KR100672638B1 - Method of manufacturing Liquid Crystal Display Device - Google Patents

Abstract

The present invention is a step of preparing a lower substrate and an upper substrate; Forming a UV-curable seal material on any one of the above substrates; Dropping liquid crystal onto any one of the above substrates; Bonding the substrates together; Placing a mask on the upper side and the lower side of the bonded substrate so as to cover an area other than a region where the seal material is formed; And it relates to a method for manufacturing a liquid crystal display device comprising the step of curing the seal material by irradiating UV to the bonded substrate on which the mask is located,

According to the present invention, the seal material can be cured without adversely affecting device characteristics such as an alignment film and a thin film transistor formed on the substrate.

UV irradiation, mask

Description

Method of manufacturing liquid crystal display device

1 is a perspective view illustrating a manufacturing process of a liquid crystal display device by a conventional liquid crystal dropping method.

2A to 2D are perspective views illustrating a manufacturing process of a liquid crystal display device according to an exemplary embodiment of the present invention.

3 is a schematic layout showing a manufacturing process of a liquid crystal display device according to the present invention.

<Explanation of symbols for the main parts of the drawings>

1, 10: lower substrate 3, 30: upper substrate

5, 50: liquid crystal 7, 70: UV curing seal material

80: first mask 82: second mask

9, 90: light irradiation apparatus

The present invention relates to a liquid crystal display (LCD), and more particularly, to a method of manufacturing a liquid crystal display device by a liquid crystal dropping method.

Ultra-thin flat panel displays with a display screen thickness of only a few centimeters (cm). Among them, liquid crystal displays have low operating voltages, which consume less power and can be used as portable devices. Applications range from monitors to spacecraft to aircraft.

Such a liquid crystal display device generally includes a lower substrate on which a thin film transistor and a pixel electrode are formed, an upper substrate formed to face the lower substrate, and a light blocking film, a color filter layer, and a common electrode formed thereon; The liquid crystal layer is formed between the two substrates. An electric field is formed between the two substrates by the pixel electrode and the common electrode to drive the liquid crystal layer, and the light transmittance is adjusted through the driven liquid crystal layer. Will be displayed.

In the liquid crystal display device having such a structure, as a method of forming a liquid crystal layer between the lower substrate and the upper substrate, a vacuum injection method using a capillary phenomenon and a pressure difference is conventionally used. The manufacturing method of a liquid crystal display element is demonstrated.

First, a lower substrate including a thin film transistor and a pixel electrode, and an upper substrate including a light blocking film, a color filter layer, and a common electrode are manufactured.

In order to maintain a uniform cell gap between the two substrates, spacers are formed on one of the substrates, and a seal material is formed on one of the substrate edges to prevent liquid crystals from leaking out and to bond the two substrates. . In this case, as the seal material, a thermosetting seal material such as an epoxy seal material is mainly used.

Then, both substrates are bonded together. At this time, the epoxy seal material is a mixture of an epoxy resin and an initiator, and when heated, the epoxy resin activated by the initiator is polymerized through crosslinking to act as a seal material having excellent adhesion.

The bonded substrates are placed in a vacuum chamber to maintain the inside of the substrate in a vacuum state, and then immerse them in the liquid crystal. As such, when the inside of the substrate becomes a vacuum, the liquid crystal is sucked up into the inside of the substrate by a capillary phenomenon.

When the liquid crystal is filled to some extent inside the substrate, when nitrogen (N ₂ ) is gradually injected into the vacuum chamber, a pressure difference occurs between the inside of the substrate and the surroundings, and the liquid crystal fills the empty space inside the substrate. A layer is formed.

However, in this vacuum injection method, as the display screen becomes larger, the liquid crystal injection time takes a long time, resulting in a problem of low productivity.

Therefore, in order to solve the above problems, a new method called a liquid crystal dropping method has been proposed. Hereinafter, a method of manufacturing a liquid crystal display device by a conventional liquid crystal dropping method will be described with reference to the accompanying drawings.

1A to 1D are perspective views illustrating a manufacturing process of a liquid crystal display device by a conventional liquid crystal dropping method.

