KR102513210B1 - Flexible display device, and method for fabricating the same - Google Patents

Abstract

The present invention provides a flexible display device capable of improving poor image quality of a display panel and a manufacturing method thereof. A flexible display device according to the present invention includes a first base film and a second base film covering an upper surface of the first base film, the first base film is hydrophobic, and the second base film is It has hydrophilic properties.

Description

Flexible display device and manufacturing method thereof

Embodiments of the present invention relate to a flexible display device and a manufacturing method thereof.

As the era develops into an information society, the importance of a flat panel display device (FPD) having excellent characteristics such as thinning, light weight, and low power consumption is increasing. Flat panel displays include Liquid Crystal Display Device (LCD), Plasma Display Panel Device (PDP), and Organic Light Emitting Display Device (OLED). An electrophoretic display device (EPD) is also widely used.

Among them, liquid crystal display devices and organic light emitting display devices including thin film transistors are excellent in resolution, color display, image quality, etc., and are widely commercialized as display devices for televisions, notebook computers, tablet computers, or desktop computers. Such liquid crystal display devices and organic light emitting display devices are also being developed as flexible display devices having flexibility.

A conventional flexible display panel includes a base film, a buffer layer, a thin film transistor, and an organic light emitting diode. The base film is provided on the auxiliary substrate and may be a flexible plastic film. A buffer layer is provided on the base film, and a thin film transistor is provided on the buffer layer. The organic light emitting diode is provided on the thin film transistor and electrically connected to the thin film transistor. Such a conventional flexible display panel may be manufactured by sequentially forming a base film, a buffer layer, a thin film transistor, and an organic light emitting diode on an auxiliary substrate, and then separating the base film and the auxiliary substrate using a laser. In this case, the base film may be provided by coating and curing a polymer material on the auxiliary substrate.

However, since the process time for curing the polymer material applied on the auxiliary substrate is long, particles may penetrate into the polymer material. In this case, a quality defect may occur in the flexible display panel due to the foreign matter.

The present invention provides a flexible display device capable of improving poor image quality of a display panel and a manufacturing method thereof.

A flexible display device according to an embodiment of the present invention includes a first base film and a second base film covering an upper surface of the first base film, wherein the first base film is hydrophobic, and the second base film The base film has hydrophilic properties.

A method of manufacturing a flexible display device according to an exemplary embodiment of the present invention includes applying a first base material on an auxiliary substrate and applying a second base material to cover upper and side surfaces of the first base material; Forming a second base film by UV curing a base material, forming a first base film by thermally curing the first base material, and separating the first base film and the second base film from the auxiliary substrate. Include steps.

An embodiment of the present invention includes a first base film and a second base film covering upper and side surfaces of the first base film. In this case, the second base film is first photocured and the first base film is thermally cured later. Therefore, in the embodiment of the present invention, since the second base film is first photocured to protect the first base film, foreign matter penetrates into the first base film, compared to the prior art having only the first base film. can prevent Accordingly, the embodiment of the present invention can improve the quality defect of the flexible display device.

Further, in an embodiment of the present invention, the first base film has hydrophobicity and the second base film has hydrophilicity, and the density of the first base film is greater than that of the second base film. Accordingly, the first base film and the second base film may be layer separated from each other to have a dual structure.

In addition to the effects of the present invention mentioned above, other features and advantages of the present invention will be described below, or will be clearly understood by those skilled in the art from such description and description.

1 is an exemplary view showing a flexible display device according to an embodiment of the present invention;
2 is a cross-sectional view showing a cross-section of one side of a flexible display device according to an exemplary embodiment of the present invention.
3 is a flowchart illustrating a method of manufacturing a flexible display device according to an exemplary embodiment of the present invention.
4A to 4F are cross-sectional views illustrating a method of manufacturing a flexible display device according to an embodiment of the present invention.

The meaning of terms described in this specification should be understood as follows.

