JPH1152408A - Tab packaged liquid crystal display element, and method for packaging tab on liquid crystal display element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate the need for using an anisotropic conductive film (or anisotropic conductive paste) by bonding electrodes which are formed on a tab(TAB) surface at given intervals and have irregularities on the surfaces and the transparent electrode of the liquid crystal display element with a setting type adhesive and also connecting them electrically. SOLUTION: The electrode (surface-roughened copper foil) 22 of TAB packaged on the transparent electrode 12 of a liquid crystal panel has irregularities. The adhesive is applied between a transparent electrode extraction part and the electrode of a TAB board 21. A thermosetting adhesive is used as this adhesive. The transparent electrode extraction part 12 to be mounted is coated with the thermosetting adhesive. The extraction part 12 of the transparent electrode and the electrode 22 of TAB are positioned. A projection part of the TAB electrode is pressed against the transparent electrode 12 by being pressed. Thus, the transparent electrode 12 and TAB are packaged without using an anisotropic conductive film or anisotropic paste, and the electrode pitch of the transparent electrode and the electrode pitch of TAB are both made small.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a TAB-mounted liquid crystal display device and a liquid crystal display device and a method for mounting a TAB.

[0002]

2. Description of the Related Art Conventionally, TAB is mounted on a liquid crystal display element via an anisotropic conductive film. That is, an anisotropic conductive film is attached to either the transparent electrode to be connected or the TAB electrode portion. If the tack force of the anisotropic conductive film itself is insufficient, the end of the anisotropic conductive film may be fixed with an adhesive tape. Next, TAB or the transparent electrode side substrate is positioned and heat-sealed. In many cases, the heat sealing is usually performed in two steps of temporary compression bonding and main compression bonding.

At present, the ratio between the width of the electrode to be connected and the particle size of the anisotropic conductive film is about 10: 1. In recent years, there has been a demand for high-density packaging for high-density liquid crystal panels, and therefore, those having a small conductive particle diameter have been developed.
It is around μm. Therefore, as the densification progresses more and more, it becomes difficult to connect with high reliability with the current anisotropic conductive film.

[0004]

SUMMARY OF THE INVENTION The present invention relates to a liquid crystal display device having a TAB mounted thereon without using an anisotropic conductive film (or an anisotropic conductive paste) and a method for applying a TAB to the liquid crystal display device.
B is to provide a mounting method.

[0005]

According to a first aspect of the present invention, in a liquid crystal display device in which a substrate having a pair of transparent electrodes sandwiches liquid crystal molecules and a TAB is mounted, a predetermined interval is provided between the TAB surfaces. The present invention relates to a TAB-mounted liquid crystal display element, characterized in that an electrode formed with a gap and having irregularities on its surface and a transparent electrode of the liquid crystal display element are joined and electrically connected by a curable adhesive.

A second aspect of the present invention is a liquid crystal display device comprising a TAB electrode formed at predetermined intervals on a TAB surface and having irregularities on its surface, and a substrate having a pair of transparent electrodes sandwiching liquid crystal molecules. After pressing and joining to a predetermined position of the transparent electrode to such an extent that the positions of the two electrodes do not shift, a photo-curing or thermosetting adhesive is applied to TAB and photo-cured or thermo-cured. To mount a liquid crystal display element and a TAB.

