Polyimide film

Abstract

To provide a polyimide film useful for metal lamination and related purposes.SOLUTION: A polyimide film comprises, on one side or both sides thereof, a layer (A) comprising a hydrolytic condensation product of a coupling agent.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to polyimide films and the like.

Background Art

[0002] Polyimide films are widely used as electrical insulation materials for electric wires, base films for chip-on-film (COF), flexible printed wiring boards (FPC), carrier tape films for tape automated bonding (TAB) of ICs, and tapes for fixing lead frames of ICs, etc., due to their excellent heat resistance, chemical resistance, and electrical properties.

[0003] With the miniaturization, weight reduction, high functionality, multi-functionality, and high-density mounting of electronic devices, the printed wiring boards used in these electronic devices are rapidly becoming more highly dense due to the narrowing of conductor widths and conductor intervals, multi-layerization, flexibility, and thinning of the substrate.

[0004] Conventionally, a three-layer flexible printed wiring substrate in which a conductor layer (a metal layer such as a copper layer) is bonded to a polyimide film via an adhesive layer has been known (Patent Document 1).

[0005] On the other hand, when a polyimide film is bonded to a conductor layer via an adhesive layer, sufficient adhesiveness (adhesion) may not be obtained between the polyimide film and the metal layer. Under such circumstances, when manufacturing a polyimide film, a solution containing a heat-resistant surface treatment agent is applied to the surface of a solidified film (self-supporting film) of polyamic acid, and the solidified film is heat-treated to imidize it, thereby obtaining a polyimide film with improved adhesion (Patent Document 2).

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

[0007] The object of the present invention is to provide a polyimide film suitable for use in metal lamination (for lamination of metal layers), etc. [Means for solving the problem]

[0008] As described above, it is known that polyimide films can be produced by applying a surface treatment agent to the surface of a self-supporting polyamic acid film and then heat-treating it.

[0009] However, the inventors have found that while the adhesion between the polyimide film and the metal layer is improved immediately after lamination of the metal layer in the polyimide film obtained in this manner, this adhesion may tend to decrease when the metal layer laminated film is exposed to high temperatures.

[0010] Therefore, the inventors investigated polyimide films for metal lamination from a perspective completely different from that of conventional polyimide films. Surprisingly, the inventors then considered applying the surface treatment agent not to the self-supporting polyamic acid film, but to the polyimide film after imidization. However, when applying a surface treatment agent to a polyimide film after imidization, unlike when applying it to a self-supporting polyamic acid film, it was difficult to form a layer containing hydrolysis condensates of the surface treatment agent on the polyimide film, possibly because the polyimide and the surface treatment agent did not react much (i.e., not many chemical bonds were formed between the polyimide and the surface treatment agent). Furthermore, depending on the type of surface treatment agent, it was difficult to efficiently form such a layer, and forming a layer containing hydrolysis condensates of the surface treatment agent on the polyimide film after imidization proved extremely challenging.

[0011] In this context, the inventors, after further intensive research, have discovered that a polyimide film having a layer containing a hydrolysis condensate of a surface treatment agent can be efficiently obtained by treating a specific surface treatment agent (particularly a coupling agent such as a silane coupling agent) under specific conditions [for example, the concentration of the coupling agent in the coupling agent-containing solution, and the drying conditions after coating the coupling agent (for example, drying temperature, drying time, etc.)]. The inventors have found that such a polyimide film is suitable for laminating a metal layer, that sufficient adhesion can be achieved without providing an adhesive layer (in particular, even thin metal layers can be laminated with sufficient adhesion), and that the metal layer laminated polyimide film, in which a metal layer is laminated onto the film, can suppress the decrease in the above-mentioned adhesion even when exposed to high-temperature conditions. Furthermore, the inventors discovered that when the film is a metal-layered polyimide film in which a metal layer is laminated, the decrease in adhesion when exposed to high-temperature conditions can be suppressed more effectively than when a polyimide film obtained by applying a surface treatment agent to a self-supporting polyamic acid film is used. Further research led to the completion of the present invention.

[0012] In other words, the present invention relates to the following inventions, etc. [1] A polyimide film (particularly a polyimide film for metal lamination) having a layer (A) on one or both sides containing (or formed from) a hydrolysis condensate of a coupling agent (e.g., a silane coupling agent). [2] A polyimide film (particularly a polyimide film for metal lamination) in which, when a copper layer (for example, a copper layer with a thickness of 8.5 μm, or a copper layer with a thickness of 8.5 μm via a metal layer (copper layer) formed by sputtering) is directly laminated, the peel strength between the copper layer and the polyimide film (e.g., 90° peel strength) is T1, and the peel strength between the copper layer and the polyimide film after heating at 150°C for 168 hours (e.g., 90° peel strength) is T2, wherein T1 is 0.4 kN / m or greater, and T2 / T1 is 0.7 or greater. Such polyimide films may also be manufactured, for example, by applying a coupling agent-containing solution to one or both sides of an (imidized) polyimide film and drying it (hydrolysis condensation), as described later. In other words, such polyimide films may be polyimide films obtained by applying a coupling agent-containing solution to one or both sides of an (imidized) polyimide film and drying it (hydrolysis condensation). [3] The polyimide film according to [1], wherein the coupling agent has an amino group. [4] A polyimide film according to [1] or [3], wherein the coupling agent comprises a silane coupling agent. [5] A polyimide film according to any one of [1] and [3] to [4], wherein the coupling agent comprises an amino-based silane coupling agent. [6] A polyimide film according to any of [1] and [3] to [5], wherein the thickness of layer (A) is 100 to 400 nm. [7] A polyimide film according to any one of [1] and [3] to [6], wherein layer (A) comprises a layer (or film) (1) of a hydrolysis condensate of a coupling agent (on the surface side). [8] A polyimide film according to any one of [1] and [3] to [7], comprising layer (A) and layer (2) containing a hydrolysis condensate of a coupling agent and a component derived from polyimide. [9] The polyimide film according to [8], wherein the thickness of layer (2) is 300 nm or less.

[10] A polyimide film according to any one of [1] and [3] to [9], comprising 3-aminopropyltrimethoxysilane as a coupling agent.

[11] When the linear expansion coefficient in the machine conveyance direction (MD) of the film is αMD and the linear expansion coefficient in the width direction (TD) is αTD, the value of (|αMD| + |αTD|) / 2 is 15 ppm / K or less, and the polyimide film described in any one of [1] to

[10] .

[12] αTD is -5 to +10 ppm / K, and the polyimide film described in any one of [1] to

[11] .

[13] (The polyimide constituting the polyimide film) is a polymerization component of an aromatic diamine component containing at least one selected from paraphenylenediamine and 4,4'-diaminodiphenyl ether, and an aromatic acid anhydride component containing at least one selected from pyromellitic dianhydride and 3,3',4,4'-biphenyltetracarboxylic dianhydride, and the polyimide film described in any one of [1] to

[12] .

[14] Containing inorganic particles, and the polyimide film described in any one of [1] to

[13] .

[15] In a roll shape, and the polyimide film described in any one of [1] to

[14] .

[16] Containing inorganic particles at a ratio of 0.01 to 5% by mass and in a roll shape with a length of 5 m or more, and the polyimide film described in any one of [1] to

[15] .

[17] For metallizing (such as for plating), and the polyimide film described in any one of [1] to

[16] .

[18] For directly laminating a metal layer (or without an adhesive layer in between) (for example, directly laminating a copper layer with a thickness of 20 μm or less), and the polyimide film described in any one of [1] to

[17] .

[19] A laminated film composed of a polyimide film and a metal layer directly laminated on this film (or without an adhesive layer in between), and the polyimide film is the polyimide film described in any one of [1] to

[18] .

[20] The laminated film according to

[19] , wherein the metal layer is a copper layer with a thickness of 20 μm or less. [twenty one] The laminated film according to

[19] or

[20] , wherein the peel strength (e.g., 90° peel strength) T1 between the metal layer and the polyimide film is 0.5 kN / m or more. [twenty two] A laminated film according to any one of

[19] to

[21] , wherein T1 is the peel strength between the metal layer and the polyimide film (e.g., 90° peel strength), and T2 is the peel strength between the metal layer and the polyimide film after heating at 150°C for 168 hours (e.g., 90° peel strength), and T1 is 0.4 kN / m or more, and T2 / T1 is 0.7 or more. [twenty three] A method for producing a polyimide film (particularly a polyimide film for metal lamination, or a polyimide film according to any one of [1] to

[18] ), comprising the step of applying a solution containing a coupling agent (e.g., a silane coupling agent) to one or both sides of the polyimide film, and then drying it. [twenty four] The manufacturing method according to

[23] , wherein the coupling agent (e.g., silane coupling agent) containing solution contains 0.1 to 5% by mass of the coupling agent (e.g., silane coupling agent). [twenty five] The manufacturing method according to

[23] or

[24] , wherein drying is performed at a drying temperature of 130 to 200°C and a drying time of 40 to 100 seconds. [Effects of the Invention]

[0013] The present invention provides a polyimide film. Such a polyimide film is suitable for metal lamination (for metal layer lamination, for metal layer formation, etc.).

[0014] For example, in one embodiment of polyimide film, a metal layer (e.g., a copper layer) can be laminated (formed) with sufficient adhesion. Since such adhesion can be ensured without providing an adhesive layer (even by directly forming the metal layer), the metal layer can also be suitably formed by metallizing [or a metallizing method or metallizing treatment, for example, a plating method (wet or dry plating method, for example, vacuum deposition, sputtering, or ion plating)].

[0015] Therefore, with such polyimide films, sufficient adhesion can be achieved even with thin metal layers (for example, with thicknesses of 30 μm or less, 20 μm or less, 10 μm or less, etc.).

[0016] In another embodiment of the polyimide film of the present invention, the above-mentioned sufficient adhesion can be efficiently maintained even when exposed to conditions such as high temperatures.

[0017] In another embodiment of the polyimide film of the present invention, it is possible to achieve sufficient adhesion to the metal layer while possessing useful or effective functions as a base film (substrate film) {for example, heat resistance, dimensional stability (for example, dimensional stability during metal layer formation, dimensional stability after metal layer formation (for example, during processing))}.

[0018] In another embodiment of the polyimide film of the present invention, a high dielectric breakdown voltage can be achieved. Therefore, such polyimide films can provide high insulation properties. [Modes for carrying out the invention]

[0019] [Polyimide film] The polyimide film of the present invention may have a layer (A) on its surface that contains (or is formed from) a hydrolysis condensate of a coupling agent (hereinafter sometimes simply referred to as "layer (A)"). Layer (A) may also be a layer containing an element corresponding to the coupling agent [for example, silicon (corresponding to the silane coupling agent)]. Layer (A) may be formed on one side (or one side) of the polyimide film, or on both sides (or both sides). Such polyimide films can be formed, for example, by applying a coupling agent-containing solution to one or both sides of an (imidized) polyimide film and drying it (causing hydrolysis condensation).

[0020] (Layer(A)) The coupling agent may, for example, have a hydrolyzable (condensable) group (e.g., an alkoxy group, a halogen atom, etc.) and a reactive functional group [e.g., an amino group, an epoxy group, a mercapto group, a (meth)acryloyl group, a vinyl group, etc.].

[0021] Examples of coupling agents include silane coupling agents, titanium coupling agents, and aluminum coupling agents, and preferably, silane coupling agents. Coupling agents may be used individually or in combination of two or more types.

[0022] Examples of silane coupling agents include those having a silyl group to which a hydrolyzable (condensable) group (e.g., an alkoxy group, a halogen atom, etc.) is bonded. In silane coupling agents, the number of silicon atoms may be one or more, or two or more (for example, oligomer or polymer-type silane coupling agents).

