KR20120066519A

KR20120066519A - Method of fabrication electrophoretic display device

Info

Publication number: KR20120066519A
Application number: KR1020100127893A
Authority: KR
Inventors: 권오남; 임유석
Original assignee: 엘지디스플레이 주식회사
Priority date: 2010-12-14
Filing date: 2010-12-14
Publication date: 2012-06-22

Abstract

PURPOSE: An electrophoresis display device manufacturing method is provided to reduce manufacturing costs by directly forming an electrophoresis layer on a substrate. CONSTITUTION: A partition wall(180) is formed on a protection layer. A pixel electrode(118) is formed in a display unit. An electrophoresis material is spread on the display unit by using a screen mask. An electrophoresis layer(160) is formed. The common electrode is formed on a second substrate. The first substrate is arranged on the second substrate.

Description

Manufacturing Method of Electrophoretic Display Device {METHOD OF FABRICATION ELECTROPHORETIC DISPLAY DEVICE}

The present invention relates to a method of manufacturing an electrophoretic display device.

In general, an electrophoretic display device is an image display device using a phenomenon in which colloidal particles move to either polarity when a pair of electrodes to which voltage is applied is immersed in a colloidal solution. A wide viewing angle, high reflectance, and low consumption without using a backlight Since it has characteristics, such as an electric power, it is attracting attention as an electronic device, such as an electric paper.

The electrophoretic display device has a structure in which an electrophoretic layer is interposed between two substrates, one of the two substrates is made of a transparent substrate, and the other is composed of an array substrate on which a driving element is formed, thereby reflecting input light. The image can be displayed in the reflective mode.

1 is a view showing the structure of a conventional electrophoretic display device (1).

As shown in FIG. 1, the electrophoretic display device 1 includes a first substrate 20 and a second substrate 40 including a plurality of pixel regions, and an image display portion of the first substrate 20. A partition wall formed between the pixel electrode 18, the common electrode 42 formed on the second substrate 40, and an image non-display portion between the pixel and the pixel area of the second substrate 40 to partition each pixel. 80 and an electrophoretic layer 60 formed between the first substrate 20 and the second substrate 40.

Although not shown in the drawing, a thin film transistor is formed in each pixel region, and an electric field is formed between the pixel electrode 18 and the common electrode 42 as a voltage is applied to the pixel electrode 18. The second substrate 40 including the 60 is bonded to the first substrate 20 by an adhesive layer. The electrophoretic layer 60 is composed of an electrophoretic material in which white particles 64 and black particles 65 having positive and negative charge characteristics, respectively, are dispersed in a dispersion medium 62.

In the electrophoretic display device having such a structure, since the white particles 164 have positive charge characteristics, when the positive voltage is applied to the pixel electrode 18 from the outside, the common electrode 42 has a relatively negative potential. Therefore, the white particles 64 having a positive charge move toward the common electrode 42. Therefore, when light is input from the outside, that is, the upper portion of the second substrate 40, the input light is mostly reflected by the white particles 64, so that white is implemented in the electrophoretic display device.

On the contrary, when a negative voltage is applied to the pixel electrode 18, the common electrode 42 has a (+) potential, and the white particles 64 having a (+) charge are transferred to the first substrate 20. When the light is input from the outside, the input light is hardly reflected, thereby realizing black.

A manufacturing method of the conventional electrophoretic display device 1 having the above structure is schematically described as follows.

2 is a flowchart schematically showing a method of manufacturing a conventional electrophoretic display device 1.

As shown in FIG. 2, first, a plurality of gate lines and data lines defining pixel regions are formed on a first substrate 20, and the gate lines and data are formed in each of the pixel regions. A thin film transistor which is a driving element connected to the line is formed (S101). Subsequently, the pixel electrode 18 is formed on the first substrate 20 on which the thin film transistor is formed (S102).

