Laminate, method for manufacturing laminate, and method for manufacturing flexible electronic device

Abstract

To provide a laminate that is useful as a temporary support for producing a large-area, high-definition, flexible electronic device, has a stably low adhesive strength between a heat-resistant polymer film and an inorganic substrate even in a case of a large surface area, and has few blister defects.SOLUTION: There is provided a laminate, comprising: an inorganic substrate; a silane coupling agent layer including an amino group; and a heat-resistant polymer film in the stated order, the laminate being characterized in that an elemental nitrogen component ratio in an inorganic-substrate-side peel surface after peeling the heat-resistant polymer film from the inorganic substrate at 90° is greater than 3.5 atomic% and 11 atomic% or less.SELECTED DRAWING: None

Description

[Technical Field]

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

[0002] In recent years, there has been active development of technologies for forming functional elements such as semiconductor elements, MEMS elements, and display elements on polymer films, with the aim of making these elements lighter, smaller, thinner, and more flexible. Traditionally, ceramics have been used as the base material for electronic components in information and communications equipment (broadcasting equipment, mobile radio, portable communications equipment, etc.), radar, high-speed information processing devices, and other such equipment. These materials are heat-resistant and can handle the increasingly high signal frequencies (reaching the GHz range) of information and communications equipment. However, ceramics are not flexible and are difficult to make thin, limiting the fields in which they can be used. Therefore, polymer films have recently been used as substrates.

[0003] The ideal method for fabricating functional elements, such as semiconductor, MEMS, and display elements, on polymer film surfaces is to use the roll-to-roll process, which takes advantage of the flexibility of polymer films. However, in the semiconductor, MEMS, and display industries, process technologies have been developed for rigid, planar substrates, such as wafers or glass substrates. Therefore, to fabricate functional elements on polymer films using existing infrastructure, a process is used in which the polymer film is bonded to a rigid inorganic substrate (such as a glass plate, ceramic plate, silicon wafer, or metal plate), and the desired elements are fabricated on the substrate, followed by peeling.

[0004] In the process of forming a desired functional device on a laminate formed by bonding a polymer film to an inorganic support, the laminate is often exposed to high temperatures. For example, the formation of functional devices such as polysilicon or oxide semiconductors requires processes in the temperature range of approximately 200°C to 600°C. Furthermore, the production of hydrogenated amorphous silicon thin films may require temperatures of approximately 200°C to 300°C, and further heating of amorphous silicon to dehydrogenate it to low-temperature polysilicon may require heating at approximately 450°C to 600°C. Therefore, heat resistance is required for the polymer film constituting the laminate, but in reality, only limited polymer films can withstand such high temperatures. Furthermore, while adhesives or glues are generally used to bond polymer films to supports, the bonding surface between the polymer film and the support (i.e., the adhesive or glue used for bonding) also requires heat resistance. However, typical adhesives and glues used for bonding do not have sufficient heat resistance, and therefore bonding using adhesives or glues is not applicable when the temperature required for forming functional devices is high.

[0005] Due to the lack of adhesives or pressure-sensitive adhesives with sufficient heat resistance, the conventional technique for the above-mentioned applications involves applying a polymer solution or a polymer precursor solution to an inorganic substrate, drying and curing the solution on the inorganic substrate to form a film for use in the application. However, the polymer film obtained by this method is brittle and prone to tearing, and functional elements formed on the polymer film surface are often destroyed when peeled from the inorganic substrate. Peeling a large-area film from an inorganic substrate is particularly difficult, making it impossible to achieve an industrially viable yield. In view of these circumstances, a laminate of a polymer film and an inorganic substrate has been proposed for producing a so-called flexible electronic device, in which a functional element is formed on a flexible substrate. The laminate is formed by bonding a polyimide film, which has excellent heat resistance, is strong, and can be thinned, to an inorganic substrate via a silane coupling agent (see, for example, Patent Documents 1 to 3). [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent No. 5152104 [Patent Document 2] Patent No. 5304490 [Patent Document 3] Patent No. 5531781 Summary of the Invention [Problem to be solved by the invention]

[0007] In the above-described laminate, a layer containing a silane coupling agent is interposed between the inorganic substrate and the heat-resistant polymer film, thereby preventing the inorganic substrate from peeling off from the polyimide film before or during device formation, and enabling the inorganic substrate to be easily peeled off from the polyimide film after device formation. However, because the adhesive strength between the polymer film and inorganic substrate varies depending on the thickness of the silane coupling agent, it is extremely difficult to control the adhesive strength of both companies to achieve uniform adhesive strength over a large area. In other words, it is difficult to apply the silane coupling agent to a uniform thickness on large substrates, and this is particularly true for glass substrates measuring 730mm x 920mm or larger, known as 4.5th generation, compared to 4th generation (660mm x 800mm) sizes, posing many problems in industrial production. [Means for solving the problem]

[0008] In view of these circumstances, the present inventors have conducted extensive research and have found a manufacturing method that allows the thickness of the silane coupling agent to be easily controlled to be extremely thin and uniform, even for large areas exceeding the 4.5 generation size, and that enables the production of high-quality laminates with few blister defects. Furthermore, the manufacturing method of the present invention has led to the realization of a laminate in which a heat-resistant polymer film and an inorganic substrate are laminated with an extremely uniform, extremely thin silane coupling agent layer, and further, the inventors have found that high-quality flexible electronic devices can be produced using such laminates. That is, the present invention has the following configuration. [1] 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 in that after peeling the heat-resistant polymer film 90° from the inorganic substrate, the nitrogen element ratio of the peeled surface on the inorganic substrate side is more than 3.5 atomic % and 11 atomic % or less. [2] The laminate according to [1], characterized in that the adhesive strength when peeling the heat-resistant polymer film from the laminate by a 90° peeling method 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], characterized in that the density of blister defects 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, has an area of 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) supplying an aqueous medium to the silane coupling agent-coated surface of the inorganic substrate and / or the adhesive surface of the heat-resistant polymer film; (3) a step of overlaying a heat-resistant polymer film on the silane coupling agent-coated surface of the inorganic substrate; (4) a step of pressing the silane coupling agent-coated surface of the inorganic substrate and the adhesive surface of the heat-resistant polymer film together while extruding the aqueous medium from between them; 1. A method for producing 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 following: [8] (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 of the inorganic substrate and / or the silane coupling agent-coated surface of the heat-resistant polymer film; (3) a step of stacking the inorganic substrate and the silane coupling agent-coated surface of the heat-resistant polymer film; (4) a step of pressing the adhesive surface of the inorganic substrate and the silane coupling agent-coated surface of the heat-resistant polymer film together while extruding the aqueous medium from between them; 1. A method for producing 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 following: [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 opposite to the adhesive surface with the inorganic substrate of the laminate obtained by the manufacturing process described in [7] or [8] above. [Effects of the Invention]

