Laminated body, method for manufacturing laminated body, and method for manufacturing flexible electronic device

Abstract

Provided is a laminate that is useful as a temporary support for producing a large-area, high-definition, flexible electronic device, the laminate having stably low adhesive strength between a heat-resistant polymer film and an inorganic substrate even in the case of a large surface area, and having few blister defects.　This laminate has an inorganic substrate, a silane coupling agent layer that includes amino groups, and a heat-resistant polymer film in the stated order, the laminate being characterized in that the elemental nitrogen component ratio in an inorganic-substrate-side peel surface after the heat-resistant polymer film has been peeled from the inorganic substrate at 90° is greater than 3.5 at% and no greater than 11 at%.

Description

Technical Field

[0001] The present invention relates to a laminate, a method for manufacturing the laminate, and a method for manufacturing a flexible electronic device.

Background Art

[0002] In recent years, for the purpose of reducing the weight, miniaturizing and thinning, and making flexible functional elements such as semiconductor elements, MEMS elements, and display elements, active research and development has been carried out on technologies for forming these elements on polymer films. That is, as a material for the base of electronic components such as information and communication devices (broadcast devices, mobile wireless, mobile communication devices, etc.), radars, and high-speed information processing devices, conventionally, ceramics having heat resistance and capable of coping with the high frequency of the signal band of information and communication devices (reaching the GHz band) have been used. However, since ceramics are not flexible and difficult to thin, there is a drawback that the applicable fields are limited. Therefore, recently, polymer films have been used as substrates.

[0003] When forming functional elements such as semiconductor elements, MEMS elements, and display elements on the surface of a polymer film, it is ideal to process them by a so-called roll-to-roll process that utilizes the flexibility of the polymer film. However, in industries such as the semiconductor industry, MEMS industry, and display industry, process technologies have been constructed so far for rigid planar substrates based on wafers or glass substrates. Therefore, in order to form functional elements on a polymer film using existing infrastructure, a process is used in which the polymer film is bonded to a rigid support (inorganic substrate) made of an inorganic material such as a glass plate, ceramic plate, silicon wafer, or metal plate, a desired element is formed thereon, and then peeled off from the support.

[0004] By the way, in the process of forming a desired functional element on a laminate obtained by laminating a polymer film and a support made of an inorganic material, the laminate is often exposed to high temperatures. For example, in the formation of functional elements such as polysilicon and oxide semiconductors, processes in a temperature range of about 200°C to 600°C are required. In addition, in the production of a hydrogenated amorphous silicon thin film, a temperature of about 200 to 300°C may be applied to the film, and further heating of about 450°C to 600°C may be required to heat and dehydrogenate amorphous silicon to form low-temperature polysilicon. Therefore, the polymer film constituting the laminate is required to have heat resistance. However, in reality, there are limited polymer films that can withstand practical use in such a high-temperature range. In addition, it is generally considered to use an adhesive or an adhesive for laminating the polymer film to the support. In this case, heat resistance is also required for the joint surface between the polymer film and the support (that is, the adhesive or adhesive for laminating). However, ordinary adhesives and adhesives for laminating do not have sufficient heat resistance. Therefore, when the formation temperature of the functional element is high, lamination using an adhesive or an adhesive cannot be applied.

[0005] Since there is no adhesive or adhesive having sufficient heat resistance, conventionally, in the above-described applications, a technique has been adopted in which a polymer solution or a precursor solution of a polymer is applied onto an inorganic substrate, dried and cured on the inorganic substrate to form a film, and used for such applications. However, the polymer film obtained by such means is brittle and easily torn. Therefore, the functional element formed on the surface of the polymer film is often broken when peeled off from the inorganic substrate. In particular, it is extremely difficult to peel off a large-area film from the inorganic substrate, and it is almost impossible to obtain an industrial yield. In view of such circumstances, a laminate in which a polyimide film having excellent heat resistance, toughness, and capable of being thinned is laminated to an inorganic substrate via a silane coupling agent has been proposed as a laminate of a polymer film and an inorganic substrate for manufacturing a so-called flexible electronic device in which a functional element is formed on a flexible substrate (see, for example, Patent Documents 1 to 3).

Prior Art Documents

Patent Document

[0006]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0007] In the above-described laminate, by interposing a layer containing a silane coupling agent between the inorganic substrate and the heat-resistant polymer film, it is possible to prevent the inorganic substrate from peeling off from the polyimide film before or during device formation, and after device formation, it is intended to easily peel off the inorganic substrate from the polyimide film. However, since the adhesive strength between the polymer film and the inorganic substrate varies depending on the thickness of the silane coupling agent, it is extremely difficult to control the adhesive strength between the two with uniform adhesive strength over a large area. That is, it is difficult to apply the silane coupling agent to a large-sized substrate with a uniform thickness. In particular, in the case of a glass substrate having a size of 730 mm × 920 mm or more, which is called the 4.5th generation, the difficulty is much higher compared to the 4th generation (660 mm × 800 mm) size, and there were many problems in industrial production.

Means for Solving the Problems

[0008] In view of such circumstances, the inventors of the present invention have conducted intensive research. As a result, even in a large area exceeding the size of the 4.5th generation, it is possible to easily control the thickness of the silane coupling agent to be extremely thin and uniform, and a manufacturing method capable of obtaining a laminate with few blister defects and high quality has been found. Further, by the manufacturing method of the present invention, a laminate in which a heat-resistant polymer film and an inorganic substrate are laminated with an extremely uniform and extremely thin silane coupling agent layer is realized. Furthermore, it has been found that by using such a laminate, a high-quality flexible electronic device can be manufactured. That is, the present invention has the following configurations. [1] A laminate having an inorganic substrate, a silane coupling agent layer containing an amino group, and a heat-resistant polymer film in this order, wherein the nitrogen element component ratio of the peeling surface on the inorganic substrate side after peeling the heat-resistant polymer film from the inorganic substrate at 90° exceeds 3.5 atomic% and is 11 atomic% or less. [2] The laminate according to [1], wherein the adhesive strength by the 90° peeling method when peeling the heat-resistant polymer film from the laminate is 0.06 N / cm or more and 0.25 N / cm or less. [3] The laminate according to [1] or [2], wherein the surface roughness Ra of the inorganic substrate is 1 nm or more and 1000 nm or less. [4] The laminate according to any one of [1] to [3], wherein the heat-resistant polymer film is a polyimide film. [5] The laminate according to any one of [1] to [4], wherein the blister defect density is 5 or less per square meter. [6] The laminate according to any one of [1] to [5], wherein the heat-resistant polymer film is rectangular, the area is 0.65 square meters or more, and one side of the rectangle is at least 700 mm or more. [7] (1) A step of applying a silane coupling agent containing an amino group to at least one surface of an inorganic substrate. (2) A step of supplying an aqueous medium to the silane coupling agent-coated surface of the inorganic substrate and / or the adhesive surface side of the heat-resistant polymer film. (3) Step of overlapping the silane coupling agent-coated surface of the inorganic substrate and the heat-resistant polymer film. (4) Step of pressing both while extruding the aqueous medium from between the silane coupling agent-coated surface of the inorganic substrate and the bonding surface of the heat-resistant polymer film. A method for manufacturing a laminate having, in this order, an inorganic substrate, a silane coupling agent layer containing an amino group, and a heat-resistant polymer film, characterized by comprising at least the above. [8] (1) Step of applying a silane coupling agent containing an amino group to at least one surface of a heat-resistant polymer film. (2) Step of supplying an aqueous medium to the bonding surface side of the inorganic substrate and / or the silane coupling agent-coated surface of the heat-resistant polymer film. (3) Step of overlapping the inorganic substrate and the silane coupling agent-coated surface of the heat-resistant polymer film. (4) Step of pressing both while extruding the aqueous medium from between the bonding surface of the inorganic substrate and the silane coupling agent-coated surface of the heat-resistant polymer film. A method for manufacturing a laminate having, in this order, an inorganic substrate, a silane coupling agent layer containing an amino group, and a heat-resistant polymer film, characterized by comprising at least the above. [9] A method for manufacturing a flexible electronic device, comprising a step of forming a functional element on the surface of the heat-resistant polymer film of the laminate obtained in the manufacturing process according to [7] or [8], which is opposite to the bonding surface with the inorganic substrate. [Advantages of the Invention]

[0009] As described in the prior art, in a laminate of a heat-resistant polymer film for manufacturing a flexible electronic device and an inorganic substrate such as a glass plate, it is difficult to uniformly apply a silane coupling agent, especially in a large area. As a result, it has been difficult to uniformly and appropriately control the adhesion strength between the heat-resistant polymer film and the inorganic substrate. However, according to the present invention, this adhesive strength can be controlled within the range of 0.06 N / cm or more and 0.25 N / cm or less. Further, blister defects between the heat-resistant polymer film and the inorganic substrate are less likely to occur, and a large-area laminate in the shape of a rectangle with an area of 0.65 square meters or more and at least one side of 700 mm or more can be realized. Furthermore, by using this laminate, a method for manufacturing a large-area flexible electronic device can be provided.

