JP3349365B2 - Liquid crystal display device and method of manufacturing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plastic liquid crystal display device using a plastic electrode substrate, and more particularly to a liquid crystal display device in which the adhesive force between an electrode substrate and a driving circuit substrate is reinforced, and a method of manufacturing the same. It is about.

[0002]

2. Description of the Related Art In recent years, a plastic liquid crystal display device using a plastic film or a plastic sheet as an electrode substrate has attracted attention from the viewpoint of reducing the thickness and weight of the liquid crystal display device, and has been used in the field of small displays such as calculators and IC cards. Has been put to practical use.

In a plastic liquid crystal display device, an external connection terminal of an electrode substrate and a connection terminal of a drive circuit board are thermocompression bonded via an anisotropic conductive film or a heat seal connector or the like, so that the liquid crystal display panel is connected to the drive circuit. Are electrically connected, and the electrode substrate and the drive circuit substrate are bonded.

[0004]

However, when the plastic liquid crystal display device is placed in an environment where the temperature changes drastically,
Due to the difference in the coefficient of thermal expansion of the substrate material between the electrode substrate and the drive circuit substrate, stress may be applied to the connection part, or excessive force may be applied to the connection part from the outside due to handling of unit assembly etc. Poor connection such as peeling or floating of an isotropic conductive film or a heat seal connector occurs.

[0005] This connection failure is caused by TAB (Tape-Au).
driver L of tomed-Bonding type
Various types of connection, such as connection through an anisotropic conductive film on SI, or pattern printing of conductive resin, and connection with a heat seal connector in which terminal particles are printed with ink in which conductive particles are uniformly dispersed in thermosetting insulating resin In the thermo-compression bonding method described above.

[0006] The poor connection results from insufficient bonding strength between the electrode substrate and the drive circuit substrate. In other words, when thermocompression bonding of an electrode substrate made of plastic and a drive circuit board is performed at a lower temperature, a lower pressure, and a shorter time than in the case of an electrode substrate made of glass,
It is difficult to secure the adhesive strength.

More specifically, a thermosetting resin is used for the adhesive such as the anisotropic conductive film and the heat seal connector used for thermocompression bonding, and the thermocompression bonding temperature is equal to or higher than the curing temperature of the adhesive. The thermocompression bonding time needs to be set to a time that can secure the heat capacity required for the polymerization of the adhesive.

Further, regarding the pressing force in thermocompression bonding,
There is a problem that the external connection terminals of the plastic electrode substrate are broken due to cracks, and the pressing force cannot be increased unnecessarily. Therefore, it is difficult to perform thermocompression bonding with high adhesive strength.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described conventional problems. Even when a stress is applied to a connection portion between an electrode substrate and a drive circuit board, the connection portion may be peeled off or removed. It is an object of the present invention to provide a liquid crystal display device that does not cause a connection failure such as floating and a method of manufacturing the same.

[0010]

According to a first aspect of the present invention, there is provided a liquid crystal display device comprising: an external connection terminal of an electrode substrate made of plastic; and a connection terminal of a drive circuit substrate. Connected by thermocompression bonding via an anisotropic conductive film or a heat seal connector,
In a liquid crystal display device in which the adhesive force between the electrode substrate and the drive circuit substrate is reinforced, the adhesive force is reinforced by welding the electrode substrate and the drive circuit substrate. .

According to a second aspect of the present invention, there is provided a method of manufacturing a liquid crystal display device, comprising: an external connection terminal of an electrode substrate made of plastic;
A method for manufacturing a liquid crystal display device in which connection terminals of a drive circuit board are connected by thermocompression bonding via an anisotropic conductive film or a heat seal connector to reinforce the adhesive force between the electrode board and the drive circuit board Wherein the electrode substrate and the drive circuit substrate are welded by using ultrasonic waves to reinforce the adhesive force.

According to the liquid crystal display device of the present invention, since the adhesive force is reinforced by welding the electrode substrate and the drive circuit substrate, the thermocompression bonding conditions are such that good electrical connection can be obtained. Then, low-temperature, low-pressure, and short-time thermocompression bonding suitable for an electrode substrate made of plastic can be performed, and the reliability of electrical connection is improved.

Further, according to the method of manufacturing a liquid crystal display device of the present invention, the adhesive force is reinforced by welding the electrode substrate and the drive circuit substrate by using ultrasonic waves, thereby enhancing the adhesive force. Because it can be performed in, without adversely affecting the electrical connection portion, the thermocompression bonding conditions may be such that a good electrical connection can be obtained, low temperature, low pressure and suitable for the electrode substrate made of plastic Short-time thermocompression bonding becomes possible, and the reliability of electrical connection is improved.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a cross-sectional view illustrating a method for manufacturing a liquid crystal display device according to the present invention, and FIG. 2 is a plan view illustrating a liquid crystal display device according to the present invention.