[0009] As explained in the section on the prior art, in laminates of heat-resistant polymer films for manufacturing flexible electronic devices and inorganic substrates, mainly glass plates, it is difficult to uniformly apply a silane coupling agent, especially over a large area, and as a result, it is difficult to uniformly and appropriately control the adhesive 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, and further, blister defects are less likely to occur between the heat-resistant polymer film and the inorganic substrate, and a large-area laminate can be realized that is rectangular and has an area of 0.65 square meters or more, with at least one side measuring 700 mm or more.Furthermore, by using this laminate, a method for manufacturing a large-area flexible electronic device can be provided.

[0010] Hereinafter, to avoid complication, the heat-resistant polymer film may be simply referred to as a polymer film or a film, and the inorganic substrate may be simply referred to as a substrate. Furthermore, the silane coupling agent simply refers to an amino group-containing silane coupling agent. The present invention is similar to the conventional technology in that a silane coupling agent is applied to either a polymer film or an inorganic substrate, and then the two are bonded (laminated). However, the present invention differs significantly in that an aqueous medium (e.g., pure water or a mixture of water and a water-soluble solvent such as a lower alcohol) is interposed between the two during lamination, and the aqueous medium is extruded outward from the adhesive surfaces during lamination. By this method, excess silane coupling agent between the inorganic substrate or polymer film can be removed, and the amount of silane coupling agent is controlled to the minimum amount necessary based on its affinity to the surface of at least one of the substrate and film. The adhesive strength between the substrate and the polymer film changes over time or after a high-temperature process, and is thought to be due to the reaction of excess, unreacted silane coupling agent progressing. However, the method of the present invention makes it possible to remove such excess unreacted material from the adhesive interface between the substrate and the film.

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

[0012] Furthermore, with this bonding method, excess silane coupling agent is eliminated, making it less likely that foreign matter will be generated by condensation of the silane coupling agent. At the same time, any debris or other matter that may be mixed in the adhesive surface is pushed out, dramatically reducing the amount of particle-sized foreign matter at the adhesive interface. As a result, the number of blister defects (also known as bubbles or floats) that are caused by these foreign matter is reduced.

[0013] According to the above-mentioned configuration, the silane coupling agent layer has a sufficient thickness to provide adhesive strength, and since there is no excess silane coupling agent, 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 speculate that in the initial stage of depositing the silane coupling agent on the inorganic substrate, there are many OH groups on the surface of the inorganic substrate, and these OH groups and the silane coupling agent layer are bonded by hydrogen bonding or chemical reaction, resulting in a strong silane coupling agent layer. However, if the silane coupling agent deposition time is extended, the silane coupling agent layer, which is not necessarily bonded strongly, is likely to penetrate into the heat-resistant polymer film, and the adhesive strength will vary depending on the type of bonding at the penetrated point.

[0014] In the above-mentioned configuration, it is preferable that the initial adhesive strength at 90° 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 90° initial adhesive strength is 0.06 N / cm or more, the heat-resistant polymer film can be suitably prevented from peeling off from the inorganic substrate before or during device formation.When the 90° initial adhesive strength is 0.25 N / cm or less, the device can be mechanically peeled off without breaking.

[0016] In the above-mentioned configuration, it is preferable that the density of blister defects 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-mentioned configuration, it is preferable that the number of bubbles between the heat-resistant polymer film and the inorganic substrate is one or less per 500 mm×500 mm.

[0019] If the number of bubbles is one or less per 500 mm×500 mm, the possibility of the device being destroyed due to bubble growth when the device is fabricated on the heat-resistant polymer film can be significantly reduced. [Brief explanation of the drawings]

[0020] [Figure 1] FIG. 1 is a schematic diagram of an apparatus for applying a silane coupling agent to an inorganic substrate. DETAILED DESCRIPTION OF THE INVENTION

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

[0022] Examples of the heat-resistant polymer film (hereinafter also simply referred to as polymer film) include films of polyimide resins such as polyimide, polyamideimide, polyetherimide, and fluorinated polyimide (e.g., aromatic polyimide resin, alicyclic polyimide resin); copolymer polyesters such as polyethylene, polypropylene, polyethylene terephthalate, polybutylene terephthalate, and polyethylene-2,6-naphthalate (e.g., wholly aromatic polyester, semi-aromatic polyester); copolymer (meth)acrylates typified by polymethyl methacrylate; polycarbonate; polyamide; polysulfone; polyethersulfone; polyetherketone; cellulose acetate; cellulose nitrate; aromatic polyamide; polyvinyl chloride; polyphenol; polyarylate; polyphenylene sulfide; polyphenylene oxide; polystyrene, etc. However, since the polymer films are intended to be used in processes involving heat treatment at 450° C. or higher, only a limited number of the exemplified polymer films can actually be applied. Among the polymer films, preferred are films made of so-called super engineering plastics, more specifically, aromatic polyimide films, aromatic amide films, aromatic amide-imide films, aromatic benzoxazole films, aromatic benzothiazole films, aromatic benzimidazole films, etc.