[0010] Hereinafter, in order to avoid complexity, the heat-resistant polymer film may sometimes be simply referred to as a polymer film or a film, and the inorganic substrate may sometimes be simply referred to as a substrate. Also, the silane coupling agent is simply an amino group-containing silane coupling agent. The present invention is the same as the prior art in that after applying a silane coupling agent to either the polymer film or the inorganic substrate, the two are bonded (laminated). However, in the lamination process, a significant difference is that an aqueous medium (for example, pure water or a mixed solvent of water and a water-soluble solvent such as a lower alcohol) is interposed between the two, and the lamination is performed while extruding the aqueous medium out from the bonding surface. By such a method, an excess silane coupling agent between the inorganic substrate and the polymer film can be removed, and the amount of the silane coupling agent is controlled to the minimum necessary amount that is disposed on at least one of the surfaces of the substrate and the film with affinity. It is presumed that the adhesive force between the substrate and the polymer film changes over time or after a high-temperature process because the reaction of the excessively present and unreacted silane coupling agent proceeds. However, according to the method of the present invention, such excess unreacted substances can be excluded from the bonding interface between the substrate and the film.

[0011] By this method, a laminate can be obtained in which the nitrogen element (N element) component ratio observed by ESCA on the surface of the inorganic substrate after peeling the film is more than 3.5 atomic% and 11 atomic% or less. This N element reflects the presence of the amino group-containing silane coupling agent. Therefore, even in the case of a substrate that does not contain Si atoms in the substrate, such as a SUS substrate, a Cu substrate, or an Al2O3 substrate, the Si element component ratio of the peeling surface on the inorganic substrate side after peeling the heat-resistant polymer film from the inorganic substrate at 90° is detected to be about 15 atomic% to 25 atomic%.

[0012] Furthermore, in this bonding method, in order to eliminate excess silane coupling agent, it becomes difficult to generate foreign matter due to the condensation of the silane coupling agent. At the same time, dust and the like mixed on the bonding surface are also extruded, so that the foreign matter with a particle diameter at the bonding interface is drastically reduced, and as a result, the number of blister defects (also called bubbles, floating, etc.) caused by these foreign matters as nuclei is reduced.

[0013] According to the above configuration, the silane coupling agent layer has a thickness with sufficient adhesive strength and there is no excess silane coupling agent, so the adhesive strength is not too strong, and the initial adhesive strength is in the range of 0.06 N / cm or more and 0.25 N / cm or less. This is also clear from the examples. In this regard, the inventors of the present invention believe that in the initial stage of depositing the silane coupling agent on the inorganic substrate, since there are many OH groups on the surface of the inorganic substrate, as a result of the OH groups and the silane coupling agent layer being bonded by hydrogen bonds or chemical reactions, etc., a strong silane coupling agent layer can be obtained. However, when the deposition time of the silane coupling agent is prolonged, a silane coupling agent layer that is not necessarily strongly bonded easily enters the heat-resistant polymer film, and it is presumed that the adhesive strength changes depending on the bonding method at the place where it enters.

[0014] In the above configuration, it is preferable that the 90° (90 degrees) initial adhesive strength between the heat-resistant polymer film and the inorganic substrate is 0.06 N / cm or more and 0.25 N / cm or less.

[0015] When the initial adhesion strength at 90 degrees is 0.06 N / cm or more, it is possible to suitably prevent the heat-resistant polymer film from peeling off from the inorganic substrate before or during device formation. When the initial adhesion strength at 90 degrees is 0.25 N / cm or less, it can be peeled off without destroying the device during mechanical peeling.

[0016] In the above configuration, it is preferable that the blister defect density between the heat-resistant polymer film and the inorganic substrate is 5 or less per square meter.

[0017] The surface roughness Ra of the inorganic substrate is preferably 1 nm or more and 1000 nm or less.

[0018] In the above configuration, it is preferable that the number of bubbles between the heat-resistant polymer film and the inorganic substrate is 1 or less per 500 mm × 500 mm.

[0019] When the number of bubbles is 1 or less per 500 mm × 500 mm, the possibility of the device being destroyed due to the growth of bubbles can be significantly reduced when manufacturing the device on the heat-resistant polymer film.

Brief Description of the Drawings

[0020]

Figure 1

Embodiments for Carrying Out the Invention

[0021] In this specification, a heat-resistant polymer is a polymer having a melting point preferably of 400 °C or higher, more preferably 500 °C or higher, and a glass transition temperature preferably of 250 °C or higher, more preferably 320 °C or higher, and even more preferably 380 °C or higher. Hereinafter, it is also simply referred to as a polymer to avoid complexity. In this specification, the melting point and the glass transition temperature are determined by differential scanning calorimetry (DSC). When the melting point exceeds 500 °C, it may be determined whether the melting point has been reached by observing the thermal deformation behavior when heated at the corresponding temperature.

[0022] Examples of the heat-resistant polymer film (hereinafter also simply referred to as the polymer film) include polyimide-based resins such as polyimide, polyamideimide, polyetherimide, and fluorinated polyimide (for example, aromatic polyimide resin, alicyclic polyimide resin); copolyester such as polyethylene, polypropylene, polyethylene terephthalate, polybutylene terephthalate, and polyethylene-2,6-naphthalate (for example, wholly aromatic polyester, semi-aromatic polyester); copolymerized (meth)acrylate typified by polymethyl methacrylate; polycarbonate; polyamide; polysulfone; polyethersulfone; polyetherketone; cellulose acetate; cellulose nitrate; aromatic polyamide; polyvinyl chloride; polyphenol; polyarylate; polyphenylene sulfide; polyphenylene oxide; and films such as polystyrene. However, since it is a prerequisite that the polymer film be used in a process involving heat treatment at 450°C or higher, the materials that can actually be applied from the exemplified polymer films are limited. Among the polymer films, preferably, a film using so-called super engineering plastics is used. More specifically, examples include aromatic polyimide film, aromatic amide film, aromatic amideimide film, aromatic benzoxazole film, aromatic benzothiazole film, and aromatic benzimidazole film.

[0023] Details of a polyimide-based resin film (sometimes referred to as a polyimide film), which is an example of the polymer film, will be described below. Generally, a polyimide-based resin film is obtained by applying a polyamic acid (polyimide precursor) solution, which is obtained by reacting diamines and tetracarboxylic acids in a solvent, to a support for producing a polyimide film, drying it to form a green film (hereinafter also referred to as a "polyamic acid film"), and then performing a high-temperature heat treatment on the green film on the support for producing a polyimide film or in a state where it is peeled off from the support to cause a dehydration ring-closing reaction.

[0024] The application of the polyamic acid (polyimide precursor) solution can be appropriately carried out using conventionally known solution application means such as spin coating, doctor blade, applicator, comma coater, screen printing method, slit coating, reverse coating, dip coating, curtain coating, slit die coating, etc.

[0025] There are no particular restrictions on the diamines that make up the polyamic acid, and aromatic diamines, aliphatic diamines, alicyclic diamines, etc., which are usually used in polyimide synthesis, can be used. From the viewpoint of heat resistance, aromatic diamines are preferred, and among the aromatic diamines, aromatic diamines having a benzoxazole structure are more preferred. When aromatic diamines having a benzoxazole structure are used, it becomes possible to exhibit high heat resistance, a high elastic modulus, low thermal shrinkage, and a low linear expansion coefficient. The diamines may be used alone or in combination of two or more.

