KR102434366B1 - Flexible display device - Google Patents

Abstract

A flexible display device of the present invention includes a substrate having a display area and a bending area adjacent to the display area, a wiring positioned on the substrate, extending from the display area to the bending area, and having at least a curved shape in the bending area, and a bending area of the substrate and a plurality of concave-convex patterns positioned below the wiring, wherein a width of each of the plurality of concave-convex patterns is smaller than the width of the wiring.

Description

Flexible display device {FLEXIBLE DISPLAY DEVICE}

The present invention relates to a display device including an uneven portion on a flexible substrate.

Recently, as we enter the information age in earnest, the field of display that visually expresses electrical information signals has developed rapidly, and in response to this, various display devices with excellent performance of thinness, light weight, and low power consumption have been developed. is being developed

Specific examples of such a display device include a liquid crystal display (LCD), an organic light emitting display (OLED), an electro-luminescent display, an electrophoretic display (EPD), an electrowetting display (EWD), etc. can be heard In particular, an organic light emitting display device is a next-generation display device having self-luminous characteristics, and has superior characteristics in terms of viewing angle, contrast, response speed, power consumption, and the like, compared to a liquid crystal display device.

Recently, a flexible display device that is manufactured to display an image even if it is bent like paper by forming a display unit and wiring on a flexible substrate such as plastic, which is a flexible material, has been attracting attention.

While manufacturing a flexible display device using a flexible substrate, it is an important task to secure flexibility of the substrate, various insulating layers formed on the substrate, and wiring formed of a metal material.

As the size and resolution of the flexible display device progresses, a space for arranging wiring becomes insufficient. In particular, when the non-display area is increased to arrange wiring, it may be difficult to realize miniaturization, thinness, and narrow bezel/zero bezel shape. Accordingly, the inventors of the present invention have attempted to implement a shape of narrowing or eliminating the bezel/edge by bending or folding the flexible display device.

When the flexible display device is bent or folded, the substrate on which the wiring is formed is bent or folded, and the wiring may be cracked due to stress. If the wiring is damaged, normal signal transmission is not performed, so that the thin film transistor or the organic light emitting diode may not operate normally, which may lead to a defect in the flexible display device.

Also, when the flexible display device is bent or folded, the substrate may be bent or folded and the substrate may also be cracked due to stress. When a portion of the substrate is damaged, the generated damage may be propagated to other regions of the substrate and may be propagated to wiring on the substrate, which may lead to defects in the flexible display device.

Accordingly, the inventors of the present invention have devised a new structure in which damage to the substrate and wiring can be minimized when the flexible display device is bent or folded.

The tasks of the present specification are not limited to the tasks mentioned above, and other tasks not mentioned will be clearly understood by those skilled in the art from the following description.

A flexible display device according to an exemplary embodiment includes a substrate having a display area and a bending area adjacent to the display area, a wiring positioned on the substrate, extending from the display area to the bending area, and having a curved shape at least in the bending area and a plurality of concavo-convex patterns provided in the bending region of the substrate and positioned under the wiring, wherein a width of each of the plurality of concavo-convex patterns is smaller than the width of the wiring.

The concave-convex pattern has a surface area expansion structure that increases the surface area of the substrate to minimize bending stress transmitted to the wiring.

The concave-convex pattern is positioned corresponding to the wiring having a curved shape.

In the surface area expansion structure, the concave-convex pattern convexly protrudes on the lower surface of the substrate.

In the surface area expansion structure, the concave-convex pattern is concavely deposited on the upper surface of the substrate.

The lower surface of the wiring having a curved shape is a wiring that protrudes convexly and fills the concave-convex pattern.

In the upper surface of the wiring having a curved shape, a portion corresponding to the concave-convex pattern is depressed.

The concavo-convex pattern is arranged more densely as it approaches the bending axis of the bending region.

A display device according to another embodiment of the present invention includes a display device including a flexible substrate, wherein the flexible substrate includes concavo-convex portions including a plurality of concavo-convex structures to resist bending stress generated when the flexible substrate is bent. (Resistance) to minimize the breakage (crack) of the flexible substrate and the wiring on the flexible substrate.

The concave-convex structure expands a surface area in a bending region of the flexible substrate to distribute bending stress applied to the flexible substrate.

A width of one uneven structure is smaller than a width of the wiring.

An interval between one concave-convex structure and another adjacent concave-convex structure is 0.5 μm to 3 μm.

The wiring is configured such that bending stress applied to the wiring in contact with the concave-convex structure is distributed by the convex portion of the wiring.

The convex portion of the wiring is located on one surface where the concave-convex structure contacts the wiring.

The wiring is configured such that the elongation of the wiring is improved by providing a concave portion corresponding to the convex portion on the other surface of the wiring.

The concave-convex structure is positioned on one surface of the flexible substrate in contact with the wiring and the other surface facing the wiring to minimize bending stress transmitted to the wiring.

According to the present invention, since the flexible substrate has an uneven portion including a plurality of uneven structures, damage to the flexible substrate and wiring on the substrate may be minimized.

Effects according to the embodiments of the present invention are not limited by the contents exemplified above, and more various effects are included in the present specification.

1 is a plan view illustrating a flexible display device according to an exemplary embodiment.
FIG. 2 is a cross-sectional view of the flexible display device taken along line I-I' of FIG. 1 .
FIG. 3 is a plan view for explaining a wiring structure for a region A of FIG. 2 .
4 is a cross-sectional view of a wiring structure taken along line II-II' of FIG. 3 .
FIG. 5 is a flowchart for explaining a method of forming a wiring in a bending region and a substrate having the surface area expansion structure of FIG. 4 ;
6 and 8 are cross-sectional views illustrating a wiring structure included in a flexible display device according to another exemplary embodiment.
9 is a flowchart for explaining a method of forming a wiring in a bending region and a substrate having the surface area expansion structure of FIG. 8 ;

Advantages and features of the present specification and methods of achieving them will become apparent with reference to the embodiments described below in detail in conjunction with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but will be implemented in various different forms, and only these embodiments allow the disclosure of the present invention to be complete, and common knowledge in the technical field to which the present invention belongs It is provided to fully inform the possessor of the scope of the invention, and the present invention is only defined by the scope of the claims.

The shapes, sizes, proportions, angles, numbers, etc. disclosed in the drawings for explaining the embodiments of the present specification are exemplary, and thus the present specification is not limited to the illustrated matters. Like reference numerals refer to like elements throughout. In addition, in describing the present invention, if it is determined that a detailed description of a related known technology may unnecessarily obscure the subject matter of the present invention, the detailed description thereof will be omitted. When 'including', 'having', 'consisting', etc. mentioned in this specification are used, other parts may be added unless 'only' is used. When a component is expressed in the singular, the case in which the plural is included is included unless specifically stated otherwise. In interpreting the components, it is interpreted as including an error range even if there is no separate explicit description.

