KR20150069409A - Method of fabricating the flexible display device - Google Patents

Abstract

A manufacturing method of a flexible display device of the present invention is for preventing a weak spot defect by blocking a laser from being transmitted to a TFT element during laser irradiation by forming a sacrificial layer of a black matrix material between a flexible substrate and an auxiliary substrate, Providing an auxiliary substrate; Forming a sacrificial layer made of black resin on the surface of the auxiliary substrate; Forming a flexible substrate on the auxiliary substrate on which the sacrificial layer is formed; Fabricating a display panel on the flexible substrate; Irradiating a laser to burn the sacrificial layer interposed between the flexible substrate and the auxiliary substrate; And separating the flexible substrate from the auxiliary substrate.

Description

[0001] METHOD OF FABRICATING THE FLEXIBLE DISPLAY DEVICE [0002]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a flexible display device, and more particularly, to a method of manufacturing a flexible display device using an auxiliary substrate to carry and process a flexible substrate.

In recent information society, the importance of display devices as visual information delivery media is getting more emphasized, and in order to take a major position in the future, it is necessary to meet requirements such as low power consumption, thinning, light weight, and high image quality.

The display device may include a cathode ray tube (CRT), an electroluminescence (EL), a light emitting diode (LED), a vacuum fluorescent display (VFD) Light emitting devices such as organic light emitting display (OLED), field emission display (FED), plasma display panel (PDP), electrophoresis display, And can be divided into a non-light emitting type, such as a liquid crystal display (LCD), which itself can not emit light.

On the other hand, a flexible display device which is not damaged even if the display device is folded or rolled is expected to become a new technology in the display device field. At present, various obstacles exist in the implementation of flexible display devices, but thin film transistor liquid crystal display devices, organic light emitting display devices, or electrophoretic display devices will become mainstream along with technology development.

Hereinafter, the flexible display device will be described in detail with reference to the drawings.

1A and 1B are photographs showing a typical flexible display device as an example.

The flexible display device is called a desktop display device. As shown in the drawing, the flexible display device is implemented on a thin substrate such as plastic and is not damaged when folded or rolled like paper. It is one of the next generation display devices. A liquid crystal display device and an organic light emitting display device are promising.

The liquid crystal display device is an apparatus for displaying an image using the optical anisotropy of a liquid crystal. Since it has excellent visibility and average power consumption as compared with conventional CRTs, it is smaller than CRTs with the same screen size, And is spotlighted as a display device.

Since the organic light emitting display device itself emits light by itself, visibility is good even when a dark place or external light enters, and since the response speed, which is an important criterion for judging the performance of a mobile display device, is fast among existing display devices, Video can be implemented. In addition, the organic light emitting display device can be slimmed in various mobile devices such as a mobile phone because the OLED display has an ultra-thin design.

In order to realize such a flexible display device, it is necessary to secure the flexibility of the substrate, and in order to secure such a substrate flexibility, a plastic flexible substrate is used instead of the conventional glass substrate.

In order to implement the flexible display device, a flexible substrate such as a plastic substrate must be used. In order to carry and process the flexible substrate, generally, the plastic substrate is attached to a glass substrate using an adhesive, The adhesive process is complicated and a lot of lamination processes are carried out, which leads to the problem that the occurrence of defects and the productivity are lowered.

That is, in order to adhere the plastic substrate to the glass substrate, a complicated adhesive process such as removal of the lower release sheet of the adhesive, lamination of the adhesive, removal of the upper release sheet of the adhesive, and lamination process of the plastic substrate must be performed, and during the lamination process, And the like. Particularly, there is a problem that the productivity is lowered due to the progress of the complicated adhesion process as described above.

In addition, when the plastic substrate bonded to the glass substrate is transported in a cemented state and the display panel is manufactured through various processes, the glass substrate is separated from the plastic substrate as the display panel.

At this time, in order to separate the plastic substrate from the adhesive attached to the glass substrate, various conditions must be satisfied in accordance with the separation process, and the adhesive is attached to the entire surface of the substrate, so that the separation process is difficult.

Recently, after a sacrificial layer made of amorphous silicon is interposed between a plastic substrate and a glass substrate, processes are performed to form a display panel and a glass substrate is separated from the plastic substrate by applying laser release .

FIGS. 2A and 2B are cross-sectional views schematically showing a process for attaching and detaching an auxiliary substrate using a laser in a general method of manufacturing a flexible display device.

