KR102646659B1 - Flexible display device and method of fabricating thereof - Google Patents

Abstract

The present invention relates to a display device that can be manufactured in various shapes, including a flexible substrate including a display area and a pad area; a plurality of through holes provided in the pad area to form a bending area; a display element formed in the display area; and a plurality of signal wires disposed between through holes in the bending area and connected to the display element.

Description

Flexible display device and method of manufacturing the same {FLEXIBLE DISPLAY DEVICE AND METHOD OF FABRICATING THEREOF}

The present invention relates to a flexible substrate and a method of manufacturing the same. It relates to a flexible substrate capable of various shapes and a method of manufacturing the same.

In general, flat panel displays such as liquid crystal displays and organic electroluminescence displays are used as large-area display devices such as TVs, but are also used in mobile communication devices such as mobile phones.

Meanwhile, with the advancement of technology, the development of wearable computers is currently accelerating. These wearable computers refer to computers that can be worn naturally on the body, such as clothes, watches, glasses, or accessories. Therefore, wearable computers are formed in various shapes depending on the object to which they are applied, and display devices provided in such wearable computers must also be formed in various shapes like the shape of the wearable computer.

However, there are currently many difficulties in manufacturing display devices of various shapes that can be applied to wearable computers due to problems in processing and processing.

The present invention was made in consideration of the above points, and its purpose is to provide a display device capable of various shapes by applying and patterning a polyimide solution on a carrier substrate and a method of manufacturing the same.

Another object of the present invention is to provide a display device and a method of manufacturing the same that can minimize the bezel by folding some areas to the back by forming a plurality of through holes in a flexible substrate in the bending area and forming signal wires between the through holes. It is done.

In order to achieve the above object, a display device according to the present invention includes a flexible substrate including a display area and a pad area; a plurality of through holes provided in the pad area to form a bending area; a display element formed in the display area; and a plurality of signal wires disposed between through holes in the bending area and connected to the display element.

The flexible substrate can be configured in various shapes, including round, and the bending area is folded to the back of the flexible substrate.

Additionally, the display device according to the present invention includes the steps of forming a sacrificial layer on a carrier substrate; forming a polyimide film by applying a polyimide solution to the entire sacrificial layer; patterning the polyimide film to form a flexible substrate including a display area, a dummy area, and a plurality of through holes formed in the dummy area; forming a display element in the display area and forming a plurality of signal wires between through holes in the dummy area; and peeling the flexible substrate from the carrier substrate.

In the present invention, a polyimide solution is applied and patterned on a carrier substrate, and a display element is formed on the patterned flexible substrate, making it possible to manufacture various display devices.

Additionally, in the present invention, the bezel of the display device can be minimized by forming a plurality of through holes in the flexible substrate in the bending area and forming signal wires between the through holes to fold a portion of the display device to the rear.

1 is a plan view schematically showing a display device according to the present invention.
Figure 2 is a cross-sectional view taken along line II' of Figure 1.
Figure 3 is a cross-sectional view taken along line II-II' of Figure 1.
Figure 4 is a flow chart showing a manufacturing method of a display device according to the present invention.
5A to 5D are plan views showing a method of manufacturing a display device according to the invention.
6A to 6D are cross-sectional views showing a method of manufacturing a display device according to the invention.

The advantages and features of the present invention and methods for achieving them will become clear by referring to the embodiments described in detail below along with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below and will be implemented in various different forms. These embodiments only serve to ensure that the disclosure of the present invention is complete and that common knowledge in the technical field to which the present invention pertains is not limited. It is provided to fully inform those who have 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 embodiments of the present invention are illustrative, and the present invention is not limited to the matters shown. Like reference numerals refer to like elements throughout the specification. Additionally, in describing the present invention, if it is determined that a detailed description of related known technologies may unnecessarily obscure the gist of the present invention, the detailed description will be omitted. When 'includes', 'has', 'consists of', 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 plural is included unless specifically stated otherwise.

