KR20140113831A - Method of fabricating display device using flexible substrate - Google Patents

Abstract

The present invention provides a method for manufacturing a display device using a flexible substrate which comprises the step of: forming a flexible substrate by mixing a flexible substrate material and an epoxy additive represented by chemical formula on a carrier substrate; forming a display element on the flexible substrate; and irradiating a laser beam on the back surface of the carrier substrate to separate the flexible substrate. (In the chemical formula, each of X and Z is selected from -COO- or an alkyl group of C1-C10, Y is selected from an alicyclic ring compound or an aromatic ring compound, and n is an integer of 1-4.).

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a method of fabricating a display device using a flexible substrate,

The present invention relates to a display device using a flexible substrate, and more particularly, to a method of manufacturing a display device by coating a flexible substrate material containing an epoxy additive on a carrier substrate to improve adhesion between the carrier substrate and the flexible substrate without a separate adhesive layer, And a manufacturing method of a display device using a flexible substrate that can simplify the manufacturing process.

In recent years, as the society has become a full-fledged information age, a display field for processing and displaying a large amount of information has rapidly developed, and various flat panel display devices have been developed in response to this.

Specific examples of such a flat panel display include a liquid crystal display (LCD), a plasma display panel (PDP), a field emission display (FED), an organic light emitting diode (OELD). These flat panel display devices are superior in performance of thinning, light weight, and low power consumption, and are rapidly replacing existing cathode ray tubes (CRTs).

Such a flat panel display device is thin and light compared to a cathode ray tube (CRT), and is advantageous in that it is large in size.

However, such a flat panel display uses a glass substrate to withstand the high heat generated during the manufacturing process, and thus has a limitation in providing lightweight thinning and flexibility.

Therefore, a flexible display device which is manufactured so that the display performance can be maintained even if it is bent like paper by using a flexible material such as plastic instead of a conventional glass substrate having no flexibility is rapidly emerging as a next generation flat panel display device.

However, in manufacturing such a flexible display device, it is difficult to apply a substrate made of a plastic material, which is used to provide flexible characteristics, to a manufacturing apparatus for a conventional display device to be processed with a glass substrate because of its weak heat characteristic.

In particular, a low temperature poly silicon (LTPS) process using a polysilicon thin film transistor increases the process temperature to 400 to 500 DEG C, so it is difficult to apply a flexible substrate.

That is, unlike the manufacture of a display device using a general glass substrate, the manufacture of a display device using a flexible substrate causes a problem in an array process of forming a thin film transistor only on the flexible substrate itself.

In order to overcome this problem, the flexible substrate is attached to one side of a carrier substrate such as a glass substrate so that the substrate can be transported. Then, a general display device manufacturing process is performed to complete a flexible display device have.

The conventional method of manufacturing a flexible display device is divided into an adhesive process, a display element forming process, and a peeling process.

1A to 1C are schematic cross-sectional views illustrating a manufacturing process of a display device using a conventional flexible substrate. The constituent elements formed on the flexible substrate are omitted for convenience of explanation.

1A, hydrogenated amorphous silicon (a-Si: H) is deposited on a carrier substrate 5 made of a glass material capable of transmitting a laser beam to form a laser ablation layer 7 .

1B, a flexible substrate 10 is formed by applying a polymer material such as polyimide onto the laser ablation layer 7, and a display element is formed thereon.

For example, in the case of an organic light emitting diode display device, a thin film transistor and a light emitting diode can be formed on a flexible substrate 10.

 1C, a laser beam LB is applied to the front surface of the carrier substrate 5 by using a laser device 99 to transfer the flexible substrate 10 to the carrier substrate 5 ). When the laser beam LB is irradiated onto the ablation layer 7, hydrogen gas is discharged from the hydrogenated amorphous silicon (a-Si: H), whereby the gap between the flexible substrate 10 and the ablation layer 7 Adhesion is weakened. Thereafter, the flexible substrate 10 is separated through a vacuum adsorption process.

For example, polyimide, which is a material of the flexible substrate 10, has a poor adhesive force with the carrier substrate 5 made of glass. Therefore, in order to adhere the flexible substrate 10 to the carrier substrate 5, 7).

In addition, the ablation layer 7 is necessarily required to detach the flexible substrate 10 from the carrier substrate 5 after the display element manufacturing process.

Since the ablation layer 7 is formed by depositing hydrogenated amorphous silicon (a-Si: H) by a plasma enhanced chemical vapor deposition (PECVD) process, the process is complicated and the process time is increased.

Physical damage to the display element formed on the flexible substrate 10 also occurs due to the vacuum adsorption process for separating the flexible substrate 10.