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

[0024] The polyamic acid (polyimide precursor) solution can be applied by any of the conventionally known solution application methods, such as spin coating, doctor blade, applicator, comma coater, screen printing, slit coating, reverse coating, dip coating, curtain coating, and slit die coating.

[0025] The diamines constituting the polyamic acid are not particularly limited, and aromatic diamines, aliphatic diamines, alicyclic diamines, etc., commonly used in polyimide synthesis, can be used. From the viewpoint of heat resistance, aromatic diamines are preferred, and among aromatic diamines, aromatic diamines having a benzoxazole structure are more preferred. The use of aromatic diamines having a benzoxazole structure makes it possible to achieve high heat resistance as well as a high elastic modulus, low thermal shrinkage, and a low coefficient of linear expansion. 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, and examples thereof include 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-aminobenzoxazolo)-4-(6-aminobenzoxazolo)benzene, 2,6-(4,4'-diazomethane)-1,1-dimethyl-2,2-dibenzoxazole, 1-(5-aminobenzoxazolo)-4-(6-aminobenzoxazolo)benzene ... 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-(3,4'-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, and the like.

[0027] Examples of aromatic diamines other than the above-mentioned aromatic diamines having a benzoxazole structure 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 aminodiphenyl 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'-diaminodi Phenylmethane, 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)phenyl]- bis(4-aminophenoxy)phenyl]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'-diaminodiphenyl sulfide, 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,Examples of such aromatic diamines include 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 aromatic diamine have been substituted with halogen atoms, alkyl or alkoxy groups having 1 to 3 carbon atoms, cyano groups, or halogenated alkyl or alkoxy groups having 1 to 3 carbon atoms in which some or all of the hydrogen atoms of the alkyl or alkoxy groups have been substituted with halogen atoms.

[0028] Examples of the aliphatic diamines include 1,2-diaminoethane, 1,4-diaminobutane, 1,5-diaminopentane, 1,6-diaminohexane, and 1,8-diaminoethane. Examples of the alicyclic diamines include 1,4-diaminocyclohexane and 4,4'-methylenebis(2,6-dimethylcyclohexylamine). 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 even more preferably 5% by mass or less. In other words, aromatic diamines preferably account for 80% by mass or more of all diamines, more preferably 90% by mass or more, and even more preferably 95% by mass or more.

[0029] Tetracarboxylic acids constituting polyamic acid can be aromatic tetracarboxylic acids (including their acid anhydrides), aliphatic tetracarboxylic acids (including their acid anhydrides), or alicyclic tetracarboxylic acids (including their acid anhydrides) commonly used in polyimide synthesis. Among these, aromatic tetracarboxylic acid anhydrides and alicyclic tetracarboxylic acid anhydrides are preferred, with aromatic tetracarboxylic acid anhydrides being more preferred from the viewpoint of heat resistance, and alicyclic tetracarboxylic acids being more preferred from the viewpoint of light transmittance. When these are acid anhydrides, they may contain one or two anhydride structures in the molecule, but preferably have two anhydride structures (dianhydrides). The tetracarboxylic acids may be used alone or in combination of two or more.

[0030] Examples of alicyclic tetracarboxylic acids include alicyclic tetracarboxylic acids such as cyclobutane tetracarboxylic acid, 1,2,4,5-cyclohexane tetracarboxylic acid, and 3,3',4,4'-bicyclohexyl tetracarboxylic acid, as well as their acid anhydrides. Among these, dianhydrides having two anhydride structures (e.g., cyclobutane tetracarboxylic dianhydride, 1,2,4,5-cyclohexane tetracarboxylic dianhydride, and 3,3',4,4'-bicyclohexyl tetracarboxylic dianhydride) are preferred. The alicyclic tetracarboxylic acids may be used alone or in combination of two or more. When transparency is important, the alicyclic tetracarboxylic acids preferably account for 80 mass % or more of the total tetracarboxylic acids, more preferably 90 mass % or more, and even more preferably 95 mass % or more.

[0031] The aromatic tetracarboxylic acid is not particularly limited, but is preferably a pyromellitic acid residue (i.e., one having a structure derived from pyromellitic acid), and more preferably an acid anhydride thereof. 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, and 2,2-bis[4-(3,4-dicarboxyphenoxy)phenyl]propanoic anhydride. When heat resistance is important, the aromatic tetracarboxylic acids preferably account for, for example, 80 mass % or more of all tetracarboxylic acids, more preferably 90 mass % or more, and even more preferably 95 mass % or more.

[0032] The thickness of the polymer film is preferably 3 μm or more, more preferably 11 μm or more, even more preferably 24 μm or more, and even more preferably 45 μm or more. There is no particular upper limit to the thickness of the polymer film, but for use as a flexible electronic device, it is preferably 250 μm or less, more preferably 150 μm or less, and even 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 even more preferably 1 ppm / °C to +10 ppm / °C. When the CTE is within this range, the difference in linear expansion coefficient with respect to a general support (inorganic substrate) can be kept small, and peeling between the polymer film and the inorganic substrate can be prevented even when the polymer film is subjected to a heat application process. Here, CTE is a factor that represents reversible expansion and contraction with temperature. The CTE of the polymer film refers to the average value of the CTE in the machine direction (MD) and the CTE in the width direction (TD) of the polymer film. The CTE of the polymer film is measured according to the method described in the Examples.

[0034] The heat shrinkage of the polymer film is preferably ±0.9%, more preferably ±0.6% between 30° C. and 500° C. The heat shrinkage is a factor that indicates irreversible expansion and contraction with respect to temperature.

[0035] The tensile breaking 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. There is no particular upper limit to the tensile breaking strength, but it is practically less than about 1000 MPa. If the tensile breaking strength is 60 MPa or more, it is possible to prevent the polymer film from breaking when peeling it from the inorganic substrate. The tensile breaking strength of the polymer film refers to the average value of the tensile breaking strength in the machine direction (MD) and the width direction (TD) of the polymer film. The tensile breaking strength of the polymer film is measured by the method described in the Examples.