First, as shown in FIG. 1A, the lower substrate 1 and the upper substrate 3 are prepared. Although not shown in the drawing, a plurality of gate lines and data lines are formed on the lower substrate 1 to cross each other in a vertical direction, and a thin film transistor is formed at an intersection point of the gate line and the data line, and the thin film transistor is formed. A pixel electrode connected to the electrode is formed in the pixel region.

In addition, a light shielding film is formed on the upper substrate 3 to block light leakage from the gate wiring, data wiring, and thin film transistor forming regions, and a color filter layer of red, green, and blue is formed thereon. The common electrode is formed thereon. In addition, an alignment layer for initial alignment of liquid crystals may be formed on at least one of the lower substrate 1 and the upper substrate 3.

1B, the seal material 7 is formed on the lower substrate 1, and the liquid crystal 5 is dropped to form a liquid crystal layer. Then, the spacer for cell gap maintenance is dispersed on the upper substrate (3).

As shown in FIG. 1C, the lower substrate 1 and the upper substrate 3 are bonded to each other.

In this case, the above-described vacuum injection method of the liquid crystal display device is a bonding process of the two substrates before the liquid crystal is injected, the liquid crystal display device by the liquid crystal dropping method after the liquid crystal (5) dropping both substrates (1, 3) Since the bonding process of) is performed, when the thermosetting seal material is used as the seal material 7, the sealing material 7 flows while the seal material 7 is heated, thereby causing a problem in that the liquid crystal 5 is contaminated.

Therefore, in the liquid crystal display device by the liquid crystal dropping method, UV (Ultra Violet) hardening type sealing material is used as the sealing material 7.

And, as shown in Figure 1d, by irradiating UV through the UV irradiation device (9) to cure the seal material (7).

However, when UV is irradiated from the entire surfaces of the substrates 1 and 3 bonded in this way, the characteristics of devices such as thin film transistors formed on the substrate are adversely affected, and the pretilt angle of the alignment layer formed for the initial alignment of liquid crystals. (pretilt angle) is a problem that changes.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a method for manufacturing a liquid crystal display device for curing the seal material without adversely affecting the characteristics of the alignment film and the thin film transistor.

In order to achieve the above object, the present invention comprises the steps of preparing a lower substrate and an upper substrate; Forming a UV-curable seal material on any one of the above substrates; Dropping liquid crystal onto any one of the above substrates; Bonding the substrates together; Placing a mask on the upper side and the lower side of the bonded substrate so as to cover an area other than a region where the seal material is formed; And it provides a method for manufacturing a liquid crystal display device comprising the step of curing the seal material by irradiating UV to the bonded substrate on which the mask is located.

That is, the present invention is to irradiate UV only to the region where the seal material is formed and to block UV irradiation to other areas, thereby curing the seal material without adversely affecting the characteristics of the alignment film and the thin film transistor.

In addition, if the mask is formed on only one of the upper and lower sides of the bonded substrate and irradiated with UV, the same problem as described above may be caused by the UV reflected from the opposite side where the mask is not formed. Accordingly, the present invention is to prevent the irradiated UV from being irradiated to a region other than the seal material forming region by forming a mask on the upper side and the lower side of the bonded substrate.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

2A to 2D are perspective views illustrating a manufacturing process of a liquid crystal display device according to an exemplary embodiment of the present invention. Although only one unit cell is shown in the drawing, a plurality of unit cells may be formed on the substrate according to the size of the substrate.

First, as shown in FIG. 2A, the lower substrate 10 and the upper substrate 30 are prepared. Although not shown in the drawing, a plurality of gate lines and data lines are formed on the lower substrate 10 to cross each other in a vertical direction, and define a gate electrode, a gate insulating film, a semiconductor layer, A thin film transistor including an ohmic contact layer, a source / drain electrode, and a passivation layer is formed, and a pixel electrode connected to the thin film transistor is formed in the pixel area.

In addition, an alignment layer for initial alignment of liquid crystal is formed on the pixel electrode. In this case, the alignment layer may be formed by rubbing alignment treatment of a polyamide or polyimide compound, PVA (polyvinylalcohol), polyamic acid, or the like, or PVCN (polyvinylcinnamate) or PSCN (polyvinylcinnamate). Photoreactive materials such as polysiloxanecinnamate) or CelCN (cellulosecinnamate) -based compounds may be formed by photoalignment treatment.

