KR102565140B1 - Plastic substrate and Display device including the same - Google Patents

Abstract

The present invention provides a plastic substrate having a structure in which a corrugated core sheet is interposed between base sheets and a display device including the same.
The plastic substrate of the present invention has a low coefficient of thermal expansion and high rigidity, so that a manufacturing process of a display device can be performed without a carrier substrate. Accordingly, the manufacturing process of the display device is simplified, the manufacturing cost is reduced, and the display device is prevented from being damaged, thereby improving the manufacturing yield of the display device.

Description

Plastic substrate and display device including the same

The present invention relates to a display device, and more particularly, to a plastic substrate having high rigidity and capable of manufacturing a display device without a carrier substrate and a display device including the same.

As society entered the information age in earnest, the display field, which processes and displays large amounts of information, has developed rapidly. Various flat panel display devices such as light emitting display device (OLED) have been developed and are in the spotlight.

For example, a liquid crystal display device includes, as essential components, a liquid crystal panel including an upper substrate and a lower substrate bonded to each other with a liquid crystal layer including liquid crystal molecules interposed therebetween. The liquid crystal layer is driven to display an image.

In addition, the organic light emitting display device includes, as an essential component, a light emitting diode including an anode and a cathode facing each other with an organic light emitting layer interposed therebetween, and the light emitting diode is formed on a substrate. In an organic light emitting display device, holes and electrons injected from an anode and a cathode are combined in an organic light emitting layer to emit light, thereby displaying an image.

Meanwhile, recently, demand for a flexible display device using a flexible substrate such as a plastic substrate has increased. Since the flexible display device can be carried in a folded state and displays an image in an unfolded state, it has the advantage of being easy to carry while being able to display a large screen.

However, in manufacturing such a flexible display device, since a plastic substrate used to have a flexible property has low rigidity, it is difficult to apply it to conventional display device manufacturing equipment for processing a glass substrate.

To overcome this problem, a process is performed by attaching a plastic substrate to one surface of a carrier substrate such as a glass substrate, and after the process is completed, the plastic substrate is released from the carrier substrate to manufacture a display device.

1A to 1C are schematic cross-sectional views illustrating a manufacturing process of a conventional display device using a plastic substrate.

As shown in Figure 1a, an ablation layer (ablation layer, 30) is formed on a carrier substrate 10 made of a glass material capable of transmitting a laser beam. For example, the ablation layer may be made of hydrogenated amorphous silicon (a-Si:H).

Next, a plastic substrate 20 is formed by coating a polymer material, for example, polyimide, on the laser ablation layer 30 .

As shown in FIG. 1B , a display element 40 is formed on the plastic substrate 20 .

For example, in the case of an organic light emitting diode display, the display element 40 may include a thin film transistor and a light emitting diode.

Next, as shown in FIG. 1C , the plastic substrate 20 is detached from the carrier substrate 10 by irradiating a laser beam on the rear surface of the carrier substrate 10 . When the ablation layer 30 is irradiated with a laser beam, hydrogen gas is discharged from the hydrogenated amorphous silicon (a-Si:H), whereby the adhesive force between the plastic substrate 20 and the ablation layer 30 is weakened. do. Thereafter, the plastic substrate 20 is separated through a vacuum adsorption process.

For example, since polyimide, which is a material of the plastic substrate 20, has poor adhesion to the carrier substrate 10 made of glass, an ablation layer ( 30) is required.

In addition, the ablation layer 30 is also required to detach the plastic substrate 20 from the carrier substrate 10 after the display device manufacturing process.

A display device including such a plastic substrate 20 includes a process of forming the ablation layer 30 and the plastic substrate 20 on the carrier substrate 10, and the carrier substrate 10 and the carrier substrate 10 after forming the display element. A process of separating the plastic substrate 20 is required, which complicates the manufacturing process of the display device.

In addition, damage to the plastic substrate 20 and/or the display device 40 occurs due to the vacuum adsorption process for separating the plastic substrate 20 .

The present invention, in a display device using a plastic substrate, is intended to solve the problem that the manufacturing process of the display device is complicated by the manufacturing process requiring a carrier substrate and damage that may occur to the plastic substrate and/or the display element.

In order to achieve the above object, a plastic substrate according to the present invention includes first and second base sheets facing each other, and a first core sheet positioned between the first and second base sheets and having a corrugated shape. do.

In addition, in the plastic substrate of the present invention, a first groove is formed on the upper surface of the first base sheet, and a second groove is formed on the lower surface of the second base sheet, and each of the first and second grooves has First and second adhesives may be filled, and the first core sheet may be attached to the first and second base sheets through the first and second adhesives.

In addition, the present invention provides a display device having the plastic substrate described above.

The plastic substrate according to the present invention includes a corrugated core sheet interposed between base sheets, and has a low coefficient of thermal expansion and high rigidity.

Therefore, since a flexible display device using a plastic substrate can be manufactured without a carrier substrate, the manufacturing process of the display device can be simplified and damage to the display device can be minimized.

In addition, reliability and durability of the plastic substrate may be improved by fixing the core by forming grooves filled with an adhesive on the inner surfaces of the upper and lower substrates.

In addition, the plastic substrate according to the present invention has a structure in which a first sub-substrate having a core having a wave shape in a first direction and a second sub-substrate having a wave shape in a second direction perpendicular to the first direction are stacked. , the rigidity of the plastic substrate can be further increased.