[0015] As shown in FIG. 1, a pair of electrode substrates 1 made of plastic, subjected to gas barrier coating due SiO _X, etc. on the entire surface, a film of ITO by sputtering, a transparent electrode for display by photolithography 2 and external connection terminals 3 are formed.

Further, an alignment film 4 made of polyimide or the like is formed by an offset printing method or a flexographic printing method, and is subjected to an alignment treatment by a rubbing method or the like, so that the pair of electrode substrates 1 is interposed via a spacer 5 and a sealing material 6. to paste together.

Then, the liquid crystal display panel is divided, the liquid crystal material 7 is injected, and the polarizing plate 8 is attached to obtain a liquid crystal display panel.

Next, the connection terminals 11 and the external connection terminals 3 of the drive circuit board 10 on which the driver LSI 9 is mounted are replaced with a tape-shaped anisotropic conductive film in which conductive particles 13 are uniformly dispersed in a thermosetting resin 12. The thermocompression bonding is carried out by a crimping head 15 via 14 to electrically connect and bond the electrode substrate 1 and the drive circuit board 10.

As the conductive particles 13, metal particles or particles obtained by plating metal on resin beads can be used, and are not particularly limited.

The connection terminals 11 may be formed by etching a copper foil, forming a pattern, and performing gold plating or tin plating, and is not particularly limited.

The conditions for thermocompression bonding may be a temperature, time and pressure at which the external connection terminal 3 and the connection terminal 11 can be electrically connected in a good condition. It is not necessary to consider the adhesive strength.

Next, the electrode substrate 1 and the drive circuit substrate 10 are welded by applying ultrasonic waves by the ultrasonic welding head 16,
A liquid crystal display device is obtained with improved adhesive strength.

As shown in FIG. 2, the welding portion 17 by ultrasonic waves is formed in a pinpoint circular shape on the outer portions at both ends of the external connection terminal 3 and the connection terminal 11. If it is possible to contribute to the improvement of the adhesive strength with the drive circuit board 10, the welding portion 17 may be provided at a plurality of positions, and the shape may be other than the circular shape.

[0024]

As described above, according to the liquid crystal display device of the present invention, the adhesion is reinforced by welding the electrode substrate and the drive circuit substrate, so that the thermocompression bonding conditions are good. It is possible to obtain a plastic liquid crystal display device with high reliability in electrical connection, which enables low-temperature, low-pressure and short-time thermocompression bonding suitable for an electrode substrate made of plastic. Can be.

Further, according to the method of manufacturing a liquid crystal display device of the present invention, the adhesion is strengthened by welding the electrode substrate and the drive circuit substrate by using ultrasonic waves, thereby enhancing the adhesion. Because it can be performed in, without adversely affecting the electrical connection portion, the thermocompression bonding conditions may be such that a good electrical connection can be obtained, low temperature, low pressure and suitable for the electrode substrate made of plastic Thermocompression bonding can be performed in a short time, and a plastic liquid crystal display device having high reliability of electrical connection can be obtained.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a method for manufacturing a liquid crystal display device according to the present invention.

FIG. 2 is a plan view illustrating a liquid crystal display device according to the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 electrode substrate 2 display transparent electrode 3 external connection terminal 4 alignment film 5 spacer 6 sealing material 7 liquid crystal material 8 polarizing plate 9 driver LSI 10 drive circuit board 11 connection terminal 12 thermosetting resin 13 conductive particles 14 anisotropic conductive film 15 Crimping head 16 Ultrasonic welding head 17 Welding part

Claims (2)

(57) [Claims] An external connection terminal of an electrode substrate made of plastic and a connection terminal of a drive circuit substrate are connected by thermocompression bonding via an anisotropic conductive film or a heat seal connector, and are connected to the electrode substrate. A liquid crystal display device in which the adhesive strength with the drive circuit board is reinforced, wherein the electrode board and the drive circuit board are reinforced by welding. 2. An external connection terminal of an electrode substrate made of plastic and a connection terminal of a drive circuit board are connected by thermocompression bonding via an anisotropic conductive film or a heat seal connector. In a method of manufacturing a liquid crystal display device that reinforces an adhesive force with a drive circuit board, the liquid crystal display device is characterized in that the electrode substrate and the drive circuit board are welded using ultrasonic waves to reinforce the adhesive force. A method for manufacturing a display device.