JPH0667194A - Liquid crystal display device - Google Patents

Abstract

(57) [Summary] [Object] The present invention relates to a liquid crystal display device, which has flexibility in array design, drive LSI, and mounting method, and also provides wire breakage relief, high yield, low cost, and display quality. An object is to provide an excellent liquid crystal display device. [Structure] In a liquid crystal display device, at least two or more electrodes are provided for an auxiliary signal line 6 for repairing disconnection, and a metal wiring 28 is provided between electrodes of the same signal.

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 capable of high performance and high yield.

[0002]

2. Description of the Related Art In recent years, liquid crystal display devices have been actively approached for large-capacity display typified by image display, and have attracted the most attention as displays capable of realizing low-priced devices.

FIG. 8, FIG. 9 and FIG. 10 are examples of conventional liquid crystal display devices, and are diagrams showing the structure of a matrix type liquid crystal display device.

First, the liquid crystal panel will be described with reference to FIG. FIG. 8 is a sectional view showing the structure of a conventional liquid crystal display device. The image display region 9 including the switching element group 12, the pixel electrode 11, the alignment film 15, the source signal wiring 13, and the gate signal wiring 14, and the signal electrode 5 from the external drive circuit.
An array substrate 21 made of a transparent insulator having a transparent substrate, a counter substrate 22 made of a transparent insulator having a transparent common electrode 19, a light shielding layer 18 and an alignment film 15 provided with a spacer 16 made of glass fiber or resin fine particles. , Pixel electrode 1
1 and the transparent common electrode 19 are opposed to each other and bonded with a sealing material 20, and the gap formed by the spacer 16 is filled with the liquid crystal composition 17.

The liquid crystal panel 1 configured as described above is
Arbitrary information can be displayed by selectively applying a voltage to the pixel electrodes 11 via the switching element 12.

FIG. 9 shows a plan view of a liquid crystal panel.
In the switching element 12 forming the image display area 9, the source signal wiring 13 and the gate signal wiring 14 are orthogonal to each other. Therefore, the signal input electrode from the external driving circuit is divided into a source side signal input electrode and a gate side signal input electrode.

FIG. 10 is an enlarged plan view of one of the signal electrode 6 and the auxiliary electrode 6 in FIG. The signal electrode 5 is connected to a switching element (not shown) for driving liquid crystal in the display region 9 via the signal wiring pad 7, and the auxiliary electrode 6 provided adjacent to the signal electrode 5 is Display area 9
It is connected to an auxiliary wiring pad 8 provided outside.

Next, a conventional method of manufacturing a liquid crystal display device will be described. FIG. 11 is a manufacturing flowchart of a conventional liquid crystal display device. After the array substrate is completed by the array process, the signal wiring in the image display region is inspected for disconnection by an electrical method. Here, a good product and a defective product are sorted, and a defective product, that is, a product having a disconnection is repaired by wire bonding or the like.

That is, in FIG. 10, one of the signal wiring pads 7 of the signal electrode 5 having the disconnection and the auxiliary electrode pad 8 of the auxiliary electrode 6 are electrically connected by using the wire wiring 25 made of a material such as aluminum. Further, the auxiliary electrode is wired to an opposing one of the auxiliary electrodes through an external circuit board (not shown) and the like. Further, the wiring is connected to the broken signal line.

As described above, by performing the wire wiring at both ends of the signal wiring in which the disconnection occurs, the disconnection can be remedied even in the liquid crystal display device in which the signal is input from only one side.

The liquid crystal panel repaired for the disconnection is checked again by inspection, and then the drive LSI is mounted.

The drive LSI is mounted on a TAB (Tape A
12 is the mainstream of the automated bonding method, and FIG. 12 shows a TCP (Tap) in which a driving LSI is mounted on a TAB.
The top view and sectional drawing of eCarrier Package) are shown. The drive LSI 3 is bonded on a base material 23 such as polyimide, and a metal pattern (collectively 24) for the output signal wiring 24a, the input signal wiring 24b, and the auxiliary signal wiring 24c of the drive LSI 3 is bonded on the base material 23. Has been formed.