[0036] The tensile breaking elongation of the polymer film is preferably 1% or more, more preferably 5% or more, and even more preferably 20% or more. When the tensile breaking elongation is 1% or more, the film has excellent handleability. The tensile breaking elongation of the polymer film refers to the average value of the tensile breaking elongation in the machine direction (MD) and the width direction (TD) of the polymer film. The tensile breaking elongation of the polymer film is measured by 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 polymer film undergoes little elongation deformation when peeled from the inorganic substrate, resulting in excellent handleability. 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 machine direction (MD) and the width direction (TD) of the polymer film. The tensile modulus of the polymer film is measured according to the method described in the Examples.

[0038] The thickness unevenness 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. If the thickness unevenness exceeds 20%, it tends to be difficult to apply to narrow areas. The thickness unevenness of the film can be calculated, for example, by measuring the film thickness at approximately 10 randomly selected positions on the film to be measured using a contact film thickness meter, and then using the following formula: Film thickness unevenness (%) = 100 x (maximum film thickness - minimum film thickness) ÷ average film thickness

[0039] The polymer film is preferably obtained in the form of a long polymer film wound up during production, having a width of 300 mm or more and a length of 10 m or more, and more preferably in the form of a rolled polymer film wound up on a winding core. When the polymer film is wound up in a roll, it can be easily transported in the form of a rolled heat-resistant polymer film.

[0040] The shape of the laminate can be various, including rectangular, circular, or square. Most heat-resistant polymer films are rectangular when they are made into rectangular laminates, and they can be applied to a variety of sizes, both small and large, depending on the intended use. Areas of 0.65 square meters or more are possible, and rectangles with sides of at least 700 mm are also possible. For large-area device fabrication, a more preferred area is 0.7 square meters or more, with 1 square meter or more being more preferred, and 5 square meters or less being easier to fabricate. The lower limit is not particularly limited, with 0.01 square meters or more being preferred, and 0.1 square meters or more being more preferred. The length of one side of the rectangle is more preferably 800 mm, and 900 mm or more being even more preferred. The lower limit is not particularly limited, but a preferred value is 50 mm or more, and a more preferred value is 100 mm or more.

[0041] In order to ensure the handling properties and productivity of the polymer film, it is preferable to add or contain approximately 0.03 to 3 mass % of a lubricant (particles) having a particle diameter of approximately 10 to 1000 nm to the polymer film, thereby imparting fine irregularities to the surface of the polymer film and ensuring slipperiness.

[0042] The inorganic substrate of the present invention may be any plate-shaped substrate that can be used as a substrate made of an inorganic material, and examples thereof include those that are primarily made of glass plates, ceramic plates, semiconductor wafers, metals, etc., and composites of these glass plates, ceramic plates, semiconductor wafers, and metals, such as laminates of these plates, composites in which these plates are dispersed, and composites in which fibers of these plates are contained. In the present invention, an inorganic substrate that does not contain nitrogen as a constituent element is preferably used.

[0043] Examples of the glass plate 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 / K or less are desirable, 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" and "OA11" manufactured by Nippon Electric Glass Co., Ltd., and "AF32" manufactured by SCHOTT are desirable.

[0044] The semiconductor wafer is not particularly limited, but examples include wafers of 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 these, the wafers that are preferably used are silicon wafers, and particularly preferred are mirror-polished silicon wafers having a size of 8 inches or more.

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

[0046] The planar portion of the inorganic substrate must be relatively flat. The surface roughness Ra of part or all of the surface of the inorganic substrate is preferably 1 nm or more, more preferably 3 nm or more, and is preferably 1000 nm or less, more preferably 600 nm or less, and even more preferably 100 nm or less. Within the above range, the inorganic substrate can be stably bonded to the polymer film. If the surface roughness is rougher than this, the adhesive 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 to the polymer film.

[0047] The thickness of the inorganic substrate is not particularly limited, but from the viewpoint of ease of handling, it is preferably 10 mm or less, more preferably 3 mm or less, and even more preferably 1.3 mm or less. The lower limit of the thickness is not particularly limited, 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 is physically or chemically present between the inorganic substrate and the metal-containing layer, and has the effect of bonding the inorganic substrate and the polymer film together. The silane coupling agent used in the present invention includes a coupling agent having at least an amino group. Specific preferred 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, and aminophenylaminomethylphenethyltrimethoxysilane.

[0049] Among the 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 an aromatic group connecting Si and the amino group. In addition to the above, 11-amino-1-undecenethiol can also be used as the coupling agent.

[0050] The silane coupling agent layer can be formed by applying a silane coupling agent solution to the inorganic substrate, by vapor deposition, etc. The silane coupling agent layer may also be formed on the surface of the heat-resistant polymer.

[0051] As a method for applying the silane coupling agent solution, a solution obtained by diluting the silane coupling agent with a solvent such as alcohol can be appropriately used by a conventionally known solution application method such as spin coating, curtain coating, dip coating, slit die coating, gravure coating, bar coating, comma coating, applicator method, screen printing, or spray coating.

[0052] The silane coupling agent layer can also be formed by vapor deposition. Specifically, the inorganic substrate is exposed to the vapor of the silane coupling agent, i.e., the silane coupling agent is substantially in a gaseous state. The vapor of the silane coupling agent can be obtained by heating the liquid silane coupling agent to a temperature between 40°C and 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 above 200°C is not recommended because it may cause side reactions on the organic groups of the silane coupling agent. The environment in which the silane coupling agent is heated may be under pressure, normal pressure, or reduced pressure, but normal pressure or reduced pressure is preferred to promote vaporization of the silane coupling agent. Since many silane coupling agents are flammable liquids, it is preferable to carry out the vaporization process in a sealed container, preferably after replacing the atmosphere in the container with an inert gas. The time for exposing the inorganic substrate to the silane coupling agent is not particularly limited, but is preferably within 20 hours, more preferably within 60 minutes, even more preferably within 15 minutes, and most preferably within 10 minutes. The temperature of the inorganic substrate during exposure to the silane coupling agent is preferably controlled to an appropriate temperature between −50° C. and 200° C. depending on the type of silane coupling agent and the desired thickness of the silane coupling agent layer.

