Film, layered body, circuit board, layered circuit board, and method for producing layered circuit board

Abstract

Provided is a film comprising a layer A and a layer B disposed on at least one surface of layer A. The ratio of the elastic modulus EB at 160°C of layer B to the elastic modulus EA at 160°C of layer A is 1.0 × 10-6 or greater and the dielectric loss tangent is 0.005 or less. Also provided are uses for the film.

Description

Film, laminate, wiring board, laminated wiring board, and method for manufacturing laminated wiring board

[0001] The present disclosure relates to a film, a laminate, a wiring board, a laminated wiring board, and a method for manufacturing a laminated wiring board.

[0002] In recent years, the frequencies used in communication devices have tended to become very high. To suppress transmission loss in the high-frequency band, it is necessary to lower the relative permittivity and dielectric loss tangent of insulating materials used in circuit boards.

[0003] For example, International Publication No. 2016 / 170779 describes a method for producing a metal-clad laminate in which a metal sheet is bonded to at least one surface of a thermoplastic liquid crystal polymer film capable of forming an optically anisotropic molten phase, in which the thermoplastic liquid crystal polymer film and the metal sheet are bonded to form a laminate, and the laminate is subjected to a heat treatment that satisfies conditions (1) and (2). Condition (1) is a condition in which the heat treatment temperature is 1°C or more and less than 50°C above the melting point of the thermoplastic liquid crystal polymer film, and condition (2) is a condition in which the heat treatment time is 1 second or more and 10 minutes or less. Japanese Patent Application Laid-Open No. 2019-199612 describes a resin composition containing a styrene-based polymer, an inorganic filler, and a curing agent, wherein the styrene-based polymer is an acid-modified styrene-based polymer having a carboxyl group, the inorganic filler is silica and / or aluminum hydroxide, the particle size of the inorganic filler is 1 μm or less, the content of the inorganic filler is 20 to 80 parts by mass per 100 parts by mass of the styrene-based polymer, and the resin composition, in the form of a film having a thickness of 25 μm, satisfies specific formulas (A) and (B).

[0004] According to an embodiment of the present invention, a film having a low dielectric loss tangent and excellent step conformability is provided. Also, according to another embodiment of the present invention, a laminate, a wiring board, a laminated wiring board, and a method for manufacturing a laminated wiring board using the above film are provided.

[0005] The present disclosure includes the following aspects: <1> A laminated sheet including a layer A and a layer B disposed on at least one surface of the layer A, wherein the ratio of the modulus of elasticity EB of the layer B at 160°C to the modulus of elasticity EA of the layer A at 160°C is 1.0 x 10 －６or more and a dielectric dissipation factor of 0.005 or less. <2> The film according to <1>, wherein the elastic modulus EB is 0.1 GPa or less. <3> The film according to <1> or <2>, wherein the ratio of the elastic modulus EB to the elastic modulus EA is 0.1 or less. <4> The film according to any one of <1> to <3>, wherein the average thickness of Layer B is 15 μm or less. <5> The film according to any one of <1> to <4>, wherein Layer A contains a liquid crystal polymer. <6> The film according to any one of <1> to <5>, wherein Layer A has a melting point of 315°C or more. <7> The film according to any one of <1> to <6>, wherein Layer A contains a polyolefin. <8> The film according to <7>, wherein the content of the polyolefin is 5% by mass to 30% by mass, relative to the total mass of Layer A. <9> The film according to any one of <1> to <8>, wherein Layer B contains a cured product of a composition containing a polymer and a compound having a reactive group. <10> The film according to any one of <1> to <9>, further comprising a Layer C, and arranged in the order of Layer C, Layer A, and Layer B. <11> The film according to <10>, in which the average thickness of Layer C is 15 μm or less. <12> The film according to <10> or <11>, in which Layer C contains a cured product of a polymer and a compound having a reactive group. <13> A laminate comprising the film according to any one of <1> to <12> and a metal layer disposed on at least one surface of the film. <14> A wiring board comprising the film according to any one of <1> to <12>, metal wiring disposed on one surface of the film, and a metal layer disposed on the other surface of the film. <15> A laminated wiring board having, in this order: a first metal layer, a first film according to any one of <1> to <12>, metal wiring, a second film according to any one of <1> to <12>, and a second metal layer, wherein the metal wiring is embedded in a part of the first film and the second film.<16> A method for producing a laminated wiring board, comprising: a step of producing a laminate having the first film according to any one of <1> to <12> and a first metal layer disposed on one surface of the first film; a step of producing a wiring board having the second film according to any one of <1> to <12>, metal wiring disposed on one surface of the second film, and a second metal layer disposed on the other surface of the second film; and a step of superposing the laminate and the wiring board so that the first metal layer and the second metal layer are both outermost surfaces, and thermocompression bonding them.