1A to 1C are schematic cross-sectional views illustrating a manufacturing process of a conventional display device using a plastic substrate.
2A and 2B are schematic cross-sectional and perspective views of a plastic substrate according to a first embodiment of the present invention, respectively.
3 is a schematic cross-sectional view of a plastic substrate according to a second embodiment of the present invention.
4 is a schematic cross-sectional view of a plastic substrate according to a third embodiment of the present invention.
5 is a schematic cross-sectional view of a plastic substrate according to a fourth embodiment of the present invention.
6 is a schematic cross-sectional view of a plastic substrate according to a fifth embodiment of the present invention.
7 is a schematic cross-sectional view of a display device according to a sixth embodiment of the present invention.
8 is a schematic cross-sectional view of a display device according to a seventh embodiment of the present invention.

The present invention provides a plastic substrate including first and second base sheets facing each other, and a first core sheet positioned between the first and second base sheets and having a wavy shape.

In the plastic substrate of the present invention, the first core sheet includes peaks and valleys, and the height of the peaks is equal to the thickness of each of the first and second base sheets.

In the plastic substrate of the present invention, the first core sheet and the first and second base sheets have the same modulus value.

In the plastic substrate of the present invention, the first core sheet has a higher modulus value than the first and second base sheets.

In the plastic substrate of the present invention, the first core sheet includes peaks and valleys, and the height of the peak is greater than the thickness of each of the first and second base sheets.

In the plastic substrate of the present invention, the first core sheet has a smaller modulus value than the first and second base sheets.

In the plastic substrate of the present invention, the first core sheet includes peaks and valleys, and the height of the peak is smaller than the thickness of each of the first and second base sheets.

In the plastic substrate of the present invention, a first groove is formed on an upper surface of the first base sheet, a second groove is formed on a lower surface of the second base sheet, and each of the first and second grooves has a first groove. First and second adhesives are filled, and the first core sheet is attached to the first and second base sheets through the first and second adhesives.

The plastic substrate of the present invention includes a third base sheet positioned under the first base sheet and a second core sheet positioned between the first and third base sheets and having a wavy shape, wherein the first core sheet The extension direction of the sheet and the extension direction of the second core sheet are perpendicular to each other.

From another point of view, the present invention provides first and second base sheets facing each other, a plurality of first contact points located between the first and second base sheets and in contact with the first base sheet, and the second base sheet It provides a plastic substrate including a first core sheet having a plurality of second contact points in contact with.

In the plastic substrate of the present invention, an air layer is provided between the adjacent first contact points or the adjacent second contact points.

In the plastic substrate of the present invention, the first core sheet and the first and second base sheets have the same modulus value.

In the plastic substrate of the present invention, the first core sheet has a higher modulus value than the first and second base sheets, and extends from one side of the first base sheet in contact with the first core sheet to the second contact point. The vertical distance is greater than the thickness of each of the first and second base sheets.

In the plastic substrate of the present invention, the first core sheet has a lower modulus value than the first and second base sheets, and extends from one surface of the first base sheet in contact with the first core sheet to the second contact point. The vertical distance is smaller than the thickness of each of the first and second base sheets.

In another aspect, the present invention provides a display device including the aforementioned plastic substrate, a light emitting diode positioned on the plastic substrate, and a thin film transistor positioned between the plastic substrate and the light emitting diode and connected to the light emitting diode. do.

In another aspect, the present invention provides first and second substrates facing each other, a pixel electrode positioned on the first substrate, a common electrode positioned on any one of the first and second substrates, and the first substrate. A display device includes a liquid crystal layer positioned between first and second substrates, and at least one of the first and second substrates is the aforementioned plastic substrate.

Hereinafter, preferred embodiments according to the present invention will be described with reference to the drawings.

2A and 2B are schematic cross-sectional and perspective views of a plastic substrate according to a first embodiment of the present invention, respectively.

As shown in FIGS. 2A and 2B, the plastic substrate 100 according to the first embodiment of the present invention includes a core layer 110 including a core sheet 112 having a wave shape, It includes first and second base sheets 120 and 130 positioned below and above the core sheet 112 , respectively. That is, the corrugated core sheet 112 is interposed between the first and second base sheets 120 and 130 and contacts them, respectively.

Each of the core sheet 112 and the first and second base sheets 120 and 130 may be made of polyimide (PI).

The core sheet 112 has a shape in which peaks 110a and valleys 110b are repeated, that is, a waveform shape. The valleys 110b of the core sheet 112 may contact the first base sheet 120 and the peaks 110a of the core sheet 112 may contact the second base sheet 130 . For example, the valleys 110b and peaks 110a of the core sheet 112 are attached to the first and second base sheets 120 and 130 by an adhesive (not shown), respectively.

In other words, the plastic substrate 100 of the present invention includes first and second base sheets 120 and 130 facing each other and a core sheet 112 positioned between the first and second base sheets 120 and 130. Including, the plurality of valleys 110b of the core sheet 112 come into contact with or contact the first base sheet 120 as a plurality of first contact points, and the plurality of peaks 110a of the core sheet 112 As a plurality of second contact points, they contact or come into contact with the second substrate sheet 130 .

The peaks 110a and valleys 110b of the core sheet 112 may be arranged at the same interval and at the same height and depth. The peaks 110a and valleys 110b of the core sheet 112 extend in one direction.

The space between the peak 110a of the core sheet 112 and the first base sheet 120 and the space between the valley 110b of the core sheet 112 and the second base sheet 130 are filled with air to layer 110.

That is, an air layer is formed between adjacent valleys 110b (first contact point) and adjacent peaks 110a (second contact point) of the core sheet 112 .

Each of the first and second base sheets 120 and 130 has a flat outer surface. Accordingly, the plastic substrate 100 has flat lower and upper surfaces.

The core sheet 112 and each of the first and second base sheets 120 and 130 have substantially the same modulus value. In addition, the first thickness t1 of the core layer 110, that is, the height of the peak 110a of the core sheet 112 or the depth of the valley 110b of the core sheet 112 is determined by the first and second substrate sheets. It is substantially equal to the second and third thicknesses t2 and t3 of (120 and 130). For example, each of the first to third thicknesses t1 , t2 , and t3 may be about 70 μm to 150 μm.