Meanwhile, the common electrode 42 is formed on the second substrate 40 (S103). Subsequently, a partition wall is formed on the second substrate 40 to partition each pixel area, and then an electrophoretic material is filled in the pixel area partitioned by the partition wall to form an electrophoretic layer 60 (S105). Thereafter, the common electrode 42 is formed on the second substrate 40 on which the electrophoretic layer 60 is formed, and a protective film is attached thereon (S105 and S106). At this time, although not shown in the figure, an adhesive layer is formed on the common electrode 42 so that the protective film is attached to the adhesive layer. In order to prevent the adhesion of the adhesive layer from deteriorating or the adhesion of the foreign matter to the adhesive layer when the second substrate 40 is transferred to the bonding process in order to bond the second substrate 40 to the first substrate 20. To be attached.

Typically, an electrophoretic display device manufacturer receives a second substrate 40 on which an electrophoretic layer 60 is formed, and attaches the second substrate 40 to the first substrate 20. That is, the second substrate 40 having the electrophoretic layer 60 formed thereon is transferred from the outside to the electrophoretic display element forming line, and then the first substrate 20 and the second substrate 40 are bonded to each other to form the electrophoretic display element. To complete.

Therefore, since the second substrate 40 on which the electrophoretic layer 60 is formed has to be transported a long distance by a conveying means such as a vehicle, the adhesive force of the adhesive layer decreases during the conveying process, so that the first substrate 20 and the second substrate ( When bonding the 40) may cause a defect, the protective film is to prevent the defect by preventing the adhesive force of the adhesive layer is weakened.

The second substrate 40 transferred to the manufacturing line of the electrophoretic display device manufacturer is peeled off the protective film is attached, and then aligned with the first substrate 20 to be bonded to complete the electrophoretic display device (S109).

However, the following problem occurs in the conventional electrophoretic display device 1 manufactured by the above method.

In the conventional electrophoretic display device 1, the first substrate 20 and the second substrate 40 are separately manufactured, and then the first and second substrates 20 and 40 are bonded to each other by an adhesive layer. .

However, since the unit pixels of the electrophoretic display element are formed to have a small size of less than 150 μm in width and length, it is very difficult to align the electrophoretic layer with the pixels so as to exactly fit this size. If the first substrate on which the electrophoretic layer and the thin film transistor are formed is not aligned correctly, the electric field may not be correctly transferred to the electrophoretic particles, which may cause a driving error.

In addition, since the first substrate 20 and the second substrate 40 are each manufactured in different processes, they are transported by a conveying means and then bonded to each other in the bonding process, so that the manufacturing process cannot be formed inline. The manufacturing process is delayed and the manufacturing cost increases.

Meanwhile, the common electrode 42 is formed on the second substrate 40, the electrophoretic layer 60 is applied, and an adhesive layer is applied. Then, the second substrate 40 is transferred to a bonding process to transfer the first substrate 20. ) In order to prevent the adhesion of the adhesive layer from deteriorating or adhered to the adhesive layer, the adhesive film must be transported with the protective film attached to the adhesive layer, and the second substrate 40 transferred at the same time is transferred to the first substrate. In order to attach to the 20, the protective film must be peeled from the second substrate 40. Static electricity is generated during the peeling of the protective film, and the generated static electricity causes misalignment in the initial arrangement of the electrophoretic particles. During operation of the electrophoretic display element, a moire in the shape of a comb-pattern was caused.

As described above, in the conventional electrophoretic display device, since the first substrate 20 and the second substrate 40 are manufactured in different processes, the first substrate 20 and the second substrate 40 when the electrophoretic layer is bonded. There is a problem that misalignment occurs or the process becomes complicated, and static electricity is generated when the adhesive layer is peeled off, resulting in poor image quality.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to provide an electrophoretic display device manufacturing method which can reduce manufacturing cost and simplify the manufacturing process by directly forming an electrophoretic layer on a substrate on which a thin film transistor is formed. do.

It is another object of the present invention to provide a method for manufacturing an electrophoretic display device capable of preventing the deterioration of image quality due to the aggregation of electrophoretic particles.

In order to achieve the above object, an electrophoretic display device manufacturing method according to the present invention comprises the steps of providing a first substrate and a second substrate comprising an image display unit and a non-display unit including a plurality of pixels; Forming a thin film transistor on the first substrate; Forming a protective layer on the first substrate; Forming a partition on the non-image display unit on the passivation layer and forming a pixel electrode on the image display unit; Forming an electrophoretic layer by applying an electrophoretic material using a screen mask to an image display unit between partition walls; Forming a common electrode on the second substrate; And bonding the first substrate and the second substrate to each other.