In the case of a description of the positional relationship, for example, when the positional relationship of two parts is described as 'on', 'on', 'on', 'beside', etc., 'right' Alternatively, one or more other parts may be positioned between two parts unless 'directly' is used. Reference to a device or layer “on” another device or layer includes any intervening layer or other device directly on or in the middle of another device. When it is described that a component is “connected”, “coupled” or “connected” to another component, the component may be directly connected or connected to the other component, but other components may be interposed between each component. It should be understood that each component may be “interposed” or “connected,” “coupled,” or “connected” through another component.

Although first, second, etc. are used to describe various elements, these elements are not limited by these terms. These terms are only used to distinguish one component from another. Accordingly, the first component mentioned below may be the second component within the spirit of the present invention.

Like reference numerals refer to like elements throughout.

The size and thickness of each component shown in the drawings are illustrated for convenience of description, and the present invention is not necessarily limited to the size and thickness of the illustrated component.

Each feature of the various embodiments of the present invention may be partially or wholly combined or combined with each other, technically various interlocking and driving are possible, and each of the embodiments may be implemented independently of each other or may be implemented together in a related relationship. may be

Hereinafter, the present invention will be described in detail with reference to the drawings.

1 is a plan view illustrating a flexible display device according to an exemplary embodiment.

1 , the flexible display device 100 includes an active area A/A and an inactive area I/A surrounding the display area A/A. . A pixel array including organic light emitting devices 160 is disposed in the display area A/A. Although the flexible display device 100 is illustrated as having one display area A/A, there may be a plurality of display areas A/A.

The display area A/A is an area in which an image is displayed in the flexible display device 100 , and the display area A/A includes the organic light emitting device 160 and various driving devices for driving the organic light emitting device 160 . can be placed.

The non-display area I/A may be disposed around the display area A/A. Specifically, the non-display area I/A may surround the display area A/A. Although the non-display area I/A is illustrated as enclosing the rectangular display area A/A, the shape and arrangement of the display area A/A and the non-display area adjacent to the display area A/A The shape and arrangement of (I/A) are not limited thereto. For example, in the case of a display device of a wearable device by a user, it may have a circular shape such as a general wrist watch, and also in a free-form display device applicable to a vehicle instrument panel, etc. of the present embodiments. Concepts may apply.

The non-display area I/A is, for example, an area in which circuits such as the wiring 170 supplying a signal such as the scan line SL and the gate driver 191 are formed. The gate driver 191 may be disposed in a GIP shape. Also, the data driver may be disposed in the non-display area I/A.

A pad 195 is disposed in the non-display area I/A. For example, the pad 195 is disposed on one side of the substrate 110 in the non-display area I/A. The pad 195 is a metal pattern to which an external module, for example, a flexible printed circuit board (FPCB), a chip on film (COF), or the like is bonded. Although the pad 195 is illustrated as being disposed on one side of the substrate 110 , the shape and arrangement of the pad 195 are not limited thereto.

A wiring 170 is disposed in the non-display area I/A. The wiring 170 is a wiring 170 for transmitting a signal (voltage) from an external module bonded to the pad 195 to a circuit unit such as the display area A/A or the gate driver 191 . For example, various signals for driving the gate driver 191 may be transmitted through the wiring 170 , such as a data signal, a high potential voltage VDD, and a low potential voltage VSS. In this case, the wiring 170 may be simultaneously formed of the same material as various conductive components disposed in the display area A/A.

The bending area B/A (or folding area) is an area that can be bent when the flexible display device 100 is bent (or folded). In the present invention, the bending area B/A is located in the non-display area I/A adjacent to the display area A/A. The bending area B/A is an area for disposing the pad 195 and the external module bonded to the pad 195 under the substrate 110 . That is, as the bending region B/A is bent (in the direction of the arrow in FIG. 1 ), the external module bonded to the pad 195 of the substrate 110 moves to the lower portion of the substrate 110 , and the upper portion of the substrate 110 . External modules may not be recognized when viewed from In addition, as the bending area B/A is bent, the size of the non-display area I/A viewed from the upper portion of the substrate 110 may be reduced, so that a narrow bezel may be implemented. However, in the present invention, although it has been described that the bending area B/A is included in the non-display area I/A, the present invention is not limited thereto, and the bending area B/A is all or part of the display area A/A. may be positioned in the , and since the display area A/A itself can be bent in various directions, the bending area B/A located in the display area A/A may also enjoy the effects mentioned in the present invention.

The bending area B/A may be bent according to a specific radius of curvature based on a bending axis (or a folding axis). Specifically, the bending axis may be the X-axis. When the bending area BA is bent based on the bending axis, the bending area BA may form a part of a circle or an ellipse. In this case, the radius of curvature of the bending area BA means a radius of a circle or an ellipse corresponding to a part of the circle or ellipse formed by the bending area BA. In the present invention, the bending axis in the X-axis direction is positioned in the bending area B/A, and the display area A/A is positioned perpendicular to the bending axis by extending from the bending area B/A in the Y-axis direction. Although described as an example, the present invention is not limited thereto.

FIG. 2 is a cross-sectional view of the flexible display device taken along line I-I' of FIG. 1 . In the flexible display device 100 according to an embodiment of the present invention shown in FIG. 2 , the light emitted from the organic light emitting diode 160 is emitted to the upper portion of the flexible display device through the cathode 163 top emission. ) type of flexible display device. However, the present invention is not limited to the top-emission flexible display device 100, and may be applied to the bottom-emission and dual side-emission flexible display devices.

As shown in FIG. 2 , the substrate 110 supports various components of the flexible display device 100 . A pixel array including organic light emitting devices 160 is disposed on the substrate 110 .

Since the substrate 110 may be made of a plastic material having flexibility (or flexibility), it is a flexible substrate 110 that is bendable. In this case, when the flexible substrate 110 is bent based on the bending axis, the flexible display device may be bent. For example, when the substrate 110 is made of polyimide (PI), the manufacturing process proceeds in a situation where a support substrate made of glass is disposed under the substrate 110, and after the manufacturing process is completed, the support substrate is released ( can be released). In addition, after the support substrate is released, a back plate for supporting the flexible substrate may be disposed under the flexible substrate 110 .

The thin film transistor 130 is disposed on the flexible substrate 110 . The thin film transistor 130 includes an active layer 131 made of polysilicon, a gate electrode 134 , a source electrode 132 , and a drain electrode 133 . The thin film transistor 130 is a driving thin film transistor and has a top gate structure in which the gate electrode 134 is disposed on the active layer 131 . For convenience of description, only a driving thin film transistor among various thin film transistors that may be included in the flexible display device 100 is illustrated, but other thin film transistors such as a switching thin film transistor may also be included in the flexible display device 100 . Also, for convenience of description, although the thin film transistor 130 has been described as having a coplanar structure, the thin film transistor 130 may be implemented with other structures such as a staggered structure.