In other words, the core layer 110 including the corrugated core sheet 112 having a fourth thickness t4 smaller than the first thickness t1 is between the first and second base sheets 120 and 130. interposed therebetween to form the plastic substrate 100, and the distance between the first and second base sheets 120 and 130 is greater than the fourth thickness t4 of the corrugated core sheet 122. For example, the fourth thickness t4 may be about 10 to 20 μm.

As such, the plastic substrate 100 of the present invention has excellent rigidity (high modulus value) and low thermal expansion coefficient. Accordingly, display elements of a display device may be formed on the plastic substrate 100 without a carrier substrate.

3 is a schematic cross-sectional view of a plastic substrate according to a second embodiment of the present invention.

As shown in FIG. 3, the plastic substrate 200 according to the second embodiment of the present invention includes a first substrate sheet 220 having a first groove 222 on an inner surface, and a second groove ( 232), the first and second adhesives 224 and 234 positioned in the first and second grooves 222 and 232, respectively, and the first and second adhesives ( 224 and 234 and a core layer 210 interposed between the first and second base sheets 220 and 230 and includes a core sheet 212 having a wave shape in contact with the first and second base sheets 220 and 230 .

Each of the core sheet 212 and the first and second base sheets 220 and 230 may be made of polyimide (PI).

The core sheet 212 has a shape in which peaks 210a and valleys 210b are repeated, that is, a wave shape. The valleys 210b of the core sheet 212 correspond to the first grooves 222 of the first base sheet 220, and the peaks 210a of the core sheet 212 correspond to the second base sheet 230. ) corresponds to the second groove 232. Accordingly, the valleys 210b of the core sheet 212 are attached to the first base sheet 220 by the first adhesive 224 positioned in the first groove 222, and the core sheet 212 The acid 210a of is attached to the second substrate sheet 230 by a second adhesive 234 located in the second groove 232 .

Each of the first and second adhesives 224 and 234 may be a thermosetting adhesive such as an epoxy-based, silane-based, or urethane-based adhesive.

The peaks 210a and valleys 210b of the core sheet 212 may be arranged at the same interval and at the same height and depth. The peaks 210a and valleys 210b of the core sheet 212 extend in one direction.

The space between the peak 210a of the core sheet 212 and the first base sheet 220 and the space between the valley 210b of the core sheet 212 and the second base sheet 230 are filled with air to layer 210.

Each of the first and second base sheets 220 and 230 has a flat outer surface. Thus, the plastic substrate 200 has flat lower and upper surfaces.

The core sheet 212 and each of the first and second base sheets 220 and 230 have substantially the same modulus value. In addition, the first thickness t1 of the core layer 210, that is, the height of the peak 210a of the core sheet 212 or the depth of the valley 210b of the core sheet 212 is determined by the first and second substrate sheets. It is substantially equal to the second and third thicknesses t2 and t3 of (220 and 230). For example, each of the first to third thicknesses t1 , t2 , and t3 may be about 70 μm to 150 μm.

In other words, the core layer 210 including the corrugated core sheet 212 having a fourth thickness t4 smaller than the first thickness t1 is between the first and second base sheets 220 and 230. interposed therebetween to form the plastic substrate 200, and the distance between the first and second base sheets 220 and 230 is greater than the fourth thickness t4 of the corrugated core sheet 212. For example, the fourth thickness t4 may be about 10 to 20 μm.

As such, the plastic substrate 200 of the present invention has excellent rigidity (high modulus value) and low thermal expansion coefficient. Accordingly, display elements of a display device may be formed on the plastic substrate 200 without a carrier substrate.

The properties of the glass substrate, the single PI substrate and the plastic substrate according to the second embodiment of the present invention were measured and are listed in Table 1 below.

[Table 1]

As shown in Table 1, the plastic substrate (experimental example) of the present invention has a smaller thickness than the glass substrate and has excellent stiffness (high modulus value) and low thermal expansion coefficient. In addition, thermal stability is secured by having a thermal decomposition temperature (Td 1%) applicable to the display device manufacturing process.

In addition, from the results of measuring the plane compressive strength, it can be seen that the core layer of the plastic substrate is not damaged by the external pressure.

That is, the plane compressive strength was measured while passing the substrate between the roller and the stage and increasing the load applied to the roller. In the case of the glass substrate, cracks occurred when a load of 8 kgf was applied, but the plastic of the present invention had a load of 10 kgf No damage occurred under load.

On the other hand, rigidity can be improved by increasing the thickness of a single substrate made of polyimide. However, in order to manufacture a thick polyimide substrate, when a varnish-like polyimide resin is thickly coated and then a curing process is performed, the surface layer is thickly and hardened. Therefore, the polyimide substrate has a large difference in physical properties depending on the thickness. That is, it is difficult to manufacture a thick polyimide substrate having uniform physical properties, and as shown in Table 1, the thermal expansion coefficient greatly increases, so there is a limit to its application as a substrate for a display device.

4 is a schematic cross-sectional view of a plastic substrate according to a third embodiment of the present invention.

As shown in FIG. 4, the plastic substrate 300 according to the third embodiment of the present invention includes a first substrate sheet 320 having a first groove 322 on an inner surface, and a second groove ( 332), the first and second adhesives 324 and 334 positioned in the first and second grooves 322 and 332, respectively, and the first and second adhesives ( 324 and 334 and a core layer 310 interposed between the first and second substrate sheets 320 and 330 and includes a core sheet 312 having a wave shape in contact with the first and second substrate sheets 320 and 330 .

Each of the core sheet 312 and the first and second base sheets 320 and 330 may be made of polyimide (PI).