The screen mask is a metal mask or mesh mask, in which case about 50-400 meshes are formed per inch.

In the present invention, since the electrophoretic layer is directly formed on the array substrate on which the thin film transistor is formed, the electrophoretic layer can be used to bond the electrophoretic layer to the array substrate. have. In addition, since the electrophoretic layer may be formed inline on the manufacturing line of the array substrate forming the thin film transistor, the manufacturing process may be simplified.

In addition, since the present invention does not use a protective film for protecting the electrophoretic layer, it is possible to improve the problem of deterioration in image quality caused by the static electricity generated when the protective film is removed. Since the layer is directly formed, it is possible to fundamentally solve the problem of deterioration of image quality due to misalignment, compared to the prior art, in which an electrophoretic layer is separately manufactured and then bonded through an alignment process.

Further, in the present invention, since the electrophoretic layer is formed by applying the electrophoretic material on the substrate by the screen mask method, the electrophoretic particles are uniformly distributed in the electrophoretic layer and the surface of the electrophoretic layer can be formed flat. It becomes possible.

1 is a view showing a conventional electrophoretic display device.
2 is a flow chart briefly showing a method of manufacturing a conventional electrophoretic display device.
3 is a flow chart briefly showing a method of manufacturing an electrophoretic display device according to the present invention.
4A-4G illustrate a method of manufacturing an electrophoretic display device according to the present invention.
5A-5C illustrate a method of forming an electrophoretic layer in an electrophoretic display device according to the present invention.

Hereinafter, an electrophoretic display device and a method of manufacturing the same according to the present invention will be described in detail with reference to the accompanying drawings.

3 is a flowchart schematically illustrating a manufacturing process of an electrophoretic display device according to the present invention.

As shown in FIG. 3, first, a plurality of gate lines and data lines defining pixel regions are formed on a first substrate, and thin film transistors, which are driving elements connected to the gate lines and data lines, are formed in each of the pixel regions. (S201). Subsequently, barrier ribs are formed in the image non-display portion on the first substrate on which the thin film transistor is formed, and then pixel electrodes are formed in the image display portion (S202 and S203).

The partition wall partitions pixel areas formed on the first substrate from each other. The partition wall is formed in a matrix shape on the first substrate in a vertical and horizontal direction, and the pixel electrode is formed in the pixel area partitioned by the partition wall. In this case, the pixel electrode may be formed first on the image display part of the first substrate, and then the partition wall may be formed on the image non-display part.

Meanwhile, a common electrode is formed on the second substrate (S204), and the first substrate and the second substrate are bonded to each other by applying pressure in a state in which the second substrate on which the common electrode is formed is aligned with the first substrate (S205, S206).

Thereafter, an electrophoretic material is formed by injecting an electrophoretic material through the injection holes formed in the bonded first and second substrates (S207), and the injection hole is sealed to complete the electrophoretic display device (S208).

In the method of manufacturing an electrophoretic display device according to the present invention as described above, various electrodes such as thin film transistors are formed on a first substrate and a common electrode is formed on a second substrate, and the thin film transistors and the second substrate formed on the first substrate are formed. The common electrode to be formed is formed by the same manufacturing process. In other words, in the present invention, since the process of the first substrate and the process of the second substrate can be performed in the same manufacturing line, the first substrate and the first substrate and the first substrate are fabricated after the second substrate is manufactured in another factory in a conventional electrophoretic display device. Compared to the bonding of the two substrates, the first substrate and the second substrate can be manufactured inline, and the first substrate and the second substrate can be bonded together.

As described above, in the present invention, since the manufacturing process of the first substrate and the second substrate is performed inline, the adhesive layer or the adhesive layer for attaching the substrate on which the transfer of the second substrate or the electrophoretic layer is formed to the thin film transistor substrate is protected. To avoid the need for a protective film, the process of peeling off the protective film for protecting the adhesive layer of the substrate on which the electrophoretic layer is formed, and the like, it is possible to simplify the manufacturing process.