[0023] Specific silane coupling agents are not particularly limited, but examples include amino-based silane coupling agents (silane coupling agents containing amino groups), epoxy-based silane coupling agents (silane coupling agents containing epoxy groups), mercapto-based silane coupling agents (silane coupling agents containing mercapto groups), (meth)acryloxy-based silane coupling agents (silane coupling agents containing (meth)acryloxy groups), vinyl-based silane coupling agents (silane coupling agents containing vinyl groups), and preferably amino-based silane coupling agents. One or more types of silane coupling agents may be used.

[0024] Examples of amino-based silane coupling agents include alkoxysilanes having an amino group [for example, aminoalkylalkoxysilanes (e.g., aminoalkyl mono to trialkoxysilanes such as 3-aminopropyltrimethoxysilane and 3-aminopropyltriethoxysilane, preferably aminoC1-4 alkyl mono to triC1-4 alkoxysilanes), (aminoalkylamino)alkylalkoxysilanes (e.g., (aminoalkylamino)alkyl mono to trialkoxysilanes such as 3-(2-aminoethylamino)propyltrimethoxysilane, 3-(2-aminoethylamino)propylmethyldimethoxysilane, and 3-(2-aminoethylamino)propyltriethoxysilane, preferably (aminoC1-4 amino)C1-4 alkyl mono to triC1-4 alkoxysilanes), phenylaminoalkylalkoxysilanes (e.g., phenylaminoalkyl mono to trialkoxysilanes such as N-phenyl-3-aminopropyltrimethoxysilane, preferably phenylaminoC1-4 alkyl mono to triC1-4 alkoxysilanes), etc.].

[0025] Examples of epoxy-based silane coupling agents include alkoxysilanes having epoxy groups [for example, glycidoxyalkylalkoxysilanes (e.g., glycidoxyalkyl mono to trialkoxysilanes such as 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropyltriethoxysilane, preferably glycidoxy C1-4 alkyl mono to triC1-4 alkoxysilanes), epoxycycloalkylalkoxysilanes (e.g., epoxycycloalkyl mono to trialkoxysilanes such as 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltriethoxysilane, preferably epoxy C3-10 cycloalkyl mono to triC1-4 alkoxysilanes), etc.].

[0026] Examples of mercapto-silane coupling agents include alkoxysilanes having a mercapto group [for example, mercaptoalkylalkoxysilanes (e.g., mercaptoalkyl mono to trialkoxysilanes such as 3-mercaptopropylmethyldimethoxysilane and 3-mercaptopropyltrimethoxysilane, preferably mercapto C1-4 alkyl mono to tri C1-4 alkoxysilanes)].

[0027] Examples of (meth)acryloxy silane coupling agents include alkoxysilanes having a (meth)acryloyl group [for example, (meth)acryloxyalkyl mono to trialkoxysilanes such as 3-(meth)acryloxypropyltrimethoxysilane, 3-(meth)acryloxypropyltriethoxysilane, 3-(meth)acryloxypropylmethyldimethoxysilane, 3-(meth)acryloxypropylmethyldiethoxysilane, preferably (meth)acryloxy C2-4 alkyl mono to triC1-4 alkoxysilanes, etc.].

[0028] Examples of vinyl-based silane coupling agents include vinyl group-containing silanes {e.g., halosilanes having a vinyl group (e.g., vinyl mono to trihalosilanes such as vinyltrichlorosilane), alkoxysilanes having a vinyl group [e.g., vinyl alkoxysilanes (e.g., vinyl mono to trialkoxysilanes such as vinyltrimethoxysilane and vinyltriethoxysilane, preferably vinyl mono to triC1-4 alkoxysilanes), vinyl alkoxyalkoxysilanes (e.g., vinyl tri(methoxyethoxy)silane, vinyltris(β-methoxyethoxy)silane, etc., vinyl mono to tri(C1-4 alkoxyC1-4 alkoxy)silanes), styryl group-containing silanes (e.g., styryl mono to trialkoxysilanes such as p-styryltrimethoxysilane, preferably styryl mono to triC1-4 alkoxysilanes), etc.]}.

[0029] Examples of titanium coupling agents include isostearoyl titanates (e.g., mono- or triisostearoyl titanates such as isopropyltriisostearoyl titanate, isopropyldimethacryloylisostearoyl titanate, isopropylisostearoyldiacrylic titanate, etc.), amino group-containing titanates (e.g., isopropyltri(N-aminoethyl-aminoethyl) titanate), isopropyltridecylbenzenesulfonyl titanate, isopropyl Examples include pyrtris(dioctyl pyrophosphate) titanate, tetraisopropylbis(dioctyl phosphite) titanate, tetra(2,2-diallyloxymethyl-1-butyl)bis(di-tridecyl) phosphite titanate, bis(dioctyl pyrophosphate) oxyacetate titanate, bis(dioctyl pyrophosphate) ethylene titanate, isopropyltrioctanoyl titanate, and isopropyltricumylphenyl titanate.

[0030] Examples of aluminum coupling agents include alkylacetacetate aluminum diisopropylate.

[0031] From the viewpoint of adhesion between the polyimide film and the metal layer of the present invention (particularly adhesion when exposed to high-temperature conditions), the coupling agent may preferably be one having an amino group (for example, an amino-based silane coupling agent). When using a coupling agent containing amino groups, although not certain, it is thought that the reaction between the polyimide film to which the coupling agent is applied and the coupling agent can be suppressed to some extent, and therefore amino groups remain on the surface of the polyimide film of the present invention [for example, the surface of layer (A)]. In other words, when using a coupling agent containing amino groups, it is thought that the surface of the polyimide film of the present invention contains amino groups. Furthermore, although not certain, it is thought that when a metal layer is laminated on such a polyimide film of the present invention, coordination bonds are formed between the amino groups and metal atoms (for example, copper atoms, etc.), which makes it easier to stabilize the metal layer, and thus easier to obtain good adhesion between the metal layer and the polyimide film of the present invention even when exposed to high-temperature conditions.

[0032] Layer (A) may also contain hydrolysis condensates of surface treatment agents other than coupling agents {for example, silane compounds [for example, mono- to tetraalkoxysilanes such as tetramethoxysilane and tetraethoxysilane, preferably mono- to tetraC1-4 alkoxysilanes], etc.}.

[0033] Layer (A) may have a layer (or film) (1) of hydrolysis condensate of the coupling agent. Layer (1) may be formed on the surface side of layer (A). Layer (1) may be formed substantially solely from hydrolyzed condensates of coupling agents and may not contain polyimide (or polyimide-derived components). Furthermore, if the polyimide film of the present invention has layers (A) on both sides (or both sides), layer (1) may be formed on both sides (or both sides) of the polyimide film, or on one side (or one side).

[0034] Layer (A) may have a layer (2) containing a hydrolysis condensate of a coupling agent and a component derived from polyimide. Layer (2) may be formed on the polyimide film side of layer (A). If layer (A) has layers (1) and (2), the layers may be formed in the order of layer (2) and layer (1) from the polyimide film (surface) side. Furthermore, if the polyimide film of the present invention has layer (A) on both sides (or both sides), layer (2) may be formed on both sides (or both sides) of the polyimide film, or on one side (or one side).

[0035] The thickness of layer (A) is not particularly limited, but from the viewpoint of adhesion between the polyimide film and the metal layer of the present invention, it may be, for example, 50 nm or more (e.g., 60 nm or more, 70 nm or more, 80 nm or more, 90 nm or more), preferably 100 nm or more (e.g., 110 nm or more, 120 nm or more, 130 nm or more, 140 nm or more, 150 nm or more, 160 nm or more, 170 nm or more, 180 nm or more, 190 nm or more, 200 nm or more).

[0036] The thickness (upper limit) of layer (A) is not particularly limited, but may be, for example, 500 nm or less (e.g., 480 nm or less, 450 nm or less, 430 nm or less), preferably 400 nm or less (e.g., 390 nm or less, 380 nm or less, 370 nm or less, 360 nm or less, 350 nm or less, 330 nm or less, 300 nm or less, 280 nm or less, 250 nm or less, 230 nm or less, 200 nm or less).

[0037] The method for measuring the thickness of layer (A) may be a known method and is not particularly limited, but for example, it may be measured by the method for measuring the thickness of layer (1) or layer (2) described in the embodiments below.

[0038] The thickness of layer (1) is not particularly limited, but from the viewpoint of adhesion between the polyimide film and the metal layer of the present invention, it may be, for example, 5 nm or more (e.g., 6 nm or more, 7 nm or more, 8 nm or more, 9 nm or more), preferably 10 nm or more (e.g., 11 nm or more, 12 nm or more, 13 nm or more, 14 nm or more, 15 nm or more).

[0039] The thickness (upper limit) of layer (1) is not particularly limited, but may be, for example, 150 nm or less (e.g., 140 nm or less, 130 nm or less, 120 nm or less, 110 nm or less), preferably 100 nm or less (e.g., 90 nm or less, 80 nm or less, 70 nm or less, 60 nm or less, 50 nm or less, 40 nm or less, 30 nm or less).

[0040] The method for measuring the thickness of layer (1) may be a known method and is not particularly limited, but for example, it may be measured by the method described in the examples below.

[0041] The thickness of layer (2) is not particularly limited, but may be, for example, 50 nm or more (e.g., 60 nm or more, 70 nm or more, 80 nm or more, 90 nm or more), preferably 100 nm or more (e.g., 110 nm or more, 120 nm or more, 130 nm or more, 140 nm or more, 150 nm or more).

[0042] The thickness (upper limit) of layer (2) is not particularly limited, but may be, for example, 350 nm or less (e.g., 340 nm or less, 330 nm or less, 320 nm or less, 310 nm or less), preferably 300 nm or less (e.g., 290 nm or less, 280 nm or less, 270 nm or less, 260 nm or less), and more preferably 250 nm or less (e.g., 240 nm or less, 230 nm or less, 220 nm or less, 210 nm or less, 200 nm or less).

[0043] The method for measuring the thickness of layer (2) may be a known method and is not particularly limited, but for example, it may be measured by the method described in the examples below.

[0044] (Polyimide film to which coupling agent is applied) The following describes the polyimide film on which the coupling agent is applied to the surface (i.e., the film to which the coupling agent is applied).

[0045] The thickness of the polyimide film can be appropriately selected depending on the application, but from the viewpoint of suitably using (functioning) it as a substrate (base film) for laminated films, for example, it may be about 1 μm or more (e.g., 2 μm or more), preferably 3 μm or more (e.g., 4 μm or more), and even more preferably 5 μm or more (e.g., 6 μm or more), and may also be about 7 μm or more (e.g., 8 μm or more, 10 μm or more, 12 μm or more, 15 μm or more, 18 μm or more, 20 μm or more, 22 μm or more, 25 μm or more, 28 μm or more, 30 μm or more, 32 μm or more, 35 μm or more).

[0046] The thickness (upper limit) of such polyimide film is not particularly limited, but may be, for example, 300 μm or less (e.g., 250 μm or less), preferably 200 μm or less (e.g., 150 μm or less), and more preferably 100 μm or less (e.g., 80 μm or less), or 70 μm or less (e.g., 60 μm or less, 55 μm or less, 50 μm or less, 45 μm or less, 40 μm or less, 35 μm or less, 30 μm or less).

[0047] Specific examples of polyimide film thicknesses include 1 to 200 μm, preferably 3 to 100 μm, and more preferably 5 to 80 μm.

[0048] A polyimide film may be a laminate of multiple polyimide films, but it is usually a single polyimide film.

[0049] The polyimide film may be an unstretched film or a stretched film (uniaxial or biaxially oriented film). In such a stretched film, the stretching conditions (e.g., stretching ratio in the TD direction and / or MD direction) may be those described below.

[0050] In this invention, sufficient adhesion and other properties can be efficiently achieved even in stretched films.

[0051] Composition, manufacturing method, etc. Polyimide films (or polyimides or polyamic acids that constitute polyimide films) typically contain aromatic diamine components and aromatic acid anhydride components as raw materials (these are the polymerization components).