[0053] The thickness of the silane coupling agent layer is extremely thin compared to inorganic substrates, polymer films, etc., and from a mechanical design perspective, the distance between the highest part of the inorganic substrate and the polymer film surface is negligible. In principle, a minimum thickness of a monolayer is sufficient. However, since it is necessary to fill the rough surface, a thicker film is required for practical application. In other words, a silane coupling agent equivalent to the volume of the roughened surface of the inorganic substrate is required. Because very thin layers exist on the rough surface, measuring the film thickness is often difficult. The film thickness of the silane coupling agent layer is generally less than 20 nm from the top of the inorganic substrate, preferably 15 nm or less, and more preferably 10 nm or less for practical use, more preferably 7 nm or less, and even more preferably 5 nm or less. However, if the silane coupling agent layer exists in clusters rather than as a uniform coating, the adhesion area with the polymer film is reduced, which is undesirable. The film thickness of the silane coupling agent layer can be calculated from the concentration of the silane coupling agent solution and the amount applied during application.

[0054] The laminate of the present invention comprises an inorganic substrate, an amino group-containing silane coupling agent layer, and a heat-resistant polymer film laminated in this order, and after peeling the heat-resistant polymer film from the inorganic substrate at a 90° angle, the nitrogen element ratio of the peeled surface of the inorganic substrate must exceed 3.5 atomic %. It is preferably 4 atomic % or more, and more preferably 5 atomic % or more. It is also 11 atomic % or less. It is preferably 9 atomic % or less, and more preferably 8 atomic % or less. When the nitrogen element ratio is within the above range, the adhesive strength between the heat-resistant polymer film and the inorganic substrate can be uniformly and appropriately controlled. It also prevents air bubbles from forming 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 even more preferably, it is 3 or less. There is no particular lower limit, but industrially, it may be 1 or more. Within the above range, a high-quality laminate can be obtained.

[0056] Such a laminate is [A method] (1) a step of applying a silane coupling agent containing an amino group to at least one surface of an inorganic substrate; (2) supplying an aqueous medium to the silane coupling agent-coated surface of the inorganic substrate and / or the adhesive surface of the heat-resistant polymer film; (3) a step of overlaying a heat-resistant polymer film on the silane coupling agent-coated surface of the inorganic substrate; (4) a step of pressing the silane coupling agent-coated surface of the inorganic substrate and the adhesive surface of the heat-resistant polymer film together while extruding the aqueous medium from between them; The above can be preferably obtained by a lamination method characterized by carrying out the above steps in this order. In addition, in the present invention, [B method] (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 of the inorganic substrate and / or the silane coupling agent-coated surface of the heat-resistant polymer film; (3) a step of stacking the inorganic substrate and the silane coupling agent-coated surface of the heat-resistant polymer film; (4) a step of pressing the adhesive surface of the inorganic substrate and the silane coupling agent-coated surface of the heat-resistant polymer film together while extruding the aqueous medium from between them; The above can be preferably obtained by a lamination method characterized by carrying out the above steps in this order.

[0057] The aqueous medium may be water or a mixture of water and a water-soluble solvent. Examples of the water-soluble solvent include lower alcohols, low-molecular-weight ketones, and tetrahydrofuran. Preferred aqueous media include pure water, a mixture of water and methanol, a mixture of water and ethanol, a mixture of water, isopropanol, and methyl ethyl ketone, and a mixture of water and tetrahydrofuran. The aqueous medium particularly preferably used in the present invention is water, a monohydric alcohol, a dihydric alcohol, or a trihydric alcohol that is liquid at room temperature, or a mixture containing two or more of these components. A trace amount of surfactant may be added to the aqueous medium to improve the wettability of the aqueous medium with the inorganic substrate or polymer film.

[0058] As a method for wetting the adhesive surface of the substrate or film with the aqueous medium, any of the existing methods can be applied, such as dropping using a dropper or dispenser, discharging from a valve, spraying in mist form from a spray nozzle, etc. Immersing the substrate or film in the aqueous medium is also an effective means for wetting. When a liquid containing water or alcohol is used as the aqueous medium, it also contributes to accelerating the reaction of the silane coupling agent.

[0059] The inorganic substrate and the heat-resistant polymer film can be bonded together by a pressing method, a roll lamination method, or the like. For example, pressure can be applied in a planar or linear manner by pressing, laminating, or roll laminating under atmospheric pressure or in a vacuum. The process can also be accelerated by applying heat during the application of pressure. In the present invention, pressing or roll laminating under atmospheric pressure is preferred, and a method using a roll (such as roll laminating) is particularly preferred because it allows bonding while gradually pushing out the aqueous medium at the adhesive interface from the adhesive surface.

[0060] The pressure applied during pressure application (pressure treatment) is preferably 0.1 MPa to 20 MPa, and more preferably 0.2 MPa to 3 MPa. If the pressure is 20 MPa or less, damage to the inorganic substrate can be suppressed. If the pressure is 0.1 MPa or more, the occurrence of areas where adhesion is not achieved or insufficient adhesion can be prevented. It is also preferable to apply heat during pressure treatment (pressure heat treatment). The temperature during pressure heat treatment 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. Although the pressure and heat treatment can be carried out in an atmospheric pressure environment as mentioned above, it may be possible to obtain a more uniform adhesive strength by carrying out the treatment in a vacuum. The degree of vacuum achieved by a normal oil rotary pump is sufficient, and a vacuum of about 10 Torr or less is sufficient. As for equipment that can be used for pressure and heat treatment, for example, the "11FD" manufactured by Imoto Manufacturing Co., Ltd. can be used for pressing in a vacuum, and for vacuum lamination using a roll-type film laminator in a vacuum or a film laminator that applies pressure to the entire surface of the glass at once using a thin rubber film after creating a vacuum, for example, the "MVLP" manufactured by Meiki Manufacturing Co., Ltd. can be used.