The active layer 131 of the thin film transistor 130 is disposed on the flexible substrate 110 . The active layer 131 includes a channel area CA in which a channel is formed when the thin film transistor 130 is driven, a source area SA and a drain area DA on both sides of the channel area CA. ) is included. The channel region CA, the source region SA, and the drain region DA are defined by ion doping (impurity doping).

The active layer 131 of the thin film transistor 130 may be made of polysilicon. Accordingly, polysilicon is formed by depositing an amorphous silicon (a-Si) material on the flexible substrate 110 and performing a dehydrogenation process, a crystallization process, an activation process, and a hydrogenation process, and patterning the polysilicon to form an active material. A layer 131 may be formed. When the active layer 131 is made of polysilicon, the thin film transistor 130 may be an LTPS thin film transistor 130 using low temperature poly-silicon (LTPS). Since the polysilicon material has high mobility, when the active layer 131 is made of polysilicon, energy consumption is low and reliability is excellent.

The gate insulating layer 112 is disposed on the active layer 131 and the flexible substrate 110 . The gate insulating layer 112 may be formed of a single layer of inorganic silicon nitride (SiNx) or silicon oxide (SiOx) or a multilayer of silicon nitride (SiNx) or silicon oxide (SiOx). The gate insulating layer 112 has a contact hole through which the source electrode 132 and the drain electrode 133 respectively contact the source area SA and the drain area DA of the active layer 131 .

The gate electrode 134 is disposed on the gate insulating layer 112 . A metal layer such as molybdenum (Mo) is formed on the gate insulating layer 112 and the metal layer is patterned to form a gate electrode 134 . The gate electrode 134 is disposed on the gate insulating layer 112 to overlap the channel region CA of the active layer 131 .

An interlayer insulating layer 115 is disposed on the gate electrode 134 . The interlayer insulating layer 115 may be formed of a single layer of inorganic silicon nitride (SiNx) or silicon oxide (SiOx) or a multilayer of silicon nitride (SiNx) or silicon oxide (SiOx). A contact hole is formed in the interlayer insulating layer 115 to contact each of the source electrode 132 and the drain electrode 133 to the source area SA and the drain area DA of the active layer 131 .

The source electrode 132 and the drain electrode 133 are disposed on the interlayer insulating layer 115 . The source electrode 132 and the drain electrode 133 may be formed of a conductive metal material, for example, may have a three-layer structure of titanium (Ti)/aluminum (Al)/titanium (Ti). Each of the source electrode 132 and the drain electrode 133 is connected to each of the source area SA and the drain area DA of the active layer 131 through a contact hole.

The storage capacitor 120 is disposed on the flexible substrate 110 . The storage capacitor 120 includes a first electrode 121 disposed on the gate insulating layer 112 and a second electrode 122 disposed on the interlayer insulating layer 115 . The first electrode 121 of the storage capacitor 120 is simultaneously formed of the same material as the gate electrode 134 of the thin film transistor 130 , and the second electrode 122 of the storage capacitor 120 is formed of the thin film transistor 130 . It may be simultaneously formed of the same material as the source electrode 132 and the drain electrode 133 of Accordingly, since the storage capacitor 120 may be formed during the manufacturing process of the thin film transistor 130 without the need for a separate additional process, efficiency exists in terms of process cost and process time.

The passivation layer 116 may be disposed on the thin film transistor 130 and the storage capacitor 120 . The passivation layer 116 is an insulating layer for protecting the thin film transistor 130 and the storage capacitor 120 . The passivation layer 116 may be formed of a single layer of inorganic silicon nitride (SiNx) or silicon oxide (SiOx) or a multilayer of silicon nitride (SiNx) or silicon oxide (SiOx). The passivation layer 116 has a contact hole through which the anode 161 of the organic light emitting diode 160 is connected to the thin film transistor 130 . The passivation layer 116 is not a necessary component and may be omitted depending on the design of the flexible display device 100 .

A planarization layer 113 is disposed on the passivation layer 116 . The planarization layer 113 is an insulating layer for planarizing the upper portion of the thin film transistor 130 , and may be made of an organic material. Since the passivation layer 116 is formed along the shape of the upper portions of the thin film transistor 130 and the storage capacitor 120 , the passivation layer 116 is not planarized by the thin film transistor 130 and the storage capacitor 120 , and a step difference is not achieved. may exist. Accordingly, the planarization layer 113 planarizes the upper portions of the thin film transistor 130 and the storage capacitor 120 , so that the organic light emitting diode 160 can be formed more reliably. A contact hole for exposing the source electrode 132 of the thin film transistor 130 is formed in the planarization layer 113 .

The organic light emitting diode 160 is disposed on the planarization layer 113 . The organic light emitting diode 160 is formed on the planarization layer 113 and is electrically connected to the source electrode 132 of the thin film transistor 130. The anode 161, the organic layer 162 disposed on the anode 161 and the organic layer ( and a cathode 163 formed on 162 . Since the flexible display device 100 is a top-emission flexible display device, the anode 161 reflects the light emitted from the organic layer 162 toward the cathode 163 and supplies holes to the organic layer 162 . It may include a transparent conductive layer for However, it may be defined that the anode 161 includes only a transparent conductive layer and the reflective layer is a separate component from the anode 161 . The organic layer 162 is an organic layer 162 for emitting light of a specific color, and may include one of a red organic emission layer, a green organic emission layer, a blue organic emission layer, and a white organic emission layer. If the organic layer 162 includes a white organic light emitting layer, a color filter for converting white light from the white organic light emitting layer into light of a different color may be disposed on the organic light emitting device 160 . In addition, the organic layer 162 may further include various organic layers 162 such as a hole transport layer, a hole injection layer, an electron injection layer, an electron transport layer, in addition to the organic emission layer. The cathode 163 may be made of a transparent conductive material, and may include, for example, a transparent conductive oxide such as Indium-Zinc-Oxide (IZO) or ytterbium (Yb).

Bank 114 is disposed on anode 161 and planarization layer 113 . The bank 114 defines a pixel area in a manner of dividing adjacent pixel areas in the display area A/A. The bank 114 may be formed of an organic material. For example, the bank 114 may be made of polyimide, acryl, or benzocyclobutene (BCB)-based resin, but is not limited thereto.

An encapsulation unit may be formed on the organic light emitting device 160 to protect the organic light emitting device 160, which is vulnerable to moisture, from being exposed to moisture. For example, the encapsulation unit may have a structure in which inorganic layers and organic layers are alternately stacked.

