed on the display pixel electrodes 12a and 12b by offset printing, and the temperature is set to 2
A firing process is performed at 00 ° C.

Then, a rubbing treatment is carried out by rubbing in a certain direction with a cotton cloth to form the liquid crystal alignment layers 13a and 13b.
First glass substrate 11a and second glass substrate 1 respectively
1b.

Next, the first glass substrate 11a and the second glass substrate 11b are bonded to each other with the seal material 16 so as to keep the space of 6 μm, and the liquid crystal material is injected into the space by the vacuum injection method to form the liquid crystal layer 15. To form a liquid crystal display cell.

Then, the IC mounting electrode 13 formed on the second glass substrate 11b and the protruding electrode 19 are aligned with each other, and the liquid crystal driving IC 18 is mounted using the conductive adhesive material 17 to complete the liquid crystal display device. obtain.

In the liquid crystal display device according to the present invention, the groove 13a formed in the IC mounting electrode 13, which is the mounting region,
The contact area between the IC mounting electrode 13 and the conductive adhesive material 17 increases. Therefore, the bonding strength between the liquid crystal driving IC 18 and the second glass substrate 11b is improved.

Therefore, the surface of the IC mounting electrode 13 and the conductive adhesive material 17 can be stably bonded.

The results of the reliability test of the liquid crystal display device of the present invention will be described below. Temperature 65 ℃ Humidity 90%
Even after being left to stand for 10 days in the RH environment, no interference fringes showing a peeling phenomenon are generated at the interface between the IC mounting electrode 13 and the conductive adhesive material 17, and good connection is obtained. It could be confirmed.

In the embodiment of the present invention, the IC mounting electrode 13 is used.
Formed a groove 13a having a pitch of 10 μm and a width of 3 μm. Instead of the groove 13a, grid-like grooves 53a as shown in FIGS. 5, 6 and 7 and a plurality of holes 6 were formed.
The same effect as described above can be obtained by forming 3a or a plurality of recesses 73a.

Here, the grooves 13a, the grid-like grooves 53a, and the holes 6 are formed.
The cross-sectional shapes of 3a and the recess 73a are rectangular or trapezoidal. Further, the planar shapes of the hole 63a and the recess 73a are circular or polygonal.

In the embodiment of the present invention, the display pixel electrode 12 having a predetermined shape is formed by photolithography and etching.
Although a and 12b and the IC mounting electrode 33 are formed, the IC mounting electrode 1 is formed by forming an electrode pattern by a printing method.
It is also possible to form a plurality of grooves 13a, a grid-shaped groove 53a, a plurality of holes 63a, or a plurality of recesses 73a only in the number 3.

As another manufacturing method, when the electrode pattern is formed by the photolithography method as in the embodiment described with reference to FIGS. 1 and 2, the design rule exceeding the resolution limit in the region of the IC mounting electrode 13 is used. Grooves 13a, 53a by size
Alternatively, a pattern can be formed by using a photomask provided with a pattern of the holes 63a or the recesses 73a.

When an exposure process and a development process are performed using a photomask having such a pattern, a plurality of grooves 13a and 53a having a perfect shape, or a plurality of holes 63a, are formed in the IC mounting electrode 13. Although the recess 73a is not formed, a thin area of the photoresist having a groove shape or a hole shape is formed on the surface of the IC mounting electrode 13. Then, an etching process is performed using this photoresist, and the effect of improving the adhesion between the surface of the IC mounting electrode 13 and the conductive adhesive material 17 can be obtained.

For example, a pitch dimension of 5 μm and 1.5
When an IC mounting electrode is formed by a photomask having a plurality of groove patterns each having a width of μm, the groove pattern has a design rule exceeding the resolution limit. The photoresist is thinly formed.

Then, after etching the photoresist having such a film thickness distribution using the etching mask, a pattern can be formed on the IC mounting electrode 13 at a position corresponding to the groove or hole.

In the embodiment described above, the liquid crystal layer 15
Although the liquid crystal driving IC 18 is mounted after the formation, the liquid crystal driving IC 18 may be mounted before the liquid crystal layer 15 is formed. Further, the display pixel electrodes 12a and 12b and I
The C mounting electrode 13 has been described as an example in which a transparent conductive film made of ITO is applied, but these may be metal thin films.

[0052]

As described above, according to the structure of the liquid crystal display device of the present invention and the manufacturing method thereof, a plurality of grooves, a plurality of holes, or a plurality of holes are formed in the IC mounting electrode for mounting the liquid crystal driving IC. A plurality of recesses are formed.

As a result, when a liquid crystal driving IC is mounted on the IC mounting electrode using a conductive adhesive material, the I of the mounting portion is not impaired without damaging the alignment film characteristics of the liquid crystal.
The adhesion between the C mounting electrode and the conductive adhesive material can be improved, and a strong connection can be achieved.

As a result, it is possible to realize a liquid crystal display device to which the COG mounting method is applied, which is stable and reliable against thermal stress and mechanical stress.

Further, since a plurality of grooves, a plurality of holes, or a plurality of recesses are formed only in the IC chamber mounting electrode portion for mounting the liquid crystal driving IC at the same time as the pixel display electrode pattern forming step, only the mounting portion is formed. It is not necessary to roughen the surface in a separate step.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a configuration of a liquid crystal display device and a manufacturing method thereof in an embodiment of the present invention.

FIG. 2 is a plan view showing a configuration of a liquid crystal display device and a manufacturing method thereof according to an embodiment of the present invention.

FIG. 3 is a cross-sectional view showing a conventional liquid crystal display device.

