JPH0827461B2 - Liquid crystal display panel and manufacturing method thereof - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to a liquid crystal display panel used for an automobile instrument panel and OA equipment, and in particular, a liquid crystal in which a driving electronic circuit element is integrally mounted, an EL, etc. The present invention relates to a liquid crystal display panel and a manufacturing method thereof.

[Conventional technology]

In recent years, a graphic display has been widely used as a man-machine interface, and along with this, a liquid crystal display device has also been used in an instrument panel of an automobile, which is accompanied by the practical use of a color liquid crystal display element. It tends to be further accelerated.

By the way, in such a liquid crystal display device (hereinafter, referred to as a liquid crystal display panel), the panel-shaped form is utilized, one of the electrode substrates is expanded, and then the electronic circuit element for driving ( LSI) is directly mounted and both are modularized. Incidentally, as for such an example, for example, JP-A-53-60199 and JP-A-53-60
It is disclosed in Japanese Patent Publication No. 104198 and the like.

Therefore, a conventional example of such a liquid crystal display panel will be described with reference to FIG.

FIG. 2 shows a liquid crystal display panel composed of a glass substrate 1 and a glass substrate 2 which is an electrode substrate.
An LSI chip 4 for driving a liquid crystal display panel is fixed on the glass substrate 2 with an adhesive 5, and Au and Al
It is mounted by a method of connecting to a wiring circuit using the wire line 6. The metal wiring 7 between the liquid crystal display unit and the terminals of the LSI chip 4 and the metal wiring 8 between the terminals of the LSI chip 4 and the terminals for connecting the external circuit are made of the same conductor material, for example, Cr.
-A conductor layer including a Cu2 layer film or an Al film is used.

Further, in FIG. 2, reference numeral 3 is a sealant for sealing the liquid crystal sandwiched between the glass substrates 1 and 2. Although it is omitted in FIG. 2 because it is difficult to show, a protective resin is actually provided to cover the LSI chip 4.

Next, FIG. 3 is a sectional view taken along the line AA ′ in FIG. 2, in which FIG.
Is a sealant, 4 is an LSI chip, 5 is an adhesive, 6 is a wire wire, 7 and 8 are metal wiring, and a Cr-Cu2 layer film or A
It consists of a membrane. Reference numeral 9 is a liquid crystal layer, and 10 and 11 are transparent electrodes made of a transparent conductive film made of In ₂ O ₃ , SnO ₂ or a mixture thereof.

By the way, in a liquid crystal display panel mounted with an LSI chip having such a structure, various types of reliability are required.
The reliability evaluation is divided into two types, a non-energization reliability test and an energization reliability test. The energization reliability test is an operation test of the liquid crystal display panel under various conditions.

First, during the non-energization reliability test, it was left at high temperature (90 ° C-
500h), high temperature and high humidity (70 ℃ / 95% RH-1000h), temperature / humidity cycle Temperature cycle There is a vibration test (10G, 10 to 500Hz-100h each).

Therefore, the above-mentioned various non-energization reliability tests were performed on the conventional liquid crystal display panel having the structure shown in FIGS. 2 and 3. As a result, it was found that the corrosion of the wiring was observed in the high temperature and high humidity test, and the target specifications were not satisfied.

In the above conventional liquid crystal display panel, normally,
A synthetic resin film such as an epoxy resin is formed on the surface of the metal wiring to protect the metal wiring. However, such a synthetic resin film does not have sufficient moisture resistance, and thus the high temperature and high humidity as described above. It is not possible to effectively prevent corrosion of the underlying metal wiring.

Therefore, in the conventional liquid crystal display panel as described above, in the high temperature and high humidity test, the metal wiring is corroded, disconnection of the wiring occurs over a long period of time, leading to display failure,
It significantly reduces the reliability of the liquid crystal display panel and is incomplete as a product.

[Problems to be solved by the invention]

As described above, the conventional liquid crystal display panel has a problem that it is difficult to sufficiently maintain the required reliability when it is applied to an automobile or the like.

The object of the present invention is to solve the above-mentioned problems of the prior art,
An object of the present invention is to provide a liquid crystal display panel which is free from corrosion of wiring even under high temperature and high humidity, and which can maintain sufficient reliability even when used in a display device such as an automobile.

[Means for solving problems]

To achieve this object, the present invention forms a thin, substantially non-porous oxide film on the surface of a liquid crystal display panel equipped with electronic circuit elements by subjecting the metal wiring to electrolytic treatment in a neutral aqueous solution. The main idea is to do.

That is, the first invention of the present invention is an invention relating to a liquid crystal display panel, and the gist thereof is, "One of the electrode substrates of the display element is expanded to be a wiring board, and the wiring board is provided with electronic elements for driving the display element. In a liquid crystal display panel on which a circuit element is mounted, the wiring forming the circuit element is composed of a conductor having a substantially non-porous oxide film formed on its surface. " A second invention of the present invention is an invention relating to a method for manufacturing the liquid crystal display panel, the gist of which is, "One of the electrode substrates of the display element is expanded to be a wiring board, and this wiring board is used for driving the display element. In a method of manufacturing a liquid crystal display panel mounted with an electronic circuit element, after forming wiring on a wiring board, the wiring is made by a neutral electrolytic solution,
A method of manufacturing a liquid crystal display panel, which comprises forming a substantially non-porous oxide film on the surface of the wiring by performing an electrochemical treatment. "It is in.

