JP3059744B2 - Liquid crystal display - Google Patents

Description

The present invention relates to a liquid crystal display device using a liquid crystal cell in which a flexible substrate for driving is electrically and mechanically connected.

(B) Conventional technology In recent years, liquid crystal display devices have been disclosed in
As described in JP-A-225120, a driving means is arranged near a liquid crystal cell, and the wiring of the driving means is electrically and mechanically connected using an anisotropic conductive film. However, in this publication, reproduction was not successful because only one kind of anisotropic conductive film was used. If an anisotropic conductive film containing hard metal particles is used in the first compression bonding, the metal particles are hard and the contact area is small, and a connection failure due to a positional shift between the terminal portion and the conductive portion is likely to occur. In addition, if an anisotropic conductive film containing soft metal particles is used at the time of the first press-bonding, it is soft and hardly causes poor connection. However, if the connection is broken and playback starts,
At the time of the second press bonding, the previous anisotropic conductive film remains, and the remaining portion hinders the pressing of the metal particles, and the electrical and mechanical connections are not sufficient. This is the first disadvantage.

Next, for example, when a long flexible substrate composed of 160 terminals and a short flexible substrate composed of 80 terminals are used for one liquid crystal cell, crimping is not successful. because,
A flexible substrate having a long crimping portion has a strong restoring force, and the pressing force is easily dispersed throughout the crimping portion, so that the hard metal particles are easily peeled off in a small contact area, so that the hard metal particles cannot be crimped well. In addition, when soft metal particles are pressed against a short flexible substrate, the conductive anisotropy is impaired such that the metal particles are excessively crushed and a leakage current occurs between adjacent metal particles. This is the second disadvantage.

Further, when it is desired to use a hard flexible substrate and a soft flexible substrate for one liquid crystal cell, for example, an anisotropic conductive film having hard metal particles on the hard flexible substrate Does not work. Because the flexible substrate is hard, the restoring force to warp is strong, and the restoring force cannot be absorbed by the narrow contact area of the hard metal particles,
We cannot crimp well. In addition, when an anisotropic conductive film having soft metal particles is pressed on a soft flexible substrate, the metal particles are so soft that they are crushed too much and adjacent conductive portions leak or short-circuit. This is the third disadvantage.

(D) Means for Solving the Problems In order to solve the above problems, the present invention provides a liquid crystal cell using a substrate having a terminal portion on the surface and an anisotropic conductive film containing soft metal particles. A first flexible substrate crimped on the terminal portion, and a second flexible substrate crimped on the terminal portion via the remaining anisotropic conductive film and the anisotropic conductive film containing hard metal particles. And two flexible substrates.

The present invention also includes a flexible substrate having a long pressure-bonded portion, which is pressure-bonded onto a terminal portion of a liquid crystal cell via an anisotropic conductive film including soft metal particles, and hard metal particles. And a flexible substrate having a short crimping portion which is crimped on the terminal portion via an anisotropic conductive film.

Still further, the present invention provides a hard flexible substrate press-bonded on a terminal portion of a liquid crystal cell via an anisotropic conductive film containing soft metal particles, and an anisotropic conductive film containing hard metal particles. And a soft flexible substrate that is crimped onto the terminal portion through the substrate.

(E) Function By the above-described means, the hard metal particles penetrate the remaining portion of the previous anisotropic conductive film at the time of the second pressure bonding, and the connection of the terminal portion can be sufficiently performed.

And the length of the crimping part is different due to the above means,
Alternatively, flexible substrates having different substrate hardnesses can be electrically and mechanically connected firmly and anisotropically.

(F) Embodiment First, according to FIG. 1, FIG. 2 and FIG.
An embodiment will be described. FIG. 1 is a partial cross-sectional view of the liquid crystal display device after the first press-fitting, and FIGS. 2 and 3 are main-portion cross-sectional views of the liquid crystal display device before and after the second press (at the time of reproduction), respectively. It is. In FIG. 1, reference numeral 1 denotes a substrate made of glass or the like having a plurality of terminal portions 2 on the surface. One terminal section 2 is made of, for example, 160 terminals having a pitch of 200 μm, and there are a plurality of terminal sections 2, so that the number of terminals is 160 × integer (number).

