TWI703721B - Method of manufacturing flexible display device - Google Patents

Abstract

The present invention relates to a method of manufacturing a flexible display device in which a color filter substrate is prepared by forming a separation layer on a carrier substrate and performing subsequent procedures thereon, the color filter substrate is attached with a thin film transistor substrate, and the carrier substrate is removed therefrom.

Description

Method for manufacturing flexible display device

The present invention relates to a method of manufacturing a flexible display device. In particular, the present invention relates to a method of manufacturing a flexible display device by executing a program on a carrier substrate.

A flexible display refers to a display that can be bent, folded or rolled up without compromising its properties, and it can be a flexible LCD, a flexible OLED, electronic paper, etc.

In order to realize flexible displays, various plastic substrates have been developed as flexible substrates to replace conventional glass substrates, and the substrates of various components constituting the flexible display have been replaced by such plastic substrates. For example, Korean Patent No. 10-1174148 discloses a color filter substrate including a film substrate made of polyimide and a color filter portion formed on the film substrate, and Korean Patent Application Publication Case No. 10-2013-0047971 discloses a flexible organic light-emitting diode display device, which includes: a flexible layer; a buffer layer, which is applied on the entire upper surface of the flexible layer; A display element formed on an upper surface of the buffer layer; and a back panel having elasticity and flexibility attached to the back surface of the flexible layer and supporting the display element.

However, when a flexible substrate is used, it is difficult to accurately arrange fine components on a flexible substrate. To solve this problem, Korean Patent Publication No. 10-12670688 discloses a method of attaching a film substrate to a carrier substrate made of glass, forming elements thereon, and then removing the carrier substrate.

However, since the transition temperature of the film substrate is lower than the transition temperature of the glass substrate, and the film substrate has a high expansion rate due to temperature changes, there may be a problem that the layers stacked thereon may be destroyed or deformed.

In addition, when a color filter substrate and a thin film transistor array substrate are separately formed on the flexible substrate and assembled to form a flexible display device, a large misalignment should be caused by using a transfer method to attach It is connected to the flexible film substrate.

An object of the present invention is to provide a method for manufacturing a flexible display device, when manufacturing a flexible display with a color filter substrate and a thin film transistor array substrate formed on separate flexible substrates When installing, this method can reduce the alignment error of one of the two substrates.

Another object of the present invention is to provide a method for manufacturing a flexible display device including a color filter substrate. The method can obtain a high-resolution pattern that is difficult to implement on a conventional plastic substrate and solve the thermal problem. Stable and apply a base film of one of various materials.

According to one aspect of the present invention, there is provided a method of manufacturing a flexible display device, which includes the following steps: forming a separation layer on a first carrier substrate; forming a protective layer on the separation layer; A black matrix (BM) layer is formed on the layer and a colorant layer is formed in the middle; the first carrier substrate on which the separation layer, the protective layer, the BM layer, and the colorant layer are formed is aligned with a Attaching and attaching a thin film transistor (TFT) array substrate; and removing the first carrier substrate.

The method of manufacturing a flexible display device may further include a step of attaching a flexible base film to a 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 the method of manufacturing a flexible display device may further include a step of removing the second carrier substrate after the alignment and attachment steps. In addition, the first carrier substrate and the second carrier substrate can be removed at the same time.

The protective layer may be formed to cover one side surface of the separation layer. Furthermore, the protective layer may include at least one of an organic insulating film and an inorganic insulating film.

The method of manufacturing a flexible display device may further include a step of forming a planarization layer on the BM layer and the colorant layer.

In the alignment and attachment step, the alignment may be formed on the first carrier substrate and the TFT array substrate on which the separation layer, the protective layer, the BM layer, and the colorant layer are formed, respectively The alignment key can be performed, and the alignment can be performed with an alignment error of 5 μm or less.

In the alignment and attachment step, an optically clear adhesive (OCA) or an optically clear resin (OCR) may be used to attach the separation layer, the protective layer, the BM layer, and the The first carrier substrate of the colorant layer and the TFT array substrate.

According to the method of manufacturing a flexible display device of the present invention, the color filter manufacturing process can be performed on a glass substrate instead of a base film made of plastic, thereby solving the thermal deformation problem of the conventional plastic substrate. It can form a high-resolution pattern that cannot be implemented on a plastic substrate.

Furthermore, by aligning the color filter substrate formed on the glass substrate and the thin film transistor array substrate also formed on the glass substrate and combining them, the color filter substrate and the thin film electricity can be significantly reduced. Alignment errors between crystal array substrates.

