Electronic display device and method for manufacturing the same

Abstract

To economically provide an electronic display device with a narrow frame which can be enlarged by tiling.SOLUTION: The electronic display device includes: a substrate; a polymer film bent to hold the substrate, the polymer film being attached to a first surface and a second surface of the substrate and being resistant to heat of 100°C or higher; a wire formed in a surface of the polymer film which is opposite to the attachment surface of the substrate, the wire extending from the first surface side to the second surface side of the substrate; and an electronic display device formed in the surface of the polymer film which is opposite to the attachment surface of the substrate.SELECTED DRAWING: Figure 13(A)

Description

[Technical field]

[0001] The present invention relates to a narrow-frame electronic display device and a method for manufacturing the same, and in particular to an electronic display device of a type in which a driver IC is mounted on the rear surface of a display panel. Hereinafter, the electronic display device may also be referred to simply as a display device.

[0002] The screen size of liquid crystal displays, OLEDs, self-luminous displays such as micro LEDs, and reflective displays such as electrophoretic displays is constantly increasing. However, the manufacturing of these displays requires large-area microfabrication technology and a highly clean environment, and the construction of manufacturing factories requires huge costs. Even if there is just one defective pixel in the display pixels, it can be a fatal defect in the product, so the yield of displays decreases as the screen size increases. Even if the occurrence frequency of defective pixels is 1 pixel per square meter, if the screen size of an electronic display device is 1 square meter, most of the products will be defective. On the other hand, if the product size is 10 cm square, i.e., 100 cm square, the probability of there being only one defective product out of 100 products is 99 acceptable products.

[0003] In light of this, attempts are being made to realize large-area electronic display devices by tiling small and medium-sized electronic display devices. When tiling, the width of the frame of each electronic display device is important. If the frame is wide, the tiling joints will be noticeable, and the appeal of the large area will be diminished. The width of the frame depends on the arrangement of peripheral devices and parts, such as the driving circuits, mounted on the electronic display device. Generally, the driving circuit elements of a display device (driving ICs, hereafter also referred to as driver ICs or driver elements) are attached to the periphery of the display device using TABs, COFs, etc. A configuration has been proposed in which a TAB or COF using a bendable film base material is folded at the edge of the electronic display device, and the driving circuit is disposed on the side or back surface of the electronic display device (Patent Document 1, Patent Document 2). Recently, a configuration has been proposed in which an electronic display device section is formed on a polymer film, which is folded at the end, and the peripheral circuits, etc. are disposed on the back surface of the electronic display device, thereby making the electronic display device more compact (Patent Document 3, Patent Document 4). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 2987903 [Patent Document 2] Japanese Patent Application Publication No. 10-148839 [Patent Document 3] US Patent Application Publication No. 2018 / 0090702 [Patent Document 4] International Publication No. 2020 / 065910 Summary of the Invention [Problem to be solved by the invention]

[0005] In driver implementation using TAB or COF, it is common to use ACF (anisotropic conductive film) to connect the electrodes formed on the display device to the terminals of the TAB or COF for electrical connection with the electronic display device. In other words, since it is necessary to place electrodes for connection with the TAB or COF on the periphery of the display part of the electronic display device, the frame width cannot be narrower than the electrode width. On the other hand, in the method of producing the display part of the electronic display device on a film substrate and folding the end part to turn it over, after mounting the driver element, it is necessary to carry out processing that deforms the entire electronic display device, which may damage the driver element or the connection part between the driver element and the electronic display device, etc. Furthermore, in order to mount the driver IC after carrying out processing that deforms the electronic display device on the film substrate, the pressure, heat, ultrasonic vibration, etc., that occurs when mounting the driver element are transmitted through the film substrate to the backplane side of the electronic display device, which may destroy the TFT of the electronic display device, which is a particularly delicate part. [Means for solving the problem]

[0006] In order to solve these problems, the inventors conducted intensive research and discovered an electronic display device structure and a manufacturing method thereof that can be manufactured using existing electronic display device manufacturing equipment, has a narrow frame, and can achieve a high yield rate in terms of the implementation of driving circuits, thereby arriving at the present invention.

[0007] That is, the present invention comprises the following: [1] Substrate, a polymer film folded so as to sandwich the substrate and adhered to both the first surface and the second surface of the substrate; an electronic display device formed on a surface of the polymer film attached to the first surface of the substrate; a driving circuit element for an electronic display device mounted on the surface of the polymer film attached to the second surface of the substrate; Wiring formed on the surface of the polymer film, electrically connecting the electronic display device and a driving circuit element; Including, An electronic display device, wherein the outer dimension Lo of the electronic display device and the outer dimension Ld of a display unit of the electronic display device satisfy the following relationship: Lo<(1 / 2)×(Ld+5×Lpx) Here, Lo: External dimensions of electronic display device Ld: External dimensions of the display part of the electronic display device Lpx: pixel size of an electronic display device It is. [2] Substrate, a polymer film having a softening temperature of 150° C. or more and 380° C. or less, which is folded so as to sandwich the substrate and is adhered to both the first surface and the second surface of the substrate; a wiring formed on a surface of the polymer film opposite to a surface bonded to the substrate, the wiring extending from a first surface side to a second surface side of the substrate; an electronic display device formed on the surface of the polymer film opposite to the surface bonded to the substrate; 13. An electronic display device comprising: [3] The electronic display device according to [1] or [2], wherein the polymer film has an elastic modulus of 3 GPa or more and a breaking elongation of 3% or more. [4] The electronic display device according to any one of [1] to [3], wherein the polymer film is a polyimide film having a thickness of 3 μm or more and 75 μm or less. [5] The electronic display device according to any one of [1] to [4], wherein the polymer film is a polyimide film having a total light transmittance of 85% or more and a yellow index of 5 or less. [6] The electronic display device according to any one of [1] to [5], wherein the polymer film and the first surface of the substrate are bonded to each other via a silane coupling agent condensate layer. [7] The electronic display device according to any one of [1] to [6], wherein the polymer film and the second surface of the substrate are bonded to each other via a silane coupling agent condensate layer. [8] The electronic display device according to any one of [1] to [7], wherein the polymer film and the side surface of the substrate are bonded via a silane coupling agent condensate layer. [9] The electronic display device according to any one of [1] to [8], wherein a part or all of the part of the polymer film facing the side surface of the substrate is thinned.

[10] The electronic display device according to any one of [1] to [9], wherein a portion of the polymer film facing the side surface of the substrate is removed.

[11] The electronic display device according to any one of [1] to

[10] , wherein a driving IC for the electronic display device is mounted on the second surface side of the substrate.

[12] (a) preparing a laminate having a substrate and a polymeric film adhered to at least one surface of the substrate; (b) forming an electronic display device and wiring on the polymer film; (c) removing the substrate outside the region in which the electronic display device is formed, and dividing the region into a display region bonded to the substrate and a wiring region from which the substrate has been removed; (d) heating the vicinity of the boundary between the display area and the wiring area to a temperature equal to or higher than the softening point of the polymer film, and bending the wiring area along a side surface of the substrate; (e) The method for producing an electronic display device according to any one of [1] to

[11] , further comprising at least a step of bending the wiring region from a side surface of the substrate towards a rear surface (second surface).

[13] The method for producing an electronic display device according to

[12] , wherein the heating means is light irradiation.

[14] The method for manufacturing an electronic display device according to

[12] , wherein the heating means is direct contact of a heated object.

[15] The method for manufacturing an electronic display device according to

[12] , wherein the heating means is electromagnetic induction heating.

[0008] The present invention preferably further includes the following configuration.

[16] The electronic display device described in any one of [1] to

[11] , characterized in that the radius of curvature of the corner where the polymer film is bent from the first surface of the substrate toward the side surface is no more than three times the sum of the thickness of the polymer film and the thickness of the wiring.

[17] The electronic display device according to any one of [1] to

[11] , wherein the length Lp of the polymer film parallel to the side surface of the substrate is 30% or more of the thickness Ts of the substrate.

[0009] The present invention preferably further includes the following configuration.

[18] The electronic display device according to any one of [1] to

[11] , wherein the wiring has a thickness of 3 μm or less.

[19] The electronic display device according to any one of [1] to

[11] , wherein the wiring is a sintered body of nanometal particles.

[20] The electronic display device according to any one of [1] to

[11] , wherein the wiring contains metal particles and a thermoplastic resin binder.

[21] The method for producing an electronic display device according to any one of

[12] to

[15] , wherein the laminate is a laminate in which a polymer film and a substrate are bonded via a silane coupling agent condensate layer.

[22] The method for producing an electronic display device according to any one of

[12] to

[15] , wherein the laminate is a laminate in which a polymer film and a substrate are bonded with an adhesive.

[23] The method for producing an electronic display device according to any one of

[12] to

[15] , wherein the laminate is obtained by applying a polymer solution to a substrate and drying the applied solution.

[24] The method for producing an electronic display device according to any one of

[12] to

[15] , wherein the laminate is obtained by applying a polymer precursor solution to a substrate, drying and undergoing a chemical reaction.

[25] The method for producing an electronic display device according to any one of

[12] to

[15] , wherein the laminate is obtained by thermocompression bonding a polymer film to a substrate. Effect of the Invention

[0010] According to a first embodiment of the present invention, in an electronic display device, an electronic display device, which is a display unit, is formed on a polymer film that is folded so as to sandwich a substrate and is adhered to both a first surface and a second surface of the substrate, the polymer film is adhered to the substrate, and the outer shape of the display part of the electronic display device is approximately equal to the outer shape of the substrate. Wiring for transmitting a drive signal for the electronic display device is formed on the polymer film, and the wiring is folded together with the polymer film along the side surface of the substrate and adhered to the back side (second surface) of the substrate, and a driving circuit element (hereinafter also referred to as a driver IC) for driving the electronic display device is joined to the wiring on the back side of the substrate. This type of display structure has long been known for the purpose of narrowing the frame width of a display device, but in conventional display devices, the film that is folded from the front side (first surface) of the substrate to the back side (second surface) is a TAB or COF base film, which is separate from the substrate of the electronic display device itself. In the present invention, the display portion of the electronic display device and the lead-out wiring arranged around the electronic display device are formed on a common polymer film substrate. Therefore, there is no terminal portion required for connection as in TAB or COF. Therefore, the lead-out wiring can be bent near the base where it is led out from the display portion, making it possible to narrow the frame of the electronic display device. Furthermore, in the present invention, by using a polymer film having a certain physical property, it is possible to fold the film at an angle close to an acute angle without damaging the wiring and the electronic display device. As a result, the length Lov (1 / 2 × "electronic display outer dimension Lo" - "substrate outer dimension Ld") of the overhanging part of the polymer film protruding from the edge of the substrate can be reduced, making it possible to further narrow the frame.

[0011] According to the second embodiment of the present invention, the structure of the electronic display device of the present invention does not require an electrode region for connecting the TAB or COF to the electronic display device section, so that it is possible to take out the wiring from the very vicinity of the display section of the electronic display device. In addition, since the polymer film supporting the wiring is softened by heating, even if the taken-out wiring is directly bent from the very vicinity of the display section or almost from the side of the display section, the strain caused by the deformation is absorbed by the softening of the polymer film, so that the wiring is less damaged and the thickness of the wiring can be made very thin, preferably 3 μm or less. In addition, since the stress on the wiring can be reduced, a metal film that is relatively difficult to deform can be used as the wiring. For example, it is possible to apply wiring by printed electronics technology such as inkjet printing, reverse printing, and microcontact printing using nano-sized metal particles. In these printed electronics technologies, the wiring is obtained as a low-temperature sintered body of metal fine particles, so it tends to be more fragile than wiring composed of a bulk metal layer, and is not suitable for applications involving bending, but by combining it with the present invention, it is possible to combine it with these new wiring formation technologies. In addition, in the present invention, wiring obtained by printing a conductive paste containing metal particles and a thermoplastic resin binder can be used. Since the binder resin has thermoplasticity, wiring using a conductive paste of such a composition can be thermally deformed together with the polymer film having a softening temperature of the present invention, and since the environment during use is below the softening temperature, the wiring is firmly fixed, and therefore the wiring is prevented from being damaged by vibration, etc. As a result, the frame width of the electronic display device can be effectively narrowed to the thickness of the wiring and polymer film, and the driver IC can be mounted on the back side of the substrate, further reducing space.