[0061] The pressure and heat treatment can be carried out in two separate steps: a pressure process and a heating process. In this case, the polymer film and the inorganic substrate are first pressed (preferably at about 0.2 to 50 MPa) at a relatively low temperature (for example, less than 120°C, more preferably at a temperature of 80 to 110°C) to ensure close contact between them, and then heated at a relatively high temperature (for example, 80°C or higher, more preferably 100 to 250°C, and even more preferably 120 to 220°C) under pressure (preferably 20 MPa or lower, 0.2 MPa or higher) or at normal pressure, thereby accelerating the chemical reaction at the contact interface and laminating the polymer film and the inorganic substrate.

[0062] In this manner, a laminate in which the inorganic substrate and the polymer film are bonded together can be obtained. However, the method for producing 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, so that the silane coupling agent layer comes into contact with water during lamination to form a desirable silane coupling agent layer, and then the inorganic substrate may be attached at almost the same time. Alternatively, the inorganic substrates may be bonded together by dropping pure water onto both the heat-resistant polymer film and the inorganic substrate to promote the reaction of the silane coupling agent and achieve the desired bonding state.

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

[0064] The laminate preferably has an adhesive strength (hereinafter also referred to as 90° initial adhesive strength) of 0.06 N / cm or more, more preferably 0.09 N / cm or more, and even more preferably 0.1 N / cm or more, measured by a 90° peeling method when peeling the heat-resistant polymer film from the laminate. The 90° initial adhesive strength is preferably 0.25 N / cm or less, more preferably 0.2 N / cm or less. An initial 90° adhesive strength of 0.06 N / cm or more can prevent the heat-resistant polymer film from peeling off from the inorganic substrate before or during device formation. An initial 90° adhesive strength of 0.25 N / cm or less can facilitate peeling of the inorganic substrate and the heat-resistant polymer film after device formation. That is, an initial 90° adhesive strength of 0.25 N / cm or less facilitates peeling of the inorganic substrate and the heat-resistant polymer film, even if the adhesive strength between them increases slightly during device formation. In this specification, the 90-degree initial adhesive strength refers to the adhesive strength at 90 degrees between the inorganic substrate and the heat-resistant polymer film after the laminate is heat-treated at 200° C. for 1 hour in an air atmosphere.

[0065] The conditions for measuring the 90-degree initial adhesive strength are as follows. The heat-resistant polymer film is peeled off from the inorganic substrate at a 90-degree angle. The measurement is carried out five times and the average value is used as the measurement value. Measurement temperature; room temperature (25℃) Peeling speed: 100mm / min atmosphere; atmosphere Measurement sample width: 2.5cm More specifically, according to the method described in the Examples.

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

[0067] In this specification, "adhesive strength" refers to both "initial adhesive strength" and "adhesive strength after heat treatment." In other words, "adhesive strength of 0.06 N / cm or more and 0.25 N / cm or less" means "initial adhesive strength of 0.06 N / cm or more and 0.25 N / cm or less" and "adhesive strength after heat treatment of 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 Method A or Method B opposite to the adhesive surface of the heat-resistant polymer film, and after formation, the heat-resistant polymer film is peeled off from the inorganic substrate together with the functional element, thereby producing a flexible electronic device.

[0069] In this specification, the term "electronic device" refers to a wiring substrate having a single-sided, double-sided, or multi-layer structure that carries electrical wiring, an electronic circuit including active elements such as transistors and diodes, and passive devices such as resistors, capacitors, and inductors, as well as sensor elements that sense pressure, temperature, light, humidity, etc., biosensor elements, light-emitting elements, image display elements such as liquid crystal displays, electrophoretic displays, and self-luminous displays, wireless and wired communication elements, computing elements, memory elements, MEMS elements, solar cells, thin-film transistors, etc.

[0070] In the method for producing a flexible electronic device herein, an electronic device is formed on the polymer film surface of the laminate produced by the above-described method, and then the polymer film is peeled off from the inorganic substrate.

[0071] The method for peeling a polymer film on which an electronic device has been formed from an inorganic substrate is not particularly limited, but may include peeling from the edge using tweezers, making an incision in the polymer film, attaching adhesive tape to one side of the incision, and then peeling from the tape, or vacuum-adhering one side of the incision in the polymer film and then peeling from that part. Note that if a small curvature occurs at the incision during peeling, stress will be applied to the device in that area, potentially destroying the device. Therefore, peeling with as large a curvature as possible is desirable. For example, it is desirable to peel the film while winding it around a roll with a large curvature, or to use a machine configured so that a roll with a large curvature is positioned at the peeling area. Methods for making incisions in the polymer film include, but are not limited to, a method of cutting the polymer film with a cutting tool such as a blade, a method of cutting the polymer film by scanning a laser relative to the laminate, a method of cutting the polymer film by scanning a water jet relative to the laminate, and a method of cutting the polymer film while cutting slightly into the glass layer using a semiconductor chip dicing device. For example, when employing the above-mentioned methods, it is also possible to appropriately employ techniques such as superimposing ultrasonic waves on the cutting tool or adding reciprocating or up-and-down motion to improve cutting performance. Another useful method is to attach another reinforcing substrate to the area to be peeled and peel off the reinforcing substrate together. When the flexible electronic device to be peeled off is a backplane of a display device, it is also possible to attach a frontplane of the display device to the inorganic substrate in advance, integrate the two together on the inorganic substrate, and then peel off the two at the same time to obtain a flexible display device. [Example]

[0072] The present invention will be described in detail below using examples, but the present invention is not limited to the following examples as long as it does not depart from the gist of the invention.

[0073] Unless otherwise specified, the measurements in the examples and comparative examples were measured by the following methods.