In addition, since the glass substrate as the carrier substrate is removed at room temperature after the color filter substrate and the thin film transistor array substrate are adhered and the base film is attached separately, the thermal deformation problem of the conventional plastic substrate is solved . The diversification of base film materials can also advantageously be unlimited.

100: Color filter (CF) substrate

110: basement membrane

120: separation layer

130: protective layer

140: Black matrix (BM) layer

150: colorant layer

160: Planarization layer

170: first carrier substrate

200: thin film transistor (TFT) + organic light emitting diode (OLED) substrate

210: basement membrane

220: Thin film transistor (TFT) layer

230: Organic Light Emitting Diode (OLED) layer

240: encapsulation layer

270: second carrier substrate

300: Adhesive layer

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

2 to 11 schematically show the procedure of an embodiment of the method for manufacturing a flexible display device according to the present invention.

The present invention provides a method for manufacturing a flexible display device with minimized alignment errors, in which high-resolution patterns can be achieved and the material of the plastic substrate is not limited.

Hereinafter, a preferred embodiment of a flexible display device and a manufacturing method thereof will be described in detail with reference to the accompanying drawings. However, the drawings attached to the present invention are only examples for describing the present invention, and the present invention is not limited by the drawings. Furthermore, for clearer presentation, some elements can be enlarged, scaled down or omitted in the drawing.

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

1, a flexible display device according to an embodiment of the present invention includes a TFT+OLED substrate 200 having an array of thin film transistors (TFT) and organic light emitting diodes (OLED), and a color filter The sheet (CF) substrate 100 and one of the adhesive layers 300 therebetween.

In a flexible display device according to an embodiment of the present invention, the CF substrate 100 and the TFT+OLED substrate 200 are flexible substrates, and the required components are respectively arranged on the flexible base films 110 and 210, by This provides a flexible display device composed of two substrates 100 and 200 adhered to each other. In addition, the elements arranged on the flexible base films 110 and 210 provide the flexibility of the flexible display device as required.

Specifically, the CF substrate 100 includes a base film 110, a separation layer 120, a protection layer 130, a black matrix (BM) layer 140, a colorant layer 150, and a planarization layer 160, which depend on Stack in this order.

According to the present invention, 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) may be an organic layer to provide a flexible CF substrate.

The organic layer can be made of an organic polymer. The organic polymer may include at least one selected from the group consisting of: polyacrylate, polymethacrylate (for example, PMMA), polyimide, polyamide, polyvinyl alcohol, polyamide Acid, polyolefin (e.g., PE, PP), polystyrene, polynorbornene, phenyl maleimide copolymer, polyazobenzene, polyphenylene phthalimide, polyester ( For example, PET, PBT), polyarylate, cinnamate polymer, coumarin polymer, benzalactamide polymer, chalcone polymer, and aromatic acetylene polymer.

The above polymer is suitable for at least one layer selected from the group consisting of: base film 110, separation layer 120, protective layer 130, BM layer 140, colorant layer 150, planarization layer 160, and combinations thereof. For example, the same or similar polymer may be applied to each layer, or polyacrylate may only be applied to the separation layer 120, and the remaining layers may be made of materials known in the art.

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

The base film 110 may be any film commonly used as an optically transparent film, and it is preferable to use a film having excellent flexibility, transparency, thermal stability, moisture-proof properties, phase difference uniformity, isotropy, etc.

Specific examples of the material used for the base film 110 include the polymer described above or polymers commonly used in the art, such as polyethylene terephthalate, polyethylene, polystyrene, polycarbonate, and polyamide. Imines and so on.

The separation layer 120 is formed to peel off a layer from a carrier substrate after the flexible CF substrate 100 and the TFT+OLED substrate 200 are adhered in the manufacturing method of the present invention.

Therefore, the separation layer 120 can be separated from the carrier substrate by a physical force and laminated on the base film 110 after separation. When the separation layer 120 is separated from the carrier substrate, it may have 5N/25 mm or less, preferably 1N/25mm or less, more preferably 0.1N/25mm or less. That is, the separation layer 120 is preferably formed of a material that can maintain a physical force applied during the separation of the separation layer 120 from the carrier substrate within 1 N/25 mm, especially within 0.1 N/25 mm.

If the peel strength of the separation layer 120 exceeds 1N/25 mm, it is difficult to cleanly separate the separation layer 120 from the carrier substrate, and therefore the separation layer 120 may remain on the carrier substrate. Furthermore, cracks may be generated on one or more of the separation layer 120, the protection layer 130, the BM layer 140, the colorant layer 150, and the planarization layer 160.

