JP3258100B2 - LCD panel - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrode provided on a substrate constituting a liquid crystal panel, for example, a structure of a transparent electrode, and more particularly to improvement of connectivity between the transparent electrode and other members.

[0002]

2. Description of the Related Art A liquid crystal display panel is basically constructed by sealing two transparent substrates on which a transparent electrode, which is an electrode, is formed with a sealing material and injecting a liquid crystal material into the transparent substrate. A pixel electrode is formed inside the sealing material, and is drawn out of the sealing material to form a wiring electrode.

The wiring electrode of this transparent electrode is directly connected to the FPC.
(Flexible printed circuit), or connected to an external circuit via anisotropic conductive rubber, or a semiconductor integrated circuit device (hereinafter referred to as a drive IC) for driving a liquid crystal display panel. is there.

The following description will be made with respect to a liquid crystal display panel in which a drive IC is face-down bonded to a substrate constituting the liquid crystal display panel. It is related to the improvement of connectivity with, and is not limited to the mode of description.

FIG. 3 is a schematic plan view showing a liquid crystal display panel obtained by face-down bonding a drive IC to a substrate constituting the liquid crystal display panel. As shown in FIG. 3, the first substrate 101 and the second substrate 102 are
And liquid crystal is filled in the sealed area. The driving IC 1 is connected to the wiring electrode 103 drawn out on the first substrate 101.
06. FPC 11 is further provided on the wiring electrode 103.
3 and supplies signals and the like from the outside.

FIG. 4 is a schematic cross-sectional view showing a conventional structure example, and shows a cross section taken along line AA in FIG. In FIG. 4, structural details such as an alignment film are omitted. Hereinafter, a conventional liquid crystal display panel will be described with reference to FIG.

In the conventional liquid crystal display panel shown in FIG. 4, a pixel electrode 104 and a wiring electrode 103 corresponding to an electrode of a driving IC 106 are formed on a first substrate 101 in the following steps.

First, an indium tin oxide (hereinafter referred to as ITO) film as a transparent electrode film is formed on the entire surface of the first substrate 101 by using a sputtering method, a vacuum evaporation method, a pyrosol method, or the like.

Thereafter, a photoresist is applied to the entire surface on which the ITO film is formed, and is exposed, developed, and etched through a photomask having a desired pattern shape. To form

A pixel electrode 105 and a wiring electrode (not shown) are formed on the second substrate 102 by the same process, and the first substrate 101 and the second substrate 102 are separated from each other by a predetermined distance. Seal with a sealant 110.

Further, the first substrate 101 and the second substrate 10
A liquid crystal (not shown) is sealed in a region overlapping the area 2 and inside the sealing material 110.

The wiring electrode 103 formed on the first substrate 101 and the protruding electrode 107 which is a connection electrode formed in advance on the electrode portion of the driving IC 106 are face-down by a conductive adhesive 108. Bonding is performed to make electrical and mechanical connections.

First substrate 1 further including drive IC 106
01 is resin-sealed with resin 109 and solder plating 1
The FPC 113 subjected to the step 14 is connected to the wiring electrode 103 by a thermocompression bonding method.

[0014]

SUMMARY OF THE INVENTION It is considered that the above-mentioned structure is simple, can connect many terminals at high density, and can provide a small and inexpensive liquid crystal display panel.

When the current vacuum deposition method is employed as a method for forming ITO, there are the following disadvantages. That is, the ITO film formed by the vacuum deposition method is relatively rough, and pinholes are easily generated.

If a pinhole occurs on the pixel electrodes 104 and 105, a pixel defect is caused, and
When a pinhole is generated on the upper side, crosstalk increases due to an increase in wiring resistance, resulting in deterioration of image quality, and furthermore, disconnection of the wiring electrode 103, which significantly lowers the yield.

The wiring electrode 103, the pixel electrodes 104 and 105
It has been considered to increase the thickness of the ITO film in order to prevent the occurrence of the upper pinhole. However, since the light transmittance of the ITO film is reduced or the step portion of the ITO film is increased,
The liquid crystal orientation becomes non-uniform, causing new problems such as lowering the display quality, and is not a practical solution.

