JPH05224226A - Structure of transparent conductive thin film formed on film substrate and formation therefof - Google Patents

Abstract

PURPOSE:To provide the structure of the transparent conductive thin films which eliminate the cracks generated at the time of connection in the state of lowering the specific resistance of the transparent conductive thin films and eliminates the problem that electrode patterns are visible. CONSTITUTION:A liquid crystal display cell is formed by forming the respectively striped transparent conductive thin films 2 on the inner side of a pair of film substrates 1A, 1B, sticking these film substrates 1A, 1B to each other, injecting a liquid crystal 4 therebetween and connecting the juncture S of the transparent conductive thin films 2 existing on the outer side of the film substrate 1A to the connecting terminal of a driving circuit board. The film thickness 2a of the transparent conductive thin films connected to the connecting terminal of the driving circuit board and the film thickness 26 of the parts where a sealant 3 exist are formed smaller than the film thickness in the part of the other striped transparent conductive thin film 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of a transparent conductive thin film connecting portion of a film substrate of a liquid crystal display element connected to a connecting terminal of a driving circuit substrate and its vicinity, and a method of forming the same.

[0002]

2. Description of the Related Art When a transparent conductive thin film formed on a film substrate used for a liquid crystal display device or the like is connected to a connecting terminal of a driving circuit substrate by a thermocompression bonding method or the like, a crack is formed on the transparent conductive thin film on the film substrate side. It causes the problem of entering and breaking. In particular, when driving a large-capacity dot matrix electrode with a high duty such as having a pixel number of 640 × 400 dot matrix class in an LCD panel having a diagonal size of 9 to 10 inches, the ratio of the transparent conductive thin film is It is necessary to increase the film thickness in order to reduce the resistance. In this case, the film thickness is required to be 1000Å to 3000Å, and the above-mentioned problem that the connecting portion of the transparent conductive thin film is disconnected due to the connection is remarkable. ..

Further, in the film thickness of the conventional transparent conductive thin film, the light transmittance is reduced by this transparent conductive thin film, and the difference in the transmittance becomes large depending on the presence or absence of the pattern of the transparent conductive thin film. The so-called visibility of the electrode pattern when not lit is a problem.

[0004]

DISCLOSURE OF THE INVENTION The present invention solves the conventional problems that occur in a transparent conductive thin film formed on a film substrate and, at the time of connection, when the specific resistance of the transparent conductive thin film is low. It is an object of the present invention to provide a structure of a transparent conductive thin film that eliminates cracks that have occurred and does not cause a problem of the appearance of an electrode pattern.

[0005]

In order to achieve the above object, the present invention provides a transparent conductive thin film formed in a stripe shape on the side of a film substrate, which is connected to a connection terminal of a drive circuit substrate. The thickness of the transparent conductive thin film is characterized in that, among the transparent conductive thin films formed in a stripe shape, the connection portion with the connection terminal is formed thin.

According to the present invention, stripe-shaped transparent conductive thin films are formed inside a pair of film substrates, and the pair of film substrates are bonded to each other to inject a liquid crystal. In a liquid crystal display cell that connects the connection part of the thin film to the connection terminal of the drive circuit board, the film thickness of the transparent conductive thin film is the thickness of the part connected to the connection terminal of the drive circuit board, and the other stripe-shaped transparent conductive film. It is characterized in that it is formed thinner than the thin film portion.

Further, according to the present invention, the thickness of the transparent conductive thin film is not limited to the portion connected to the connection terminal of the drive circuit board, the portion contacting with the sealing agent, and the portion between the sealing agent and the effective display portion. Each is characterized by being thinned, and the thinned film thickness is characterized by being 300 Å or more and 1000 Å or less.

Further, according to the present invention, a stripe-shaped transparent conductive thin film is formed inside each of a pair of film substrates, and the pair of film substrates are bonded to each other to inject a liquid crystal. In a liquid crystal display cell in which the connection part of the conductive thin film is connected to the connection terminal of the drive circuit board and the dot matrix display part and other display part are provided as the transparent conductive thin film, the film thickness of the transparent conductive thin film is dot matrix display. It is characterized in that the thickness of the portion is set to a normal thickness, and the thickness of the portion to be connected and the portion other than the dot matrix display portion is thin.