In particular, the peel strength of the separation layer 120 is preferably 0.1 N/25 mm or less, because this allows control of curling in the film after separation from the carrier substrate. Crimping can degrade the efficiency of the adhesion and cutting process, even if it does not affect the function of the flexible CF substrate itself. Therefore, it is advantageous to minimize curling.

The separation layer 120 preferably has a thickness of 10 nm to 1000 nm, more preferably 50 nm to 500 nm. If the thickness of the separation layer 120 is less than 10 nm, the separation layer may be unevenly formed to induce the formation of uneven patterns thereon, the peel strength of the separation layer 120 may be locally increased to cause cracks, or curling control may be in the separation layer 120 It fails after being separated from the carrier substrate. If the thickness of the separation layer 120 is greater than 1000 nm, the peel strength of the separation layer 120 can no longer be reduced, and the flexibility may be deteriorated.

The separation layer 120 preferably has a surface energy ranging from 30 mN/m to 70 mN/m after being peeled from the carrier substrate. Furthermore, the separation layer 120 preferably has a surface energy difference of 10 mN/m or more between it and the carrier substrate. The separation layer 120 should maintain stable adhesion to the carrier substrate until it is separated from the carrier substrate, and then should be easily separated without cracking or curling of the flexible CF substrate. When the surface energy of the separation layer 120 falls within the range of 30 mN/m to 70 mN/m, its peel strength can be controlled to ensure good adhesion between the separation layer 120 and the adjacent protective layer 130 to improve the efficiency of the process. Furthermore, when the separation layer 120 meets the 10 mN/m or more between it and the carrier substrate When the surface energy is poor, the separation layer 120 can be easily separated from the carrier substrate to prevent the flexible CF substrate from being broken or the flexible CF substrate from being cracked.

The protective layer 130 protects the separation layer 120 and has an encapsulation form to cover the side surface of the separation layer 120. The protective layer can be made of the organic material described above, or it can be made of an inorganic material.

The colorant layer 150 is used to implement full-color display, and usually red, green, blue, and white colors are patterned and arranged in the middle of the BM layer 140. The BM layer 140 is used to block light in areas other than the pixel area. However, the colorant layer does not necessarily include all red, green, blue, and white patterns. In fact, according to the color model, only some patterns of these colors can be included.

At the same time, when the external light reaches the coloring agent layer of each color, only the light with the respective wavelength is transmitted, and the light with other wavelengths is absorbed. Therefore, the amount of incident light of external light can be effectively reduced, which allows the colorant layer to act as a polarizing plate to prevent reflection of external light.

The planarization layer 160 is a layer for compensating the steps of the colorant layer 150 and improving the flatness, and its material is not specifically limited in the present invention. For example, common materials such as polyacrylate, polyimide, polyester, etc. can be used.

The thickness of each organic layer is not specifically limited in the present invention. However, the thickness of each organic layer is preferably less than a few microns (μm) to make the flexible CF substrate and the flexible display thinner.

Preferably, the flexible CF substrate 100 according to an embodiment of the present invention may include: a base film 110, which is made of polyimide material and has a thickness of 10 μm to 100 μm; and a separation layer 120, which is made of It is made of polyacrylic acid material and has a thickness of 0.01 μm to 1.0 μm; the protective layer 130 is made of polycycloolefin material and has a thickness of 0.5 μm to 5 μm; the colorant layer 150 has a thickness of 0.5 μm to 5 μm ;and The planarization layer 160 is made of polyacrylic acid material and has a thickness of 0.5 μm to 5 μm.

At the same time, the TFT+OLED substrate 200 has a structure of stacking a base film 210, a TFT layer 220, an OLED layer 230, and an encapsulation layer 240 in a pile. The detailed structure is not specified in the present invention. limit. Furthermore, the TFT+OLED substrate 200 can be manufactured by any method known in the field of flexible display technology.

The patterns of the BM layer 140 and the coloring agent layer 150 of the flexible CF substrate 100 in the flexible display device of the present invention are aligned with the TFT layer 220 and the OLED layer 230 of the TFT+OLED substrate 200 to have a size of 5 μm or less The alignment error is far more accurate than the conventional flexible display device using film-type color filters. Hereinafter, the alignment of the substrate will be described in more detail with respect to the manufacturing method of the flexible display device of the present invention.

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

2 to 11 are cross-sectional views schematically showing the procedure of an embodiment of the method for manufacturing a flexible display device according to the present invention.

The method of manufacturing a flexible display device according to an embodiment of the present invention can generate a high-resolution pattern by executing a process on a carrier substrate. Since the flexible CF substrate formed on the carrier substrate and the TFT+OLED substrate also formed on the carrier substrate are aligned and attached, and then the carrier substrate is separated, the alignment error can be minimized. In addition, there are no restrictions on the materials used for the plastic substrate.

