JPH07152045A - Liquid crystal display device - Google Patents

Abstract

PURPOSE:To form an insulating protective film for protecting drawing around lines without increasing the number of stages. CONSTITUTION:The front surfaces of projecting part projected form an upper transparent substrate 2 on a lower transparent substrate 1 are provided with an anisotropically conductive layer 16 over the entire part to cover respective external connecting terminals 11, 12, 13 and the drawing-around lines 14, 15. The insulating protective film 24 is formed by the anisotropically conductive layer 16 covering the parts provided with the drawing around lines 14, 15. The insulating protective film 24 for protecting the drawing-around lines 14, 15 is formed without increasing the number of stages by utilizing the insulation characteristic, that the anisotropically conductive layer 16 possesses the insulation characteristic in the plane direction of the transparent substrate 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device.

[0002]

2. Description of the Related Art Generally, a liquid crystal display device is a liquid crystal display panel in which a liquid crystal is sealed between two transparent substrates made of glass or resin, and I for driving the liquid crystal display panel.
A C chip, a circuit board for controlling the IC chip, and the like are provided. Such liquid crystal display devices are roughly classified into three types depending on the arrangement position of the IC chip. First, there is one in which an IC chip is mounted on a circuit board and the liquid crystal display panel and the circuit board are connected via a flexible wiring board. Second, the IC chip is TAB
Mounted on tape, TAB the liquid crystal display panel and circuit board
Some are connected via tape. Thirdly, there is one in which an IC chip is mounted on a liquid crystal display panel and the liquid crystal display panel and a circuit board are connected via a flexible wiring board.

By the way, in a conventional liquid crystal display panel of such a liquid crystal display device, generally, two transparent substrates, each having a transparent electrode provided in a display area of a surface facing each other, are pasted together via a sealing material, A liquid crystal is sealed between two transparent substrates inside the sealing material, and a surface of one of the two transparent substrates, which is a protruding portion protruding from the other transparent substrate, faces the other transparent substrate. The external connection terminal and the routing wire for connecting the external connection terminal to the transparent electrode or the like of one transparent substrate are provided in the structure. Then, the connection terminal of the flexible wiring board, the connection terminal of the TAB tape, or the connection electrode of the IC chip is connected to the external connection terminal of one transparent substrate. When the IC chip is mounted on one transparent substrate, an external connection terminal and a lead wire for connecting the external connection terminal to the IC chip external connection terminal are further provided on the one transparent substrate, and the external connection terminal is flexible. The connection terminals of the wiring board are connected.

[0004]

However, in such a conventional liquid crystal display device, since the routing line of one transparent substrate is exposed, when foreign matter such as conductive dust adheres, the spacing between the adjacent routing lines is reduced. May cause a short circuit, and if moisture or the like adheres to it, the lead wire made of the same material as the transparent electrode (ITO) may be electrolytically corroded and broken (for example, if moisture is not If a potential difference occurs between these two routing wires with electrolyte dust attached, electrolytic corrosion will occur.) Furthermore, if foreign matter such as dust hits, the routing wires may be damaged and broken. there were. In particular, when an IC chip is mounted on one transparent substrate, due to the flow of technology such as increasing the density and increasing the number of pins (connection electrodes) of the IC chip,
Since the number of routing lines increases and the total length of the routing lines increases, and the pitch of the routing lines near the IC chip mounting portion tends to become fine, the above-mentioned problems are remarkable. In order to solve such a problem, for example, an IC chip is mounted on one transparent substrate and a flexible wiring substrate is connected to the one transparent substrate, and then a wiring line of the one transparent substrate is exposed. In some cases, an insulating protective film made of resin is provided by using a dispenser or the like, but in this case, the step of providing the insulating protective film made of resin is required, and the number of steps is increased accordingly. There was another problem. An object of the present invention is to provide a liquid crystal display device capable of forming an insulating protective film for protecting a routing line without increasing the number of steps.

[0005]

According to the present invention, a surface of a projecting portion of one transparent substrate of two laminated transparent substrates, which is projected from the other transparent substrate, faces the other transparent substrate. In a liquid crystal display device provided with an external connection terminal and a routing wire for the external connection terminal, a surface of a protruding portion of the one transparent substrate, which protrudes from the other transparent substrate, faces the other transparent substrate. At least the portion where the external connection terminal and the routing wire are provided is covered with an anisotropic conductive adhesive layer,
An insulating protective film is formed by the anisotropic conductive adhesive layer that covers the portion where the routing line is provided.