Further, according to the present invention, a transparent conductive thin film having a stripe shape is formed inside each of a pair of film substrates, and the pair of film substrates are bonded together to inject a liquid crystal. In a liquid crystal display cell in which the connection part of the conductive thin film is connected to the connection terminal of the drive circuit board, the liquid crystal display cell after the pair of film substrates are bonded together is placed in an etching atmosphere, and the transparent conductive film is exposed to the outside. It is characterized in that the connecting portion of the conductive thin film is formed thin.

[0010]

With the structure of the present invention, the specific resistance of the transparent conductive thin film is lowered by forming the thin film thickness of the transparent conductive thin film portion on the film substrate connected to the connection terminal of the drive circuit substrate. In, in the connection by thermocompression bonding, it was possible to secure the reliability of the connection without generating a crack in the transparent conductive thin film.

[0011]

EXAMPLES Examples of the present invention will be described below. In order to explain the basic structure of the present invention, the film thickness (A) of a transparent conductive thin film formed in stripes on a film substrate, and the film substrate having the film thickness (A) and the drive circuit substrate Table 1 shows the ratio of the number of transparent conductive thin film patterns in which cracks have occurred to the total number of transparent conductive thin film patterns when the connection terminals are thermocompression bonded.

[Table 1]

The results shown in Table 1 are obtained by performing thermocompression bonding with higher heat and pressure than normal thermocompression bonding conditions to improve the defect detection capability, and to optimize the thermocompression bonding conditions. Although it is possible to expand the range of film thickness where cracks occur, in order to ensure reliability of products such as liquid crystal display devices over a long period of time, from the results of the above experiment,
It was revealed that setting the thickness of the transparent conductive thin film to 1000 Å or less gives good results. (1 What is the film thickness of a normal transparent conductive thin film, and when the non-resistance of the transparent conductive thin film is reduced?)

Next, a first embodiment of the present invention will be described. On the film substrate 1, indium tin oxide (IT
The transparent conductive thin film 2 made of O) is formed as a stripe pattern, and its plan view is shown in FIG. 1 and its cross-sectional view is shown in FIG. The transparent conductive thin film 2 of the film substrate 1 has a connection portion S connected to a connection terminal of a drive circuit board (not shown), and the film thickness A of the transparent conductive thin film 2a of the connection portion S is transparent. It is configured to be thinner than the film thickness of the conductive thin film 2. In this Example 1, the transparent conductive thin film 2 having a film thickness of about 2000 Å is formed on the film substrate 1, and the transparent conductive thin film 2a of the connection portion S has a thickness of 80.
The film thickness was 0Å.

The thickness of the transparent conductive thin film 2a of the connecting portion S is set to 1
It has been confirmed that the transparent conductive thin film 2a is not cracked in the connection by thermocompression bonding to the drive circuit board by setting it to 000Å or less. Further, when the film thickness of the transparent conductive thin film 2a of the connecting portion S is set to 300 Å or less,
Although the specific resistance of the transparent conductive thin film 2a of the connection portion S is increased, it is desirable that the connection resistance is not significantly increased by setting the film thickness to 500 Å or more, and there is no problem as a product. It was revealed. The film thickness of the transparent conductive thin film 2a of the connection portion S is 300 Å or more,
If it is 1000Å or less, the conventional defects can be solved,
800 Å was adopted as the optimum film thickness.

The transparent conductive thin film 2a of such a connecting portion S is formed.
In order to obtain the film thickness of, the transparent conductive thin film is vapor-deposited through a mask on the opposing surface of the film substrate respectively, or the conductive thin film is deposited on the entire surface, and resist coating, development, etching and cleaning are performed. After an electrode pattern is formed through the steps, an alignment layer is formed, a rubbing treatment is performed, and a film substrate is bonded via a sealant, the present invention provides (CF ₄ +
Dry etching atmosphere such as O ₂ or (hydrochloric acid +
By placing the laminated liquid crystal display cell in a wet etching atmosphere such as ferric chloride + water),
The film thickness of the transparent conductive thin film 2a of the connecting portion 3 with the drive circuit board which is exposed to the outside can be formed thin.

