JP2959641B2 - Liquid crystal display - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a liquid crystal display device comprising a flexible film substrate and a liquid crystal display device comprising a driver for driving the same.

[Conventional technology]

In recent years, demands for a small, thin, lightweight, and high display capacity liquid crystal display device have been rapidly increasing. As a substrate for a liquid crystal, a flexible film substrate made of polyester, polycarbonate, polyethersulfone or the like having a thickness of about 100 μm instead of glass has been attracting attention. This is because the liquid crystal display element can be made thinner and lighter, and has advantages such as easy processing and low cost.

On the other hand, as a technical problem for achieving miniaturization and high display capacity, there is a high-density mounting of a driving driver. Drive LS
This high density can be achieved by mounting I in a bare chip state. The TAB method, in which an LSI bare chip is directly mounted on a tape carrier, has been put to practical use at the mass production level. Recently, attention has been paid to a method of mounting an LSI bare chip directly on a glass liquid crystal substrate (COG). In particular, when using a micro-bump method that does not rely on alloying methods such as soldering and wire bonding to connect the terminals of the LSI chip to the electrodes on the liquid crystal substrate, surface mounting with an electrode pitch of 100 μm or less is possible and high display It has received the most attention as a packaging technology for increasing capacitance (Nikkei Microdevices, July 1989, pp. 41-65).

Conventionally, in the LSI chip direct mounting method, for example, in the case of COG, an output power group 16 connected to a display electrode and connected to a chip output terminal, and an input lead-in electrode group 17 connected to a chip input terminal as shown in FIG. Further, a common electrode (bus line) 18 for connecting these lead-in electrode groups to each LSI chip 15 is formed. The lead-in electrode group 17 and the common electrode 18 have a laminated structure in which a transparent electrode is metallized by a method such as electroless plating in order to reduce the line resistance.

In the chip direct mounting method, a method of forming a common electrode on an external circuit board without providing the common electrode on a liquid crystal substrate has also been considered. FIG. 6 shows an example in which a lead-in electrode group 17 connected to an input terminal of an LSI chip 15 formed on a liquid crystal substrate is formed by an FPC.
This is a method of connecting to a common electrode 18 on an external substrate via a. JP-A-62-15586 describes a method of connecting a common electrode and a lead-in electrode on an external circuit board by using a conductive paste.

[Problems to be solved by the invention]

However, the prior art has the following problems.

When a common electrode portion is provided on a liquid crystal substrate on which an LSI chip is mounted as shown in FIG. 5, it is said that the use area of the liquid crystal substrate increases because the area occupied by the common electrode portion increases. There are drawbacks. In addition, it is necessary to laminate the input terminal electrode group and the common electrode by using some method. In the case of a glass substrate, cross wiring can be performed using wire bonding. However, in the case of using a flexible film substrate as a liquid crystal substrate, another method must be used because the substrate itself has low heat resistance. Further, the method of FIG. 5 is extremely costly because the surface of the transparent electrode is metallized. In particular, metallization of a transparent electrode formed on a flexible film is difficult to selectively deposit metal on the electrode by an electroless plating method like a glass substrate, so the metallization process is more costly and complicated than glass. become.

In the method shown in FIG. 6, since the connection between the input electrode and the common electrode is made via the FPC, there is a disadvantage that the number of parts and the number of connection steps are increased. Further, since the liquid crystal panel, the FPC, and the common electrode substrate are composed of three types, a support member and the like are further required in order to form a unit as a liquid crystal display device.

In the method disclosed in Japanese Patent Application Laid-Open No. Sho 62-15586, a double-sided wiring board having through holes needs to be newly formed, which increases the cost.

The present invention relates to a liquid crystal display device comprising a liquid crystal cell having a transparent electrode on the inner side and a liquid crystal cell sandwiched between a pair of upper and lower flexible film substrates which have been subjected to an alignment treatment, and a polarizing plate disposed above and below the liquid crystal cell. In a liquid crystal display device comprising a driving driver for driving an element, a common electrode (bus line) wiring for connecting a lead-in electrode group for inputting to the driving driver between the drivers with a minimum mounting area and metallizing. It is aimed at realizing low cost and low number of processes without performing.

[Means for solving the problem]

In order to achieve the above object, the liquid crystal display device of the present invention comprises:
A group of lead-in electrodes for inputting to a driver for driving printed with at least one layer of conductive resin paint is formed on a flexible film substrate constituting a liquid crystal display element, and at least one layer of at least one layer is formed on a separate flexible film substrate. A common electrode (bus line) group printed with a conductive resin paint is formed, and an insulating adhesive layer printed with an insulating resin paint is formed above the electrode group on one of the substrates, and both substrates form a conductive layer. It is characterized in that it is thermocompression-bonded.

[Action]

In the present invention, a driver input lead-in electrode group printed and formed on a flexible liquid crystal display element film substrate with a conductive resin paint, and a common electrode printed and formed with a conductive resin paint on a separate flexible film substrate are provided. Conduction is provided by providing a conductive layer at the required location, printing an insulating resin paint on the upper part of one electrode group, and thermocompression bonding both substrates, so that the common electrode wiring can be In addition, the cost, the number of parts, and the number of steps can be reduced without performing metallization by electroless plating or the like.