On the other hand, an ITO film formed by a sputtering method or a pyrosol method is relatively dense and has very few pinholes.

Therefore, the wiring electrode 103 and the pixel electrode 10
If the films 4 and 105 are formed of an ITO film formed by a sputtering method or a pyrosol method, it is possible to suppress a decrease in yield due to pixel defects, disconnection, and the like.

However, when an ITO film actually formed by a sputtering method or a pyrosol method is used as a transparent electrode layer, the wiring electrode 103 via the conductive adhesive 108 is used.
Connecting portion with the protruding electrode 107 or solder plating 11
In some cases, electrical and mechanical connections are unstable at the connection between the wiring electrode 103 and the FPC 113 via the wiring 4.

In such a case, the conventional wiring electrode 103
Gold plating is used. In fact, according to this conventional method, connection instability is eliminated. However, this conventional technique greatly increases the number of steps and the cost.

The present invention has been made to solve such a problem, and an object of the present invention is to obtain a transparent electrode having a small number of pinholes, and at the same time, to improve the connectivity between a wiring electrode and another member, and An object of the present invention is to provide a liquid crystal display panel having stable display and mechanical connections and high display quality.

[0023]

Means for Solving the Problems The present invention to solve the conventional problems, the two transparent substrates a transparent electrode layer is formed, arranged said transparent electrode layer is provided with a gap as opposed and sealed by a sealing material around the said gap, a liquid crystal panel constructed by a liquid crystal material is injected該間the gap, small
The transparent electrode layer formed on at least one of the substrates
Is to form a pixel electrode inside the sealing material
In both cases, a wiring electrode is formed outside the sealing material.
In a liquid crystal panel in which another member is connected to at least a part of the wiring electrode, at least a part in front of the wiring electrode
Portion connected with serial other member has at least a first transparent conductive <br/> electrode layer, the more becomes the multilayer structure and the second transparent <br/> electrode layer formed on the first transparent electrode layer above without a, and the transparent conductive <br/> electrode layer of the second is characterized by than the first transparent electrode layer was used as a crude layer.

Further, the other member connects the external circuit.
It is a feature of the FPC .

Further, the said second transparent electrode layer of the wiring electrodes FPC, characterized in that it is connected with an adhesive mixed with the conductive particles in the resin.

The other member is a semiconductor integrated circuit .

Further, the semiconductor device is characterized in that the second transparent electrode layer of the wiring electrode and the semiconductor integrated circuit are connected by an adhesive in which conductive particles are mixed in a resin.

Further, the first transparent electrode layer and the second transparent electrode layer
The transparent electrode layer and the transparent electrode layer are both formed of a layer of indium tin oxide.

Further, the first transparent electrode layer is formed by sputtering.
It is characterized by being formed by a ring method .

Further, the second transparent electrode layer may be formed by a vacuum evaporation method or a sputtering method having different conditions from the first transparent electrode layer.
It is characterized by being formed by a ring method .

Further, the conductive adhesive has a constitution in which conductive particles of Ag / Pd are mixed in an epoxy resin agent.

[0032]

[0033]

[0034]

[0035]

[0036]

[0037]

When a wiring electrode is formed by an ITO film formed by a vacuum deposition method, the above-mentioned unstable connection phenomenon occurs.
It is not seen. As described above, when the wiring electrode is formed of the ITO film formed by the vacuum evaporation method, the connection portion between the wiring electrode and the protruding electrode via the conductive adhesive or the wiring electrode via the solder plating is formed. The connection with the FPC is electrically and mechanically stable.

When the cause of the instability of the electrical and mechanical connection in the case where the wiring electrode was formed by the ITO film formed by the sputtering method or the pyrosol method, the following situation was found.

That is, the ITO film formed by the sputtering method or the pyrosol method is relatively dense, and its surface is very smooth. As a result, the adhesiveness with a conductive adhesive, solder, or the like is poor, and the connectivity is reduced. On the other hand, an ITO film formed by a vacuum deposition method is relatively rough, and its surface has poor smoothness. As a result, the adhesiveness with a conductive adhesive, solder, or the like is good, and the connectivity is improved.