First, as shown in FIG. 2, a first carrier substrate 170 is prepared, a composition for forming a separation layer is applied, and a separation layer 120 is formed.

The first carrier substrate 170 is preferably a glass substrate, but it is not limited thereto. That is, you can use its Other types of materials (if they are heat-resistant materials), these materials can withstand the processing temperature of one of the subsequent processes and maintain flatness without deformation at a high temperature.

The composition for forming a separation layer can be applied by a conventional coating method known in the art. For example, spin coating, die coating, spray coating, roll coating, screen coating, slit coating, dip coating, gravure coating, and the like can be mentioned. Alternatively, an inkjet method can be used.

After coating, the composition for forming a separation layer is subjected to curing by thermal curing or UV curing to form the separation layer 120. Thermal curing and UV curing can be performed individually or in combination. For thermal curing, an oven or hot plate can be used. The heating temperature and time depend on the coating composition, and for example, curing may be performed at 80°C to 250°C for 10 to 120 minutes.

Next, as shown in FIG. 3, a composition for forming a protective layer is applied on the separation layer 120 to form a protective layer 130, which covers the separation layer to the extent of its side surface.

As mentioned above, since the separation layer 120 can be separated by a physical force and its peel strength is very weak, it is preferable to form a protective layer to cover the side surface of the separation layer.

The coating and curing method of the composition for forming the protective layer is similar to the method described above.

Then, as shown in FIGS. 4 and 5, a BM layer 140 is formed on the protective layer 130, and a colorant layer of one of red (R), green (G), blue (B) and white (W) colors 150 is formed in the middle of the pattern of the BM layer 140. That is, the BM layer 140 is first formed on the protective layer 130 to define pixels, and is applied in a predetermined pattern, exposed, developed, and thermally cured to form the coloring agent layer. The color of the colorant layer 150 can be arbitrarily selected, and the color formation order can also be arbitrarily selected.

The coating and curing methods of the BM layer 140 and the coloring agent layer 150 are similar to the methods described above.

At the same time, an alignment key (not shown) for aligning with the TFT+OLED substrate 200 is also formed in the process of forming the BM layer 140.

In addition, the order of forming the BM layer 140 and the coloring agent layer 150 can be changed as needed. That is, you can The colorant layer 150 is patterned first, and then the BM layer 140 is formed.

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

On the other hand, a TFT+OLED substrate 200 shown in FIG. 7 is formed on the second carrier substrate 270 through separate processes from the processes described with respect to FIGS. 2-6. The TFT+OLED substrate 200 can be prepared by any method known in the field of flexible display technology, and it is not specifically limited in the present invention.

The second carrier substrate 270 is preferably a glass substrate, such as the first carrier substrate 170, but it is not limited thereto. That is, other types of materials (if they are heat-resistant materials) can be used, which can withstand one of the processing temperatures for TFT and OLED formation and maintain flatness without deformation at a high temperature.

Furthermore, an alignment key (not shown) for aligning with the CF substrate is formed in the TFT+OLED substrate 200 during any of the manufacturing processes. For example, the alignment key may be formed in a metal layer forming step for forming a wiring.

Next, as shown in FIG. 8, the separation layer 120, the protective layer 130, the BM layer 140, the colorant layer 150, and the planarization layer 160 are formed thereon through the procedures shown in FIGS. 2 to 6 A carrier substrate 170 is aligned with the TFT+OLED substrate 200 formed on the second carrier substrate 270. At this time, the alignment keys in the BM layer 140 formed on the first carrier substrate 170 and the alignment keys in the metal layer of the TFT+OLED substrate 200 are used for alignment, and the alignment accuracy can be 5 μm Or smaller.

The alignment key may be formed at the outermost part of the panel in the cut substrate of the panel or at the outermost part of the glass substrate where a plurality of panels are gathered.

In particular, since the process of manufacturing color filters on the first carrier substrate 170 and the process of manufacturing TFT and OLED arrays on the second carrier substrate 270 are usually performed by separate processes, the predetermined alignment keys are formed separately Align the two substrates at a predetermined position.

In the related art, when a CF substrate formed on a base film as a flexible substrate is attached to a TFT+OLED substrate by a transfer method, the 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 colorant layer 150, and the colorant layer 150 are aligned and formed thereon without separating the first and second carrier substrates 170 and 270. The first carrier substrate 170 of the planarization layer 160 and the TFT+OLED substrate 200 formed on the second carrier substrate 270 (both the first and second carrier substrates 170 and 270 are glass substrates), thereby significantly improving alignment The accuracy. Specifically, the alignment error can be reduced to about 5 μm, which is 1/100 of the related art.