[0026] The aromatic diamines having a benzoxazole structure are not particularly limited. For example, 5-amino-2-(p-aminophenyl)benzoxazole, 6-amino-2-(p-aminophenyl)benzoxazole, 5-amino-2-(m-aminophenyl)benzoxazole, 6-amino-2-(m-aminophenyl)benzoxazole, 2,2'-p-phenylenebis(5-aminobenzoxazole), 2,2'-p-phenylenebis(6-aminobenzoxazole), 1-(5-aminobenzoxazolyl)-4-(6-aminobenzoxazolyl)benzene, 2,6-(4,4'-diaminodiphenyl)benzo[1,2-d:5,4-d']bisoxazole, 2,6-(4,4'-diaminodiphenyl)benzo[1,2-d:4,5-d']bisoxazole, 2,6-(3,4'-diaminodiphenyl)benzo[1,2-d:5,4-d']bisoxazole, 2,6-(3,4'-diaminodiphenyl)benzo[1,2-d:4,5-d']bisoxazole, 2,6-(3,3'-diaminodiphenyl)benzo[1,2-d:5,4-d']bisoxazole, 2,6-(3,3'-diaminodiphenyl)benzo[1,2-d:4,5-d']bisoxazole, etc. can be mentioned.

[0027] Examples of aromatic diamines other than the aromatic diamines having the benzoxazole structure described above include 2,2'-dimethyl-4,4'-diaminobiphenyl, 1,4-bis[2-(4-aminophenyl)-2-propyl]benzene (bisaniline), 1,4-bis(4-amino-2-trifluoromethylphenoxy)benzene, 2,2'-ditrifluoromethyl-4,4'-diaminobiphenyl, 4,4'-bis(4-aminophenoxy)biphenyl, 4,4'-bis(3-aminophenoxy)biphenyl, bis[4-(3-aminophenoxy)phenyl]ketone, bis[4-(3-aminophenoxy)phenyl]sulfide, bis[4-(3-aminophenoxy)phenyl]sulfone, 2,2-bis[4-(3-aminophenoxy)phenyl]propane, 2,2-bis[4-(3-aminophenoxy)phenyl]-1,1,1,3,3,3-hexafluoropropane, m-phenylenediamine, o-phenylenediamine, p-phenylenediamine, m-aminobenzylamine, p-aminobenzylamine, 3,3'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl ether, 3,3'-diaminodiphenyl sulfide, 3,3'-diaminodiphenyl sulfoxide, 3,4'-diaminodiphenyl sulfoxide, 4,4'-diaminodiphenyl sulfoxide, 3,3'-diaminodiphenyl sulfone, 3,4'-diaminodiphenyl sulfone, 4,4'-diaminodiphenyl sulfone, 3,3'-diaminobenzophenone, 3,4'-diaminobenzophenone, 4,4'-diaminobenzophenone, 3,3'-diaminodiphenylmethane, 3,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylmethane, bis[4-(4-aminophenoxy)phenyl]methane, 1,1-bis[4-(4-aminophenoxy)phenyl]ethane, 1,2-bis[4-(4-aminophenoxy)phenyl]ethane, 1,1-bis[4-(4-aminophenoxy)phenyl]propane, 1,2-bis[4-(4-aminophenoxy)phenyl]propane, 1,3-bis[4-(4-aminophenoxy)phenyl]propane, 2,2-bis[4-(4-aminophenoxy)phenyl]propane, 1,1-bis[4-(4-aminophenoxy)phenyl]butane, 1,3-bis[4-(4-aminophenoxy)phenyl]butane, 1,4-bis[4-(4-aminophenoxy)phenyl]butane, 2,2-bis[4-(4-aminophenoxy)phenyl]butane, 2,3-bis[4-(4-aminophenoxy)phenyl]butane, 2-[4-(4-aminophenoxy)phenyl]-2-[4-(4-aminophenoxy)-3-methylphenyl]propane, 2,2-bis[4-(4-aminophenoxy)-3-methylphenyl]propane, 2-[4-(4-aminophenoxy)phenyl]-2-[4-(4-aminophenoxy)-3,5-dimethylphenyl]propane, 2,2-bis[4-(4-aminophenoxy)-3,5-dimethylphenyl]propane, 2,2-bis[4-(4-aminophenoxy)phenyl]-1,1,1,3,3,3-hexafluoropropane, 1,4-bis(3-aminophenoxy)benzene, 1,3-bis(3-aminophenoxy)benzene, 1,4-bis(4-aminophenoxy)benzene, 4,4'-bis(4-aminophenoxy)biphenyl, bis[4-(4-aminophenoxy)phenyl]ketone, bis[4-(4-aminophenoxy)phenyl]sulfide, bis[4-(4-aminophenoxy)phenyl]sulfoxide, bis[4-(4-aminophenoxy)phenyl]sulfone, bis[4-(3-aminophenoxy)phenyl]ether, bis[4-(4-aminophenoxy)phenyl]ether, 1,3-bis[4-(4-aminophenoxy)benzoyl]benzene, 1,3-bis[4-(3-aminophenoxy)benzoyl]benzene, 1,4-bis[4-(3-aminophenoxy)benzoyl]benzene, 4,4'-bis[(3-aminophenoxy)benzoyl]benzene, 1,1-bis[4-(3-aminophenoxy)phenyl]propane, 1,3-bis[4-(3-aminophenoxy)phenyl]propane, 3,4'-diaminodiphenylsulfide, 2,2-bis[3-(3-aminophenoxy)phenyl]-1,1,1,3,3,3-hexafluoropropane, bis[4-(3-aminophenoxy)phenyl]methane, 1,1-bis[4-(3-aminophenoxy)phenyl]ethane, 1,2-bis[4-(3-aminophenoxy)phenyl]ethane, bis[4-(3-aminophenoxy)phenyl]sulfoxide, 4,4'-bis[3-(4-aminophenoxy)benzoyl]diphenyl ether, 4,4'-bis[3-(3-aminophenoxy)benzoyl]diphenyl ether, 4,4'-bis[4-(4-amino-α,α-dimethylbenzyl)phenoxy]benzophenone, 4,4'-bis[4-(4-amino-α,α-dimethylbenzyl)phenoxy]diphenyl sulfone, bis[4-{4-(4-aminophenoxy)phenoxy}phenyl]sulfone, 1,4-bis[4-(4-aminophenoxy)phenoxy-α,α-dimethylbenzyl]benzene, 1,3-bis[4-(4-aminophenoxy)phenoxy-α,α-dimethylbenzyl]benzene, 1,3-bis[4-(4-amino-6-trifluoromethylphenoxy)-α,α-dimethylbenzyl]benzene, 1,3-bis[4-(4-amino-6-fluorophenoxy)-α,α-dimethylbenzyl]benzene, 1,3-bis[4-(4-amino-6-methylphenoxy)-α,α-dimethylbenzyl]benzene, 1,3-bis[4-(4-amino-6-cyanophenoxy)-α,α-dimethylbenzyl]benzene, 3,3'-diamino-4,4'-diphenoxybenzophenone, 4,4'-diamino-5,5'-diphenoxybenzophenone, 3,4'-diamino-4,5'-diphenoxybenzophenone, 3,3'-diamino-4-phenoxybenzophenone, 4,4'-diamino-5-phenoxybenzophenone, 3,4'-diamino-4-phenoxybenzophenone, 3,4'-diamino-5'-phenoxybenzophenone, 3,3'-diamino-4,4'-dibiphenoxybenzophenone, 4,4'-diamino-5,5'-dibiphenoxybenzophenone, 3,4'-diamino-4,5'-dibiphenoxybenzophenone, 3,3'-diamino-4-biphenoxybenzophenone, 4,4'-diamino-5-biphenoxybenzophenone, 3,4'-diamino-4-biphenoxybenzophenone, 3,4'-diamino-5'-biphenoxybenzophenone, 1,3-bis(3-amino-4-phenoxybenzoyl)benzene, 1,4-bis(3-amino-4-phenoxybenzoyl)benzene, 1,3-bis(4-amino-5-phenoxybenzoyl)benzene, 1,4-bis(4-amino-5-phenoxybenzoyl)benzene, 1,3-bis(3-amino-4-biphenoxybenzoyl)benzene, 1,4-bis(3-amino-4-biphenoxybenzoyl)benzene, 1,3-bis(4-amino-5-biphenoxybenzoyl)benzene, 1,4-bis(4-amino-5-biphenoxybenzoyl)benzene, 2,6-bis[4-(4-amino-α,α-dimethylbenzyl)phenoxy]benzonitrile, and aromatic diamines in which some or all of the hydrogen atoms on the aromatic ring of the above aromatic diamines are substituted with a halogen atom, an alkyl group or alkoxyl group having 1 to 3 carbon atoms, a cyano group, or a halogenated alkyl group or alkoxyl group having 1 to 3 carbon atoms in which some or all of the hydrogen atoms of the alkyl group or alkoxyl group are substituted with a halogen atom, etc. can be mentioned.,