The core sheet 312 has a shape in which peaks 310a and valleys 310b are repeated, that is, a wave shape.

The peaks 310a and valleys 310b of the core sheet 312 may be arranged at the same interval and at the same height and depth. The peaks 310a and valleys 310b of the core sheet 312 extend in one direction.

The valleys 310b of the core sheet 312 correspond to the first grooves 322 of the first base sheet 320, and the peaks 310a of the core sheet 312 correspond to the second base sheet 330. ) corresponds to the second groove 332. Accordingly, the valleys 310b of the core sheet 312 are attached to the first base sheet 320 by the first adhesive 324 positioned in the first groove 322, and the core sheet 312 The acid 310a of is attached to the second substrate sheet 330 by a second adhesive 334 located in the second groove 332 .

Each of the first and second grooves 322 and 332 are formed parallel to the extension direction of the core sheet 312 and are alternately positioned.

Each of the first and second adhesives 324 and 334 may be an epoxy-based, silane-based, or urethane-based thermosetting adhesive.

The space between the peak 310a of the core sheet 312 and the first base sheet 320 and the space between the valley 310b of the core sheet 312 and the second base sheet 330 are filled with air to layer 310.

Each of the first and second base sheets 320 and 330 has a flat outer surface. Accordingly, the plastic substrate 300 has flat lower and upper surfaces.

The core sheet 312 has a smaller modulus value than the first and second base sheets 320 and 330, respectively, and has a first thickness t1 of the core layer 310, that is, the core sheet 312 The height of the peak 310a of ) or the depth of the valley 310b of the core sheet 312 is smaller than the second and third thicknesses t2 and t3 of the first and second base sheets 320 and 330 . For example, the first thickness t1 may be about 50 to 100 μm, and each of the second and third thicknesses t1, t2, and t3 may be about 70 to 150 μm.

In other words, the plastic substrate 300 of the present invention includes first and second base sheets 320 and 330 facing each other and a core sheet 312 positioned between the first and second base sheets 320 and 330. Including, the plurality of valleys 310b of the core sheet 312 come into contact with or contact the first base sheet 320 as a plurality of first contact points, and the plurality of peaks 310a of the core sheet 312 As a plurality of second contact points, they contact or come into contact with the second substrate sheet 330 .

At this time, the first core sheet 312 has a smaller modulus value than the first and second base sheets 320 and 330, and the first base sheet 320 in contact with the first core sheet 312 A vertical distance from one surface to the mountain 310a (second contact point) is smaller than the respective thicknesses of the first and second base sheets 320 and 330 .

When the modulus value of the core sheet 312 is small, when the thickness t1 of the core layer 310, that is, the height of the peak 310a of the core sheet 312 is increased, the core sheet 312 is It can be deformed by (external force). Therefore, in the third embodiment of the present invention, the thickness t1 of the core layer 310 is reduced, and thus the overall thickness of the plastic substrate 300 can be reduced.

The distance between the first and second base sheets 320 and 330 is greater than the fourth thickness t4 of the corrugated core sheet 312 . For example, the fourth thickness t4 may be about 10 to 20 μm.

A core layer 310 including a corrugated core sheet 312 having a fourth thickness t4 smaller than the first thickness t1 is interposed between the first and second base sheets 320 and 330, It forms the plastic substrate 300.

As such, the plastic substrate 300 of the present invention has excellent rigidity (high modulus value) and low thermal expansion coefficient. Accordingly, display elements of the display device may be formed on the plastic substrate 300 without a carrier substrate.

In addition, the corrugated core sheet 312 has a smaller modulus value than the first and second base sheets 320 and 330, and the thickness of the core layer 310 is smaller than that of the first and second base sheets 320 and 330. , the overall thickness of the plastic substrate 300 can be reduced. Accordingly, a thin display device including the plastic substrate 300 of the present invention can be provided.

5 is a schematic cross-sectional view of a plastic substrate according to a fourth embodiment of the present invention.

As shown in FIG. 5, the plastic substrate 400 according to the fourth embodiment of the present invention includes a first substrate sheet 420 having a first groove 422 on an inner surface, and a second groove ( 432), the first and second adhesives 424 and 434 positioned in the first and second grooves 422 and 432, respectively, and the first and second adhesives ( 424 and 434 and a core layer 410 interposed between the first and second base sheets 420 and 430 and includes a core sheet 412 having a wave shape in contact with the first and second base sheets 420 and 430 .

Each of the core sheet 412 and the first and second base sheets 420 and 430 may be made of polyimide (PI).

The core sheet 412 has a shape in which peaks 410a and valleys 410b are repeated, that is, a wave shape. The peaks 410a and valleys 410b of the core sheet 412 may be arranged at the same interval and at the same height and depth. The peaks 410a and valleys 410b of the core sheet 412 extend in one direction.

The valleys 410b of the core sheet 412 correspond to the first grooves 422 of the first base sheet 420, and the peaks 410a of the core sheet 412 correspond to the second base sheet 430. ) corresponds to the second groove 432. Therefore, the valleys 410b of the core sheet 412 are attached to the first base sheet 420 by the first adhesive 424 positioned in the first groove 422, and the core sheet 412 The acid 410a is attached to the second substrate sheet 430 by a second adhesive 434 located in the second groove 432 .

Each of the first and second grooves 422 and 432 are formed parallel to the extension direction of the core sheet 412 and are alternately positioned.

Each of the first and second adhesives 424 and 434 may be a thermosetting adhesive such as an epoxy-based, silane-based, or urethane-based adhesive.

The space between the crest 410a of the core sheet 412 and the first base sheet 420 and the space between the valley 410b of the core sheet 412 and the second base sheet 430 are filled with air so that the core sheet 412 is filled with air. layer 410.