2A, a buffer layer 30 made of a silicon nitride film is formed on the surface of the auxiliary substrate 50. Then, as shown in FIG.

A sacrifice layer 40 made of amorphous silicon is formed on the buffer layer 30.

The flexible substrate 10 is formed by coating a polyimide resin on the auxiliary substrate 50 on which the sacrificial layer 40 is formed.

The display panel 20 is formed on the flexible substrate 10 thus formed.

Thereafter, a laser is irradiated from the lower portion of the auxiliary substrate 50 to remove the auxiliary substrate 50 from the flexible substrate 10 on which the display panel 20 is formed, thereby forming a gap between the flexible substrate 10 and the auxiliary substrate 50 The sacrificial layer 40 is removed.

At this time, as hydrogen (H ₂ ) is generated in the sacrificial layer 40 by the laser irradiation, the flexible substrate 10 and the auxiliary substrate 50 are separated from each other, as shown in FIG. 2B.

At this time, as the sacrificial layer 40 made of amorphous silicon transmits about 43% of the irradiated laser, when the surface of the auxiliary substrate 50 made of glass is struck or scratched, The laser is concentrated in a certain region due to bending or overlapping, and when laser focusing occurs in the TFT element, a weak spot defect occurs in the pixel.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems and it is an object of the present invention to provide a flexible substrate and a method of manufacturing the flexible substrate, And a manufacturing method of a flexible display device that prevents occurrence of defective spot defects.

Other objects and features of the present invention will be described in the following description of the invention and the claims.

According to an aspect of the present invention, there is provided a method of manufacturing a flexible display device, including: providing an auxiliary substrate; Forming a sacrificial layer made of black resin on the surface of the auxiliary substrate; Forming a flexible substrate on the auxiliary substrate on which the sacrificial layer is formed; Fabricating a display panel on the flexible substrate; Irradiating a laser to burn the sacrificial layer interposed between the flexible substrate and the auxiliary substrate; And separating the flexible substrate from the auxiliary substrate.

At this time, the auxiliary substrate may be a glass substrate or a metal substrate.

The black resin may include carbon black constituting a black matrix.

The sacrificial layer may be formed to a thickness of 1 탆 to 5 탆, preferably 2 탆.

The laser can be irradiated with a power of 1 W to 3 W, preferably 1.95 W.

The laser can be scanned at a speed of 300 mm / s through a scanning method.

As described above, in the method for manufacturing a flexible display device according to the present invention, a sacrificial layer is formed of a black matrix material between a flexible substrate and an auxiliary substrate, thereby preventing transmission of laser to the TFT element during laser irradiation, Provides a possible effect.

1A and 1B are photographs showing a typical flexible display device as an example.
FIG. 2A and FIG. 2B are cross-sectional views schematically showing a process of attaching and detaching an auxiliary substrate using a laser in a general flexible display device manufacturing method. FIG.
3 is a flowchart sequentially showing a manufacturing method of a flexible display device according to an embodiment of the present invention.
4A to 4E are perspective views sequentially showing a manufacturing method of a flexible display device according to an embodiment of the present invention.
5A and 5B are diagrams showing examples of laser transmittance according to laser irradiation.
6 is a cross-sectional view illustrating a structure of a flexible display device according to an embodiment of the present invention.
FIGS. 7A and 7B are cross-sectional views schematically showing a process of removing and attaching an auxiliary substrate in the method of manufacturing the flexible display device according to the embodiment of the present invention shown in FIG. 3; FIG.

Hereinafter, preferred embodiments of a method of manufacturing a flexible display device according to the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily carry out the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS The advantages and features of the present invention and the manner of achieving them will become apparent with reference to the embodiments described in detail below with reference to the accompanying drawings. It should be understood, however, that the invention is not limited to the disclosed embodiments, but is capable of many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, To fully disclose the scope of the invention to those skilled in the art, and the invention is only defined by the scope of the claims. Like reference numerals refer to like elements throughout the specification. The dimensions and relative sizes of the layers and regions in the figures may be exaggerated for clarity of illustration.

It will be understood that when an element or layer is referred to as being another element or "on" or "on ", it includes both intervening layers or other elements in the middle, do. On the other hand, when a device is referred to as "directly on" or "directly above ", it does not intervene another device or layer in the middle.