FIG. 13 shows a plan view of a state of mounting on a liquid crystal panel using TCP. For joining the liquid crystal panel 1 and the TCP 2, for example, an anisotropic conductive adhesive (not shown) is used,
The TCP 2 and the printed circuit board 4 are mounted by soldering or the like. The TCP 2 and the printed circuit board 4 are mounted, and wiring for peripheral circuits (not shown) is made to complete the liquid crystal display device.

[0014]

According to the device structure in the conventional manufacturing method, the signal for repairing the disconnection needs to be connected in at least three places, and the total resistance is at least three times that in the normal case. Resistance.

FIG. 14 shows an equivalent circuit of the wiring for repairing the disconnection, and the wiring path will be described by using the reference numerals of FIGS. 14, 13 and 12. The output signal from the drive LSI 3 is TCP
The second output signal wiring 24a and the signal electrode 5 of the liquid crystal panel are connected to the auxiliary wiring pad 8 by the wire bonding, and then the auxiliary electrode 6 to TCP2.
Connection resistance Rc to the auxiliary electrode 6b via the TCP2 wiring opposite thereto via the connection resistance Rb to the auxiliary signal wiring 24c.
Connected by.

The metal pad of the auxiliary electrode 6b is connected to the signal wiring pad 7b on one side of the broken display signal line by the wire wiring 25. In other words, the cumulative connection resistance from the drive LSI for the signal line that has been repaired for disconnection is Ra + Rb +
It becomes Rc, and in the case of a normal signal line, only Ra is required, but two more connection parts are required.

Normally, ITO (indium-tin oxide), which is physically stable, is used as the material of the connecting electrode, but ITO has a relatively high sheet resistance. In particular, as the circuit pitch becomes narrower as the pixel pitch becomes narrower due to higher precision in recent years, the resistance per line of the connection electrode tends to increase.

On the other hand, the driving LSI of the liquid crystal display device has a limited output current capacity due to low power consumption and high density. That is, the connection resistance also needs to be restricted.

Particularly for a high-quality liquid crystal display device, a minute output deviation is also recognized as display deterioration.

However, as described above, the signal for which the disconnection has been repaired has a higher resistance as a whole because it requires more connection parts than usual. As a result, the display of the rescued signal line shows a slight variation with respect to the display of other signal lines. That is,
A line defect was generated on the display screen, resulting in deterioration of display quality.

Normally, in the mounting method using TAB, the wiring electrodes of the liquid crystal panel are made of ITO, and in order to reduce the wiring resistance, metal wiring made of, for example, aluminum indium or chrome is provided as a backup resistance on the side surface of the ITO. Is given as.

As an example, FIG. 15 shows a cross-sectional view of an electrode when aluminum backup wiring is provided.
When metal wiring is formed by the aluminum film 28, the aluminum film 28 is replaced with the ITO film 2 as shown in FIG.
7, the metal wiring is covered with the insulating film 29, which is further convex, and the width of the metal wiring is required. The thickness of the metal film and the thickness of the insulating film must be 1 to 2 μm or more. Further, due to the higher precision of the liquid crystal display device, it is necessary to narrow the pitch of the mounting, and the mounting accuracy becomes an important factor in the mounting of the 150 μm pitch or the 120 μm pitch.

As described above, when the backup electrode is provided, the backup wiring becomes convex, the metal pattern of the TCP rides on the convex portion, and sufficient connection with ITO cannot be obtained, resulting in poor connection reliability. . FIG. 15 shows a conceptual cross-sectional view of the mounted state when riding on the convex portion. TCP
The metal pattern 24 of FIG. 2 rides on the convex portion formed by the metal wiring of the liquid crystal panel 1, and the connection with the ITO film 27 cannot be sufficiently obtained.

Specifically, for example, when a TCP mounting with a pitch of 150 μm and a number of about 200 terminals is used and the width of the TCP is 30 mm, the pattern accuracy is ± 40 μm at maximum.
Hereinafter, assuming that the minimum width of the metal pattern is 60 μm and the alignment accuracy required for production is ± 30 μm, the electrode width of the liquid crystal panel is the metal pattern width 60 + pattern accuracy 4
0 + alignment accuracy 30 = 130 μm is required.