[0012] In the present invention, a part or the whole of the polymer film is preferably adhered to the substrate via a silane coupling agent condensate. The presence of the silane coupling agent condensate layer is the result of the silane coupling agent treatment. The thickness of the silane coupling agent condensate layer is extremely thin, and is at a level that can be practically ignored when compared with the thickness of the substrate and the polymer film. Therefore, the flatness of the polymer film layer is almost controlled by the substrate, so that an extremely smooth surface can be obtained. This is an essential characteristic in the formation of electronic display devices that require large-area, high-precision processing. When the polymer film is used without a support (substrate) or is adhered to the substrate with a general adhesive or pressure-sensitive adhesive having a thickness of several μm to several tens of μm, undulations occur on the polymer film surface when the polymer film is folded, and the presence of this undulation can be fatal in microfabrication that requires extremely precise exposure operations.

[0013] The heat resistance of the silane coupling agent condensate layer is higher than that of adhesives made of general organic substances, and can fully withstand high temperature environments in various processes for forming electronic display devices, more specifically, in processes for forming amorphous silicon thin films, polysilicon thin films, oxide semiconductor thin films, compound semiconductor films, etc. Furthermore, it can fully withstand chemicals, solvents, plasma processing, etc. used in processing processes such as exposure, development, etching, and resist peeling. Therefore, the electronic display device of the present invention can directly perform processing required for electronic display devices on the polymer film of the laminate obtained by laminating a polymer film on a substrate via a silane coupling agent condensate layer. According to this processing method, it is possible to treat the flexible film as if it were a single substrate and perform the processing using a conventional electronic display device manufacturing device. The present invention can also be applied to a process in which a solution of a polymer precursor (a typical example is polyamic acid, a precursor of polyimide) is applied to a substrate, and then dried and cured to form a polymer film on the substrate, by precisely controlling the thickness.

[0014] Furthermore, in the present invention, the polymer film, which is the substrate of the electronic display device, is preferably supported by an inorganic substrate such as glass, so that the flatness of the electronic display device is maintained. Furthermore, the lead wiring portion, which is folded from the periphery of the electronic display device and routed to the back of the substrate, can be bonded to the back of the substrate together with the polymer film, which is the base material. Since the polymer film is supported by a hard substrate, it is possible to directly bond the driver IC to the terminal on the polymer film after bonding. When the polymer film does not have a support (substrate) or when the rigidity of the support is low, the bonding accuracy is often reduced. On the other hand, the electronic display device of the present invention makes it possible to obtain high bonding accuracy. Of course, this effect is not limited to inorganic substrates, as long as a substrate having flatness comparable to that of glass and high compressive elasticity is used. [Brief description of the drawings]

[0015] [Figure 1(A)] Fig. 1(A) is a schematic diagram showing a cross-sectional configuration of one embodiment of the electronic display device of the present invention. In the embodiment of Fig. 1(A), polymer films are bonded to both the first and second surfaces of a substrate via a silane coupling agent layer. [Figure 1(B)] Fig. 1(B) is a schematic diagram showing a cross-sectional configuration of one embodiment of the electronic display device of the present invention. In the embodiment of Fig. 1(B), polymer films are bonded to both the first and second surfaces of the substrate via a silane coupling agent layer. [Figure 2(A)] Fig. 2(A) is a schematic diagram showing a cross-sectional configuration of one embodiment of the electronic display device of the present invention. In the embodiment of Fig. 2(A), a first surface of a substrate and a polymer film are bonded via a silane coupling agent layer, and a second surface of the substrate and a polymer film are bonded with an adhesive. [Figure 2(B)] Fig. 2(B) is a schematic diagram showing a cross-sectional configuration of one embodiment of the electronic display device of the present invention. In the embodiment of Fig. 2(B), the first surface of the substrate and the polymer film are bonded via a silane coupling agent layer, and the second surface and the polymer film are bonded with an adhesive. [Figure 3(A)]Fig. 3(A) is a schematic diagram showing a cross-sectional configuration of one embodiment of the electronic display device of the present invention. In the embodiment of Fig. 3(A), a first surface of a substrate and a polymer film are bonded with an adhesive, and a second surface of the substrate and a polymer film are bonded via a silane coupling agent condensate layer. [Figure 3(B)] Fig. 3(B) is a schematic diagram showing a cross-sectional configuration of one embodiment of the electronic display device of the present invention. In the embodiment of Fig. 3(B), the first surface of the substrate and the polymer film are bonded with an adhesive, and the second surface of the substrate and the polymer film are bonded via a silane coupling agent condensate layer. [Figure 4] Fig. 4 is a schematic diagram showing a cross-sectional configuration of one embodiment of the electronic display device of the present invention. In the embodiment of Fig. 4, the first and second surfaces of the substrate, and further the side surface of the substrate and the polymer film are bonded via a silane coupling agent condensate layer. [Diagram 5] Fig. 5 is a schematic diagram showing a cross-sectional structure of one embodiment of the electronic display device of the present invention. In the embodiment of Fig. 5, a polymer film is adhered to both the first and second surfaces of the substrate via a silane coupling agent layer. The polymer film in the portion located on the side surface of the substrate is thinned. [Figure 6] Fig. 6 is a schematic diagram showing the cross-sectional structure of one embodiment of the electronic display device of the present invention. The embodiment of Fig. 6 shows a case where the display portion of the electronic display device is larger than the size of the substrate. [Figure 7] Fig. 7 is a schematic diagram showing a cross-sectional structure of one embodiment of the electronic display device of the present invention. In the embodiment of Fig. 7, a gap exists on the side surface of the substrate. [Figure 8] FIG. 8 is a diagram illustrating the first half of an example of a manufacturing process for the electronic display device of the present invention when a film lamination method is used. [Figure 9(A)] FIG. 9A is a diagram illustrating the latter half of an example of the manufacturing process for the electronic display device of the present invention when a film lamination method is used. [Figure 9(B)] FIG. 9B is a diagram illustrating the latter half of an example of the manufacturing process for the electronic display device of the present invention when a film lamination method is used. [Figure 10]FIG. 10 is a diagram illustrating the first half of an example of a manufacturing process for an electronic display device of the present invention when a varnish method is used. [Figure 11(A)] FIG. 11A is a diagram illustrating the latter half of an example of the manufacturing process for the electronic display device of the present invention when the varnish method is used. [Figure 11(B)] FIG. 11B is a diagram illustrating the latter half of an example of the manufacturing process for the electronic display device of the present invention when the varnish method is used. [Figure 12] FIG. 12 is a schematic diagram showing a case where a driver IC is mounted using a conventional TAB. [Figure 13(A)] 13(A) is a schematic diagram showing the details of the side portion of the electronic display device of the present invention, with the silane coupling agent layer, adhesive layer, and driver IC omitted. [Figure 13(B)] 13(B) is a schematic diagram showing the details of the side surface of the electronic display device of the present invention, with the silane coupling agent layer, adhesive layer, and driver IC omitted. [Figure 14] FIG. 14 is a schematic diagram showing the details of the side portion of the electronic display device of the present invention, showing the state when the gap portion is filled with resin. [Figure 15] FIG. 15 is a schematic diagram showing details of a side portion of an electronic display device of the present invention, showing a state in which there is substantially no gap. [Figure 16] FIG. 16 is a schematic diagram showing the details of the side portion of the electronic display device of the present invention, in which there is essentially no gap, and furthermore, the portion of the polymer film located on the side of the substrate has been removed, and the wiring has been made into a flying lead. [Figure 17] FIG. 17 is a schematic diagram showing details of the side portion of the electronic display device of the present invention, in which there is essentially no gap, the polymer film located on the side of the substrate is removed, the wiring is made into flying leads, and the dimensions of the display portion of the electronic display device are larger than the dimensions of the substrate. [Figure 18] FIG. 18 is a schematic diagram showing a case where a driver IC is mounted using a conventional TAB. [Figure 19] FIG. 19 is a schematic diagram showing the configuration of a side portion of one example of an electronic display device that has been proposed in the past. [Figure 20] Fig. 20 is a schematic diagram showing the shape of the side portion of one example of a conventionally proposed electronic display device. A large gap exists between the side surface of the substrate and the polymer film, which prevents the frame from being narrowed. [Figure 21] FIG. 21 is a layout diagram of a simulated display device used in an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] The present invention will now be described in detail with reference to the drawings. Figures 1(A) and 1(B) are schematic diagrams showing the cross-sectional configuration of a representative embodiment of an electronic display device of the present invention. Substrate 15 is the key element that supports the entire electronic display device of the present invention. As the substrate, organic substrates such as polymer plates and polymer sheets, composite substrates such as glass fiber reinforced resin substrates, inorganic filler reinforced resin substrates, and carbon fiber reinforced resin substrates, glass substrates, metal substrates, metal foils, silicon wafers, and other inorganic substrates such as semiconductor wafers can be used. For practical purposes, flat substrates can be used. Flexible glass having a thickness of about tens of μm can also be used as the substrate. The preferred thickness of the inorganic substrate 15 is 20 μm or more, more preferably 45 μm or more, and even more preferably 300 μm or more. In addition, it is preferably 5 mm or less, more preferably 1.2 mm or less, and even more preferably 0.7 mm or less. By setting the thickness of the inorganic substrate within the above range, durability and handling properties are improved. Glass substrates include quartz glass, high silicate glass (96% silica), soda-lime glass, lead glass, aluminoborosilicate glass, borosilicate glass (Pyrex (registered trademark)), borosilicate glass (alkali-free), borosilicate glass (microsheet), aluminosilicate glass, etc. Among these, those with a linear expansion coefficient of 5 ppm / °C or less are preferable, and commercially available products such as liquid crystal glass "Corning (registered trademark) 7059", "Corning (registered trademark) 1737", and "EAGLE" manufactured by Corning Incorporated, "AN100" manufactured by Asahi Glass Co., Ltd., "OA10" manufactured by Nippon Electric Glass Co., Ltd., and "AF32" manufactured by SCHOTT are preferable. Furthermore, these inorganic substrates, preferably substrates having a thin film formed on the surface thereof, of metals such as chromium, nickel, nichrome, molybdenum, and tungsten, metal oxides, metal nitrides, silicon nitride, aluminum nitride, and silicon carbide, may also be used. Also usable are metal substrates or metal foils having an anodized film formed on the surface, and inorganic substrates having a fluororesin coating or silicone resin coating. Examples of resins that can be used for the organic substrate and composite substrate include epoxy resin, polyimide resin, phenol resin, melamine resin, crosslinked polyester resin, polyether ether ketone resin, bismaleimide triazine resin, and crosslinked acrylic resin.

[0017] <Polymer film> The polymer film 30 can be made of films such as polyethylene, polypropylene, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, wholly aromatic polyester, other copolymer polyesters, polymethyl methacrylate, other copolymer acrylates, polycarbonate, polyamide, polysulfone, polyethersulfone, polyetherketone, polyamideimide, polyetherimide, aromatic polyimide, alicyclic polyimide, fluorinated polyimide, cellulose acetate, cellulose nitrate, aromatic polyamide, polyvinyl chloride, polyphenol, polyarylate, polyphenylene sulfide, polyphenylene oxide, polystyrene, and liquid crystal polymer.