Hereinafter, the structure of the curved wiring 171 and the concave-convex portion 180 disposed in the bending region B/A will be described in more detail with reference to FIGS. 3 and 4 together.

FIG. 3 is a plan view for explaining a wiring structure for a region A of FIG. 2 . 4 is a cross-sectional view of a wiring structure taken along line II-II' of FIG. 3 .

As shown in FIG. 3 , a wiring 171 is disposed in the bending area B/A. The wiring disposed in the bending area B/A may extend from the display area A/A to the bending area B/A and be positioned on the flexible substrate 110 . Accordingly, the wiring 171 may be formed of the same conductive material as the conductive component disposed in the display area A/A. For example, the wiring 171 may be formed of the same conductive material as the source electrode 132 and the drain electrode 133 , but is not limited thereto and may be formed of a different material.

A portion of the wiring 171 disposed in the bending area B/A may be a wiring having a linear shape at both ends. However, the remaining portion of the wiring 171 crossing the bending region B/A may have a curved shape capable of resisting bending stress when the flexible display device 100 is bent. The curved wiring 171 has, for example, a diamond-shaped split/group wiring design, and may have a much lower electrical resistance compared to a single wiring-shaped wiring structure. Also, in the curved wiring 171 , even if a portion of the wiring is damaged, the remaining wiring may function as a preliminary passage. However, the shape of the wiring 171 disposed in the bending area B/A is not limited thereto, and may be provided in at least one of a sine wave, a square wave sawtooth, a wave, a hatched shape, or a shape similar thereto.

In order to form the wiring 171 in the bending region B/A, a conductive material is deposited on the substrate 110, and then the conductive material is patterned in the shape of the wiring to be formed by an etching process or the like. can be In this case, since there may be a limit in the precision of the process, there may be a limit in narrowing the gap between the wirings 171 . Accordingly, since a large amount of space is required to form the wirings 171 in the bending area B/A, the area of the non-display area I/A increases and it may be difficult to implement a narrow bezel. In particular, in the wiring 171 connected to the pad portion to which the external module is bonded, the wiring 171 extending from the display area A/A to the non-display area I/A may be disposed in a complex structure, so that the non-display area (I/A) requires more space. Accordingly, by bending the bending area B/A in the non-display area I/A, the non-display area I/A having the wiring having a complicated structure is positioned below the flexible display device 100 to form a narrow bezel This can be implemented.

In this case, the curved wirings 171 disposed in the bending area B/A may be damaged (or cracked) when the flexible display device 100 is bent. Also, the substrate 110 disposed adjacent to the wiring 171 under the curved wiring 171 in the bending area B/A is also damaged (or cracked) when the flexible display device 100 is bent. ) can be In particular, the bending stress applied to the wiring 171 having a curved shape near a bending axis in the bending area B/A may be greatest. Accordingly, the probability that the curved wiring 171 is damaged near the bending axis may increase. Accordingly, in order to prevent damage to the curved wiring 171 and the substrate 110 in the bending region B/A, the concave-convex portion 180 is disposed.

As shown in FIG. 4 , the concave-convex portion 180 is included in the flexible substrate 110 . The concavo-convex portion 180 may be integrally provided on the flexible substrate 110 in the bending region B/A. In this case, the concave-convex portion 180 disposed in the bending area B/A includes a plurality of concave-convex structures 181 .

The plurality of concavo-convex structures 181 (or concavo-convex patterns) may be included in the concavo-convex portion in the shape of, for example, a cylinder or a hemisphere. In this case, the radius of the concave-convex structure 181 may be 0.5 μm to 3 μm. As the radius of one concave-convex structure 181 increases in consideration of the range of the radius, the surface area of the concavo-convex portion may be larger.

In addition, the interval between one concave-convex structure 181 and another adjacent concave-convex structure 181 may be 0.5 μm to 3 μm. Considering the range of this interval, the narrower the distance between one concave-convex structure 181 and another adjacent concave-convex structure 181, the more densely the plurality of concavo-convex structures 181 provided in the concave-convex structure 180 is. can be placed. Accordingly, as one concave-convex structure 181 and another concave-convex structure 181 are densely disposed, the surface area of the concavo-convex structure 180 may increase.

That is, the concave-convex portion 180 may increase the surface area in the bending region B/A by adjusting the shape, size, and spacing between the plurality of concave-convex structures 181 . Accordingly, the surface area of the substrate 110 in the bending area B/A may also be increased. In this case, the substrate 110 may be bent based on a bending axis in the bending area B/A. Accordingly, the substrate 110 may receive bending stress in the bending region B/A.

Bending stress is a type of force that can act on the entire area subjected to the force. In this case, as the total area increases, the force received per unit area may decrease. Therefore, as the surface area increases, the total area subjected to the force increases, so that the bending stress can be distributed over the increased surface area. Therefore, the bending stress per unit area can be reduced.

In other words, the concave-convex portion 180 may include a plurality of concave-convex structures 181 to increase the surface area, and the flexible substrate 110 includes the concave-convex portion 180 in the bending region B/A to increase the surface area. can be expanded Accordingly, the plurality of concave-convex structures 181 may increase the surface area of the flexible substrate 110 in the bending region B/A, thereby distributing bending stress received when the flexible substrate 110 is bent. Accordingly, the uneven portion 180 may resist bending stress generated when the bending region B/A of the flexible substrate 110 is bent. Accordingly, when the flexible display device 100 is bent, damage to the flexible substrate 110 having the concave-convex portion 180 may be minimized.

Also, the wiring 171 may be positioned on the flexible substrate 110 having the concave-convex portion 180 in the bending region B/A. In this case, since the bending stress is distributed by the plurality of uneven structures 181 corresponding to the wiring in the bending area B/A, the bending stress transmitted to the wiring through the flexible substrate 110 may be minimized. Accordingly, when the flexible display device 100 is bent, damage to the wiring 171 in the bending area B/A may be minimized.

Also, the width of one concave-convex structure 181 may be smaller than the width of one curved wiring 171 in the bending area B/A. In this case, the curved wiring 171 in the bending area B/A may correspond to the plurality of concave-convex structures 181 . Accordingly, the bending stress applied to the wiring 171 having a curved shape may be minimized by dispersing the bending stress of the plurality of concave-convex structures 181 . Accordingly, when the flexible display device 100 is bent, damage to the wiring 171 in the bending area B/A may be further minimized.

Hereinafter, the arrangement of the concave-convex portion 180 will be described in more detail.