Therefore, the wiring electrode is made of an IT having few pinholes.
The above problem can be solved by forming a multilayer structure including a first transparent electrode layer made of an O film and a second transparent electrode layer made of an ITO film having a rough surface and good connectivity with other members.

[0041]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the drawings, but the embodiment will be applied to a liquid crystal display panel in which a driving IC is face-down bonded to a substrate constituting a liquid crystal display panel in accordance with a conventional example.

FIG. 1 is a schematic sectional view of a liquid crystal display panel according to a first embodiment of the present invention, and the corresponding plan view also shares FIG. FIG. 1 shows a cross section taken along line AA of FIG.
Hereinafter, the liquid crystal display panel of the present invention will be described with reference to FIG. 1. However, the figure shows only the structure, not the dimensions.

As shown in FIG. 1, the first surface of the first substrate 101 is first formed of an ITO film using a sputtering method.
Is provided. Next, a portion other than the portion where the wiring electrode 103 is to be formed is masked, and only the portion where the wiring electrode 103 is to be formed is made of a second ITO film using a vacuum deposition method.
Is selectively provided.

Thereafter, a photoresist is applied over the entire surface of the ITO film, and a pixel electrode 104 and a wiring electrode 103 are formed by a so-called photoetching method of exposing, developing, and etching through a photomask having a predetermined pattern shape.

As a result, the pixel electrode 104 has a single-layer structure including only the first transparent electrode layer 111 made of an ITO film provided by a sputtering method. On the other hand, the wiring electrode 1
03 has a two-layer structure of a first transparent electrode layer 111 made of ITO sowed using a sputtering method and a second transparent electrode layer 112 made of an ITO film provided using a vacuum evaporation method. Become.

When the means of the present invention is also applied to the second substrate 102, the pixel electrode 1 is subjected to the same process as the first substrate 101.
05, a wiring electrode (not shown) is formed.

After that, the first substrate 101 and the second substrate 1
02 with a predetermined distance from the pixel electrode 104 and the pixel electrode 1
05 are formed facing each other, and the periphery thereof is sealed with a sealing material 110.
Seal with.

Further, the first substrate 101 and the second substrate 10
A liquid crystal (not shown) is sealed in a region where 2 overlaps and a portion inside the sealing material 110.

Then, the wiring electrodes 103 formed on the first substrate 101 and the protruding electrodes 107 formed in advance on the electrode portions of the driving IC 106 are face-down bonded with a conductive adhesive 108 to provide electrical and mechanical connection. I take the.

First substrate 1 further including drive IC 106
01 is resin-sealed with a resin 109, and an FPC 113 further subjected to solder plating is connected to the wiring electrode 103 by a thermocompression bonding method.

FIG. 2 is a schematic sectional view showing a liquid crystal display panel according to a second embodiment of the present invention, and shows a section taken along line AA in FIG. Hereinafter, a second embodiment of the present invention will be described with reference to FIG.

As shown in FIG. 2, a first transparent electrode layer 111 of an ITO film is formed on the entire surface of the first substrate 101 by using a sputtering method. Next, a second transparent electrode layer 112 of ITO using a vacuum deposition method is provided on the entire surface of the first transparent electrode layer 111 to form a two-layer structure.

Thereafter, a photoresist is applied to the entire surface of the ITO film, and a pixel electrode 104 and a wiring electrode 103 are formed by a so-called photo etching method of exposing, developing, and etching through a photo mask having a predetermined pattern shape.

As a result, the pixel electrode 104 and the wiring electrode 10
3 has a two-layer structure of a first transparent electrode layer 111 made of an ITO film provided by using a sputtering method and a second transparent electrode layer 112 made of an ITO film provided by using a vacuum deposition method. Will be.

When the means of the present invention is also applied to the second substrate 102, the pixel electrode 1 is subjected to the same process as that for the first substrate 101.
05, a wiring electrode (not shown) is formed.