〔Example〕

 Hereinafter, the present invention will be described in detail based on examples.

FIG. 1 is a perspective view of this embodiment of the present invention, wherein 1 is a display area, 2 is a lower substrate made of a flexible film on which an LSI chip 5 is mounted, 3 is an upper substrate, and 4 is a common substrate. A substrate made of a flexible film on which electrodes 8 are printed, 6 is an output electrode group connected to the display electrode and connected to the output terminal of the LSI chip 5, and 7 is a lead-in electrode group connected to the input terminal of the LSI chip 5 is there. 2 is a sectional view taken along line AA of FIG. 1, FIGS. 3 (a) and 3 (b) are detailed views of the lead-in electrode group 7 on the lower substrate 2, and FIGS. 4 (a), (b) and (C) is a detailed view of the substrate 4 on which the common electrode 8 is printed.

In the present embodiment, as shown in FIG. 3, a pattern of the transparent electrode 3-B is first formed on the substrate 3-A by photolithography, and the drawn electrode group 7 is formed on the formed transparent electrode 3-B as shown in FIG. Conductive resin paint 3 by screen printing
-C is printed. In the present embodiment, a mixture of Ag and carbon was used as the conductive member. Common electrode 8
As shown in FIG. 4, a transparent resin coating 4-C containing Ag / carbon is first printed on a transparent electrode 4-B formed on a substrate 4-A by photolithography, and then the common electrode is printed. The conductive layer 4-D is formed by a screen printing method at a position connected to the lead-in electrode group 7 in FIG. In this embodiment, Ag is used as the conductive layer 4-D.
/ Carbon blend A dispersion of metal particles and filler in a resin coating was used. Next, an insulating adhesive layer 4-E made of a thermosetting resin paint is printed on the entire surface of the common electrode 8. After the substrate 4 on which the common electrode 8 is formed is superposed and aligned on the lead-in electrode group 7 on the lower substrate 2 and then heat-pressed with a heat sealer, the conduction in the up-down direction becomes conductive layer 4-D containing metal filler. Can be obtained only at the portion where the is formed.

In this embodiment, the flexible film substrate on which the common electrode is formed is made as a separate part on the process or on the unit.
For example, after a common electrode is formed in a blank portion on the lower substrate by the above-described method, this portion can be separated from the lower substrate and used.

In this embodiment, the LSI chip is mounted on the lower substrate.However, even when TAB is used, the configuration of the lead-in electrode, the common electrode, and the connection method may be adapted as in this embodiment. Of course it is possible.

[Effects of the Invention] According to the present invention, a lead-in electrode group for driving driver input printed with at least one layer of conductive resin paint is formed on a flexible film substrate constituting a liquid crystal display element,
A common electrode (bus line) group printed with at least one conductive resin paint is formed on a separate flexible film substrate, and an insulating adhesive layer printed with an insulating resin paint is formed on the electrode group on one substrate. Since both substrates are formed and both substrates are thermocompression-bonded via a conductive layer, the common electrode wiring can be realized in a minimum mounting area and at low cost and with a small number of steps without performing metallization by conventional plating or the like.

Further, since the electrodes are formed by printing a conductive resin paint, disconnection can be reduced by external stress such as bending of the substrate.

[Brief description of the drawings]

FIG. 1 is a perspective view of an embodiment of the present invention, and FIG.
3A and 3B are a plan view and a sectional view, respectively, showing in detail a lead-in electrode group on the lower substrate;
4 (a), (b) and (c) are a plan view, a side sectional view and a longitudinal sectional view, respectively, showing details of a substrate on which a common electrode is printed, and FIGS. 5 and 6 are conventional LSI chips. FIG. 4 is an explanatory diagram of a mounting method. DESCRIPTION OF SYMBOLS 1 ... Display area 2 ... Lower substrate 3 ... Upper substrate 4 ... Common electrode substrate 5 ... LSI chip 6 ... Output electrode group 7 ... Lead-in electrode group 8 ... Common electrode

Continuation of the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) G02F 1/1345 H05K 3/32 G09F 9/00

Claims (3)

(57) [Claims] 1. A liquid crystal display device comprising a liquid crystal cell having a transparent electrode inside and a liquid crystal layer sandwiched between a pair of upper and lower flexible film substrates which have been subjected to an alignment treatment. In a liquid crystal display device comprising a driving driver for driving a display element, a group of lead-in electrodes for inputting to a driving driver printed with at least one layer of a conductive resin is formed on the flexible film substrate. A common electrode group printed with at least one layer of conductive resin is formed on a flexible film substrate, and an insulating layer printed with an insulating paint is formed on the electrode group of one substrate, and both substrates are electrically conductive. A liquid crystal display device which is thermocompression bonded via a layer. 2. The liquid crystal display device according to claim 1, wherein the driving driver is a tape carrier (TAB) on which the driving LSI chip is directly mounted. 3. The liquid crystal display device according to claim 1, wherein the driving driver has a driving LSI chip directly mounted on an electrode formed of the conductive resin.