Reference numeral 3 denotes a liquid crystal cell, and the substrate 1 having the electrode film 4 and the liquid crystal alignment film 5 is bonded at regular intervals by spacers 6,
A chiral nematic liquid crystal layer 7 is interposed therebetween, and polarizers and the like (not shown) are bonded to both outer sides of the substrate 1. The terminal portion 2 is formed by extending the electrode film 4 provided on the lower substrate 1 to the edge, and if necessary, the electrode film 4 of the upper substrate 1 is also oriented in a direction perpendicular to the plane of the drawing. To extend to the same terminal portion.

Reference numeral 8 denotes a first flexible substrate called TAB (Tape Automated Bonding Package) provided with driving means. The first flexible substrate 8 has a number of input-side lead foils 9 and output-side lead foils 10 made of tin-plated copper pieces or the like serving as terminals of the integrated circuit element 11. These lead foils 9 and 10 are held by an insulating sheet 12 made of a polyimide sheet or the like, and the vicinity of the connection point between the lead foils 9 and 10 and the integrated circuit element 11 is covered and protected by a protective resin 13.

One first flexible substrate 8 has a pitch of 200 μm, for example.
It has 60 output-side lead foils 10, and several to ten and several first flexible substrates 8 are used for one liquid crystal cell 3 according to the display capacity.

For example, the anisotropic conductive film 14 made of CP3131FT of Sony Chemical Co., Ltd. is made of soft metal particles 15 and an adhesive 16 and has a thickness before pressure bonding of about 35. Among them, the adhesive 16 is made of a thermosetting resin, the soft metal particles 15 are made of, for example, a solder made of an Sn—Pb alloy, and the particle diameter before compression is 10 to 15 μm, and has relatively small hardness.

After bonding the anisotropic conductive film 14 on the terminal portion 2
After aligning the terminal portion 2 and the output-side lead foil 10 with a TAB positioning device, crimping is performed with a TAB thermocompression device. By this crimping work, the soft metal particles 15 are pressed down,
The anisotropic conductive film 14 has a thickness of about 2 μm.

Next, the case where it is necessary to perform reproduction by causing a conduction defect such as displacement or partial peeling by the above means will be described with reference to FIG. Only the first flexible substrate 8 having poor connection is removed while applying heat using a spot heater. Then, a new second flexible substrate 17 for reproduction, which has the same configuration as the first flexible substrate 8 , is prepared. The anisotropic conductive film 14 after the first flexible substrate 14 has been removed by immersing acetone in a cotton swab is rubbed off, but the remaining portion 18 of the anisotropic conductive film 14 remains without being completely cleaned.

This is because the adhesive 16 is a thermosetting resin and is not completely dissolved in a solvent. If the adhesive 16 is a thermoplastic resin, it is completely soluble in the solvent, but a thermosetting resin having heat and moisture resistance must be used for the liquid crystal display device.

Next, an anisotropic conductive film 19 is used. This is, for example, an anisotropic conductive film 1 composed of a CPU4221 of Sony Chemical Corporation.
In 9 , a hard metal particle 20 and an adhesive 21 are formed, and the thickness before pressure bonding is about 20 μm. The adhesive 21 is made of a thermosetting resin and includes hard metal particles 20. The hard metal particles 20 are made of, for example, metal Ni, have a particle size of about 10 μm before pressure bonding, and have relatively high hardness. In addition, In, Au, or the like can be used as another material. An anisotropic conductive film 19 is adhered on the remaining portion 18 of the anisotropic conductive film.