[0018] The softening temperature of the polymer film of the present invention is preferably 150° C. or higher and 380° C. or lower. Here, the softening temperature is the glass transition temperature obtained by measuring the thermal viscoelasticity. The softening temperature (glass transition temperature) of the polymer film of the present invention is preferably 165° C. or higher, more preferably 180° C. or higher. The upper limit of the softening temperature (glass transition temperature) is preferably 360° C., more preferably 345° C. The present invention includes a process of softening and bending the polymer film by heating, so the polymer film is required to have a softening temperature in a range that allows thermal deformation. On the other hand, since the formation of an electronic display device also requires a process that requires high temperatures, a certain level of heat resistance is required. Among these polymer films, the present invention prefers polymer films obtained by condensation polymerization reaction (condensation polymer films). Particularly effective and useful in the present invention are polymers having heat resistance of 100°C or higher, preferably 150°C or higher, so-called engineering plastic films. Here, heat resistance refers to the property of having a glass transition temperature or heat distortion temperature of 100°C or higher (preferably 150°C or higher). Condensation polymerization polymer films (condensation polymer films) preferably used in the present invention are polyester, polyamide, polyamideimide, polyimide, polybenzazole, polyimidebenzazole, polyethylene naphthalate film, and liquid crystal polymer film, and more preferably polyimide film, polyethylene naphthalate film, or liquid crystal polymer film.

[0019] The polymer films preferably used in the present invention are polyimide films, polyamide films, polyamideimide films, polybenzoxazole films, and polyimidebenzoxazole films, and aromatic polyimides, alicyclic polyimides, polyamideimides, polyetherimides, etc. can be used. When the present invention is used particularly for manufacturing a flexible display element, it is preferable to use a colorless and transparent polyimide-based resin film, but this is not particularly limited when forming a rear element of a reflective or self-luminous display.

[0020] In general, a polyimide film is obtained by applying a polyamic acid (polyimide precursor) solution obtained by reacting diamines with tetracarboxylic acids in a solvent onto a support for producing a polyimide film, drying the solution to form a green film (also called a "precursor film" or "polyamic acid film"), and then subjecting the green film to high-temperature heat treatment on the support for producing a polyimide film or after being peeled off from the support to cause a dehydration ring-closing reaction. Examples of polyimide films preferably used in the present invention include polyimide films obtained from polyimide resins having the following chemical composition. Polyimide resin obtained from pyromellitic acid and diaminodiphenyl ether, Polyimide resin obtained from biphenyltetracarboxylic acid and phenylenediamine, Polyimide resin obtained from pyromellitic acid and phenylenediamine, Polyimide resins using diamine compounds having a benzoxazole skeleton as the diamine component, Polyimide resins using cyclohexyltetracarboxylic acid and cyclobutanetetracarboxylic acid, Polyimide resin using alicyclic tetracarboxylic acid and aromatic diamine with amide bond Polyimide resins using monomers containing fluorine, Polyimide resin using monomers containing ions These are examples of the main components of the tetracarboxylic acid or diamine, respectively, and it is also possible to use polyimide resins copolymerized by blending a second or third component, polyimide resins polymerized by combining polyimides of multiple compositions, polyimide resins polymer blended or alloyed, and polyimide resins into which inorganic fillers or polydimethylsiloxane components have been introduced. It is also possible to use polyimide films having a structure in which polyimide resins of different compositions are laminated in the thickness direction.

[0021] In the present invention, it is preferable to use a polyimide film having an elastic modulus of preferably 3 GPa or more, more preferably 4 GPa or more, even more preferably 5 GPa or more, and preferably 15 GPa or less, even more preferably 12 GPa or less, as the polymer film. If the elastic modulus is within this range, bending at the edge of the substrate is possible, and damage to the wiring can be minimized. If the elastic modulus is lower than this range, the polymer film may be significantly deformed when bending, which may cause disconnection of the wiring. On the other hand, if the elastic modulus is too high, bending may be difficult. The polymer film of the present invention is preferably a polyimide film having a breaking elongation of 3% or more, preferably 5% or more, more preferably 7% or more, and even more preferably 9% or more. The breaking elongation is also a measure of foldability, and if the breaking elongation is low, the film is brittle and easily cracked, so that cracks may occur when the film is bent, but if the breaking elongation is 5% or more, the film can be bent. Furthermore, the polymer film of the present invention is preferably a polyimide film having a thickness of 3 μm to 75 μm. The film thickness is preferably 6 μm or more, and more preferably 12 μm or more. The upper limit is preferably 60 μm, and more preferably 45 μm or less. The film thickness is related to the foldability, and if it is within a certain range, folding becomes relatively easy. Furthermore, the linear expansion coefficient of the polymer film of the present invention is 35 ppm / K or less, preferably 18 ppm / K or less, more preferably 9 ppm / K or less. The lower limit of the linear expansion coefficient is -5 ppm / K, preferably -2 ppm / K. Furthermore, it is preferable that the difference in the linear expansion coefficient between the polymer film and the substrate is 10 ppm / K or less. By keeping the linear expansion coefficient within a predetermined range, warping of the laminate is suppressed and the defective rate during production is reduced.

[0022] In the present invention, the storage modulus of the polymer film at 30°C measured using a heating viscoelasticity measurement method (DMA) is 1.0 x 10 9 Pa or more, and the storage modulus at 300°C is 3.0×10 8 It is preferable to use one that exhibits a modulus of elasticity of less than Pa. Polymer films that fall within this range can be judged to be in the category of thermoplastic.

[0023] In the present invention, in order to fold the polymer film along the side surface of the substrate without stress, it is preferable to adjust the compressive strength of the polymer film to be weaker than the tensile strength of the polymer film. Specifically, for example, voids may be intentionally formed in the polymer film to make it more likely to buckle under compressive stress.

[0024] In the present invention, the polymer film is preferably a polyimide film having a total light transmittance of 85% or more and a yellow index of 5 or less. The total light transmittance is preferably 88% or more, more preferably 91% or more. There is no particular upper limit, but 99% or more is sufficient for use in electronic display devices, and 98% or less is also acceptable. The yellow index is preferably 4 or less, more preferably 3 or less. This means that the polyimide film has colorless transparency. There is no particular lower limit for the yellow index, but 1 or more is sufficient for use in electronic display devices. When a polyimide film having colorless transparency is used, the present invention can be applied to liquid crystal electronic display devices, which are light-transmitting display systems.

[0025] In a preferred method for producing the electronic display device of the present invention, a laminate in which a substrate and a polymer film are bonded together is obtained during the process. Examples of techniques for obtaining such a laminate include a film lamination method and a varnish method.

[0026] <Film lamination method> A polymer film and a substrate are bonded together with an adhesive or a pressure sensitive adhesive to obtain a laminate. Epoxy adhesives, silicone adhesives, acrylic adhesives, and pressure sensitive adhesives can be used as adhesives. However, when a high temperature process is applied to the formation of an electronic display device, it is necessary to use a highly heat resistant adhesive. Furthermore, in the present invention, a method of bonding a substrate and a polymer film via a silane coupling agent condensate can be used as a highly heat resistant bonding method. When high temperatures are required to form an electronic display device, the substrate is also required to be heat resistant, so it is preferable to use it in combination with an inorganic substrate, preferably a glass substrate. In the adhesion method using a silane coupling agent, the silane coupling agent is applied to either or both of the adhesive surfaces of the polymer film or the substrate, and the two are then superimposed and heated. The organic group of the silane coupling agent reacts with the polymer film surface, and the methoxy group and ethoxy group of the silane coupling agent react with the hydroxyl group on the inorganic substrate surface, and the silane couplings self-condense to form a condensate layer, thereby performing adhesion. In this method, for example, by combining with the technology disclosed in Patent Publication No. 5224011, it is possible to control the adhesive strength and form a pattern of parts with strong and weak adhesive strength, and it can be applied in situations where the substrate and the polymer film are partially peeled off.

[0027] <Varnish method> This method involves applying a resin solution that constitutes a polymer film or a polymer precursor solution to a substrate, drying it on the substrate, and carrying out a chemical reaction as necessary to obtain a polymer film. A typical example is the use of a polyimide resin solution or a solution of polyamic acid, which is a polyimide precursor, to obtain a polyimide film. In the varnish method, for example, using the technique disclosed in Japanese Patent No. 5,862,866, it is possible to control the adhesive strength between the substrate and the polymer film and form a pattern of areas with strong and weak adhesive strength.

[0028] The properties of the polymer film specified in the present invention were determined by the following methods. <Substrate thickness, polymer film thickness> The thickness of the polymer film was measured using a micrometer ("Millitron 1245D" manufactured by Fine Leaf Co., Ltd.) and the average value of 10 points was calculated.

[0029] <Tensile modulus, tensile strength at break and tensile elongation at break of polymer film> From the polymer film to be measured, rectangular test pieces measuring 100 mm x 10 mm in the machine direction (MD) and width direction (TD) were cut out, and the tensile modulus, tensile breaking strength, and tensile breaking elongation were measured in each of the MD and TD directions using a tensile testing machine (Shimadzu Corporation, "Autograph (registered trademark); model name AG-5000A") at a tensile speed of 50 mm / min and a chuck distance of 40 mm, and the average value of all the measured values ​​in the MD and TD directions was obtained.

[0030] <Glass transition temperature of polymer film: Heat viscoelastic method> The glass transition temperature was measured by measuring a polymer film (e.g., polyimide film) of 5 mm x 20 mm size using a dynamic viscoelasticity measuring device (DMA: manufactured by UBM, product name: E4000F) from 30°C to 400°C at a heating rate of 4°C / min and a frequency of 1 Hz, and the temperature at which the change in elastic modulus (mechanical tan δ) was maximum was defined as the glass transition temperature.

[0031] <Coefficient of linear expansion (CTE) of polymer film> The expansion / contraction rate was measured under the following conditions for the machine direction (MD) and width direction (TD) of the polymer film to be measured, and the expansion / contraction rate / temperature was measured at 15°C intervals (30°C to 45°C, 45°C to 60°C, ...). This measurement was performed up to 300°C, and the average value of all the measured values ​​in the MD and TD directions was calculated as the coefficient of linear expansion (CTE). Device name: MAC Science "TMA4000S" Sample length: 20mm Sample width: 2mm Heating start temperature: 25℃ Heating end temperature: 400℃ Heating rate: 5℃ / min Atmosphere: Argon Initial load; 34.5g / mm 2

[0032] <Total light transmittance> The total light transmittance (TT) of the film was measured using a HAZEMETER (NDH5000, manufactured by Nippon Denshoku Co., Ltd.). A D65 lamp was used as the light source. The same measurement was performed three times, and the arithmetic average value was used.

[0033] <Yellow Index> Using a color meter (ZE6000, Nippon Denshoku) and a C2 light source, the tristimulus values ​​XYZ of the film were measured according to ASTM D1925, and the yellowness index (YI) was calculated according to the following formula. The same measurement was performed three times, and the arithmetic average value was used. YI=100×(1.28X-1.06Z) / Y

[0034] <Silane coupling agent condensation product layer> The silane coupling agent condensate layer 20 is literally a layer made of a condensate of a silane coupling agent. The silane coupling agent layer functions to bond the substrate and the polymer film. A part or the whole of the adhesive surface of the polymer film and the substrate is bonded via the silane coupling agent condensate layer. The silane coupling agent condensate layer is preferably present on the first surface and / or the second surface of the substrate, and more preferably present on the first surface and the second surface of the substrate. It is further preferable that the silane coupling agent condensate layer is present on the whole of the first surface and the whole of the second surface of the substrate. It is also preferable that the polymer film and the side surface of the substrate are bonded via the silane coupling agent condensate layer. Silane coupling agents are a general term for compounds that make inorganic surfaces organic through a dealcoholization condensation reaction between hydroxyl groups present mainly on inorganic surfaces and methoxy groups, ethoxy groups, etc. contained in the molecules of the silane coupling agents. Such dealcoholization reactions also occur between silane coupling agents, resulting in a condensation product in which the silane coupling agents are linked by siloxane bonds.