As shown in FIG. 4 , the flexible substrate 110 includes the concavo-convex portion 180 in the bending area B/A. Here, the concavo-convex portion 180 may be referred to as or configured as a nano-scale pattern. The plurality of concave-convex structures 181 of the concave-convex portion 180 may be provided on the lower surface (or the rear surface) of the flexible substrate 110 . At this time, the plurality of concave-convex structures 181 are partially provided on the lower surface of the flexible substrate 110, and have a surface area expansion structure 190 to widen the surface area of the flexible substrate 110 in the bending area B/A. are doing

Specifically, the surface area expansion structure 190 may be implemented in which a plurality of concave-convex structures 181 are partially provided on the lower surface of the flexible substrate 110 . The plurality of concave-convex structures 181 may convexly protrude from the lower surface of the flexible substrate 110 . In this case, the plurality of concave-convex structures 181 may be disposed to correspond to a specific region in which the curved wiring 171 is disposed on the upper surface of the flexible substrate 110 . Accordingly, the concave-convex structure 181 may be disposed only on the lower surface of a specific region of the flexible substrate 110 on which the curved wiring 171 is disposed. Accordingly, the plurality of concave-convex patterns may partially increase the surface area of the lower surface of the flexible substrate 110 to correspond to a specific region in which the curved wiring 171 is located. That is, the plurality of concave-convex structures 181 may increase the surface area of a portion of the lower surface of the flexible substrate 110 on which the curved wiring 171 is positioned on the upper surface, and may not increase the surface area of the other portion.

When the flexible substrate 110 is bent based on the bending axis in the bending region B/A, the flexible substrate 110 may be subjected to bending stress. In this case, the surface area expansion structure 290 including the plurality of concave-convex structures 181 on a portion of the lower surface of the flexible substrate 110 may partially increase the surface area of the lower surface of the substrate 110 .

Accordingly, the surface area expansion structure 190 on a portion of the lower surface of the flexible substrate 110 may distribute bending stress received when the flexible substrate 110 is bent in a portion of the lower surface of the flexible substrate 110 . Accordingly, damage to the flexible substrate 110 may be minimized.

In addition, since the bending stress is distributed through the flexible substrate 110 , the bending stress transmitted to the curved wiring 171 on the upper surface of the flexible substrate 110 may be minimized. Accordingly, when the flexible display device 100 is bent, damage to the curved wiring 171 in the bending area B/A may be minimized.

In this case, the flexible substrate 110 having the surface area expansion structure 190 may be formed by a specific process.

FIG. 5 is a flowchart illustrating a method of forming a wiring in a bending region and a substrate having the surface area expansion structure of FIG. 4 . 5 is a flowchart for sequentially explaining a process for forming the surface area expansion structure 190 on the lower surface of the flexible substrate 110 and forming the curved wiring 171 in the bending region B/A. to be.

As shown in FIG. 5 , the lower mother substrate is etched. (S1)

The lower mother substrate is a substrate for supporting the flexible substrate 110 and components disposed on the flexible substrate 110 during the manufacturing process of the flexible display device 100 . Accordingly, the lower mother substrate may be made of a material having rigidity, for example, glass, but is not limited thereto.

The lower mother substrate includes a display area and a non-display area. In this case, the display area of the lower mother substrate corresponds to the display area A/A of the flexible display device 100 , and the non-display area of the lower mother substrate corresponds to the non-display area I/A of the flexible display device 100 . do.

In this case, a portion corresponding to the bending area B/A in the non-display area I/A of the flexible display device 100 among the non-display areas of the lower mother substrate may be etched. The lower mother substrate may be subjected to an etching process by applying a physical impact through a laser. In this case, when the surface of the lower mother substrate is partially etched by the laser, a concave and convex pattern may be formed on the lower mother substrate.

In addition, the lower mother substrate is an etching process using a photoresist used in a pattern forming process using a mask, and the surface of the lower mother substrate may be partially etched. In this case, a photoresist is formed on the surface of the lower mother substrate, and a portion of the surface of the lower mother substrate without the photoresist may be etched through dry-etching. In this case, the material used in the dry-etching process may include, for example, hydrogen fluoride (HF) gas, but is not limited thereto. After the dry-etching process is completed, the photoresist on the surface of the lower ledger substrate is removed. Accordingly, the surface of the lower mother substrate may be partially etched to form a concave-convex pattern. In this case, the concave-convex pattern formed on the lower mother substrate may then correspond to the bending region B/A of the flexible display device 100 .

After the lower mother substrate is etched, a sacrificial layer is formed on the lower mother substrate. (S2) When the laser is irradiated to the sacrificial layer, the bonding of the interface is decomposed and the adhesive force with the flexible substrate 110 to be described later may be weakened. The sacrificial layer may have, for example, a structure in which a silicon nitride (SiNx) layer and a silicon oxide (SiOx) layer are stacked, and may be formed by depositing on the surface of the lower mother substrate. In this case, the sacrificial layer may be formed on a surface having a concave-convex pattern. Accordingly, the sacrificial layer may be formed inside the concave-convex pattern formed by etching the lower mother substrate.

Next, a flexible substrate is formed on the sacrificial layer. (S3)

The flexible substrate 110 supports various components of the flexible display device 100 . The flexible substrate 110 may be made of a plastic material, for example, polyimide (PI) or photo acryl (photo acryl), but is not limited thereto. When the flexible substrate 110 is made of polyimide (PI), the flexible substrate 110 may be formed in such a way that the polyimide (PI) is applied to the lower mother substrate. In this case, the material forming the flexible substrate 110 may be formed inside the concave-convex pattern formed by partially etching the surface of the lower mother substrate.

Accordingly, in response to the concave and convex pattern of the lower mother substrate, the convexly protruding concave-convex structure 181 of the flexible substrate 110 may be formed. In this case, the convexly protruding concave-convex structure 181 of the flexible substrate 110 may be formed to correspond to the bending region B/A of the flexible display device 100 .

Next, wiring is formed on the flexible substrate 110 . (S4)

A display unit including a circuit unit and an organic light emitting device is formed on the flexible substrate 100 . Also, a wiring 171 having a curved shape is formed to correspond to the bending area B/A of the flexible substrate 100 . In this case, the curved wiring 171 is formed on the upper surface of the flexible substrate 110 having the concave-convex structure 181 on the lower surface in the bending region B/A. Accordingly, a convexly protruding concave-convex pattern is positioned on the lower surface of the flexible substrate 110 , and the curved wiring 171 is positioned on the upper surface of the flexible substrate 110 .

Finally, the lower mother substrate is removed. (S5)

After the components constituting the flexible display device 100 are formed on the flexible substrate 110 formed on the lower mother substrate, a laser is placed on the lower surface of the lower mother substrate, that is, on the opposite surface of the upper surface on which the sacrificial layer is disposed on the lower mother substrate. investigate In this case, the adhesive force of the sacrificial layer between the flexible substrate 100 and the lower mother substrate may be reduced. Accordingly, the adhesive force of the sacrificial layer is reduced by laser irradiation, so that the lower mother substrate may be removed without damaging the flexible substrate 110 and components of the flexible display device on the lower mother substrate.