Hereinafter, a method of manufacturing an electrophoretic display device according to the present invention will be described in detail with reference to FIGS. 4A to 4G. In this case, although the electrophoretic display device is substantially composed of a plurality of unit pixels, only one pixel is shown in the drawing for convenience of description.

First, as shown in FIG. 4A, a Cr, Mo, Ta, Cu, Ti, Al, or Al alloy is formed on a first substrate 120 including an image display unit and an image non-display unit and made of a transparent material such as glass or plastic. After stacking an opaque metal having good conductivity by a sputtering process and etching by a photolithography process to form a gate electrode 111, the substrate 120 having the gate electrode 111 formed thereon. The gate insulating layer 122 is formed by stacking an inorganic insulating material such as SiO ₂ or SiNx by CVD (Chemicla Vapor Deposition).

Subsequently, as illustrated in FIG. 4B, a semiconductor material such as amorphous silicon (a-Si) is deposited on the entire first substrate 120 by CVD and then etched to form a semiconductor layer 113. In addition, although not shown in the drawing, an ohmic contact that ohmic-contacts the source electrode and the drain electrode to be subsequently formed with a semiconductor layer 113 by doping impurities or stacking amorphous silicon added with impurities to a part of the semiconductor layer 113. To form an ohmic contact layer.

Thereafter, as illustrated in FIG. 4C, an opaque metal having good conductivity such as Cr, Mo, Ta, Cu, Ti, Al, or Al alloy is laminated on the first substrate 120 by sputtering and then etched to form a semiconductor. On the layer 113, strictly speaking, the source electrode 115 and the drain electrode 116 are formed on the ohmic contact layer, and then the entire first substrate 120 having the source electrode 115 and the drain electrode 116 formed thereon. A protective layer 124 is formed by stacking an organic insulating material such as BCB (Benzo Cyclo Butene) or photo acryl. In this case, a part of the protective layer 124 is etched to form a contact hole 117 through which the drain electrode 116 is exposed to the outside.

In addition, although not shown, the protective layer 124 may be formed of a plurality of layers. For example, the protective layer 124 may be formed of a double layer of an organic insulating layer made of an organic insulating material such as BCB or photoacryl and an inorganic insulating layer made of an inorganic insulating material such as SiO ₂ or SiNx. It may be formed of an insulating layer, an organic insulating layer and an inorganic insulating layer. As the organic insulating layer is formed, the surface of the protective layer 124 is formed to be flat, and the interface characteristic with the protective layer 124 is improved by applying the inorganic insulating layer.

Subsequently, as illustrated in FIG. 4D, the partition wall 180 is formed on the image non-display portion of the first substrate 120. The partition wall 180 may be formed by laminating an insulating layer made of a resin, or the like by etching using a photolithography method using a photoresist, or may be formed by laminating a photosensitive resin and then etching by a photolithography method. In addition, the partition wall 180 may be formed by printing the partition wall 180 patterned by a printing method such as a printing roll, and after manufacturing a mold having grooves corresponding to the partition wall, the insulating material of the mold is formed. It can also be formed by transferring to the substrate 120. In addition, the partition 180 may be formed by an imprint method.

In practice, the formation of the partition wall 180 is not limited by a specific method. The specific method described above is for convenience of description and is not intended to limit the present invention. The partition 180 may be formed by various known methods.

Subsequently, as shown in FIG. 4E, a transparent conductive material, such as indium tin oxide (ITO) or indium zinc oxide (IZO), metals such as Mo and AlNd, are formed over the entire first substrate 120 on which the partition wall 180 is formed. Stacked and etched to form a pixel electrode 118 electrically connected to the drain electrode 116 of the thin film transistor through the contact hole 117 in the image display portion of the first substrate 120.

In this case, the metal layer is formed on the passivation layer 124 and etched to form the pixel electrode 118 in the image display portion of the first substrate 120 first, and then the barrier 180 in the image non-display portion of the first substrate 120. May be formed.

Subsequently, as illustrated in FIG. 4F, an electrophoretic material is dropped into the pixel partitioned by the partition wall 180 to form the electrophoretic layer 160.