[0028] Examples of the aliphatic diamines include 1,2-diaminoethane, 1,4-diaminobutane, 1,5-diaminopentane, 1,6-diaminohexane, 1,8-diaminooctane and the like., Examples of the alicyclic diamines include 1,4-diaminocyclohexane, 4,4'-methylenebis(2,6-dimethylcyclohexylamine) and the like., The total amount of diamines other than aromatic diamines (aliphatic diamines and alicyclic diamines) is preferably 20% by mass or less of all diamines, more preferably 10% by mass or less, and still more preferably 5% by mass or less. In other words, the aromatic diamines are preferably 80% by mass or more of all diamines, more preferably 90% by mass or more, and still more preferably 95% by mass or more.,

[0029] As the tetracarboxylic acids constituting the polyamic acid, aromatic tetracarboxylic acids (including their acid anhydrides), aliphatic tetracarboxylic acids (including their acid anhydrides), and alicyclic tetracarboxylic acids (including their acid anhydrides) commonly used in polyimide synthesis can be used. Among them, aromatic tetracarboxylic anhydrides and alicyclic tetracarboxylic anhydrides are preferred. From the viewpoint of heat resistance, aromatic tetracarboxylic anhydrides are more preferred, and from the viewpoint of light transmittance, alicyclic tetracarboxylic acids are more preferred. When these are acid anhydrides, the number of anhydride structures in the molecule may be 1 or 2, but those having 2 anhydride structures (di-anhydrides) are preferably used. The tetracarboxylic acids may be used alone or in combination of two or more.

[0030] Examples of the alicyclic tetracarboxylic acids include alicyclic tetracarboxylic acids such as cyclobutane tetracarboxylic acid, 1,2,4,5-cyclohexane tetracarboxylic acid, 3,3’,4,4’-bicyclohexyltetracarboxylic acid, and their acid anhydrides. Among these, di-anhydrides having 2 anhydride structures (for example, cyclobutane tetracarboxylic di-anhydride, 1,2,4,5-cyclohexane tetracarboxylic di-anhydride, 3,3’,4,4’-bicyclohexyltetracarboxylic di-anhydride, etc.) are suitable. The alicyclic tetracarboxylic acids may be used alone or in combination of two or more. When transparency is emphasized, for example, 80% by mass or more of all the tetracarboxylic acids is preferably alicyclic tetracarboxylic acids, more preferably 90% by mass or more, and still more preferably 95% by mass or more.

[0031] The aromatic tetracarboxylic acids are not particularly limited, but are preferably those having a pyromellitic acid residue (i.e., those having a structure derived from pyromellitic acid), and more preferably their acid anhydrides. Examples of such aromatic tetracarboxylic acids include pyromellitic dianhydride, 3,3’,4,4’-biphenyltetracarboxylic dianhydride, 4,4’-oxydiphthalic dianhydride, 3,3’,4,4’-benzophenonetetracarboxylic dianhydride, 3,3’,4,4’-diphenylsulfonetetracarboxylic dianhydride, 2,2-bis[4-(3,4-dicarboxyphenoxy)phenyl]propane anhydride, and the like. When heat resistance is emphasized, for example, 80% by mass or more of all tetracarboxylic acids is preferable, more preferably 90% by mass or more, and still more preferably 95% by mass or more.

[0032] The thickness of the polymer film is preferably 3 μm or more, more preferably 11 μm or more, still more preferably 24 μm or more, and even more preferably 45 μm or more. The upper limit of the thickness of the polymer film is not particularly limited, but for use as a flexible electronic device, it is preferably 250 μm or less, more preferably 150 μm or less, and still more preferably 90 μm or less.

[0033] The average CTE of the polymer film between 30°C and 300°C is preferably -5 ppm / °C to +20 ppm / °C, more preferably -5 ppm / °C to +15 ppm / °C, and still more preferably 1 ppm / °C to +10 ppm / °C. When the CTE is within the above range, the difference in the linear expansion coefficient from a general support (inorganic substrate) can be kept small, and peeling between the polymer film and the inorganic substrate can be avoided even when subjected to a heat application process. Here, CTE is a factor representing reversible expansion and contraction with respect to temperature. The CTE of the polymer film refers to the average value of the CTE in the flow direction (MD direction) and the width direction (TD direction) of the polymer film. The measurement method of the CTE of the polymer film is according to the method described in the examples.

[0034] The thermal shrinkage rate of the polymer film between 30°C and 500°C is preferably ±0.9%, more preferably ±0.6%. The thermal shrinkage rate is a factor representing non-reversible expansion and contraction with respect to temperature.

[0035] The tensile break strength of the polymer film is preferably 60 MPa or more, more preferably 120 MPa or more, and even more preferably 240 MPa or more. The upper limit of the tensile break strength is not particularly limited, but is practically less than about 1000 MPa. When the tensile break strength is 60 MPa or more, it is possible to prevent the polymer film from breaking when peeling from the inorganic substrate. Note that the tensile break strength of the polymer film refers to the average value of the tensile break strength in the flow direction (MD direction) and the tensile break strength in the width direction (TD direction) of the polymer film. The method for measuring the tensile break strength of the polymer film is the method described in the examples.

[0036] The tensile elongation at break of the polymer film is preferably 1% or more, more preferably 5% or more, and even more preferably 20% or more. When the tensile elongation at break is 1% or more, the handleability is excellent. Note that the tensile elongation at break of the polymer film refers to the average value of the tensile elongation at break in the flow direction (MD direction) and the tensile elongation at break in the width direction (TD direction) of the polymer film. The method for measuring the tensile elongation at break of the polymer film is the method described in the examples.

[0037] The tensile modulus of the polymer film is preferably 3 GPa or more, more preferably 6 GPa or more, and even more preferably 8 GPa or more. When the tensile modulus is 3 GPa or more, the elongation deformation of the polymer film when peeling from the inorganic substrate is small, and the handleability is excellent. The tensile modulus is preferably 20 GPa or less, more preferably 12 GPa or less, and even more preferably 10 GPa or less. When the tensile modulus is 20 GPa or less, the polymer film can be used as a flexible film. The tensile modulus of the polymer film refers to the average value of the tensile modulus in the flow direction (MD direction) and the tensile modulus in the width direction (TD direction) of the polymer film. The measurement method of the tensile modulus of the polymer film is according to the method described in the examples.

[0038] The film thickness non-uniformity of the polymer film is preferably 20% or less, more preferably 12% or less, even more preferably 7% or less, and particularly preferably 4% or less. When the film thickness non-uniformity exceeds 20%, it tends to be difficult to apply to narrow parts. The film thickness non-uniformity of the film can be obtained, for example, by randomly extracting about 10 positions from the film to be measured with a contact type film thickness gauge to measure the film thickness, and calculating based on the following formula. Film thickness non-uniformity (%) = 100×(maximum film thickness - minimum film thickness)÷average film thickness

[0039] The polymer film is preferably obtained in a form wound as a long polymer film with a width of 300 mm or more and a length of 10 m or more during its production, and more preferably in the form of a roll-shaped polymer film wound around a winding core. When the polymer film is wound in a roll shape, transportation in the form of a heat-resistant polymer film wound in a roll shape becomes easy.

[0040] The shape of the laminate can be various shapes such as circular, square, etc. other than rectangular. When using a rectangular laminate, the heat-resistant polymer film is also mostly rectangular, and its size can be applied to various sizes, small or large, depending on the intended use. It is possible to produce even when the area is 0.65 square meters or more, and it is also possible that one side of the rectangle is at least 700 mm or more. A more preferable area for fabricating large-area devices is 0.7 square meters or more, and more preferably 1 square meter or more and 5 square meters or less, which is easier to fabricate. The lower limit is not particularly limited, and it is preferably 0.01 square meters or more, and more preferably 0.1 square meters or more. Also, a more preferable length of one side of the rectangle is 800 mm, and more preferably 900 mm or more. The lower limit is not particularly limited, but it is preferably 50 mm or more, and more preferably 100 mm or more.

