JPS6363021A - Display device - Google Patents

Abstract

PURPOSE:To improve the adhesiveness of a thin conductive film and conductive adhesive agent deposited on the inside surface of a glass substrate and to improve the reliability of electrical and mechanical connections by subjecting the inside surface layer of the glass substrate to a treatment for dissolving and removing the alkali component and alkaline earth metallic oxide. CONSTITUTION:The upper glass substrate plate 1 and lower glass substrate plate 2 are immersed into an etching soln., by which the alkali component and alkaline earth metallic oxide are eluted from the surfaces of the glass substrates to leave only the skeleton structure of silicon oxide, etc., and to form fine ruggedness on the surface. The surfaces of underlying films 3 consisting of the silicon oxide formed thereon and the upper plate electrode 4 and lower plate electrode 5 consisting of ITO films can, therefore, maintain nearly the same rugged shapes as the rugged shapes of the glass substrates 1, 2. The adhesive area of the silver epoxy conductive adhesive agent 10 and the upper plate electrode 4 and lower plate electrode 5 is thereby increased, by which the mechanical adhesive power is intensified and the electrical connection characteristic is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an optical display device such as a liquid crystal display device, a plasma display device, or an active matrix type liquid crystal display device.

[Conventional technology]

In both of these flat display devices, two glass substrates coated with a conductive thin film such as a transparent conductive film are placed facing each other with the conductive thin film on the inside, and a conductive adhesive is used to connect the two glass substrates. It has a basic structure in which the conductive thin films of both are mechanically fixed and electrically connected.

FIG. 2 is a schematic cross-sectional view of a conventionally used liquid crystal display device. Although the figure shows only a part, this liquid crystal display device includes an upper glass substrate 1 and a lower glass substrate 2.
It has two glass substrates arranged opposite to each other. A base film 3 is formed on the inner surface of each glass substrate in order to prevent diffusion of alkaline components from the glass, and on top of this,
An upper glass substrate 1 and a lower glass substrate 2 are formed with an upper electrode 4 for displaying an arbitrary pattern on the upper glass substrate 1 side and a lower electrode 5 as a common electrode on the lower glass substrate 2 side. The gap between the spacer 7 in the sealing material 6 and
It is set uniformly to υ5 to 10 μm. In addition, the peripheral substrate 1
, 2 is provided with an alignment film 8, and the surface thereof is subjected to an alignment treatment such as rubbing. A liquid crystal 9 is sealed in between. Here, the lower plate electrode 5 is electrically connected to a part of the upper plate electrode 4 via a conductive adhesive 10 (Japanese Patent Laid-Open No. 49-6
0190 Publication, % Publication No. 51-57189, Japanese Patent Publication No. 51-65898, Japanese Patent Publication No. 52-120792
When displaying characters, etc., select the upper plate electrode 4 corresponding to the pattern and apply a predetermined voltage between it and the lower plate electrode 5, so that the liquid crystal molecules in that part are aligned. Due to the relationship with polarizers and analyzers which are arranged in the direction and are arranged on the outside of both the upper and lower substrates 1 and 2 (not shown in the figure), only that portion is displayed in black.

[Problem that the invention seeks to solve]

In such a liquid crystal display device, the contact area between the upper plate electrode 4 and the lower plate electrode 5 and the conductive adhesive 10 is generally 0.2
~0.6 rrrrhφ or as small as the mouth. Moreover, the surfaces of the upper plate electrode 4 and the lower plate electrode 5 in contact with the conductive adhesive 10 vary depending on the method of forming the electrode film.
For example, if a sputtering method is used, which is preferable because it is relatively inexpensive and can form a film with low resistance, it is deposited in an atomic state and has excellent smoothness. The adhesive force is weak and a stable connection cannot be obtained.

For this reason, there is a problem in that a contrast difference occurs due to a difference in connection resistance, especially during low voltage operation in a high time division/high frequency region.

Conventionally, countermeasures have been taken, such as modifying the ingredients of the conductive adhesive, but they lack stability and when the conductive adhesive is crushed while being heated, the resin escapes to the outside.
This method has disadvantages such as metal particles gathering in the center and making the columnar metal part difficult to crush, and is not necessarily an effective solution.

An object of the present invention is to provide a display device that improves the adhesion between a conductive adhesive and a highly conductive thin film adhered to the inner surface of a glass substrate, thereby increasing the reliability of electrical and mechanical connections. do.