Thereafter, as shown in FIG. 4G, the electrophoretic layer 160 is sealed by a sealing layer 168 made of a thermosetting resin or an ultraviolet curable resin, and then the second substrate 140 made of a transparent material such as glass or plastic. ), A common electrode 142 is formed by stacking a transparent conductive material such as ITO or IZO, and an adhesive is applied to the top surface of the barrier 180 of the first substrate 120, followed by the first substrate 120 and the second substrate. The first substrate 120 and the second substrate 140 are bonded to each other by applying pressure in the state in which the 140 is aligned. In this case, the adhesive may be applied to the second substrate 140.

As described above, in the present invention, the electrophoretic layer is directly formed on the first substrate 120 to protect the adhesive layer or the adhesive layer for bonding the electrophoretic layer compared to the conventional electrophoretic layer formed on a separate substrate. Since the film is not required, the manufacturing cost can be reduced, and the electrophoretic layer can be formed in-line on the existing thin film transistor manufacturing line, thereby simplifying the manufacturing process. The detailed description is as follows.

The electrophoretic layer forming method used in the present invention is a forming method by the screen printing method. The screen printing forming method has an advantage over a method of dispensing electrophoretic material between the partition walls 180 of the first substrate 120. That is, when the electrophoretic material is dropped on the first substrate 120 by the dropping method, the particles contained in the electrophoretic material are dropped by a predetermined amount instead of being injected into the pixels between the partitions 180 at once. Are locally gathered or agglomerated with each other, resulting in an uneven distribution of electrophoretic particles throughout the electrophoretic layer. The non-uniform distribution of these electrophoretic particles varies depending on the position of the reflected light. This can cause spots to appear on the screen upon completion.

In addition, when the electrophoretic material is dropped by the dropping method, the electrophoretic material dropped at a relatively high position is flowed when dropped onto the first substrate 120 by the high potential energy, the electrophoretic material is In general, since the viscosity of about 1-10cp the electrophoretic material is dropped to form an electrophoretic layer, the surface of the electrophoretic layer is not flat due to the flow of the electrophoretic material.

In the present invention, since the electrophoretic material is injected into the pixels between the partition walls 180 by the screen printing method, the electrophoretic particles are uniformly distributed throughout the electrophoretic layer, and the surface of the electrophoretic layer is not flat. To solve the problem.

5A-5C illustrate a method of forming an electrophoretic layer of an electrophoretic display device according to the present invention. In this case, only the first substrate 120, the partition wall 180, and the pixel electrode 118 are illustrated for the convenience of description and the configuration of the thin film transistor is omitted.

As shown in FIG. 5A, first, a barrier rib 180 is formed in an image non-display area, and a first substrate 120 having pixel electrodes 118 is formed in an image display area, and then, as shown in FIG. 5B. The screen mask 190 is positioned on the first substrate 120. In this case, the screen mask 190 uses a metal mask or a mesh (mesh) mask.

Then, as shown in Figure 5c, after applying the electrophoretic material 162 on the screen mask 190, by applying a pressure from one side of the screen mask 190 to the other side by the bar 192 The electrophoretic material 162 is injected into the region between the partition walls 180.

In the present invention, the electrophoretic material 162 including the color particles is mainly injected with the electrophoretic material using a metal mask, and the electrophoretic material 162 with the black and white particles is injected with the mesh mask. This is because a plurality of meshes are formed in the mesh mask in the openings of the mask from which the electrophoretic material 162 is discharged, and thus interfere with the electrophoretic material 162. That is, since the electrophoretic material 162 discharged through the opening collides with the mesh formed in the opening, the electrophoretic material 162 is injected not only into a desired pixel but also by invading adjacent pixels. In the case of a black and white electrophoretic material, an electrophoretic material containing the same black and white particles is injected into adjacent pixels so that there is no problem even when the electrophoretic material of the corresponding pixel is injected into an adjacent pixel. In the case of electrophoretic materials, electrophoretic materials of different colors are injected into adjacent pixels. Therefore, when electrophoretic materials of a specific color are injected into adjacent pixels due to the interference of the mesh, defects may be caused to be mixed with electrophoretic materials of different colors. Will occur. Therefore, the mesh mask is more suitable for injecting black and white electrophoretic material.