When interpreting a component, it is interpreted to include the margin of error even if there is no separate explicit description.

In the case of a description of a positional relationship, for example, if the positional relationship of two parts is described as 'on top', 'on the top', 'on the bottom', 'next to', etc., 'immediately' Alternatively, there may be one or more other parts placed between the two parts, unless 'directly' is used.

In the case of a description of a temporal relationship, for example, if a temporal relationship is described as 'after', 'successfully after', 'after', 'before', etc., 'immediately' or 'directly' Unless used, non-consecutive cases may also be included.

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

Each feature of the various embodiments of the present invention can be combined or combined with each other, partially or entirely, and various technological interconnections and operations are possible, and each embodiment can be implemented independently of each other or together in a related relationship. It may be possible.

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

The present invention provides a flexible display device. In particular, the present invention provides a flexible display device that can be formed into various shapes.

The most important component for manufacturing display devices of various shapes is the substrate. Since various electrodes and wiring formed inside the display device are formed in minute sizes, they do not significantly affect the shape of the display device. Additionally, various layers, such as an insulating layer or a protective layer, are formed by printing or a photolithograph process, so they can be formed into various shapes depending on the shape of the photomask used. Additionally, polarizers used in liquid crystal displays or organic electroluminescent displays can be easily cut into desired shapes.

However, the substrate cannot be cut into the desired shape. For example, in the case of a glass substrate, it is a very hard material, so in order to cut it, it is necessary to use mechanical cutting means such as a cutting wheel and a grinding device. However, these mechanical devices can be used to cut the glass into various shapes, such as circles, ovals, and acute angles. It was impossible to form it into a polygonal shape. Moreover, a plurality of display devices are formed on a mother substrate basis. Accordingly, after forming a display device having a desired shape in each of the plurality of regions of the mother substrate, the substrate is first cut into a rectangular shape to include the region where the display device is formed, and the substrate is separated into a plurality of pieces, and the separated substrates are again shaped into the desired shape. must be cut. Therefore, it was impossible to manufacture a display device of the desired shape using a glass substrate.

Additionally, when manufacturing a display device using a flexible substrate, a polyimide-based polymer solution is applied on a carrier substrate such as glass to form a flexible substrate and display elements are formed thereon. Next, the display device is completed by separating the flexible substrate from the carrier substrate. Therefore, even in the case of a display device using a flexible substrate, not only the flexible substrate but also the carrier substrate must be cut, making it impossible to manufacture a display device of the desired shape.

Moreover, when cutting a flexible substrate with a cutting device, external force is applied to the side surface of the flexible substrate, that is, the cut surface, which may cause cracks to occur in the side surface, and these cracks propagate inside the display device, causing damage to the display device. or foreign substances such as air and moisture penetrate through cracks, causing the display device to deteriorate.

In the present invention, display devices of various shapes are manufactured using a flexible substrate. In particular, in the present invention, the flexible substrate and display device are formed into desired shapes without a mechanical cutting process. In particular, in the present invention, a display device of a desired shape can be manufactured without a cutting process by applying a polyimide solution on a carrier substrate and then patterning it into a desired shape.

The present invention is not applied to a specific display device, but may be applied to various display devices such as an organic electroluminescent display device, a liquid crystal display device, and an electrophoretic display device.

Figure 1 is a diagram showing a display device 100 according to the present invention. The display device at this time is an organic electroluminescent display device.

As shown in Figure 1, the present invention consists of a display area (AA) and a pad area (NA) provided on a substrate 110 made of a transparent plastic material such as polyimide.

At this time, the substrate 110 is provided with rounded corners, and the display area AA may also be configured with the same rounded corners as the substrate 110. The pad area NA is formed at the top, bottom, and left and right ends of the display area AA.