An object of the present invention is to solve the problem of display element damage caused by an increase in the processing time by the step of attaching the flexible substrate to the carrier substrate and a step of detaching the flexible substrate from the carrier substrate.

In order to solve the above problems, the present invention provides a method of manufacturing a flexible substrate, comprising: forming a flexible substrate by mixing a flexible substrate material and an epoxy additive represented by the following formula on a carrier substrate; Forming a display element on the flexible substrate; And irradiating a laser beam onto a back surface of the carrier substrate to separate the flexible substrate from the flexible substrate.

(Wherein X and Z are each selected from the group consisting of? -, -COO- or C1-C10 alkyl groups, Y is selected from alicyclic ring compounds and aromatic ring compounds, and n is an integer of 1 to 4)

In the method of manufacturing a display device according to the present invention, the Y may be at least one selected from the group consisting of bisphenol-A, bisphenol-F, bisphenol-AD, bisphenol-S, hydrogenated bisphenol-A, naphthalene, phenol- novolak, glycidylamine, And dienes.

In the method for manufacturing a display device according to the present invention, the epoxy compound is one of the substances represented by the following formulas.

In the method of manufacturing a display device according to the present invention, the epoxy additive is added in an amount of 5.0 to 10.0 wt%.

In the method of manufacturing a display device according to the present invention, the ray point beam has a wavelength of 355 nm or 532 nm.

In the method of manufacturing a display device according to the present invention, the flexible substrate formed on the carrier substrate has a first thickness, and the flexible substrate separated from the carrier substrate has a second thickness smaller than the first thickness .

The flexible substrate of the present invention includes a flexible substrate material and an epoxy additive, so that it has excellent adhesion with the carrier substrate and can be detached from the carrier substrate by laser irradiation. Therefore, a separate adhesive layer forming step is omitted, which is advantageous in view of the time and cost of the display device manufacturing process.

Further, since the bonding between the flexible substrate and the epoxy additive is broken by laser beam irradiation, a flexible substrate having a thinner thickness can be obtained, thereby reducing the thickness of the display device.

Moreover, since such a desorption process does not require the substrate separation by vacuum adsorption, it is possible to prevent the display element from being damaged by the vacuum adsorption process.

1A to 1C are schematic cross-sectional views illustrating a manufacturing process of a display device using a conventional flexible substrate.
2A to 2E are schematic cross-sectional views illustrating a manufacturing process of a display device using a polyimide substrate according to the present invention.
Figs. 3A to 3C are photographs showing the adhesive strength depending on the content of the epoxy additive.
4 is a schematic cross-sectional view of a display device of a display device according to the present invention.

The present invention relates to a process for attaching and detaching a flexible substrate to a carrier substrate in manufacturing a display device using the flexible substrate.

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

2A to 2C are schematic cross-sectional views illustrating a manufacturing process of a display device using a flexible substrate according to the present invention.

As shown in FIG. 2A, a flexible substrate 120 having a first thickness t1 is formed by coating a flexible material on a carrier substrate 110. The flexible substrate 120 has a first thickness t1.

At this time, the flexible material includes a flexible substrate material 122 and an epoxy additive 124. The epoxy additive has a content of 0.01 to 50 wt%.

For example, the flexible substrate material may be a polyimide (PI), a polyamide (PA), a polyether sulfone (PES), a polycarbonate (PC), a polyarylate (PAR) , Polyethylene terephthalate (PET), polyethylene naphthalate (PEN), cycloolefin copolymer, epoxy resin, and unsaturated polyester.

The epoxy additive is represented by the following general formula (1). In the general formula (1), each of X and Z is selected from? -, -COO-, or C1-C10 alkyl groups, and X and Z are the same or different from each other. Y may be selected from an alicyclic ring compound and an aromatic ring compound. For example, Y can be selected from bisphenol-A, bisphenol-F, bisphenol-AD, bisphenol-S, hydrogenated bisphenol-A, naphthalene, phenol-novolak, glycidylamine, dicyclopentadiene. N is an integer of 1 to 4;

Formula 1

In the epoxy additive having the structure of Formula 1, X, Y, and Z have hydrophilic characteristics and the laser absorption wavelength is controlled.

For example, when the flexible substrate material 122 is made of polyimide, the polyimide has hydrophobic properties and therefore has poor adhesion to the carrier substrate 110 made of glass. However, since the epoxy additive 124 has a hydrophilic property, adhesion with the carrier substrate 110 is improved.

The epoxy additive 124 is collected on the lower portion of the flexible substrate 120 formed on the carrier substrate 110 and contacts the carrier substrate 110. A flexible substrate material 122 is formed on the flexible substrate 120, Respectively.