Next, a second embodiment of the present invention will be described. In Example 2, in the transparent conductive thin film 2 formed on the film substrate 1, in addition to the transparent conductive thin film 2a portion of the connecting portion S in Example 1, the transparent conductive thin film 2b portion where the sealant 3 is located is It is configured to be thinner than the film thickness of the transparent conductive thin film 2 in contact with the liquid crystal 4. Since the two film substrates 1A and 1B are attached to each other, an epoxy-based sealing agent 3 is applied to the peripheral portion of either one of the film substrates 1A and 1B. In this case, the adhesive force can be increased by roughening the surfaces of the film substrates 1A and 1B with which the sealant 3 is in contact.

As shown in FIGS. 3 and 4, in this embodiment, the sealing agent 3 of the transparent conductive thin film 2 formed on the film substrate is brought into contact with the film in the same manner as in the first embodiment. Transparent conductive thin film 2 from part to connection part S
The portions a and 2b are thinly formed by etching to roughen the surface of the portion where the sealant 3 is located and the portion of the connection portion S, thereby increasing the adhesive strength with the sealant 3.
In this case, the transparent conductive thin film 2 located at the connecting portion S
Since a is also formed thin, the connection with the connection terminal of the drive circuit board can be improved.

A third embodiment of the present invention is shown in FIGS. In this embodiment, the transparent conductive thin film 2 formed on the film substrate 1 is formed thin except for the effective display portion H of the liquid crystal display cell. In a liquid crystal display cell, two film substrates 1 are generally provided with a sealant 3.
Although A and 1B are pasted together, the sealant 3 cannot be crushed to a desired thickness, and the space in the vicinity of the sealant 3 tends to be thicker than in the central portion of the liquid crystal display cell. In such a liquid crystal display cell, color unevenness occurs near the seal.

In the embodiment of the present invention, in order to prevent the occurrence of the color unevenness in the liquid crystal display cell, the film thickness of the transparent conductive thin film 2 located outside the effective display portion H of the liquid crystal display cell, that is, , A portion 2a of the connecting portion, a portion 2b where the sealant 3 is located, and an inner portion 2c where the sealant 3 is located
The film thickness of the transparent conductive thin film in the above was set to a thin thickness of about 800Å. Therefore, it was found that the thickness of the liquid crystal 4 housed inside the sealant 3 can be made uniform up to the vicinity of the sealant 3.

By thinning the transparent conductive thin film 2c in the vicinity of the sealant 3, the film substrate becomes less stiff and the sealant 3 is easily crushed. Further, in the third embodiment, the liquid crystal display device in which the sealing strength shown in the first and second embodiments is increased and the connection with the drive circuit board is good can be realized.

7 and 8 show Embodiment 4 of the present invention. In this embodiment, the liquid crystal display device is provided with a dot matrix display portion M and a fixed character display portion K, and the pattern of the fixed character display portion and the wiring electrodes associated therewith can be clearly seen when not illuminated. There is a problem that the electrodes are visible. This problem,
In particular, it is remarkable when a low resistance transparent conductive thin film is used, and because the transparent conductive thin film is thick, the difference in light transmittance between the part with the transparent conductive thin film and the part without the transparent conductive thin film is large. This is because it becomes larger.

In Embodiment 4 of the present invention, as shown in FIGS. 7 and 8, the transparent conductive thin film other than the dot matrix display portion M in the effective display portion is thinned to about 800 Å. Therefore, in this example, it was possible to prevent the electrodes from being seen, and at the same time, it was possible to realize the liquid crystal display device having the excellent action and effect shown in Examples 1 to 3.

[0023]

The structure of the present invention has the effect of eliminating cracks generated in the transparent conductive thin film when the film substrate and the driving circuit substrate are thermocompression-bonded to each other. By reducing the thickness to the above range, the adhesive strength of the sealant can be increased, the color unevenness occurring in the liquid crystal display cell can be eliminated, and the phenomenon of electrode appearance can be prevented.

[Brief description of drawings]

FIG. 1 is a plan view showing a structure of a transparent conductive thin film on a film substrate according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional view of the transparent conductive thin film portion of FIG.

FIG. 3 is a plan view showing an arrangement of transparent conductive thin films in a liquid crystal display cell in which a pair of film substrates according to a second embodiment of the present invention are joined.

FIG. 4 is a cross-sectional view showing the configuration of the transparent conductive thin film in FIG.

FIG. 5 is a plan view showing an arrangement of transparent conductive thin films in a liquid crystal display cell in which a pair of film substrates according to Example 3 of the present invention are joined.