The terms spatially relative, "below," "lower," "above," "upper," and the like, And may be used to easily describe the correlation with other elements or components. Spatially relative terms should be understood to include, in addition to the orientation shown in the drawings, terms that include different orientations of the device during use or operation. For example, when inverting an element shown in the figures, an element described as "below" or "beneath" of another element may be placed "above" another element. Thus, the exemplary term "below" can include both downward and upward directions.

The terminology used herein is for the purpose of describing embodiments only and is not intended to be limiting of the invention. In the present specification, the singular form includes plural forms unless otherwise specified in the specification. &Quot; comprise "and / or" comprising ", as used in the specification, means that the presence of stated elements, Or additions.

3 is a flowchart sequentially showing a manufacturing method of a flexible display device according to an embodiment of the present invention.

4A to 4E are perspective views sequentially showing a manufacturing method of a flexible display device according to an embodiment of the present invention.

4A, in order to manufacture a flexible display device according to an embodiment of the present invention, an auxiliary substrate 150 is first provided (S110).

Here, the auxiliary substrate 150 may support a flexible substrate during a display panel process, which will be described later. At this time, the auxiliary substrate 150 may be a glass substrate or a metal substrate.

Then, as shown in FIG. 4B, a sacrificial layer 140 is formed on the surface of the auxiliary substrate 150 (S120).

At this time, a buffer layer made of a silicon nitride film may be formed before the sacrificial layer 140 is formed on the surface of the auxiliary substrate 150. The buffer layer may serve to fix a flexible substrate to be formed on the auxiliary substrate 150 during a display panel process.

The sacrificial layer 140 according to an embodiment of the present invention may be formed of a black resin such as carbon black constituting a black matrix instead of the conventional amorphous silicon, It is possible to prevent the transmission of the laser to the TFT element during the laser irradiation for the process and to prevent the defective spot due to the damage of the TFT element.

In this case, the sacrificial layer 140 may be formed to a thickness of about 1 탆 to about 5 탆, preferably about 2 탆.

5A and 5B are diagrams showing laser transmittance according to laser irradiation. For example, the laser transmittance of each layer when a laser with a wavelength of 532 nm is irradiated is shown.

FIG. 5A shows laser transmittance in the conventional case using amorphous silicon as a sacrificial layer, and FIG. 5B shows laser transmittance in the case of the present invention using carbon black as a sacrificial layer.

Referring to FIG. 5A, the transmittance of the irradiated laser decreases while transmitting through each layer, and the total transmittance is about 20%.

At this time, the transmittances of glass, silicon nitride film, amorphous silicon and polyimide constituting each layer represent about 90%, 88%, 43% and 60%, respectively.

As described above, the conventional sacrificial layer made of amorphous silicon permeates about 20% of the irradiated laser. Therefore, when there is scratch or scratch on the surface of the auxiliary substrate made of glass, the irradiated laser bends or overlaps The laser is concentrated. At this time, when laser focusing phenomenon occurs in the TFT element, a weak light spot which causes a slight light to the pixel is caused.

On the other hand, referring to FIG. 5B, the irradiated laser has a total transmittance of about 0% due to carbon black having a transmittance of about 0%.

Accordingly, when a black resin such as carbon black is applied to the sacrificial layer as in the present invention, the transmission of the laser to the TFT element is prevented, so that even when surface damage, that is, surface scratches or scratches, weak spot defects do not occur.

Next, as shown in FIG. 4C, the flexible substrate 110 is formed on the auxiliary substrate 150 on which the sacrificial layer 140 is formed (S130).

Here, the flexible substrate 110 may be formed by coating a polyimide resin on the sacrificial layer 140. However, the present invention is not limited thereto, and the flexible substrate 110 may be attached to an upper portion of the auxiliary substrate 150 on which the sacrificial layer 140 is formed.

Then, as shown in FIG. 4D, a predetermined process is performed on the flexible substrate 110 to form a display panel 120 (S140).

Here, the display panel 120 may be any one of a liquid crystal display, an organic light emitting display, and an electrophoretic display.

FIG. 6 is a cross-sectional view exemplarily showing a structure of a flexible display device according to an embodiment of the present invention, and shows an organic light emitting display device as a display panel, for example.

6, an anode 112 made of a transparent oxide is formed on a substrate 111 made of plastic, and the anode 112 is formed on the substrate 111. In this case, A hole transport layer 113, an emission layer 114, an electron transport layer 115, an electron injection layer 116, and a cathode 117 sequentially, Are stacked.