Although not shown in the drawings, a light shielding film is formed on the upper substrate 30 to block light leakage from the gate wiring, data wiring, and thin film transistor forming regions, and a red, green, and blue color is formed on the light blocking film. A color filter layer is formed, and a common electrode is formed on the color filter layer. In addition, an overcoat layer may be further formed between the color filter layer and the common electrode. In addition, the alignment layer described above is formed on the common electrode.

In addition, silver (Ag) is formed in a dot shape on the outer portion of the lower substrate 10 to apply voltage to the common electrode on the upper substrate 10 after the bonding of the substrates 10 and 30. Do it.

In the case of an In Plane Switching (IPS) mode liquid crystal display device, the common electrode is formed on the same lower substrate as the pixel electrode to induce the transverse electric field, and the silver dot is not formed.

As shown in FIG. 2B, a liquid crystal layer is dropped on the lower substrate 10 to form a liquid crystal layer, and a screen printing method or a dispenser method is formed at an edge of the upper substrate 30. UV-curable seal member 70 is formed in a closed pattern without an injection hole.

At this time, if the liquid crystal 50 meets the seal material 70 before the seal material 70 is cured in a later process, the liquid crystal 50 is contaminated, so that the liquid crystal 50 is placed at the center of the lower substrate 10. Dropping As such, the liquid crystal 50 dropped in the central portion is gradually spread until the seal material 70 is cured, and is distributed at the same density throughout the substrate.

Meanwhile, the present invention is not limited thereto, and the liquid crystal 50 may be formed on the upper substrate 30, and the UV-curable seal material 70 may be formed on the lower substrate 10. In addition, the liquid crystal 50 and the UV-curable seal material 70 may be formed on the same substrate. However, when the liquid crystal 50 and the UV-curable seal material 70 are formed on the same substrate, an imbalance occurs between the process between the liquid crystal and the UV-curable seal material and the substrate on which the UV-curable seal material is formed. Since the liquid crystal and the seal material are formed on the same substrate, even if a contaminant is formed on the seal material before bonding, the substrate cannot be cleaned. Therefore, the liquid crystal and the seal material are preferably formed on different substrates.

Therefore, as shown in FIG. 2B, after the UV-curable seal material 70 is formed on the upper substrate 30, a cleaning process for cleaning the upper substrate 30 before the bonding process, which is a post process, may be further performed.

In this case, the UV-curable seal material 70 is used by mixing monomers or oligomers having an acrylic group bonded to both ends with an initiator, or mixing monomers or oligomers having an acrylic group bonded to an acrylic group at one end thereof with an initiator. It is preferable to use.

In addition, although not shown in the drawings, a spacer for maintaining a cell gap may be formed on any one of the substrates 10 and 30, preferably the upper substrate 30.

The spacers may be formed by mixing the ball spacers in a solution at an appropriate concentration and then spreading them on the substrate at a high pressure with a spray nozzle. The spacers may be formed by attaching a column spacer onto a substrate corresponding to the gate wiring or data wiring forming region. However, since the ball spacer has a disadvantage in that the cell gap is uneven when applied to a large area, it is preferable to form a column spacer on the large area substrate.

In this case, it is preferable to use a photosensitive organic resin as the column spacer.

As shown in FIG. 2C, the lower substrate 10 and the upper substrate 30 are bonded to each other. In the bonding process, one substrate on which the liquid crystal is dropped is fixed to the lower surface of the two substrates, and the other substrate is rotated 180 degrees so that the layer forming surface faces the one substrate, and then placed on the upper surface. The two substrates may be bonded by applying pressure to one positioned substrate, or the two substrates may be bonded by releasing the vacuum after forming a vacuum between the spaced two substrates.

As shown in FIG. 2D, the mask 80 may be formed on the upper side and the lower side of the bonded substrate by placing the first mask 80 and the second mask 82 on a portion other than the region where the UV-curable seal material 70 is formed. 82) and irradiates UV through the UV irradiation device (90).