[0006] According to an embodiment of the present invention, a film having a low dielectric loss tangent and excellent step conformability is provided. Also, according to another embodiment of the present invention, a laminate, a wiring board, a laminated wiring board, and a method for manufacturing a laminated wiring board using the above film are provided.

[0007] The contents of the present disclosure will be described in detail below. The following description of the constituent elements may be based on representative embodiments of the present disclosure, but the present disclosure is not limited to such embodiments. In the present disclosure, the term "to" indicating a numerical range is used to mean that the numerical values ​​before and after it are included as the upper and lower limits. In the numerical ranges described in stages in the present disclosure, the upper or lower limit described in one numerical range may be replaced with the upper or lower limit of another numerical range described in stages. Furthermore, in the numerical ranges described in the present disclosure, the upper or lower limit of that numerical range may be replaced with a value shown in the examples. Furthermore, in the notation of groups (atomic groups) in the present disclosure, notations that do not specify whether they are substituted or unsubstituted include both unsubstituted and substituted groups. For example, the term "alkyl group" includes not only alkyl groups without substituents (unsubstituted alkyl groups) but also alkyl groups with substituents (substituted alkyl groups). In the present disclosure, "(meth)acrylic" is a term used as a concept encompassing both acrylic and methacrylic, and "(meth)acryloyl" is a term used as a concept encompassing both acryloyl and methacryloyl. Furthermore, the term "process" in the present disclosure includes not only an independent process but also a process that cannot be clearly distinguished from other processes, as long as the intended purpose of the process is achieved. Furthermore, in the present disclosure, "mass %" and "wt %" are synonymous, and "parts by mass" and "parts by weight" are synonymous. Furthermore, in the present disclosure, a combination of two or more preferred embodiments is a more preferred embodiment. Furthermore, unless otherwise specified, the weight average molecular weight (Mw) and number average molecular weight (Mn) in the present disclosure are molecular weights calculated using a gel permeation chromatography (GPC) analyzer equipped with a column of TSKgel Super HM-H (trade name of Tosoh Corporation), using a solvent of PFP (pentafluorophenol) / chloroform = 1 / 2 (mass ratio) and a differential refractometer, and converted using polystyrene as a standard substance.

[0008] In the present disclosure, when the film is long, the width direction means the short direction and TD (transverse direction) of the film, and the length direction means the longitudinal direction and MD (machine direction) of the film material.

[0009] [Film] The film according to the present disclosure includes a layer A and a layer B disposed on at least one surface of the layer A, and the ratio of the elastic modulus EB of the layer B at 160°C to the elastic modulus EA of the layer A at 160°C is 1.0 x 10 －６ or more, and the dielectric loss tangent is 0.005 or less.

[0010] As a result of intensive research, the present inventors have found that the above-described configuration can provide a film with excellent conformability to unevenness. Note that, in the present disclosure, "conformability to unevenness" refers to the property of easily deforming to conform to unevenness and easily retaining the shape after deformation.

[0011] In the film according to the present disclosure, the ratio of the elastic modulus EB of Layer B at 160°C to the elastic modulus EA of Layer A at 160°C is 1.0 x 10 －６ For the above reasons, Layer B is not too soft. Therefore, for example, when the film is bonded to a metal wiring on a wiring board, the film deforms to conform to the steps of the metal wiring and is maintained in the deformed state. In other words, the film according to the present disclosure has excellent step conformability.

[0012] On the other hand, the thermoplastic liquid crystal polymer film described in WO 2016 / 170779 needs to be heated at a high temperature to deform, and the thermoplastic liquid crystal polymer flows when heated at a high temperature, making it difficult to maintain the deformed state of the film. Furthermore, JP 2019-199612 A does not mention the ability to conform to unevenness.

[0013] <Ratio of Elastic Modulus EB of Layer B at 160°C to Elastic Modulus EA of Layer A at 160°C> In the film according to the present disclosure, the ratio of Elastic Modulus EB of Layer B at 160°C to Elastic Modulus EA of Layer A at 160°C (i.e., Elastic Modulus EB / Elastic Modulus EA) is 1.0×10 －６ The above ratio is 1.0 × 10－６ When the ratio is 1.0×10 or more, Layer B is not too soft and has excellent conformability to unevenness. －４ It is preferable that the ratio is 1.0×10 or more. －３ More preferably, it is equal to or greater than this.