[0074] <Thickness of heat-resistant polymer film> Measurement was carried out using a micrometer (Militron 1245D, manufactured by Fineruf Co., Ltd.).

[0075] <Tensile modulus, tensile strength at break, and tensile elongation at break of heat-resistant polymer film> Test specimens were prepared by cutting the polymer film into strips measuring 100 mm x 10 mm in both the machine direction (MD) and the width direction (TD). Test specimens were cut from the center of the width direction. Using a tensile tester (Shimadzu Corporation, Autograph®, model AG-5000A), the tensile modulus, tensile strength at break, and tensile elongation at break were measured in both the MD and TD directions at a temperature of 25°C, a tensile speed of 50 mm / min, and a chuck distance of 40 mm.

[0076] <Coefficient of Linear Expansion (CTE)> The stretch rate was measured in the machine direction (MD) and width direction (TD) of the polymer film under the following conditions. The stretch rate / temperature was measured at intervals of 15°C, such as 30°C to 45°C and 45°C to 60°C. This measurement was continued up to 300°C, and the average value of all the measured values was calculated as the 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

[0077] <Measurement of adhesive strength> The adhesive strength of the polymer film was measured by the 90-degree peeling method from the laminate obtained by the production of the laminate, as follows. The film is peeled off at a 90 degree angle from the inorganic substrate. Measuring device: Shimadzu Autograph AG-IS Measurement temperature; room temperature (25℃) Peeling speed: 100mm / min atmosphere; atmosphere Measurement sample width: 2.5cm The measurements were taken at five points in total, including the center of the laminate and each of the four corners, and the average value was calculated.

[0078] <Counting blister defects> In the present invention, blisters with a major axis of 300 μm or more were counted. Blisters are also called floating defects or air bubble defects, and are areas where the film is not adhered to the substrate and rises up like a bubble. They often occur when a relatively hard foreign object pinches the film, lifting it up like a tent. In the present invention, the laminate is observed under magnification with the focus on the adhesive surface between the inorganic substrate and the polymer film, and the number of blisters with a major axis of 300 μm or more is counted at least For G2 (370mm x 470mm) size laminates, 4 sheets For G4.5 (730mm x 920mm) size laminates, two sheets One sheet for G5 (1100mm x 1250mm) size laminate The number was counted and converted to the number per square meter.

[0079] <Nitrogen element composition ratio> The polymer film was peeled off from the laminate at a 90° angle, and the peeled surface (50mm x 50mm) was analyzed by ESCA to evaluate the proportion of nitrogen element present on the peeled surface of the inorganic substrate. + (manufactured by Thermo Fisher Scientific) was used. The measurement conditions are as follows. During the analysis, background was removed by the Shirley method. The surface composition ratio was calculated as the average value of the measurement results at three or more locations. Measurement conditions Excitation X-ray: Monochromated Al Kα ray X-ray output: 12kV, 6mA Photoelectron escape angle: 90° Spot size: 400 μmφ Pass energy: 50 eV Step: 0.1 eV

[0080] <Surface roughness Ra of inorganic substrate> The Ra was measured using a confocal microscope (HYBRID C3 manufactured by Lasertec). Measurements were performed using a 50x objective lens, a scan resolution of 0.06 μm, and the color channel in Blue mode. The measurement (observation) range was a square area of approximately 300 μm in both X and Y. For the SUS substrate, the edges were kept out of the measurement range, but after confirming that the Ra value did not change with any further positional dependency, the measurement was carried out without determining a specific position.

[0081] [Preparation of Polyamic Acid Solution A] After replacing the atmosphere in a reaction vessel equipped with a nitrogen inlet tube, thermometer, and stirrer with nitrogen, 223 parts by weight of 5-amino-2-(p-aminophenyl)benzoxazole (DAMBO) and 4416 parts by weight of N,N-dimethylacetamide were added to the reaction vessel and completely dissolved. Next, 217 parts by weight of pyromellitic dianhydride (PMDA) and Snowtex (DMAC-ST30, manufactured by Nissan Chemical Industries, Ltd.), a dispersion of colloidal silica (average particle size: 0.08 μm) in dimethylacetamide, were added so that the colloidal silica accounted for 0.7% by weight of the total polymer solids in polyamic acid solution A. The mixture was stirred at 25°C for 24 hours to obtain a brown, viscous polyamic acid solution A.

[0082] [Polyimide film preparation example 1] Polyamic acid solution A was applied to a mirror-finished endless continuous stainless steel belt (coating width: 1240 mm) using a die coater and dried for 10 minutes at 90 to 115° C. After drying, the polyamic acid film became self-supporting and was peeled off from the support, and both ends were cut to obtain a green film. The resulting green film was conveyed using a pin tenter so that the final pin sheet spacing was 1140 mm, and subjected to heat treatment 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 promote the imidization reaction. The film was then cooled to room temperature over 2 minutes, and the poorly flat portions at both ends of the film were cut off with a slitter. The film was then wound up into a roll to obtain Polyimide Film 1 shown in Table 1.

[0083] [Polyimide film preparation example 2] The same procedure was repeated except that the gap of the die coater was changed so that the final polyimide film thickness would be 38 μm, to obtain Polyimide Film 2 shown in Table 1.

[0084] [Polyimide film 3] A 25 μm thick polyimide film, Upilex25S (registered trademark) manufactured by Ube Industries, was used as the polyimide film 3 .

[0085] <Preparation of laminate> Example 1 First, the polyimide film 1 obtained in Preparation Example 1 was cut into a width of 370 mm x 500 mm. Next, the film surface was treated by irradiating it with UV / O3 for 3 minutes using a UV / O3 irradiator (SKR1102N-03 manufactured by LAN Technical). The distance between the UV / O3 lamp and the film was 30 mm.