The present invention as described above is based on the following findings. That is, the inventors of the present invention think that in order to prevent the corrosion of the metal wiring as described above as a problem of the prior art, it is not necessary to first contact with water, and an organic substance or an inorganic substance is formed on the metal wiring. Considered coating. Therefore, as a method of pinhole test of the material to be coated on the wiring, that is, a method of evaluating the throwing power on the wiring, a polyimide resin is coated on the wiring, water drops are applied on the surface, and then a voltage is applied to the metal wiring. Then, the dissolved state of the wiring was checked. At that time, in the case of Al wiring, it was found that the melting current did not flow even if the polyimide resin had pinholes.

This phenomenon was presumed to be due to the fact that the Al wiring surface in contact with the aqueous solution was sufficiently dense, that is, a substantially non-porous oxide film was generated from the viewpoint of moisture resistance or corrosion resistance, preventing dissolution. . Therefore, the Al wiring was electrolytically treated with a neutral aqueous solution, that is, the Al wiring was made into a pole and a DC voltage of 50 V was applied. When this sample was exposed to high temperature and high humidity (70 ℃ / 95% RH), it was discovered that no corrosion of Al wiring occurred. That is, it was clarified that the electrolytic treatment of the Al wiring in the neutral aqueous solution produces the substantially non-porous oxide film on the surface, which is effective for the corrosion prevention.

The results are shown below. FIG. 4 shows a test pattern for a high temperature and high humidity test. This pattern has a comb structure so that only one side pattern can be selectively electrolytically treated. Therefore, using Al as the wiring material, the pattern shown in FIG. 4 was produced. Therefore, next, pure water (pH = 7.0) was used as an electrolytic solution, one side terminal of the pattern in FIG. Therefore, the other putter is not electrolytically treated. The high temperature and high humidity test pattern thus produced was subjected to a high temperature and high humidity test (70 ° C./95% RH), which is a reliability evaluation test. As a result, it was confirmed that, after 506 hours of the high temperature and high humidity test, corrosion was not generated in the Al patterns which were alternately subjected to the electrolytic treatment. On the other hand, the Al pattern not subjected to electrolytic treatment was completely corroded. Thus, it was confirmed that the electrolytic treatment with the neutral aqueous solution prevents corrosion of the Al wiring and improves the reliability. The reason why this corrosion is prevented is considered to be that a thin and dense oxide film is formed on the Al surface by the electrolytic treatment, and the results of examining the film thickness of the oxide film are shown in FIG. The vertical axis of FIG. 5 represents the film thickness of the oxide film, and the horizontal axis represents the applied voltage. Pure water (pH = 7.0) was used as the electrolytic solution, and the application time was 60 seconds. Moreover, it has been confirmed that the electrolytic current flows rapidly when a voltage is applied, but immediately drops and almost stops flowing. Therefore, the generated film thickness of the oxide film is proportional to the applied voltage.

Since the sample subjected to the high temperature and high humidity test described above has an applied voltage of 50 V, the thickness of the oxide film is approximately 400 Å (see Fig. 5), and even with this thickness, it is possible to withstand reliability sufficiently. It was confirmed. Furthermore, a high temperature and high humidity test (70 ° C / 95% RH) for reliability evaluation of a sample with an oxide film thickness of 300Å
As a result, it was confirmed that no corrosion of Al wiring was observed. Therefore, it was confirmed that the minimum thickness of the oxide film should be 300 Å or more.

As described above, in the present invention, the oxide film formed on the surface of the wiring constituting the circuit element has a sufficient density to impart sufficient corrosion resistance under high temperature and high humidity to the wiring, that is, moisture-proof. It is substantially non-porous from the viewpoint of corrosion resistance and corrosion resistance. And such a non-porous oxide film is formed by using a neutral electrolyte as an electrolytic solution in the electrochemical treatment,
In the case of a well-known alumite having an acidic electrolyte of 0.4 or less, the oxide film formed is 300 Å ~ 400
It will be porous with Å holes, and it will not be possible to obtain the desired compactness. Further, such a porous oxide film also does not have the required performance in terms of electrical insulation.

Although the case where Al is used as the material for forming the wiring has been described above, Cu, Ti, and the like can be similarly used as the material for forming the wiring in the present invention in addition to Al.

[Action]

The present invention, as described above, electrolytically treats the wiring formed on the wiring substrate in a neutral aqueous solution, and the surface thereof is sufficiently dense, that is, substantially non-porous from the viewpoint of moisture resistance or corrosion resistance. By forming the oxide film, corrosion of the wiring under high temperature and high humidity is prevented. Then, it was confirmed that since the disconnection and the short circuit of the wiring are eliminated by this, malfunction such as display defect is eliminated and reliability is improved.

〔Example〕

Hereinafter, a liquid crystal display panel according to the present invention will be described in detail with reference to illustrated embodiments.