Singular expressions should be understood to include plural expressions unless the context clearly defines otherwise, and terms such as “first” and “second” are used to distinguish one component from another, The scope of rights should not be limited by these terms. It should be understood that terms such as "comprise" or "having" do not preclude the presence or addition of one or more other features, numbers, steps, operations, components, parts, or combinations thereof. The term “at least one” should be understood to include all possible combinations from one or more related items. For example, "at least one of the first item, the second item, and the third item" means not only the first item, the second item, or the third item, respectively, but also two of the first item, the second item, and the third item. It means a combination of all items that can be presented from one or more. The term "on" means not only the case where a certain component is formed directly on top of another component, but also the case where a third component is interposed between these components.

Hereinafter, a preferred example of a flexible display device and a manufacturing method thereof according to the present invention will be described in detail with reference to the accompanying drawings. In adding reference numerals to components of each drawing, the same components may have the same numerals as much as possible even if they are displayed on different drawings. In addition, in describing the present invention, if it is determined that a detailed description of a related known configuration or function may obscure the gist of the present invention, the detailed description may be omitted.

1 is an exemplary diagram showing a flexible display device according to an exemplary embodiment of the present invention. 2 is a cross-sectional view showing a cross-section of one side of a flexible display device according to an exemplary embodiment of the present invention.

In FIG. 1 , the X-axis represents a direction parallel to the gate line, the Y-axis represents a direction parallel to the data line, and the Z-axis represents the height direction of the flexible display device. In addition, in FIG. 1, a configuration invisible by being covered by a flexible film, a circuit board, or the like is indicated by a dotted line. Hereinafter, a flexible display device according to an exemplary embodiment of the present invention will be described in detail with reference to FIGS. 1 and 2 .

Referring to FIGS. 1 and 2 , a flexible display device according to an exemplary embodiment of the present invention includes a flexible display panel 100, a gate driver 200, a source drive integrated circuit (hereinafter referred to as "IC") (310 ), a flexible film 330, a circuit board 350, and a timing controller 400.

Gate lines and data lines may be formed in the display area DA of the flexible display panel 100 , and light emitting units may be formed in intersection areas of the gate lines and data lines. The light emitting units of the display area DA may display an image.

Specifically, the flexible display panel 100 includes a base film 110, a buffer layer 130, a thin film transistor (T), a passivation layer (PAS), a planarization layer (PAC), an organic light emitting diode (OLED), and an encapsulation layer 180. ).

The base film 110 includes a first base film 111 and a second base film 113 . The first base film 111 may be a flexible plastic film. The first base film 111 may be a thermosetting polyimide film containing methacrylate. That is, the first base film 111 may be manufactured by thermally curing polyimide containing methacrylate for a long time (eg, 1 hour to 2 hours). In addition, the first base film 111 may be N,N-dimethylformamide (DMF), N,N-diethylformamide (DEF), or N-methylformamide. Rolidone (Nmethylpyrrolidone; NMP) and the like may be included. Accordingly, the first base film 111 may have hydrophobic properties.

The second base film 113 is provided on the first base film 111 . The second base film 113 covers the top and side surfaces of the first base film 111 . The second base film 113 may be a flexible plastic film. For example, the second base film may be a light-curable polyimide film containing cinnamate. That is, the second base film 113 may be manufactured by photocuring polyimide containing cinnamate. In this case, since the second base film 113 is manufactured by light curing, it can be cured within a shorter time than the first base film 111 . In addition, the second base film 113 may include polyethylene glycol (PEG) or 3,5-diaminobenzoic acid (DABA). Accordingly, the second base film may have hydrophilic properties. In this case, the density of the first base film 111 may be greater than that of the second base film 113 . Accordingly, the first base film 111 and the second base film 113 may be separated into two layers without being mixed with each other.

An embodiment of the present invention includes a first base film 111 and a second base film 113 covering the top and side surfaces of the first base film 111 . In this case, the second base film 113 is first photocured and the first base film 111 is thermally cured later. Therefore, in the embodiment of the present invention, since the second base film 113 is first photocured to protect the first base film 111, compared to the prior art having only the first base film 111, the first Penetration of foreign substances into the base film 111 may be prevented. Accordingly, the embodiment of the present invention can improve the quality defect of the flexible display device.