[0014] Furthermore, from the viewpoint of further improving the step-conforming ability, the ratio is preferably 0.1 or less, more preferably 0.05 or less, and even more preferably 0.01 or less.

[0015] The elastic modulus in the present disclosure is measured by the following method. The elastic modulus at 160°C of Layer A and Layer B constituting the laminate is the indentation elastic modulus determined by measuring the elastic modulus of each layer in a cross section obtained by cutting the laminate along the thickness direction using a nanoindenter in a temperature environment of 160°C in accordance with the method described in ISO 14577. Specific methods for measuring the elastic modulus of each layer are described in the examples below.

[0016] <Dielectric Loss Tangent> From the viewpoint of reducing transmission loss, the film according to the present disclosure has a dielectric loss tangent of 0.005 or less, preferably 0.002 or less, and more preferably greater than 0 and 0.001 or less.

[0017] In the present disclosure, the dielectric loss tangent is measured by the following method. The dielectric loss tangent is measured at a frequency of 10 GHz by the resonance perturbation method. A 10 GHz cavity resonator (Kanto Electronics Application Development Co., Ltd. CP531) is connected to a network analyzer (Agilent Technology Corporation "E8363B"), and a measurement sample (width: 2.0 mm x length: 80 mm) is inserted into the cavity resonator. The dielectric loss tangent of the measurement sample is measured from the change in resonance frequency before and after insertion for 96 hours in an environment of 25°C temperature and 60% RH.

[0018] <Layer A> The film according to the present disclosure has Layer A. The following methods can be used to detect or determine the layer structure and the thickness of each layer in the film. First, a cross-sectional sample of the film is cut out using a microtome, and the layer structure and the thickness of each layer are determined using an optical microscope. If determination using an optical microscope is difficult, the layer structure and the thickness of each layer may be determined by morphological observation using a scanning electron microscope (SEM) or by component analysis using time-of-flight secondary ion mass spectrometry (TOF-SIMS) or the like.

[0019] The elastic modulus EA of Layer A at 160°C is preferably 2.0 GPa or less, more preferably 1.0 GPa or less. When the elastic modulus EA of Layer A at 160°C is small, Layer A can deform along with Layer B to conform to the step, improving the conformability of the entire film to the step. The lower limit of the elastic modulus EA is not particularly limited, and is, for example, 0.1 GPa.

[0020] From the viewpoint of suitability for wiring processability and lamination processability, the melting point of Layer A is preferably 315° C. or higher, and more preferably 320° C. or higher. The upper limit of the melting point is not particularly limited, and is, for example, 380° C.

[0021] In this disclosure, melting points are measured using a differential scanning calorimeter.

[0022] From the viewpoint of transmission loss of the film, the dielectric loss tangent of Layer A is preferably 0.004 or less, more preferably 0.002 or less, even more preferably 0.0015 or less, and particularly preferably greater than 0 to 0.001.

[0023] The components constituting Layer A are not particularly limited as long as the elastic modulus EA and the elastic modulus EB satisfy the above ratio. Layer A preferably contains at least one polymer because it is easier to satisfy the above ratio.

[0024] The type of polymer is not particularly limited, and known polymers can be used.

[0025] Examples of the polymer include thermoplastic resins such as liquid crystal polymers, fluororesins, polymers of compounds having a cyclic aliphatic hydrocarbon group and a group having an ethylenically unsaturated bond, polyether ether ketone, polyolefin, polyamide, polyester, polyphenylene sulfide, polyether ketone, polycarbonate, polyether sulfone, polyphenylene ether and modified products thereof, and polyether imide; elastomers such as copolymers of glycidyl methacrylate and polyethylene; and thermosetting resins such as phenol resins, epoxy resins, polyimides, and cyanate resins.

[0026] Among these, from the viewpoint of reducing the dielectric loss tangent of the film, Layer A preferably contains at least one polymer selected from the group consisting of a liquid crystal polymer, a fluororesin, a polymer of a compound having a cyclic aliphatic hydrocarbon group and a group having an ethylenically unsaturated bond, and polyphenylene ether, and more preferably contains at least one polymer selected from the group consisting of a liquid crystal polymer and a fluororesin. From the viewpoint of film formability and mechanical strength, it is particularly preferable to contain a liquid crystal polymer, and from the viewpoint of dielectric loss tangent, it is particularly preferable to contain a fluororesin.

