JPH06118429A - Liquid crystal display device and manufacturing method thereof - Google Patents

Abstract

(57) [Abstract] [Purpose] To prevent short-circuiting of metal wiring in a chip-on-glass liquid crystal display device. The wiring protection film 13 thicker than the alignment film 6 of the liquid crystal display unit 9 is made of the same material as the alignment film 6, and the metal wiring unit 11 is used.
Formed on. [Effect] With the wiring protection film having a sufficient thickness, the occurrence of a short circuit in the metal wiring portion due to scratches, foreign matter adhesion, Ag paste adhesion, etc. during the process is prevented, and the manufacturing yield is improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION This invention is a chip-on-glass.
The present invention relates to protection of a metal wiring portion and a method of forming a protective film in a liquid crystal display device of a (hereinafter, referred to as COG) system.

[0002]

2. Description of the Related Art In a COG type liquid crystal display device,
A metal wiring portion for input / output signals is provided on the substrate of the liquid crystal display element to mount a driving circuit element such as an LSI. The metal wiring portion has a multi-layer structure in which electrodes of a liquid crystal display portion made of, for example, ITO are extended and formed in a predetermined pattern up to a portion where a driving circuit element is mounted, and Cr, Al or the like is laminated thereon. However, since the layers are thin and the distance between the adjacent circuit patterns is narrow, there is a high possibility that a short circuit or the like will occur due to scratches or foreign matter adhered during the manufacturing process.
Further, during the manufacturing process of the liquid crystal cell, there is a process of printing the Ag paste for transfer by screen printing, but the Ag paste adheres to the metal wiring portion due to the pinhole of the screen, which may cause a short circuit. .

Providing a protective coating on the circuit pattern of the substrate itself is disclosed in, for example, Japanese Patent Publication No. 2-61428, but there is no mention of the film thickness for the purpose of preventing oxidation and solder outflow. Since it is considered to be extremely thin, the effect of preventing the short circuit due to the above scratches, foreign matter, Ag paste, etc. cannot be expected so much. In addition, Japanese Patent Publication No. 2-5729
No. 2 discloses forming a thin film made of the same material as the alignment film on the substrate, but this thin film prevents the conductive paste from adhering to the opposing substrates when the substrates are bonded together. However, it does not have a protective coating provided on the metal wiring portion, and has a different purpose.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and has an object to surely protect a metal wiring portion by providing a wiring protection film.

[0005]

In order to solve the above problems, in the liquid crystal display device of the present invention, the same material as the alignment film of the liquid crystal display portion is used in the liquid crystal display device having the structure of the chip-on-glass system. Is formed on the metal wiring portion provided on the substrate for connecting the driving circuit element, and the wiring protection film has a thickness larger than that of the alignment film, preferably 2000 Å or more. Selected as 10000Å. Further, in the method for manufacturing a liquid crystal display device of the present invention, when the alignment film is formed on the substrate on the side where the metal wiring portion for connecting the driving circuit element is formed, a portion corresponding to a region where the alignment film is to be formed is formed. The projection film occupancy rate is higher than that of the portion corresponding to the metal wiring part, and a single photosensitive resin plate is used. By printing the material in the same step, the alignment film of the liquid crystal display portion is formed, and the wiring protection film thicker than the thickness of the alignment film is formed on the metal wiring portion.

[0006]

Since the wiring protection film thicker than the alignment film is formed, the possibility of short circuit due to scratches, foreign matters, Ag paste, etc. is reduced, and the manufacturing yield is improved. In this case, if the wiring protection film is thinner than 2000Å, the film is likely to be broken due to penetration of foreign matter, and if it is thicker than 10000Å, uneven printing or outflow to the peripheral portion is likely to occur at the time of printing. When the thickness is set, sufficient performance as a wiring protection film can be obtained. Further, by making the projection occupancy rate of the portion corresponding to the formation region of the alignment film larger than that of the portion corresponding to the metal wiring part, the amount of the alignment film material deposited by printing is small on the alignment film side, and the metal wiring Since the size becomes larger on the part side, by printing with a single photosensitive resin plate, a wiring protective film thicker than the thickness of the alignment film can be formed on the metal wiring part without increasing the number of steps.

[0007]

EXAMPLE Next, one example shown in the figure will be described. In FIG. 1, 1 and 2 are glass substrates arranged at a predetermined interval, 3 and 4 are electrodes formed of ITO on the glass substrates 1 and 2, and 5 and 6 are formed on electrodes 3 and 4, respectively. The alignment film 7, the liquid crystal 7 and the seal material 8 form the liquid crystal display portion 9. Reference numeral 2a denotes a circuit forming portion formed by extending one glass substrate 2 to the outside of the liquid crystal display portion 9, and the electrode 4 has the circuit forming portion 2a.
And a metal layer 10 made of Cr, Al or the like is laminated thereon to form a metal wiring portion 11. Reference numeral 12 denotes a driving circuit element such as an LSI mounted on the circuit forming portion 2 a, which is connected to the metal wiring portion 11.