In addition, in the embodiment of the present invention, the first base film 111 has hydrophobicity, the second base film 113 has hydrophilicity, and the density of the first base film 111 is that of the second base film 113. greater than the density. Accordingly, the first base film 111 and the second base film 113 may be layer separated from each other to have a dual structure.

The buffer layer 130 is provided on the second base film 113 . The buffer layer 130 prevents moisture from penetrating into the flexible display panel 100 from the second base film 113 , which is vulnerable to moisture permeation, and thereby deteriorating the characteristics of the thin film transistors T . In addition, the buffer layer 130 prevents impurities such as metal ions from diffusing from the second base film 113 and penetrating into the active layer ACT. To this end, the buffer layer 130 may include at least one inorganic film. The buffer layer 130 may be, for example, SiO2 (silicon dioxide), SiNx (silicon nitride), SiON (silicon oxynitride), or a multi-layer thereof, but is not necessarily limited thereto.

The thin film transistor T is provided in the display area DA of the second base film 113 . The thin film transistor T includes an active layer ACT, a gate insulating layer GI, a gate electrode GE, an interlayer insulating layer ILD, a source electrode SE, and a drain electrode DE.

The active layer ACT is provided on the buffer layer 130 . The active layer ACT includes one end region A1 located on the source electrode SE side, another end region A2 located on the drain electrode DE side, and a center located between one end region A1 and the other end region A2. Area A3 may be included. The central region A3 may be formed of a semiconductor material not doped with a dopant, and one end region A1 and the other end region A2 may be formed of a semiconductor material doped with a dopant.

A gate insulating layer GI is provided on the active layer ACT. The gate insulating layer GI serves to insulate the active layer ACT and the gate electrode GE. The gate insulating layer GI covers the active layer ACT and is formed on the entire surface of the display area DA. The gate insulating layer (GI) may be formed of an inorganic layer, for example, silicon dioxide (SiO2), silicon nitride (SiNx), silicon oxynitride (SiON), or multiple layers thereof, but is not limited thereto.

The gate electrode GE is provided on the gate insulating layer GI. The gate electrode GE overlaps the central region A3 of the active layer ACT with the gate insulating layer GI interposed therebetween. The gate electrode GE may be made of, for example, molybdenum (Mo), aluminum (Al), chromium (Cr), gold (Au), titanium (Ti), nickel (Ni), neodymium (Nd), and copper (Cu). It may be a single layer or a multi-layer made of any one or an alloy thereof, but is not limited thereto.

An interlayer insulating layer ILD is provided on the gate electrode GE. The interlayer insulating layer ILD covers the gate electrode GE and may be provided on the entire surface of the base film 110 . The interlayer insulating layer (ILD) may be formed of the same inorganic layer as the gate insulating layer (GI), for example, SiO2 (silicon dioxide), SiNx (silicon nitride), SiON (silicon oxynitride), or multiple layers thereof, but is not limited thereto. don't

The source electrode SE and the drain electrode DE are spaced apart from each other on the interlayer insulating layer ILD. A first contact hole CNT1 exposing a part of one end area A1 of the active layer ACT and a part of the other end area A2 of the active layer ACT are formed in the aforementioned gate insulating film GI and interlayer insulating film ILD. An exposed second contact hole CNT2 is provided. The source electrode SE is connected to one end region A1 of the active layer ACT through the first contact hole CNT1, and the drain electrode DE connects to the active layer ACT through the second contact hole CNT2. It is connected to the other end area (A2) of.

The configuration of the thin film transistor T is not limited to the above-described example, and may be variously modified into a known configuration that can be easily implemented by those skilled in the art.

The passivation layer PAS is provided on the thin film transistor T. The passivation layer PAS serves to protect the thin film transistor T. The passivation layer (PAS) may be formed of an inorganic film, for example, silicon dioxide (SiO2), silicon nitride (SiNx), silicon oxynitride (SiON), or a multilayer thereof, but is not limited thereto.