6 to 8 are cross-sectional views illustrating a wiring structure included in a flexible display device according to still another exemplary embodiment of the present invention. 6 to 8 are different from those of FIG. 4 only in the structures of the curved wirings 171,271 and the concavo-convex portions 280, 380, and 480 provided in the bending area B/A of the flexible display device 100. However, since the rest of the structure is the same, a redundant description will be omitted.

As shown in FIG. 6 , the flexible substrate 110 includes the concavo-convex portion 280 in the bending area B/A. The plurality of concave-convex structures 281 of the concavo-convex portion 280 may be provided on the lower surface (or rear surface) of the flexible substrate 110 . At this time, the plurality of concave-convex structures 281 are provided on the lower surface of the flexible substrate 110, and have a surface area expansion structure 290 that widens the surface area of the flexible substrate 110 in the bending area B/A. .

Specifically, the surface area expansion structure 290 may be implemented in which a plurality of concave-convex structures 281 are provided entirely on the lower surface of the flexible substrate 110 . The plurality of concave-convex structures 281 may convexly protrude from the lower surface of the flexible substrate 110 . In this case, the plurality of concave-convex structures 281 may be entirely disposed in the bending area B/A of the flexible substrate 110 . Accordingly, the plurality of concave-convex structures 281 may increase the overall surface area of the lower surface of the flexible substrate 110 in the bending area B/A.

When the flexible substrate 110 is bent based on the bending axis in the bending region B/A, the flexible substrate 110 may be subjected to bending stress. In this case, the surface area expansion structure 290 having the plurality of concave-convex structures 281 on the lower surface of the flexible substrate 110 may increase the surface area of the lower surface of the flexible substrate 110 . In particular, the surface area expansion structure 290 in which the plurality of concave-convex structures 281 are formed in the entire bending region B/A of the flexible substrate 110 is the surface area expansion structure 190 in which the plurality of concave-convex structures 181 are partially formed. ), the surface area of the flexible substrate 110 may be increased.

Accordingly, the surface area expansion structure 290 on the lower surface of the flexible substrate 110 may distribute the bending stress received when the flexible substrate 110 is bent to a larger surface area of the lower surface of the flexible substrate 110 . Accordingly, damage to the flexible substrate 110 may be further minimized.

Also, a curved wiring 271 is positioned on the upper surface of the flexible substrate 110 having the surface area expansion structure 290 in the bending region B/A. The width of one uneven structure 281 provided on the lower surface of the flexible substrate 110 may be smaller than the width of the curved wiring 171 disposed on the upper surface of the flexible substrate 110 . In this case, the plurality of concave-convex structures 281 may correspond to the curved wiring 171 . That is, the plurality of concave-convex structures 281 are located on one surface of the flexible substrate 110 in contact with the curved wiring 171 and the other surface opposite to that of the flexible substrate 110 .

Accordingly, the surface area expansion structure 290 on the lower surface of the flexible substrate 110 may distribute the bending stress received when the flexible substrate 110 is bent over a large surface area of the lower surface of the flexible substrate 110 . Accordingly, the bending stress transmitted to the curved wiring 171 on the upper surface of the flexible substrate 110 through the flexible substrate 110 may be minimized. Accordingly, when the flexible display device 100 is bent, damage to the curved wiring 171 in the bending area B/A may be minimized.

As shown in FIG. 7 , the flexible substrate 110 includes the concavo-convex portion 380 in the bending area B/A. The plurality of concave-convex structures 381 of the concavo-convex portion 380 may be provided on the lower surface (or the rear surface) of the flexible substrate 110 . In this case, the plurality of concave-convex structures 181 are partially provided on the lower surface of the flexible substrate 110, and have a surface area expansion structure 390 that widens the surface area of the flexible substrate 110 in the bending area B/A. are doing

Specifically, the surface area expansion structure 390 may be implemented by partially providing a plurality of concave-convex structures 381 on the lower surface of the flexible substrate 110 . The plurality of concave-convex structures 381 may convexly protrude from the lower surface of the flexible substrate 110 . In this case, the plurality of concave-convex structures 381 may be arranged more densely as they are closer to the bending axis in the bending area B/A of the flexible substrate 110 . Accordingly, the surface area of the lower surface of the flexible substrate 110 may increase as the plurality of concave-convex structures 381 are closer to the bending axis in the bending area B/A.

When the flexible substrate 110 is bent based on the bending axis in the bending region B/A, the flexible substrate 110 may be subjected to bending stress. In particular, the closer to the bending axis of the bending region B/A, the greater the bending stress that the flexible substrate 110 receives. At this time, as the surface area expansion structure 390 having a plurality of concave-convex structures 381 on the lower surface of the flexible substrate 110 is closer to the bending axis in the bending area B/A, the concave-convex structures 381 are densely arranged. The surface area of the lower surface of the flexible substrate 110 may be increased. Accordingly, the surface area expansion structure 390 on the lower surface of the flexible substrate 110 may distribute the bending stress received when the flexible substrate 110 is bent over a large surface area of the lower surface of the flexible substrate 110 . In particular, the bending stress received near the bending axis of the bending area B/A may be more easily distributed by the uneven structure 381 densely disposed near the bending axis. Accordingly, damage to the flexible substrate 110 may be minimized.

Also, since the bending stress is distributed through the flexible substrate, the bending stress transmitted to the curved wiring 171 on the upper surface of the flexible substrate 110 may be minimized. Accordingly, when the flexible display device 100 is bent, damage to the curved wiring 171 in the bending area B/A may be minimized.

As shown in FIG. 8 , the flexible substrate 110 includes an uneven portion 480 in the bending area B/A. The plurality of concave-convex structures 481 of the concave-convex portion 480 may be provided on the upper surface (or the front surface) of the flexible substrate 110 . In this case, the plurality of concave-convex structures 481 are partially provided on the upper surface of the flexible substrate 110, and have a surface area expansion structure 490 to widen the surface area of the flexible substrate 110 in the bending area B/A. are doing

Specifically, the surface area expansion structure 490 may be implemented in which a plurality of concave-convex structures 481 are partially provided on the upper surface of the flexible substrate 110 . The plurality of concave-convex structures 481 may be concavely deposited on the upper surface of the flexible substrate 110 . In this case, the plurality of concave-convex structures 481 may be covered by the curved wiring 271 . That is, the curved wiring 271 may be positioned on the upper surface of the flexible substrate 110 to correspond to the plurality of concave-convex structures 481 .