However, in the present invention, the metal mask and the mesh mask are not only used to inject the color electrophoretic material and the black and white electrophoretic material, respectively. Both metal and mesh masks can be used to inject color and black and white electrophoretic materials.

In particular, according to the present invention, it is possible to prevent the electrophoretic particles from being uniformly distributed or the surface of the electrophoretic layer not to be flat by using a mesh mask. The mesh mask is formed 50-400 mesh per inch, this mesh is formed with a spacing between the mesh (ie mesh opening) of about 25-115㎛ when the line width of the mesh is about 25-115㎛. Thus, when the electrophoretic material is discharged, the number of electrophoretic particles discharged through one mesh opening is limited. In other words, because each electrophoretic particle is discharged through each mesh opening, not only the electrophoretic particles discharged are agglomerated, but also the electrophoretic particles already agglomerated when applied onto the mesh mask are discharged through the mesh opening and then agglomerated. Since the electrophoretic particles are separated, the separated electrophoretic particles are injected when injected between the partition walls 180.

In other words, when the mesh mask is used, the electrophoretic particles distributed in the electrophoretic layer can be uniformly distributed.

In addition, when the electrophoretic material is discharged using a mesh mask, since the electrophoretic material is separated and discharged for each area through a plurality of meshes, the flow generated in the injected electrophoretic material can be minimized, and thus, the electrophoretic layer The surface of the can be as flat as possible.

As described above, in the present invention, since the electrophoretic layer is directly applied to the substrate on which the thin film transistor is formed, the electrophoretic layer protects the adhesive layer or the adhesive layer for bonding the electrophoretic layer compared with the conventional electrophoretic layer formed on a separate substrate. In addition to reducing the manufacturing cost by eliminating the need for a protective film, the electrophoretic layer can be formed on an existing thin film transistor manufacturing line or a common electrode forming line, thereby simplifying the manufacturing process.

In addition, in the present invention, since the electrophoretic material is injected onto the substrate by screen printing to form an electrophoretic layer, the electrophoretic particles may be uniformly distributed on the electrophoretic layer and the surface of the electrophoretic layer may be formed flat. Will be.

120,140 substrate 111 gate electrode
113: semiconductor layer 115: source electrode
116: drain electrode 118: pixel electrode
124: protective layer 142: common electrode
160: electrophoretic layer 168: sealing layer
180: bulkhead 190: screen mask

Claims

Providing a first substrate and a second substrate including an image display unit including a plurality of pixels and an image non-display unit;
Forming a thin film transistor on the first substrate;
Forming a protective layer on the first substrate;
Forming a partition on the non-image display unit on the passivation layer and forming a pixel electrode on the image display unit;
Forming an electrophoretic layer by applying an electrophoretic material using a screen mask to an image display unit between partition walls;
Forming a common electrode on the second substrate; And
An electrophoretic display device manufacturing method comprising the step of bonding the first substrate and the second substrate.

The method of claim 1, wherein the forming of the first barrier rib and the pixel electrode comprises:
Forming a partition on the image non-display portion on the protective layer; And
A method of manufacturing an electrophoretic display device, comprising forming a pixel electrode on an image display unit on a protective layer.

The method of claim 1, wherein the forming of the barrier ribs and the pixel electrode comprises:
Forming a pixel electrode on the image display portion on the protective layer; And
A method of manufacturing an electrophoretic display device, comprising the step of forming a partition wall on an image non-display portion on a protective layer.

The method of claim 1, wherein the screen mask is a metal mask.

The method of claim 1, wherein the screen mask is a mesh mask.

The method of claim 5, wherein the mesh mask is formed with 50-400 meshes per inch.

The method of claim 1, wherein the electrophoretic material comprises color particles having charge characteristics.

The method of claim 7, wherein the electrophoretic material further comprises a dispersion medium.

The method of claim 1, wherein the forming of the thin film transistor comprises:
Forming a gate electrode on the first substrate;
Forming a semiconductor layer on the gate electrode;
Forming a source electrode and a drain electrode on the semiconductor layer.