Each of the first and second base sheets 420 and 430 has a flat outer surface. Accordingly, the plastic substrate 400 has flat lower and upper surfaces.

The core sheet 412 has a higher modulus value than each of the first and second base sheets 420 and 430 . At this time, the first thickness t1 of the core layer 410, that is, the height of the peak 410a of the core sheet 412 or the depth of the valley 410b of the core sheet 412 is determined by the first and second substrate sheets. It may be greater than the second and third thicknesses t2 and t3 of (420 and 430). For example, the first thickness t1 may be about 100 to 200 μm, and each of the second and third thicknesses t1, t2, and t3 may be about 70 to 150 μm.

In other words, the plastic substrate 400 of the present invention includes first and second base sheets 420 and 430 facing each other and a core sheet 412 positioned between the first and second base sheets 420 and 430. Including, the plurality of valleys 410b of the core sheet 412 come into contact or contact with the first base sheet 420 as a plurality of first contact points, and the plurality of peaks 410a of the core sheet 412 As a plurality of second contact points, they contact or come into contact with the second substrate sheet 430 .

At this time, the first core sheet 412 has a smaller modulus value than the first and second base sheets 420 and 430, and the first base sheet 420 in contact with the first core sheet 412 A vertical distance from one surface to the mountain 410a (second contact point) is smaller than the respective thicknesses of the first and second base sheets 420 and 430 .

When the core sheet 412 has a large modulus value, even if the height of the peak 410a increases, the problem that the core sheet 412 is deformed by pressure does not occur, and the core sheet 412 having a large modulus value As a result, the entire rigidity of the plastic substrate 400 is increased.

That is, in the plastic substrate 400 according to the fourth embodiment of the present invention, the core sheet 412 is formed of a material having a relatively high modulus value, and the thickness of the core layer 410 including the core sheet 412 is increased. to improve the rigidity of the plastic substrate 400.

However, when the core sheet 412 has a higher modulus than the first and second base sheets 420 and 430, the first thickness t1 and the first And the relationship between the second and third thicknesses t2 and t3 of the second base sheets 420 and 430 is not limited. That is, the first thickness t1 of the core layer 410 may be equal to or smaller than the second and third thicknesses t2 and t3 of the first and second base sheets 420 and 430 .

The distance between the first and second base sheets 420 and 430 is greater than the fourth thickness t4 of the corrugated core sheet 412 . For example, the fourth thickness t4 may be about 10 to 20 μm.

A core layer 410 including a corrugated core sheet 412 having a fourth thickness t4 smaller than the first thickness t1 is interposed between the first and second base sheets 420 and 430, It forms the plastic substrate 400.

As such, the plastic substrate 400 of the present invention has excellent rigidity (high modulus value) and low coefficient of thermal expansion. Accordingly, display elements of the display device may be formed on the plastic substrate 400 without a carrier substrate.

In addition, the corrugated core sheet 412 can have a relatively large modulus value to have a corrugated shape without damage, and the thickness of the core layer 410 including the core sheet 412 is increased to form a plastic substrate 400. stiffness is further increased.

6 is a schematic cross-sectional view of a plastic substrate according to a fifth embodiment of the present invention.

As shown in FIG. 6, the plastic substrate 500 according to the fifth embodiment of the present invention includes a first core layer 510 including a first core sheet 512 having a wave shape, and A first sub-substrate 501 including first and second substrate sheets 520 and 530 respectively located below and above the core sheet 512, and a second core sheet 542 having a wave shape. ) and a second core layer 540 positioned under the first base sheet 520, and a third base sheet 550 positioned under the second core sheet 542. A sub-substrate 502 is included.

In FIG. 6 , the first sub-substrate 501 and the second sub-substrate 502 share a lower substrate sheet and an upper substrate sheet. Unlike this, the second sub-substrate 502 includes a fourth sub-substrate positioned between the first sub-substrate 520 and the second core layer 540, and the first sub-substrate 520 and The fourth sub-substrate may be attached through an adhesive layer.

The peaks and valleys of the first core sheet 512 may be arranged at the same interval and at the same height and depth. The peaks and valleys of the first core sheet 512 extend in the first direction. In addition, peaks and valleys of the second core sheet 542 may be arranged at the same interval and at the same height and depth. The peaks and valleys of the second core sheet 542 extend in a second direction perpendicular to the first direction.

That is, the plastic substrate 500 according to the fifth embodiment of the present invention has a structure in which the plastic substrates of any one of the first to fourth embodiments of the present invention are stacked so that the core sheets are vertically arranged.

The space between the peak of the first core sheet 512 and the first base sheet 520 and the space between the valley of the first core sheet 512 and the second base sheet 530 are filled with air to form a first core layer. (510). In addition, the space between the peak of the second core sheet 542 and the first base sheet 520 and the space between the valley of the second core sheet 542 and the third base sheet 550 are filled with air to It forms the core layer 540 .

Each of the second and third base sheets 530 and 550 has a flat outer surface. Accordingly, the plastic substrate 500 has flat lower and upper surfaces.

The first core sheet 512 may have substantially the same modulus value as each of the first and second base sheets 520 and 530 . In addition, the thickness of the first core layer 510, that is, the height of the crest of the first core sheet 512 or the depth of the valley of the first core sheet 512 is determined by the first and second base sheets 520 and 530. It may be substantially the same as each thickness. Also, the second core sheet 542 may have substantially the same modulus value as that of the first and third base sheets 520 and 550 , respectively. In addition, the thickness of the second core layer 540, that is, the height of the crest of the second core sheet 542 or the depth of the valley of the second core sheet 542 is determined by the first and third base sheets 520 and 550. It may be substantially the same as each thickness.