When a polyimide (PI) material is used as the substrate 111, a back film made of polyethylene terephthalate (PET) or a stainless steel metal is formed on the back surface of the substrate 111, ) May be attached.

Based on the above structure, the organic electroluminescence device has a structure in which the holes injected from the anode 112 and the electrons injected from the cathode 117 are coupled to each other in the light emitting layer 114 via the transport layers 113 and 115 for transport, The light of the wavelength corresponding to the energy difference in the light emitting layer 114 is generated while moving to the energy level.

At this time, the light emitting layer 114 may more specifically include a red light emitting layer 114a, a green light emitting layer 114b, and a blue light emitting layer 114c for light emission of white light.

In contrast, when the display panel 120 is formed of a liquid crystal display device, the display panel 120 may include two substrates and a liquid crystal layer formed therebetween.

At this time, a thin film transistor array is formed on the lower substrate. The thin film transistor array includes a plurality of data lines to which R, G, and B data voltages are supplied, a plurality of gate lines to which gate pulses are supplied to cross the data lines, A plurality of pixel electrodes for charging a data voltage to the liquid crystal cells, and a storage capacitor connected to the pixel electrode to maintain the voltage of the liquid crystal cell. A color filter array is formed on the upper substrate, and the color filter array includes a black matrix, a color filter, and the like.

Next, as shown in FIG. 4E, the auxiliary substrate 150 is separated from the flexible substrate 110 on which the display panel 120 is formed by irradiating a laser, which will be described in detail with reference to FIGS. 7A and 7B .

FIGS. 7A and 7B are cross-sectional views schematically showing a process of removing and attaching an auxiliary substrate in the method of manufacturing the flexible display device according to the embodiment of the present invention shown in FIG.

Specifically, as shown in FIG. 7A, a laser is irradiated from a lower portion of the auxiliary substrate 150 on which the display panel 120 is formed to burn the sacrificial layer 140 (S150).

4E, the flexible substrate 110 on which the display panel 120 is formed is flipped upside down so that the auxiliary substrate 150 is loaded on the table 160 with the auxiliary substrate 150 facing upward, the laser may be irradiated from the top after loading.

7B, the flexible substrate 110 on which the display panel 120 is formed is separated from the auxiliary substrate 150 in a state where the sacrifice layer 140 is burned by laser irradiation S160).

In this case, the laser may be irradiated at a power of about 1 W to 3 W, preferably about 1.95 W, and at a speed of about 300 mm / s through a scanning method.

When the black resin such as carbon black is applied to the sacrificial layer 140 as described above, it is possible to separate the auxiliary substrate 150 and the flexible substrate 110 by burning by laser irradiation. In the sacrificial layer 140, A gap is formed between the buffer layer 130 and the sacrificial layer 140 and between the flexible substrate 110 and the sacrificial layer 140 to separate the auxiliary substrate 150 and the flexible substrate 110 .

While a great many are described in the foregoing description, it should be construed as an example of preferred embodiments rather than limiting the scope of the invention. Therefore, the invention should not be construed as limited to the embodiments described, but should be determined by equivalents to the appended claims and the claims.

110: flexible substrate 120: display panel
130: buffer layer 140: sacrificial layer
150: auxiliary substrate

Claims (8)

Providing an auxiliary substrate;
Forming a sacrificial layer made of black resin on the surface of the auxiliary substrate;
Forming a flexible substrate on the auxiliary substrate on which the sacrificial layer is formed;
Fabricating a display panel on the flexible substrate;
Irradiating a laser to burn the sacrificial layer interposed between the flexible substrate and the auxiliary substrate; And
And separating the flexible substrate from the auxiliary substrate. The manufacturing method of a flexible display device according to claim 1, wherein the auxiliary substrate is a glass substrate or a metal substrate. The manufacturing method of a flexible display device according to claim 1, wherein the black resin comprises carbon black constituting a black matrix. The manufacturing method of a flexible display device according to claim 1, wherein the sacrificial layer is formed to a thickness of 1 탆 to 5 탆. The manufacturing method of a flexible display device according to claim 4, wherein the sacrificial layer is formed to a thickness of 2 탆. The manufacturing method of a flexible display device according to claim 1, wherein the laser is irradiated with a power of 1 W to 3 W. The manufacturing method of a flexible display device according to claim 6, wherein the laser is irradiated with a power of 1.95 W. The manufacturing method of a flexible display device according to claim 1, wherein the laser is irradiated at a speed of 300 mm / s through a scanning method.

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