A display element 101 is provided in the display area AA. Although not shown in the drawing, the display element 101 includes a plurality of sub-pixels defined by a plurality of gate lines and data lines to implement an actual image, and each sub-pixel (SPX) includes a driving thin film that is a switching element. A transistor, a switching thin film transistor, a sensing thin film transistor, and an auxiliary thin film transistor are placed. In addition, an image realization unit is formed in each sub-pixel (SPX) to display an actual image using an image signal input from the outside through a thin film transistor.

When the display device 100 is an organic electroluminescent display device, the image realization portion includes an organic light emitting layer, and when the display device 100 is a liquid crystal display device, the image realization portion includes a liquid crystal layer. Additionally, when the display device 100 is an electrophoretic display device, the image realization unit includes electrophoresis. As such, the display device 100 of the present invention is not limited to a specific type of display device but may be applied to a variety of display devices.

A bending area (B) is formed at the top of the pad area (NA). The bending area B may be formed in an area extending from a rounded rectangular shape toward the top, but is not limited to this and may be formed at any position in the pad area NA. A plurality of signal wires 148 are formed in the bending area (B), and a plurality of flexible printed circuits (FPCs) may be attached to the ends of the bending area (B). At this time, a data driver is mounted on each FPC, and a data control signal input from an external timing control unit is supplied to the display area AA through the signal wire 148.

Although not shown in the drawing, a plurality of pads are formed at the top of the bending area (B), so that when the FPC is attached to the bending area (B), the circuit wiring of the FPC is electrically connected to the pads.

The bending area B is folded toward the back of the substrate 110, and the FPC is fixed to the back of the substrate 110. In this way, as the substrate 110 is folded and the FPC is fixed to the rear surface of the substrate 110, the area of the pad area NA is reduced, thereby making it possible to reduce the bezel that forms the outline of the display device.

A plurality of through holes 162 are formed in the bending area (B). The through hole 162 is formed in a vertical direction, that is, in a rectangular shape extending from the display area AA to the end of the bending area B, completely penetrating the substrate 110, and extends in the left and right directions of the bending area B. They are placed at a set distance apart.

The through hole 162 in the bending area (B) serves as a fold line that allows the substrate 110 to be easily folded. In general, flexibility and folding of the substrate 110 have different meanings. Flexible means that the substrate 110 is bent to a set curvature, but folded means that it is completely bent to the opposite side of the substrate. Therefore, the curvature of the fold is much greater than that of the flexible.

The substrate 110 made of a polyimide-based plastic material bends well, but does not bend beyond a set curvature. Of course, it is possible to forcibly bend the curvature beyond the set curvature, but in this case, strong stress is applied to the bent area, resulting in damage to the area. Therefore, in order to fold the substrate 110 toward the back side, the material of the substrate 110 must be changed or a separate component that absorbs or blocks stress due to folding must be formed in the folding area.

On the other hand, in the present invention, by forming a plurality of through holes 162 in the bending portion B, the corresponding area can be smoothly folded without changing the material of the substrate 110 or adding a separate component. That is, when the bending area is folded, the tensile stress (or compressive stress) applied to the substrate 110 in the bending area (B) is reduced by the plurality of through holes 162. Accordingly, since the substrate 110 can be bent beyond the set curvature, the substrate 110 can be folded at the bending area B toward the rear side of the substrate 110.

Meanwhile, a signal wire 148 is disposed between the through holes 162 of the bending area B, and the display area AA is connected to the display element 110 through a plurality of pads, and the signal wire 148 is connected to the display element 110. Through this, various control signals output from the data driver can be transmitted to the display element 110 of the display area (AA).

The signal wire 148 may be a Vdd wire for applying a high potential voltage, a Vdata wire for applying a driving voltage, a Vref wire for applying a reference voltage, and a Vss wire for applying a low potential voltage, but is not limited thereto.

