KR100964575B1 - Method of manufacturing display device having the flexibility and carrier plate appling thereof - Google Patents

Abstract

Disclosed are a method of manufacturing a flexible display device in which deformation does not occur, and a carrier substrate applied to support a flexible substrate in a process of forming a flexible display device. The plastic substrate is laminated on a carrier substrate having a thermal expansion coefficient corresponding to that of the plastic substrate, and a display element is formed on the surface of the plastic substrate. The carrier substrate is then separated from the plastic substrate. Therefore, the flexible substrate has a structure that effectively alleviates the change caused by the difference in thermal expansion coefficient between the plastic substrate and the carrier substrate, thereby effectively preventing warpage of the plastic substrate during the display element formation process.

Description

Manufacturing method of flexible display device and carrier substrate applied thereto TECHNICAL FIELD

1 is a flowchart illustrating a method of manufacturing a flexible display device according to a first embodiment of the present invention.

2 is a process flowchart illustrating a method of manufacturing a flexible display device according to a second embodiment of the present invention.

3 is a configuration diagram illustrating a carrier substrate applied to a method of forming a flexible display device of the present invention.

4a to 4c are diagrams showing comparative experiments of a bending state of a plastic substrate according to a change in lamination temperature of the plastic substrate in the first embodiment of the present invention.

FIG. 5 is a view illustrating a comparative experiment of a warpage state of a plastic substrate according to a difference in thermal expansion coefficient between the carrier substrate and the plastic substrate in the second embodiment of the present invention.

* Description of the symbols for the main parts of the drawings *

120: plastic substrate 100, 200: carrier substrate

The present invention relates to a method for manufacturing a flexible display device and a carrier substrate applied thereto. More particularly, the present invention relates to a method for manufacturing a flexible display device in which deformation does not occur and to support a flexible substrate in a process of forming the flexible display device. It relates to a carrier substrate to be applied.

Recently, with the development of technology, the generalization of the Internet, and the explosion of the amount of information communicated, an “ubiquitous display” environment where information can be accessed at any time and anywhere is being created. Therefore, the role of the display device, which is a medium for outputting information, becomes more important, and its range of use is becoming more widespread.

In order to realize such a ubiquitous display environment, it is possible to improve the portability of the display device and to display various multimedia information, and to have a light, wide display area, high resolution, and high display speed. Should be required.

In response to these demands, research has been actively conducted in the direction of increasing the size of the display device, reducing the density of the glass substrate and the thickness of the glass substrate constituting the device. However, when the glass density of the glass substrate applied to the display device, that is, the liquid crystal display panel, is reduced, silicon dioxide (SiO ₂ ) constituting the glass substrate is substantially reduced.

The technique of lowering the glass substrate density further faces limitations because it determines all physical property values of the glass substrate.

In addition, the size of the display device should be reduced in order to solve the aforementioned problem of portability, but this has a problem that conflicts with the desire of consumers who want a large display device.

Therefore, there is a need for a flexible display device in which a display device is formed on a plastic substrate in order to simultaneously satisfy a large screen property and a light and portable property.

The above-mentioned flexible display device may ultimately be manufactured in a roll-to-roll manner. However, in order to produce a flexible display device having flexibility in the above-described manner, not only a dedicated facility for applying a plastic substrate in all processes of the production stage but also a large investment cost is required.

Currently, existing LCD manufacturers such as Sharp and Philips are researching flexible display devices, but most of them are developing flexible display devices by devising dedicated chucks to apply plastic substrates. There is a situation.

However, this study has a drawback that the current mass production equipment should be drastically changed because the existing LCD mass production equipment cannot be used as it is.

In addition, a method of applying a plastic substrate to an LCD mass production facility by attaching the plastic substrate to a glass substrate coated with an adhesive has been proposed. However, the method described above may be used to determine the coefficient of thermal expansion between the glass substrate and the plastic substrate during the process of forming a display device. Due to the difference, warpage of the plastic substrate occurs. This causes damage to the display element formed on the plastic substrate.

Accordingly, an object of the present invention for solving the above problems is to provide a method for preventing bending of a plastic substrate supported on a carrier substrate and forming a flexible display device under existing display mass production facilities.