[0052] Aromatic diamine components include, for example, paraphenylenediamine, 4,4'-diaminodiphenyl ether, 3,3'-diaminodiphenyl ether, 1,3-bis(3-aminophenoxy)benzene, 1,3-bis(4-aminophenoxy)benzene, 2,2-bis[4-(4-aminophenoxy)phenyl]propane, metaphenylenediamine, diaminodiphenylpropane (e.g., 4,4'-diaminodiphenylpropane, 3,4'-diaminodiphenylpropane, 3,3'-diaminodiphenylpropane, etc.), diamino Diphenylmethane (e.g., 4,4'-diaminodiphenylmethane, 3,4'-diaminodiphenylmethane, 3,3'-diaminodiphenylmethane, etc.), benzidine, diaminodiphenyl sulfide (e.g., 4,4'-diaminodiphenyl sulfide, 3,4'-diaminodiphenyl sulfide, 3,3'-diaminodiphenyl sulfide, etc.), diaminodiphenyl sulfone (e.g., 4,4'-diaminodiphenyl sulfone, 3,4'-diaminodiphenyl sulfone, 3,3'-diaminodiphenyl sulfone, etc.), 2 ,6-diaminopyridine, bis-(4-aminophenyl)diethylsilane, 3,3'-dichlorobenzidine, bis-(4-aminophenyl)ethylphosphinoxide, bis-(4-aminophenyl)phenylphosphinoxide, bis-(4-aminophenyl)-N-phenylamine, bis-(4-aminophenyl)-N-methylamine, 1,5-diaminonaphthalene, 3,3'-dimethyl-4,4'-diaminobiphenyl, 3,4'-dimethyl-3',4-diaminobiphenyl, 3,3'-dimethoxybenzidine, 2,4-bi Examples include p-(p-β-amino-t-butylphenyl) ether, bis(p-β-amino-t-butylphenyl) ether, p-bis(2-methyl-4-aminopentyl)benzene, p-bis-(1,1-dimethyl-5-aminopentyl)benzene, m-xylylenediamine, p-xylylenediamine, 2,5-diamino-1,3,4-oxadiazole, 2,2-bis(4-aminophenyl)hexafluoropropane, N-(3-aminophenyl)-4-aminobenzamide, and 4-aminophenyl-3-aminobenzoate. These can be used individually or in combination of two or more.

[0053] The aromatic diamine component may preferably contain at least one selected from paraphenylenediamine and 4,4'-diaminodiphenyl ether, and more preferably it may contain both paraphenylenediamine and 4,4'-diaminodiphenyl ether, from the viewpoint of efficiently achieving adhesion to the metal layer, heat resistance, dimensional stability, etc.

[0054] When the aromatic diamine component includes paraphenylenediamine and 4,4'-diaminodiphenyl ether, the molar ratio of paraphenylenediamine to 4,4'-diaminodiphenyl ether may be, for example, 60 / 40 to 1 / 99 (e.g., 55 / 45 to 5 / 95), preferably 50 / 50 to 10 / 90 (e.g., 45 / 55 to 15 / 85).

[0055] Examples of aromatic acid anhydride components (aromatic tetracarboxylic acid components) include pyromellitic dianhydride, 3,3',4,4'-biphenyltetracarboxylic acid dianhydride, 2,3',3,4'-biphenyltetracarboxylic acid dianhydride, 4,4'-oxydiphthalic acid anhydride, 3,3',4,4'-benzophenonetetracarboxylic acid dianhydride, 2,3,6,7-naphthalenedicarboxylic acid dianhydride, and 2,2-bis(3,4-dicarboxyphenyl) ether. Pyridine-2,3,5,6-tetracarboxylic acid dianhydride, naphthalenetetracarboxylic acid dianhydride (e.g., 1,2,4,5-naphthalenetetracarboxylic acid dianhydride, 1,4,5,8-naphthalenetetracarboxylic acid dianhydride, 1,4,5,8-decahydronaphthalenetetracarboxylic acid dianhydride, 4,8-dimethyl-1,2,5,6-hexahydronaphthalenetetracarboxylic acid dianhydride, 2,6-dichloro-1,4,5,8-naphthalenetetracarboxylic acid (Dianhydride of naphthalene, 2,7-dichloro-1,4,5,8-naphthalenetetracarboxylic acid dianhydride, 2,3,6,7-tetrachloro-1,4,5,8-naphthalenetetracarboxylic acid dianhydride, 1,8,9,10-phenanthrenetetracarboxylic acid dianhydride, 2,2-bis(2,3-dicarboxyphenyl)propane dianhydride, 1,1-bis(3,4-dicarboxyphenyl)ethane dianhydride, 1,1-bis(2,3-dicarboxyphenyl)ethane Examples include dianhydrides, bis(2,3-dicarboxyphenyl)methane dianhydrides, bis(3,4-dicarboxyphenyl)methane dianhydrides, bis(3,4-dicarboxyphenyl)sulfone dianhydrides, benzene-1,2,3,4-tetracarboxylic acid dianhydrides, 3,4,3',4'-benzophenonetetracarboxylic acid dianhydrides, and the like. Preferably, pyromellitic acid dianhydrides and 3,3',4,4'-biphenyltetracarboxylic acid dianhydrides are used. These can be used individually or in combination of two or more.

[0056] In combination with the aromatic diamine component as described above, the aromatic acid anhydride component preferably contains at least one selected from pyromellitic dianhydride and 3,3',4,4'-biphenyltetracarboxylic acid dianhydride, from the viewpoint of efficiently achieving adhesion to the metal layer, heat resistance, dimensional stability, etc., and more preferably contains pyromellitic dianhydride and 3,3',4,4'-biphenyltetracarboxylic acid dianhydride.

[0057] If the aromatic acid anhydride component includes at least one selected from pyromellitic dianhydride and 3,3',4,4'-biphenyltetracarboxylic acid dianhydride, the proportion of at least one selected from pyromellitic dianhydride and 3,3',4,4'-biphenyltetracarboxylic acid dianhydride to the total aromatic acid anhydride component (or total acid anhydride component) may be selected from a range of 30 mol% or more (for example, 40 to 100 mol%), for example, 50 mol% or more (for example, 60 mol% or more), preferably 70 mol% or more (for example, 80 mol% or more), and more preferably 90 mol% or more (for example, 95 mol% or more, 97 mol% or more, 98 mol% or more, 99 mol% or more, 100 mol%).

[0058] When the aromatic acid anhydride component includes pyromellitic dianhydride and 3,3',4,4'-biphenyltetracarboxylic acid dianhydride, the molar ratio of pyromellitic dianhydride to 3,3',4,4'-biphenyltetracarboxylic acid dianhydride may be, for example, 95 / 5 to 40 / 60 (e.g., 90 / 10 to 45 / 55), preferably 85 / 15 to 50 / 50 (e.g., 80 / 20 to 55 / 45).

[0059] The raw material components of the polyimide film (polymerization components, diamine components, and acid anhydride components) may also include other polymerization components (for example, other acid anhydride components, other diamine components) other than the above-mentioned aromatic acid anhydride components and aromatic diamine components, to the extent that they do not hinder the effects of the present invention. Other diamine components (non-aromatic diamine components) include, for example, diaminoadamantanes (e.g., 1,3-diaminoadamantan, 3,3'-diamino-1,1'-diaminoadamantan, 3,3'-diaminomethyl-1,1'-diadamantane, etc.) and diaminoalkanes (e.g., hexamethylenediamine, heptamethylenediamine, octamethylenediamine, nonamethylenediamine, decamethylenediamine, 3-methylheptamethylenediamine, 4,4'-dimethylheptamethylenediamine, 2,11-diaminododecane, 2,2-dimethylp Examples include propyldiamine, 3-methoxyhexaethylenediamine, 2,5-dimethylhexamethylenediamine, 2,5-dimethylheptamethylenediamine, 5-methylnonamethylenediamine, 1,4-diaminocyclohexane, 1,12-diaminooctadecane, etc., 1,2-bis(3-aminopropoxy)ethane, 2,5-diamino-1,3,4-oxadiazole, 2,2-bis(4-aminophenyl)hexafluoropropane, N-(3-aminophenyl)-4-aminobenzamide, 4-aminophenyl-3-aminobenzoate, etc. These can be used individually or in combination of two or more.

[0060] Furthermore, if the polymerization component contains other polymerization components (such as other diamine components), the proportion of the other polymerization components to the total polymerization component may be small, for example, 20 mol% or less (for example, 15 mol% or less, 10 mol% or less, 5 mol% or less, 3 mol% or less, 1 mol% or less).

[0061] Polyimide films may contain components other than polyimide (the resin component). For example, polyimide films may contain inorganic particles from the viewpoint of handling (ease of handling), etc. The other components may be present in one or more forms.

[0062] When inorganic particles are present, they are typically dispersed within the polyimide film. Examples of inorganic particles include oxides {e.g., SiO2 (silica), TiO2 (titanium(IV) oxide), etc.}, inorganic salts {e.g., phosphate (hydrogen) salts such as CaHPO4 (calcium hydrogen phosphate), CaPO4 (calcium phosphate), Ca2P2O7 (calcium diphosphate), and carbonates such as CaCO3 (calcium carbonate)}. Inorganic particles may be used individually or in combination of two or more types.

[0063] The average particle size of the inorganic particles used for dispersion may be, for example, 0.1 to 3.5 μm (e.g., 0.2 to 3 μm), preferably 0.3 to 2.5 μm, etc. Furthermore, the method for measuring the average particle size of inorganic particles is not particularly limited, and known methods may be used.

[0064] Regarding the particle size distribution of inorganic particles (inorganic particles used for dispersion), a narrow distribution is preferable, meaning that inorganic particles of similar size make up a high proportion of the total inorganic particles. Specifically, it is preferable that inorganic particles of a specific particle size (e.g., 0.5-2.5 μm, 1-3.5 μm, etc.) account for 80% or more (e.g., 80-100% by volume) of the total inorganic particles.

[0065] When inorganic particles are included, the proportion of inorganic particles in the polyimide film may be, for example, 0.01% by mass or more (e.g., 0.02% by mass or more), preferably 0.03% by mass or more (e.g., 0.04% by mass or more), and more preferably 0.05% by mass or more.

[0066] The upper limit of the proportion of inorganic particles in the polyimide film may be selected from a range of approximately 5% by mass or less (for example, 3% by mass or less, 2% by mass or less, 1.5% by mass or less), 1% by mass or less (for example, 0.9% by mass or less), preferably 0.8% by mass or less (for example, 0.7% by mass or less), and even more preferably 0.6% by mass or less (for example, 0.55% by mass or less, 0.5% by mass or less, 0.45% by mass or less, 0.4% by mass or less, 0.3% by mass or less), etc.

[0067] The polyimide film may be in a laminated state, and in particular, it may be in a wound state, i.e., in roll form. The width of the polyimide film (for example, a roll of polyimide film) is not particularly limited, but may be, for example, 30 mm or more, 45 mm or more, 50 mm or more, 75 mm or more, 100 mm or more, 150 mm or more, 200 mm or more, 300 mm or more, 500 mm or more, etc., or it may be 3000 mm or less, 2000 mm or less, 1000 mm or less, etc. The polyimide film may have a relatively large size. The length of such a polyimide film (for example, a roll of polyimide film) may be, for example, 1 m or more (for example, 5 m or more), 10 m or more (for example, 20 m or more), preferably 30 m or more (for example, 40 m or more), more preferably 50 m or more (for example, 100 m or more), and may also be 200 m or more, 300 m or more, 500 m or more, 1000 m or more, 2000 m or more, 3000 m or more, 5000 m or more, and so on.

[0068] The polyimide film may be surface-treated (e.g., by electrolytic treatment such as corona treatment or plasma treatment, or by blast treatment). Such surface treatment may be applied to one side or both sides. Furthermore, depending on the surface treatment (such as plasma treatment) and its degree, it may be a factor that reduces adhesion (for example, the values ​​embodied in T2 or T2 / T1 mentioned above) when exposed to conditions such as high temperatures. On the other hand, the present invention can achieve sufficient adhesion without surface treatment. Therefore, while the polyimide film may be plasma-treated, it may also be preferable to select a film that is not plasma-treated, or one that is treated to a minimal degree.