FIG. 2 is a cross-sectional view taken along line II' of FIG. 1, and is a diagram specifically showing the structure of a sub-pixel of the display element 110 according to the present invention. The organic electroluminescent display device 100 according to the present invention will be described in more detail with reference to this drawing. At this time, although the drawing illustrates an organic electroluminescent display device as an example, the present invention is not limited to an organic electroluminescent display device and may also be applied to a liquid crystal display device or an electrophoretic display device.

As shown in FIG. 2, a light shielding layer 111 is formed on the substrate 110, and the light shielding layer 111 is formed over the entire first substrate 110 (i.e., the display area ( A buffer layer 122 is formed throughout the AA) and dummy area (NA). A driving thin film transistor is disposed on the butter layer 122. In addition, although not shown in the drawing, thin film transistors such as a switching thin film transistor, a sensing thin film transistor, and an auxiliary thin film transistor may be formed in the display area AA.

The substrate 110 may be made of a transparent and flexible plastic material such as polyimide, but is not limited to this and any transparent and flexible material may be used.

The light blocking layer 111 is formed of a metal such as Cr, Mo, Ta, Cu, Ti, Al, or Al alloy, but is not limited thereto. The light blocking layer 111 blocks light input to the driving thin film transistor and prevents off current from occurring in the driving thin film transistor due to the photoelectric effect.

The buffer layer 122 may be composed of a single layer made of an inorganic layer or a plurality of layers made of an inorganic layer and an organic layer. At this time, inorganic materials such as SiOx or SiNx can be used as the inorganic layer, and organic materials such as photoacrylic can be used as the organic layer, but are not limited thereto.

The driving thin film transistor is disposed in each of the plurality of pixel areas formed in the display area AA. The driving thin film transistor includes a semiconductor layer 112 formed on the buffer layer 122, a gate insulating layer 124 formed throughout the first substrate 110 on which the semiconductor layer 112 is formed, and the gate insulating layer ( 124) a gate electrode 114 formed thereon, an interlayer insulating layer 126 formed over the entire first substrate 110 to cover the gate electrode 114, and a contact hole formed in the interlayer insulating layer 126. It consists of a source electrode 116 and a drain electrode 117, each in contact with the semiconductor layer 112.

The semiconductor layer 112 may be formed of an oxide semiconductor such as crystalline silicon or IGZO (Indium Gallium Zinc Oxide). In this case, the oxide semiconductor layer consists of a channel layer in the central region and a doped layer on both sides to form the source electrode 116. and the drain electrode 117 is in contact with the doped layer. Additionally, the semiconductor layer 112 may be made of amorphous silicon or an organic semiconductor material.

The gate electrode 114 may be formed of a single layer or multiple layers made of metal such as Cr, Mo, Ta, Cu, Ti, Al, or Al alloy, and the gate insulating layer 124 may be formed of SiO _x or SiN x. It may be composed of a single layer made of the same inorganic material or a two-layer inorganic layer of SiOx and SiNx. In the drawing, the gate insulating layer 124 is formed over the entire first substrate 110, but it may be formed only on the lower part of the gate electrode 114. Additionally, the interlayer insulating layer 126 may be composed of a single layer or multiple layers made of inorganic materials such as SiO _x and SiN x, but is not limited thereto.

Additionally, the source electrode 116 and the drain electrode 117 may be made of Cr, Mo, Ta, Cu, Ti, Al, or an Al alloy, but are not limited thereto.

Meanwhile, in the drawings and the above description, the driving thin film transistor is configured with a specific structure, but the driving thin film transistor of the present invention is not limited to the structure shown, and any currently known structure of thin film transistor can be applied.

A protective layer 128 is formed over the entire first substrate 111 on which the driving thin film transistor is formed. The protective layer 128 may be composed of a single layer made of an inorganic material or a plurality of layers made of an inorganic material and an organic material. Although not shown in the drawing, a planarization layer made of organic material may be formed on the protective layer 128.

An organic light emitting element (E) is formed on the protective layer 128 and is electrically connected to the drain electrode 117 of the thin film transistor through a contact hole formed in the protective layer 128.