At this time, the drawing shows only the case where the UV irradiation apparatus 90 is formed on the upper side of the bonded substrate, but the UV irradiation apparatus 90 may be formed on the lower side of the bonded substrate. In addition, although only the case of UV irradiation to the upper substrate 30 surface of the bonded substrate is shown in the figure, it is also possible to rotate the bonded substrate to UV irradiation to the lower substrate 10 surface.

As described above, the present invention can prevent the UV from being reflected and irradiated to a region other than the seal material forming region by forming a mask on the upper side and the lower side of the bonded substrate and irradiating UV. In addition, by performing the UV irradiation to the inside and outside of the bonded substrate by configuring the equipment to reflect the UV irradiation intentionally, it is possible to increase the UV irradiation efficiency to promote the curing of the UV-curable seal material (70).

When UV is irradiated as described above, the lower substrate 10 and the upper substrate 30 are adhered to each other by polymerizing a monomer or oligomer activated by an initiator constituting the UV-curable seal material.

In this case, when the monomer or oligomer having an acrylic group bonded to an acrylic group at one end of the UV-curable seal material is mixed with an initiator with the initiator, the epoxy group does not react by such UV irradiation. Furthermore, a heating process is performed and the sealing material is completely hardened. The heating step is preferably performed for about 1 hour at about 120 ℃.

Although not shown in the drawings, a process of cutting a substrate into a unit cell and a final inspection process are performed after the UV irradiation process.

In the process of cutting the substrate using the unit cell, a diamond pen having a hardness higher than that of glass is used to form a cutting line on the surface of the substrate (scribing process), and then, a mechanical force is applied to cut the substrate along the cutting line. Break process: It may be performed by a break process, or a scribe and brake process may be performed as a single process by forming a diamond pen into a sawtooth shape.

The final inspection process is a process of confirming whether the substrate cut in the cell unit is defective before assembling into the liquid crystal module. The final inspection process checks whether each pixel is properly driven when voltage is applied or no voltage is applied.

3 is a schematic layout showing a manufacturing process of the liquid crystal display device according to the present invention described above.

As shown in FIG. 3, the present invention prepares an upper substrate, forms an alignment layer thereon, and then forms a seal material thereon to complete the upper substrate. In addition, a lower substrate is prepared, an alignment layer is formed thereon, and then a liquid crystal is dropped thereon to complete the lower substrate. At this time, the manufacturing process of the upper substrate and the lower substrate is carried out at the same time, the liquid crystal and the seal material can be selectively formed on the substrate as described above.

Then, after bonding the finished positive substrate, and then irradiated with UV to cure the seal material, cut the substrate by a cell unit, and performs a final inspection process to complete one liquid crystal cell.

The present invention is not limited to the above embodiments, but may be modified within the scope obvious to those skilled in the art.

In the present invention, by forming a mask on the upper side and the lower side of the bonded substrate and irradiating UV, UV is irradiated only to the region where the UV-curable seal material is formed and UV irradiation is blocked to other regions, thereby damaging the alignment layer formed on the substrate. Device characteristics such as thin film transistors are not deteriorated.

In addition, by irradiating UV on the surface of the bonded substrate and other areas to reflect the partially irradiated UV, it is possible to increase the UV irradiation efficiency to promote the curing of the UV-curable seal material.

Claims (10)

Preparing a lower substrate and an upper substrate; Forming a UV curable seal material on the upper substrate; Dropping liquid crystal onto the lower substrate; Bonding the upper substrate and the lower substrate together; Placing a mask on the upper side and the lower side of the bonded substrate so as to cover an area other than a region where the seal material is formed; And And hardening the seal material by irradiating UV to the bonded substrate on which the mask is located. The method of claim 1, The seal material is a method of manufacturing a liquid crystal display device, characterized in that formed using a monomer or oligomer having an acrylic group bonded to both ends. The method of claim 1, The seal material is a method of manufacturing a liquid crystal display device, characterized in that formed using a monomer or oligomer having an acrylic group at one end, and an epoxy group at the other end. delete delete delete delete The method of claim 1, And forming a column spacer on any one of the above two substrates. The method of claim 8, The column spacer is formed on the upper substrate. delete

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