After that, the first substrate 101 and the second substrate 1
02 with a predetermined distance from the pixel electrode 104 and the pixel electrode 1
05 are formed facing each other, and the periphery thereof is sealed with a sealing material 110.
Seal with.

Further, the first substrate 101 and the second substrate 10
A liquid crystal (not shown) is sealed in a region where 2 overlaps and a portion inside the sealing material 110.

Then, the wiring electrodes 103 formed on the first substrate 101 and the protruding electrodes 107 formed in advance on the electrode portions of the driving IC 106 are face-down bonded with a conductive adhesive 108 to make electrical and mechanical connections. take.

First substrate 1 further including drive IC 106
01 is resin-sealed with a resin 109, and an FPC 113 further subjected to solder plating is connected to the wiring electrode 103 by a thermocompression bonding method.

In the second embodiment, the second transparent electrode layer 11
2 is provided on the entire upper surface of the first transparent electrode layer 111. For this reason, as in the first embodiment, the second transparent electrode layer 112
There is no need for a masking means necessary for selectively providing a, and the process is advantageously simplified.

In the above two embodiments, the conductive adhesive 108
An Ag / Pd paste in which a fine powder of Ag / Pd, which is a conductive particle, was mixed in an epoxy resin was used.

The conductive adhesive 108 made of the Ag / Pd paste is spread on the substrate using a squeegee, and then the protruding electrode 107 of the drive IC 106 is brought into contact with the Ag / Pd paste, and the conductive adhesive 108 is applied to the protruding electrode 107. Transcribe.

In this stamp method, a uniform amount of a conductive adhesive 108 is applied to a protruding electrode 107 formed on a driving IC 106.
Can be transcribed.

The protruding electrode 10 to which the conductive adhesive 108 has been transferred
7 is face-down bonded to a predetermined position of the wiring electrode 103 formed on the first substrate 101, and lightly pressed from the side of the driving IC 106 opposite to the protruding electrode 107.

After the conductive adhesive 108 is thermally cured,
The surface of the substrate including the drive IC 106 is sealed with a resin 109.

When the liquid crystal display panel having the structure shown in this embodiment was manufactured, the driving IC 106 or the FPC 11
Thus, a liquid crystal display panel having stable electrical and mechanical connection with No. 3 and having no pixel defects due to pinholes and no disconnection of wiring electrodes was stably obtained.

This means that the surface of the wiring electrode 103 of the present invention has a relatively rough surface formed by vacuum evaporation.
The validity of the configuration using a TO film and using an ITO film formed by a sputtering method with few pinholes in other portions is shown.

In the above embodiment, the first transparent electrode layer 1
Although the case where both the 11th and the second transparent electrode layers 112 are made of ITO films has been shown, they may be formed of a transparent conductive layer such as tin oxide having a composition different from that of the ITO films.

However, it is desirable that the first transparent conductive layer 111 and the second transparent electrode layer 112 have the same or similar composition from the viewpoint of the process. Further, an ITO film is very commonly used as a transparent electrode. Therefore, new equipment is not required, and it is preferable that both the first transparent electrode layer 111 and the second transparent electrode layer 112 be ITO films.

In the above embodiment, the first transparent electrode layer 11
In this example, No. 1 was formed by the sputtering method, and the second transparent electrode layer 112 was formed by the vacuum evaporation method.

However, the gist of the present invention is that the combination of the first transparent electrode layer 111 having a small number of pinholes and the second transparent electrode layer 112 having a moderately large surface roughness provides different characteristics required for the transparent electrode. Therefore, any method of forming each transparent electrode layer may be used as long as this object is achieved.

For example, the first transparent electrode layer 111 is formed by a sputtering method under a condition for forming a dense layer, and the second transparent electrode layer 112 is formed by a sputtering method under a condition for forming a rough layer. Is also good.

In this case, it is possible to continuously form the first transparent electrode layer 111 and the second transparent electrode layer 112 by changing the forming conditions in the middle. As the formation conditions, a substrate temperature, an oxygen partial pressure, a film formation speed, and the like are controlled.