In addition, another object of the present invention to provide a carrier substrate applied to prevent the bending of the plastic substrate applied to the flexible display device forming process and to form a flexible display device under existing display production equipment.

According to one aspect of the present invention, there is provided a method of manufacturing a flexible display device, comprising: (a) laminating the plastic substrate on a carrier substrate having a thermal expansion coefficient corresponding to that of the plastic substrate; step; (b) forming a display element on the surface of the plastic substrate; And (c) separating the carrier substrate from the plastic substrate.

In addition, a method of manufacturing a flexible display device according to another aspect for realizing the object of the present invention, after laminating a plastic substrate on a carrier substrate flexible to form an image display element of the display device on the surface of the plastic substrate In the method of manufacturing a display device, (a) laminating the plastic substrate on the carrier substrate at an average temperature between a first temperature before the display element forming process is performed and a second temperature at which the display element forming process is performed. step; (b) forming a display device on a surface of the plastic substrate stacked on the carrier substrate; And (c) separating the carrier substrate from the plastic substrate.

In addition, the carrier substrate for achieving the other object of the present invention, the plastic substrate on which the image display element is formed, but is formed of a material having a thermal expansion coefficient corresponding to the thermal expansion coefficient of the plastic substrate.

The carrier substrate has a structure that effectively alleviates the change caused by the difference in thermal expansion coefficient between the plastic substrate, which is a flexible substrate, and the carrier substrate, thereby effectively preventing warpage of the plastic substrate during the display element formation process.

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

1 is a process flowchart illustrating a method of manufacturing a flexible display device according to a first embodiment of the present invention.

Referring to FIG. 1, a bonding material is coated on a carrier substrate to have a uniform thickness, and then a plastic substrate is laminated on the carrier substrate under a predetermined temperature (steps S110 and S120).

Here, the carrier substrate is a silicon substrate or a glass substrate, and a predetermined temperature applied when the plastic substrate is laminated (laminated) on the glass substrate, which is a carrier substrate, is then applied before forming the image display element of the flexible display device. An average temperature expressed by arithmetic average of the first process temperature and the second process temperature applied to the process of forming the image display element.

That is, when the plastic substrate is laminated on the glass substrate at an average temperature between room temperature and the process temperature for forming the image display device, prevention and stress of bending of the plastic substrate due to a mismatch between thermal expansion coefficients of the glass substrate and the plastic substrate Occurrence can be minimized.

Subsequently, the plastic substrate is formed as a color filter substrate by performing a process of forming an image display element of a display device on a plastic substrate attached to the glass substrate (a pixel layer forming process) (step S130).

The process of forming the display device includes forming a color filter, which is a process of forming a black matrix, a color filter, an overcoating layer, and a common electrode on a plastic substrate.

Specifically, a method of forming a color filter substrate may be defined. The plastic substrate may be defined as the light transmitting region where the image is displayed and the light blocking region that blocks the light, and then the black photoresist may be slit coated or spin coated. ) Apply the process.

Here, the black photoresist includes a positive photoresist in which the exposed part is removed by development, or a negative photoresist in which the exposed part remains.

Subsequently, the coated black photoresist is exposed to ultraviolet (Ultraviolet) using a mask (not shown). At this time, the molecular bonds of the black photoresist in the portion irradiated with ultraviolet rays are broken, thereby decreasing the molecular weight of the black photoresist in the light transmitting region. The black photoresist in the light blocking region, which is a portion through which the ultraviolet rays are not transmitted, maintains a polymer state.

The black photoresist is then developed. The black photoresist having the reduced molecular weight by the above phenomenon is removed to form a black matrix existing only in the light shielding region.

Subsequently, a color filter is formed on the upper substrate on which the black matrix is formed. The color filter selectively transmits only light of a specific wavelength. Preferably, the color filter is formed by applying a photoresist comprising a pigment onto a plastic substrate and then exposing and developing the photoresist. In this case, the black matrix may be formed after the color filter is first formed.

Subsequently, a transparent organic material is coated on the plastic substrate on which the color filter is formed to form the overcoating layer. The overcoating layer is used to remove the step caused by the black matrix and the color filter.