The planarization layer PAC is provided on the passivation layer PAS positioned in the display area DA. The planarization layer PAC serves to flatten the top of the second base film 113 on which the thin film transistor T is provided. The planarization layer (PAC) is made of, for example, acrylic resin, epoxy resin, phenolic resin, polyamides resin, polyimide resin, etc. It may be made, but is not limited thereto. A third contact hole CNT3 exposing the drain electrode DE of the thin film transistor T is provided in the passivation layer PAS and the planarization layer PAC located in the display area DA. The drain electrode DE and the anode electrode AND are connected through the third contact hole CNT3.

The organic light emitting diode (OLED) is provided on the thin film transistor (T). The organic light emitting diode (OLED) includes an anode electrode (AND), an organic layer (EL), and a cathode electrode (CAT). The anode electrode AND is connected to the drain electrode DE of the thin film transistor T through the third contact hole CNT3 provided in the passivation layer PAS and the planarization layer PAC. A bank B is provided between adjacent anode electrodes AND, so that the adjacent anode electrodes AND can be electrically insulated from each other. The bank B may be formed of, for example, an organic layer such as polyimide resin, acryl resin, or benzocyclobutene (BCB), but is not limited thereto.

The organic layer EL is provided on the anode electrode AND. The organic layer EL may include a hole transporting layer, an organic light emitting layer, and an electron transporting layer. Furthermore, the organic layer EL may further include at least one functional layer for improving light emitting efficiency and/or lifetime of the light emitting layer.

The cathode electrode CAT is provided on the organic layer EL and the bank B. When voltage is applied to the anode electrode AND and the cathode electrode CAT, holes and electrons move to the organic light emitting layer through the hole transport layer and the electron transport layer, respectively, and combine with each other in the organic light emitting layer to emit light.

In FIG. 2 , the flexible display panel 100 is embodied in a top emission method, but is not limited thereto and may be implemented in a bottom emission method. In the top emission method, since the organic layer EL emits light toward the upper substrate, the transistor T can be widely provided under the bank B and the anode AND. Accordingly, the top emission method has an advantage in that the design area of the transistor T is wider than that of the bottom emission method. In the top emission method, it is preferable that the anode electrode AND is formed of a highly reflective metal material such as aluminum or a laminated structure of aluminum and ITO, and the cathode electrode CAT is formed of a transparent metal material such as ITO or IZO.

The encapsulation layer 180 is provided on the thin film transistor T and the organic light emitting diode OLED. In this case, the encapsulation layer 180 is provided smaller than the second base film 113 . Due to this, a portion of the second base film 113 may be exposed without being covered by the encapsulation layer 180 . The encapsulation layer 180 serves to protect the thin film transistor T and the organic light emitting diode OLED from external impact and to prevent moisture from penetrating into the flexible display panel 100 .

Additionally, a front adhesive layer 190 may be provided on the encapsulation layer 180 . The front adhesive layer 190 protects the thin film transistor T and the organic light emitting diode OLED from external impact and prevents moisture from permeating. The front adhesive layer 190 may be a metal layer or a barrier film, but is not necessarily limited thereto.

The gate driver 200 supplies gate signals to the gate lines according to the gate control signal input from the timing controller 400 . 1 illustrates that the gate driver 200 is formed outside one side of the display area DA of the flexible display panel 100 by a gate driver in panel (GIP) method, but is not limited thereto. That is, the gate driver 200 may be formed on the outside of both sides of the display area DA of the flexible display panel 100 by the GIP method, or may be manufactured as a driving chip and mounted on a flexible film, and may be TAB (tape automated bonding) It can also be attached to the flexible display panel 100 in this way.

The source drive IC 310 receives digital video data and a source control signal from the timing controller 400 . The source drive IC 310 converts digital video data into analog data voltages according to a source control signal and supplies them to data lines. When the source drive IC 310 is manufactured as a driving chip, it may be mounted on the flexible film 330 in a chip on film (COF) or chip on plastic (COP) method.

Since the encapsulation layer 180 is smaller than the second base film 113 , a portion of the second base film 113 may be exposed without being covered by the encapsulation layer 180 . Pads, such as data pads, are provided on a portion of the second base film 113 that is exposed and not covered by the encapsulation layer 180 . Wires connecting pads and the source drive IC 310 and wires connecting pads and wires of the circuit board 350 may be formed on the flexible film 330 . The flexible film 330 is attached to the pads using an anisotropic conducting film, and thereby the pads and wires of the flexible film 330 may be connected.

