KR102469311B1 - Fabrication Method for Flexible Display Device - Google Patents

Abstract

The present invention relates to a method for manufacturing a flexible display device comprising forming a separation layer on a carrier substrate, manufacturing a color filter substrate by performing a process thereon, bonding it to a thin film transistor array substrate, and then removing the carrier substrate.

Description

Manufacturing method of flexible display device {Fabrication Method for Flexible Display Device}

The present invention relates to a method for manufacturing a flexible display device, and more specifically, to a method for manufacturing a flexible display device in which a process is performed on a carrier substrate.

A flexible display means a display that can be bent, bent, or rolled without loss of characteristics, and technology development is being made in the form of flexible LCD, flexible OLED, and electronic paper.

In order to realize flexible displays, various plastic substrates are being developed as flexible substrates that replace existing glass substrates, and substrates of various parts constituting flexible displays are being replaced with these plastic substrates from glass substrates. As a specific example, a color filter substrate including a film substrate made of polyimide disclosed in Korean Patent Registration No. 10-1174148 and a color filter part formed on the film substrate, or a flexible disclosed in Korean Patent Publication No. 10-2013-0047971 floor; a buffer layer applied to the entire upper surface of the flexible layer; a display element formed on an upper surface of the buffer layer; and a flexible organic light emitting diode display including a back panel attached to a rear surface of the flexible layer and having elasticity and flexibility to support the display element.

However, when using a flexible substrate, it is difficult to accurately arrange and form minute elements on a flexible substrate. To solve this problem, Korean Patent Registration No. 10-12670688 adheres a film substrate to a carrier substrate made of glass. A method of forming a device thereon and removing the carrier substrate is proposed.

However, since such a film substrate has a lower transition temperature and a higher expansion rate according to temperature change than glass, layers stacked thereon may be destroyed or deformed.

In addition, when the color filter substrate and the thin film transistor array substrate are separately formed on a flexible substrate and combined to manufacture a flexible display device, a large alignment error occurs because the film substrate, which is a flexible substrate, must be bonded in a transfer method. .

Republic of Korea Patent No. 10-1174148 Republic of Korea Patent Publication No. 10-2013-0047971 Republic of Korea Patent No. 10-12670688

The present invention is to solve the problem of manufacturing a flexible display device in the prior art, and when manufacturing a flexible display device in which a color filter substrate and a thin film transistor array substrate are formed on separate flexible substrates, the two substrates are aligned. An object of the present invention is to provide a manufacturing method of a flexible display device capable of reducing errors.

Another object of the present invention is to provide a method for manufacturing a flexible display device including a color filter substrate capable of obtaining a high-definition pattern that is difficult to implement on a conventional plastic substrate, solving thermal instability, and applying base films of various materials. is to do

In order to solve this problem, the present invention comprises the steps of forming a separation layer by applying a composition for forming a separation layer on a first carrier substrate; forming a protective layer by applying a composition for forming a protective layer on the separation layer; forming a black matrix (BM) layer on the protective layer and forming a colored layer therebetween; aligning and adhering the first carrier substrate on which the separation layer, the passivation layer, the BM layer, and the coloring layer are formed to a thin film transistor (TFT) array substrate; and removing the first carrier substrate.

The manufacturing method of the flexible display device of the present invention may further include attaching a flexible base film on the surface of the separation layer from which the first carrier substrate is removed.

The TFT array substrate may include an organic light emitting diode (OLED).

The TFT array substrate may include a second carrier substrate, and in this case, the step of removing the second carrier substrate may be further included after the aligning and bonding step. The first and second carrier substrates may be removed simultaneously.

The protective layer is preferably formed to cover up to the side surface of the separation layer, and the protective layer may include at least one of an organic insulating layer and an inorganic insulating layer.

The manufacturing method of the flexible display device of the present invention may further include forming a planarization layer by applying a composition for forming a planarization layer on the BM layer and the coloring layer.

In the aligning and bonding step, the separation layer, the protection layer, the BM layer, and the coloring layer are formed by using a key formed on the first carrier substrate and the TFT array substrate on which the separation layer, the protection layer, the BM layer, and the coloring layer are respectively formed. It is preferable to align the first carrier substrate on which layers are formed and the TFT array substrate with an alignment error of 5 μm or less.