[0006]

According to the present invention, the anisotropic conductive adhesive layer used for connecting the IC chip or the flexible wiring board to the external connection terminal is also provided in the portion where the routing wire is provided, and the anisotropic conductive adhesive layer is provided. By utilizing the fact that the adhesive layer has an insulating property in the surface direction of the transparent substrate, it is possible to form an insulating protective film for protecting the wiring lines without increasing the number of steps.

[0007]

1 shows a main part of a liquid crystal display device according to an embodiment of the present invention, and FIG. 2 shows a cross section taken along line XX of FIG. This liquid crystal display device includes a lower transparent substrate 1 made of glass or resin and an upper transparent substrate 2 also made of glass or resin. Transparent electrodes 3 and 4 and alignment films 5 and 6 are provided in the display areas of the surfaces of the transparent substrates 1 and 2 which face each other.
The transparent substrates 1 and 2 are attached to each other with the seal material 7 interposed therebetween, and the liquid crystal 8 is sealed inside the seal material 7 between the alignment films 5 and 6 of the transparent substrates 1 and 2.

In this liquid crystal display device, the lower transparent substrate 1
Has one end protruding from one side surface of the upper transparent substrate 2. At the center of the upper surface of the projecting portion of the lower transparent substrate 1, an IC chip output side external connection terminal 11 is provided on the right side and an IC chip input side external connection terminal 12 is provided on the left side in FIG. In addition, a flexible wiring board external connection terminal 13 is provided at the center of the upper surface of the tip of the protruding portion of the lower transparent substrate 1. further,
The IC chip output side external connection terminal 11 and the transparent electrode 3 are provided at predetermined positions on the upper surface of the protruding portion of the lower transparent substrate 1.
A routing wire 14 for connecting the IC chip and the routing wire 15 for connecting the IC-side input side external connection terminal 12 and the flexible wiring board external connection terminal 13 are provided.

An anisotropic conductive adhesive layer 16 is provided on the entire upper surface of the protruding portion of the lower transparent substrate 1 so as to cover the external connection terminals 11, 12, 13 and the routing lines 14, 15. The anisotropic conductive adhesive layer 16 does not necessarily have to be provided on the entire upper surface of the protruding portion, but is provided so as to cover at least the portion where the external connection terminals 11, 12, 13 and the routing wires 14, 15 are provided. It ’s good. The anisotropic conductive adhesive layer 16 is a conductive particle 18 such as a metal particle in an insulating adhesive 17 made of a thermosetting epoxy resin or a thermoplastic resin, or a particle formed by coating the surface of a resin filler with a metal. Are dispersed and have an insulating property in the initial plane direction and the thickness direction. And
The IC chip 19 is connected to the external connection terminals 11 and 12 via the anisotropic conductive adhesive layer 16. That is,
On the upper surface of the anisotropic conductive adhesive layer 16, the IC chip 19 is provided with the respective connection electrodes 20 and 21 of the predetermined external connection terminals 11,
The connection electrodes 20 and 21 are aligned and placed so as to be connected to the device 12, and are pressed while being heated to crimp the connection electrodes 20 and 21 to the predetermined external connection terminals 11 and 12. Then, the insulating adhesive 17 in the anisotropic conductive adhesive layer 16 is softened by this heat, and a part of the softened insulating adhesive 17 escapes, so that the conductive in the anisotropic conductive adhesive layer 16 is reduced. A part of the conductive particles 18 are brought into contact with the external connection terminals 11 and 12 and the connection electrodes 20 and 21, respectively, whereby the external connection terminals 11 and 12 and the IC
The connection electrodes 20 and 21 of the chip 19 are electrically connected via the conductive particles 18. Further, the once softened insulating adhesive 17 is hardened, so that the connection portion including the external connection terminals 11 and 12 and the connection portion including the connection electrodes 20 and 21 are bonded. Similarly, the anisotropic conductive adhesive layer 1 is also applied to the flexible wiring board external connection terminal 13.
The connection terminal 23 of the flexible wiring board 22 is connected via 6.