[0069] The method for producing polyimide films is not particularly limited, but representative methods are described below. To obtain a polyimide film, a polyamic acid solution (hereinafter also referred to as a polyamic acid solution) is first obtained by polymerizing the polymerization components (components including aromatic diamine components and aromatic acid anhydride components) in an organic solvent.

[0070] Specific examples of organic solvents used in the formation of polyamic acid solutions include sulfoxide solvents such as dimethyl sulfoxide and diethyl sulfoxide; formamide solvents such as N,N-dimethylformamide and N,N-diethylformamide; acetamide solvents such as N,N-dimethylacetamide and N,N-diethylacetamide; pyrrolidone solvents such as N-methyl-2-pyrrolidone and N-vinyl-2-pyrrolidone; phenolic solvents such as phenol, o-,m-, or p-cresol, xylenol, halogenated phenol, and catechol; and aprotic polar solvents such as hexamethylphosphoramide and γ-butyrolactone. These can be used individually or in combination of two or more. Furthermore, they may be used in combination with aromatic hydrocarbons such as xylene and toluene.

[0071] The polymerization method for the polyamic acid solution may be any known method, for example, (1) A method of polymerization in which the entire amount of the diamine component (aromatic diamine component) is first placed in the solvent, and then the acid anhydride component (aromatic acid anhydride component) is added in an amount equivalent to the total amount of the diamine component (aromatic diamine component), (2) A method of polymerization in which the entire amount of the acid anhydride component (aromatic acid anhydride component) is first placed in the solvent, and then the diamine component (aromatic diamine component) is added in an equivalent amount to the acid anhydride component (aromatic acid anhydride component), (3) A method of polymerization in which one diamine component (aromatic diamine component) is placed in a solvent, and then mixed for the time required for the reaction in a ratio in which one acid anhydride component (aromatic acid anhydride component) is 95 to 105 mol% relative to the reaction components, the other aromatic diamine component is added, and then the other acid anhydride component (aromatic acid anhydride component) is added so that the total diamine component (aromatic diamine component) and the total acid anhydride component (aromatic acid anhydride component) are approximately equivalent in amount. (4) A method of polymerization in which one acid anhydride component (aromatic acid anhydride component) is placed in a solvent, one diamine component (aromatic diamine component) is mixed for the time required for the reaction in a ratio of 95 to 105 mol% relative to the reaction components, the other acid anhydride component (aromatic acid anhydride component) is added, and then the other diamine component (aromatic diamine component) is added so that the total diamine component (aromatic diamine component) and the total acid anhydride component (aromatic acid anhydride component) are approximately equivalent in amount. (5) Prepare polyamic acid solution (A) by reacting one diamine component (aromatic diamine component) and an acid anhydride component (aromatic acid anhydride component) in a solvent such that one is in excess, and prepare polyamic acid solution (B) by reacting the other diamine component (aromatic diamine component) and an acid anhydride component (aromatic acid anhydride component) in a separate solvent such that one is in excess. Mix the resulting polyamic acid solutions (A) and (B) to complete the polymerization. When preparing polyamic acid solution (A), if there is an excess of diamine component (aromatic diamine component), polyamic acid solution (B) may contain an excess of acid anhydride component (aromatic acid anhydride component). Conversely, if there is an excess of acid anhydride component (aromatic acid anhydride component) in polyamic acid solution (A), polyamic acid solution (B) may contain an excess of diamine component (aromatic diamine component). By mixing polyamic acid solutions (A) and (B), the total amount of diamine component (aromatic diamine component) and total amount of acid anhydride component (aromatic acid anhydride component) used in these reactions may be adjusted to be approximately equivalent. The polymerization method is not limited to these methods, and other known methods may also be used.

[0072] The acid anhydride component (aromatic acid anhydride component) and the diamine component (aromatic diamine component) that constitute the polyamic acid are polymerized in a ratio in which the number of moles of each is approximately equal, but one may be added in excess of the other within the range of 10 mol%, preferably 5 mol%.

[0073] The polymerization reaction is preferably carried out in an organic solvent with stirring. The polymerization temperature is not particularly limited, but is usually carried out at an internal temperature of 0 to 80°C in the reaction solution. The polymerization time is not particularly limited, but is preferably carried out continuously for 10 minutes to 30 hours. The polymerization reaction may be divided into stages or the temperature may be raised or lowered as needed. There are no particular restrictions on the order in which the two reactants are added, but it is preferable to add the aromatic acid anhydride to the solution of the aromatic diamine component. Vacuum degassing during the polymerization reaction is an effective method for producing a high-quality organic solvent solution of polyamic acid. Furthermore, the polymerization reaction may be controlled by adding a small amount of end-capping agent to the aromatic diamines before the polymerization reaction. The end-capping agent is not particularly limited, and known ones can be used.

[0074] The resulting polyamic acid solution may contain a solid content of typically 5 to 40% by mass, preferably 10 to 30% by mass. Its viscosity is not particularly limited, but the measurement using a Brookfield viscometer is typically 10 to 2000 Pa·s, and preferably 100 to 1000 Pa·s for stable liquid delivery. Furthermore, the polyamic acid in the organic solvent solution may be partially imidized.

[0075] When obtaining a polyimide film containing inorganic particles, the inorganic particles may be included in the polyamic acid solution. When obtaining a polyamic acid solution containing inorganic particles, the inorganic particles may be added to a pre-polymerized polyamic acid solution, or the polyamic acid solution may be polymerized in the presence of the inorganic particles.

[0076] It is preferable to use inorganic particles as a slurry (inorganic particle slurry) dispersed in a solvent (for example, polar solvents such as N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, and N-methylpyrrolidone) because this prevents aggregation.

[0077] The method for producing the inorganic particle slurry is not particularly limited and may follow conventionally known methods. Examples of methods for producing the inorganic particle slurry include mixing inorganic particles and a solvent using a mixer. It is preferable to use a mixer with high shear force, such as a high-speed disperser, homomixer, ball mill, coreless mixer, or agitated disperser. Alternatively, wet grinding may be performed to reduce the average particle size. For wet grinding, for example, a bead mill or sand mill can be used.

[0078] As the inorganic particle slurry, a commercially available product in which inorganic particles are pre-dispersed in a solvent may be used. Furthermore, the inorganic particle slurry may contain other organic solvents or compounding agents as needed.

[0079] The concentration of inorganic particles in the inorganic particle slurry is not particularly limited, but is, for example, 1 to 80% by mass, preferably 1 to 60% by mass, and more preferably 1 to 40% by mass.

[0080] Furthermore, filtering the inorganic particle slurry through a filter having a predetermined pore size (for example, a cut filter with a pore size of 15 μm or less, preferably 13 μm or less, more preferably 11 μm or less, even more preferably 5 μm or less, and particularly preferably 3 μm or less) is preferable from the viewpoint that it can suppress aggregation of inorganic particles and remove inorganic particles of a predetermined particle size (for example, inorganic particles of 15 μm or more) from the polyimide film.

[0081] The material of the filter is not particularly limited and includes, for example, polymer materials (e.g., polyethylene, polypropylene, polytetrafluoroethylene, etc.) and metals (e.g., stainless steel, etc.).

[0082] The amount of inorganic particles added should be appropriately selected to correspond to the desired content in the polyimide film (for example, so that when the polyimide is formed, the amount is 0.03 to 0.8 parts by mass per 100 parts by mass of polyimide).

[0083] Next, a method for manufacturing polyimide films will be described. Polyimide films can be manufactured, for example, by a process (1) of cyclizing a polyamic acid solution to obtain a gel film (converting polyamic acid or a polyamic acid solution into a gel film), and a process (2) of drying (and desolvation) the obtained gel film and heat treatment. Note that drying and imidization proceed during drying and heat treatment.

[0084] In step (1), the method for cyclizing the polyamic acid solution is not particularly limited, but specifically, examples include (i) a method of casting the polyamic acid solution into a film and obtaining a gel film by thermal dehydration and cyclization (thermal cyclization method), or (ii) a method of mixing a catalyst (cyclization catalyst) and a dehydrating agent (converter) with the polyamic acid solution, chemically decyclizing it to produce a gel film, and obtaining the gel film by heating (chemical cyclization method), with the latter method (chemical cyclization method) being particularly preferred.

[0085] Surprisingly, the chemical ring-closing method (and furthermore, the selection of the polymerization components as described above while also selecting the chemical ring-closing method) seems to efficiently yield the physical properties (characteristics) required for the polyimide film of the present invention. Furthermore, the chemical ring-closing method is also suitable from the viewpoint of mass production.

[0086] The above polyamic acid solution may contain a gel retarder, etc. The gel retarder is not particularly limited, and acetylacetone, etc., can be used.

[0087] Examples of cyclization catalysts include amines, such as aliphatic tertiary amines (trimethylamine, triethylenediamine, etc.), aromatic tertiary amines (dimethylaniline, etc.), and heterocyclic tertiary amines (e.g., isoquinoline, pyridine, β-picoline, etc.). These may be used individually or in combination of two or more. Of these, heterocyclic tertiary amines such as β-picoline are preferred.

[0088] Examples of dehydrating agents include acid anhydrides, such as aliphatic carboxylic acid anhydrides (e.g., acetic anhydride, propionic anhydride, butyric anhydride, etc.) and aromatic carboxylic acid anhydrides (e.g., benzoic anhydride, etc.). These may be used individually or in combination of two or more. Among these, acetic anhydride and / or benzoic anhydride are preferred, and acetic anhydride is particularly preferred.

[0089] The amounts of cyclization catalyst and dehydrating agent used are not particularly limited, but may be, for example, 1 mole or more (for example, about 1.5 to 10 moles) per mole of amide group (or carboxyl group) of polyamic acid (or polyamic acid).

[0090] Gel films can usually be obtained by casting (coating) a polyamic acid solution (particularly a polyamic acid solution mixed with a cyclization catalyst and a converter) onto a support, and then partially drying and curing (imidizing) it.

[0091] More specifically, a polyamic acid solution may be cast onto a support through a slit nozzle to form a film, heated by heat from the support, hot air, or an electric heater to induce a ring-closing reaction, and then dried to form a gel film, which is then peeled off the support.

[0092] Here, the gel film needs to have self-supporting properties in order to be peelable, but the characteristics of gel films obtained by chemical cyclization and gel films obtained by thermal cyclization usually differ significantly. In other words, in chemical cyclization, gelation (conversion) can be achieved with a catalyst, resulting in a self-supporting gel film (flexible or wet gel film) containing a large amount of solvent. In contrast, in thermal cyclization, a large amount of heat treatment is required for gelation (to give it self-supporting properties), resulting in a relatively hard gel film (with little residual solvent).

[0093] The support is not particularly limited, but examples include a rotating drum made of metal (e.g., stainless steel), an endless belt, etc. The temperature of the support is not particularly limited, and may be, for example, 30 to 200°C, preferably 40 to 150°C, and more preferably 50 to 120°C. The temperature of the support can be controlled by (i) a liquid or gaseous heat transfer medium, or (ii) radiant heat from an electric heater, etc.

[0094] In step (2), the gel film is dried (solvent removed) and then heat-treated. Typically, step (2) may include a step in which the gel film is held at both ends in the width direction and passed through a heating furnace (such as a tenter heating furnace) to dry it, and then heat-treated.

[0095] Specifically, the gel film peeled from the support is not particularly limited, but is usually stretched in the transport direction while the travel speed is controlled by a rotating roll. The thickness of the polyimide film may be adjusted by the travel speed.

[0096] Stretching in the conveying direction may be carried out at a predetermined temperature (for example, a temperature of 140°C or lower). The stretching ratio (MDX) is usually 1.05 to 1.9 times, preferably 1.1 to 1.6 times, and more preferably 1.1 to 1.5 times (for example, 1.15 to 1.4 times).