The organic light emitting device (E) includes a first electrode 132 connected to the drain electrode 117 of the thin film transistor through a contact hole, an organic light emitting layer 134 formed on the first electrode 132, and the organic light emitting layer. It consists of a second electrode 136 formed on (134).

The first electrode 132 is made of a single layer or multiple layers of metals such as Ca, Ba, Mg, Al, Ag, etc. or alloys thereof, and is connected to the drain electrode 117 of the thin film transistor to receive an image signal from the outside. approved. At this time, the first electrode 132 acts as a reflective film and can reflect light emitted from the organic light emitting layer 134 upward (i.e., in the opposite direction of the first substrate 111). Additionally, the first electrode 132 may be made of a transparent metal oxide such as indium tin oxide (ITO) or indium zinc oxide (IZO).

The second electrode 136 is made of transparent metal oxide such as ITO or IZO, but is not limited thereto. Additionally, the second electrode 136 may be composed of a single layer or multiple layers of metals such as Ca, Ba, Mg, Al, Ag, or alloys thereof. At this time, the second electrode 136 acts as a reflective film and can reflect light emitted from the organic light-emitting layer 154 in a downward direction (i.e., toward the first substrate 111).

When the organic electroluminescent display device according to the present invention is a bottom emitting display device in which light emitted from the organic light emitting layer 134 is output in the downward direction, that is, toward the first substrate 110, the first electrode 132 is a transparent metal oxide. and the second electrode 136 is made of a metal or metal compound that reflects light. When the organic electroluminescent display device is a top-emitting display device in which light emitted from the organic light-emitting layer 134 is output upward, The first electrode 132 is made of a metal or metal compound that functions as a reflective film, and the second electrode 136 is made of a transparent metal oxide.

The organic light emitting layer 134 may be formed in the R, G, and B pixels and may be an R-organic light-emitting layer that emits red light, a G-organic light-emitting layer that emits green light, or a B-organic light-emitting layer that emits blue light. It may be a white organic light-emitting layer formed over the layer and emitting white light. When the organic light emitting layer 134 is a white organic light emitting layer, R, G, and B color filter layers are formed in the upper area of the white organic light emitting layer of the R, G, and B pixels to convert white light emitted from the white organic light emitting layer into red light, green light, and blue light. Convert. The white organic light-emitting layer may be formed by mixing a plurality of organic materials that each emit monochromatic light of R, G, and B, or may be formed by stacking a plurality of organic light-emitting layers that each emit monochromatic light of R, G, and B.

The organic light-emitting layer may be an inorganic light-emitting layer made of an inorganic light-emitting material, such as quantum dots, rather than an organic light-emitting material.

In addition to the light emitting layer, the organic light emitting layer 134 may be formed with an electron injection layer and a hole injection layer, which respectively inject electrons and holes into the light emitting layer, and an electron transport layer and a hole transport layer, which respectively transport the injected electrons and holes to the organic layer.

A bank layer (bank layer) 130 is formed in the boundary area of the pixel above the protective layer 128. The bank layer 130 is a type of partition wall that divides each pixel and prevents lights of different colors output from adjacent pixels from being mixed together.

In the drawing, a portion of the bank layer 130 is formed on the first electrode 132, but the bank layer 130 is formed only on the planarization layer 128 and the first electrode 132 is formed on the bank layer 130. It may be formed by extending over the side of . In this way, when the first electrode 132 is extended on the side of the bank layer 130, the first electrode 132 is also formed in the corner area of the boundary between the bank layer 130 and the protective layer 128, so this A signal is also applied to the organic light emitting layer 134 in the area, so that light is emitted in the corner area, and an image can be displayed in this area as well. Accordingly, it is possible to minimize the non-display area in which the image within the pixel is not displayed.