[0086] Using the apparatus shown in the schematic diagram of Figure 1, an amino group-containing silane coupling agent was applied via vapor phase to a G2 size inorganic substrate (a SUS substrate measuring 370 mm x 470 mm and 0.7 mm thick). The inorganic substrates used were washed with pure water, dried, and then irradiated with a UV / O3 irradiator (SKR1102N-03 manufactured by LAN Technical) for 1 minute to dry clean. The inorganic substrate was placed in the chamber of the device, and 130 g of 3-aminopropyltrimethoxysilane (KBM-903, manufactured by Shin-Etsu Chemical Co., Ltd.) was placed in a 1 L chemical tank. The outer water bath was heated to 42°C, and the resulting silane coupling agent vapor was sent into the chamber along with clean, dry air at a gas flow rate of 22 L / min, exposing the inorganic substrate to the silane coupling agent vapor. The substrate temperature was 21°C, the clean, dry air temperature was 23°C, and the humidity was 1.2% RH. The exhaust was connected to a negative-pressure exhaust port, and a differential pressure gauge confirmed that the chamber was at a negative pressure of approximately 10 Pa.

[0087] The inorganic substrate coated with the amino group-containing silane coupling agent in this manner was set in a roll laminator equipped with a silicone rubber roller, and first, 100 ml of pure water was dropped using a dropper onto the silane coupling agent-coated surface so that it spread over the entire substrate, wetting the substrate.

[0088] Next, the surface-treated side of the polyimide film was placed facing the silane coupling agent-coated side of the inorganic substrate, i.e., the side wetted with pure water, and the inorganic substrate and polyimide film were laminated by sequentially pressing the rotating roll from one side of the inorganic substrate while squeezing out the pure water between the polyimide film and the inorganic substrate to obtain a temporary laminate. The laminator used was a laminator manufactured by MCK Corporation with an effective roll width of 1350 mm, and the lamination conditions were: air source pressure: 0.5 MPa, lamination speed: 50 mm / sec, roll temperature: 22 ° C, ambient temperature: 22 ° C, humidity: 55% RH. The resulting temporary laminate was heat-treated in a clean oven at 200° C. for 10 minutes to obtain a laminate of the present invention. The same operation was carried out on four inorganic substrates. The evaluation results of the obtained laminate are shown in Table 2.

[0089] (Examples 2 to 20, Comparative Examples 1 to 4) Similarly, laminates were prepared under the conditions shown in Tables 2 to 5, 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 are as follows. Note 1 in the tables indicates that the film and inorganic substrate did not adhere to each other, so the peel surface could not be defined and the nitrogen element component ratio could not be measured. Film 1: Polyimide film obtained in Polyimide Film Preparation Example 1 Film 2: Polyimide film obtained in Polyimide Film Preparation Example 2 Film 3: Polyimide film Upilex25S (registered trademark) manufactured by Ube Industries, Ltd. Glass: Nippon Electric Glass OA10G The sizes of the inorganic substrates are as follows: 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), all of which are the same size. G2 size (370mm x 470mm) G4.5 size (730mm x 920mm) G5 size (1100mm x 1250mm) aqueous medium Pure water: ultra pure water Pure water + MeOH: Pure water 99 / methanol 1 (mass ratio) Pure water + EtOH: Pure water 99 / ethanol 1 (mass ratio) 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 (75 nm thick) was formed on a polyimide film by vacuum deposition, and then a silicon oxide film (150 nm thick) was laminated on the polyimide film without exposure to the atmosphere. Next, a silicon oxynitride film (100 nm thick) was formed as a base insulating film by plasma CVD, and then an amorphous silicon film (54 nm thick) was laminated on the polyimide film without exposure to the atmosphere.

[0096] Next, the amorphous silicon film was subjected to a heat treatment at 500° C. for 40 minutes to remove hydrogen elements from the film and promote crystallization, thereby forming a polysilicon film. The resulting polysilicon film was used to fabricate TFT elements. First, the polysilicon thin film was patterned to form silicon regions of the desired shape, followed by the formation of a gate insulating film, a gate electrode, the formation of source and drain regions by doping into the active region, the formation of an interlayer insulating film, the formation of source and drain electrodes, and an activation process, to fabricate an array of P-channel TFTs using polysilicon. The polymer film was burned off with a UV-YAG laser along a distance of approximately 0.5 mm inside the outer periphery of the TFT array, and then peeled off from the edge of the cut using a thin razor blade, yielding a flexible A3-sized TFT array. The peeling angle was 3 degrees. Peeling was possible with minimal force, and it was possible to peel off the TFTs without damaging them. The resulting flexible TFT array maintained its good characteristics even when wrapped around a 3 mm diameter rod, with no noticeable deterioration in performance. [Industrial Applicability]

[0097] As described above, the laminate manufacturing method of the present invention and the laminate obtained therefrom can achieve stable, uniform low adhesive strength even in large areas, and the occurrence of blister defects is extremely low. Therefore, they are extremely useful as temporary support substrates for manufacturing high-quality, large-area flexible devices. [Explanation of symbols]

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

Claims

1. A laminate having, in this order, an inorganic substrate, a silane coupling agent layer containing an amino group, and a heat-resistant polymer film, wherein after the heat-resistant polymer film is peeled off at a 90° angle from the inorganic substrate, the nitrogen element ratio on the peeled surface on the inorganic substrate side is more than 3.5 atomic % and 11 atomic % or less; A laminate characterized in that the density of blister defects is 12 or less per square meter.

2. 2. The laminate according to claim 1, wherein the adhesive strength when peeling the heat-resistant polymer film from the laminate by a 90° peeling method is 0.06 N / cm or more and 0.25 N / cm or less.

3. 2. The laminate according to claim 1, wherein the inorganic substrate has a surface roughness Ra of 1 nm or more and 1000 nm or less.

4. 2. The laminate according to claim 1, wherein the heat-resistant polymer film is a polyimide film.

5. 5. The laminate according to claim 1, wherein the laminate is rectangular, has an area of 0.65 square meters or more, and one side of the rectangle is at least 700 mm or more.

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