Alternatively, each of the first and second core sheets 512 and 542 has a higher modulus value than each of the first to third base sheets 520, 530, and 550, and The thickness of each of the core layers 510 and 540, for example, the height of the peak of the first core sheet 512 or the depth of the valley of the first core sheet 512, is determined by the first to third base sheets 520, 530, 550) may be smaller than each thickness.

In addition, each of the first and second core sheets 512 and 542 has a smaller modulus value than each of the first to third base sheets 520, 530, and 550, and the first and second core sheets 512 and 542 have a lower modulus value. The thickness of each of the layers 510 and 540, for example, the height of a peak of the first core sheet 512 or the depth of a valley of the first core sheet 512, is determined by the first to third base sheets 520, 530, and 550 ) may be greater than the respective thickness.

The distance between the first and second base sheets 420 and 430 and the distance between the first and third base sheets 520 and 550 are respectively the first and second core sheets 512 and 542 having a corrugated shape. greater than the thickness.

Although not shown, first and second grooves are formed on the upper surface of the first base sheet 520 and the lower surface of the second base sheet 530, and the first and second grooves are filled with an adhesive. , peaks and valleys of the first core sheet 512 may be attached to the first and second base sheets 520 and 530 through the adhesive. In addition, third and fourth grooves are formed on the lower surface of the first base sheet 520 and the upper surface of the third base sheet 550, and the third and fourth grooves are filled with an adhesive. Peaks and valleys of the second core sheet 542 may be attached to the first and third base sheets 520 and 550 through the adhesive.

Each of the first and second grooves is formed parallel to the extending direction of the first core sheet 512 and is alternately positioned. In addition, each of the third and fourth grooves is formed parallel to the extension direction of the second core sheet 542 and is alternately positioned. At this time, the first groove and the third groove cross each other perpendicularly.

As such, the plastic substrate 500 of the present invention has excellent rigidity (high modulus value). Accordingly, display elements of the display device may be formed on the plastic substrate 500 without a carrier substrate.

Referring to FIG. 7 , the display device 600 is interposed between first and second plastic substrates 610 and 650 facing each other and the first and second plastic substrates 610 and 650, and liquid crystal molecules ( and a liquid crystal layer 660 including 662). That is, the display device 600 according to the sixth embodiment of the present invention is a liquid crystal display device.

At least one of the first and second plastic substrates 610 and 650 includes a core layer including a core sheet and base sheets attached to lower and upper portions of the core layer.

For example, referring to FIG. 3 , the first plastic substrate 610 includes a first substrate sheet 220 having a first groove 222 on an inner surface and a second groove 232 on an inner surface. The second substrate sheet 230, the first and second adhesives 224 and 234 positioned in the first and second grooves 222 and 232, respectively, and the first and second adhesives 224 and 234 It may include a core layer 210 interposed between the first and second substrate sheets 220 and 230 including a core sheet 212 having a wave shape in contact with the core sheet 212 .

A first buffer layer 620 is formed on the first plastic substrate 610 , and a thin film transistor Tr is formed on the first buffer layer 620 . The first buffer layer 620 may be omitted.

A gate electrode 622 is formed on the first buffer layer 620 , and a gate insulating layer 624 is formed covering the gate electrode 622 . In addition, a gate wire (not shown) connected to the gate electrode 622 is formed on the buffer layer 620 .

A semiconductor layer 626 is formed on the gate insulating layer 624 to correspond to the gate electrode 622 . The semiconductor layer 626 may be made of an oxide semiconductor material. Meanwhile, the semiconductor layer 626 may include an active layer made of amorphous silicon and an ohmic contact layer made of impurity amorphous silicon.

A source electrode 630 and a drain electrode 632 spaced apart from each other are formed on the semiconductor layer 626 . In addition, a data line (not shown) connected to the source electrode 630 intersects the gate line to define a pixel area.

The gate electrode 622, the semiconductor layer 626, the source electrode 630, and the drain electrode 632 constitute a thin film transistor Tr.

A protective layer 634 having a drain contact hole 636 exposing the drain electrode 632 is formed on the thin film transistor Tr.

On the protective layer 634, a pixel electrode 640 connected to the drain electrode 632 through the drain contact hole 636 and a common electrode 642 alternately arranged with the pixel electrode 640 are formed. is formed

A second buffer layer 652 is formed on the second plastic substrate 650, and on the second buffer layer 652, a black matrix covering non-display areas such as the thin film transistor Tr, the gate wiring, and the data wiring ( 654) is formed. In addition, a color filter layer 656 is formed corresponding to the pixel area. The second buffer layer 652 and the black matrix 654 may be omitted.

The first and second plastic substrates 610 and 650 are bonded with the liquid crystal layer 660 therebetween, and the liquid crystal layer ( The liquid crystal molecules 662 of 660 are driven. Meanwhile, the common electrode 642 may be formed on the second plastic substrate 650 .

Although not shown, an alignment layer may be formed on each of the first and second plastic substrates 610 and 650 in contact with the liquid crystal layer 660, and the first and second plastic substrates 610 and 650, respectively. Polarizers having transmission axes perpendicular to each other may be attached to the outside of the .

In addition, a backlight unit is disposed under the first plastic substrate 610 to supply light toward the first substrate 610 .

For example, the backlight unit includes a light guide plate positioned under the first plastic substrate 610, a light source positioned on at least one side of the light guide plate, a reflector positioned on a rear surface of the light guide plate, the light guide plate and the first light guide plate. An optical sheet positioned between the plastic substrates 610 may be included.

As described above, in the display device 600 according to the sixth embodiment of the present invention, at least one of the first and second plastic substrates 610 and 650 includes a core layer including a corrugated core sheet; Since the base sheet attached to the lower and upper portions of the core layer has high rigidity, the display device 600 can be manufactured without a carrier substrate.