The above structure is similar to that of the conventionally known liquid crystal display device, but in the embodiment, the wiring protective film 13 is provided on the metal wiring portion 11 except for the pad portion for wire bonding. The difference is that The wiring protection film 13 is formed by printing the same material as the alignment film 6 at the same time when the alignment film 6 is formed on the glass substrate 2, and the thickness thereof is larger than that of the alignment film 6. .

As is well known, offset printing or flexographic printing transfers ink held between a large number of fine projections formed on a printing plate to a printing material, and the ink holding amount is the entire printing plate. It increases as the occupation ratio of the convex portion to the area decreases, and decreases as it increases. FIG. 2 shows a relief structure of a photosensitive resin plate 15 used for simultaneously forming the wiring protective film 13 and the alignment film 6 in this embodiment. Reference numeral 16 is an alignment film printing portion for forming the alignment film 6 on the glass substrate 2, 17 is a protective film printing portion for forming the wiring protective film 13 on the metal wiring portion 11, and the circles in the figure respectively. It is the figure which expanded and showed the relief structure of the alignment film printing part 16 and the protective film printing part 17. That is, the convex portion 16a is thick in the alignment film printing portion 16 and the convex portion 17a is thin in the protective film printing portion 17, so that the convex portion occupying ratio to the entire area is large in the alignment film printing portion 16, and the protective film printing portion 17 is large. Is getting smaller.

Therefore, when the polyimide solution is printed on the electrode 4 and the metal wiring portion 11 of the glass substrate 2 using such a printing plate 15, the amount of the polyimide solution held is small in the electrode 4 portion, and the metal wiring portion Because it is large in the 11th part,
The thin alignment film 6 and the thick wiring protection film 13 are printed at the same time, and after this printing, the alignment film 6 and the wiring protection film 13 are formed by baking in an oven at about 300 ° C. for several hours. The thickness of the alignment film 6 is the same as the conventional one, but the wiring protection film 13 is selected to be about 2000 Å to 10000 Å. This is because a sufficient wiring protection effect can be obtained within this range, whereas when the thickness is less than 2000 Å, the film is apt to be broken due to penetration of foreign matter or the like.
If it is thicker than Å, uneven printing or outflow to the peripheral area is likely to occur during printing.

Although the protrusions 16a and 17a of the photosensitive resin plate 15 are shown in FIG. 2 as having a cylindrical shape, the protrusions may have other shapes. Further, in the figure, the area ratio is changed by changing the thickness of the convex portions 16a and 17a, but it is also possible to change the convex portion occupation ratio by changing the depth of the groove between the convex portions. is there. Although the protective film printing portion 17 is drawn in a rectangular shape in FIG. 2, the wiring protective film 13 is actually formed except for the portion where the driving circuit element 12 is attached and the portion used for connection.

[0012]

As is apparent from the above-described embodiments, in the liquid crystal display device of the present invention, the wiring protection film thicker than the alignment film of the liquid crystal display section is formed on the metal wiring section by using the same material as the alignment film. It was formed in. Therefore, the wiring protection film having a sufficient thickness can prevent the occurrence of short-circuiting of the metal wiring portion due to scratches and foreign matter adhesion in the process, adhesion of Ag paste for transfer, and the like, and the manufacturing yield can be improved. Become. Further, the method for manufacturing a liquid crystal display device of the present invention uses a photosensitive resin plate in which the projection occupancy of the portion corresponding to the formation region of the alignment film is larger than that of the portion corresponding to the metal wiring portion, Since the alignment film and the wiring protection film are formed at the same time, a wiring protection film that is thicker than the thickness of the alignment film can be formed on the metal wiring portion without increasing the number of steps. The yield can be improved.

[Brief description of drawings]

FIG. 1 is a schematic sectional view of a main part of an embodiment of the present invention.

FIG. 2 is a perspective view of a photosensitive resin plate used in the same example.

[Explanation of symbols]

 1, 2 Glass substrate 5, 6 Alignment film 9 Liquid crystal display part 11 Metal wiring part 12 Driving circuit element 13 Wiring protective film 15 Photosensitive resin plate 16 Alignment film printing part 17 Protective film printing part 16a, 17a Convex part

Claims (2)

[Claims] 1. In a liquid crystal display device having a chip-on-glass structure, the same alignment film as that of the liquid crystal display unit is formed on a metal wiring part provided on a substrate for connecting a driving circuit element. A liquid crystal display device comprising a wiring protective film made of a material and thicker than an alignment film. 2. In the manufacturing process of a liquid crystal display device having a chip-on-glass system structure, an alignment film is formed when the alignment film is formed on a substrate on which a metal wiring portion for connecting a driving circuit element is provided. Area where the alignment film is formed by using a single photosensitive resin plate in which the occupancy ratio of the convex portion of the portion corresponding to the region to be formed is higher than the occupancy ratio of the convex portion of the portion corresponding to the metal wiring portion. By printing the alignment film material on both the metal wiring part and the metal wiring part in the same process, the alignment film of the liquid crystal display part is formed and the wiring protection film thicker than this alignment film is formed on the metal wiring part. A method for manufacturing a liquid crystal display device.