An encapsulation layer 152 is formed on the light emitting device E and the bank layer 130. The encapsulation layer 152 may be composed of a single layer composed of an inorganic layer such as SiNx and SiX, but may be composed of an inorganic layer and photoacrylic, polyethylene terephthalate, polyethylene naphthalate, polycarbonate, polyimide, polyethylene sulfonate, and polyoxymethylene. , It may be composed of a double layer of an organic layer such as polyarylate, or it may be composed of a plurality of layers of an inorganic layer/organic layer/inorganic layer.

A protective film 150 is attached to the encapsulation layer 152 using a transparent adhesive (not shown). Any material can be used as the adhesive as long as it has good adhesion and good heat resistance and water resistance. However, in the present invention, a thermosetting resin such as an epoxy-based compound, an acrylate-based compound, or an acrylic rubber can be used. Additionally, a photocurable resin or a thermosetting resin may be used as the adhesive, and in this case, the adhesive is cured by applying light such as ultraviolet rays or heat.

The protective film 150 is an encapsulation cap for encapsulating the electroluminescent display device, and can be used as a PS (Polystyrene) film, PE (Polyethylene) film, PEN (Polyethylene Naphthalate) film, or PI (Polyimide) film. You can.

FIG. 3 is a cross-sectional view taken along line II-II' of FIG. 1, showing the structure of the bending area (B).

As shown in FIG. 3, a plurality of through holes 162 are formed in the substrate 110 of the pad area NA, and a buffer layer 122 and a gate insulating layer 124 are formed throughout the substrate 110. And an interlayer insulating layer 126 is formed.

A plurality of signal wires 148 are disposed on the interlayer insulating layer 126 between the through holes 162. The plurality of signal wires 148 may be made of metal such as Cr, Mo, Ta, Cu, Ti, Al, or Al alloy, but are not limited thereto. That is, the signal wire 148 may be formed of the same material as the source electrode 116 and the drain electrode 117 of the thin film transistor formed in the display area AA.

Additionally, the signal wire 148 may be formed on the gate insulating layer 124 between the through holes 162. At this time, the signal wire 148 may be formed of the same material as the gate electrode 114 of the thin film transistor. Additionally, the signal wire 148 may be formed on the substrate 110 between the through holes 162. At this time, the signal wire 148 may be formed of the same material as the light blocking layer 111.

A protective layer 128 and an encapsulation layer 152 are formed on the signal wire 148, and a protective film 150 is attached thereto using an adhesive.

As described above, in the present invention, only the signal wire 148 and various insulating layers are formed in the bending area (B), and thus the bending area (B) has the worst flexibility among the configurations. However, in the present invention, since the through hole 162 is formed in the substrate 110 between the signal wires 148 in the bending area (B), the tensile stress or compressive stress of the substrate 110 can be reduced, thereby allowing bending. It is possible to improve the bendability of the substrate 110 in the area B, and as a result, the display device 100 can be folded to a desired degree in the bending area B.

Figure 4 is a flow chart showing the manufacturing method of the display device 100 according to the present invention.

As shown in Figure 4, first prepare a carrier substrate (S101). A sacrificial layer is formed on it (S102).

The carrier substrate is a back plate, to which a flexible substrate is attached and keeps the flexible substrate flat when the flexible substrate is transported or the manufacturing process of a display device progresses. The carrier substrate may be made of glass or metal, but is not limited thereto.

The sacrificial layer is used to peel off the flexible substrate placed on the carrier substrate, and may be made of amorphous silicon, but is not limited thereto.

Afterwards, a polyimide (PI) solution is applied entirely on the sacrificial layer (S103). At this time, the application of the polyimide solution can be done in various ways. For example, the polyimide can be coated by various methods such as spin coating, screen coating, roll coating, dispensing, etc.

Next, the applied polyimide is cured and then patterned into a desired shape to form a flexible substrate (S104). Patterning of polyimide can be accomplished through wet etching and dry etching exposure processes. That is, photoresist is laminated and developed on the polyimide film applied to the carrier substrate to form a photoresist pattern of the desired shape, and then the exposed polyimide film is etched with an etchant to form a flexible substrate of the desired shape. .