[0027] - Liquid Crystal Polymer - The type of liquid crystal polymer is not particularly limited, and known liquid crystal polymers can be used. The liquid crystal polymer may be a thermotropic liquid crystal polymer that exhibits liquid crystallinity in a molten state, or a lyotropic liquid crystal polymer that exhibits liquid crystallinity in a solution state. In the case of a thermotropic liquid crystal, it is preferable that the polymer melts at a temperature of 450°C or less.

[0028] Examples of liquid crystal polymers include liquid crystal polyester, liquid crystal polyester amide in which an amide bond is introduced into liquid crystal polyester, liquid crystal polyester ether in which an ether bond is introduced into liquid crystal polyester, and liquid crystal polyester carbonate in which a carbonate bond is introduced into liquid crystal polyester.

[0029] From the viewpoint of liquid crystallinity, the liquid crystal polymer is preferably a polymer having an aromatic ring, and more preferably an aromatic polyester or an aromatic polyester amide.

[0030] Furthermore, the liquid crystal polymer may be a polymer in which an isocyanate-derived bond such as an imide bond, a carbodiimide bond, or an isocyanurate bond is further introduced into an aromatic polyester or an aromatic polyester amide.

[0031] The liquid crystal polymer is preferably a wholly aromatic liquid crystal polymer made using only aromatic compounds as raw material monomers.

[0032] Examples of liquid crystal polymers include the following: 1) A liquid crystal polymer obtained by polycondensation of (i) an aromatic hydroxycarboxylic acid, (ii) an aromatic dicarboxylic acid, and (iii) at least one compound selected from the group consisting of an aromatic diol, an aromatic hydroxyamine, and an aromatic diamine; 2) A liquid crystal polymer obtained by polycondensation of multiple aromatic hydroxycarboxylic acids; 3) A liquid crystal polymer obtained by polycondensation of (i) an aromatic dicarboxylic acid and (ii) at least one compound selected from the group consisting of an aromatic diol, an aromatic hydroxyamine, and an aromatic diamine; 4) A liquid crystal polymer obtained by polycondensation of (i) a polyester such as polyethylene terephthalate and (ii) an aromatic hydroxycarboxylic acid. Here, the aromatic hydroxycarboxylic acid, aromatic dicarboxylic acid, aromatic diol, aromatic hydroxyamine, and aromatic diamine may each independently be replaced with a derivative capable of polycondensation.

[0033] For example, aromatic hydroxycarboxylic acids and aromatic dicarboxylic acids can be replaced with aromatic hydroxycarboxylic acid esters and aromatic dicarboxylic acid esters by converting the carboxy group to an alkoxycarbonyl group or an aryloxycarbonyl group. Aromatic hydroxycarboxylic acids and aromatic dicarboxylic acids can be replaced with aromatic hydroxycarboxylic acid halides and aromatic dicarboxylic acid halides by converting the carboxy group to a haloformyl group. Aromatic hydroxycarboxylic acids and aromatic dicarboxylic acids can be replaced with aromatic hydroxycarboxylic acid anhydrides and aromatic dicarboxylic acid anhydrides by converting the carboxy group to an acyloxycarbonyl group. Examples of polymerizable derivatives of compounds having a hydroxy group, such as aromatic hydroxycarboxylic acids, aromatic diols, and aromatic hydroxyamines, include those obtained by acylation of the hydroxy group to an acyloxy group (acylated products). For example, aromatic hydroxycarboxylic acids, aromatic diols, and aromatic hydroxyamines can be replaced with acylated products by acylation of the hydroxy group to an acyloxy group. Examples of polymerizable derivatives of compounds having an amino group, such as aromatic hydroxyamines and aromatic diamines, include those obtained by acylation of the amino group to an acylamino group (acylated products). For example, aromatic hydroxyamines and aromatic diamines can be substituted with their acylated products by acylation of the amino groups to convert them into acylamino groups.

[0034] The liquid crystal polymer is preferably a polymer having crystallinity (for example, aromatic polyester amide described below). When the liquid crystal polymer has crystallinity, the dielectric loss tangent becomes smaller.

[0035] The melting point of the liquid crystal polymer is preferably 250°C or higher, more preferably 250°C to 350°C, and even more preferably 260°C to 330°C.

[0036] The weight average molecular weight of the liquid crystal polymer is preferably 1,000,000 or less, more preferably 3,000 to 300,000, even more preferably 5,000 to 100,000, and particularly preferably 5,000 to 30,000.

[0037] From the viewpoint of further reducing the dielectric loss tangent, the liquid crystal polymer preferably contains an aromatic polyesteramide. The aromatic polyesteramide is a resin having at least one aromatic ring and having an ester bond and an amide bond. In particular, from the viewpoint of heat resistance, the aromatic polyesteramide contained in the resin layer is preferably a wholly aromatic polyesteramide.