[0097] In drying, the drying temperature may be, for example, 210°C or higher (e.g., 213-500°C), preferably 215°C or higher (e.g., 218-400°C), and more preferably 220°C or higher (e.g., 220-300°C).

[0098] Furthermore, drying may be carried out while suppressing uneven drying (variation) in the film width direction. For example, uneven drying temperature in the film width direction may be less than 25°C (e.g., 0-24°C), preferably 22°C or less (e.g., 1-21°C), more preferably 20°C or less (e.g., 2-19°C), and particularly 18°C ​​or less (e.g., 3-18°C).

[0099] Furthermore, uneven drying temperature can be measured by taking multiple points at predetermined intervals (e.g., 200 mm) along the film width direction and determining the difference (width) between the maximum and minimum measured drying temperatures.

[0100] The gel film (especially a gel film stretched in the transport direction) is heat-treated after drying. The heat treatment temperature is not particularly limited and may be, for example, 200°C or higher (e.g., 250-600°C), preferably 300°C or higher, and more preferably 350°C or higher.

[0101] As mentioned above, the L value can be efficiently adjusted by adjusting or setting the heat treatment temperature (for example, setting the maximum heating temperature) (and also by combining it with other conditions).

[0102] Furthermore, after drying, the material may be stretched in the width direction. This stretching in the width direction may be carried out in conjunction with heat treatment.

[0103] In stretching in the width direction, the stretching ratio (TDX) may be, for example, 1.05 to 1.9 times, preferably 1.1 to 1.6 times, and more preferably 1.1 to 1.5 times (for example, 1.15 to 1.4 times).

[0104] Furthermore, the physical properties (characteristics) required for polyimide films (and more specifically, the polyimide films of the present invention) can sometimes be efficiently adjusted by such stretching and the conditions under which it is stretched (and even in combination with other conditions).

[0105] A polyimide film is obtained in this way. The obtained polyimide film may be further annealed.

[0106] The annealing method is not particularly limited, and known methods may be used. The temperature of the annealing process is not particularly limited, but may be, for example, 200 to 500°C, preferably 200 to 370°C, and more preferably 210 to 350°C. Specifically, the annealing process may be carried out by running the film through a furnace heated to the above temperature range under low tension. The film tension during running may be, for example, 10 to 50 N / m, more preferably 20 to 30 N / m.

[0107] Plasma treatment may be performed on the polyimide film (or its surface) obtained as described above. Plasma treatment may be performed on both sides of the polyimide film or on one side. Furthermore, as mentioned above, when considering adhesion when exposed to conditions such as high temperatures, it is sometimes preferable not to perform plasma treatment on polyimide films, or to perform plasma treatment to a small extent.

[0108] The plasma treatment method is not particularly limited, and known methods may be used. The processing gas for plasma treatment is not particularly limited, but examples include inert gases (e.g., He, Ar, Kr, Xe, Ne, Rn, N2, etc.), O2, H2O, air, CO2, etc. The processing gas may be used individually or in combination of two or more types.

[0109] The processing pressure for plasma treatment is not particularly limited, but may be, for example, 0.1 Pa to 1330 kPa. The processing intensity (E value) of the plasma treatment is not particularly limited, but for example, 50 W·min / m 2 More than 75W min / m 2 The above may also be acceptable, and the 2000W·min / m 2 Below, 1800W min / m 2 The following are also acceptable. The processing time for plasma treatment is not particularly limited, but may be, for example, 1 second to 10 minutes.

[0110] The physical properties (characteristics) of the polyimide film to be coated with the coupling agent (e.g., glass transition temperature, coefficient of linear expansion, etc.) may correspond to the physical properties (characteristics) of the polyimide film of the present invention (hereinafter sometimes simply referred to as "polyimide film 1"). In other words, the physical properties (characteristics) of the polyimide film to be coated with the coupling agent (e.g., glass transition temperature, coefficient of linear expansion, etc.) may be the same as those of the polyimide film 1 described later.

[0111] (Method for producing polyimide film according to the present invention) The method for producing the polyimide film (polyimide film 1) of the present invention will be described below.

[0112] The method for producing polyimide film 1 includes the step of applying a coupling agent-containing solution to one or both sides of the polyimide film, and then drying it. As the polyimide film to which the coupling agent-containing solution is applied, a polyimide film may be used instead of a polyamic acid gel film.

[0113] The coupling agent-containing solution may typically contain a coupling agent and a solvent, and may optionally contain other components {for example, surface treatment agents other than the coupling agent {for example, silane compounds [for example, mono- to tetraalkoxysilanes such as tetramethoxysilane and tetraethoxysilane, preferably mono- to tetraC1-4 alkoxysilanes]}}.

[0114] A coupling agent-containing solution can be prepared, for example, by mixing the coupling agent and a solvent (and other components as needed).

[0115] The solvent is not particularly limited and includes, for example, water, alcohols (e.g., methanol, ethanol, etc.), esters (e.g., organic acid esters such as ethyl lactate and ethyl acetate), and from the viewpoint of the reactivity of the coupling agent (e.g., the reactivity between the reactive functional group and the polyimide), esters, alcohols, etc. may be preferred. One or more solvents may be used. Furthermore, it is preferable to use a solvent different from the one used to form the polyamic acid solution (for example, a solvent other than N,N-dimethylacetamide) as the solvent.

[0116] The content of the coupling agent in the coupling agent-containing solution may be, for example, 0.05% by mass or more (e.g., 0.1% by mass or more), preferably 0.5% by mass or more (e.g., 1% by mass or more), from the viewpoint of the reactivity of the coupling agent and the formation of layer (A) on the surface of the polyimide film, and may also be, for example, 10% by mass or less (e.g., 7% by mass or less), preferably 5% by mass or less (e.g., 3% by mass or less).

[0117] When the solvent contains an organic acid ester (e.g., ethyl lactate), the proportion of the organic acid ester (e.g., ethyl lactate) to the total solvent may be, for example, 30 parts by mass or more (e.g., 40 parts by mass or more), preferably 50 parts by mass or more (e.g., 60 parts by mass or more, 70 parts by mass or more), and more preferably 80 parts by mass or more (e.g., 90 parts by mass or more), from the viewpoint of the reactivity of the coupling agent (e.g., the reactivity of the reactive functional group with the polyimide).

[0118] When the solvent contains an organic acid ester (e.g., ethyl lactate), the proportion (upper limit) of the organic acid ester (e.g., ethyl lactate) to the total solvent is not particularly limited, but may be, for example, 99 parts by mass or less (e.g., 98 parts by mass or less, 97 parts by mass or less, 96 parts by mass or less, 95 parts by mass or less).

[0119] In drying, the drying temperature may be, for example, 100°C or higher (e.g., 110°C or higher, 120°C or higher), preferably 130°C or higher (e.g., 140°C or higher), from the viewpoint of forming layer (A) on the surface of the polyimide film and the adhesion between the polyimide film and the metal layer of the present invention, and may also be, for example, 280°C or lower (e.g., 250°C or lower), 220°C or lower (e.g., 210°C or lower), preferably 200°C or lower (e.g., 190°C or lower).

[0120] In drying, the drying time depends on the drying temperature and other factors, but from the viewpoint of forming layer (A) on the surface of the polyimide film and the adhesion between the polyimide film of the present invention and the metal layer, it may be, for example, 20 seconds or more (e.g., 30 seconds or more), preferably 40 seconds or more (e.g., 50 seconds or more, 60 seconds or more), or for example, 150 seconds or less (e.g., 140 seconds or less, 130 seconds or less), preferably 120 seconds or less (e.g., 110 seconds or less, 100 seconds or less).

[0121] (The present invention: polyimide film) The polyimide film of the present invention (polyimide film 1) typically possesses certain physical properties.

[0122] Polyimide film 1 often satisfies at least one of the following physical properties, and typically, it may satisfy at least adhesion (peel strength to the metal layer) [in particular, adhesion and one or more of the other physical properties]. The following physical properties can be efficiently satisfied, for example, by the composition of the polyimide (of the polyimide film to be coated with the coupling agent), the thickness of the film, the manufacturing conditions of the film, and combinations of these (selection and adjustment). Furthermore, polyimide film 1 is more likely to maintain the physical properties (characteristics) (e.g., glass transition temperature, coefficient of thermal expansion, etc.) of the polyimide film to which the coupling agent is applied.

[0123] The polyimide film 1 can achieve sufficient adhesion to the metal layer. Examples of such polyimide films 1 include those in which, when the metal layer is directly laminated (laminated without an adhesive layer) on the polyimide film 1, the peel strength (adhesion strength, peel strength, 90° peel strength) value (T1) between the metal layer and the polyimide film 1 is greater than 0.3 kN / m (for example, 0.35 kN / m or more), preferably 0.4 kN / m or more (for example, 0.45 kN / m or more), and more preferably 0.5 kN / m or more.

[0124] The upper limit of T1 is not particularly limited, but may be, for example, 5kN / m or less, 4kN / m or less, 3kN / m or less, 2.5kN / m or less, 2kN / m or less, 1.5kN / m or less, 1.2kN / m or less, 1kN / m or less, etc.

[0125] Such adhesion can be maintained at a relatively high level even when subjected to conditions such as high temperatures (e.g., harsh conditions). Examples of such polyimide films 1 include polyimide films in which, when the peel strength (adhesion, peel strength) between the metal layer and the polyimide film 1 is T1 when the metal layer is directly laminated (laminated without an adhesive layer) on the polyimide film 1, and T2 is the peel strength (adhesion, peel strength) between the metal layer and the polyimide film 1 after heating at 150°C for 168 hours, T2 / T1 is 0.3 or more (e.g., 0.4 or more), preferably 0.5 or more (e.g., greater than 0.5, 0.55 or more), more preferably 0.6 or more (e.g., 0.65 or more), particularly 0.7 or more (e.g., 0.72 or more), and particularly preferably 0.75 or more (e.g., greater than 0.75, 0.78 or more, 0.8 or more).

[0126] Note that the upper limit of T2 / T1 may be 1, or less than 1 (for example, 0.99 or less, 0 It may also be 0.98 or less, 0.97 or less, 0.96 or less, 0.95 or less, 0.94 or less, 0.93 or less, 0.92 or less, 0.91 or less, or 0.9 or less.

[0127] Furthermore, the value of T2 may be, for example, greater than 0.2 kN / m (for example, 0.25 kN / m or more), preferably 0.3 kN / m or more (for example, 0.35 kN / m or more), and even more preferably 0.4 kN / m or more.

[0128] The upper limit of T2 is not particularly limited, but may be, for example, 5kN / m or less, 4kN / m or less, 3kN / m or less, 2.5kN / m or less, 2kN / m or less, 1.5kN / m or less, 1.2kN / m or less, 1kN / m or less, 0.9kN / m or less, 0.8kN / m or less, etc.

[0129] In addition, in the measurement of T1 (and furthermore T2), the metal layer is not particularly limited, but may be a specific metal layer {for example, one corresponding to the embodiment described later, i.e., a copper layer with a thickness of 8.5 μm [for example, a copper layer with a thickness of 8.5 μm (for example, a layer formed by plating) laminated via a nickel / chromium alloy (nickel / chromium = 80 / 20) layer with a thickness of 25 nm (for example, a layer formed by sputtering) and a copper layer with a thickness of 100 nm (for example, a layer formed by sputtering) formed on this layer]}.

[0130] The measurement method for T1 (and even T2) may be, for example, one that conforms to Method A in the test method for the peel strength of copper foil described in JIS C 6471 (e.g., tensile angle 90°, tensile speed 50 mm / min). More specifically, T1 (and even T2) may be measured by the method described in the examples below.

[0131] In the polyimide film 1, the coefficient of linear expansion αMD in the MD direction (direction perpendicular to the machine transport direction, longitudinal direction, length direction, longitudinal direction, and width direction (TD direction)) may be selected from a range of approximately 50 ppm / K or less (for example, 40 ppm / K or less, 35 ppm / K or less, 30 ppm / K or less, 25 ppm / K or less), and from the viewpoint of dimensional stability (for example, dimensional stability when laminating metal layers such as copper), it may be, for example, approximately 20 ppm / K or less (for example, 18 ppm / K or less), preferably 16 ppm / K or less (for example, 15 ppm / K or less), and even more preferably 14 ppm / K or less (for example, 13 ppm / K or less), or 12 ppm / K or less (for example, 11 ppm / K or less, 10 ppm / K or less).