[0035] In the present invention, the silane coupling agent is preferably a compound containing 10% by mass or more of Si (silicon).Furthermore, it is preferable that the silane coupling agent has an alkoxy group in the structure.Specific examples of the silane coupling agent that can be preferably used in the present invention include N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-triethoxysilyl-N-(1,3-dimethyl-butylidene)propylamine, N-phenyl-3-aminopropyltrimethoxysilane, N-(vinylbenzyl)-2-aminoethyl-3-aminopropyltrimethoxysilane hydrochloride, aminophenyltrimethoxysilane, aminophenethyltrimethoxysilane, aminophenylaminomethylphenethyltrimethoxysilane, etc.

[0036] Among the above-mentioned silane coupling agents, silane coupling agents having one silicon atom in one molecule are particularly preferred, such as N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-triethoxysilyl-N-(1,3-dimethyl-butylidene)propylamine, aminophenyltrimethoxysilane, aminophenethyltrimethoxysilane, aminophenylaminomethylphenethyltrimethoxysilane, etc. When particularly high heat resistance is required in the process, it is desirable to use one in which Si and amino group are connected by an aromatic group. In addition to the above, 11-amino-1-undecenethiol can also be used as the above-mentioned coupling agent.

[0037] Silane coupling agents are generally liquids, and are applied to a substrate or polymer film to obtain a layer by a gas-phase application method such as wet coating or vapor deposition. As a method for wet-coating the silane coupling agent, a stock solution of the silane coupling agent or a solution diluted with a solvent such as an alcohol solution or an aqueous solution can be used appropriately using a conventionally known solution application means (conventionally known application device) such as a spin coating method, curtain coating method, dip coating method, slit die coating method, gravure coating method, bar coating method, comma coating method, applicator method, screen printing method, or spray coating method. In addition, the silane coupling agent can be spot-applied using a dispenser, a dropper, or a brush.

[0038] The silane coupling agent layer can also be applied through a gas phase, such as by a vapor deposition method. Specifically, the substrate or polymer film is exposed to the vapor of the silane coupling agent, i.e., the silane coupling agent is substantially in a gaseous state, to form the layer. The vapor of the silane coupling agent can be obtained by heating the liquid silane coupling agent to a temperature of 40°C to the boiling point of the silane coupling agent. The boiling point of the silane coupling agent varies depending on the chemical structure, but is generally in the range of 100 to 250°C. However, heating to 200°C or higher is not preferred because it may cause a side reaction on the organic group side of the silane coupling agent. The silane coupling agent may also be applied to both sides of the substrate or polymer film.

[0039] <Wiring> The wiring 40 of the present invention is formed on the surface of the polymer film 30 opposite to the surface bonded to the substrate 15, and is a wiring that reaches from the first surface side to the second surface side of the substrate, and is preferably a wiring that electrically connects (contacts) the electronic display device and the driving element (driver IC). The wiring is actually laid out like a mesh inside the electronic display device and has a multi-layer wiring structure, but for convenience, the figure shows only the part arranged from the peripheral part of the electronic display device to the outer periphery of the electronic display device. In principle, the wiring is preferably a metal layer, and mainly copper, silver, aluminum, gold, silver, nickel, chromium, tin, lead, etc., which have high conductivity, or molybdenum, tungsten, etc., which have low linear expansion coefficients, are used. Furthermore, alloys such as brass, cupro-nickel, bronze, invar, stainless steel, and solder may be used as necessary. Such wiring is formed by vacuum metallizing techniques such as deposition and sputtering, wet metallizing techniques such as electroless plating, or metallizing techniques such as plasma spraying, either alone or in combination. Furthermore, the wiring is patterned by etching or a masking method. Although omitted in the drawings for simplification, the wiring is preferably insulated and protected by resin etc. The upper, lower and side surfaces of the wiring are preferably insulated and protected.

[0040] <Driver circuit element (driver IC)> The driving circuit element (driver IC) 50 of the electronic display device is an integrated electronic circuit element that supplies image signals and power to the electronic display device. The driver IC may be a conventional semiconductor element, and is preferably mounted in the form of a bare chip. The driver IC 50 is preferably mounted on the surface opposite to the electronic device 60, and in FIG. 1, is mounted (mounted) on the surface of the polymer film on the side bonded to the second surface of the inorganic substrate. Although omitted in the figure, in the case of face-down bonding, bumps for connection are formed on the electrode parts extending from the wiring. In the case of face-up bonding, a surface treatment suitable for wire bonding is applied to the wiring. A method of bonding the wiring in a TAB style as a flying lead can also be used. It is a preferred embodiment to perform gold plating, tin plating, or the like as a surface treatment of the wiring. In addition, after mounting the driver IC, an underfill agent, an overcoat, or a pod sealing may be applied.

[0041] <Electronic display device> The electronic display device 60 in the present invention refers to electronic display devices generally called FPD (flat panel display), such as liquid crystal display devices, OLEDs (organic electroluminescence elements), micro LED arrays, and electrophoretic displays, and is the part that displays images in the electronic display device of the present invention. It does not include CRTs (cathode ray tubes). In principle, it can also be applied to FEDs, PDPs, fluorescent display tubes, and the like. The present invention is preferably combined with a large-area technology using tiling, and is preferably combined with a self-luminous OLED, micro LED array, or a reflective display device such as an electrophoretic electronic display device or a reflective liquid crystal display device. The electronic display device 60 is preferably formed on the surface opposite to the driver IC 50, and in Fig. 1, is formed on the surface opposite to the adhesion surface (non-adhesion side) of the polymer film adhered to the first surface of the inorganic substrate. In other words, it is preferably constructed on the surface of the polymer film. Generally, an electronic display device is composed of a backplane and a frontplane. The following process is exemplified as an example of the formation of an electronic display device in the present invention. First, a gas barrier film, an anchor layer, etc. are formed as necessary on the surface of the non-adhered side of a polymer film adhered to a substrate, and then thin-film semiconductor elements and pixel drive electrodes that directly handle each pixel signal are formed, and light-emitting bodies or electrophoretic bodies are arranged. After that, a frontplane equipped with a facing electrode or a color filter as necessary is formed in a build-up manner, or a separately prepared frontplane is attached to obtain an electronic display device. As is well known, an electronic display device is a collection of individual pixels. In this invention, the pixel dimension of an electronic display device (hereinafter also referred to as pixel size or pixel dimension) is defined as Lpx. The pixel dimension can be calculated by dividing the dimension of the electronic display device in either the X or Y direction by the number of pixels constituting the same direction. When three pixels of RGB colors exist in one pixel for color display, RGB are counted as one pixel. In a reflective display, for example, when four colors of YMCK exist in one pixel, YMCK are counted together as one pixel.

[0042] <Adhesive layer> In the present invention, when it is necessary to bond the polymer film and the substrate without using a silane coupling agent, they may be bonded with an adhesive to form the adhesive layer 70. As the adhesive, it is preferable to use an adhesive having relatively high heat resistance, such as an epoxy resin-based or silicone resin-based adhesive that is commonly used in the electronics field. In the present invention, the adhesive preferably has a Si (silicon) content of less than 10 mass %. Furthermore, it is preferable that the adhesive does not have an alkoxy group in its structure.

[0043] <Casting resin> When a gap exists between the side of the substrate and the polymer film on the side of the electronic display device of the present invention, the gap is filled with the casting resin 90, thereby fixing the polymer film located on the side of the substrate and indirectly protecting the wiring formed on the polymer film. Epoxy resin, acrylic resin, silicone resin, urethane resin, phenolic resin, melamine resin, etc. can be used as the casting resin.

[0044] A process for producing the electronic display device of the present invention using a film lamination method will be described with reference to FIG. 8, FIG. 9(A) and FIG. 9(B). Step A in FIG. 8 shows substrate 15 before processing. Step B in Fig. 8 shows a state in which a silane coupling agent condensate layer 20 is formed on the surface of the substrate 15. However, the silane coupling agent is not completely condensed in this state. At this stage, a preliminary treatment for forming a pattern of strong and weak adhesive strength as described in Japanese Patent No. 5224011 can be added. Step C in Fig. 8 shows a state in which a polymer film 30 is further adhered. The adhesive surface of the polymer film is preferably chemically activated by plasma treatment or the like, that is, in a state in which functional groups with high chemical activity such as carboxyl groups, hydroxyl groups, amino groups, and carbonyl groups are present. The organic portion of the silane coupling agent reacts with such functional groups, and the methoxy and ethoxy groups of one of the silane coupling agents react with hydroxyl groups on the surface of the substrate while undergoing a dealcoholization reaction, thereby adhering the two. The silane coupling agents also condense with each other to form a condensate layer. Steps A to C correspond to "(a) a step of preparing a laminate having a substrate and a polymer film adhered to at least one surface of the substrate." In step D of Fig. 8, wiring is formed on the polymer film. For convenience, only the peripheral portion is shown. In step E of Figure 8, the electronic display device is formed. The wiring is actually a mesh within the electronic display device. Processes D and E correspond to "(b) a process of forming an electronic display device and wiring on a polymer film."

[0045] In step F of FIG. 8, a part of the substrate corresponding to the wiring region is removed, and this step divides the laminate into a display region X1 and a wiring region X2. More precisely, it is preferable to remove the substrate so that the dimensions of the display area of ​​the electronic display device are the same as the dimensions of the remaining substrate, or the substrate dimensions are smaller than the dimensions equivalent to the thickness of the substrate. This results in a polymer film that will become the wiring region surrounding the electronic display device in a frame-like shape. To remove a specific portion of the substrate, the substrate may be cut mechanically or by laser irradiation, or a notch may be created and then the substrate may be divided. In the case of a metal substrate, the relevant portion may be removed by etching. In theory, the unnecessary portion may be dissolved and removed even in the case of a substrate by using a strong alkali or hydrofluoric acid. This step F corresponds to "(c) a step of removing the substrate outside the area in which the electronic display device is formed, and dividing the area into a display area bonded to the substrate and a wiring area from which the substrate has been removed."

[0046] First, the latter half of the manufacturing process for an electronic display device using the film lamination method will be described with reference to Fig. 9(A). Step G1 in Fig. 9(A) shows a state in which a slit 31 is made in the polymer film surrounding the periphery of the electronic display device from the side opposite the side with the wiring. The slit can be made half-cut-like, up to the middle of the polymer film or up to the boundary between the polymer film and the wiring. For convenience, the slit is drawn at an acute angle in the figure, but if a slit with an opening of 90 degrees is made, it will be possible to bend the polymer film at a right angle at the slit. Step G2 in Fig. 9(A) shows a state where a thinning process is carried out from the side opposite to the wiring side of the polymer film surrounding the electronic display device. When thinning, it is preferable to thin the polymer film by 90% or less, more preferably 60% or less, and even more preferably 30% or less. It is also preferable to thin the polymer film by 1% or more, more preferably 5% or more, and even more preferably 10% or more. Step G1 or step G2 is performed to enable bending the polymer film at an acute angle and to minimize damage to the wiring when bending the polymer film. Either one of the slit formation and the thinning may be performed, or both may be used in combination as appropriate. In addition, when the polymer film has thermoplasticity, it is also possible to bend the polymer film by heating the polymer film part, preferably locally, to a temperature above the heat distortion temperature, and the polymer film can be bent without applying stress to the wiring portion even without the slits or thinning. Step H in Figure 9(A) shows the case where the wiring is thinned by step G2. The silane coupling agent 21 is applied in advance to the second surface (rear surface) of the substrate where the folded polymer film comes into contact. In this case, a dispenser or the like can be used to apply the required amount to the required locations. In a laboratory setting, it is also possible to apply the agent using a dropper or paintbrush. 9(A) shows a state in which the polymer film is folded and the corresponding portion of the polymer film is bonded to the second surface (rear surface) of the substrate via a silane coupling agent layer. In this case, as in steps A to C, the reaction of the silane coupling agent bonding the substrate and the polymer film and the self-condensation reaction proceed simultaneously in parallel to form a silane coupling agent layer. J in FIG. 9A shows a state in which a drive circuit element (driver IC) for an electronic display device is mounted.