In the aligning and bonding step, the TFT array substrate may be bonded to the first carrier substrate on which the separation layer, the protective layer, the BM layer, and the coloring layer are formed using an optical adhesive film or an optical adhesive resin.

According to the manufacturing method of the flexible display device according to the present invention, the manufacturing process of the color filter is performed on a glass substrate rather than a base film made of plastic, thereby solving the problem caused by thermal deformation of the conventional plastic substrate as well as the plastic substrate. Fixed taxation of patterns that could not be implemented in

In addition, alignment errors between the color filter substrate and the thin film transistor array substrate can be significantly reduced by aligning and combining the color filter substrate formed on the glass substrate and the thin film transistor array substrate also formed on the glass substrate.

In addition, after combining the color filter substrate and the thin film transistor array substrate, the glass substrate, which is the carrier substrate, is removed at room temperature and the base film is separately bonded, thereby solving the problem caused by thermal deformation of the conventional plastic substrate, as well as the material of the base film It is possible to secure the advantage of being able to diversify without restrictions on

1 is a cross-sectional view of a flexible display device according to an embodiment of the present invention.
2 to 11 are cross-sectional views of each step of a manufacturing method of a flexible display device according to an embodiment of the present invention.

The present invention provides a method for manufacturing a flexible display device capable of producing a high-definition pattern and minimizing alignment errors including a flexible color filter substrate having no limitation on the material of the plastic substrate.

Hereinafter, preferred embodiments of a flexible display device and a manufacturing method thereof according to the present invention will be described in detail with reference to the drawings. However, the drawings attached to this specification are only examples for explaining the present invention, and the present invention is not limited by the drawings. In addition, for convenience of description, some components may be exaggeratedly expressed, reduced, or omitted in the drawings.

1 is a cross-sectional view of a flexible display device according to an embodiment of the present invention.

Referring to FIG. 1, a flexible display device according to an embodiment of the present invention includes a TFT+OLED substrate (thin film transistor, TFT) and an organic light emitting diode (OLED) array formed thereon. 200), a color filter (CF) substrate (hereinafter referred to as CF substrate) 100, and an adhesive layer 300 adhering them.

In the flexible display device according to an embodiment of the present invention, the CF substrate 100 and the TFT+OLED substrate 200 are flexible substrates on which necessary components are disposed on the flexible base films 110 and 210, respectively. A flexible display device formed by bonding two substrates 100 and 200 is provided. In addition, each of the components disposed on the flexible substrate films 110 and 210 also provides flexibility characteristics for the flexible display device as needed.

Specifically, the CF substrate 100 includes a base film 110, a separation layer 120, a protective layer 130, a black matrix (BM) layer 140, a coloring layer 150, and a planarization layer 160. ) has a sequentially stacked structure.

In the present invention, in order to provide a flexible CF substrate, at least one of the layers constituting the CF substrate 100, preferably the separation layer 120 or the protective layer 130, more preferably the separation layer 120 is an organic layer can be

A polymer material may be used as a material of the organic layer. The polymer material is, for example, polyacrylate, polymethacrylate (eg PMMA), polyimide, polyamide, polyvinyl alcohol, polyamic acid (polyamic acid), polyolefin (e.g. PE, PP), polystyrene, polynorbornene, phenylmaleimide copolymer, polyazobenzene, polyphenylenephthal Amide (polyphenylenephthalamide), polyester (e.g., PET, PBT), polyarylate, cinnamate-based polymer, coumarin-based polymer, phthalimidine-based polymer, It includes at least one material selected from the group consisting of chalcone-based polymers and aromatic acetylene-based polymers.

The polymer material is one selected from the group consisting of a base film 110, a separation layer 120, a protective layer 130, a BM layer 140, a coloring layer 150, and a flattening layer 160, and combinations thereof Applicable to the above layers. For example, the same or similar polymer may be applied to all layers, or polyacrylate may be applied only to the separation layer 120, and materials known in the art may be used for the other layers.

Hereinafter, each layer constituting the flexible CF substrate 100 according to the present invention will be described in detail.

As the base film 110, those commonly used as transparent films for optics may be used without limitation, but among them, it is preferable to use a film having excellent flexibility, transparency, thermal stability, moisture shielding property, retardation uniformity, isotropy, and the like.