[0041] In the polymer film, in order to ensure handleability and productivity, it is preferable to add and contain a lubricant (particles) having a particle diameter of about 10 to 1000 nm in the polymer film in an amount of about 0.03 to 3% by mass to impart fine irregularities to the surface of the polymer film to ensure slipperiness.

[0042] The inorganic substrate of the present invention may be any plate-shaped one that can be used as a substrate made of an inorganic substance. For example, a glass plate, a ceramic plate, a semiconductor wafer, a metal-based one, and a composite of these glass plates, ceramic plates, semiconductor wafers, and metals, such as those laminated, those in which these are dispersed, those containing these fibers, etc. can be mentioned. In the present invention, an inorganic substrate containing no nitrogen as a constituent element is preferably used.

[0043] Examples of the glass plate include quartz glass, high-silica glass (96% silica), soda-lime glass, lead glass, aluminosilicate glass, borosilicate glass (Pyrex (registered trademark)), borosilicate glass (alkali-free), borosilicate glass (micro sheet), aluminosilicate glass, etc. Among these, those with a linear expansion coefficient of 5 ppm / K or less are desirable. If they are commercially available products, "Corning (registered trademark) 7059", "Corning (registered trademark) 1737", "EAGLE" manufactured by Corning Inc., which are glass for liquid crystal, "AN100" manufactured by Asahi Glass Co., Ltd., "OA10", "OA11" manufactured by Nippon Electric Glass Co., Ltd., "AF32" manufactured by SCHOTT, etc. are desirable.

[0044] The semiconductor wafer is not particularly limited, and examples include silicon wafers, germanium, silicon-germanium, gallium-arsenic, aluminum-gallium-indium, nitrogen-phosphorus-arsenic-antimony, SiC, InP (indium phosphide), InGaAs, GaInNAs, LT, LN, ZnO (zinc oxide), CdTe (cadmium telluride), ZnSe (zinc selenide), etc. Among them, the wafer preferably used is a silicon wafer, and particularly preferably a mirror-polished silicon wafer with a size of 8 inches or more.

[0045] Examples of the metal include single-element metals such as W, Mo, Pt, Fe, Ni, Au, and alloys such as Inconel, Monel, Nimonic, carbon copper, Fe-Ni-based Invar alloy, Super Invar alloy, and steel (carbon steel). Also included are multi-layer metal plates formed by adding other metal layers or ceramic layers to these metals. In this case, if the overall linear expansion coefficient (CTE) with the additional layer is low, Cu, Al, etc. can also be used for the main metal layer. The metal used as the additional metal layer is not limited as long as it has characteristics such as strong adhesion to the polymer film, no diffusion, good chemical resistance, and good heat resistance. Suitable examples include Cr, Ni, TiN, Cu containing Mo, etc.

[0046] The planar portion of the inorganic substrate needs to be flat to a certain extent. The surface roughness Ra of part or all of the surface of the inorganic substrate is preferably 1 nm or more, more desirably 3 nm or more, preferably 1000 nm or less, more desirably 600 nm or less, and even more desirably 100 nm or less. Within this range, the polymer film can be stably bonded. If it is coarser than this, the adhesion strength between the polymer film layer and the inorganic substrate may be insufficient. The surface roughness Ra of the inorganic substrate is the value before bonding with the polymer film.

[0047] The thickness of the inorganic substrate is not particularly limited, but from the perspective of handleability, a thickness of 10 mm or less is preferred, 3 mm or less is more preferred, and 1.3 mm or less is even more preferred. There is no particular limitation on the lower limit of the thickness, but it is preferably 0.05 mm or more, more preferably 0.3 mm or more, and even more preferably 0.5 mm or more.

[0048] The silane coupling agent (SCA) of the present invention physically or chemically intervenes between the inorganic substrate and the metal-containing layer and has the function of bonding the inorganic substrate and the polymer film. The silane coupling agent used in the present invention includes at least a coupling agent having an amino group. Preferred specific examples of the silane coupling agent 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, and the like.

[0049] Among the silane coupling agents, a silane coupling agent having one silicon atom in one molecule is particularly preferred. For example, 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. may be mentioned. When particularly high heat resistance is required in the process, those in which an aromatic group connects between Si and the amino group are desirable. As the coupling agent, in addition to the above, 11-amino-1-undecene thiol can also be used.

[0050] As a method for forming the silane coupling agent layer, a method of applying a silane coupling agent solution to the inorganic substrate, a vapor deposition method, etc. can be used. In addition, the formation of the silane coupling agent layer may be performed on the surface of the heat-resistant polymer.

[0051] As a method for applying the silane coupling agent solution, a solution obtained by diluting a silane coupling agent with a solvent such as alcohol is used, and conventionally known solution application means such as 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, spray coating method, etc. can be appropriately used.

[0052] Also, the silane coupling agent layer can be formed by a vapor deposition method. Specifically, it is formed by exposing the inorganic substrate to the vapor of the silane coupling agent, that is, the silane coupling agent in a substantially gaseous state. The vapor of the silane coupling agent can be obtained by heating the liquid state silane coupling agent to a temperature ranging from 40°C to about the boiling point of the silane coupling agent. The boiling point of the silane coupling agent varies depending on its chemical structure, but generally ranges from 100 to 250°C. However, heating above 200°C is not preferable because it may cause side reactions on the organic group side of the silane coupling agent. The environment for heating the silane coupling agent may be under pressure, normal pressure, or reduced pressure. However, normal pressure or reduced pressure is preferable when promoting the vaporization of the silane coupling agent. Since many silane coupling agents are flammable liquids, it is preferable to perform the vaporization operation in a sealed container, preferably after replacing the inside of the container with an inert gas. The time for exposing the inorganic substrate to the silane coupling agent is not particularly limited, but preferably within 20 hours, more preferably within 60 minutes, still more preferably within 15 minutes, and most preferably within 10 minutes. The temperature of the inorganic substrate during the exposure of the inorganic substrate to the silane coupling agent is preferably controlled to an appropriate temperature between -50°C and 200°C depending on the type of the silane coupling agent and the required thickness of the silane coupling agent layer.

[0053] The film thickness of the silane coupling agent layer is extremely thin compared to an inorganic substrate, a polymer film, etc., and from a mechanical design perspective, the thickness between the highest part of the inorganic substrate and the polymer film surface is negligible. In principle, a thickness on the order of a monolayer is sufficient. However, since it is necessary to fill the rough surface, the film thickness needs to be effectively thick. That is, a silane coupling agent in an amount corresponding to the volume of the rough surface of the inorganic substrate is required. Since there is a very thin layer on the rough surface, it is often difficult to measure the film thickness. The film thickness of the silane coupling agent layer is generally less than 20 nm from the upper end of the inorganic substrate, preferably 15 nm or less, more preferably 10 nm or less in practical use, even more preferably 7 nm or less, and still more preferably 5 nm or less. However, when the silane coupling agent layer exists in a cluster form rather than as a uniform coating film, the adhesion area with the polymer film decreases, which is not desirable. Note that the film thickness of the silane coupling agent layer can be determined by calculation from the concentration and coating amount of the silane coupling agent solution during coating.

[0054] In the laminate of the present invention, an inorganic substrate, an amino group-containing silane coupling agent layer, and a heat-resistant polymer film are laminated in this order, and the nitrogen element ratio of the peeling surface of the inorganic substrate after peeling the heat-resistant polymer film from the inorganic substrate at 90° needs to exceed 3.5 atomic %. Preferably it is 4 atomic % or more, more preferably 5 atomic % or more. Also, it is 11 atomic % or less. Preferably it is 9 atomic % or less, more preferably 8 atomic % or less. When the nitrogen element ratio is within the above range, the adhesion strength between the heat-resistant polymer film and the inorganic substrate can be uniformly and appropriately controlled. Also, it prevents the generation of bubbles between the inorganic substrate and the polymer film.

[0055] The laminate of the present invention preferably has a blister defect density of 5 or less per square meter. More preferably it is 4 or less, and still more preferably 3 or less. The lower limit is not particularly limited, but industrially it may be 1 or more. If it is within the above range, a high-quality laminate can be obtained.