[0047] In this manner, an electronic display device having thinned wiring on the side surface as shown in FIG. 5 can be obtained. If the thinning process corresponding to step G2 is not performed, the shape will be as shown in Fig. 1(A). Even if two 90-degree slits are made, the shape will be as shown in Fig. 1(A) in schematic diagram form. Although the example shown here shows a case in which the polymer film is adhered to the inorganic substrate and the electronic display device portion is not peeled off from the inorganic substrate, but the inorganic substrate portion used in production is incorporated into the electronic display device, it is also possible to peel off the entire polymer film from the inorganic substrate at the stage where the process has progressed to step E, and re-adhere it to a newly prepared substrate of a prescribed size before proceeding to step F. From the viewpoint of suitability for the manufacturing process, it is preferable to use a highly heat-resistant inorganic substrate for the manufacture of electronic display devices, but when a lightweight and flexible product is required, one possible embodiment is to use a lighter and thinner substrate such as a polymer plate, polymer sheet or FRP plate. Figure 2 shows the case where an adhesive is used instead of a silane coupling agent in steps H to I of Figure 9(A). When a silane coupling agent is used to bond the second surface of the inorganic substrate to the polymer film, the silane coupling agent layer is extremely thin, so the polymer film is in effect directly supported by the inorganic substrate, which can be considered a rigid body. Therefore, the only elastic layer that supports the wiring is the polymer film layer, and the heat, pressure, and ultrasonic vibrations during bonding are not absorbed more than necessary, resulting in bonding with a low defect rate. On the other hand, when an adhesive is used, the elastic layer is made up of two layers, a polymer film and an adhesive layer, and ultrasonic vibration during bonding tends to be easily attenuated. However, in the case of Fig. 2(A), the polymer film of the display element part and the inorganic substrate are bonded on the first surface side of the inorganic substrate with a very thin silane coupling agent layer, so that attenuation of ultrasonic vibration is suppressed for the entire device, and it is possible to ensure a sufficiently high bonding yield rate. However, when an adhesive is used, it is preferable to apply it as thinly as possible and to use an adhesive that exhibits a high elastic modulus as a cured product.

[0048] Figure 3(A) shows a case where a polymer film is bonded to an inorganic substrate using an adhesive instead of a silane coupling agent in process B. In this case, contrary to Figure 2(A), vibration absorption occurs due to the adhesive layer occupying a wide area for the entire display device. However, since the adhesive layer directly below where bonding is performed is a very thin silane coupling agent layer, it is possible to ensure a sufficiently high bonding yield rate, as in the case of Figure 2(A). Fig. 4 shows a state in which the side portions of the polymer film and the inorganic substrate are also bonded with a silane coupling agent condensate. When tiling the electronic display devices obtained by the present invention, the side portions of the display devices are easily damaged, so it is a preferred embodiment to reliably bond and fix the side portions to the inorganic substrate. If the flying lead of step G in Fig. 9(A) is not performed, and a silane coupling agent is also applied to the side portions of the inorganic substrate in step H, and the polymer film is folded so as to fit the side portions of the inorganic substrate, the configuration of Fig. 4 can be realized.

[0049] Next, the latter half of the manufacturing process for an electronic display device using the film lamination method will be described with reference to Fig. 9(B). In step G of Fig. 9(B), a silane coupling agent or a solution 21 of a silane coupling agent is applied to a part or all of the back side (second surface) of the remaining substrate. In this case, a dispenser or the like can be used to apply the required amount to the required location. In a laboratory setting, it is also possible to apply the agent using a dropper or paintbrush. When a solution is used, a silane coupling agent film is formed by drying. Prior to this, a portion of the surface of the polymer film that was attached to the substrate in the wiring region may be thinned by plasma etching, sandblasting, other mechanical grinding methods, chemical etching, or the like. In step H of Fig. 9(B), the part of the polymer film in the wiring area adjacent to the display area is heated, and then the polymer film together with the wiring is folded along the side (cut surface) of the substrate, and further folded toward the back side (second surface) of the substrate. This process corresponds to "(d) a process of heating the vicinity of the boundary between the display area and the wiring area to above the softening point of the polymer, and folding the wiring area along the side of the substrate, and (e) a process of further folding the wiring area from the side of the substrate toward the back surface (second surface)." A silane coupling agent 21 is applied in advance to the second surface (rear surface) of the substrate, and the polymer film is adhered to the substrate by condensation of the silane coupling agent, and by reaction between the polymer film and the silane coupling agent, and between the substrate and the silane coupling agent. The means for heating the polymer film can be appropriately selected from the following: irradiation with ultraviolet light, infrared light, laser light, or a strong flash lamp; direct contact with a heated object; heating by radiant heat by bringing a heated object close to the film; heating the wiring itself by electromagnetic induction; and heating using microwaves. The heating temperature is preferably within the range of the softening temperature of the polymer film to the softening temperature + 80°C. Step I in Fig. 9(B) shows a state in which the polymer film is folded and the corresponding portion of the polymer film is bonded to the second surface (rear surface) of the substrate via a silane coupling agent layer. Note that although a silane coupling agent is used here as an example, an adhesive may be used instead of the silane coupling agent. J in FIG. 9B shows the state in which a drive circuit element (driver IC) for an electronic display device is mounted.

[0050] As a result of the above, an electronic display device having a side surface as shown generally in FIG. 1(B) and specifically in FIG. 13(B) can be obtained. Although the example shown here shows a case in which the polymer film is adhered to the inorganic substrate and the electronic display device portion is not peeled off from the inorganic substrate, but the inorganic substrate portion used in production is incorporated into the electronic display device, it is also possible to peel off the entire polymer film from the inorganic substrate at the stage where the process has progressed to step E, and re-adhere it to a newly prepared substrate of a prescribed size before proceeding to step F. From the viewpoint of suitability for the manufacturing process, it is preferable to use a highly heat-resistant inorganic substrate for the manufacture of electronic display devices, but when a lightweight and flexible product is required, one possible embodiment is to use a lighter and thinner substrate such as a polymer plate, polymer sheet or FRP plate. FIG. 2(B) shows a case where an adhesive is used instead of a silane coupling agent when bonding the polymer film and the substrate to obtain a laminate in steps B and C. FIG. 3(B) shows a case where a polymer film is bonded to the second surface of the inorganic substrate using an adhesive instead of a silane coupling agent in steps I to H. FIG. 6 shows a case where the display area is larger than the substrate size. FIG. 7 shows a case where there is a gap between the folded polymer film and the side surface of the substrate, and the gap is filled with casting resin 90.

[0051] Next, a process for producing the electronic display device of the present invention using the varnish method will be described with reference to FIG. 10, FIG. 11(A) and FIG. 11(B). Step A in FIG. 10 shows the substrate before processing. Step B in Fig. 10 shows a state in which a polymer solution or polymer precursor solution 35 is applied to the surface of the substrate. The silane coupling agent (layer) is omitted from the figure because it may or may not be used. However, when performing the patterning of adhesive strength described in Japanese Patent No. 5862866, a silane coupling agent is applied to the substrate, and a polymer solution or polymer precursor solution is applied after performing a preliminary treatment for patterning. Step C in FIG. 10 shows a state in which a polymer film is formed on the substrate after drying and, if necessary, chemical reaction. As with the film lamination method, steps A to C correspond to the "(a) step of preparing a laminate having a substrate and a polymer film adhered to at least one side of the substrate" in the varnish method. The subsequent steps are generally the same as those in the film lamination method. In step D of Fig. 10, wiring is formed on the surface of the polymer film opposite to the adhesive surface (non-adhesive side). For convenience, only the peripheral portion is shown. In step E of Figure 10, the electronic display device is formed. The wiring is actually connected to a wiring layer arranged in a mesh pattern within the electronic display device. Steps D and E correspond to “(b) the step of forming an electronic display device and wiring on a polymer film” in the varnish method. In step F of FIG. 10, a part of the substrate is removed to divide it into a display region X1 and a wiring region X2.

[0052] First, the latter half of the manufacturing process for an electronic display device using the varnish method will be described with reference to Fig. 11(A). Step G1 in Fig. 11(A) shows a state in which a slit 31 is made in the polymer film surrounding the periphery of the electronic display device from the side opposite to the side with wiring. 11A shows a state where a thinning process is carried out on the opposite side of the wiring of the polymer film surrounding the periphery of the electronic display device. In this case, the wiring also becomes a so-called flying lead 41. If the polymer film has thermoplastic properties, it is also possible to heat a portion of the polymer film, preferably locally, to a temperature above its heat distortion temperature and bend it, as in the case of using the film lamination method, and the polymer film can be bent without applying stress to the wiring portion even without the need for the slits or thinning. Step H in Figure 11(A) shows a case where the film is bent on the side without performing the slitting process in step G1 and the thinning process in step G2. A silane coupling agent 21 is applied in advance to the second surface (rear surface) of the substrate where the folded polymer film comes into contact. In this case, a dispenser or the like can be used to apply the required amount to the required locations. In a laboratory setting, it is also possible to apply the agent using a dropper or paintbrush. Step I in Fig. 11(A) shows a state in which the polymer film is folded and the corresponding portion of the polymer film is bonded to the second surface (rear surface) of the substrate via a silane coupling agent layer. In this case, as in steps A to C, the reaction of the silane coupling agent bonding the substrate and the polymer film and the self-condensation reaction proceed simultaneously in parallel to form a silane coupling agent layer. J in FIG. 11(A) shows the state in which a drive circuit element (driver IC) for an electronic display device is mounted. In this manner, an electronic display device having the configuration illustrated in FIG. 1(A) can be obtained (without the silane coupling agent layer between the first surface of the substrate and the polymer film layer). In the varnish method, as in the film lamination method, one possible embodiment is to peel off the entire polymer film from the inorganic substrate at the stage of step E, prepare a new substrate of a predetermined size, re-adhere the film, and proceed to step F.

[0053] In FIG. 11(B), the steps after step G are the same as those in the film lamination method. In the varnish method, as in the film lamination method, one possible embodiment is to peel off the entire polymer film from the inorganic substrate at the stage of step E, prepare a new substrate of a predetermined size, re-adhere the film, and proceed to step F.

[0054] In the present invention, it is preferable that the outer dimension Lo of the electronic display device and the outer dimension Ld of the display unit of the electronic display device have the following relationship. Lo<(1 / 2)×(Ld+5×Lpx) Here, Lo: External dimensions of electronic display device Ld: External dimensions of the display part of the electronic display device Lpx: the pixel size of an electronic display device. This relationship will be explained using Figures 13(A) and 13(B). Figures 13(A) and 13(B) show cross sections near the side surfaces of an electronic display device. The cutting direction of the cross section is either the X direction or the Y direction of the electronic display device. In the present invention, it is necessary for the above relationship to be established in either the X direction or the Y direction of the display device, or preferably in both directions. The dimension Lov of the area (overhang) outside the display area where images cannot be displayed is half the dimension obtained by subtracting the dimension Ld of the area where images can actually be displayed from the outer dimension Lo of the electronic display device. Lov can be understood as the minimum width of the frame. In the present invention, it is a preferable feature that the overhang width is 2.5 times or less than the pixel dimension. If the frame width is set to about 2.5 times the display pixel or less, the width of the non-display area that occurs when tiling is performed will be about 5 times the pixel size or less, and the tiling seam can be made inconspicuous. It is more preferably 2.4 times or less, even more preferably 2.2 times or less, and particularly preferably 2.0 times or less.