However, in order to easily obtain a transparent electrode layer having a rough surface as the second transparent electrode layer 112, it is most simple to use a vacuum evaporation method.

In the case where at least the first transparent electrode layer 111 is formed of an ITO film, it is desirable to use a sputtering method.

For example, ITO formed by a pyrosol method
Although the film has few pinholes, the specific resistance is relatively high, and the electric resistance value of the wiring electrode 103 and the pixel electrodes 104 and 105 cannot be sufficiently reduced. As is well known, these rises in electric resistance cause so-called crosstalk,
The display quality of the liquid crystal display panel may be reduced.

Of course, if the thickness of the transparent electrode layer is increased, the electric resistance value is reduced, but the light transmittance is lowered and the display quality is lowered due to the non-uniform alignment of the liquid crystal at the step portion of the ITO film.

The IT formed by this point sputtering method
Since the O film can reduce the specific resistance, the wiring electrode 103,
The electric resistance of the pixel electrodes 104 and 105 can be reduced, which is convenient.

As is clear from the description of the above embodiment, the embodiment of the present invention may be limited to the first substrate 101 only. There may be a case where the connection condition between the wiring electrode and another member is different from that of the first substrate 101.

As described above, the present invention is effective when a method using a conductive adhesive and a method using thermocompression bonding with solder are used in connecting the wiring electrode 103 and other members. For example, the present invention is also effective in other connection methods such as a method in which anisotropic conductive rubber is pressed.

Although the present invention is focused on the stability of electrical and mechanical connections, in the second embodiment, the second transparent electrode layer 112 is replaced with the first transparent electrode layer 111.
Since it is provided on the entire upper surface, the adhesion between the sealing material 110 or the alignment film (not shown) and the second transparent electrode layer 112 is also improved. Therefore, in order to obtain such an effect, it is obvious that it may be used only for the purpose of enhancing mechanical connectivity.

Note that another layer may be provided between the first transparent electrode layer 111 and the second transparent electrode layer 112 for the purpose of increasing the adhesion between these two layers, or the first transparent electrode layer 111 may be provided with a first transparent electrode layer. In the case where the electrode layer 111 and the second transparent electrode layer 112 are continuously formed, for example, even when the formation conditions are gradually changed and the boundary between the two layers is not clear, it is partially observed. In the case where there is a part with different characteristics that meets the gist of the present invention, it is included in the present invention.

Here, when the contents of the present invention are arranged, the first means is that at least a part of the transparent electrode is formed by a relatively dense first electrode.
And a multilayer structure having a second transparent electrode layer having a relatively rough surface formed above the first transparent electrode layer. " A transparent wiring electrode having good connectivity with the above member can be obtained.

Further, the second means is that both the wiring electrode and the pixel electrode have a multilayer structure having a first transparent electrode layer and a second transparent electrode layer formed above the first transparent electrode layer.
This makes it possible to simplify the process of implementing the first means.

The third means is that, together with the first or second means, "the first transparent electrode layer and the second transparent electrode layer are both transparent electrode layers formed of indium tin oxide."
This means that conventional processes and equipment can be effectively used.

A fourth means is that the first transparent electrode layer is formed as a transparent electrode layer formed by a sputtering method together with the first, second or third means. The first transparent electrode layer having low resistance can be easily obtained.

The fifth means is to make the second transparent electrode layer a transparent electrode layer formed by a vacuum evaporation method together with the first, second, third or fourth means. A second transparent electrode layer having a rough surface can be easily obtained.

The sixth means is that, together with the first, second, third, fourth, or fifth means, the driving IC is provided on the wiring electrode.
Face-down bonding with a conductive adhesive via a protruding electrode ".
The effect of the means can be enhanced.

[0089]

As is clear from the above description, according to the present invention, at least the wiring electrodes are provided in the liquid crystal display panel.
By forming a multilayer structure having a relatively dense first transparent electrode layer and a relatively coarse and rough surface transparent electrode layer formed above the first transparent electrode layer, pixel defects with stable electrical and mechanical connection can be obtained. A liquid crystal display panel with a small amount can be manufactured at a high yield at a low cost.