Accordingly, the lower surface of the curved wiring 271 may convexly protrude to fill the space provided by the plurality of concave-convex structures 481 on the upper surface of the flexible substrate 110 . In this case, a portion corresponding to the concave-convex structure 481 may be concavely settled on the upper surface of the curved wiring 271 .

That is, the curved wiring 271 has a convex portion on one surface in contact with the plurality of concave-convex structures 481 . In addition, the curved wiring 271 may include a concave portion corresponding to the convex portion on the other surface opposite to one surface of the curved wiring 271 . Accordingly, the concave-convex structure 481 may increase the surface area of the upper surface of the flexible substrate 110 positioned under the curved wiring 271 , and the curved wiring 271 corresponding to this may also have a partially enlarged surface area. A surface area expansion structure 490 is provided.

When the flexible substrate 110 is bent based on the bending axis in the bending region B/A, the flexible substrate 110 may be subjected to bending stress. In this case, the plurality of concave-convex structures 481 may distribute bending stress received when the flexible substrate 110 is bent to a portion of the upper surface of the flexible substrate 110 .

In addition, even when bending stress is transmitted to the curved wiring 271 in contact with the plurality of concave-convex structures 481 , the bending stress is applied to the bending-shaped wiring 271 by the convex portions of the curved wiring 271 . It can be dispersed in convex portions. That is, since the bending stress is distributed not only by the uneven structure 481 but also by the convex portions of the curved wiring 271 , the degree to which the bending stress is dispersed may be further increased.

In this case, a portion in which the plurality of uneven structures 481 is not present on the upper surface of the flexible substrate 110 may have a lower bending stress that can be dispersed than a portion in which the plurality of uneven structures 481 are provided. In addition, since the convex portion of the curved wiring 271 is also located in the portion where the plurality of concave-convex structures 481 are located, bending stress may be further dispersed. Accordingly, damage to the portion of the flexible substrate 110 corresponding to the region in which the curved wiring 271 is located may be further minimized than damage to the remaining portion of the flexible substrate 110 .

Since bending stress is distributed through the convex portions of the flexible substrate 110 and the curved wiring 271, the bending stress transmitted to the curved wiring 271 on the upper surface of the flexible substrate 110 can be further minimized. . In addition, the curved wiring 271 has a concave portion, so that the dense concave portion can be stretched when the flexible substrate is bent. That is, the curved wiring 271 may have a concave portion to improve elongation. Accordingly, when the flexible display device 100 is bent, damage to the curved wiring 171 in the bending area B/A may be minimized.

In this case, the flexible substrate 110 having the surface area expansion structure 490 on the upper surface and the curved wiring 271 having the convex portion may be formed by a specific process.

FIG. 9 is a flowchart for explaining a method of forming a wiring in a bending region and a substrate having the surface area expansion structure 490 of FIG. 8 . 9 shows a method of forming a surface area expansion structure 490 on the upper surface of the flexible substrate 110 and forming a curved wiring 271 having a convex portion in the bending region B/A in sequence. It is a flowchart for explanation.

As shown in FIG. 9 , the lower mother substrate is etched. (S1')

The lower mother substrate is a substrate for supporting the flexible substrate 110 and components disposed on the flexible substrate 110 during the manufacturing process of the flexible display device 100 . Accordingly, the lower mother substrate may be made of a material having rigidity, for example, glass, but is not limited thereto.

The lower mother substrate includes a display area and a non-display area. In this case, the display area of the lower mother substrate corresponds to the display area A/A of the flexible display device 100 , and the non-display area of the lower mother substrate corresponds to the non-display area I/A of the flexible display device 100 . do.

In this case, a portion corresponding to the bending area B/A in the non-display area I/A of the flexible display device 100 among the non-display areas of the lower mother substrate may be etched. The lower mother substrate may be subjected to an etching process by applying a physical impact through a laser. In this case, when the surface of the lower mother substrate is partially etched by the laser, a convex concave-convex pattern may be formed on the lower mother substrate.

In addition, the lower mother substrate is an etching process using a photoresist used in a pattern forming process using a mask, and the surface of the lower mother substrate may be partially etched. In this case, a photoresist is formed on the surface of the lower mother substrate, and a portion of the surface of the lower mother substrate without the photoresist may be etched through dry-etching. In this case, as a material used in the dry-etching process, for example, HF gas may be used, but is not limited thereto. After the dry-etching process is completed, the photoresist on the surface of the mother substrate is removed. Accordingly, the surface of the lower mother substrate may be partially etched to form a convex and concave-convex pattern. In this case, the convex concavo-convex pattern formed on the lower mother substrate may correspond to the bending region B/A of the flexible display device 100 .

After the lower mother substrate is etched, a sacrificial layer is formed on the lower mother substrate. (S2') When the laser is irradiated to the sacrificial layer, the bonding of the interface is decomposed and the adhesive force with the flexible substrate 110, which will be described later, may be weakened. The sacrificial layer may have, for example, a structure in which a silicon nitride (SiNx) layer and a silicon oxide (SiOx) layer are stacked, and may be formed by depositing on the surface of the lower mother substrate. In this case, the sacrificial layer may be formed on a surface having a convex concave-convex pattern. Accordingly, the sacrificial layer may be formed to have a convex pattern by covering the convex concavo-convex pattern formed by etching the lower mother substrate.

Next, a flexible substrate is formed on the sacrificial layer. (S3')

The flexible substrate 110 supports various components of the flexible display device 100 . The flexible substrate 110 may be made of a plastic material, for example, polyimide (PI) or photo-acryl, but is not limited thereto. When the flexible substrate 110 is made of polyimide (PI), the flexible substrate 110 may be formed in such a way that the polyimide (PI) is applied to the lower mother substrate. In this case, the material forming the flexible substrate 110 may cover the surface of the convex and concave-convex pattern formed by partially etching the surface of the lower mother substrate. Accordingly, the concave-convex structure 481 of the flexible substrate 110 may be formed to correspond to the convex-convex pattern of the lower mother substrate. In this case, the concave-convex structure 481 of the flexible substrate 110 may be formed to correspond to the bending area B/A of the flexible display device 100 .

Then, the lower mother substrate is removed. (S4')

The laser is irradiated to the lower surface of the lower mother substrate, that is, the opposite surface of the upper surface on which the sacrificial layer is disposed on the lower raw steel substrate. In this case, the adhesive force of the sacrificial layer between the flexible substrate 100 and the lower mother substrate may be reduced. Accordingly, the adhesive force of the sacrificial layer is reduced by laser irradiation, so that the lower mother substrate may be removed without damage to the flexible substrate 110 on the lower mother substrate.