[0055] On the other hand, Lov in Figure 13(A) is the sum of the wiring thickness Lb and the side gap Lg. Here, the wiring thickness is the sum of the polymer film thickness and the wiring thickness. When the polymer film is thinned, it is the sum of the thinned polymer film thickness and the wiring thickness, and when the polymer film is completely removed at the bent portion, Lb is equal to the wiring thickness. Both the polymer film and the wiring have a finite bending elastic modulus. Therefore, (unless the polymer film is slit or thinned, or temporarily plasticized by heating) the polymer film is bent with a finite radius of curvature Ri. In this case, the radius of curvature corresponds to the sum of Lg and Lb, i.e., it is equal to Lov. Ri=Lg+Lb=Lov The above is a geometric solution for the ideal case where the polymer film and wiring are bent in a perfect arc. In reality, the bent part is distorted into an elliptical arc, so it deviates from the ideal shape. In the present invention, it is preferable to bend the wire so that the bending radius Rr is between 0.7 and 3 times Ri. 0.7×Lov≦Rr≦3×Lov It is preferably 0.8 times or more and 2.5 times or less, more preferably 1 time or more and 2 times or less.

[0056] When the polymer film and the wiring are bent with a radius of curvature Lov and the substrate thickness Ts is sufficiently thick (Ts>2×Lov), a section Lp can be provided where the substrate side is parallel to the polymer film and the wiring. Lp is calculated as Lp = Ts-2 × Lg This is also a geometric solution for an ideal deformation, and in reality it deviates from the ideal form, but in the present invention, it is preferable that Lp is at least 30% or more of the substrate thickness Ts. That is, Lp ≧ 0.3×Ts It is preferably 40% or more, more preferably 50% or more.

[0057] Also, Lov in Figure 13(B) is the sum of the flying wiring thickness Tw and the side gap Lg. The thickness of the flying wiring is equal to the wiring thickness. The flying wiring is bent with a finite radius of curvature Ri. In this case, the radius of curvature corresponds to the sum of Lg and Tw, i.e., it is equal to Lov. Ri=Lg+Tw=Lov The above is a geometric solution for the ideal case in which the polymer film and wiring layer are bent in a perfect arc. In reality, the bent part is distorted into an elliptical arc, so it deviates from the ideal shape. In the present invention, it is preferable to bend the wire so that the bending radius Rr is between 0.7 and 3 times Ri. 0.7×Lov≦Rr≦3×Lov It is preferably 0.8 times or more and 2.5 times or less, more preferably 1 time or more and 2 times or less.

[0058] When the flying wiring is bent with a curvature radius Lov and the substrate thickness Ts is sufficiently thick (Ts>2×Lov), a section Lp can be provided in which the substrate side is parallel to the wiring polymer film and the wiring layer. Lp is calculated as Lp = Ts-2 × Lg This is also a geometric solution for an ideal deformation, and in reality it deviates from the ideal form, but in the present invention, it is preferable that Lp is at least 30% or more of the substrate thickness Ts. That is, Lp ≧ 0.3×Ts It is preferably 40% or more, more preferably 50% or more.

[0059] 14 shows the state when resin is filled into the gaps that occur on the side of the electronic display device of the present invention. By filling the gaps with resin and fixing the shape of the polymer film on the side, the side shape of the electronic display device of the present invention can be maintained well. If a mold or the like is used during fixing, it is possible to make the side shape closer to the ideal shape. Figure 15 shows the state where there is substantially no gap in the side portion of the electronic display device of the present invention. It is possible to process the polymer film into such a shape by partially heating and plasticizing the polymer film. In this case, Lov is equal to the sum of the polymer film and wiring thickness, and the frame width can be made very narrow.

[0060] Figure 16 shows the case where there is no gap and the polymer film on the side of the substrate is further thinned. In this case, Lov becomes equal to the wiring thickness. FIG. 17 shows a configuration in which even more of the display area of ​​the electronic display device has been removed, and since the outer dimension Lo of the electronic display device and the dimension Ld of the display area of ​​the electronic display device are substantially equal, it is possible to eliminate the frame.

[0061] Figure 18 shows a conventional electronic display device using TAB, in which a silane coupling agent is used to bond the polymer film, which is the TAB base material, to the second surface of the substrate. The TAB and the electronic display device are connected by an anisotropic conductive film (ACF), but since the ACF portion cannot be used for display, the width of the ACF is included in the frame, which prevents the frame from being narrowed.

[0062] Fig. 19 is a detailed schematic cross-sectional view of the side of an electronic display device that has been proposed in the past and is similar to the present invention. The polymer film is bent with a large curvature, which results in a large overhang and makes it difficult to narrow the frame width. This type of shape occurs because the polymer film has poor flexibility and there is a high possibility that the film will be damaged if the curvature is reduced.

[0063] Fig. 20 is a detailed schematic cross-sectional view of the side of an electronic display device that has been proposed in the past and is similar to the present invention. The polymer film is bent with a large curvature, which results in a large overhang and makes it difficult to narrow the frame width. This type of shape occurs because the polymer film has poor flexibility, and reducing the curvature increases the possibility of the film being damaged.

[0064] Figure 12 shows a conventional electronic display device using TAB, in which a silane coupling agent is used to bond the polymer film, which is the TAB base material, to the second surface of the substrate. The TAB flying wiring and the electronic display device are connected by ACF (anisotropic conductive film). Since the ACF portion cannot be used for display, the width of the ACF is included in the frame, which hinders narrowing the frame. EXAMPLES

[0065] The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples. <Laminate Manufacturing A> (Film Lamination Method 1) (Manufacturing of polyimide film Apf) Colorless polyimide "Neoprene (registered trademark)" L-3430 manufactured by Mitsubishi Gas Chemical Company was pulverized and dissolved in NMP, and further, Snowtex (DMAC-ST30, manufactured by Nissan Chemical Industries, Ltd.) in which colloidal silica (average particle size: 0.08 μm) was dispersed in dimethylacetamide was added so that the colloidal silica accounted for 1.5 mass % of the total polymer solid content in polyimide solution A, thereby obtaining a polyimide solution Asol with a solid content of 18%. The obtained polyimide solution Asol was applied onto a mirror-finished endless continuous belt made of stainless steel (coating width: 1240 mm) using a die coater, and dried for 20 minutes at 90 to 115° C. After drying, the polyimide film became self-supporting, and was peeled off from the support and both ends were cut to obtain a green film Agf. The obtained green film Agf was conveyed by a pin tenter so that the final pin sheet interval was 1140 mm, and heat-treated at 150 ° C for 4 minutes in the first stage, 250 ° C for 4 minutes in the second stage, and 300 ° C for 8 minutes in the third stage, and then cooled to room temperature in 2 minutes, and the poorly flat parts at both ends of the film were cut off with a slitter, and rolled up into a roll to obtain a colorless and transparent polyimide film Apf. The obtained polyimide film had a thickness of 35 μm, a glass transition temperature of 303 ° C, a total light transmittance of 92%, a yellow index of 1.2, a tensile modulus of elasticity of 3.7 GPa, a tensile elongation at break of 24%, a coefficient of thermal expansion (CTE) of 58 ppm / K, a water absorption rate of 2.1%, and a coefficient of humidity expansion (CHE) of 63 ppm / % RH.

[0066] (Laminate manufacturing using film lamination method 1) One side of the polyimide film Apf was subjected to nitrogen plasma treatment using a vacuum plasma treatment device in a roll-to-roll system, and then cut into a square of 280 mm x 280 mm. An isopropyl alcohol solution containing 1% by mass of a silane coupling agent ("KBE-903" manufactured by Shin-Etsu Chemical Co., Ltd.) was coated onto a 300 mm x 300 mm, 0.5 mm thick glass substrate by spin coating, and then dried at 100°C for 1 minute. Furthermore, to weaken the activity of the silane coupling agent on the periphery of the glass (patterning treatment of adhesive strength), a central 250 mm x 250 mm portion of the glass was masked with a light-shielding plastic sheet, and the entire surface was irradiated with ultraviolet light using a UV / ozone cleaner manufactured by LAN Technical Services. Next, the plasma-treated surface of the film and the silane coupling agent-treated surface of the glass substrate were brought into contact with each other using a vacuum laminator, and heat-treated at 150° C. for 1 minute to obtain a laminate A.

[0067] <Laminate Manufacturing B> (Film Lamination Method 2) (Production of polyimide film Bpf) In a reaction vessel equipped with a nitrogen inlet tube, Dean-Stark apparatus, reflux tube, thermometer, and stirrer, 32.02 parts by mass of 2,2'-ditrifluoromethyl-4,4'-diaminobiphenyl (TFMB) and 230 parts by mass of N,N-dimethylacetamide (DMAc) were added and completely dissolved while introducing nitrogen gas, and then 44.42 parts by mass of 4,4'-(2,2-hexafluoroisopropylidene)diphthalic dianhydride (6FDA) was added in portions as a solid, and the mixture was stirred at room temperature for 24 hours. After that, a polyamic acid solution Bpaa with a solid content of 25% by mass and a reduced viscosity of 1.10 dl / g was obtained. Next, 204 parts by mass of DMAc was added to the obtained polyamic acid solution Bpaa to dilute the polyamic acid concentration to 15% by mass, and then 1.3 parts by mass of isoquinoline was added as an imidization promoter. Next, while stirring the polyamic acid solution, 12.25 parts by mass of acetic anhydride was slowly dropped as an imidization agent. After that, the mixture was stirred for 24 hours to carry out a chemical imidization reaction, and a polyimide solution Bsolz was obtained. Next, 100 parts by mass of the resulting polyimide solution Bsolz was transferred to a reaction vessel equipped with a stirring device and a stirrer, and 150 parts by mass of methanol was slowly added dropwise while stirring, whereupon precipitation of a powdery solid was confirmed. The powder content of the reaction vessel was then dehydrated and filtered, washed with methanol, and then vacuum dried at 50° C. for 24 hours, and then heated at 260° C. for an additional 5 hours to obtain polyimide powder Bpd. 20 parts by mass of the obtained polyimide powder Bpd was dissolved in 80 parts by mass of DMAc to obtain a polyimide solution Bsol.

[0068] In an atmosphere conditioned at 25°C and 45% RH, the polyimide solution Bsol was applied to the non-slip surface of a polyethylene terephthalate film A4100 (manufactured by Toyobo Co., Ltd., hereinafter abbreviated as PET film) serving as a temporary support, using an apparatus equipped with a roll-to-roll comma coater and a continuous drying oven, so that the final film thickness would be 25 μm. Next, the film was heated at 110°C for 10 minutes as primary heating using a continuous dryer, to obtain a semi-dried coating Bgf with a residual solvent content of 25% by mass, which was then wound up into a roll together with the temporary support. The obtained roll was set again in the above-mentioned device, Bgf was unwound together with the temporary support, Bgf was peeled off from the temporary support, passed through a pin tenter having a pin sheet, the film end was held by inserting it into the pin, the pin sheet interval was adjusted so that the film would not break and would not cause unnecessary slack, and the film was conveyed, and the final heating was performed under the conditions of 200° C. for 3 minutes, 250° C. for 3 minutes, and 300° C. for 6 minutes. After that, the film was cooled to room temperature in 2 minutes, and the parts with poor flatness at both ends of the film were cut off with a slitter, and the film was wound up into a roll to obtain a roll of polyimide film Bpf with a width of 530 mm and a length of 80 m. The obtained polyimide film had a thickness of 25 μm, a glass transition temperature of 320° C., a total light transmittance of 92%, a yellow index of 0.8, a tensile modulus of elasticity of 3.4 GPa, a tensile elongation at break of 18%, and a coefficient of thermal expansion (CTE) of 62 ppm / K.