Hereinafter, the present invention will be specifically described with reference to the drawings. 1. 1 and 2 show one example of a TAB-mounted liquid crystal display device of the present invention. This liquid crystal display element has irregularities on an electrode (copper foil whose surface is roughened) 22 of the TAB 20 mounted on the transparent electrode 12 of the liquid crystal panel 10. The method of forming the irregularities may be a method of shaving the electrode surface or a method of forming a convex portion. As a method of shaving the electrode surface, for example, a method using a paper file is used. When shaving with a paper file or the like, the size of the concave portion is random, but the effect of the present invention is high if the average value of the interval between the concave portions is 10% or less between the TAB electrodes. An adhesive is applied between the transparent electrode lead-out portion and the electrode of the TAB substrate 21. A thermosetting adhesive is used as this adhesive. Also, an adhesive having the lowest possible viscosity is desirable. For example, 3042 manufactured by Three Bond Co. can be used because it has a viscosity of 20 cP and is a thermosetting adhesive. A thermosetting adhesive is applied to the transparent electrode lead-out portion 12 to be mounted. If a dispenser is used when applying, the adhesive is not applied more than necessary. The alignment between the lead portion 12 of the transparent electrode and the electrode 22 of the TAB is performed. Generally, both electrodes are aligned by applying alignment marks to both and aligning them. The bonded part is pressurized and heated by a heat seal crimping machine or the like. Even if the adhesive is applied to the TAB side, the transparent electrode side and the TAB
Even if it attaches to both sides, there is no change in the effect of the present invention. As long as the viscosity of the adhesive is not extremely large, the adhesive wraps around the portion without the TAB electrode by applying pressure. Also, a very small number of adhesives also wrap around the recesses of the TAB electrode. TAB
The convex portion of the electrode is pressed against the transparent electrode 12 by being pressed. Through the above steps, the transparent electrode 12 and the TAB 20 can be mounted without using the anisotropic conductive film or the anisotropic conductive paste used in the conventional mounting. Even if it is small, it can be mounted.

[0008] 2. FIG. 3 shows another example of the TAB-mounted liquid crystal display device of the present invention. This TAB-mounted liquid crystal display element uses a photo-curing adhesive instead of the thermosetting adhesive in FIGS. It is desirable that the photo-curable adhesive has a viscosity as small as possible.
Those having about 10 to 1000 cP are preferred. Examples of such an adhesive include XNR54 manufactured by Ciba-Geigy.
91, which has a viscosity of 420 cP and cures with ultraviolet light.

3. With reference to FIGS. 4 and 5, a method of mounting TAB on the liquid crystal display device of the present invention will be described. (1) As shown in FIG. 4, a light-curing adhesive 32 is applied to a lead-out portion of a transparent electrode 12 to be mounted, and is irradiated with light to form a TA.
B is implemented. If a dispenser or the like is used when applying, the adhesive is not applied more than necessary.
Positioning of the lead portion of the transparent electrode 12 and the TAB electrode 22 is performed. Generally, both electrodes are aligned by applying alignment marks to both and aligning them. A light 3 having a predetermined wavelength for curing the light-curing adhesive 32 while pressing the bonding portion.
3 and 34 are irradiated. It is necessary to use a pressing member having high transparency at the wavelength of light to be irradiated. The aforementioned XNR54
When 91 is used as the adhesive, it is desirable to use a member having a high transmittance of ultraviolet light, such as synthetic quartz, as the pressing member. Unless the viscosity of the adhesive 32 is extremely large,
By pressurizing, it wraps around the portion without the TAB electrode 22. Also, a very small number of the adhesives 32 wrap around the recessed portions of the roughened TAB electrode 22. The convex portion of the TAB electrode 22 is pressed against the transparent electrode 12 by being pressed. Through the above steps, the transparent electrode 12 and the TAB 20 can be mounted without using the anisotropic conductive film or the anisotropic conductive paste used in the conventional mounting, and both the electrode pitch of the transparent electrode and the electrode pitch of the TAB can be reduced. Even if it is small, it can be mounted. The unevenness of the electrode surface of the TAB mounted on the transparent electrode of the liquid crystal panel can be formed by, for example, a paper file as described above, but it is preferable to roughen as finely as possible. The adhesive 32 is also desirably as viscous as possible. (2) The one shown in FIG. 5 is performed by applying a thermosetting adhesive 36 to the lead-out portion of the transparent electrode 12 to be mounted.
The TAB is mounted on the liquid crystal display device in the same manner as shown in FIG.

[0010] 4. As shown in FIG. 6, the substrate 11 of the liquid crystal panel and the TAB are connected with a reinforcing adhesive or reinforcing tape 3.
8 may be fixed. The configuration as shown in this figure is particularly effective when the bonding location is concentrated at the end of the TAB and the peel strength at the bonding location is low. In FIG. 6, although it is described as if there is a gap between the surface of the TAB electrode 22 and the transparent electrode 12, this is for emphasizing that the adhesive 37 permeates into the concave portion between the electrodes. In the description, actually, the two electrodes are in contact with each other without any gap at the convex portion.