The material of the base film 110 may be the above-described polymer material or commonly used polyethylene terephthalate, polyethylene, polystyrene, polycarbonate, polyimide, or the like.

The separation layer 120 is a layer formed for separation from the carrier substrate after bonding of the flexible CF substrate 100 and the TFT+OLED substrate 200 is completed in the manufacturing process of the flexible display device of the present invention.

Therefore, the separation layer 120 must be separated from the carrier substrate through physical force, and after separation, it is laminated with the base film 110 . Therefore, the peel force of the separation layer 120 to the glass substrate may be 5 N / 25 mm or less, preferably, the peel force of the separation layer 120 may be 1 N / 25 mm or less, more preferably 0.1 N / 25 mm or less do. That is, it is preferable that the separation layer 120 is formed of a material that prevents the physical force applied during separation of the separation layer 120 from the carrier substrate from exceeding 1 N/25 mm, particularly 0.1 N/25 mm.

When the peel force of the separation layer 120 exceeds 1 N/25 mm, it is not neatly separated during separation from the carrier substrate, and there is a possibility that the separation layer 120 remains on the carrier substrate, and also the separation layer 120 This is because cracks may occur in one or more of the protective layer 130, the BM layer 140, the coloring layer 150, and the planarization layer 160.

In particular, the peeling force of the separation layer (120) is more preferably 0.1 N / 25 mm or less, and in the case of 0.1 N / 25 mm or less, it is more preferable in that curl generated in the film after peeling from the carrier substrate can be controlled. do. Curl does not cause a problem in terms of the flexible CF substrate, but it is advantageous to reduce the occurrence because it can reduce process efficiency in processes such as bonding process and cutting process.

Here, the thickness of the separation layer 120 is preferably 10 to 1000 nm, more preferably 50 to 500 nm. If the thickness of the separation layer 120 is less than 10 nm, the uniformity at the time of application of the separation layer is poor, resulting in uneven pattern formation, or local peeling force is increased to cause tearing, or after separation from the carrier substrate, curl is not controlled. There is a problem. And when the thickness exceeds 1000nm, there is a problem that the peeling force is no longer lowered, and there is a problem that the flexibility of the film is lowered.

In addition, the separation layer 120 preferably has a surface energy difference of 30 to 70 mN/m after separation from the carrier substrate, and a surface energy difference between the separation layer 120 and the carrier substrate is preferably 10 mN/m or more. In the manufacturing process of the flexible display device, the separation layer 120 must be stably adhered to the carrier substrate until it is peeled off from the carrier substrate, and when peeled from the carrier substrate, it is easily peeled so that the flexible color filter does not tear or curl. It should be. When the surface energy of the separation layer 120 is set to 30 to 70 mN/m after separation, the peeling force can be adjusted, and the adhesion between the separation layer 120 and the adjacent protective layer 130 is secured to improve process efficiency. . In addition, when the difference in surface energy between the separation layer 120 and the carrier substrate is 10 mN/m or more, it is smoothly separated from the carrier substrate to prevent tearing or cracking.

The protective layer 130 is a layer for protecting the separation layer 120 and has an encapsulated form to surround both sides of the separation layer 120 . The protective layer may be formed of the organic layer described above, but may also be formed of an inorganic insulating film.

The coloring layer 150 is a layer for realizing colors for color display, and is typically patterned with red, green, blue, and white, and light in areas other than pixel areas. It is disposed between the BM layer 140, which is a light blocking layer that serves to block the. However, the coloring layer does not have to include all of the red, green, blue, and white patterns, and may include only some of the patterns of any of these colors according to the color expression method of the flexible display device.

On the other hand, when the external light reaches the colored layer of each color, only the light having the wavelength of the corresponding color is transmitted and the light having the wavelength of the other two colors is absorbed, so that the incident light amount of the external light can be effectively reduced, so that the colored layer is a polarizing plate for preventing reflection of external light. It can also perform a function instead of .

The flattening layer 160 is a layer for correcting the level difference of the colored layer 150 and improving the flatness, and the material thereof is not particularly limited in the present invention, and may be polyacrylate, polyimide, polyester, etc., which are commonly used. can

The thickness of each of the organic layers is not particularly limited in the present invention, but thinner is more advantageous for thinning the flexible CF substrate and the applied flexible display. Therefore, the thickness of each organic layer is preferably several micrometers (μm) or less.