[0038] The aromatic polyester amide preferably contains a structural unit represented by the following formula 1, a structural unit represented by the following formula 2, and a structural unit represented by the following formula 3: １ -CO-...Formula 1 -CO-Ar ２ -CO-...Formula 2 -NH-Ar ３ -O-...Formula 3 In Formulas 1 to 3, Ar １ , Ar ２ , and Ar ３ each independently represents a phenylene group, a naphthylene group, or a biphenylylene group. Hereinafter, the structural unit represented by formula 1 may also be referred to as "unit 1", etc.

[0039] Unit 1 can be introduced, for example, by using an aromatic hydroxycarboxylic acid as a raw material. Unit 2 can be introduced, for example, by using an aromatic dicarboxylic acid as a raw material. Unit 3 can be introduced, for example, by using an aromatic hydroxylamine as a raw material.

[0040] Here, the aromatic hydroxycarboxylic acid, aromatic dicarboxylic acid, aromatic diol, and aromatic hydroxylamine may each independently be replaced with a derivative capable of undergoing polycondensation.

[0041] For example, by converting the carboxy group to an alkoxycarbonyl group or an aryloxycarbonyl group, aromatic hydroxycarboxylic acids and aromatic dicarboxylic acids can be replaced with aromatic hydroxycarboxylic acid esters and aromatic dicarboxylic acid esters. By converting the carboxy group to a haloformyl group, aromatic hydroxycarboxylic acids and aromatic dicarboxylic acids can be replaced with aromatic hydroxycarboxylic acid halides and aromatic dicarboxylic acid halides. By converting the carboxy group to an acyloxycarbonyl group, aromatic hydroxycarboxylic acids and aromatic dicarboxylic acids can be replaced with aromatic hydroxycarboxylic acid anhydrides and aromatic dicarboxylic acid anhydrides. Examples of polycondensable derivatives of compounds having hydroxy groups, such as aromatic hydroxycarboxylic acids and aromatic hydroxyamines, include those obtained by acylation of the hydroxy group to an acyloxy group (acylated products). For example, by acylation of the hydroxy group to an acyloxy group, aromatic hydroxycarboxylic acids and aromatic hydroxylamines can be replaced with acylated products, respectively. Examples of polycondensable derivatives of aromatic hydroxylamines include those obtained by acylation of the amino group to an acylamino group (acylated products). For example, aromatic hydroxyamines can be replaced with acylated products by acylation of the amino group to convert them into acylamino groups.

[0042] In formula 1, Ar １ is preferably a p-phenylene group, a 2,6-naphthylene group, or a 4,4'-biphenylylene group, and more preferably a 2,6-naphthylene group.

[0043] Ar １ When Ar is a p-phenylene group, unit 1 is, for example, a constitutional unit derived from p-hydroxybenzoic acid. １ When Ar is a 2,6-naphthylene group, unit 1 is, for example, a structural unit derived from 6-hydroxy-2-naphthoic acid. １is a 4,4'-biphenylylene group, unit 1 is, for example, a constituent unit derived from 4'-hydroxy-4-biphenylcarboxylic acid.

[0044] In formula 2, Ar ２ is preferably a p-phenylene group, an m-phenylene group, or a 2,6-naphthylene group, and more preferably an m-phenylene group.

[0045] Ar ２ When Ar is a p-phenylene group, unit 2 is, for example, a structural unit derived from terephthalic acid. ２ When Ar is an m-phenylene group, unit 2 is, for example, a structural unit derived from isophthalic acid. ２ is a 2,6-naphthylene group, unit 2 is, for example, a structural unit derived from 2,6-naphthalenedicarboxylic acid.

[0046] In formula 3, Ar ３ is preferably a p-phenylene group or a 4,4'-biphenylylene group, and more preferably a p-phenylene group.

[0047] Ar ３ When Ar is a p-phenylene group, unit 3 is, for example, a constitutional unit derived from p-aminophenol. ３ is a 4,4'-biphenylylene group, unit 3 is, for example, a constitutional unit derived from 4-amino-4'-hydroxybiphenyl.