FIG. 4 is a plan view showing a conventional liquid crystal display device.

FIG. 5 is a diagram of I in a liquid crystal display device according to an embodiment of the present invention.
It is a top view which shows the C mounting electrode area.

FIG. 6 is a view of I in the liquid crystal display device according to the embodiment of the present invention.
It is a top view which shows the C mounting electrode area.

FIG. 7 is a diagram of I in the liquid crystal display device according to the embodiment of the present invention.
It is a top view which shows the C mounting electrode area.

[Explanation of symbols]

 11a First Glass Substrate 11b Second Glass Substrate 12a Display Pixel Electrode 13 IC Mounting Electrode 13a Groove 14a Liquid Crystal Alignment Layer 15 Liquid Crystal Layer 16 Sealing Material 17 Conductive Adhesive Material 18 Liquid Crystal Driving IC

Claims (14)

[Claims] 1. A liquid crystal drive in which a liquid crystal layer is sealed between a plurality of glass substrates provided with display pixel electrodes by using a sealing material, and a liquid crystal drive is fixed on an IC mounting electrode provided on the glass substrate via a conductive adhesive material. And an IC mounting electrode, wherein the IC mounting electrode has a plurality of grooves. 2. A liquid crystal drive in which a liquid crystal layer is sealed between a plurality of glass substrates provided with display pixel electrodes by using a sealing material, and a liquid crystal drive is fixed on an IC mounting electrode provided on the glass substrate via a conductive adhesive material. Liquid crystal display device, wherein the IC mounting electrode has a plurality of parallel grooves. 3. A liquid crystal drive in which a liquid crystal layer is sealed between a plurality of glass substrates provided with electrodes for display pixels by using a sealing material, and a liquid crystal drive which is fixed on an IC mounting electrode provided on the glass substrate via a conductive adhesive material. Liquid crystal display device, wherein the IC mounting electrode has a plurality of grid-shaped grooves. 4. The liquid crystal display device according to claim 1, 2 or 3, wherein the cross section of the groove provided in the IC mounting electrode is rectangular or trapezoidal. 5. A liquid crystal drive in which a liquid crystal layer is sealed between a plurality of glass substrates provided with display pixel electrodes by using a sealing material, and a liquid crystal drive is fixed on an IC mounting electrode provided on the glass substrate via a conductive adhesive material. Liquid crystal display device, characterized in that the IC mounting electrode has a plurality of holes. 6. The liquid crystal display device according to claim 5, wherein the hole formed in the IC mounting electrode is rectangular or trapezoidal in cross section. 7. The liquid crystal display device according to claim 5, wherein the planar shape of the hole provided in the IC mounting electrode is circular or polygonal. 8. A liquid crystal drive, wherein a liquid crystal layer is sealed between a plurality of glass substrates provided with display pixel electrodes by using a sealing material, and liquid crystal driving is fixed onto an IC mounting electrode provided on the glass substrate via a conductive adhesive material. Liquid crystal display device, characterized in that the IC mounting electrode has a plurality of recesses. 9. The liquid crystal display device according to claim 8, wherein the recessed portion of the IC mounting electrode has a rectangular cross section or a trapezoidal cross section. 10. The liquid crystal display device according to claim 8, wherein the planar shape of the concave portion provided in the IC mounting electrode is a circular shape or a polygonal shape. 11. A transparent electrode is formed on the entire surface of a glass substrate, and an IC mounting electrode having a plurality of grooves, holes or recesses and a display pixel electrode are simultaneously formed by photoetching, and a liquid crystal alignment layer is provided for the display pixel. Formed on the electrode,
The liquid crystal alignment layer is rubbed, the glass substrates are laminated with a sealing material, the liquid crystal material is injected to form the liquid crystal layer, and the liquid crystal driving IC is fixed on the IC mounting electrode using a conductive adhesive material. A method for manufacturing a liquid crystal display device, comprising: 12. A transparent electrode is formed on the entire surface of a glass substrate, and an IC mounting electrode having a plurality of grooves, holes or recesses and a display pixel electrode are simultaneously formed by photoetching, and a liquid crystal alignment layer is provided for a display pixel. Formed on the electrode,
The liquid crystal alignment layer is rubbed, the glass substrates are laminated with a sealing material, the liquid crystal driving IC is fixed on the IC mounting electrode using a conductive adhesive material, and the liquid crystal material is injected to form the liquid crystal layer. A method for manufacturing a liquid crystal display device, comprising: 13. An IC mounting electrode and a display pixel electrode are formed by using a photomask having a transparent electrode formed on the entire surface of a glass substrate, and the IC mounting electrode having a pattern of grooves or holes exceeding the resolution limit. Formed at the same time, a liquid crystal alignment layer is formed on the display pixel electrode, the liquid crystal alignment layer is rubbed, and a glass substrate is attached by a sealing material,
A method for manufacturing a liquid crystal display device, comprising injecting a liquid crystal material to form a liquid crystal layer, and fixing the liquid crystal driving IC on the IC mounting electrode with a conductive adhesive material. 14. A transparent electrode is formed on the entire surface of a glass substrate, and the IC mounting electrode and the display pixel electrode are formed by using a photomask having a pattern of grooves or holes exceeding the resolution limit. Formed at the same time, a liquid crystal alignment layer is formed on the display pixel electrode, the liquid crystal alignment layer is rubbed, and a glass substrate is attached by a sealing material,
A method of manufacturing a liquid crystal display device, comprising: fixing a liquid crystal driving IC on an IC mounting electrode using a conductive adhesive material and injecting the liquid crystal material to form a liquid crystal layer.