Preferably, the flexible CF substrate 100 according to an embodiment of the present invention

a base film 110 made of polyimide and having a thickness of 10 to 100 μm;

A separation layer 120 made of polyacrylic material and having a thickness of 0.01 to 1.0 μm;

a protective layer 130 made of a polycycloolefin-based material and having a thickness of 0.5 to 5 μm;

a colored layer 150 having a thickness of 0.5 to 5 μm; and

It is a polyacrylic material and may include a planarization layer 160 having a thickness of 0.5 to 5 μm.

On the other hand, the TFT+OLED substrate 200 has a structure in which a base film 210, a TFT layer 220, an OLED layer 230, and an encapsulation layer 240 are sequentially stacked, and the structure of the present invention not particularly limited in Also, the TFT+OLED substrate 200 can be manufactured in any manner known in the field of flexible display technology.

In the flexible display device of the present invention, the BM layer 140 and the color layer 150 pattern of the flexible CF substrate 100 and the TFT layer 220 and OLED layer 230 of the TFT+OLED substrate 200 are conventional films Unlike the case of using a type color filter, it is precisely aligned with an alignment error of 5 μm or less. The alignment of the substrate will be described in more detail in relation to the manufacturing method of the flexible display device according to the present invention.

An adhesive layer 300 bonding the two substrates is formed between the flexible CF substrate 100 and the TFT+OLED substrate 200 . The adhesive layer 300 is made of optically clear adhesive (OCA) or optically clear resin (OCR).

2 to 11 are cross-sectional views of each step according to a manufacturing method of a flexible display device according to an embodiment of the present invention.

In the method for manufacturing a flexible display device according to an embodiment of the present invention, a flexible CF substrate, which can be formed on a carrier substrate to produce a high-definition pattern and has no limitation on the material of a plastic substrate, is aligned and adhered to a TFT+OLED substrate. After separating the carrier substrate, alignment errors can be minimized.

First, as shown in FIG. 2 , after preparing the first carrier substrate 170 , the separation layer 120 is formed by applying a composition for forming a separation layer.

It is preferable to use a glass substrate as the first carrier substrate 170, but other materials may be used without being limited thereto. However, a material having heat resistance that does not deform even at a high temperature, that is, can maintain flatness, is preferable so that it can withstand the subsequent process temperature.

As a method of applying the composition for forming a separation layer, a known coating method may be used. Examples include spin coating, die coating, spray coating, roll coating, screen coating, slit coating, dip coating, and gravure coating. Alternatively, an inkjet method may be used.

The composition for forming the separation layer is cured after coating to form the separation layer 120 . In this case, as the curing process, thermal curing or UV curing may be used alone or a combination of thermal curing and UV curing may be used. When using thermal curing, it can be heated by an oven, hot plate, etc., and the heating temperature and time may vary depending on the composition, but for example, heat treatment may be performed at 80 to 250 ° C. for 10 to 120 minutes.

Next, as shown in FIG. 3, a protective layer 130 is formed by applying a composition for forming a protective layer on the formed separation layer 120 to cover up to the side of the separation layer.

As described above, the separation layer 120 may be peeled off by physical force, and since the peeling force is very weak, it is preferable that the protective layer is formed in a form surrounding both sides.

The coating method and curing process of the composition for forming a protective layer are as described above.

Next, as shown in FIGS. 4 and 5, a BM layer 140 is formed on the formed protective layer 130, and red (R), green (G), blue (B), and white ( In forming the colored layer 150 of W), first, the BM layer 140 is formed to partition the portion where pixels are formed on the protective layer 130, and then each composition for forming a colored layer for color expression is applied. It is coated and formed by exposure, development, and heat curing in a predetermined pattern. The color constituting the colored layer may be arbitrarily selected, and the order of forming each color may also be arbitrarily selected.

The coating method and curing process of the BM layer 140 and the colored layer 150 are as described above.

Meanwhile, in the process of forming the BM layer 140, alignment keys (not shown) for alignment with the TFT+OLED substrate 200 are formed together.