Thereafter, the flexible substrate is turned over and placed on the other supporting substrate. (S5')

The flexible substrate from which the lower mother substrate has been removed is turned over and placed on the support substrate. At this time, the flexible substrate is positioned so that one surface on which the concave-convex structure 181 is formed becomes the upper surface. That is, the other surface of the flexible substrate without the concave-convex structure 181 is disposed in contact with the support substrate. In this case, the supporting substrate may be the same substrate as the lower mother substrate, and may be made of any material having rigidity as long as it can support components disposed on the flexible substrate.

Finally, wiring is formed on the flexible substrate. (S6')

A display unit including a circuit unit and an organic light emitting device is formed on the flexible substrate 100 . Also, the wiring 171 having a curved shape is formed to correspond to the bending area B/A of the flexible substrate 100 . In this case, the curved wiring 271 is formed on the upper surface of the flexible substrate 110 having the concave-convex structure 181 on the upper surface in the bending region B/A. Accordingly, a concavely depressed concave-convex pattern is positioned on the upper surface of the flexible substrate 110 , and a convex portion may be formed in the curved wiring 171 formed on the upper surface of the flexible substrate 110 to correspond to the concave-convex pattern. That is, the convex portion may be formed on the lower surface of the curved wiring 171 in contact with the upper surface of the flexible substrate 110 . In addition, the curved wiring 171 may have a concave portion formed on the upper surface of the curved wiring 171 to correspond to the convex portion.

Embodiments of the present specification may be described as follows.

According to embodiments of the specification, a flexible substrate including a pixel array implemented on an upper surface; and a nano-scale pattern on at least one of a lower surface and an upper surface of the substrate, wherein the substrate includes a bending part, and the substrate is a conventional substrate without the nano-scale pattern. To provide a flexible display device having improved flexibility compared to the present invention.

It may further include a coating layer covering the bending portion of the substrate, and the thickness of the coating layer may be thinner than that of the conventional substrate without the nanometer-sized pattern.

It may further include a wiring disposed on the upper surface of the substrate and connected to the pixel array, and a nanometer-sized pattern of the substrate may be implemented to correspond to a shape of the wiring.

It may further include a wiring disposed on the upper surface of the substrate and connected to the pixel array, wherein the wiring may be implemented as a nanometer-sized pattern corresponding to the nanometer-sized pattern of the substrate.

Although the embodiments of the present invention have been described in more detail with reference to the accompanying drawings, the present invention is not necessarily limited to these embodiments, and various modifications may be made within the scope without departing from the technical spirit of the present invention. Accordingly, the embodiments disclosed in the present invention are not intended to limit the technical spirit of the present invention, but to explain, and the scope of the technical spirit of the present invention is not limited by these embodiments. Therefore, it should be understood that the embodiments described above are illustrative in all respects and not restrictive. The protection scope of the present invention should be construed by the claims, and all technical ideas within the scope equivalent thereto should be construed as being included in the scope of the present invention.

100: flexible display device
110: flexible substrate
171, 271: curved wiring
180, 280, 380, 480: irregularities
181, 281, 381, 481: uneven structure
190, 290, 390, 490: Surface area expansion structure

Claims (20)

a substrate including a display area and a bending area adjacent to the display area;
a wiring disposed on the substrate, extending from the display area to the bending area, and having a curved shape at least in the bending area; and
It is provided in the bending region of the substrate and includes a plurality of concave-convex patterns positioned under the wiring,
The width of each of the plurality of concave-convex patterns is smaller than the width of the wiring,
The plurality of concavo-convex patterns are more densely disposed as they are closer to a bending axis of the bending region. The method of claim 1,
The concave-convex pattern includes a surface area expansion structure for increasing a surface area of the substrate to minimize bending stress transmitted to the wiring. 3. The method of claim 2,
The concave-convex pattern is positioned to correspond to the wiring having the curved shape. 4. The method of claim 3,
The structure for increasing the surface area may include a flexible display in which a concave-convex pattern convexly protrudes from a lower surface of the substrate. 4. The method of claim 3,
In the structure for increasing the surface area, the concave-convex pattern is concavely deposited on an upper surface of the substrate. 6. The method of claim 5,
A lower surface of the wiring having the curved shape is a wiring that convexly protrudes and fills the concavo-convex pattern. 7. The method of claim 6,
a portion corresponding to the concave-convex pattern is concavely depressed on the upper surface of the wiring having the curved shape. delete A display device comprising: a flexible substrate having a display area and a bending area adjacent to the display area;
The flexible substrate has a concave-convex portion including a plurality of concave-convex structures,
The plurality of concave-convex structures are arranged more densely as they are closer to the bending axis of the bending region to resist bending stress generated when the flexible substrate is bent, so that the flexible substrate and the wiring on the flexible substrate are formed. A flexible display device configured to minimize cracks. 10. The method of claim 9,
The concave-convex structure expands a surface area in a bending region of the flexible substrate to distribute bending stress applied to the flexible substrate. 11. The method of claim 10,
A width of one of the concave-convex structures is smaller than a width of the wiring. 12. The method of claim 11,
A distance between the one concave-convex structure and another adjacent concave-convex structure is 0.5 μm to 3 μm. 12. The method of claim 11,
The wiring is configured to be in contact with the concave-convex structure so that bending stress applied to the wiring is distributed by the convex portion of the wiring. 14. The method of claim 13,
The convex portion of the wiring is positioned on a surface of the uneven structure in contact with the wiring. 15. The method of claim 14,
The wiring is configured to include a concave portion corresponding to the convex portion on the other surface of the wiring to improve elongation of the wiring. 12. The method of claim 11,
The concave-convex structure is positioned on the other surface opposite to one surface of the flexible substrate in contact with the wiring to minimize bending stress transmitted to the wiring. a flexible substrate including a display unit on which a pixel array implemented on an upper surface is disposed and a bending unit adjacent to the display unit; and
At least one of the lower surface and upper surface of the substrate includes a nano-scale pattern (nano-scale pattern),
A flexible display device in which the nanometer-sized pattern is more densely disposed as it is closer to the bending axis of the bending part, so that the substrate has improved flexibility compared to a conventional substrate without the nanometer-sized pattern. 18. The method of claim 17,
The flexible display device further includes a coating layer covering the bending portion of the substrate, wherein the coating layer has a thinner thickness than the conventional substrate without the nanometer-sized pattern. 18. The method of claim 17,
The flexible display device further includes a wiring disposed on the upper surface of the substrate and connected to the pixel array, wherein a nanometer-sized pattern of the substrate corresponds to a shape of the wiring. 18. The method of claim 17,
The flexible display device further includes a wiring disposed on the upper surface of the substrate and connected to the pixel array, wherein the wiring is implemented in a nanometer-sized pattern corresponding to the nanometer-sized pattern of the substrate.

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