Considering the insulating properties of adjacent electrodes,
The maximum is 130 μm. If metal backup wiring is applied to the electrodes, the width required for the wiring is 20 to 30 μm.
m, and wiring is difficult at a pitch of 150 μm. If the wiring is provided, the metal pattern 24 of the TCP rides on the convex portion as described above, which causes poor reliability.

Therefore, an object of the present invention is to provide a liquid crystal display device which eliminates the above-mentioned drawbacks while repairing disconnection and which is excellent in display quality by a simple method.

[0027]

In order to solve the above-mentioned problems, the present invention provides at least two auxiliary wiring electrodes, or provides a metal wiring in a gap between a plurality of electrodes of the same signal or electrodes. The connection resistance of the auxiliary wiring electrode portion is reduced by means such as widening the width.

[0028]

In the liquid crystal display device configured as described above, it is possible to change the design to have excellent display quality while repairing the disconnection as in the conventional case. As a result, the yield and display performance of the liquid crystal display device can be dramatically improved. When driving a liquid crystal panel, not only for repairing broken wires,
It is also effective especially for signals that require low impedance.

[0029]

EXAMPLES Examples of the present invention will be described below. Figure 1
FIG. 1 is a configuration plan view of a liquid crystal display device according to an embodiment of the present invention. The liquid crystal display device mainly includes a liquid crystal panel 1, a TCP 2 on which a drive LSI is mounted, and a printed circuit board 4 on which peripheral circuits are mounted.

The liquid crystal panel will be described with reference to FIG. The structure of the liquid crystal panel 1 is such that a thin film transistor (T
A switching element 12 made of FT) and a pixel electrode 11 made of ITO are formed. As a driving signal line of the switching element 12, a source signal wiring 13 made of a metal such as aluminum or the like, and a gate signal wiring which is perpendicular to the source signal wiring 13 are formed. 14 is also made of metal.

A detailed description of the electrode structure of this embodiment will be given with reference to FIG. The signal electrode of the liquid crystal panel 1 is an external drive LS.
Wiring is provided outside the display area 9 for mounting I. The signal electrode 5 is connected to the signal wiring pad 7 outside the display area 9, and further connected to a switching element (not shown in FIG. 3) in the display area 9. Two auxiliary electrodes 6 are formed adjacent to the signal electrode 5. The two auxiliary electrodes 6 are connected at the center with a metal 28 such as aluminum. Here, the two auxiliary electrodes are connected to one auxiliary wiring pad 8 outside the display area 9.

The configurations, purposes, and operations of the alignment film 15, the spacer 16, and the liquid crystal composition 17 shown in FIG.

FIG. 4 is a plan view of a TCP on which a drive LSI is mounted. The mounting of the base material 23 and the drive LSI 3 and the configuration of the metal pattern 24 and the like for signal output and signal input are the same as the conventional ones. In this embodiment, the auxiliary signal wiring 24c is TC
Two wires are provided at both ends of P2, and two auxiliary wires are TC.
It is connected inside P2. Here, the auxiliary wiring may be connected inside the printed circuit board or inside the peripheral circuit.

The printed circuit board 4 has a drive LS as in the conventional case.
An I input signal electrode and an auxiliary signal electrode are formed (not shown).

FIG. 5 shows an equivalent circuit of the wiring for repairing the disconnection in this embodiment, and the wiring route will be described mainly using the reference numerals of FIG. The output signal from the drive LSI 3 is TCP2
Of the output signal wiring 24a and the signal electrode 5 of the liquid crystal panel, and is connected to the auxiliary wiring pad 8 by the wire wiring 25, and then from the two auxiliary electrodes 6 to the two T electrodes.
The connection resistance (RcS) is connected to the auxiliary electrode 6b via the connection resistance (RbS) of the CP2 to the auxiliary signal wiring 24c and the opposing TCP2 wiring. The metal pad of the auxiliary electrode 6b is connected to one signal wiring pad 7b of the broken display signal line by the wire wiring 25.
That is, the cumulative connection resistance from the drive LSI of the signal line that has been repaired for disconnection is Ra + (RbS) + (RcS) = Ra, (R
bS and RcS are infinitely small with respect to Ra), and the cumulative resistance is reduced. In this embodiment,
Although two auxiliary wirings were connected in parallel, there is no restriction on the number of parallel wirings.