[0048] With respect to the total content of units 1, 2, and 3, the content of units 1 is preferably 30 mol% or more, the content of units 2 is preferably 35 mol% or less, and the content of units 3 is preferably 35 mol% or less. With respect to the total content of units 1, 2, and 3, the content of units 1 is more preferably 30 mol% to 80 mol%, even more preferably 30 mol% to 60 mol%, and particularly preferably 30 mol% to 40 mol%. With respect to the total content of units 1, 2, and 3, the content of units 2 is preferably 10 mol% to 35 mol%, even more preferably 20 mol% to 35 mol%, and particularly preferably 30 mol% to 35 mol%. With respect to the total content of units 1, 2, and 3, the content of units 3 is preferably 10 mol% to 35 mol%, even more preferably 20 mol% to 35 mol%, and particularly preferably 30 mol% to 35 mol%. The total content of each structural unit is the sum of the amounts (moles) of each structural unit, which is calculated by dividing the mass of each structural unit constituting the aromatic polyesteramide by the formula weight of the structural unit.

[0049] The ratio of the content of units 2 to the content of units 3, expressed as [content of units 2] / [content of units 3] (mol / mol), is preferably 0.9 / 1 to 1 / 0.9, more preferably 0.95 / 1 to 1 / 0.95, and even more preferably 0.98 / 1 to 1 / 0.98.

[0050] The aromatic polyesteramide may independently have two or more types of units 1 to 3. The aromatic polyesteramide may also have other structural units in addition to units 1 to 3. The content of other structural units is preferably 10 mol % or less, more preferably 5 mol % or less, based on the total content of all structural units.

[0051] The aromatic polyesteramide is preferably produced by melt-polymerizing raw material monomers corresponding to the structural units that constitute the aromatic polyesteramide.

[0052] Layer A may contain only one type of aromatic polyester amide, or may contain two or more types of aromatic polyester amide.

[0053] The content of the aromatic polyester amide is preferably 50% by mass or more, more preferably 70% by mass or more, and even more preferably 90% by mass or more, based on the total amount of Layer A. The upper limit of the content of the aromatic polyester amide is not particularly limited, and may be 100% by mass.

[0054] Liquid crystal polymers are preferably produced by melt-polymerizing raw material monomers corresponding to the structural units that constitute them. Melt polymerization may be carried out in the presence of a catalyst. Examples of this catalyst include metal compounds such as magnesium acetate, stannous acetate, tetrabutyl titanate, lead acetate, sodium acetate, potassium acetate, and antimony trioxide, and nitrogen-containing heterocyclic compounds such as 4-(dimethylamino)pyridine and 1-methylimidazole. Nitrogen-containing heterocyclic compounds are preferably used. Note that the melt polymerization may be further subjected to solid-state polymerization, if necessary.

[0055] The liquid crystal polymer has a flow initiation temperature of preferably 250° C. or higher, more preferably 250° C. or higher and 350° C. or lower, and even more preferably 260° C. or higher and 330° C. or lower. When the flow initiation temperature of the liquid crystal polymer is within the above range, the polymer has excellent solubility, heat resistance, strength, and rigidity, and the viscosity of the solution is appropriate.

[0056] The flow initiation temperature is also called the flow temperature or the flow temperature, and is measured using a capillary rheometer at a pressure of 9.8 MPa (100 kg / cm ２ When a liquid crystal polymer is melted and extruded through a nozzle having an inner diameter of 1 mm and a length of 10 mm while heating at a rate of 4°C / min under a load of 1000 kJ / cm2, the temperature rises to 4,800 Pa s (48,000 poise), and this temperature is used as a measure of the molecular weight of the liquid crystal polymer (see "Liquid Crystal Polymer - Synthesis, Molding, and Application" edited by Naoyuki Koide, CMC Co., Ltd., June 5, 1987, p. 95).

[0057] -Fluororesin- In the present disclosure, the type of fluororesin is not particularly limited, and known fluororesins can be used.

[0058] Fluorine resins include homopolymers and copolymers containing structural units derived from fluorinated α-olefin monomers, i.e., α-olefin monomers containing at least one fluorine atom, and copolymers containing structural units derived from fluorinated α-olefin monomers and structural units derived from non-fluorinated ethylenically unsaturated monomers reactive with the fluorinated α-olefin monomers.