Therefore, the manufacturing process of the display device 600 is simplified, manufacturing cost is reduced, and damage to the display device 600 is reduced, thereby increasing manufacturing yield.

Referring to FIG. 8 , the display device 700 includes a plastic substrate 710, a thin film transistor Tr positioned on the plastic substrate 710, and a thin film transistor positioned on the plastic substrate 710 ( and a light emitting diode (D) connected to Tr). That is, the display device 700 according to the seventh embodiment of the present invention is a light emitting diode display device.

The plastic substrate 710 includes a core layer including a core sheet and base sheets attached to lower and upper portions of the core layer.

For example, referring to FIG. 3 , the plastic substrate 710 includes a first substrate sheet 220 having a first groove 222 on an inner surface and a second substrate sheet 220 having a second groove 232 on an inner surface. Contact with the base sheet 230, the first and second adhesives 224 and 234 positioned in the first and second grooves 222 and 232, respectively, and the first and second adhesives 224 and 234 It may include a core sheet 212 having a wave shape, and a core layer 210 interposed between the first and second base sheets 220 and 230 .

A buffer layer 720 is formed on the plastic substrate 710 , and a thin film transistor Tr is formed on the buffer layer 720 . The buffer layer 720 may be omitted.

A semiconductor layer 722 is formed on the buffer layer 720 . The semiconductor layer 722 may be made of an oxide semiconductor material or polycrystalline silicon.

When the semiconductor layer 722 is made of an oxide semiconductor material, a light blocking pattern (not shown) may be formed under the semiconductor layer 722, and the light blocking pattern prevents light from entering the semiconductor layer 722. Thus, the semiconductor layer 722 is prevented from being deteriorated by light. Alternatively, the semiconductor layer 722 may be made of polycrystalline silicon, and in this case, both edges of the semiconductor layer 722 may be doped with impurities.

A gate insulating layer 724 made of an insulating material is formed on the semiconductor layer 722 . The gate insulating layer 724 may be made of an inorganic insulating material such as silicon oxide or silicon nitride.

A gate electrode 730 made of a conductive material such as metal is formed on the gate insulating layer 724 corresponding to the center of the semiconductor layer 722 .

In FIG. 8 , the gate insulating film 724 is formed on the entire surface of the plastic substrate 710 , but the gate insulating film 724 may be patterned in the same shape as the gate electrode 730 .

An interlayer insulating layer 732 made of an insulating material is formed on the gate electrode 730 . The interlayer insulating layer 732 may be formed of an inorganic insulating material such as silicon oxide or silicon nitride, or an organic insulating material such as benzocyclobutene or photo-acryl.

The interlayer insulating layer 732 has first and second contact holes 734 and 736 exposing both sides of the semiconductor layer 722 . The first and second contact holes 734 and 736 are spaced apart from the gate electrode 730 on both sides of the gate electrode 730 .

Here, the first and second contact holes 734 and 736 are also formed in the gate insulating layer 724 . Alternatively, when the gate insulating layer 724 is patterned in the same shape as the gate electrode 730 , the first and second contact holes 734 and 736 may be formed only in the interlayer insulating layer 732 .

A source electrode 740 and a drain electrode 742 made of a conductive material such as metal are formed on the interlayer insulating film 732 .

The source electrode 740 and the drain electrode 742 are spaced apart from each other with respect to the gate electrode 730, and both sides of the semiconductor layer 722 through the first and second contact holes 734 and 736, respectively. come into contact with

The semiconductor layer 722, the gate electrode 730, the source electrode 740, and the drain electrode 742 constitute the thin film transistor Tr, and the thin film transistor Tr is a driving element. ) function as

The thin film transistor Tr has a coplanar structure in which the gate electrode 730, the source electrode 742, and the drain electrode 744 are positioned on the semiconductor layer 720.

Alternatively, the thin film transistor Tr may have an inverted staggered structure in which a gate electrode is positioned below the semiconductor layer and a source electrode and a drain electrode are positioned above the semiconductor layer. In this case, the semiconductor layer may be made of amorphous silicon.

Although not shown, a gate line and a data line cross each other to define a pixel area, and a switching element connected to the gate line and the data line is further formed. The switching element is connected to the thin film transistor Tr, which is a driving element.

In addition, a power line is formed to be spaced apart in parallel with the data line or the data line, and a storage capacitor for maintaining a constant voltage of the gate electrode of the thin film transistor (Tr), which is a driving element, for one frame is further provided. can be configured.

A protective layer 750 having a drain contact hole 752 exposing the drain electrode 742 of the thin film transistor Tr is formed to cover the thin film transistor Tr.

On the protective layer 750, a first electrode 760 connected to the drain electrode 742 of the thin film transistor Tr through the drain contact hole 752 is formed separately for each pixel area. The first electrode 760 may be an anode and may be made of a conductive material having a relatively high work function value. For example, the first electrode 760 may be made of a transparent conductive material such as indium-tin-oxide (ITO) or indium-zinc-oxide (IZO). .

A reflective electrode or a reflective layer is formed above or below the first electrode 760 to increase light efficiency. For example, the reflective electrode or the reflective layer may be made of an aluminum-palladium-copper (APC) alloy. The first electrode 760 may have a triple layer structure of ITO/APC/ITO.

In addition, a bank layer 766 covering an edge of the first electrode 760 is formed on the passivation layer 750 . The bank layer 766 exposes the center of the first electrode 760 corresponding to the pixel area.

An emission layer 762 is formed on the first electrode 760 . The light emitting layer 762 may have a single layer structure of an emitting material layer made of a light emitting material. In addition, in order to increase the luminous efficiency, the light emitting layer 762 includes a hole injection layer, a hole transporting layer, a light emitting material layer, and an electron transporting layer (which are sequentially stacked on the first electrode 760). It may have a multilayer structure of an electron transporting layer and an electron injection layer.