The circuit board 350 may be attached to the flexible films 330 . A plurality of circuits implemented as driving chips may be mounted on the circuit board 350 . For example, the timing controller 400 may be mounted on the circuit board 350 . The circuit board 350 may be a printed circuit board or a flexible printed circuit board.

The timing controller 400 receives digital video data and timing signals from an external system board (not shown). The timing controller 400 generates a gate control signal for controlling the operation timing of the gate driver 200 and a source control signal for controlling the source drive ICs 310 based on the timing signal. The timing controller 400 supplies gate control signals to the gate driver 200 and supplies source control signals to the source drive ICs 310 .

3 is a flowchart illustrating a method of manufacturing a flexible display device according to an exemplary embodiment of the present invention. 4A to 4F are cross-sectional views illustrating a method of manufacturing a flexible display device according to an exemplary embodiment of the present invention. This relates to a method of manufacturing a flexible display device according to an embodiment of the present invention shown in FIG. 2 . Therefore, the same reference numerals are assigned to the same components, and redundant descriptions of repetitive parts in the materials and structures of each component are omitted.

First, as shown in FIG. 4A, a first base material 111a is coated on an auxiliary substrate 115, and a second base material 113a is coated on the first base material 111a. The first base material 111a may be applied on the auxiliary substrate 115 using a slit coating method. The slit coating method is a method of uniformly applying the liquid first base material 111a on the auxiliary substrate 115 using a nozzle. When the first base material 111a is provided in a slit coating method, selective coating on the auxiliary substrate 115 is possible. Accordingly, the first base material 111a may have a size smaller than that of the auxiliary substrate 115 . However, the method of forming the first base material 111a is not necessarily limited thereto.

The second base material 113a may be applied on the first base material 111a using a slit coating method. In this case, the second base material 113a covers the top and side surfaces of the first base material 111a. The second base material 113a seals the first base material 111a and is provided on the auxiliary substrate 115 .

According to an embodiment of the present invention, the first base material 111a may have hydrophobic properties, and the second base material 113a may have hydrophilic properties. Also, the density of the first base material 111a is greater than that of the second base material 113a. Therefore, the first base material 111a and the second base material 113a are separated into layers without mixing with each other. That is, the relatively heavy first base material 111a compared to the second base material 113a is disposed on the auxiliary substrate 115, and the second base material is relatively light compared to the first base material 111a. (113a) is disposed on the first base material (111a). Accordingly, in the embodiment of the present invention, the first base film 111 and the second base film 113 having a double structure are formed by curing the layer-separated first base material 111a and the second base material 113a. can form (S101 in FIG. 3)

Second, as shown in FIG. 4B , the second base material 113a is UV-cured to form the second base film 113 . The second base material 113a may be photocurable polyimide containing cinnamate. The second base material 113a may be cured by light such as UV. Accordingly, the curing time of the second base material 113a is shorter than the curing time of the first base material 111a. That is, since the second base material 113a is cured in a short time by light, the second base material 113a may be cured in a shorter time than the first base material 111a cured by heat. The second base film 113 formed as described above functions to prevent foreign matter from penetrating into the first base material 111a. That is, since the second base film 113 is formed first to protect the first base material 111a, even if the first base material 111a is thermally cured for a long time, the second base film 113 protects the first base material 111a. Foreign matter does not penetrate into the base material 111a. (S102 in Fig. 3)

Thirdly, as shown in FIG. 4C , the first base film 111 is formed by thermally curing the first base material 111a. The first base material 111a may be thermosetting polyimide containing methacrylate. Accordingly, the first base material 111a may be cured by heat to form the first base film 111 . (S103 in Fig. 3)

Fourth, as shown in FIG. 4D , thin film transistors T are formed on the second base film 113 . First, a buffer layer 130 , an active layer ACT, and a gate insulating layer G1 are sequentially formed on the second base film 113 . Next, a gate electrode GE is formed to overlap the active layer ACT on the gate insulating layer GI disposed in the display area DA. Next, an interlayer insulating layer ILD is formed on the gate electrode GE. Finally, a source electrode SE and a drain electrode DE connected to the active layer ACT through the first and second contact holes CNT1 and CNT2 are formed on the interlayer insulating layer ILD.

