JPH04184322A - Liquid crystal display device - Google Patents

Abstract

PURPOSE:To form common electrode wirings with a min. packaging area at a low cost and the low number of stages without metallization by forming leading-in electrodes for inputting to drivers on a film substrate, forming a common electrode group on another film substrate, forming an insulation adhesive layer in the upper part of the electrode groups of the one substrate and thermocompression molding the two substrates via a conductive layer. CONSTITUTION:The patterns of transparent electrodes 3-B are formed on the substrate 3-A and a conductive resin coating material 3-C is printed thereon to constitute the leading-in electrode groups 7. The transparent electrodes 4-B are formed on the substrate 4-A and a conductive resin coating material 4-C is printed thereon; further, a conductive layer 4-D is formed, by which the common electrodes 8 are constituted. An insulation adhesive layer 4-E is printed over the entire part of the common electrodes 8, 4-D. The substrate 4 formed with the common electrodes 8 is superposed and registered on the leading-in electrode groups 7 on the lower substrate 2. The conduction in a vertical direction is taken only at the point formed with the conductive layer 4-D contg. metallic fillers when these substrates are thermocompression bonded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a liquid crystal display device comprising a liquid crystal display element made of a flexible film substrate and a driver for driving the liquid crystal display element.

[Conventional technology]

In recent years, there has been a rapid increase in demand for liquid crystal display devices to be smaller, thinner, lighter, and higher in display capacity. Instead of glass, flexible film substrates made of polyester, polycarbonate, polyether sulfon, etc. with a thickness of about 100 ps are attracting attention as substrates for liquid crystals. This is because the liquid crystal display element can be made thinner and lighter, and has advantages such as ease of processing and cost reduction.

On the other hand, a technical challenge for achieving miniaturization and high display capacity is high-density packaging of drivers. Drive LS
This high density can be achieved by mounting I as a pair of chips. The TAB method, in which paired LSI chips are directly mounted on a tape carrier, has been put into practical use at the mass production level. Recently, a method of directly mounting an LSI pair chip on a glass liquid crystal substrate (COG) has been attracting attention.

In particular, when using a microbump method that does not rely on alloying methods such as soldering or wire bonding to connect the terminals of the LSI chip and the electrodes on the liquid crystal substrate, the electrode pitch is 100.
It has become possible to perform surface mounting in micrometers or less, and is attracting the most attention as a mounting technology for increasing display capacity (Nikkei Microdevices, July 1989, p. 41-65).

Conventionally, in the LSI chip direct mounting method, for example, in the case of COG, as shown in FIG. , and each L
A common electrode (pass line) 18 is formed that connects these lead-in electrode groups connected to the SI chip 15. The lead-in electrode group 17 and the common electrode 18 have a laminated structure in which transparent electrodes are metallized by electroless plating or the like in order to reduce line resistance.

In the chip direct mounting method, a method is being considered in which the common electrode is not provided on the liquid crystal substrate but is formed on an external circuit board. FIG. 6 shows one example of this, in which a lead-in electrode group 17 formed on a liquid crystal substrate and connected to an input terminal of an LSI chip 15 is connected to an F.
This method connects to the common electrode 18 on the external board via a PC. Further, Japanese Patent Application Laid-Open No. 15586/1986 describes a method of connecting a common electrode and a lead-in electrode on an external circuit board using a conductive paste.

[Problem to be solved by the invention]

However, the prior art has the following problems.

If a common electrode section is provided on a liquid crystal substrate on which an LSI chip is mounted as shown in Fig. 5, the area occupied by the common electrode section becomes large, so the area used for the liquid crystal substrate becomes large. There are drawbacks. Further, it becomes necessary to use some method to stack and cross-wire the input terminal electrode group and the common electrode. In the case of a glass substrate, cross wiring can be performed using wire bonding, but when a flexible film substrate is used as a liquid crystal substrate, other methods must be used because the heat resistance of the substrate itself is low. Furthermore, in the method shown in FIG. 5, the surface of the transparent electrode is metallized, resulting in a very high cost. In particular, metallizing transparent electrodes formed on flexible films is difficult to selectively deposit metal on the electrodes using electroless plating, unlike glass substrates, so the metallization process is more costly and complicated than for glass. become.

In the method shown in FIG. 6, since the input electrode and the common electrode are connected via the FPC, there are drawbacks such as an increase in the number of parts and the number of connection steps. Furthermore, since it consists of three types of configurations, including a liquid crystal panel and an FPC5 common electrode substrate, supporting members and the like are additionally required in order to unitize it as a liquid crystal display device.

The method disclosed in Japanese Unexamined Patent Publication No. 62-15586 requires a new double-sided wiring board having through holes, resulting in high costs.

The present invention relates to a liquid crystal display element comprising a liquid crystal cell having a transparent electrode inside and a liquid crystal layer sandwiched between a pair of upper and lower aligned flexible film substrates, and polarizing plates disposed on each of the upper and lower sides of the liquid crystal cell, and the liquid crystal display. In a liquid crystal display device consisting of a driving driver that drives an element, common electrode (pass line) wiring for connecting a group of lead-in electrodes for inputting to the driving driver between each driver has a minimum mounting area and is metallized. The aim is to achieve this at low cost and with a low number of steps without having to do anything.