The light emitting material layer may include an inorganic light emitting material such as quantum dots or an organic light emitting material.

A second electrode 764 is formed on the plastic substrate 710 on which the light emitting layer 762 is formed. The second electrode 764 is located on the front surface of the display area and is made of a conductive material having a relatively low work function value and can be used as a cathode. For example, the second electrode 764 may be formed of any one of aluminum (Al), magnesium (Mg), and an aluminum-magnesium alloy (AlMg).

The first electrode 760, the light emitting layer 762, and the second electrode 764 form a light emitting diode (D).

Although not shown, an encapsulation film may be formed on the second electrode 764 to prevent external moisture from penetrating into the light emitting diode D. The encapsulation film may have a stacked structure of a first inorganic insulating layer, an organic insulating layer, and a second inorganic insulating layer, but is not limited thereto. In addition, a polarizing plate (not shown) may be attached to the encapsulation film to reduce reflection of external light. For example, the polarizing plate may be a circular polarizing plate.

As described above, in the display device 700 according to the seventh embodiment of the present invention, the plastic substrate 710 includes a core layer including a corrugated core sheet and attached to the lower and upper portions of the core layer. Since it has high rigidity including the base sheet, the display device 700 can be manufactured without a carrier substrate.

Accordingly, the manufacturing process of the display device 700 is simplified, manufacturing cost is reduced, and damage to the display device 700 is reduced, thereby increasing manufacturing yield.

Although the above has been described with reference to preferred embodiments of the present invention, those skilled in the art may variously modify the present invention within the scope not departing from the technical spirit and scope of the present invention described in the claims below. And it will be understood that it can be changed.

100, 200, 300, 400, 500: plastic substrate 501, 502: sub substrate
110, 210, 310, 410, 510, 510: core layer
112, 212, 312, 412, 512, 512: core sheet
120, 130, 220, 230, 320, 330, 420, 430, 520, 530, 550: base sheet
222, 232, 322, 332, 422, 432: home
224, 234, 324, 334, 424, 434: adhesive 600, 700: display device

Claims (17)

first and second base sheets facing each other;
A first core sheet positioned between the first and second base sheets and having a corrugated shape,
A first groove is formed on an upper surface of the first base sheet, a second groove is formed on a lower surface of the second base sheet, and first and second adhesives are filled in each of the first and second grooves, ,
The first core sheet is attached to the first and second substrate sheets through the first and second adhesives.
According to claim 1,
The plastic substrate of claim 1 , wherein the first core sheet includes peaks and valleys, and heights of the peaks are equal to thicknesses of the first and second base sheets, respectively.
According to claim 2,
The plastic substrate of claim 1 , wherein the first core sheet and the first and second base sheets have the same modulus value.
According to claim 1,
The plastic substrate of claim 1 , wherein the first core sheet has a higher modulus value than the first and second base sheets.
According to claim 4,
The plastic substrate of claim 1 , wherein the first core sheet includes peaks and valleys, and heights of the peaks are greater than thicknesses of the first and second base sheets.
According to claim 1,
The plastic substrate of claim 1 , wherein the first core sheet has a smaller modulus value than the first and second base sheets.
According to claim 6,
The plastic substrate of claim 1 , wherein the first core sheet includes peaks and valleys, and heights of the peaks are smaller than thicknesses of the first and second base sheets.
delete According to claim 1,
a third base sheet positioned under the first base sheet;
A second core sheet positioned between the first and third base sheets and having a corrugated shape,
The plastic substrate of claim 1 , wherein an extending direction of the first core sheet and an extending direction of the second core sheet are perpendicular to each other.
first and second base sheets facing each other;
A first core sheet disposed between the first and second base sheets and having a plurality of first contact points in contact with the first base sheet and a plurality of second contacts in contact with the second base sheet,
A plurality of first grooves are formed on the upper surface of the first base sheet to correspond to the plurality of first contact points, and a plurality of second grooves are formed on the lower surface of the second base sheet to correspond to the plurality of second contact points. is formed, and first and second adhesives are filled in each of the plurality of first grooves and the plurality of second grooves,
The first core sheet is attached to the first and second substrate sheets through the first and second adhesives.
According to claim 10,
A plastic substrate having an air layer between the adjacent first contact points or the adjacent second contact points.
According to claim 10,
The plastic substrate of claim 1 , wherein the first core sheet and the first and second base sheets have the same modulus value.
According to claim 10,
The first core sheet has a higher modulus value than the first and second base sheets,
The plastic substrate of claim 1 , wherein a vertical distance from one surface of the first base sheet in contact with the first core sheet to the second contact point is greater than a thickness of each of the first and second base sheets.
According to claim 10,
The first core sheet has a smaller modulus value than the first and second base sheets,
The plastic substrate of claim 1 , wherein a vertical distance from one surface of the first base sheet in contact with the first core sheet to the second contact point is smaller than a thickness of each of the first and second base sheets.
a plastic substrate according to any one of claims 1 to 7 and 9 to 14;
a light emitting diode positioned on the plastic substrate;
A thin film transistor positioned between the plastic substrate and the light emitting diode and connected to the light emitting diode
A display device including a.
first and second substrates facing each other;
a pixel electrode positioned on the first substrate;
a common electrode positioned on one of the first and second substrates;
A liquid crystal layer positioned between the first and second substrates;
At least one of the first and second substrates is a display device comprising a plastic substrate according to any one of claims 1 to 7 and 9 to 14.
The method according to any one of claims 1 to 7 and 9 to 14,
The plastic substrate of claim 1 , wherein each of the first and second base sheets is made of polyimide.

Images