[0056] Such a laminate can be obtained by a lamination method characterized by preferably performing the following steps in this order: [Method A] (1) A step of applying a silane coupling agent containing an amino group to at least one surface of an inorganic substrate; (2) A step of supplying an aqueous medium to the surface of the inorganic substrate to which the silane coupling agent is applied and / or the adhesive surface side of the heat-resistant polymer film; (3) A step of overlapping the surface of the inorganic substrate to which the silane coupling agent is applied with the heat-resistant polymer film; (4) A step of pressing the two while extruding the aqueous medium from between the surface of the inorganic substrate to which the silane coupling agent is applied and the adhesive surface of the heat-resistant polymer film. It can be obtained by a lamination method characterized by preferably performing the steps in this order. In addition, in the present invention, [Method B] (1) A step of applying a silane coupling agent containing an amino group to at least one surface of a heat-resistant polymer film; (2) A step of supplying an aqueous medium to the adhesive surface side of the inorganic substrate and / or the surface of the heat-resistant polymer film to which the silane coupling agent is applied; (3) A step of overlapping the inorganic substrate with the surface of the heat-resistant polymer film to which the silane coupling agent is applied; (4) A step of pressing the two while extruding the aqueous medium from between the adhesive surface of the inorganic substrate and the surface of the heat-resistant polymer film to which the silane coupling agent is applied. It can be obtained by a lamination method characterized by preferably performing the steps in this order.

[0057] As the aqueous medium, water or a mixed medium of water and a water-soluble solvent can be used. As the water-soluble solvent, lower alcohols, low-molecular ketones, or tetrahydrofuran can be used. Preferred aqueous media are pure water, a mixed solvent of water and methanol, a mixed solvent of water and ethanol, a mixed solvent of water, isopropanol, and methyl ethyl ketone, a mixed solvent of water and tetrahydrofuran, etc. An aqueous medium particularly preferably used in the present invention is water, a monohydric alcohol, a dihydric alcohol, a trihydric alcohol that is liquid at room temperature, or a mixture having two or more of these components. Further, a trace amount of surfactant may be added to the aqueous medium in order to improve the wettability between the aqueous medium and the inorganic substrate or the polymer film.

[0058] As a method of wetting the adhesion surface of the substrate or the film with the aqueous medium, existing methods such as dropping with a dropper or a dispenser, discharging from a valve, or spraying in a mist form from a spray nozzle can be applied. Further, immersing the substrate or the film in the aqueous medium is also an effective means for wetting. In addition, when a liquid containing water or alcohol is used as the aqueous medium, it also contributes to the promotion of the reaction of the silane coupling agent.

[0059] As a method of bonding the inorganic substrate and the heat-resistant polymer film, a pressing method, a roll laminator method, etc. can be applied. For example, pressure can be applied in a planar or linear manner by pressing, laminating, or roll laminating under an atmospheric pressure atmosphere or in a vacuum. Further, the process can also be promoted by heating during pressurization. In the present invention, pressing or roll laminating under an atmospheric atmosphere is preferred, and particularly a method using a roll (such as roll laminating) is preferred because the aqueous medium at the adhesion interface can be sequentially extruded from the adhesion surface during bonding.

[0060] As the pressure during pressurization (pressurization treatment), 0.1 MPa to 20 MPa is preferable, and more preferably 0.2 MPa to 3 MPa. When it is 20 MPa or less, breakage of the inorganic substrate can be suppressed. Also, when it is 0.1 MPa or more, the occurrence of non-adhering parts and insufficient adhesion can be prevented. It is also preferable to perform heating (pressurization heating treatment) during the pressurization treatment. As the temperature during the pressurization heating treatment, it is preferably 80°C to 400°C, and more preferably 100°C to 200°C. If the temperature is too high, there is a risk of damaging the polymer film, and if the temperature is too low, the adhesion strength tends to be weak. Also, the pressurization heating treatment can be carried out in an atmospheric pressure atmosphere as described above, but it may be possible to obtain more uniform adhesion when carried out under vacuum. As the degree of vacuum, the degree of vacuum by an ordinary rotary oil pump is sufficient, and about 10 Torr or less is sufficient. As an apparatus that can be used for the pressurization heating treatment, for example, "11FD" manufactured by Imoto Seisakusho can be used for performing a press in a vacuum, and for performing a vacuum lamination such as a roll-type film laminator in a vacuum or a film laminator that applies pressure to the entire glass surface at once with a thin rubber film after evacuating to vacuum, for example, "MVLP" manufactured by Meiki Seisakusho can be used.

[0061] The pressurization heating treatment can be performed separately into a pressurization process and a heating process. In this case, first, the polymer film and the inorganic substrate are pressurized (preferably about 0.2 to 50 MPa) at a relatively low temperature (for example, less than 120°C, more preferably 80°C or more and 110°C or less) to ensure adhesion between the two, and then, heating is performed at a relatively high temperature (for example, 80°C or more, more preferably 100°C to 250°C, even more preferably 120°C to 220°C) under pressure (preferably 20 MPa or less, 0.2 MPa or more) or at normal pressure, whereby the chemical reaction at the adhesion interface is promoted and the polymer film and the inorganic substrate can be laminated.

[0062] As described above, a laminate in which the inorganic substrate and the polymer film are bonded together can be obtained. However, the method for manufacturing the laminate according to the present invention is not limited to this example. As another example, pure water may be dropped onto the heat-resistant polymer film side, and at almost the same time as the silane coupling agent layer becomes a desirable silane coupling agent layer by contacting water when laminated, the inorganic substrate may be bonded. Also, pure water may be dropped onto both the heat-resistant polymer film side and the inorganic substrate to promote the reaction of the silane coupling agent and achieve a desired bonding state. The inorganic substrate may be bonded in this way.

[0063] Thus, as a preferred embodiment of the laminate in the present invention, the initial 90-degree adhesion strength between the heat-resistant polymer film and the inorganic substrate is 0.06 N / cm or more and 0.25 N / cm or less, the blister defect density is 5 or less per square meter, preferably the area is 0.65 square meters or more and the length of at least one side is 700 mm or more, and a laminate can be obtained.

[0064] When peeling the heat-resistant polymer film from the laminate, the adhesion strength by the 90° peeling method (hereinafter also referred to as the initial 90-degree adhesion strength) of the laminate is preferably 0.06 N / cm or more, more preferably 0.09 N / cm or more, and even more preferably 0.1 N / cm or more. Also, the initial 90-degree adhesion strength is preferably 0.25 N / cm or less, and more preferably 0.2 N / cm or less. When the initial 90-degree adhesion strength is 0.06 N / cm or more, it is possible to prevent the heat-resistant polymer film from peeling off from the inorganic substrate before or during device formation. Also, when the initial 90-degree adhesion strength is 0.25 N / cm or less, it is easy to peel the inorganic substrate and the heat-resistant polymer film after device formation. That is, when the initial 90-degree adhesion strength is 0.25 N / cm or less, even if the adhesion strength between the inorganic substrate and the heat-resistant polymer film slightly increases during device formation, it is easy to peel them. In this specification, the initial 90-degree adhesion strength refers to the 90-degree adhesion strength between the inorganic substrate and the heat-resistant polymer film after heat-treating the laminate at 200 °C for 1 hour in an air atmosphere.

[0065] The measurement conditions for the initial adhesion strength at 90 degrees are as follows. Peel the heat-resistant polymer film from the inorganic substrate at an angle of 90 degrees. Perform the measurement five times, and take the average value as the measured value. Measurement temperature: Room temperature (25 °C) Peeling speed: 100 mm / min Atmosphere: Air Measurement sample width: 2.5 cm More specifically, it is based on the method described in the examples.

[0066] In this specification, in addition to the initial adhesion strength, it is preferable that the adhesion strength after heat treatment is also within the above range. The adhesion strength after heat treatment refers to the 90-degree adhesion strength between the inorganic substrate and the heat-resistant polymer film after the laminate is heat-treated at 200 °C for 1 hour and then further heat-treated at 450 °C for 1 hour in an air atmosphere.

[0067] In this specification, "adhesion strength" means both "initial adhesion strength" and "adhesion strength after heat treatment". That is, "the adhesion strength is 0.06 N / cm or more and 0.25 N / cm or less" means that "the initial adhesion strength is 0.06 N / cm or more and 0.25 N / cm or less" and "the adhesion strength after heat treatment is 0.06 N / cm or more and 0.25 N / cm or less".

[0068] In the present invention, a functional element is formed on the surface of the laminate obtained by the above Method A or Method B, which is opposite to the adhesive surface of the heat-resistant polymer film, and after the formation, the heat-resistant polymer film together with the functional element is peeled off from the inorganic substrate to fabricate a flexible electronic device.