An insulating protective film 24 is formed on the portion where the routing lines 14 and 15 are provided by an anisotropic conductive adhesive layer 16 that covers the portion. That is, the anisotropic conductive adhesive layer 16 is heat-treated so that the insulating adhesive 17 therein is once softened and then cured in that state to form the insulating protective film 24. At this time, the anisotropic conductive adhesive layer 16 cures while maintaining insulation in the surface direction and the thickness direction of the lower transparent substrate 1.
Therefore, the insulating protective film 24 is formed on each of the routing lines 14, 1
5 to prevent water and dust from adhering and to have excellent insulating properties in the surface direction and the thickness direction of the lower transparent substrate 1 and to prevent a short circuit between the respective routing lines 14 and 15. Therefore, the routing line 14 , 15 is not likely to be broken. It should be noted that one end of the upper transparent substrate 2 is projected from one side surface of the lower transparent substrate 1, and the anisotropic conductive adhesive layer 26 is provided on the entire upper surface of this protruding portion in the same manner as above. IC
The chip 25 and the branched flexible wiring board 22a are connected, and an insulating protective film is formed on the portion where the routing wire (not shown) is provided in the same manner as above.

In the liquid crystal display device thus obtained, the anisotropic conductive adhesive layer 16 used for connecting the IC chip 19 and the flexible wiring substrate 22 to the external connection terminals 11, 12, 13 is a lead wire. The number of steps is increased by using the fact that the anisotropic conductive adhesive layer 16 has an insulating property in the surface direction of the lower transparent substrate 1 by providing it also in a portion where 14 and 15 are provided. Without doing so, the insulating protective film 24 for protecting the routing lines 14 and 15 can be formed.

FIG. 3 shows a cross section of a liquid crystal display device according to another embodiment of the present invention. In this figure,
The same parts as those in FIG. 2 are designated by the same reference numerals, and the description thereof will be omitted as appropriate. In this embodiment, a part of the anisotropic conductive adhesive layer 16 corresponding to the lower surface of the IC chip 19 is excluded. Therefore, the IC chip 19
The cavity 27 is formed in the portion corresponding to the lower surface of the. When the cavity 27 is formed in this way, the stress due to the expansion and contraction of the anisotropic conductive adhesive layer 16 can be relaxed, and the adhesive strength becomes weaker than that in the case of FIG. Even if a defect is found by conducting an electrical operation test after mounting the chip 19, the defective IC chip 19 can be easily removed, and the IC chip 19 can be easily replaced.

[0013]

As described above, according to the present invention, the portion where the routing wire is provided for the anisotropic conductive adhesive layer used when connecting the IC chip or the flexible wiring board to the external connection terminal. In addition, the anisotropic conductive adhesive layer has insulating properties in the surface direction of the transparent substrate, so that it is possible to protect the lead wires without increasing the number of steps. A film can be formed.

[Brief description of drawings]

FIG. 1 is a plan view of a main part of a liquid crystal display device according to an embodiment of the present invention.

FIG. 2 is a sectional view taken along line XX in FIG.

FIG. 3 is a sectional view of a main part of a liquid crystal display device according to another embodiment of the present invention.

[Explanation of symbols]

 1, 2 Transparent substrate 3, 4 Transparent electrode 7 Sealing material 8 Liquid crystal 11, 12, 13 External connection terminal 14, 15 Lead wire 16 Anisotropic conductive adhesive layer 19 IC chip 22 Flexible wiring board 24 Insulating protective film

Claims (1)

[Claims] 1. An external connection terminal and the external connection are provided on a surface of a protruding portion of one transparent substrate of the two bonded transparent substrates which is protruded from the other transparent substrate, the surface facing the other transparent substrate. In a liquid crystal display device provided with a lead wire for a terminal, at least the external connection terminal of at least a surface of a protruding portion of the one transparent substrate that protrudes from the other transparent substrate, the surface facing the other transparent substrate. A portion where the routing wire is provided is covered with an anisotropic conductive adhesive layer, and an insulating protective film is formed by the anisotropic conductive adhesive layer that covers the portion where the routing wire is provided. Characteristic liquid crystal display device.