In addition, the formation order of the BM layer 140 and the coloring layer 150 may vary as needed. That is, it is also possible to pattern the coloring layer 150 first and then form the BM layer 140 layer.

Next, as shown in FIG. 6 , a planarization layer 160 is formed by applying a composition for forming a planarization layer over the formed BM layer 140 and the coloring layer 150 .

Meanwhile, the TFT+OLED substrate 200 as shown in FIG. 7 is formed on the second carrier substrate 270 in a process separate from that described with reference to FIGS. 2 to 6 . The TFT+OLED substrate 200 may be manufactured by any method known in the field of flexible display technology, and the manufacturing process is not particularly limited in the present invention.

The second carrier substrate 270 also preferably uses a glass substrate like the first carrier substrate 170, but is not limited thereto and other materials may be used. Also, a material having heat resistance that is not deformed even at a high temperature, that is, can maintain flatness so as to withstand the process temperature for subsequent TFT and OLED manufacturing is preferable.

In addition, an alignment key (not shown) for aligning with the CF substrate is formed on the TFT+OLED substrate 200 in a certain process of the manufacturing process. For example, an alignment key may be formed in a metal layer forming process for forming wiring.

Now, as shown in FIG. 8, through the process of FIGS. 2 to 6, the separation layer 120, the protective layer 130, the BM layer 140, the coloring layer 150, and the planarization layer 160 are formed. The TFT+OLED substrate 200 formed on the first carrier substrate 170 and the second carrier substrate 270 are aligned. At this time, the alignment is performed using an alignment key formed on the BM layer 140 of the first carrier substrate 170 and an alignment key formed on the metal layer of the TFT+OLED substrate 200, and the alignment accuracy is to be 5 μm or less. can

The alignment key may be formed at an outermost portion of clustered panels, which is an edge of a glass substrate or an outer portion where a panel in the substrate is cut.

In particular, since the process of manufacturing the color filter on the first carrier substrate 170 and the process of manufacturing the TFT and OLED array on the second carrier substrate 270 are usually performed as separate processes, the predetermined alignment key is moved to a predetermined position. separately formed to align the two substrates.

As in the prior art, when a CF substrate formed on a film substrate, which is a flexible substrate, is bonded to a TFT+OLED substrate by a transfer method, an alignment error is about 500 μm. However, according to an embodiment of the present invention, the separation layer 120, the protective layer 130, the BM layer 140, the coloring layer 150, and the planarization layer 160 are formed on the first carrier substrate 170 and Since the TFT+OLED substrate 200 formed on the second carrier substrate 270 is aligned without removing the first and second carrier substrates 170 and 270 that are glass substrates, alignment accuracy can be remarkably improved. Specifically, the alignment error can be reduced to about 5 μm, which is a level of 1/100.

Next, as shown in FIG. 9, the two aligned substrates are bonded. Conjugation can be done using OCA or OCR. Adhesion of the substrate may be performed in any method known in the field of flexible display technology, and the process is not particularly limited in the present invention.

Now, as shown in FIG. 10 , the first carrier substrate 170 and the second carrier substrate 270 are separated. At this time, the first carrier substrate 170 and the second carrier substrate 270 may be separated simultaneously or sequentially, or may be separated in an arbitrary order when sequentially separated.

In particular, the process of separating the first carrier substrate 170 from the separation layer 120 is performed at room temperature, and for example, physical separation of the first carrier substrate 170, which is a glass substrate, from the separation layer 120. method can be performed.

A peeling method includes a lift-off or a peel-off method, but is not limited thereto.

The characteristics of the separation layer 120, such as peeling force, thickness, and surface energy difference from the carrier substrate after peeling, are the same as previously presented in the detailed description of the structure of the flexible display device according to an embodiment of the present invention, through which While the separation layer 20 is neatly separated without remaining on the carrier substrate, cracks do not occur and curl can be controlled.

Next, as shown in FIG. 11 , the base film 110 is adhered to the separation layer 120 .

The base film 110 has flexibility and can be selected suitable for a desired purpose from among the above materials.

Although not shown in the drawing, the base film 110 may be adhered to the separation layer 120 using an adhesive layer, and the usable adhesive is a photocurable adhesive and does not require a separate drying process after photocuring. The process is simple and productivity is improved. As the photocurable adhesive used in the present invention, a photocurable adhesive used in the field may be used without particular limitation. For example, a composition containing an epoxy compound or an acrylic monomer may be used.