Next, the liquid crystal display device after pressure bonding will be described with reference to FIG.
After the terminal portion 2 and the output-side lead foil 10 provided on the second flexible substrate 17 are aligned again by the TAB positioning device, they are crimped under the following crimping conditions.

Crimping conditions: Crimping temperature = 175 to 185 ° C, crimping time = 20 to 30
Second, compression pressure = 30 to 50 kgf / cm ^{2 By} this compression work, the hard metal particles 20 are hard,
It penetrates through the remaining portion of the soft metal particles 15 and the remaining portion of the adhesive 16 included in the remaining portion 18 of the anisotropic conductive film. As a result, the terminal 2
Sufficient electrical and mechanical connection between the lead foil 10 and the output side can be secured. The thickness of the anisotropic conductive film 19 after compression is about 3 μm.
m. This concludes the description of the first embodiment of the present invention.

Next, a second embodiment of the present invention will be described with reference to FIGS. FIG. 4 is a cross-sectional view of a main part of a liquid crystal display device using a relatively long flexible substrate having a crimping portion of about 50 mm. FIG. 5 is a liquid crystal display using a relatively short flexible substrate having a crimping portion of about 25 mm. It is principal part sectional drawing of a display apparatus.

In FIG. 4, reference numeral 2 denotes a terminal portion having 160 terminals with a pitch of 200 μm, for example. Reference numeral 8 denotes a first flexible substrate, which is made of the same material as that described in the first embodiment, and has a length of
It has a relatively long crimping section of 50 mm. Reference numeral 14 denotes an anisotropic conductive film, which comprises soft metal particles 15 and an adhesive 16, and is made of the same material as that shown in the first embodiment. Then, the flexible substrate 8 having a long crimping portion is crimped on the terminal portion 2 via the anisotropic conductive film 14 .

In FIG. 5, reference numeral 22 denotes a terminal portion having, for example, 80 terminals with a pitch of 200 μm. Reference numeral 23 denotes a flexible substrate having a short crimp portion, and 80 output-side lead foils 2 having a pitch of 200 μm.
4 and an insulating sheet 25. Crimp length is relatively short2
5 mm. 19 is an anisotropic conductive film. Hard metal particles 2
0 and an adhesive 21 and are made of the same material as that shown in the first embodiment.

Then, the flexible substrate 23 having a short crimping portion is crimped on the terminal portion 22 via the anisotropic conductive film 19 . By using different anisotropic conductive films for the flexible substrates having different lengths of the press-bonded portions, connection can be made without causing poor conduction or leakage current.

Similarly, a third embodiment in which flexible substrates having different hardnesses are combined with different anisotropic conductive films will be described with reference to FIGS. 6 and 7. FIG. 6 and FIG. 7 are cross-sectional views of main parts of a liquid crystal display device using a hard flexible substrate or a soft flexible substrate, respectively. In FIG. 6, reference numeral 26 denotes a hard flexible substrate, which has an insulating sheet 27 made of a polyimide sheet or the like having a thickness of 300 μm for firmly supporting 160 output-side lead foils 10 having a pitch of 200 μm. .

As a result, the hardness is increased. The anisotropic conductive film 14 and the terminal 2 are made of the same material as that shown in the first embodiment.
Then, a hard flexible substrate 26 is pressed onto the terminal portion 2 via the anisotropic conductive film 14 containing the soft metal particles 15.

In FIG. 7, a soft flexible substrate 28 is an output side lead foil.
10 has an insulating sheet 29 made of a polyimide sheet or the like having a thickness of 150 μm for the purpose of low-temperature fusion or to sufficiently increase the flexibility of the substrate. As a result, the hardness is low. Then, anisotropic conductive film 19 containing hard metal particles 20
A soft flexible substrate 28 is crimped onto the terminal portion 2 through the terminal. Thus, even if the hardness of the flexible substrates is different, reliable connection can be achieved by using an anisotropic conductive film suitable for each.