Next, by applying a transparent conductive material to the entire surface of the overcoating layer and then removing a portion of the transparent conductive material corresponding to the light shielding region, thereby forming a common electrode disposed in the light transmitting region (pixel region) on the color filter, The color filter substrate is formed.

Subsequently, by separating the carrier substrate from the color filter substrate formed by forming the display element on the plastic substrate, a color filter substrate having flexibility, which is a flexible display device, is formed (step S140). The adhesive applied to bring the substrate and the plastic substrate into close contact with each other is melted with an organic solvent, eluted, and removed.

2 is a process flowchart illustrating a method of manufacturing a flexible display device according to a second embodiment of the present invention.

Referring to FIG. 2, first, an adhesive material (Bonding Matter) is applied on a carrier substrate with a uniform thickness, and then a plastic substrate is laminated on a carrier substrate having a thermal expansion coefficient corresponding to that of the plastic (step S210).

Here, the carrier substrate is a substrate formed of a high heat-resistant engineering plastic, a polymer containing a nanocomposite compound, a reinforced fiber plastic, the engineering plastic is a polyamide resin, polyoxymethylene resin, polycarbonate resin, polyphenylene oxide resin, poly Ester resins, polyester ketone resins, and the like.

That is, when the process of forming the display device after laminating the plastic substrate on a carrier substrate having a thermal expansion coefficient similar to that of the plastic substrate, the bending of the plastic substrate due to the mismatch of the thermal expansion coefficient of the glass substrate and the plastic substrate is not observed. In addition, it is possible to prevent the occurrence of stress and to minimize the occurrence of stress on the display device.

Subsequently, the plastic substrate is formed into an array substrate by performing a process of forming a display element of a display device on a surface of the plastic substrate attached to the carrier substrate (TFT wiring forming process) (step S230).                     

The process of forming the display device is an array substrate forming process of forming a thin film transistor, a gate insulating film, a passivation film, an organic film, a pixel electrode, etc., which operate as a switching device on a plastic substrate.

In detail, a method of forming the array substrate is first formed by depositing a conductive material on a lower substrate, and then etching a part of the conductive material to form a gate electrode and a gate line. Thereafter, the gate insulating film is deposited on the entire surface of the lower substrate on which the gate electrode and the gate line are formed. The gate insulating layer includes a silicon nitride layer (SiNx) as a transparent material.

Subsequently, amorphous silicon and N + amorphous silicon are deposited and etched to form a semiconductor layer on the gate insulating film corresponding to the gate electrode. Subsequently, a conductive material is deposited on the gate insulating film on which the semiconductor layer is formed. Subsequently, a portion of the conductive material is etched to form a source electrode, a source line, and a drain electrode. Thus, the thin film transistor including a source electrode, a gate electrode, a drain electrode, and a semiconductor layer is formed.

Subsequently, a passivation layer is formed by depositing a transparent insulating material on a lower substrate on which the thin film transistor is formed, and then, a portion of the passivation layer is removed to form an opening exposing a portion of the drain electrode. In this case, the opening may be formed after the organic layer is formed.

Subsequently, an organic material is coated on the passivation film to form an organic film, and then the organic film is exposed and developed to form an organic film in which a part of the drain electrode is opened. At this time, it is preferable to form a recess in the upper surface of the organic film.

Subsequently, a transparent conductive material is deposited on the organic layer and the passivation layer. The transparent conductive material includes ITO, IZO, ZO and the like. Preferably, the transparent conductive material comprises ITO.

Subsequently, a portion of the transparent conductive material is etched to form the pixel electrode in the pixel region to form an array substrate. In this case, a reflective electrode may be formed on the organic layer and the transparent electrode.

Subsequently, the carrier substrate is separated from the array substrate formed by forming the display element on the plastic substrate, thereby forming an array substrate having flexibility applied to a flexible display device (step S240).

Here, the separation of the plastic substrate is performed by dissolving and dissolving the adhesive that adheres the carrier substrate and the plastic substrate to each other with an organic solvent.

3 is a configuration diagram illustrating a carrier substrate applied to a method of forming a flexible display device of the present invention.