[0069] (Laminate manufacturing using film lamination method 2) The polyimide film Bpf was cut to a size of 280 mm x 280 mm, and was subjected to UV irradiation for 3 minutes using a UV ozone layer value manufactured by LAN Technical Services as a surface activation treatment. A glass substrate of 300 mm x 300 mm and 0.5 mm thickness was exposed to a silane coupling agent ("KBE-903" manufactured by Shin-Etsu Chemical Co., Ltd.) at 40°C or higher for 5 minutes, and then held in dry nitrogen at 60°C for 5 minutes to be treated with the silane coupling agent. Next, the UV-irradiated surface of the film Bpf was joined to the silane coupling agent-treated surface of the glass substrate, and the two were bonded together using a vacuum laminator. Heat treatment was performed at 150°C for 1 minute to obtain a laminate B.

[0070] <Laminate manufacturing C> (Varnish method 1) The polyimide solution Asol obtained in the process of manufacturing the polyimide film Apf was applied to a glass substrate of 300 mm × 300 mm and 0.5 mm thickness using a bar coater so that the final film thickness would be 18 μm and the effective size would be 280 mm × 280 mm. The applied coating was then dried in a vacuum dryer at 250°C for 30 minutes and then heat-treated in a nitrogen-substituted inert furnace at 450°C for 5 minutes to obtain a laminate C consisting of a polyimide film layer and a glass substrate.

[0071] <Laminate manufacturing D> (Varnish method 2) The polyimide solution Bsol obtained during the production of the polyimide film Bpf was applied to a glass substrate of 300 mm × 300 mm and 0.5 mm thickness using a bar coater so that the final film thickness was 15 μm and the effective size was 280 mm × 280 mm. The applied film was then heat-treated in a vacuum dryer and a nitrogen-substituted inert furnace at 150°C for 10 minutes, 250°C for 10 minutes, and 300°C for 5 minutes to obtain a laminate D consisting of a polyimide film layer and a glass substrate.

[0072] <Manufacturing of simulated devices> Using the obtained laminates A to D, mock display devices were formed on the respective polyimide films. The layout (top view) of the mock display device is shown in FIG. 21. A polyimide film 300 is laminated on a glass substrate 150 by lamination or coating. The wiring 400 was formed by metallizing the polyimide film by sputtering nickel-chromium alloy and then sputtering copper to a thickness of 100 nm, then electroplating copper to a thickness of 8 μm, processing the wiring shape by an etching method, and further performing electroless tin plating on the wiring surface. The mock display device 600 was formed by masking the parts other than the predetermined range after the wiring was formed, and forming an amorphous silicon thin film to be regarded as a display device. The process up to this point corresponds to process E in FIG. 8 or process E in FIG. 10. Five mock display devices were fabricated using each of the laminates A to D, and the flying wiring was formed and molded into mock electronic display devices, as described below.

[0073] Example 1A First, a scribe was made in the glass substrate of the laminate A from the back side along the edge of the simulated display device that can be observed through the glass substrate, and then the glass substrate was divided to remove the glass portion that supported the wiring portion. This corresponds to step F in Fig. 8 or step F in Fig. 10. Next, a silane coupling agent was applied to the second surface of the substrate, which corresponds to step G in FIGS. 9(A) and (B) or step G in FIGS. 11(A) and (B). <Forming into a simulated display device> Next, a forming process corresponding to steps H to J in Figs. 9(A)(B) or 11(A)(B) was carried out. First, the area other than the wiring area near the display area corresponding to the bending part was masked with a light-shielding glass substrate from the second surface side, and then the corresponding part was heated by irradiating light from a xenon lamp using a light-curing machine "PulseForge" manufactured by Hitachi High-Tech Corporation. Immediately after, the wiring area of ​​the polymer film was first bent along the side of the glass substrate, and then bent along the back surface of the glass substrate. A polyimide film was attached to the back surface of the glass substrate (second surface) where a silane coupling agent had been applied in advance, and then the polyimide film was fixed with a clip together with a backing plate. The polyimide film was heated at 100°C for 5 minutes to bond the polyimide film to the back surface of the glass substrate. This part corresponds to the part where the driver IC is mounted. The temperature of the heated part was measured with an infrared radiation thermometer and was 370°C. <Examples 1B, 1C, and 1D> The same processing was carried out using laminates B to D. These are designated as Examples 1B, 1C, and 1D, respectively. In all cases, including Example 1A, no damage to the wiring was observed, and no particular problems occurred during the molding process.

[0074] Example 2A The same procedure was followed as in Example 1A, except that the bent portion was heated by contacting the corresponding portion with a stainless steel metal bar heated to 400°C. The temperature of the heated portion was measured with an infrared thermometer and found to be 380°C. <Examples 2B, 2C, and 2D> The same processing was carried out using laminates B to D. These are designated as Examples 2B, 2C, and 2D, respectively. In all cases, including Example 2A, no damage to the flying wiring was observed, and no particular problems were found during the molding processing.

[0075] (Preparation of polyamic acid solution (PAA1) and polyamic acid solution containing lubricant (V1)) The nitrogen inlet tube, thermometer, stirring rod, and infusion piping of the reaction vessel, which is made of austenitic stainless steel SUS316L, were replaced with nitrogen, and 223 parts by mass of 5-amino-2-(p-aminophenyl)benzoxazole (DAMBO) was added. Next, 4000 parts by mass of N-methyl-2-pyrrolidone was added and completely dissolved, and then 420 parts by mass and 217 parts by mass of pyromellitic dianhydride (PMDA) were added to the preliminary dispersion obtained above, and the mixture was stirred at 25°C for 48 hours to obtain a brown viscous polyamic acid solution (PAA1). The reduced viscosity (ηsp / C) was 5.5 dl / g. To the obtained polyamic acid solution (PAA1), a dispersion of colloidal silica dispersed in dimethylacetamide (Nissan Chemical Industries, Ltd.'s "Snowtex (registered trademark) DMAC-ST-ZL") was added as a lubricant so that the silica (lubricant) accounted for 0.5 mass% of the total polymer solid content in the polyamic acid solution, thereby obtaining a lubricated polyamic acid solution (V1).

[0076] The reduced viscosity of the polyamic acid was measured by the following method. <Reduced viscosity of polyamic acid (ηsp / C)> A solution of a polymer (polyamic acid) dissolved in N-methyl-2-pyrrolidone so as to give a polymer (polyamic acid) concentration of 0.2 g / dl was measured at 30° C. using an Ubbelohde type viscometer.

[0077] (Preparation of polyamic acid solution (PAA2) and polyamic acid solution containing lubricant (V2)) The nitrogen inlet tube, thermometer, stirring rod, and infusion piping of the reaction vessel made of austenitic stainless steel SUS316L were replaced with nitrogen, and 108 parts by mass of phenylenediamine (PDA) was added. Next, 3600 parts by mass of N-methyl-2-pyrrolidone was added and completely dissolved, and then 420 parts by mass and 292.5 parts by mass of diphenyltetracarboxylic dianhydride (BPDA) were added to the preliminary dispersion obtained above, and the mixture was stirred at 25°C for 12 hours to obtain a brown viscous polyamic acid solution (PAA2). The reduced viscosity (ηsp / C) was 4.5 dl / g. Colloidal silica was added in the same manner as in the preparation of polyamic acid solution (V1), and a lubricant-containing polyamic acid solution (V2) was obtained.

[0078] (Preparation of polyamic acid solution (PAA3) and polyamic acid solution containing lubricant (V3)) The liquid-contacting parts of the vessel equipped with a nitrogen inlet tube, a thermometer, and a stirring rod, and the infusion piping were made of austenitic stainless steel SUS316L, and the inside of the reaction vessel was replaced with nitrogen, and 200 parts by mass of diaminodiphenyl ether (ODA) was added. Next, 3800 parts by mass of N-methyl-2-pyrrolidone was added and completely dissolved, and then 390 parts by mass and 217 parts by mass of pyromellitic dianhydride (PMDA) were added to the preliminary dispersion obtained above, and the mixture was stirred at 25°C for 5 hours, resulting in a brown viscous polyamic acid solution (PAA3). The reduced viscosity (ηsp / C) was 3.7 dl / g. Colloidal silica was added in the same manner to obtain a polyamic acid solution containing a lubricant (V3).

[0079] [Preparation of polyamic acid solution (PAA4) and polyamic acid solution containing lubricant (V4)] After replacing the inside of a reaction vessel equipped with a nitrogen inlet tube, a thermometer, and a stirring rod with nitrogen, 1765 parts by mass of 1,2,3,4-cyclobutanetetracarboxylic dianhydride (CBDA), 310 parts by mass of 4,4'-oxydiphthalic acid (ODPA), 1601 parts by mass of 2,2'-ditrifluoromethyl-4,4'-diaminobiphenyl (TFMB), 1136 parts by mass of 4-amino-N-(4-aminophenyl)benzamide (DABAN), and 20000 parts by mass of N,N-dimethylacetamide were charged and dissolved in the reaction vessel under a nitrogen atmosphere, and then stirred at room temperature for 24 hours. After that, the mixture was diluted with an appropriate amount of N,N-dimethylacetamide to obtain a polyamic acid solution (PAA4) with a reduced viscosity of 4.50 dl / g. Colloidal silica was added in the same manner to obtain a polyamic acid solution (V4) containing a lubricant.

[0080] [Preparation of polyimide solution (PI5) and polyimide solution containing lubricant (V5)] After replacing the inside of a reaction vessel equipped with a nitrogen inlet tube, a thermometer, and a stirring rod with nitrogen, 4610 parts by mass of N,N-dimethylacetamide (DMAC) and 640 parts by mass of 2,2'-ditrifluoromethyl-4,4'-diaminobiphenyl (TFMB) were added to the reaction vessel under a nitrogen atmosphere and stirred to dissolve TFMB in DMAC. Next, while stirring the inside of the reaction vessel, 897.37 parts by mass of 4,4'-(2,2-hexafluoroisopropylidene)diphthalic dianhydride (6FDA) was added over about 10 minutes under a nitrogen stream, and the polymerization reaction was carried out by continuing stirring for 6 hours while adjusting the temperature to be in the range of 20 to 40 ° C., to obtain a viscous polyamic acid solution (PAA5). Next, 4100 parts by mass of DMAC was added to the obtained polyamic acid solution (PAA5) to dilute it, and then 258.3 parts by mass of isoquinoline was added as an imidization accelerator. The polyamic acid solution was kept at a temperature range of 30 to 40°C while stirring, and 1225 parts by mass of acetic anhydride was slowly added dropwise as an imidization agent over a period of about 10 minutes. The liquid temperature was then further kept at 30 to 40°C and stirring was continued for 12 hours to carry out a chemical imidization reaction, thereby obtaining a polyimide solution (PI5a).