6 is a cross-sectional view showing the structure of the transparent conductive thin film in FIG.

FIG. 7 is a plan view showing an arrangement of transparent conductive thin films in a liquid crystal display device having a dot matrix display section and a fixed character display section according to Example 4 of the present invention.

FIG. 8 is a cross-sectional view showing the configuration of the transparent conductive thin film in FIG.

[Explanation of symbols]

1 Film Substrate 2 Transparent Conductive Thin Film 2a Transparent Conductive Thin Film 2b Connected to Driving Circuit Board 2c Transparent Conductive Thin Film at the Position of Sealant 2c Transparent Conductive Thin Film between Effective Display Area and Sealant 3 Sealant 4 Liquid crystal S Connection with drive circuit board H Effective display area M Dot matrix display area K Fixed character display area

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yuji Narumi 1-3-6 Nakamagome, Ota-ku, Tokyo Within Ricoh Company (72) Inventor Hiroshi Fujimura 1-3-6 Nakamagome, Ota-ku, Tokyo Shares Inside Ricoh Company (72) Inventor Hisao Takahashi 1-3-6 Nakamagome, Ota-ku, Tokyo Stock Company Ricoh (72) Inventor Hiroyuki Sakayori 1-3-6 Nakamagome, Tokyo Stockholder Ricoh Company

Claims (7)

[Claims] 1. A structure of a transparent conductive thin film formed in a stripe shape on the side of a film substrate connected to a connection terminal of a drive circuit board, wherein the thickness of the transparent conductive thin film is the transparent conductive film formed in a stripe shape. A structure of a transparent conductive thin film formed on a film substrate, characterized in that a connecting portion with the connection terminal is thinly formed in the conductive thin film. 2. A stripe-shaped transparent conductive thin film is formed inside each of a pair of film substrates, the pair of film substrates are bonded to each other to inject a liquid crystal, and a transparent conductive thin film located outside the film substrate is formed. In a liquid crystal display cell in which the connection portion is connected to the connection terminal of the drive circuit board, the thickness of the transparent conductive thin film is the thickness of the portion connected to the connection terminal of the drive circuit board to that of another stripe-shaped transparent conductive thin film. A structure of a transparent conductive thin film formed on a film substrate of a liquid crystal display device characterized by being formed thinner than a portion. 3. The film thickness of the transparent conductive thin film is such that the film thickness from the part connected to the connection terminal of the drive circuit board to the part in contact with the sealant is smaller than that of the other striped transparent conductive thin film. The structure of the transparent conductive thin film formed on the film substrate of the liquid crystal display device according to claim 2, wherein the structure is thin. 4. The film thickness of the transparent conductive thin film is such that the film thickness from the portion connected to the connection terminal of the drive circuit board to the outside of the effective display portion of the liquid crystal is more than that of the transparent conductive thin film portion of the effective display portion. The structure of the transparent conductive thin film formed on the film substrate of the liquid crystal display device according to claim 2, wherein the structure is thin. 5. A stripe-shaped transparent conductive thin film is formed inside each of a pair of film substrates, the pair of film substrates are bonded to each other to inject a liquid crystal, and a transparent conductive thin film located outside the film substrate is formed. In a liquid crystal display cell having a dot matrix display section and another display section as a transparent conductive thin film, the connection section is connected to a connection terminal of a drive circuit board,
The film thickness of the transparent conductive thin film is the film thickness of the dot matrix display portion being a normal thickness, and the film thickness of the connection portion and the portion other than the dot matrix display portion is formed thin. Structure of the transparent conductive thin film formed on the substrate. 6. The transparent conductive thin film formed on the film substrate according to claim 1, wherein the thin film thickness of the transparent conductive thin film is 300 Å or more and 1000 Å or less. Construction. 7. A stripe-shaped transparent conductive thin film is formed inside each of a pair of film substrates, the pair of film substrates are bonded to each other, liquid crystal is injected, and a transparent conductive thin film positioned outside the film substrate is formed. In a liquid crystal display cell in which a connection portion is connected to a connection terminal of a drive circuit board, the liquid crystal display cell after the pair of film substrates are bonded together is placed in an etching atmosphere, and a transparent conductive thin film that is exposed to the outside is connected. A method for forming a transparent conductive thin film, characterized in that the film thickness of a portion is formed thin.