FIG. 1 shows an embodiment of the liquid crystal display panel of the present invention. In FIG. 1, 1 and 2 are glass substrates, 3 is a sealant, and 4 is an LSI.
Chips, 5 is an adhesive, 6 is a wire line, 7 and 8 are metal wirings, 9 is a liquid crystal layer, and 10 and 11 are transparent electrodes made of a transparent conductive film made of In ₂ O ₃ , SnO ₂ or a mixture thereof. .

12 and 13 are oxide film layers, which are formed on the surfaces of the metal wirings 7 and 8. 14 is a coating resin for protecting the LSI chip.

The liquid crystal display portion 100 has a structure in which the liquid crystal layer 9 is sandwiched between the glass substrate 1 and the glass substrate 2. A transparent electrode 10 is formed on the glass substrate 1, and a transparent electrode 11 is formed on the glass substrate 2. The transparent electrode 11 is exposed from the liquid crystal display element portion to the outside, where the metal wirings 7 and 8 are partially laminated to secure electrical connection.

According to the present invention, since the dense oxide film layer is provided on the surfaces of the metal wirings 7 and 8, in the high temperature and high humidity test, corrosion is prevented, the wiring is not melted or broken, and the reliability is improved. I was able to measure.

Table 1 shows the high temperature and high humidity test results of the liquid crystal display panel according to this example.

In Table 1, for comparison, the metal wiring is Cr-Cu2.
A liquid crystal display panel composed of a layer film and an Al (without electrolytic treatment) film is shown together. In Table 1, the thickness of the metal wirings 7 and 8 in the embodiment shown in FIG. 1 is constant at 2.0 μm.
Among these, the thickness of the oxide film layer on the Al wiring in this example is
It is 150,300,430Å.

As is clear from this, the high temperature and high humidity test (70/95% RH
-1000 hours), the oxide layer thickness should be 30
It was confirmed that 0 Å or more is sufficient.

If necessary, a protective film made of epoxy resin or the like may be further formed on the surface of the oxide film to further protect the wiring surface from contamination and the like.

In the present invention, electrolytic treatment in a neutral aqueous solution forms a dense oxide film layer on the wiring surface to prevent the wiring from being corroded by water.However, if the metal wiring is not electrolytically treated, It is very effective if there is an electrolytic solution that forms a dense film on the surface of the metal wiring only by immersing it in the solution.

As a characteristic of such an electrolytic solution, it is considered that a neutral solution is better than a weak acid or alkaline solution.

Furthermore, if a conductive resin can be adopted as the wiring material of the liquid crystal display panel, it is considered that there will be no problem of corrosion under high temperature and high humidity.

〔The invention's effect〕

As described above, according to the present invention, since it is possible to eliminate the corrosion of the metal wiring in the liquid crystal display panel having the electronic circuit element mounted thereon, it is possible to solve the problems of the prior art and also to expect the improvement of the yield. A display panel that can maintain sufficient reliability for automobiles and the like can be obtained.

[Brief description of drawings]

FIG. 1 is a sectional view of an embodiment of the liquid crystal display panel of the present invention,
FIG. 2 is a perspective view of an example of a conventional liquid crystal display panel, and FIG.
FIG. 4 is a sectional view taken along the line AA ′ in FIG. 2, FIG. 4 is a schematic diagram showing a test pattern for high temperature and high humidity test, and FIG. 5 is a characteristic diagram showing a relation between an oxide film thickness and an applied voltage during electrolysis. Is. 1,2 …… Glass substrate, 3 …… Sealant, 4 …… LSI chip,
5 ... Adhesive, 6 ... Wire wire, 7,8 ... Metal wiring, 9
...... Liquid crystal layer, 10,11 ...... Transparent electrode, 12,13 ...... Oxide layer, 14
…… Coating resin, 100 …… LCD display

Claims (6)

[Claims] 1. A liquid crystal display panel in which one of the electrode substrates of a display element is expanded to form a wiring board, and an electronic circuit element for driving the display element is mounted on the wiring board. A liquid crystal display panel characterized by comprising a conductor having a non-porous oxide film formed on its surface. 2. The wiring is an Al wiring, and the oxide film is an aluminum oxide film.
The liquid crystal display panel according to the item. 3. The liquid crystal display panel according to claim 1 or 2, wherein the oxide film has a thickness of 300 Å or more. 4. A method of manufacturing a liquid crystal display panel in which one of the electrode substrates of a display element is expanded to form a wiring board, and an electronic circuit element for driving the display element is mounted on the wiring board. After the formation, the wiring is subjected to an electrochemical treatment with a neutral electrolytic solution to form a substantially non-porous oxide film on the surface of the wiring, which is a method for manufacturing a liquid crystal display panel. 5. The neutral electrolyte has a hydrogen ion concentration of 6 to 8.
The method for producing a liquid crystal display panel according to claim 4, which is an aqueous solution in the range of (pH = 6 to 8). 6. The wiring according to claim 4, wherein the wiring is an Al wiring and the oxide film is an aluminum oxide film.
Item 6. A method for manufacturing a liquid crystal display panel according to item 5 or 5.