As another embodiment of the present invention, a TAB mounting liquid crystal display device or a method of mounting a TAB on a liquid crystal display device includes a method using a conductive paste. TAB mounted on the transparent electrode 12 of the liquid crystal panel 10 shown in each of the drawings.
The surface of the electrode 20 is formed with concavities and convexities, and a thin conductive paste is applied to the electrode portion of the TAB before mounting the pole and the TAB. The conductive paste is not an anisotropic conductive paste, but is, for example, a conductive resin such as a silver paste or a nickel paste. This conductive paste is applied to the TAB electrode portion as follows. That is, as this application method, for example, the conductive paste is spread evenly and thinly on a flat substrate. It may be spread by spin coating or may be spread by a roller. Next, the electrode portion of TAB is pressed on the thinly spread conductive paste to apply the conductive paste to the electrode portion. The TAB coated with the conductive paste is pressed against the transparent electrode of the liquid crystal panel. By previously attaching the conductive paste to the electrode surface, the connection resistance value after bonding can be kept low. The unevenness on the electrode surface can be formed in the same manner as in the case where the adhesive is used.

[0012]

[Effect] Anisotropic conductive film (or anisotropic conductive paste)
A TAB-mounted liquid crystal display device was obtained without using a liquid crystal display device, in which poor connection between the transparent electrode of the liquid crystal display device and the TAB electrode was reduced, the peel strength of the two electrodes was increased, and the connection resistance was reduced.

[Brief description of the drawings]

FIG. 1 is a schematic plan view of a TAB-mounted liquid crystal display device of the present invention.

FIG. 2 is an enlarged view of a bonding portion of FIG.

FIG. 3 is a diagram in a case where a photocurable adhesive is used as the adhesive in FIG.

FIG. 4 is an enlarged schematic cross-sectional view of a bonding portion of FIG. 3;

FIG. 5 is a diagram when a thermosetting adhesive is used as the adhesive in FIG.

FIG. 6 is a schematic cross-sectional view of a TAB-mounted liquid crystal display element in which a substrate end and a TAB are bonded or taped.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Liquid crystal panel 11 Panel board 12 Transparent electrode (drawing part) 20 TAB 21 TAB board 22 Copper foil (surface roughened) 23 Thermosetting adhesive application part 31 Light curing adhesive application part 32 Light curing type Adhesive 33 Light irradiation 34 Light irradiation 35 TAB IC 36 Thermosetting adhesive 37 Adhesive (thermosetting or photocuring adhesive) 38 Reinforcing adhesive or reinforcing tape

Claims (5)

[Claims] 1. A liquid crystal display device comprising a substrate having a pair of transparent electrodes sandwiching liquid crystal molecules and having a TAB mounted thereon, the substrate being formed at predetermined intervals on a TAB surface,
A tab (hereinafter, also referred to as TAB) mounted liquid crystal display element, wherein an electrode having irregularities on its surface and a transparent electrode of the liquid crystal display element are joined and electrically connected by a curable adhesive. 2. The TAB-mounted liquid crystal display element according to claim 1, wherein the curable adhesive is a light curable adhesive or a thermosetting adhesive. 3. A liquid crystal display device comprising a substrate having a pair of transparent electrodes sandwiching liquid crystal molecules and having a TAB mounted thereon, the substrate being formed at predetermined intervals on the TAB surface,
A TAB-mounted liquid crystal display device, characterized by joining and electrically connecting an electrode having irregularities on its surface and a conductive paste adhered on the irregular surface to a transparent electrode of the liquid crystal display device. 4. A TAB-mounted liquid crystal display device according to claim 1, wherein the TAB is adhered or taped to the substrate end of the TAB-mounted liquid crystal display device. 5. Formed at a predetermined interval on the TAB surface,
A TAB electrode having irregularities on its surface is added to a predetermined position of a transparent electrode of a liquid crystal display device in which a substrate having a pair of transparent electrodes sandwiches liquid crystal molecules to such an extent that the positions of the two electrodes do not shift. A method of mounting a liquid crystal display element and a TAB, comprising applying a light-curing or thermosetting adhesive to the TAB after pressing and joining, and curing the TAB with light.