Next, as shown in FIG. 9, the aligned substrates are adhered to each other. An OCA or OCR can be used to perform adhesion. The adhesion of the substrate can be accomplished by any other 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. The first carrier substrate 170 and the second carrier substrate 270 can be separated simultaneously or sequentially, and they can be separated in any order during the sequential separation.

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

Examples of peeling methods may include (not limited to) lift off and peel off.

The peel strength, thickness, and surface energy after separation of the separation layer 120 are the same as the peel strength, thickness, and surface energy after separation described in the detailed description about the structure of the flexible display device according to an embodiment of the present invention. Therefore, the separation layer 120 can be cleanly separated from the carrier substrate without residue, cracks, or curling.

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

The base film 110 is flexible and can be selected to suit the desired purpose among the aforementioned materials.

Although not shown in the drawings, an adhesive layer can be used to adhere the base film 110 to the separation layer 120, and a photo-curable adhesive can be used. Since the photocurable adhesive does not require a separate drying process after photocuring, the process is simple. Therefore, the yield increases. In the present invention, photo-curable adhesives available in this technology can be used without specific limitations. For example, a composition including an epoxy compound or an acrylic monomer can be used.

To cure the adhesive layer, light, such as far ultraviolet, ultraviolet, near ultraviolet, and infrared can be used; electromagnetic waves, such as X-rays, γ-rays, and electron beams, proton beams, and neutron beams can also be used. However, in terms of curing speed, curing device availability, cost, etc., UV curing is advantageous.

A high-pressure mercury lamp, electrodeless lamp, ultra-high pressure mercury lamp, carbon arc lamp, xenon lamp, metal halide lamp, chemical lamp, black light and the like can be used as a light source for UV curing.

Meanwhile, in the above-mentioned embodiments of the present invention, it is described that the TFT+OLED substrate in which the OLED is formed on the TFT and the CF substrate are assembled to form a flexible OLED display device, however, the present invention is not limited to this. For example, when manufacturing a flexible liquid crystal display device by inserting a liquid crystal layer instead of an OLED layer between a TFT array substrate and a CF substrate, the present invention can be used with modifications obvious to those skilled in the art One of the methods for manufacturing flexible display devices.

Although specific embodiments and examples of the present invention have been shown and described, those skilled in the art will understand that the present invention is not intended to be limited to the preferred embodiments, and it will be obvious to those skilled in the art that they can Various changes and modifications are made in accordance with the spirit and scope of the company.

Therefore, the scope of the present invention should be defined by the scope of the attached invention application and its equivalents.

120: separation layer

130: protective layer

140: Black matrix (BM) layer

150: colorant layer

160: Planarization layer

170: first carrier substrate

210: basement membrane

220: Thin film transistor (TFT) layer

230: Organic Light Emitting Diode (OLED) layer

240: encapsulation layer

270: second carrier substrate

Claims (9)

A method of manufacturing a flexible display device includes the following steps: forming a separation layer on a first carrier substrate; forming a protective layer on the separation layer; forming a black matrix layer on the protective layer and A colorant layer is formed in the middle; the first carrier substrate on which the separation layer, the protective layer, the black matrix layer, and the colorant layer are formed and a thin film transistor array substrate are aligned and attached And removing the first carrier substrate, wherein in the aligning and attaching steps, the separation layer, the protective layer, the black matrix layer and the colorant layer are formed on the first The alignment keys on the carrier substrate and the thin film transistor array substrate perform the alignment; and the alignment is performed with an alignment error of 5 μm or less. The method of claim 1, further comprising the step of attaching a flexible base film to a surface of the separation layer from which the first carrier substrate is removed. The method of claim 1, wherein the thin film transistor array substrate includes an organic light emitting diode. The method of claim 1, wherein the thin film transistor array substrate includes a second carrier substrate; and the method further includes a step of removing the second carrier substrate after the alignment and attachment steps. The method of claim 4, wherein the first carrier substrate and the second carrier substrate are removed at the same time. The method of claim 1, wherein the protective layer is formed to cover a side surface of the separation layer. The method of claim 1, wherein the protective layer may include at least one of an organic insulating film and an inorganic insulating film. The method of claim 1, which further includes a step of forming a planarization layer on the black matrix layer and the colorant layer. The method of claim 1, wherein in the alignment and attaching step, an optically clear adhesive or an optically clear resin is used to attach the separation layer, the protective layer, and the black matrix layer formed thereon And the first carrier substrate and the thin film transistor array substrate of the colorant layer.

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