Referring to FIG. 3, the carrier substrate 200 is a substrate that serves to support the plastic substrate 120 to form a flexible display device, and has a square shape formed of a material having a similar thermal expansion coefficient to that of the plastic substrate. (Plate).

Here, the material having a coefficient of thermal expansion similar to that of the plastic substrate 120 may be a high heat resistant engineering plastic (polyamide resin, polyoxymethylene resin, polycabonate resin, polyphenylene oxide). Resin (Polypenleneoxide Resin), polyester (polyesther), polyester ketone resin), polymers containing nano-compounds and reinforced fiber plastics.

Therefore, the carrier substrate 200 formed of the above-described material prevents the difference in the coefficient of thermal expansion between the carrier substrate 200 and the plastic substrate 120 in advance in forming the flexible display device having the flexible characteristics. The warpage phenomenon of 120 and the stress of the image display element formed on the plastic substrate 120 can be prevented in advance.

Experimental Example 1

After stacking the plastic substrate on the glass substrate as the carrier substrate at about 25 ° C., a deposition process of forming a predetermined film quality on the plastic substrate was performed by increasing the process temperature of the deposition chamber to about 150 ° C. to form a display device.

Here, the glass substrate, which is a carrier substrate, has a thermal expansion coefficient of 5 ppm / ° C., and the plastic substrate is a substrate formed of polyethersulfone (Polyethersuifone), and has a thermal expansion coefficient of about 50 ppm / ° C., so that the temperature of the deposition chamber is 25 ° C. When the temperature is raised to 150 ° C., the glass substrate generates 0.0625% of deformation, while the plastic substrate produces 0.6250% of deformation.

Therefore, after stacking the plastic substrate on the glass substrate which is the carrier substrate at about 25 ° C., if the process temperature is increased to about 150 ° C. to form the display element, the deformation of the plastic substrate is greater, so the figure shown in FIG. As described above, the upper surface of the substrate is convexly curved.

Experimental Example 2

After performing a process of laminating a plastic substrate on the glass substrate as a carrier substrate and depositing a thin film at a temperature of 150 ° C., which is a deposition process for forming a display device, the plastic substrate was left at about 25 ° C.

Here, the glass substrate, which is a carrier substrate, has a thermal expansion coefficient of 5 ppm / ° C., and the plastic substrate is a substrate formed of polyethersulfone (Polyethersuifone), and has a thermal expansion coefficient of about 50 ppm / ° C., so that the temperature of the deposition chamber is 25 ° C. When the temperature is raised to 150 ° C., the glass substrate undergoes 0.0625% of deformation and the plastic substrate exhibits 0.6250% of deformation.

Therefore, when the plastic substrate is laminated on the glass substrate, which is the carrier substrate, at the process temperature of 150 ° C. to form the display element, and the plastic substrate is left at about 25 ° C., the deformation of the plastic substrate is greater, which is illustrated in FIG. 4B. As shown in the figure, the bottom surface of the substrate is convexly curved.

Experimental Example 3

After stacking the plastic substrate on the glass substrate as the carrier substrate at about 85 ° C., a deposition process of forming a predetermined film quality on the plastic substrate was performed by increasing the process temperature of the deposition chamber to about 150 ° C. to form a display device.

Here, the glass substrate, which is a carrier substrate, has a thermal expansion coefficient of 5 ppm / ° C., and the plastic substrate is a substrate formed of polyethersulfone (Polyethersuifone), and has a thermal expansion coefficient of about 50 ppm / ° C., so that the temperature of the deposition chamber is 25 ° C. When the temperature is raised to 150 ° C., the glass substrate undergoes 0.0625% of deformation and the plastic substrate exhibits 0.6250% of deformation.

Therefore, when the deposition process temperature for forming the display element is increased to about 150 ° C. after laminating the plastic substrate on the glass substrate which is the carrier substrate at about 85 ° C., which is an average temperature between the room temperature and the deposition process temperature, deformation of the plastic substrate may occur. Since it is reduced by about 50%, the bending shape of the plastic substrate does not occur as shown in FIG. 4C.

Experimental Example 4

After stacking the plastic substrate on the reinforced plastic substrate, which is a carrier substrate having a coefficient of thermal expansion corresponding to that of the plastic substrate at about 25 ° C., the process temperature of the deposition chamber is raised to about 150 ° C. to form a display element. The deposition process for forming a was carried out.