[0132] The lower limit of αMD may be 0 ppm / K, greater than 0 ppm / K [for example, from the viewpoint of dimensional stability (for example, dimensional stability when laminating metal layers such as copper), 1 ppm / K or more (e.g., 1.5 ppm / K or more), preferably 2 ppm / K or more (e.g., 2.5 ppm / K or more), and more preferably 3 ppm / K or more (e.g., 3.5 ppm / K or more)], or 4 ppm / K or more (e.g., 4.5 ppm / K or more, 5 ppm / K or more, 5.5 ppm / K or more, 6 ppm / K or more, 6.5 ppm / K or more, 7 ppm / K or more).

[0133] Specific αMD values ​​may be, for example, 0 to 30 ppm / K, and from the viewpoint of dimensional stability (e.g., dimensional stability when laminating metal layers such as copper), preferably 1 to 20 ppm / K (e.g., 2 to 18 ppm / K), and more preferably 3 to 17 ppm / K (e.g., 4 to 16 ppm / K, 5 to 15 ppm / K, 6 to 14 ppm / K, 6 to 12 ppm / K, 6 to 10 ppm / K), etc.

[0134] In the polyimide film 1, the coefficient of linear expansion αTD in the TD direction (width direction, transverse direction, perpendicular direction, direction perpendicular to the vertical direction (MD) direction) may be selected from a range of approximately 50 ppm / K or less (for example, 40 ppm / K or less, 35 ppm / K or less, 30 ppm / K or less, 25 ppm / K or less), and from the viewpoint of dimensional stability (for example, dimensional stability when laminating a metal layer such as copper), it may be, for example, 20 ppm / K or less (for example, 18 ppm / K or less), preferably 16 ppm / K or less (for example, 15 ppm / K or less), and even more preferably 14 ppm / K or less (for example, 13 ppm / K or less), or 12 ppm / K or less (for example, 11 ppm / K or less, 10 ppm / K or less, 9 ppm / K or less, 8 ppm / K or less, 7 ppm / K or less, 6 ppm / K or less, 5 ppm / K or less), etc.

[0135] The lower limit of αTD may be, for example, -10 ppm / K or higher (e.g., -9 ppm / K or higher, -8 ppm / K or higher, -7 ppm / K or higher, -6 ppm / K or higher), -5 ppm / K or higher (e.g., -4 ppm / K or higher, -3 ppm / K or higher, -2 ppm / K or higher, -1 ppm / K or higher), 0 ppm / K or higher, or greater than 0 ppm / K [e.g., 1 ppm / K or higher (e.g., 1.5 ppm / K or higher)], and preferably 2 ppm / K or higher.

[0136] Specific αTD values ​​may be, for example, -10 to 30 ppm / K, preferably -10 to 20 ppm / K (e.g., -8 to 18 ppm / K), and more preferably -5 to 17 ppm / K (e.g., -5 to 15 ppm / K, -5 to 10 ppm / K, -5 to 8 ppm / K), from the viewpoint of dimensional stability (e.g., dimensional stability when laminating metal layers such as copper).

[0137] In the polyimide film 1, the value of (|αMD|+|αTD|) / 2 may be selected from a range of approximately 50 ppm / K or less (for example, 40 ppm / K or less, 35 ppm / K or less, 30 ppm / K or less, 25 ppm / K or less), and from the viewpoint of dimensional stability (for example, dimensional stability when a metal layer such as copper is laminated), it may be, for example, 20 ppm / K or less (for example, 18 ppm / K or less), preferably 16 ppm / K or less (for example, 15 ppm / K or less), and even more preferably 14 ppm / K or less (for example, 13 ppm / K or less), or 12 ppm / K or less (for example, 11 ppm / K or less, 10 ppm / K or less), etc.

[0138] The lower limit of (|αMD|+|αTD|) / 2 may be 0 ppm / K, greater than 0 ppm / K [for example, 1 ppm / K or more (e.g., 1.5 ppm / K or more), preferably 2 ppm / K or more (e.g., 2.5 ppm / K or more), and more preferably 3 ppm / K or more (e.g., 3.5 ppm / K or more), from the viewpoint of dimensional stability (e.g., dimensional stability when laminating metal layers such as copper)], or 4 ppm / K or more (e.g., 4.5 ppm / K or more, 5 ppm / K or more).

[0139] The specific (|αMD|+|αTD|) / 2 can be, for example, 0 to 30 ppm / K, and from the viewpoint of dimensional stability (for example, dimensional stability when laminating metal layers such as copper), it may be preferably 1 to 20 ppm / K (for example, 2 to 18 ppm / K), and more preferably 3 to 17 ppm / K (for example, 4 to 16 ppm / K, 4 to 15 ppm / K, 5 to 14 ppm / K), etc.

[0140] In polyimide film 1, the absolute value of the difference between |αMD| and |αTD| (|αMD|-|αTD|) may be selected from a range of approximately 30 ppm / K or less (for example, 25 ppm / K or less, 20 ppm / K or less), and from the viewpoint of dimensional stability (for example, dimensional stability when laminating a metal layer such as copper), it may be, for example, 15 ppm / K or less (for example, 12 ppm / K or less), preferably 10 ppm / K or less (for example, 8 ppm / K or less), and even more preferably 7 ppm / K or less (for example, 6 ppm / K or less), or 5 ppm / K or less (for example, 4.5 ppm / K or less, 4 ppm / K or less, 3.5 ppm / K or less, 3 ppm / K or less, 2.5 ppm / K or less, 2 ppm / K or less, 1.5 ppm / K or less, 1 ppm / K or less), etc.

[0141] The absolute value (lower limit) of the difference between |αMD| and |αTD| (|αMD|-|αTD|) may be 0 ppm / K, or it may be greater than 0 ppm / K (for example, 0.1 ppm / K or more, 0.2 ppm / K or more, 0.3 ppm / K or more, 0.4 ppm / K or more, 0.5 ppm / K or more).

[0142] Note that αMD and αTD are not particularly limited, but may be measured within a specific temperature range (e.g., 50 to 200°C) or under specific conditions (e.g., a heating rate of 10°C / min). Specifically, they may be measured using the method described in the examples below.

[0143] The glass transition temperature (Tg) of the polyimide film 1 (or the polyimide constituting the polyimide film, hereinafter the same) may be selected from a range of approximately 400°C or less (for example, 395°C or less) from the viewpoint of adhesion with the metal layer, and preferably 390°C or less (for example, 385°C or less), and more preferably 380°C or less (for example, 375°C or less).

[0144] The Tg (lower limit of Tg) of polyimide film 1 may be selected from a range of approximately 150°C or higher (for example, 160°C or higher, 170°C or higher), preferably 180°C or higher (for example, 190°C or higher), preferably 200°C or higher (for example, 210°C or higher), and even more preferably 220°C or higher (for example, 22 It may be 5°C or higher, or 230°C or higher (for example, 235°C or higher, 240°C or higher, 245°C or higher, 250°C or higher, 255°C or higher, 260°C or higher, 265°C or higher, 270°C or higher, 275°C or higher, 280°C or higher, 285°C or higher, 290°C or higher, 295°C or higher, 300°C or higher, 305°C or higher, 310°C or higher, 315°C or higher, 320°C or higher, 325°C or higher, 330°C or higher), etc.

[0145] Furthermore, you may choose a range by combining these ranges (upper and lower limits) as appropriate (for example, 200-400°C, 230-390°C, etc.; the same applies to the range descriptions below).

[0146] Specific Tg values ​​for polyimide film 1 include, for example, 180 to 400°C, preferably 200 to 390°C, and more preferably 220 to 380°C.

[0147] The method for measuring Tg may be any known method and is not particularly limited; for example, the tanδ method (i.e., the value where the peak intensity of tanδ is used as Tg) may be used.

[0148] In polyimide film 1, the thickness ratio between the polyimide film (polyimide film to be coated with coupling agent) and layer (A) can be selected according to the application, etc. For example, the thickness ratio of polyimide film to be coated with coupling agent / layer (A) (thickness ratio) may be selected from a range of about 30000 / 1 to 10 / 1 (for example, 20000 / 1 to 30 / 1), or it may be about 10000 / 1 to 40 / 1 (for example, 8000 / 1 to 50 / 1), preferably 6000 / 1 to 60 / 1 (for example, 5000 / 1 to 50 / 1), and even more preferably 3000 / 1 to 70 / 1 (for example, 2900 / 1 to 80 / 1, 2800 / 1 to 100 / 1, 2700 / 1 to 200 / 1).

[0149] The dielectric breakdown voltage of the polyimide film 1 may be, for example, 445kV / mm or higher (e.g., 448kV / mm or higher), preferably 450kV / mm or higher (e.g., 453kV / mm or higher), and more preferably 455kV / mm or higher (e.g., 458kV / mm or higher, 460kV / mm or higher). The upper limit of the dielectric breakdown voltage of the polyimide film 1 is not particularly limited, but may be, for example, 700kV / mm or less (e.g., 650kV / mm or less), preferably around 630kV / mm or less (e.g., 600kV / mm or less, 580kV / mm or less, 550kV / mm or less). Although it was expected that the dielectric breakdown voltage of polyimide film 1 would be lower due to the decomposition of hydrolyzed condensates of the coupling agent, etc., the high dielectric breakdown voltage of polyimide film 1 was an unexpected effect. The reason why polyimide film 1 has a high dielectric breakdown voltage is not entirely clear, but it is presumed that the presence of layer (A) in polyimide film 1 forms chemical bonds on the surface of the polyimide film, reducing the non-uniformity (roughness) of the polyimide film surface, which increases the number of contact points with the electrodes and hinders localized conductivity, or that layer (A) prevents conductivity due to moisture.

[0150] The dielectric breakdown voltage of polyimide film 1 may be selected by appropriately combining these ranges (upper and lower limits) (for example, 450-600 kV / mm).

[0151] The method for measuring dielectric breakdown voltage is not particularly limited, but for example, it may be measured by a method conforming to the flat-plate electrode method of JIS C 2151.

[0152] [Applications of polyimide films, such as metal laminated films] The polyimide film of the present invention is suitable for use in lamination of metals (metal layers).

[0153] Such polyimide films can also be laminated with metal (metal layers) directly, without the need for an adhesive layer. Therefore, they are also suitable as polyimide films for laminating metal (metal layers) directly, without the need for an adhesive layer.

[0154] Furthermore, polyimide films can be efficiently laminated (formed) with metal (metal layers) by metallizing (plating, etc.). Therefore, the polyimide film of the present invention is also suitable for metallizing.

[0155] The following describes suitable uses of such polyimide films.

[0156] As described above, polyimide films can be made into laminated films by laminating metal (metal layers).

[0157] Such laminated films can be described as laminated films (metal-laminated polyimide films, metal-laminated films) composed of a polyimide film and a metal layer (metal) laminated on this film.

[0158] In a laminated film, the metal layer may typically be laminated (formed) on the polyimide film without an adhesive layer (or directly).

[0159] In such a laminated film, the metal layer may be a metal foil or the like, or it may be formed by metallization, but it is preferably formed by metallization.

[0160] Metallizing (metallizing methods) are not particularly limited, but typical examples include plating (plating methods). Specific examples of metallizing include wet plating (e.g., electroplating) and dry plating (e.g., vacuum deposition, sputtering, ion plating, etc.).

[0161] These methods may be used individually or in combination of two or more. An example of combining two or more methods is, for instance, when a metal layer is composed of a base layer and an upper layer, as described later, the base layer may be formed by a dry plating method (for example, relatively thinly) and the upper layer by a wet plating method.