[0069] As used herein, an electronic device refers to an electronic circuit including a wiring board having a single-sided, double-sided, or multilayer structure for carrying electrical wiring, active elements such as transistors and diodes, and passive devices such as resistors, capacitors, and inductors. Additionally, it includes sensor elements for sensing pressure, temperature, light, humidity, etc., biosensor elements, light-emitting elements, image display elements such as liquid crystal displays, electrophoretic displays, and self-emitting displays, communication elements by wireless or wired means, arithmetic elements, memory elements, MEMS elements, solar cells, thin-film transistors, and the like.

[0070] In the method for manufacturing a flexible electronic device according to this specification, after forming an electronic device on the polymer film surface of the laminate fabricated by the method described above, the polymer film is peeled off from the inorganic substrate.

[0071] The method for peeling the polymer film with the electronic device formed thereon from the inorganic substrate is not particularly limited. For example, a method of rolling from the edge with tweezers or the like, a method of making a cut in the polymer film, attaching an adhesive tape to one side of the cut portion, and then rolling from that tape portion, a method of vacuum-adsorbing one side of the cut portion of the polymer film and then rolling from that portion, etc. can be adopted. When peeling, if a bend with a small curvature occurs in the cut portion of the polymer film, stress will be applied to the device in that portion, which may damage the device. Therefore, it is desirable to peel in a state with as large a curvature as possible. For example, it is desirable to roll while winding around a roll with a large curvature, or to roll using a machine configured such that a roll with a large curvature is positioned at the peeling portion. As a method of making a cut in the polymer film, there are a method of cutting the polymer film with a cutting tool such as a blade, a method of cutting the polymer film by relatively scanning a laser and a laminate, a method of cutting the polymer film by relatively scanning a water jet and a laminate, a method of cutting the polymer film while cutting into a glass layer slightly with a dicing device for semiconductor chips, etc., but the method is not particularly limited. For example, when adopting the above-described method, techniques such as superimposing ultrasonic waves on the cutting tool, adding a reciprocating motion or an up-and-down motion, etc. to improve the cutting performance can be appropriately adopted. Also, a method of attaching another reinforcing base material in advance to the portion to be peeled off and peeling off together with the reinforcing base material is also useful. When the flexible electronic device to be peeled off is the backplane of the display device, it is also possible to attach the front plane of the display device in advance, integrate them on the inorganic substrate, and then peel them off simultaneously to obtain a flexible display device.

Examples

[0072] Hereinafter, the present invention will be described in detail using examples, but the present invention is not limited to the following examples as long as the gist thereof is not exceeded.

[0073] Each measured value in the examples and comparative examples was measured by the following method unless otherwise specified.

[0074] <Thickness of heat-resistant polymer film> It was measured using a micrometer (manufactured by Fine Ryufu Co., Ltd., Millitron 1245D).

[0075] <Tensile elastic modulus, tensile fracture strength, and tensile fracture elongation of heat-resistant polymer film> A strip-shaped sample measuring 100 mm × 10 mm was cut out in the machine direction (MD direction) and the transverse direction (TD direction) of the polymer film and used as a test piece. The test piece was cut out from the central part in the transverse direction. Using a tensile testing machine (manufactured by Shimadzu Corporation, Autograph (R), model name AG-5000A), the tensile elastic modulus, tensile breaking strength, and tensile breaking elongation were measured in the MD direction and TD direction respectively under the conditions of a temperature of 25°C, a tensile speed of 50 mm / min, and a chuck distance of 40 mm.

[0076] <Coefficient of Thermal Expansion (CTE)> In the machine direction (MD direction) and the transverse direction (TD direction) of the polymer film, the expansion and contraction rate was measured under the following conditions, and the expansion and contraction rate / temperature at 15°C intervals such as 30°C to 45°C and 45°C to 60°C was measured. This measurement was carried out up to 300°C, and the average value of all measurement values was calculated as the CTE. Equipment name; TMA4000S manufactured by MAC Science Co., Ltd. Sample length; 20 mm Sample width; 2 mm Initial temperature for temperature rise; 25°C Final temperature for temperature rise; 400°C Temperature rise rate; 5°C / min Atmosphere; Argon

[0077] <Measurement of Adhesion Strength> The adhesion strength of the polymer film from the laminate obtained in the production of the laminate was determined by the 90-degree peel method in the following manner. The film was peeled off from the inorganic substrate at an angle of 90 degrees. Measuring device; Autograph AG-IS manufactured by Shimadzu Corporation Measuring temperature; Room temperature (25°C) Peeling speed; 100 mm / min Atmosphere; Air Measured sample width; 2.5 cm In addition, the measurement was carried out at a total of 5 points including the central part and the four corners of the laminate, and the average value was obtained.

[0078] <Counting of Blister Defects> In the present invention, those with a major axis of 300 μm or more were counted as blisters. A blister is also called a floating defect or a bubble defect, and is a location where the film floats in a bubble shape without adhering to the substrate, and is often caused by lifting the film in a tent shape by sandwiching a relatively hard foreign object. In the present invention, focusing on the adhesion surface between the inorganic substrate and the polymer film, the laminate was observed at an enlarged scale, and the number of blisters with a major axis of 300 μm or more was at least For the G2 (370 mm × 470 mm) size laminate, 4 sheets For the G4.5 (730 mm × 920 mm) size laminate, 2 sheets For the G5 (1100 mm × 1250 mm) size laminate, 1 sheet were counted and converted to the number per square meter.

[0079] <Nitrogen element component ratio> A 50 mm × 50 mm range of the peeling surface obtained by peeling the polymer film from the laminate at 90° was analyzed by ESCA to evaluate the ratio of nitrogen element present on the peeling surface of the inorganic substrate. The apparatus used was K-Alpha + (manufactured by Thermo Fisher Scientific). The measurement conditions are as follows. In the analysis, background removal was performed by the Shirley method. Also, the surface composition ratio was taken as the average value of the measurement results at three or more locations. ·Measurement conditions Excitation X-ray: Monochromatized Al Kα ray X-ray output: 12 kV, 6 mA Photoelectron escape angle: 90 ° Spot size: 400 μmφ Pass energy: 50 eV Step: 0.1 eV

[0080] <Surface roughness Ra of the inorganic substrate> The measurement of Ra was performed using a confocal microscope (HYBRID C3 manufactured by Lasertec). Measurement was carried out in the Blue mode with a scan resolution of 0.06 μm at a magnification of 50 times of the objective lens. The measurement (observation) was carried out in a square area of approximately 300 μm for both X and Y. For the SUS substrate, the edges were made not to enter the measurement range. After confirming that the Ra value does not change depending on the position any further, the measurement was carried out without specifying the position in particular.

[0081] [Preparation of Polyamic Acid Solution A] After purging the inside of a reaction vessel equipped with a nitrogen introduction tube, a thermometer, and a stirrer with nitrogen, 223 parts by mass of 5-amino-2-(p-aminophenyl)benzoxazole (DAMBO) and 4416 parts by mass of N,N-dimethylacetamide were added to the reaction vessel and completely dissolved. Next, together with 217 parts by mass of pyromellitic dianhydride (PMDA), 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 became 0.7% by mass based on the total polymer solid content in the polyamic acid solution A, and the mixture was stirred at a reaction temperature of 25 °C for 24 hours to obtain a brown and viscous polyamic acid solution A.

[0082] [Production Example 1 of Polyimide Film] The polyamic acid solution A was applied using a die coater onto an endless continuous belt made of mirror-finished stainless steel (coating width 1240 mm) and dried at 90 to 115 °C for 10 minutes. After drying, the self-supporting polyamic acid film was peeled off from the support and both ends were cut to obtain a green film. The obtained green film was conveyed by a pin tenter so that the final pin sheet interval became 1140 mm, and heat treatment was performed at 170 °C for 2 minutes in the first stage, 230 °C for 2 minutes in the second stage, and 465 °C for 6 minutes in the third stage to advance the imidization reaction. Then, it was cooled to room temperature in 2 minutes, and the portions with poor planarity at both ends of the film were cut off with a slitter and wound up in a roll to obtain the polyimide film 1 shown in Table 1.