Particularly, in the case of the second embodiment, the wiring electrode
Since the pixel electrode and the pixel electrode have exactly the same structure, the number of steps is merely increased by merely providing one extra transparent electrode layer having a rough surface. Such a simple solution is a conventional gold plating layer,
In other words, it is impossible by means of providing an opaque layer, and the present invention can be achieved for the first time by using a new means of adding a transparent electrode layer.

In recent years, with the demand for higher definition liquid crystal display panels, the width of the pixel electrodes and wiring electrodes has become smaller, the electrical resistance has increased, and the connection area between the wiring electrodes and other members has been reduced. Thus, the connection condition tends to be worse, but the present invention can respond to the request even in such a situation.

The method of providing a drive IC on a substrate as in the first and second embodiments enables high-density mounting and is most suitable for a high-definition liquid crystal display panel. Since the connection is made within a very small area, the stability of the connection is very important and the effect of the present invention is particularly large.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a liquid crystal display panel according to a first embodiment of the present invention.

FIG. 2 is a sectional view showing a liquid crystal display panel according to a second embodiment of the present invention.

FIG. 3 is a plan view showing a liquid crystal display panel in which a driving IC is face-down bonded on a substrate of the liquid crystal panel.

FIG. 4 is a sectional view showing a conventional liquid crystal display panel.

[Explanation of symbols]

 101 first substrate 102 second substrate 103 wiring electrode 104 pixel electrode 105 pixel electrode 106 driving IC 111 first transparent electrode layer 112 second transparent electrode layer 113 FPC

Claims (9)

(57) [Claims] The method according to claim 1] Two transparent substrates a transparent electrode layer is formed, the transparent electrode layer is provided with a gap as opposed disposed seals the periphery of the gap with a sealing material, the gap a liquid crystal panel constructed by a liquid crystal material is injected inside, small
The transparent electrode layer formed on at least one of the substrates
Is to form a pixel electrode inside the sealing material
In both cases, a wiring electrode is formed outside the sealing material.
In a liquid crystal panel in which another member is connected to at least a part of the wiring electrode, at least a portion of the wiring electrode connected to the other member
At least a first transparent electrode layer, the more becomes the multilayer structure and the second transparent electrode layer formed on the first transparent electrode layer above
And none, and transparent electrode layer of said second liquid crystal panel, characterized in that the coarse layer than the first transparent electrode layer. 2. The method according to claim 1, wherein the other member is for connecting an external circuit.
The liquid crystal panel according to claim 1, wherein the liquid crystal panel is an FPC . 3. The second transparent electrode layer of the wiring electrode
The liquid crystal panel according to claim 2, wherein the FPC is connected by an adhesive in which conductive particles are mixed in a resin. 4. The liquid crystal panel according to claim 1, wherein said another member is a semiconductor integrated circuit . 5. The semiconductor device according to claim 4, wherein the second transparent electrode layer of the wiring electrode and the semiconductor integrated circuit are connected by an adhesive in which conductive particles are mixed in a resin. LCD panel. And wherein said first transparent electrode layer and the second transparent <br/> electrode layer, any of claims 1 to 5 together, characterized in that consists of a layer of indium oxide and tin A liquid crystal panel according to claim 1. 7. The method according to claim 7, wherein the first transparent electrode layer is formed by sputtering.
Claim, characterized in that formed in the grayed method 1 to claim 6
The liquid crystal panel according to any one of the above. Wherein said second transparent electrode layer, a vacuum deposition method or
Or a sputtering method having different conditions from the first transparent electrode layer.
8. The method according to claim 1, wherein the first and second electrodes are formed by a metallization method.
The liquid crystal panel according to any one of the above. 9. The method according to claim 1, wherein the conductive adhesive is made of Ag resin.
/ Liquid crystal panel according to claim 3 or claim 5, characterized in that forming the entrained constituting the conductive particle made of Pd.