[0162] The metals that make up the metal layer are not particularly limited, but examples include metals such as copper, nickel, chromium, manganese, aluminum, iron, molybdenum, cobalt, tungsten, vanadium, titanium, and talc, as well as alloys of these metals, oxides of these metals, and carbides of these metals.

[0163] The metals constituting the metal layer may be one or more types of metals.

[0164] The metal layer may be a single layer or multiple layers (for example, two to three layers).

[0165] For example, a metal layer may consist of a base layer (underlying metal layer, base metal layer) and an upper layer (upper metal layer, wiring layer) laminated (formed) on this base layer. Furthermore, the base layer and upper layer (for example, the base layer) may also be multi-layered.

[0166] Furthermore, if the metal layers are multilayered, the metals constituting each layer may be the same or different.

[0167] Taking a copper laminated film as an example, the metal layer in the copper laminated film may consist only of a copper layer, or a copper layer (upper layer) may be formed via a base layer (base metal layer). In this case, the base layer may consist of one or two or more layers, and may consist of at least one selected from copper and non-copper metals.

[0168] Specific examples of metal layers with a copper layer as the top layer include a base layer (e.g., a sputtering layer) consisting of at least one layer selected from a copper layer, a non-copper metal layer (e.g., a nickel / chromium layer), and combinations thereof, and a copper layer (e.g., a plating layer) laminated on this base layer.

[0169] The metal layer may be formed on one side of the polyimide film or on both sides. Furthermore, when using a plasma-treated polyimide film, the metal layer may be formed on the plasma-treated side of the polyimide film.

[0170] The thickness of the metal layer (total thickness in the case of a multilayer, or the thickness of each metal layer if provided on both sides) can be appropriately selected depending on the application and the characteristics of the metal layer, and may be 1 nm or more (for example, 2 nm to 100 μm), 3 nm or more (for example, 5 nm to 50 μm), etc.

[0171] In particular, in printed circuit boards and the like, the thickness of the metal layer [for example, a copper layer (including a metal layer with a copper layer as the top layer)] may be 1 μm or more (for example, 1 to 50 μm, 2 to 40 μm), preferably 3 μm or more (for example, 3 to 30 μm, 4 to 25 μm, 3 to 20 μm), and more preferably 5 μm or more (for example, 5 to 30 μm, 5 to 20 μm, 5 to 15 μm), etc.

[0172] When the metal layer includes an underlying layer, the thickness of the underlying layer is not particularly limited, but may be, for example, 1 to 500 nm (e.g., 5 to 200 nm).

[0173] When the metal layer includes the underlying layer, the ratio of the thickness of the underlying layer to the total thickness of the metal layer may be selected from a range of, for example, 30% or less, or 20% or less (for example, 15% or less, 10% or less, 5% or less, 3% or less, 2% or less), etc.

[0174] In particular, the thickness of the metal layer may be relatively small (thin), for example, 50 μm or less (for example, 40 μm or less), preferably 30 μm or less (for example, 25 μm or less), and more preferably 20 μm or less (for example, 15 μm or less, 12 μm or less, 10 μm or less).

[0175] According to the polyimide film of the present invention (in the laminated film of the present invention), even with a relatively small (thin, low proportion) metal layer, sufficient adhesion can be achieved.

[0176] In a laminated film, the thickness ratio of the polyimide film to the metal layer can be selected according to the application, etc. For example, the polyimide film / metal layer (thickness ratio) may be selected from a range of about 1 / 0.001 to 1 / 100 (e.g., 1 / 0.01 to 1 / 50), preferably 1 / 0.02 to 1 / 10 (e.g., 1 / 0.03 to 1 / 8), preferably 1 / 0.05 to 1 / 5 (e.g., 1 / 0.07 to 1 / 3), and even more preferably 1 / 0.1 to 1 / 2 (e.g., 1 / 0.15 to 1 / 1, 1 / 0.2 to 1 / 0.8). According to the polyimide film of the present invention (in the laminated film of the present invention), even with such a thickness ratio, the polyimide film can fully exhibit its function as a base film.

[0177] Taking copper laminated films (for example, copper laminated films suitable for printed circuit boards, etc.) as an example, a more specific example of a manufacturing method is to form a thin copper film on the surface of a polyimide film where copper will be formed, by surface treatment under vacuum conditions (for example, surface treatment with nickel / chromium by sputtering, followed by sputtering with copper), and then laminating the copper layer by electroplating using a copper sulfate bath or the like.

[0178] Furthermore, the metal layer (such as a copper plating layer) may be patterned by etching or other methods. The etching method is not particularly limited, and conventionally known methods may be used.

[0179] In a laminated film, the metal layer and the polyimide film may be firmly adhered to each other.

[0180] Examples of such laminated films include those having a peel strength (adhesion, tear strength) value (T1) between the metal layer and the polyimide film of more than 0.3 kN / m (for example, 0.35 kN / m or more), preferably 0.4 kN / m or more (for example, 0.45 kN / m or more), and more preferably 0.5 kN / m or more.

[0181] The upper limit of T1 is not particularly limited, but may be, for example, 5kN / m or less, 4kN / m or less, 3kN / m or less, 2.5kN / m or less, 2kN / m or less, 1.5kN / m or less, 1.2kN / m or less, 1kN / m or less, etc.

[0182] Such adhesion can be maintained at a relatively high level even when subjected to conditions such as high temperatures (e.g., harsh conditions). Examples of such laminated films include those in which, when T1 is the peel strength (adhesion, peel strength) between the metal layer and the polyimide film, and T2 is the peel strength (adhesion, peel strength) between the metal layer and the polyimide film after heating at 150°C for 168 hours, T2 / T1 is 0.3 or more (e.g., 0.4 or more), preferably 0.5 or more (e.g., greater than 0.5, 0.55 or more), more preferably 0.6 or more (e.g., 0.65 or more), particularly 0.7 or more (e.g., 0.72 or more), and particularly preferably 0.75 or more (e.g., greater than 0.75, 0.78 or more, 0.8 or more).

[0183] Note that the upper limit of T2 / T1 may be 1, or it may be less than 1 (for example, 0.99 or less, 0.98 or less, 0.97 or less, 0.96 or less, 0.95 or less, 0.94 or less, 0.93 or less, 0.92 or less, 0.91 or less, 0.9 or less).

[0184] Furthermore, the value of T2 may be, for example, greater than 0.2 kN / m (for example, 0.25 kN / m or more), preferably 0.3 kN / m or more (for example, 0.35 kN / m or more), and even more preferably 0.4 kN / m or more.

[0185] The upper limit of T2 is not particularly limited, but may be, for example, 5kN / m or less, 4kN / m or less, 3kN / m or less, 2.5kN / m or less, 2kN / m or less, 1.5kN / m or less, 1.2kN / m or less, 1kN / m or less, 0.9kN / m or less, 0.8kN / m or less, etc.

[0186] The measurement method for T1 (and even T2) may be, for example, one that conforms to Method A in the test method for the peel strength of copper foil described in JIS C 6471 (e.g., tensile angle 90°, tensile speed 50 mm / min). More specifically, T1 (and even T2) may be measured by the method described in the examples below.

[0187] Laminated films can be used in a variety of applications, such as COF (Chip on Film) and circuit boards (especially boards using fine-pitch wiring circuits) such as flexible printed circuit boards (FPCs). [Examples]

[0188] Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited in any way by these examples, and many modifications are possible within the technical concept of the present invention by those with ordinary skill in the art.

[0189] In the examples, the following compounds will be referred to by the following abbreviations. Paraphenylenediamine: PPD 4,4'-Diaminodiphenyl ether:4,4'-ODA Pyromellitic dianhydride: PMDA 3,3',4,4'-Biphenyltetracarboxylic acid dianhydride:BPDA N,N-dimethylacetamide:DMAc

[0190] Each characteristic was evaluated using the following method.

[0191] • Coefficient of thermal expansion (CTE) The measurement was performed using a TMA-50 (product name, manufactured by Shimadzu Corporation) under the following conditions: measurement temperature range: 50~200°C, heating rate: 10°C / min. The thermal expansion coefficient α was defined as α = (|αMD| + |αTD|) / 2, using the linear expansion coefficient αMD in the mechanical transport direction (MD) and the linear expansion coefficient αTD in the width direction (TD).

[0192] • Glass transition temperature (Tg) Instrument: A DMS6100 (product name: Hitachi High-Tech Science) was used, and measurements were taken in the temperature range of 25 to 420°C while infusing 50 mL / min of nitrogen at a heating rate of 2°C / min and a measurement frequency of 5 Hz. The temperature at which the loss tangent tanδ(E'' / E'), which is the ratio of the loss modulus (E'') to the storage modulus (E'), showed a maximum was defined as the glass transition temperature (Tg).

[0193] • Adhesion strength (90° peel strength) between copper and polyimide laminated film The adhesion strength between copper and polyimide laminated film was evaluated according to Method A of the test method for peel strength of copper foil described in JIS C 6471, measured under conditions of a tensile angle of 90° and a tensile speed of 50 mm / min. The adhesion strength measured immediately after fabrication of the copper-laminated polyimide film was defined as the normal adhesion strength (T1), and the adhesion strength measured after heating at 150°C for 168 hours was defined as the heat-resistant adhesion strength (T2).

[0194] • Thickness of the polyimide film (to which the coupling agent will be applied) Using a Mitutoyo Lightmatic (Series 318) thickness gauge, 15 points were arbitrarily selected from the entire surface of the film, the thickness of these 15 points was measured, and the average of these measurements was calculated to determine the film thickness.

[0195] • Thickness of layer (1) Using an ULVAC-FI X-ray photoelectron spectrometer, the Si intensity was measured in the depth direction from the film surface. The point where the slope of the relationship between Si intensity and depth (linear graph) changes was defined as the displacement point, and the depth from the film surface to this displacement point was defined as the thickness of layer (1).

[0196] • Thickness of layer (2) Using an ULVAC-PHI secondary ion mass spectrometer, the Si intensity was measured in the depth direction from the film surface, and the thickness of layer (2) was defined as the depth from the displacement point to where the Si intensity became 0.

[0197] • Evaluation of inorganic particles Using a LA-910 laser diffraction / scattering particle size distribution analyzer manufactured by Horiba, Ltd., samples dispersed in a polar solvent were measured, and the average particle size was read as the volume-average diameter from the analysis of the laser diffraction and scattered light intensity patterns.

[0198] • Measurement of dielectric breakdown voltage Measurements were taken in accordance with the flat-plate electrode method of JIS C 2151, with an input voltage of 100V ±10% at 50 / 60Hz, an output voltage of DC 0 to +50KV / 5mA, and a variable boost time of 40 to 800 seconds. The film test pieces were dried at 200°C for 30 minutes before measurement. The dimensions of the film test specimen were 200mm x 200mm, and the measurement atmosphere was 25℃ x 60%RH.

[0199] (Preparation of polyamic acid solution) [Synthesis Example 1] 25.7 g of PPD was placed in a 2000 mL separable flask, and 960 g of DMAc was added. The mixture was stirred until completely dissolved. Subsequently, 50.2 g of PMDA was added, and the mixture was stirred for 1 hour. Then, 71.3 g of 4,4'-ODA was added, and after confirming that it was completely dissolved, 52.4 g of BPDA and 39.1 g of PMDA were added, and the mixture was stirred for 3 hours to obtain a 3000 poise polyamic acid solution (20% solids by mass). To this, a silica DMAc slurry with an average particle size of 0.3 μm was added at a concentration of 0.3% by mass per weight of the polyamic acid resin, and the mixture was thoroughly stirred and dispersed.