[Means for solving problems]

The above problem can be solved by subjecting the inner surface device of the glass substrate to a treatment for dissolving and removing alkali and alkaline earth metal oxides, leaving only the skeleton structure mainly composed of silicon oxide.

Here, the surface layer of the glass substrate refers not only to the original surface of the glass substrate itself, but also to the underlying layer when a base film such as silicon oxide is baked on the surface to prevent the diffusion of alkaline components. It also includes the surface of the glass substrate having a base film and the surface portion of the base film.

[Effect]

The surface layer of the glass substrate, where only the skeletal structure remains, has increased irregularities,
The area bonded by the conductive adhesive increases.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings.

In FIG. 1, the same reference numerals as in FIG. 2 indicate the same or corresponding parts, and the liquid crystal display device of this embodiment basically has a second
It has the same configuration as the conventional example shown in the figure.

However, here, as the upper glass substrate 11 and the lower glass substrate 12, substrates having extremely fine irregularities on their inner surfaces are used.

Such glass substrates can be etched using an etching solution containing, for example, an aqueous solution of silica containing hydrofluorosilicic acid as a main component, or an etching solution to which boric acid and potassium heptadide are added. using 25~
It can be easily formed by immersing it in this etching solution at 40°C for about 30 to 200 minutes. That is,
By immersing it in the above etching solution, alkali components such as Na2O, 20, etc. and Mlo,
Alkaline earth metal oxides such as CaO are eluted, and only skeleton structures such as silicon oxide, which are difficult to dissolve in the etching solution, remain, forming fine irregularities on the surface.

In this way, the glass substrate 11 with only the skeletal structure left on the surface layer
．． By using the glass substrate 11.12, the surfaces of the base film 4 made of silicon oxide formed thereon and the upper plate electrode 4 and lower plate electrode 5 made of ITO film also become similar to the glass substrate 11.12.
It is possible to maintain an uneven shape that is almost the same as that of the surface.

Therefore, the adhesion area between the silver epoxy conductive adhesive 10 and the upper plate electrode 4 and lower plate electrode 5 is increased by several tens to hundreds of times compared to the conventional structure shown in FIG. Mechanical adhesion is strengthened, and electrical readability is also improved.

As a result, local contrast defects in high time division, high frequency, and low voltage regions are less likely to occur, and mechanical vibrations and
Peeling of the interface between the electrode 4.5 and the conductive adhesive 10 due to temperature cycling or the like can also be prevented, and the reliability of the electrical connection is improved.

It goes without saying that the upper plate electrode 4 and the lower plate electrode 5 are not limited to the ITO film, but may be other conductive thin films such as a 5n02 film. Similarly, the conductive adhesive 10 is not limited to silver epoxy.

In addition, on the outer main surfaces of the upper glass substrate 1 and the lower glass substrate 2, there are fixed display contents such as a frame with a polarizer or analyzer glued to it, a frame, and letters and numbers that should be displayed at all times. Printed page. Therefore, by subjecting the outer main surfaces of both substrates to the same treatment as the inner main surfaces and making them uneven, it is possible to improve their adhesion and printability.

The liquid crystal display device described above is a liquid crystal display device of the accu-dip matrix type using TPT (thin film transistor) play, or a plasma display device, etc., in which two glass substrates coated with conductive thin films are placed facing each other and conductive. The present invention can be similarly applied to a display device having a configuration in which both conductive thin films are electrically connected by a conductive adhesive.

〔Effect of the invention〕

According to the present invention, the roughness of the glass substrate surface is increased, the surface area is increased, and the contact area with the conductive adhesive is sufficiently large, so that the reliability of mechanical and electrical connections is improved. For example, with regard to liquid crystal display devices, it is difficult to prevent contrast unevenness during low voltage driving in high time division and high frequency regions.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing one embodiment of the present invention, and FIG. 2 is a sectional view showing a conventional example. 1.2@11+1-glass substrate, 4,5... pot/electrode,
10... Conductive adhesive. 1≧＼ Agent Patent Attorney Masao Ogawa- ＼-1-l Figure 1 Figure 2

Claims (1)

[Claims] 1. In a display device in which two glass substrates coated with conductive thin films are placed facing each other with the conductive thin films on the inside, and the two conductive thin films are mechanically and electrically connected using a conductive adhesive. . A display device, wherein at least the inner surface layer of the glass substrate is subjected to a treatment for dissolving and removing alkali and alkaline earth metal oxides, leaving only the skeletal structure.