In addition, in the photocuring of the adhesive layer, electron beams, proton rays, neutral rays, etc. can be used in addition to rays such as far ultraviolet rays, ultraviolet rays, near ultraviolet rays, infrared rays, X-rays, and γ-rays, but the curing speed, Curing by ultraviolet irradiation is advantageous in view of the availability of the irradiation device, price, and the like.

As a light source for performing ultraviolet irradiation, a high-pressure mercury-vapor lamp, an electrodeless lamp, an ultra-high-pressure mercury-vapor lamp carbon arc lamp, a xenon lamp, a metal halide lamp, a chemical lamp, a black light, or the like can be used.

Meanwhile, in the above-described embodiment of the present invention, a method for manufacturing a flexible OLED display device by combining a CF substrate and a TFT+OLED substrate in which an OLED is formed on a TFT has been described, but the present invention is not limited thereto. For example, even in the case of manufacturing a flexible liquid crystal display device by inserting a liquid crystal layer between a TFT array substrate and a CF substrate instead of OLED, a method of manufacturing a flexible display device of the present invention by adding a range obvious to a person skilled in the art this can be used

As described above, it will be understood that the present invention can be implemented in various modified forms without departing from the essential characteristics of the present invention.

Therefore, the specified embodiments should be considered from a descriptive point of view rather than a limiting point of view, and the scope of the present invention is shown in the claims rather than the foregoing description, and all differences within the equivalent scope are considered to be included in the present invention. will have to be interpreted

100: color filter substrate 110: base film
120: separation layer 130: protective layer
140: black matrix layer 150: colored layer
160: planarization layer 170: first carrier substrate
200: TFT + OLED substrate 210: base film
220: TFT layer 230: OLED layer
240: encapsulation layer 270: second carrier substrate
300: adhesive layer

Claims (10)

A separation layer is formed by applying a composition for forming a separation layer on a first carrier substrate, wherein the separation layer has a peel force of 0.1 N/25 mm or less from the first carrier substrate, and surface energy after separation from the first carrier substrate making a difference of 30 to 70 mN/m and a thickness of 10 to 1,000 nm;
Forming a protective layer of an organic insulating film or an inorganic insulating film by applying a composition for forming a protective layer on the separation layer, wherein the protective layer is formed to a thickness of 500 to 5,000 nm while surrounding upper and side surfaces of the separation layer;
forming a black matrix (BM) layer on the protective layer and forming a colored layer therebetween;
aligning and adhering the first carrier substrate on which the separation layer, the protective layer, the BM layer, and the coloring layer are formed to a thin film transistor (TFT) array substrate; and
removing the first carrier substrate;
Method of manufacturing a flexible display device comprising a. According to claim 1,
Further comprising the step of attaching a flexible base film on the surface of the separation layer from which the first carrier substrate is removed,
A method for manufacturing a flexible display device. According to claim 1,
The TFT array substrate includes an organic light emitting diode (OLED),
A method for manufacturing a flexible display device. According to claim 1,
The TFT array substrate includes a second carrier substrate,
After the aligning and bonding steps,
Further comprising removing the second carrier substrate,
A method for manufacturing a flexible display device. According to claim 4,
The first and second carrier substrates are removed simultaneously,
A method for manufacturing a flexible display device. delete delete According to claim 1,
forming a planarization layer by applying a composition for forming a planarization layer on the BM layer and the colored layer;
Method of manufacturing a flexible display device further comprising a. According to claim 1,
In the aligning and bonding step, the separation layer, the protection layer, the BM layer, and the coloring layer are formed by using a key formed on the first carrier substrate and the TFT array substrate on which the separation layer, the protection layer, the BM layer, and the coloring layer are respectively formed. Aligning the first carrier substrate on which the layer is formed and the TFT array substrate with an alignment error of 5 μm or less,
A method for manufacturing a flexible display device. According to claim 1,
In the aligning and bonding step, the first carrier substrate on which the separation layer, the protective layer, the BM layer, and the colored layer are formed using an optically clear adhesive (OCA) or an optically clear resin (OCR) And bonding the TFT array substrate,
A method for manufacturing a flexible display device.

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