In other words, although the flexible substrate 120 is formed by a single coating process, the epoxy additive 124 is gathered at the lower portion of the flexible substrate 120 due to the hydrophilic property of the epoxy additive 124.

Also, the epoxy additive 124 has an epoxy group at the end, thereby having a cross-linking structure with the polyimide. Thus, the bonding force between the epoxy additive 124 and the flexible substrate material 122 is improved.

Figs. 3A to 3C are photographs showing the adhesive strength depending on the content of the epoxy additive.

The adhesion test was carried out by cross-cutting after forming a flexible substrate on a carrier substrate by adding an epoxy additive represented by the following formula (2) to the polyimide.

(2)

FIGS. 3A and 3B show a case where polyimide alone is formed on a carrier substrate without an epoxy additive and a cross-cutting test is conducted. FIGS. 3B and 3C show the case where epoxy additive of Formula 2 is added to polyimide at 5 wt% and 10 wt% This is the case where a flexible substrate is formed and a cross-cutting test is carried out.

As shown in FIG. 3A, since the polyimide has poor adhesion to the carrier substrate, it can be seen that a lot of flexible substrates are torn off when the cross-cutting test is performed.

However, as shown in FIGS. 3B and 3C, since the flexible substrate of the present invention includes an epoxy additive having good adhesion with the carrier substrate and having a polyimide cross-linking property, the damage of the flexible substrate in the cross- It can be seen that almost no occurrence occurs.

The flexible substrate 120 has excellent adhesion with the carrier substrate 110, which is a glass substrate. That is, since the flexible substrate 120 is attached to the carrier substrate 110 and the display element is formed on the flexible substrate 120, the flexible substrate 120 must have adhesion with the carrier substrate 110 to a certain extent or more.

However, when a flexible substrate is formed only of polyimide, adhesion with the carrier substrate is not good, so that a problem arises in the display element formation step. Therefore, in the case of forming a flexible substrate with only polyimide, an ablation layer (7 in Fig. 1A) was required for adhesion between the flexible substrate and the carrier substrate.

In other words, in the conventional method of manufacturing a display device using a flexible substrate, an ablation layer is formed on a carrier substrate, and then a flexible substrate is formed. At this time, since the hydrogenated amorphous silicon (a-Si: H) is deposited by the PECVD process to form the ablation layer, the process becomes complicated and the process time increases.

However, in the present invention, since the flexible substrate material such as polyimide is added and coated with the epoxy additive so as to have excellent adhesion with the carrier substrate 110, the flexible substrate 120 is directly formed on the carrier substrate 110, Time and process costs can be reduced.

Further, as described later, since the epoxy additive of the flexible substrate 120 is used for attaching / detaching the carrier substrate 110 and the polyimide substrate 120, no additional configuration is required.

Next, as shown in FIG. 2B, the display device 130 is formed on the flexible substrate 120.

For example, when the flexible substrate 120 is used as one substrate of the organic light emitting diode display, a switching thin film transistor and a driving thin film transistor are formed on the flexible substrate 120, A light emitting diode can be formed.

4, a semiconductor layer 132, a gate insulating film 134, a gate electrode 140, an interlayer insulating film 150, and a source (not shown) are formed on a flexible substrate 120 formed on a carrier substrate 110. [ The driving thin film transistor Dt including the electrode 162 and the drain electrode 164 is formed.

The semiconductor layer 132 includes an active region (not shown) at the center and source and drain regions (not shown) at both ends of the semiconductor layer 132. The gate insulating film 134 and the interlayer insulating film 150 are formed with the semiconductor layer 132 The first and second contact holes 152 and 154 are formed to expose the source region and the drain region.

The source electrode 162 and the drain electrode 164 are connected to the source region and the drain region of the semiconductor layer 132 through the first and second contact holes 152 and 154, 140 overlap the active region of the semiconductor layer 132 on the gate insulating layer 134.

A protective layer 170 having a third contact hole 172 exposing the drain electrode 164 is formed to cover the driving thin film transistor Dt.

A first electrode 182 connected to the drain electrode 164 is formed on the passivation layer 170 through the third contact hole 172 and a first electrode 182 connected to the drain electrode 164, (184).

An organic emission layer 186 is formed in the bank 184 to be in contact with the first electrode 182 and a second electrode 188 is formed to cover the organic emission layer 186 and the bank 184. [ .

The organic light emitting layer 186 between the first electrode 182, the second electrode 188 and the first and second electrodes 182 and 188 constitutes a light emitting diode De.

As described above, the step of forming the display element 130 can not proceed directly on the flexible substrate 120 without the carrier substrate 110. [ However, since the flexible substrate 120 is supported and fixed by the carrier substrate 110 in a state where the flexible substrate 120 is attached to the carrier substrate 110 as in the present invention, Forming process is possible.