In addition, photoresist is laminated and developed on the polyimide film applied to the carrier substrate to form a photoresist pattern of the desired shape, and then the exposed polyimide film is etched with an etching gas to form a flexible substrate of the desired shape. there is.

Additionally, a flexible substrate of a desired shape can be formed by forming a polyimide film using photosensitive polyimide, irradiating light and directly developing the photosensitive polyimide film.

Afterwards, a display element is formed in the display area on the formed flexible substrate (S105). The display device is formed through a general photolithography process and may be composed of an organic electroluminescent display device with the structure shown in FIG. 2. Additionally, a liquid crystal display device and an electrophoretic display device can be formed on the flexible substrate.

Next, the flexible display device is completed by peeling the flexible substrate on which the display elements are formed from the carrier substrate (S106). Peeling of the flexible substrate can be accomplished by irradiating a laser to the sacrificial layer of the flexible substrate. As the laser is irradiated, hydrogen is generated in the sacrificial layer, and the adhesion of the sacrificial layer is reduced by this hydrogen, causing the flexible substrate to peel off from the carrier substrate.

FIGS. 5A to 5D are plan views showing the actual manufacturing method of the display device according to the present invention, and FIGS. 6A to 6D are cross-sectional views showing the actual manufacturing method of the display device according to the present invention. The manufacturing of the present invention can be performed with reference to these drawings. The method is explained in more detail.

First, as shown in FIGS. 5A and 6A, after preparing the carrier substrate 180, a sacrificial layer 185 is formed over the entire carrier substrate 180. The carrier substrate 180 may be made of glass or a metal plate, but is not limited thereto and may be made of various materials. The sacrificial layer 185 can be formed by laminating amorphous silicon using a CVD (Chemical Vapor Deposition) method, but is not limited thereto.

Subsequently, the polyimide solution is applied to the entire surface of the sacrificial layer 185 by various methods such as spin coating, screen coating, roll coating, dispensing, etc. to form a polyimide film. (110a) is formed.

Thereafter, as shown in FIGS. 5B and 6B, the polyimide film 110a is patterned through an exposure process and cured to form the flexible substrate 110 on the sacrificial layer 185.

At this time, the flexible substrate 110 may have a rectangular shape with rounded corners. Patterning of the polyimide film 110a is performed through an exposure process, and the photomask used in the exposure process can be formed into various shapes. Therefore, by configuring the transmission area (or blocking area) of the photomask in a rounded rectangular shape, the flexible substrate 110 can be formed in a rectangular shape with rounded corners.

When forming a display device into a rounded rectangular shape by cutting and grinding the carrier substrate 180 to which the polyimide film 110a is attached, a mechanical cutting tool such as a cutting device must be used, so the shape with rounded corners is required. It was extremely difficult to form, and even when processed into a round shape, it was impossible to form a round with a perfect curve.

On the other hand, in the present invention, the flexible substrate 110 of a desired shape is formed by cutting the photomask, so that a perfect round shape, etc. can be easily created.

In addition, in the present invention, a bending area B is formed by forming a plurality of through holes 162 with a fine width in the bending area of the flexible substrate 110 through an exposure process of the polyimide film 110a. Such fine-width through-holes 162 cannot be manufactured through a mechanical cutting process, but in the present invention, a fine-width transmission area (or blocking area) corresponding to the through-hole can be easily manufactured in the photomask, It is possible to manufacture a through hole 162 of a desired width.

Meanwhile, in the drawing, the flexible substrate 110 is simply formed in a square shape with rounded corners, but in the present invention, the flexible substrate 110 of various shapes can be manufactured. For example, the flexible substrate 110 can be manufactured in various shapes such as circular, oval, or ring shapes.