[0059] Fluorinated α-olefin monomers include CF ２ =CF ２ , CHF=CF ２ , C.H. ２ =CF ２ , CHCl=CHF, CClF=CF ２ , CCl ２ =CF ２ , CClF=CClF, CHF=CCl ２ , C.H. ２ = CClF, CCl ２ = CClF, CF ３ CF = CF ２ , C.F. ３ CF = CHF, CF ３ CH=CF ２ , C.F. ３ CH=CH ２ , CHF ２ CH=CHF, CF ３ CF = CF ２ , and perfluoro(C2-C8 alkyl) vinyl ethers (e.g., perfluoromethyl vinyl ether, perfluoropropyl vinyl ether, and perfluorooctyl vinyl ether). Among these, the fluorinated α-olefin monomers include tetrafluoroethylene (CF ２ =CF ２ ), chlorotrifluoroethylene (CClF=CF ２ ), (perfluorobutyl)ethylene, vinylidene fluoride (CH ２ =CF ２ ), and hexafluoropropylene (CF ２ =CFCF ３) is preferably at least one monomer selected from the group consisting of: ethylene, propylene, butene, and ethylenically unsaturated aromatic monomers (for example, styrene and α-methylstyrene). The fluorinated α-olefin monomer may be used alone or in combination of two or more types. The non-fluorinated ethylenically unsaturated monomer may be used alone or in combination of two or more types.

[0060] Examples of fluororesins include polychlorotrifluoroethylene (PCTFE), poly(chlorotrifluoroethylene-propylene), poly(ethylene-tetrafluoroethylene) (ETFE), poly(ethylene-chlorotrifluoroethylene) (ECTFE), poly(hexafluoropropylene), poly(tetrafluoroethylene) (PTFE), poly(tetrafluoroethylene-ethylene-propylene), poly(tetrafluoroethylene-hexafluoropropylene) (FEP), poly(tetrafluoroethylene-propylene) (FEPM), poly(tetrafluoroethylene-perfluoropropylene vinyl ether), poly(tetrafluoroethylene-perfluoroalkyl vinyl ether) (PFA) (e.g., poly(tetrafluoroethylene-perfluoropropyl vinyl ether)), polyvinyl fluoride (PVF), polyvinylidene fluoride (PVDF), poly(vinylidene fluoride-chlorotrifluoroethylene), perfluoropolyether, perfluorosulfonic acid, and perfluoropolyoxetane.

[0061] The fluororesin may have a structural unit derived from fluorinated ethylene or fluorinated propylene. The fluororesin may be used alone or in combination of two or more types.

[0062] The fluororesin is preferably FEP, PFA, ETFE, or PTFE. FEP is available from DuPont under the trade name TEFLON FEP, or from Daikin Industries, Ltd. under the trade name NEOFLON FEP. PFA is available from Daikin Industries, Ltd. under the trade name NEOFLON PFA, from DuPont under the trade name TEFLON PFA, or from Solvay Solexis under the trade name HYFLON PFA.

[0063] The fluororesin more preferably contains PTFE. The PTFE may be a PTFE homopolymer, a partially modified PTFE homopolymer, or a combination containing one or both of these. The partially modified PTFE homopolymer preferably contains less than 1 mass% of structural units derived from comonomers other than tetrafluoroethylene, based on the total mass of the polymer.

[0064] The fluororesin may be a crosslinkable fluoropolymer having a crosslinkable group. The crosslinkable fluoropolymer can be crosslinked by a conventionally known crosslinking method. One of the representative crosslinkable fluoropolymers is a fluoropolymer having (meth)acryloyloxy. For example, the crosslinkable fluoropolymer is a fluoropolymer having the formula: H ２ C=CR'COO-(CH ２ ) ｎ -R-(CH ２ ) ｎ -OOCR'=CH ２ In this formula, R is an oligomer chain containing constitutional units derived from fluorinated α-olefin monomers, and R′ is H or —CH ３ and n is 1 to 4. R may be a fluorine-containing oligomer chain containing a structural unit derived from tetrafluoroethylene.

[0065] A crosslinked fluoropolymer network can be formed by exposing a fluoropolymer having (meth)acryloyloxy groups to a free radical source to initiate a radical crosslinking reaction via the (meth)acryloyloxy groups on the fluororesin. The free radical source is not particularly limited, but suitable examples include a photoradical polymerization initiator or an organic peroxide. Suitable photoradical polymerization initiators and organic peroxides are well known in the art. Crosslinkable fluoropolymers are commercially available, for example, Viton B manufactured by DuPont.

[0066] Polymer of a Compound Having a Cyclic Aliphatic Hydrocarbon Group and a Group Having an Ethylenically Unsaturated Bond Examples of polymers of compounds having a cycloaliphatic hydrocarbon group and a group having an ethylenically unsaturated bond include thermoplastic resins having structural units derived from cyclic olefin monomers such as norbornene or polycyclic norbornene monomers. Polymers of compounds having a cycloaliphatic hydrocarbon group and a group having an ethylenically unsaturated bond may be ring-opening polymers of the above-mentioned cyclic olefins or hydrogenated ring-opening copolymers using two or more cyclic olefins, or may be addition polymers of cyclic olefins and aromatic compounds having an ethylenically unsaturated bond such as linear olefins or vinyl groups. Furthermore, a polar group may be introduced into the polymer of a compound having a cycloaliphatic hydrocarbon group and a group having an ethylenically unsaturated bond. Polymers of compounds having a cycloaliphatic hydrocarbon group and a group having an ethylenically unsaturated bond may be used alone or in combination of two or more.