(G) Effect of the Invention According to the present invention, when it is necessary to regenerate due to a conduction defect such as displacement or partial peeling by the above-described means, the hard metal particles are removed at the second press-bonding. Through the remaining portion of the isotropic conductive film, sufficient electrical and mechanical connection between the terminal portion and the flexible substrate can be secured.

Further, by the above-described means, the flexible substrate having a long crimp portion or the rigid flexible substrate is hard and has a restoring force. The metal particles can be sufficiently and properly crushed by overcoming the restoring force. In addition, since a flexible substrate having a short crimping portion or a soft flexible substrate is soft, by combining it with hard metal particles, the metal particles are not excessively crushed even when crimped, and the adjacent conductive portion Since the members are not short-circuited, a sufficient electric and mechanical connection between the terminal portion and the flexible substrate can be secured.

[Brief description of the drawings]

FIG. 1 is a partial cross-sectional view of a liquid crystal display device after a first press bonding in the first embodiment of the present invention, and FIG. 2 is a second cross section (at the time of reproduction) in the first embodiment of the present invention. FIG. 3 is a cross-sectional view of a main part of the liquid crystal display device before crimping, FIG. 3 is a cross-sectional view of a main part of the liquid crystal display device after the second (during reproduction) crimping in the first embodiment of the present invention, and FIG. FIG. 5 is a cross-sectional view of a main part of a liquid crystal display device using a flexible substrate having a long crimp portion according to a second embodiment of the present invention. FIG. FIG. 6 is a cross-sectional view of a main part of a liquid crystal display device using a flexible substrate having a crimp portion. FIG. 6 is a cross-sectional view of a main part of a liquid crystal display device using a rigid flexible substrate according to a third embodiment of the present invention. FIG. 7 is a sectional view of a main part of a liquid crystal display device using a soft flexible substrate according to a third embodiment of the present invention. Reference numeral 1 denotes a substrate, 2 denotes a terminal portion, 3 denotes a liquid crystal cell, 8 denotes a first flexible substrate or a flexible substrate having a long crimping portion,
14 ... anisotropic conductive film containing soft metal particles, 15 ... soft metal particles, 17 ... second flexible substrate, 18 ... remainder of anisotropic conductive film, 19 ... hard Anisotropic conductive film containing metal particles, 20 hard metal particles, 22 terminal part, 23 flexible substrate having short crimped part, 26 rigid hard substrate, 28 ... Soft flexible substrate.

────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Masanori Tamura 3-201 Minamiyoshikata, Tottori City, Tottori Prefecture Tottori Sanyo Electric Co., Ltd. (72) Makoto Kasami 3-201 Minamiyoshikata, Tottori City, Tottori Prefecture Tottori Sanyo Electric Co., Ltd. (58) Field surveyed (Int.Cl. ⁷ , DB name) G02F 1/1345 H05K 3/36

Claims (3)

(57) [Claims] 1. A liquid crystal cell using a substrate having a plurality of terminal portions on its surface, and a plurality of first pressure-bonded portions on said plurality of terminal portions via an anisotropic conductive film containing soft metal particles. A flexible substrate, and an anisotropic conductive film containing the remainder of the anisotropic conductive film and hard metal particles on the terminal portion from which the first flexible substrate of the plurality of terminal portions has been removed And a second flexible substrate that is press-bonded through the liquid crystal display device. 2. A liquid crystal cell using a substrate having a terminal portion on the surface, and a flexible portion having a long pressure-bonded portion which is pressure-bonded onto the terminal portion via an anisotropic conductive film containing soft metal particles. A liquid crystal display device comprising: a flexible substrate; and a flexible substrate having a short crimped portion that is crimped on the terminal portion via an anisotropic conductive film containing hard metal particles. 3. A liquid crystal cell using a substrate having a terminal portion on its surface, a hard flexible substrate pressed onto said terminal portion via an anisotropic conductive film containing soft metal particles, A soft flexible substrate which is pressed onto the terminal portion via an anisotropic conductive film containing metal particles.