It is impossible to form the flexible substrate into various shapes such as a circular shape, an oval shape, or a ring shape by cutting the carrier substrate and the flexible substrate together using a mechanical cutting tool such as a cutting device. In addition, it is also impossible to cut the carrier substrate and the flexible substrate together using an optical mechanism such as a laser to form the flexible substrate into various shapes such as a circular shape, an oval shape, or a ring shape.

However, in the present invention, it is possible to easily manufacture flexible substrates of various shapes as described above by cutting the photomask used in the exposure process into various shapes.

As described above, after forming the flexible substrate 110, as shown in FIGS. 5C and 6C, an organic electroluminescence display having a structure as shown in FIG. 2 is displayed in the display area (AA) of the flexible substrate 110. The device 101 is formed and various signal wires 148 as shown in FIG. 3 are formed between the through holes 162 of the pad area NA.

At this time, display elements of various structures, such as liquid crystal display elements or electrophoretic display elements, may be formed in the display area AA of the flexible substrate 110.

Next, as shown in FIGS. 5D and 6D, a laser is irradiated to the sacrificial layer 185 to peel the flexible substrate 110 on which the display element 101 is formed from the carrier substrate 180 to complete the display device. .

Although not shown in the drawing, an FPC on which a data driver is mounted is attached to the pad area (NA) of the peeled flexible substrate 110, and the pad area (NA) is folded along the bending area (B) to form a part of the display device. It is located on the back of the flexible substrate 110.

As described above, in the present invention, a plurality of through holes can be formed in the flexible substrate 110 by applying a polyimide solution on a carrier substrate and patterning it through an exposure process. Accordingly, by forming a bending area including a plurality of through holes in the flexible display device, the folded portion can be placed on the back of the flexible display device, thereby reducing the bezel of the display device.

Although many details are described in detail in the foregoing description, this should be interpreted as an example of a preferred embodiment rather than limiting the scope of the invention. Therefore, the invention should not be determined by the described embodiments, but by the scope of the patent claims and their equivalents.

100: display device 101: display element
110: Flexible board 148: Signal wiring
162: Through hole 180: Carrier substrate
185: Sacrificial layer B: Bending area

Claims (11)

A flexible substrate including a display area and a pad area;
a plurality of through holes provided in the pad area to form a bending area;
a display element formed in the display area; and
It consists of a plurality of signal wires disposed between through holes in the bending area and connected to the display element,
A display device in which the through hole extends perpendicular to a line in contact with the flexible substrate. The display device of claim 1, wherein the flexible substrate has a round shape. The display device of claim 1, wherein the bending area is folded toward the back of the flexible substrate. The display device of claim 1, wherein the display device includes an organic electroluminescent display device, a liquid crystal display device, or an electrophoretic display device. The display device of claim 1, wherein the flexible substrate is made of a polyimide-based plastic material. The display device of claim 1, wherein the folded area in the bending area is disposed on a rear surface of the flexible substrate. Forming a sacrificial layer on a carrier substrate;
forming a polyimide film by applying a polyimide solution to the entire surface of the sacrificial layer;
patterning the polyimide film to form a flexible substrate including a display area, a dummy area, and a plurality of through holes formed in the dummy area;
forming a display element in the display area and forming a plurality of signal wires between through holes in the dummy area; and
It consists of peeling the flexible substrate from the carrier substrate,
A display device manufacturing method wherein the through hole extends perpendicular to a line in contact with the flexible substrate. The method of claim 7, wherein the step of patterning the polyimide layer includes patterning the polyimide into a desired shape through an exposure process using a photomask. The method of claim 7, wherein peeling off the flexible substrate includes irradiating a laser to a sacrificial layer. The method of claim 7, wherein forming the display device includes forming an organic electroluminescent display device, a liquid crystal display device, or an electrophoretic display device. The display device of claim 1, wherein the through hole has a rectangular shape extending perpendicular to a line in contact with the flexible substrate.

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