2C, a laser beam LB is irradiated to the rear surface of the carrier substrate 110 to separate the flexible substrate 120 on which the display device 130 is formed from the carrier substrate 110 .

As described above, the flexible substrate 120 is brought into contact with the carrier substrate 110 due to the hydrophilic property of the epoxy additive 124, thereby forming a lower layer of the flexible substrate 120.

In this state, laser irradiation through the backside of the carrier substrate 110 destroys the bond between the epoxy additive 124 and the flexible substrate material 122. Accordingly, the flexible substrate 120 is detached from the carrier substrate 110.

Since the laser beam for desorption of the flexible substrate 120 may have a wavelength of 355 nm or 532 nm and the laser beam is absorbed by the epoxy additive 124, ) Does not occur.

The flexible substrate 120 having the first thickness t1 is coated on the carrier substrate 110 by the flexible substrate material 122 and the epoxy additive 124. The epoxy additive 124 and the epoxy additive 124 are coated with the laser beam, Since the bonding of the flexible substrate material 122 is broken, the thickness of the finally obtained flexible substrate becomes the second thickness t2 which is smaller than the first thickness t1. Therefore, it is advantageous to provide a thin display device.

Further, since the bonding of the flexible substrate material 122 such as polyimide and the epoxy additive 124 is destroyed by laser beam irradiation, a separate physical desorption process such as vacuum adsorption is not required. Therefore, damage can be prevented by the physical desorption process.

Meanwhile, the energy of the laser beam necessary for adhesion and desorption between the flexible substrate 120 and the carrier substrate 110 is determined by the content of the epoxy additive.

(Epoxy A) represented by the following formula (3) and an epoxy additive (Epoxy B) represented by the above formula (2) were added to the polyimide to form a flexible substrate and the laser beam used for adhesion and desorption of the flexible substrate and the carrier substrate ) Were measured and summarized in the table below.

(3)

As can be seen from the above table, when the flexible substrate does not contain epoxy, the contact force with the carrier substrate is very weak. When the content of epoxy is 10% or more, the adhesive force between the flexible substrate and the carrier substrate is converged to a specific value, but energy for desorption is increased.

The epoxy content in the flexible material may be 0.01 to 50 wt%, preferably 1.0 to 30 wt%, more preferably 5.0 to 10 wt%, in consideration of the adhesive force between the flexible substrate and the carrier substrate and the desorption energy.

In the present invention, a flexible substrate having excellent adhesion with the carrier substrate can be formed by a single coating step after the epoxy additive represented by the above formula (1) is added to a flexible substrate material such as polyimide. Therefore, the present invention has advantages in terms of manufacturing process and manufacturing cost as compared with the conventional flexible substrate in which a separate adhesive layer forming step is required.

In addition, since the bonding of the epoxy additive and the flexible substrate material is broken by the laser beam irradiated to the backside of the carrier substrate, the flexible substrate is separated from the carrier substrate naturally, so that no separate physical desorption process is required. Therefore, the manufacturing process is complicated by the physical desorption process and the display element is prevented from being damaged.

In addition, since only the upper flexible substrate material layer is separated while the epoxy additive is bonded to the carrier substrate, a thin display device can be provided.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the invention as defined in the appended claims. It can be understood that

110: Carrier substrate 120: Flexible substrate
130: display element

Claims (6)

Forming a flexible substrate by mixing a flexible substrate material and an epoxy additive represented by the following formula on a carrier substrate;
Forming a display element on the flexible substrate;
Irradiating a laser beam onto a back surface of the carrier substrate to separate the flexible substrate
The method comprising the steps of:

(Wherein X and Z are each selected from the group consisting of? -, -COO- or C1-C10 alkyl groups, Y is selected from alicyclic ring compounds and aromatic ring compounds, and n is an integer of 1 to 4)
The method according to claim 1,
Wherein Y is selected from the group consisting of bisphenol-A, bisphenol-F, bisphenol-AD, bisphenol-S, hydrogenated bisphenol-A, naphthalene, phenol-novolak, glycidylamine and dicyclopentadiene. A method of manufacturing a display device.
The method according to claim 1,
Wherein the epoxy compound is one of materials represented by the following chemical formulas.

The method according to claim 1,
Wherein the epoxy additive is added in an amount of 5.0 to 10.0 wt%.
The method according to claim 1,
Wherein the ray point beam has a wavelength of 355 nm or 532 nm.
The method according to claim 1,
Wherein the flexible substrate formed on the carrier substrate has a first thickness and the flexible substrate separated from the carrier substrate has a second thickness smaller than the first thickness. .

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