The reinforcement plastic substrate, which is the carrier substrate, has a coefficient of thermal expansion of about 40 ppm / 占 폚, and the substrate formed of polyethersulfone, which is a plastic substrate on which the display element is formed, has a coefficient of thermal expansion of about 50 ppm / 占 폚. Herein, when the process temperature is increased from 25 ° C. to 150 ° C., the carrier substrate reinforced plastic substrate is deformed by 0.50%, and the ordinary plastic substrate is deformed by 0.6250%.

Therefore, after stacking the plastic substrate on the reinforced plastic substrate, which is a carrier substrate at about 25 ° C., the process temperature of the deposition chamber for forming the display element is increased to about 150 ° C., the plastic substrate on which the reinforced plastic substrate and the display element are formed. Since the deformation degree (coefficient of thermal expansion) of is similar, deformation of the plastic substrate does not occur as shown in FIG. 5.

As described above, the method of forming a flexible display device is a method of laminating a plastic substrate on a carrier substrate at an average temperature of room temperature and a process temperature for forming an image display element. It is possible to prevent the bending of the plastic substrate due to the mismatch of the coefficient of thermal expansion and to minimize the occurrence of stress.

In addition, the carrier substrate applied to form the flexible display device is formed of a material that can mitigate the difference in the coefficient of thermal expansion between the plastic substrate and the carrier substrate as much as possible in the high temperature chemical vapor deposition process of forming the wiring of the display device on the plastic substrate. Therefore, the warpage phenomenon of the plastic substrate can be effectively alleviated.

In addition, the method of forming a flexible substrate can be applied to a production line of an existing display apparatus without changing equipment, and thus a flexible display apparatus can be formed without equipment investment of mass production equipment.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the present invention as defined by the following claims It can be understood that

Claims (11)

(a) laminating the plastic substrate on a carrier substrate having a thermal expansion coefficient corresponding to that of the plastic substrate; (b) forming a display element on the surface of the plastic substrate; And (c) separating the carrier substrate from the plastic substrate. The method of claim 1, wherein step (a) is performed at an average temperature between a first temperature before the process of forming the display element is performed and a second temperature at which the process of forming the display element is performed. Method of manufacturing a flexible display device. The method of claim 1, wherein the carrier substrate is formed of any one material selected from a group consisting of a high heat resistant engineering plastic, a polymer including a nanocomposite compound, and a reinforced fiber plastic. The method of claim 1, wherein the plastic substrate on which the display element is formed is an array substrate or a color filter substrate of the display apparatus. In the method of manufacturing a flexible display device to form an image display element of the display device on the surface of the plastic substrate after laminating a plastic substrate on a carrier substrate, (a) laminating the plastic substrate on the carrier substrate at an average temperature between a first temperature before the display element forming process is performed and a second temperature at which the display element forming process is performed; (b) forming a display device on a surface of the plastic substrate stacked on the carrier substrate; And (c) separating the carrier substrate from the plastic substrate. The method of claim 5, wherein the carrier substrate is a glass substrate or a silicon substrate. The method of claim 5, wherein the carrier substrate is formed of a material having a thermal expansion coefficient corresponding to that of the plastic substrate. The method of claim 7, wherein the carrier substrate is formed of any one material selected from a group consisting of a high heat resistant engineering plastic, a polymer including a nanocomposite compound, and a reinforced fiber plastic. In the carrier substrate which supports the plastic substrate in which the image display element is formed, The carrier substrate is a carrier substrate, characterized in that the substrate formed of a material having a thermal expansion coefficient corresponding to the thermal expansion coefficient of the plastic substrate. 10. The carrier substrate of claim 9, wherein the material is any one selected from the group consisting of high heat resistant engineering plastics, polymers containing nanocomposite compounds, and reinforced fiber plastics. The carrier substrate of claim 10, wherein the high heat resistant engineering plastic comprises a polyamide resin, a polyoxymethylene resin, a polycarbonate resin, a polyphenylene oxide resin, a polyester resin, and a polyester ester ketone resin.

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