FIG. 6 is an explanatory view of another embodiment of the present invention. The same applies to the configuration of the image display area and the method for relieving the disconnection. Here, the width of the auxiliary wiring electrode electrode is widened, and two leads are mounted in one electrode. In this configuration, since the ITO area is increased, the resistance itself is reduced, and the amount depending on the change of one connection resistance is reduced.

FIG. 7 is an explanatory view of still another embodiment of the present invention. The auxiliary electrode, which is made of two ITO, is used as the display area 9
Wired to one outside. By wiring two electrodes in parallel, it is possible to reduce the connection resistance without providing metal wiring.

[0038]

As described above, according to the present invention, the auxiliary wiring of the liquid crystal panel is formed into at least two or more column wirings, the metal wiring is provided between the electrodes, or the electrode width is widened. In the same construction method, the wiring resistance of the signal for repairing the disconnection is reduced to eliminate the display deterioration of the repaired signal,
It is possible to repair the disconnection without degrading the display quality of the liquid crystal display device.

[Brief description of drawings]

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

FIG. 2 is a sectional view of the apparatus of the same embodiment.

FIG. 3 is a plan view showing details of the apparatus of the embodiment.

FIG. 4 is a plan view of TCP in the apparatus of the embodiment.

FIG. 5 is an equivalent circuit diagram of the device of the same embodiment.

FIG. 6 is a plan view showing details of an apparatus according to another embodiment of the present invention.

FIG. 7 is a plan view showing details of an apparatus according to still another embodiment of the present invention.

FIG. 8 is a sectional view of a conventional liquid crystal display device.

FIG. 9 is a plan view of an array substrate of the conventional liquid crystal display device.

FIG. 10 is an enlarged view of electrodes of the conventional device.

FIG. 11 is a manufacturing process diagram of the conventional device.

12A is a plan view of a TCP of the conventional device, and FIG. 12B is a sectional view thereof.

FIG. 13 is a plan view of a conventional liquid crystal display device.

FIG. 14 is an equivalent circuit diagram for repairing disconnection in a conventional liquid crystal display device.

FIG. 15 is a sectional view of a conventional mounting terminal provided with backup wiring.

FIG. 16 is a conceptual diagram in the case of riding on a convex portion of a conventional backup wiring.

[Explanation of symbols]

 1 Liquid Crystal Panel 2 TCP 3 Drive LSI 4 Printed Circuit Board 5 Signal Electrode 5a Signal Electrode 6 Auxiliary Electrode 6a Auxiliary Electrode 7 Signal Wiring Pad 7a Signal Wiring Pad 8 Auxiliary Wiring Pad 8a Auxiliary Wiring Pad 9 Display Area 10 Glass Substrate 11 Pixel Electrode 12 Switching Element 13 Source signal wiring 14 Gate signal wiring 15 Alignment film 16 Spacer 17 Liquid crystal composition 18 Light shielding layer 19 Transparent common electrode 20 Sealing material 21 Array substrate 22 Counter substrate 23 TCP base material 24 TCP metal pattern 24a TCP output signal wiring 24b TCP input Signal wiring 24c TCP auxiliary signal wiring 25 Wire wiring 26 Disconnection 27 ITO film 28 Aluminum film 29 Insulating film

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Koichi Okamoto 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.

Claims (2)

[Claims] 1. A liquid crystal display in which a pair of substrates with electrodes, at least one of which is transparent, are arranged such that their electrode surface sides face each other and a predetermined gap is maintained, and the gap is filled with a liquid crystal composition. In the mounting terminal that is a device and electrically connects the display electrode and the external drive circuit,
A liquid crystal display device characterized by wiring a plurality of electrodes for one specific signal. 2. The liquid crystal display device according to claim 1, wherein the connection electrode with the external drive circuit is made of ITO, and the specific electrode area is widened.