Fifthly, as shown in FIG. 4E , organic light emitting diodes (OLEDs) connected to the thin film transistors (T) are formed, and an encapsulation layer 180 covering the organic light emitting diodes (OLEDs) is formed. A passivation layer (PAS) and a planarization layer (PAC) are sequentially formed on the thin film transistors (T). The anode electrode AND is formed on the thin film transistor T and is connected to the drain electrode DE through the third contact hole CNT3 provided in the passivation layer PAS and the planarization layer PAC. A bank B is formed between adjacent anode electrodes AND. The organic layer EL is formed on the anode electrode AND. The cathode electrode CAT is formed on the organic layer EL and the bank B. The encapsulation layer 180 is formed to cover the thin film transistor T and the organic light emitting diode OLED. A front adhesive layer 190 may be additionally formed on the encapsulation layer 180 .

Finally, as shown in FIG. 4F , the first and second base films 111 and 113 are separated from the auxiliary substrate 115 . In this case, the auxiliary substrate 115 and the first and second base films 111 and 113 may be separated from each other using a laser. (S104 in Fig. 3)

An embodiment of the present invention includes a first base film 111 and a second base film 113 covering the top and side surfaces of the first base film 111 . In this case, the second base film 113 is first photocured and the first base film 111 is thermally cured later. Therefore, in the embodiment of the present invention, since the second base film 113 is first photocured to protect the first base film 111, compared to the prior art having only the first base film 111, the first Penetration of foreign substances into the base film 111 may be prevented. Accordingly, the embodiment of the present invention can improve the quality defect of the flexible display device.

The present invention described above is not limited to the above-described embodiments and the accompanying drawings, and it is common in the technical field to which the present invention belongs that various substitutions, modifications, and changes are possible without departing from the technical details of the present invention. It will be clear to those who have knowledge of Therefore, the scope of the present invention is indicated by the following claims, and all changes or modifications derived from the meaning and scope of the claims and equivalent concepts should be construed as being included in the scope of the present invention.

100: flexible display panel 105: auxiliary substrate
111: first base film 113: second base film
130: buffer layer 180: encapsulation layer
190: front adhesive layer 200: gate driving unit
310: source drive IC 330: flexible film
350: circuit board 400: timing controller
T: thin film transistor OLED: organic light emitting diode

Claims (11)

a base film including a first base film and a second base film covering top and side surfaces of the first base film;
a buffer layer covering an upper surface of the base film;
a thin film transistor positioned on the buffer layer;
an organic light emitting diode disposed on the thin film transistor and electrically connected to the thin film transistor; and
An encapsulation layer covering the thin film transistor and the organic light emitting diode,
The first base film is hydrophobic, and the second base film is hydrophilic. delete According to claim 1,
The first base film is a flexible display device comprising a polyimide film containing methacrylate. According to claim 1,
The flexible display device of claim 1 , wherein the second base film is a polyimide film containing cinnamate. According to claim 1,
The flexible display device of claim 1 , wherein a density of the first base film is greater than a density of the second base film. According to claim 1,
A flexible display device further comprising a front adhesive layer provided on the encapsulation layer. coating a first base material having a first density on an auxiliary substrate;
applying a second base material having a second density lighter than the first density to be separated from the first base material while covering upper and side surfaces of the first base material having the first density;
curing the second base material with UV light to form a second base film;
forming a first base film by thermally curing the first base material using the cured second base film as a protective film; and
A method of manufacturing a flexible display device comprising separating a first base film and a second base film from the auxiliary substrate. According to claim 7,
forming thin film transistors on the second base film; and
The method of manufacturing a flexible display device further comprising forming organic light emitting diodes connected to the thin film transistors. According to claim 7,
The first base material has hydrophobic properties, and the second base material has hydrophilic properties. delete According to claim 7,
The first base material is thermally cured for a first time to form the first base film, and the second base material is cured with UV light for a second time shorter than the first time to form the second base film. Manufacturing method of flexible display device.

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