[0083] [Production Example 2 of Polyimide Film] Except for changing the gap of the die coater so that the resulting polyimide film thickness becomes 38 μm, the same operations were carried out, and the polyimide film 2 shown in Table 1 was obtained.

[0084] 〔Polyimide Film 3〕 The polyimide film Upilex25S (registered trademark) with a thickness of 25 μm manufactured by Ube Industries was used as the polyimide film 3.

[0085] <Fabrication of Laminated Body> (Example 1) First, the polyimide film 1 obtained in Preparation Example 1 was cut out to a width of 370 mm × 500 mm. Next, as a film surface treatment, UV / O3 irradiation was performed for 3 minutes using a UV / O3 irradiator (SKR1102N-03 manufactured by LAN Technical). At this time, the distance between the UV / O3 lamp and the film was 30 mm.

[0086] Using the apparatus shown in the schematic diagram in Fig. 1, an amino group-containing silane coupling agent was applied to a G2-sized inorganic substrate (370 mm × 470 mm, SUS substrate with a thickness of 0.7 mm) through the gas phase. As the inorganic substrate, one that had been subjected to pure water washing, drying, and then dry cleaning by irradiation with a UV / O3 irradiator (SKR1102N-03 manufactured by LAN Technical) for 1 minute was used. The inorganic substrate was placed stationary in the chamber of the apparatus. 130 g of 3-aminopropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., KBM-903) was put into a chemical solution tank with a capacity of 1 L. The outer water bath was heated to 42 °C, and the generated silane coupling agent vapor was sent into the chamber together with clean dry air at a gas flow rate of 22 L / min, exposing the inorganic substrate to the silane coupling agent vapor. At this time, the substrate temperature was 21 °C, the temperature of the clean dry air was 23 °C, and the humidity was 1.2%RH. Since the exhaust was connected to a negative pressure exhaust port, it was confirmed with a differential pressure gauge that the chamber had a negative pressure of about 10 Pa.

[0087] In this way, the inorganic substrate coated with the amino group-containing silane coupling agent was set in a roll laminator equipped with a silicon rubber roller. First, 100 ml of pure water was dropped onto the surface coated with the silane coupling agent with a dropper so as to spread over the entire substrate as an aqueous medium, and the substrate was wetted.

[0088] Next, the surface-treated surface of the polyimide film was overlapped so as to face the surface coated with the silane coupling agent of the inorganic substrate, that is, the surface wetted with pure water. While sequentially extruding the pure water between the polyimide film and the inorganic substrate with a rotating roll from one side of the inorganic substrate, pressure was applied to laminate the inorganic substrate and the polyimide film to obtain a temporary laminate. The laminator used was a laminator manufactured by MCK with an effective roll width of 1350 mm. The bonding conditions were: air source pressure: 0.5 MPa, lamination speed: 50 mm / second, roll temperature: 22°C, environmental temperature 22°C, and humidity 55%RH. The obtained temporary laminate was heat-treated in a clean oven at 200°C for 10 minutes to obtain the laminate in the present invention. The same operation was carried out for 4 inorganic substrates. The evaluation results of the obtained laminate are shown in Table 2.

[0089] (Examples 2 to 20, Comparative Examples 1 to 4) Subsequently, laminates were produced under the conditions shown in Tables 2 to 5 in the same manner, and the properties of the laminates were evaluated. The results are shown in Tables 2 to 5. The films, inorganic substrates, and aqueous media used in the tables were as follows. Note 1 in the table indicates that since the film and the inorganic substrate did not adhere, the peeling surface could not be defined and the nitrogen element component ratio could not be measured. Film 1: The polyimide film obtained in Production Example 1 of the polyimide film Film 2: The polyimide film obtained in Production Example 2 of the polyimide film Film 3: Polyimide film Upilex25S (registered trademark) manufactured by Ube Industries, Ltd. Glass: OA10G manufactured by Nippon Electric Glass Co., Ltd. The size of the inorganic substrate is as follows. All of the SUS substrate (surface roughness Ra is 45 nm), steel (carbon steel) substrate (surface roughness Ra is 35 nm), Cu substrate (surface roughness Ra is 14 nm), and glass substrate (surface roughness Ra is 0.6 nm) have the same size. G2 size (370 mm × 470 mm) G4.5 size (730 mm × 920 mm) G5 size (1100 mm × 1250 mm) Aqueous medium Pure water: Ultrapure water Pure water + MeOH: 99 parts pure water / 1 part methanol (by mass) Pure water + EtOH: 99 parts pure water / 1 part ethanol (by mass) It is.

[0090]

Table 1

[0091]

Table 2

[0092]

Table 3

[0093]

Table 4

[0094]

Table 5

[0095] <Application Example (Fabrication of Flexible Electronic Devices)> Using the laminate obtained in Example 15, a tungsten film (film thickness: 75 nm) was formed on a polyimide film by vacuum evaporation through the following steps. Then, without exposing to air, a silicon oxide film (film thickness: 150 nm) was laminated as an insulating film. Next, a silicon oxynitride film (film thickness: 100 nm) serving as an underlying insulating film was formed by plasma CVD method. Then, without exposing to air, an amorphous silicon film (film thickness: 54 nm) was laminated.

[0096] Next, the hydrogen element in the amorphous silicon film was removed to promote crystallization, and a heat treatment at 500 °C was performed for 40 minutes to form a polysilicon film. A TFT element was fabricated using the obtained polysilicon film. First, the polysilicon thin film was patterned to form a silicon region with a predetermined shape. Appropriately, formation of a gate insulating film, formation of a gate electrode, formation of a source region or a drain region by doping the active region, formation of an interlayer insulating film, formation of source and drain electrodes, and activation treatment were performed to fabricate an array of P-channel TFTs using polysilicon. The polymer film portion was cut with a UV-YAG laser along the inner side about 0.5 mm from the outer periphery of the TFT array, and peeling was performed so as to scoop up using a thin razor-like blade from the edge of the cut, and a flexible A3-size TFT array was obtained. The peeling angle at this time was 3 degrees. The peeling was possible with extremely small force and it was possible to peel without damaging the TFT. The obtained flexible TFT array maintained good characteristics without showing performance degradation even when wound around a 3-mmφ round bar.

Industrial Applicability

[0097] As described above, the method for manufacturing the laminate of the present invention and the laminate obtained therefrom can realize a stable and uniform low adhesive strength even for a large area, and the occurrence of blister defects is extremely low. Therefore, it is extremely useful as a temporary support substrate for manufacturing high-quality and large-area flexible devices.

Explanation of Reference Numerals

[0098] 1. Flow meter 2. Gas inlet 3. Chemical liquid tank (silane coupling agent tank) 4. Warm water tank (hot water bath) 5. Heater 6. Treatment chamber (chamber) 7. Substrate to be coated 8. Exhaust port

Claims

1. (1) A step of applying a silane coupling agent containing an amino group to at least one surface of an inorganic substrate; (2) A step of supplying an aqueous medium to the surface of the inorganic substrate coated with the silane coupling agent and / or the adhesive surface side of the heat-resistant polymer film; (3) A step of overlapping the surface of the inorganic substrate coated with the silane coupling agent and the heat-resistant polymer film; (4) A step of pressing both while extruding the aqueous medium from between the surface of the inorganic substrate coated with the silane coupling agent and the adhesive surface of the heat-resistant polymer film; A method for manufacturing a laminate having, in this order, an inorganic substrate, a silane coupling agent layer containing an amino group, and a heat-resistant polymer film, characterized by having at least the above steps.

2. (1) A step of applying a silane coupling agent containing an amino group to at least one surface of a heat-resistant polymer film; (2) A step of supplying an aqueous medium to the adhesive surface side of the inorganic substrate and / or the surface of the heat-resistant polymer film coated with the silane coupling agent; (3) A step of overlapping the inorganic substrate and the surface of the heat-resistant polymer film coated with the silane coupling agent; (4) A step of pressing both while extruding the aqueous medium from between the adhesive surface of the inorganic substrate and the surface of the heat-resistant polymer film coated with the silane coupling agent; A method for manufacturing a laminate having, in this order, an inorganic substrate, a silane coupling agent layer containing an amino group, and a heat-resistant polymer film, characterized by having at least the above steps.

3. A method for manufacturing a flexible electronic device, comprising a step of forming a functional element on the surface of the laminate obtained by the manufacturing method according to Claim 1 or 2, which is opposite to the adhesive surface of the heat-resistant polymer film and the inorganic substrate.

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