[0200] (Preparation of coating solution) The coating solution (silane coupling agent-containing solution) was prepared as follows. [Coating liquid 1] Coating solution 1 was prepared by mixing 90 parts by mass of ethyl lactate (Musashino Scientific Research Institute), 10 parts by mass of ethanol, and 1 part by mass of 3-aminopropyltrimethoxysilane (Tokyo Chemical Industry Co., Ltd.). [Coating liquid 2] Coating solution 2 was prepared by mixing 90 parts by mass of ethyl lactate (Musashino Scientific Research Institute), 10 parts by mass of ethanol, and 2 parts by mass of 3-aminopropyltrimethoxysilane (Tokyo Chemical Industry Co., Ltd.). [Coating Liquid 3] Coating solution 3 was prepared by mixing 90 parts by mass of ethyl lactate (Musashino Scientific Research Institute), 10 parts by mass of ethanol, and 3 parts by mass of 3-aminopropyltrimethoxysilane (Tokyo Chemical Industry Co., Ltd.).

[0201] [Example 1] (Preparation of polyimide film) After cooling the polyamic acid solution obtained in Synthesis Example 1 to -5°C, a mixture was obtained by mixing 21 parts by mass of DMAc, 16 parts by mass of acetic anhydride, and 14 parts by mass of 3-methylpyridine with 100 parts by mass of solids of polyamic acid. This mixture was passed through a rotating drum at 85°C for 30 seconds using a T-type slit die. The resulting self-supporting film was then heated at 100°C for 5 minutes while being stretched 1.23 times in the running direction. Next, both ends in the width direction were grasped, and the film was stretched 1.4 times in the width direction while being heated at 270°C for 2 minutes. Finally, it was heated at 380°C for 90 seconds to obtain a polyimide film with a width of 500 mm, a thickness of 25 μm, and a length of 500 m. The coating solution 1 was applied to one side of the polyimide film, and the polyimide film 1 was dried at 130°C for 60 seconds. In the polyimide film 1, the thickness of layer (1) was 20 nm, and the thickness of layer (2) was 180 nm.

[0202] (Fabrication of copper-laminated polyimide films) One side of polyimide film 1 was plasma-treated, and then a 25 nm thick nickel / chromium alloy (nickel / chromium = 80 / 20) layer was formed by sputtering. Next, a 100 nm thick copper layer was formed on this nickel / chromium alloy layer, also by sputtering. Then, the copper layer thickness was reduced to 8.5 μm by electrolytic copper plating. Finally, a copper laminated polyimide film 1 was obtained by copper etching to pattern the film so that the wiring width was 1 mm. The adhesion strength of this copper-laminated polyimide film 1 was evaluated. The results are shown in Table 1.

[0203] [Example 2] Polyimide film 2 was obtained in the same manner as in Example 1, except that the drying temperature after application of the coating solution was 200°C. Furthermore, using this polyimide film 2, copper laminated polyimide film 2 was obtained in the same manner as in Example 1. The adhesion strength of this copper-laminated polyimide film 2 was evaluated. The results are shown in Table 1.

[0204] [Example 3] A polyimide film 3 was obtained in the same manner as in Example 1, except that the drying time after application of the coating solution was 90 seconds. Furthermore, a copper-laminated polyimide film 3 was obtained using this polyimide film 3 in the same manner as in Example 1. The adhesion strength of this copper-laminated polyimide film 3 was evaluated. The results are shown in Table 1.

[0205] [Example 4] A polyimide film 4 was obtained in the same manner as in Example 3, except that coating solution 2 was used instead of coating solution 1. Furthermore, a copper-laminated polyimide film 4 was obtained using this polyimide film 4 in the same manner as in Example 1. The adhesion strength of this copper-laminated polyimide film 4 was evaluated. The results are shown in Table 1.

[0206] [Example 5] A polyimide film 5 was obtained in the same manner as in Example 3, except that coating solution 3 was used instead of coating solution 1. Furthermore, a copper-laminated polyimide film 5 was obtained using this polyimide film 5 in the same manner as in Example 1. The adhesion strength of this copper-laminated polyimide film 5 was evaluated. The results are shown in Table 1.

[0207] [Comparative Example 1] A polyimide film 6 was obtained in the same manner as in Example 1, except that the coating solution of Example 1 was not applied. Furthermore, a copper-laminated polyimide film 6 was obtained using this polyimide film 6 in the same manner as in Example 1. The adhesion strength of this copper-laminated polyimide film 6 was evaluated. The results are shown in Table 1.

[0208] [Comparative Example 2] After cooling the polyamic acid solution obtained in Synthesis Example 1 to -5°C, a mixture was obtained by mixing 21 parts by mass of DMAc, 16 parts by mass of acetic anhydride, and 14 parts by mass of 3-methylpyridine with 100 parts by mass of solids of polyamic acid. This mixture was passed through a rotating drum at 85°C for 30 seconds using a T-type slit die. Then, coating liquid 3 was applied to one side of the resulting self-supporting film and dried at 120°C for 150 seconds. Next, it was stretched 1.23 times in the running direction while heating at 100°C for 5 minutes. Then, both ends in the width direction were grasped and it was stretched 1.4 times in the width direction while heating at 270°C for 2 minutes, and then heated at 380°C for 90 seconds to obtain a polyimide film 7 with a width of 500 mm, a thickness of 25 μm, and a length of 500 m. Furthermore, regarding the polyimide film 7, the Si intensity was measured in the depth direction from the film surface using an ULVAC-FI secondary ion mass spectrometer, similar to the method for measuring the thickness of layer (2) described above. The depth at which the Si intensity became 0 was measured and found to be 390 nm. Using polyimide film 7, a copper-laminated polyimide film 7 was obtained using the same procedure as in Example 1. The adhesion strength of this copper-laminated polyimide film 7 was evaluated. The results are shown in Table 1.

[0209] Note that in Table 1, αMD, αTD, α, Tg, and dielectric breakdown voltage are the values ​​for polyimide films 1 to 7.

[0210] [Table 1]

[0211] As shown in Table 1, the polyimide films of Examples 1 to 5 maintained better adhesion to the metal layer when exposed to high-temperature conditions compared to Comparative Examples 1 and 2. Furthermore, the polyimide films of Examples 1 to 5 showed higher dielectric breakdown voltages compared to Comparative Examples 1 and 2.

[0212] [Example 6] A polyimide film 8 was obtained in the same manner as in Example 1, except that the drying temperature after application of the coating solution was 170°C. Furthermore, a copper-laminated polyimide film 8 was obtained using this polyimide film 8 in the same procedure as in Example 1. The adhesion strength of this copper-laminated polyimide film 8 was evaluated. The results are shown in Table 2.

[0213] [Example 7] A polyimide film 9 was obtained in the same manner as in Example 1, except that the drying temperature after application of the coating solution was 250°C. Furthermore, a copper-laminated polyimide film 9 was obtained using this polyimide film 9 in the same procedure as in Example 1. The adhesion strength of this copper-laminated polyimide film 9 was evaluated. The results are shown in Table 2.

[0214] [Example 8] A polyimide film 10 was obtained in the same manner as in Example 1, except that the drying temperature after application of the coating solution was 280°C. Furthermore, a copper-laminated polyimide film 10 was obtained using this polyimide film 10 in the same manner as in Example 1. The adhesion strength of this copper-laminated polyimide film 10 was evaluated. The results are shown in Table 2.

[0215] [Table 2] [Industrial applicability]

[0216] The polyimide film of the present invention is useful for applications such as metal lamination.

Claims

1. The polyimide film has a layer (A) containing a hydrolysis condensate of a coupling agent on one or both sides, and the polyimide constituting the polyimide film has an aromatic diamine component and an aromatic acid anhydride component as polymerization components, and the polymerization components do not contain any polymerization components other than the aromatic acid anhydride component and the aromatic diamine component, or the proportion of polymerization components other than the aromatic acid anhydride component and the aromatic diamine component to the total polymerization components is 20 mol% or less. Layer (A) comprises a layer (1) which is substantially composed solely of hydrolyzed condensates of a coupling agent, and a layer (2) which contains hydrolyzed condensates of a coupling agent and components derived from polyimide. A polyimide film for metal lamination in which layer (A) is formed in the order of layer (2) and layer (1) from the surface side of the polyimide film, with a thickness of layer (1) of 5 nm or more and a thickness of layer (A) of 100 to 400 nm.

2. The polyimide film according to claim 1, wherein when the peel strength between the copper layer and the polyimide film when the copper layer is directly laminated is T1, and the peel strength between the copper layer and the polyimide film after heating at 150°C for 168 hours is T2, T1 is 0.4 kN / m or more, and T2 / T1 is 0.7 or more.

3. The polyimide film according to claim 1, wherein the coupling agent has an amino group.

4. The polyimide film according to claim 1 or 3, wherein the coupling agent comprises a silane coupling agent.

5. The polyimide film according to claim 1 or 3, wherein the coupling agent comprises an amino-based silane coupling agent.

6. The polyimide film according to claim 1, wherein the thickness of layer (2) is 300 nm or less.

7. The polyimide film according to claim 1 or 3, wherein the coupling agent comprises 3-aminopropyltrimethoxysilane.

8. The polyimide film according to claim 1 or 2, wherein when the linear expansion coefficient in the mechanical transport direction of the film is αMD and the linear expansion coefficient in the width direction is αTD, the value of (|αMD| + |αTD|) / 2 is 15 ppm / K or less.

9. A polyimide film according to claim 1 or 2, wherein the αTD is -5 to +10 ppm / K.

10. A polyimide film according to claim 1 or 2, wherein the polymerization components include an aromatic diamine component comprising at least one selected from paraphenylenediamine and 4,4'-diaminodiphenyl ether, and an aromatic acid anhydride component comprising at least one selected from pyromellitic dianhydride and 3,3',4,4'-biphenyltetracarboxylic acid dianhydride.

11. A polyimide film according to claim 1 or 2, containing inorganic particles.

12. A polyimide film according to claim 1 or 2, which is in the form of a roll.

13. The polyimide film according to claim 1 or 2, which contains inorganic particles in a proportion of 0.01 to 5% by mass and is in the form of a roll with a length of 5 m or more.

14. A polyimide film according to claim 1 or 2, for use in metallizing.

15. A polyimide film according to claim 1 or 2 for directly laminating a copper layer with a thickness of 20 μm or less.

16. The polyimide film according to claim 1 or 2, wherein the glass transition temperature is 285°C or higher.

17. A laminated film comprising a polyimide film and a metal layer directly laminated on the film, wherein the polyimide film is the polyimide film described in claim 1 or 2.

18. The laminated film according to claim 17, wherein the metal layer is a copper layer with a thickness of 20 μm or less.

19. The laminated film according to claim 17, wherein the peel strength T1 between the metal layer and the polyimide film is 0.5 kN / m or more.

20. The laminated film according to claim 17, wherein when T1 is the peel strength between the metal layer and the polyimide film, and T2 is the peel strength between the metal layer and the polyimide film after heating at 150°C for 168 hours, T1 is 0.4 kN / m or more, and T2 / T1 is 0.7 or more.

21. A method for producing a polyimide film for metal lamination, comprising the step of applying a coupling agent-containing solution to one or both sides of a polyimide film and then drying it, A method for producing a polyimide film, wherein the polyimide film has a layer (A) on one or both sides containing a hydrolysis condensate of a coupling agent, the polyimide constituting the polyimide film has an aromatic diamine component and an aromatic acid anhydride component as polymerization components, the polymerization components do not contain other polymerization components other than the aromatic acid anhydride component and the aromatic diamine component, or the proportion of other polymerization components other than the aromatic acid anhydride component and the aromatic diamine component to the total polymerization components is 20 mol% or less, and layer (A) comprises a layer (1) substantially formed only of a hydrolysis condensate of a coupling agent and a layer (2) containing a hydrolysis condensate of a coupling agent and components derived from polyimide, the layers (A) are formed in the order of layer (2) and layer (1) from the surface side of the polyimide film, the thickness of layer (1) is 5 nm or more, and the thickness of layer (A) is 100 to 400 nm.

22. The manufacturing method according to claim 21, wherein the coupling agent-containing solution contains 0.1 to 5% by mass of the coupling agent.

23. The manufacturing method according to claim 21 or 22, wherein drying is performed at a drying temperature of 130 to 200°C and a drying time of 40 to 100 seconds.

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