[Means to solve the problem]

In order to achieve the above object, the liquid crystal display device of the present invention includes a group of lead-in electrodes for inputting to a driving driver printed with at least one layer of conductive resin paint on a flexible film substrate constituting the liquid crystal display element. A group of common electrodes (pass lines) printed with at least one layer of conductive resin paint is formed on separate flexible film substrates, and an insulating layer is formed with an insulating resin paint printed on the top of the electrode group of one substrate. Features [Function] Features: An adhesive layer is formed and both substrates are thermocompression bonded via a conductive layer. In the present invention, a conductive resin paint is applied to a flexible liquid crystal display element film substrate. A conductive layer is provided at the required location and the upper part of one electrode group is connected to the print-formed driver manual lead-in electrode group and the common electrode printed and formed with conductive resin paint on a separate flexible film substrate. This is done by printing an insulating resin paint on the board and thermocompressing the two boards, which eliminates the need to metalize the transparent electrodes and minimizes the mounting area, regardless of whether a flexible film board is used. Furthermore, the number of parts and processes can be reduced.

〔Example〕

The present invention will be described in detail below based on examples.

FIG. 1 is a perspective view of this embodiment of the present invention, in which 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 A substrate made of a flexible film with electrodes 8 printed on it, 6 a group of output electrodes connected to the display electrodes and connected to the output terminals of the LSI chip 5, and 7 a group of lead-in electrodes connected to the input terminals of the LSI chip 5. be. 2 is a sectional view taken along line A--A in FIG. 1, FIGS. 3(a) and 3(b) are detailed views of the lead-in electrode group 7 on the lower substrate 2, and FIG. 4(a).

(b) and (c) are detailed views of the substrate 4 on which the common electrode 8 is printed.

In this embodiment, as shown in FIG. 3, the lead-in electrode group 7 is formed by first forming a pattern of transparent electrodes 3-H on a substrate 3-A by photolithography, and then forming a pattern of transparent electrodes 3-H on the formed transparent electrodes 3-B. Conductive resin paint 3- by screen printing method
Configure by printing C.

In this example, a mixture of Ag and carbon was used as the conductive member. As shown in FIG. 4, the common electrode 8 is a transparent electrode 4-A formed on a substrate 4-A by photolithography.
First, a conductive resin paint 4-C containing carbon is printed on B, and then a conductive layer 4-C is printed by screen printing on the common electrode at the location where it will be connected to the lead-in electrode group 7 shown in FIG. Constructed by forming D. In this example, a layer in which Ag/carbon blend metal particle filler was dispersed in a resin paint was used as the conductive layer 4-D. Next, an insulating adhesive layer 4- made of thermosetting resin paint is applied to the entire surface of the common electrode 8.
Print E. The substrate 4 on which the common electrode 8 is formed in this way
After superimposing and positioning on the lead-in electrode group 7 on the lower substrate 2, the electrodes are heated and pressed using a heat sealer, so that vertical conduction can be established only at the location where the metal filler-containing conductive layer 4-D is formed.

In this example, the flexible film substrate on which the common electrode was formed was made as a separate part in the process or on the unit. For example, after forming the common electrode in the margin area on the lower substrate by the above method, this part It is also possible to use it by separating it from the lower substrate.

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

〔Effect of the invention〕

According to the present invention, a pull-in electrode group for human power of a driving driver is formed by printing at least one layer of conductive resin paint on a flexible film substrate constituting a liquid crystal display element, and is formed on a separate flexible film substrate. forming a group of common electrodes (pass lines) printed with at least one layer of conductive resin paint,
An insulating adhesive layer printed with an insulating resin paint is formed on the top of the electrode group on one board, and both boards are bonded together by thermocompression via a conductive layer, allowing the common electrode wiring to be formed with a minimum mounting area and using conventional plating. It can be realized at low cost and with a low number of steps without metalizing.

Furthermore, since the electrode is constructed by printing conductive resin paint, disconnection due to external stress such as bending of the substrate can be reduced.

[Brief explanation of the drawing]

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

Claims (3)

[Claims] (1) A liquid crystal display element in which a liquid crystal cell has a transparent electrode inside and a liquid crystal layer is sandwiched between a pair of upper and lower aligned flexible film substrates, and polarizing plates are disposed on each of the upper and lower sides of the liquid crystal cell, and the liquid crystal display element In a liquid crystal display device comprising a driving driver for driving, a group of lead-in electrodes for inputting to the driving driver printed with at least one layer of conductive resin is formed on the flexible film substrate, and a separate flexible film substrate is formed. A common electrode group printed with at least one layer of conductive resin is formed on a film substrate, an insulating layer printed with insulating paint is formed on top of the electrode group of one substrate, and both substrates have a conductive layer. 1. A liquid crystal display device characterized in that the device is bonded by thermocompression through a wire. (2) The liquid crystal display device according to claim 1, wherein the driving driver is a tape carrier (TAB) on which a 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 mounted directly on an electrode formed of the conductive resin.