[0081] Next, 10,000 parts by mass of the polyimide solution (PI5a) containing the obtained imidization agent and imidization accelerator was transferred to a reaction vessel equipped with a stirrer and agitator, and the temperature was kept at 15 to 25 ° C while stirring at a speed of 120 rpm, and 15,000 parts by mass of methanol was dropped therein at a rate of 10 g / min. When about 8,000 parts by mass of methanol was added, the polyimide solution became turbid and precipitation of powder-like polyimide resin was confirmed. Subsequently, the entire amount of 15,000 parts by mass of methanol was added, and precipitation of polyimide resin was completed. Next, the contents of the reaction vessel were filtered with a suction filtration device, and further washed and filtered with 10,000 parts by mass of methanol to obtain a polyimide resin powder. The obtained polyimide resin powder was dried at 50 ° C for 24 hours using a dryer equipped with a local exhaust device, and further dried at 260 ° C for 2 hours to remove the remaining volatile components, and a dry polyimide powder was obtained. The reduced viscosity of the obtained dry polyimide powder was 5.40 dl / g. Next, 400 parts by mass of the obtained dry polyimide powder was dissolved in 3000 parts by mass of DMAc to obtain a polyimide solution (PI5). Colloidal silica was then added in the same manner to obtain a polyimide solution containing a lubricant (V5). The resulting polyamic acid solutions or polyimide solutions, and solutions containing lubricants, are listed in Tables 1 and 2.

[0082] [Table 1]

[0083] [Table 2]

[0084] [Film manufacturing example] The lubricant-containing polyamic acid solution (V1) was pumped and coated onto a polyethylene terephthalate film support to a final thickness of 38 μm, and then dried for 30 minutes at 110° C. The polyamic acid film, which had become self-supporting after drying, was peeled off from the support to obtain a polyamic acid film (green film). The obtained green film was passed through a continuous heat treatment furnace and heated in two stages, with the first stage at 200°C for 3 minutes, the temperature increased at a rate of 4°C / sec, and the second stage at 480°C for 5 minutes, to allow the imidization reaction to proceed. It was then cooled to room temperature in 5 minutes, and both ends (edges) were slit to obtain a polyimide film F1 with a width of 524 mm, a length of approximately 200 m, and a thickness of 38 μm at the center only.

[0085] Similarly, polyimide film F2 was obtained from polyamic acid solution V2, polyimide film F3 from polyamic acid solution V3, polyimide film F4 from polyamic acid solution V4, and polyimide film F5 from polyamic acid solution V5 by appropriately adjusting the coating thickness and heat treatment conditions. The properties of the obtained polyimide films are shown in Table 3. The values ​​in the table are the average values ​​in the MD and TD directions. MD is the longitudinal direction when the film is formed, and TD is the transverse direction when the film is formed.

[0086] [Table 3]

[0087] [Polyimide film / glass substrate laminate] <Vacuum plasma treatment of polyimide film> The polyimide film F1 was subjected to vacuum plasma treatment. The vacuum plasma treatment was performed using a device for treating long films, and the inside of the vacuum chamber was heated to 1×10 -3 The vacuum chamber was evacuated to a pressure of less than 1 Pa, and argon gas was introduced into the vacuum chamber, followed by argon gas plasma treatment for 20 seconds under conditions of a discharge power of 100 W and a frequency of 15 kHz.

[0088] <Silane coupling agent treatment of glass substrate> Glass substrate [G] was OM10G manufactured by Nippon Electric Glass Co., Ltd., measuring 470 mm x 370 mm and 0.7 mm thick. After replacing the atmosphere in a chamber equipped with a hot plate and a support stand for inorganic substrates with clean dry nitrogen, the glass substrate that had been subjected to UV / ozone treatment was placed on the support stand, and a petri dish filled with a silane coupling agent (3-aminopropyltrimethoxysilane) was placed so that the liquid level was located 200 mm below the glass substrate. The petri dish was heated to 100°C on a hot plate, and the bottom surface of the glass substrate was exposed to the silane coupling agent vapor for 3 minutes. After that, the petri dish was removed from the chamber and placed in a clean bench. The glass substrate was placed on a hot plate adjusted to 120°C so that the opposite side of the exposed surface of the glass substrate was in contact with the hot plate, and heat treatment was performed for 1 minute to perform silane coupling agent treatment.

[0089] <Lamination> The plasma-treated surface of the polyimide film was placed on the silane coupling agent-treated surface of the glass substrate, and the polyimide film was temporarily pressed with a roll laminator. The polyimide film was then placed in a clean bench and placed on a hot plate adjusted to 150°C with the inorganic substrate side in contact with the hot plate, and heat-treated for 3 minutes to obtain a polyimide film / glass substrate laminate (LF1). The polyimide / glass substrate laminate was stored in an environment with a temperature of 20 to 25°C and a relative humidity of 65±30%. Similarly, a polyimide film / glass substrate laminate (LF2) was obtained from film F2 and a glass substrate. Further, polyimide film / glass substrate laminates (LF3), (LF4), and (LF5) were obtained from films F3, F4, and F5 and a glass substrate in the same manner.

[0090] <Example 3> Using the obtained polyimide film / glass substrate laminate, a display panel was fabricated in a simulated manner by the process shown in Fig. 8 and Fig. 9A. For convenience, this process is called the film method. The glass substrate corresponds to step A in Fig. 8, the glass substrate treated with a silane coupling agent corresponds to step B, and the polyimide film / glass laminate corresponds to step C. For the wiring layer 40, a nickel-chromium alloy layer was formed by a sputtering method, and then a copper thin film was formed by a sputtering method, which was then thickened by electrolytic copper plating, and unnecessary parts were etched away using an etching resist, thereby forming the wiring 40 by patterning using a so-called subtractive method.

[0091] As the electronic display device layer 60, an electrophoretic element driven by a TFT using an amorphous silicon thin film as a semiconductor was formed, the glass substrate was cut with a laser cutter to remove unnecessary parts, the film was thinned to 20% of the original thickness using a laser processing machine in step G2 of Fig. 9A, and the wiring 40 was folded to the back side of the glass substrate together with the film. As the silane coupling agent solution 21, a 1% by mass solution of 3-aminopropyltrimethoxysilane in methanol was used, and dropped at a predetermined position with a dispenser (for convenience, the display device layer is illustrated as the upper surface, but in reality, the operation is performed upside down after this step), and the polyimide film folded after drying was pressed against the back side of the glass substrate in accordance with the preparation of a polyimide film / glass substrate laminate, and then heated to complete the adhesion, and finally a driver IC was mounted to obtain a simulated panel (PF1). In the same way, multiple (PF1) panels were created, arranged in a tiled pattern to make a larger surface area, and image signals were sent to check the display. There were no particular pixel defects between the simulated panels, and it was confirmed that good quality images were displayed.

[0092] <Examples 4 to 7> Thereafter, the polyimide film glass laminates (LF2), (LF3), (LF4), and (LF5) were used to obtain simulated panels (PF2), (PF3), (PF4), and (PF5) in the same manner. All of them achieved good image display results over a large area by tiling.

[0093] <Example 8> Next, an example using the varnish method is shown. Step A in Figure 10 is a glass substrate. Step B is when a polyamic acid solution (PAA1) is applied to a glass substrate to a specified thickness, and step C is when a polyimide layer is formed by drying and then heating in an inert oven, i.e., a polyimide layer / glass substrate laminate (LS1) is obtained. Thereafter, the same operations as in the film method were carried out, and the process proceeded to the steps shown in Figure 11A. In step G1, a laser processing machine was used to make a half-cut cut in the film to fold the wiring part together with the film, and the same operations were carried out thereafter to produce a simulated panel (PS1). This was also tiled in the same way as in the film method, and the display image quality was observed, and it was confirmed that good image quality was obtained.

[0094] <Examples 9 to 11> Similarly, simulation panels (PS2), (PS3), and (PS4) were obtained from polyamic acid solutions (PAA2), (PAA3), and (PAA4). All of them showed good image display results by tiling. [Industrial Applicability]

[0095] As described above, the electronic display device of the present invention can have a narrow frame, has a low defect rate for driver IC mounting, and is preferably applicable to self-emissive elements and reflective elements, resulting in a display device suitable for tiling applications. The present invention will make a significant contribution to the industrial world, particularly as a technology for economically manufacturing large-area display devices. [Explanation of symbols]

[0096] 1:Electronic display 10: Substrate 15: Circuit board 20: Silane coupling agent condensation product layer 21: Silane coupling agent (solution) 30: Polymer film 31: Slit section (half cut section) 32: Polyimide etching section 33: Heating area 35: Polymer solution or polymer precursor solution 40: Wiring 41: Thinned part 42: Flying lead section 50: Driver circuit elements for electronic display devices (driver ICs) 60: Electronic display devices 70: Adhesive layer 80: Anisotropic conductive film (ACF) 90: Casting resin 150: Glass substrate 300: Polyimide film 310: Cutout area of ​​polyimide film 400: Wiring 600: Simulated display device X1: Area 1 (display area) X2: Area 2 (wiring area) Lo: External dimensions of electronic display device Ld: External dimensions of the display part of the electronic display device Lg: Side gap Lb: Wiring thickness (polymer film thickness Tf + wiring thickness Tw) Lp: Parallel side dimension Lpx: the pixel size of an electronic display device Lov: Overhang dimension (Lg+Lb) Ts: substrate thickness Tf: Polymer film thickness Tw: Wiring thickness (flying wiring layer thickness)

Claims

1. substrate, a polymer film having a heat resistance of 100° C. or more, which is folded so as to sandwich the substrate and is bonded to both the first surface and the second surface of the substrate; a wiring formed on a surface of the polymer film opposite to the surface bonded to the substrate, the wiring extending from a first surface side to a second surface side of the substrate; an electronic display device formed on the surface of the polymer film opposite to the surface bonded to the substrate; 13. An electronic display device comprising:

2. 2. The electronic display device according to claim 1, wherein the polymer film is a film made of any one of polyester, polyamide, polyamideimide, polyimide, polybenzazole, polyimidebenzazole, polyethylene naphthalate, liquid crystal polymer, polybenzoxazole, and polyimidebenzoxazole.

3. 3. The electronic display device according to claim 1, wherein the polymer film has an elastic modulus of 3 GPa or more and a breaking elongation of 3% or more.

4. 4. The electronic display device according to claim 1, wherein the polymer film is a polyimide film having a thickness of 3 μm or more and 75 μm or less.

5. 5. The electronic display device according to claim 1, wherein the polymer film is a polyimide film having a total light transmittance of 85% or more and a yellow index of 5 or less.

6. 6. The electronic display device according to claim 1, wherein the polymer film and the first surface of the substrate are bonded via a silane coupling agent condensate layer.

7. 7. The electronic display device according to claim 1, wherein the polymer film and the second surface of the substrate are bonded via a silane coupling agent condensate layer.

8. 8. The electronic display device according to claim 1, wherein the polymer film and the side surface of the substrate are bonded via a silane coupling agent condensate layer.

9. 9. The electronic display device according to claim 1, wherein a part or all of the portion of the polymer film facing the side surface of the substrate is thinned.

10. 10. The electronic display device according to claim 1, wherein a portion of the polymer film facing the side surface of the substrate is removed.

11. 11. The electronic display device according to claim 1, wherein a driving IC for the electronic display device is mounted on the second surface side of the substrate.

12. (a) providing a laminate having a substrate and a polymeric film adhered to at least one side of the substrate; (b) forming an electronic display device and wiring on the polymer film; (c) removing the substrate outside the region where the electronic display device is formed, and dividing the substrate into a display region bonded to the substrate and a wiring region from which the substrate has been removed; (d) heating the vicinity of the boundary between the display area and the wiring area to a temperature equal to or higher than the softening point of the polymer film, and bending the wiring area along a side surface of the substrate; 12. The method for manufacturing an electronic display device according to claim 1, further comprising at least the step (e) of bending the wiring region from a side surface of the substrate towards a rear surface (second surface).

13. 13. The method for manufacturing an electronic display device according to claim 12, wherein the heating means is light irradiation.

14. 13. The method of claim 12, wherein the heating means is direct contact with a heated object.

15. 13. The method for manufacturing an electronic display device according to claim 12, wherein the heating means is electromagnetic induction heating.

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