[0067] The ring structure of the cycloaliphatic hydrocarbon group may be a monocycle, a fused ring in which two or more rings are fused, or a bridged ring. Examples of the ring structure of the cycloaliphatic hydrocarbon group include a cyclopentane ring, a cyclohexane ring, a cyclooctane ring, an isoborone ring, a norbornane ring, and a dicyclopentane ring. The compound having a cycloaliphatic hydrocarbon group and a group having an ethylenically unsaturated bond is not particularly limited, and examples thereof include (meth)acrylate compounds having a cycloaliphatic hydrocarbon group, (meth)acrylamide compounds having a cycloaliphatic hydrocarbon group, and vinyl compounds having a cycloaliphatic hydrocarbon group. Among these, (meth)acrylate compounds having a cycloaliphatic hydrocarbon group are preferred. Furthermore, the compound having a cycloaliphatic hydrocarbon group and a group having an ethylenically unsaturated bond may be a monofunctional ethylenically unsaturated compound or a polyfunctional ethylenically unsaturated compound. The number of cycloaliphatic hydrocarbon groups in the compound having a cycloaliphatic hydrocarbon group and a group having an ethylenically unsaturated bond may be one or more, and may be two or more. The polymer of a compound having a cycloaliphatic hydrocarbon group and a group having an ethylenically unsaturated bond may be a polymer obtained by polymerizing at least one compound having a cycloaliphatic hydrocarbon group and a group having an ethylenically unsaturated bond, and may be a polymer of a compound having two or more types of cycloaliphatic hydrocarbon groups and a group having an ethylenically unsaturated bond, or may be a copolymer with another ethylenically unsaturated compound that does not have a cycloaliphatic hydrocarbon group. Furthermore, the polymer of a compound having a cycloaliphatic hydrocarbon group and a group having an ethylenically unsaturated bond is preferably a cycloolefin polymer.

[0068] -Polyphenylene Ether- From the viewpoints of dielectric dissipation factor and heat resistance, the average number of phenolic hydroxyl groups at the molecular terminals of the polyphenylene ether per molecule (number of terminal hydroxyl groups) is preferably 1 to 5, and more preferably 1.5 to 3. The number of terminal hydroxyl groups of the polyphenylene ether can be determined, for example, from the specification value of the polyphenylene ether product. The number of terminal hydroxyl groups is expressed, for example, as the average number of phenolic hydroxyl groups per molecule of all polyphenylene ethers present in 1 mole of the polyphenylene ether. One type of polyphenylene ether may be used alone, or two or more types may be used in combination.

[0069] Examples of polyphenylene ethers include polyphenylene ethers composed of 2,6-dimethylphenol and at least one of a bifunctional phenol and a trifunctional phenol, and poly(2,6-dimethyl-1,4-phenylene oxide). More specifically, the polyphenylene ether is preferably a compound having a structure represented by the formula (PPE).

[0070]

[0071] In formula (PPE), X represents an alkylene group having 1 to 3 carbon atoms or a single bond, m represents an integer of 0 to 20, n represents an integer of 0 to 20, and the sum of m and n represents an integer of 1 to 30. Examples of the alkylene group in X include a dimethylmethylene group.

[0072] When the polyphenylene ether is thermally cured after film formation, the weight average molecular weight (Mw) is preferably 500 to 5,000, and more preferably 500 to 3,000, from the viewpoints of heat resistance and film formability. When the polyphenylene ether is not thermally cured, the weight average molecular weight (Mw) is not particularly limited, but is preferably 3,000 to 100,000, and more preferably 5,000 to 50,000.

[0073] - Aromatic polyether ketone - The aromatic polyether ketone is not particularly limited, and known aromatic polyether ketones can be used. The aromatic polyether ketone is preferably polyether ether ketone. Polyether ether ketone is a type of aromatic polyether ketone, and is a polymer in which bonds are arranged in the following order: ether bond, ether bond, and carbonyl bond. The bonds are preferably connected by a divalent aromatic group. The aromatic polyether ketone may be used alone or in combination of two or more types.

[0074] Examples of aromatic polyether ketones include polyether ether ketone (PEEK) having a chemical structure represented by the following formula (P1), polyether ketone (PEK) having a chemical structure represented by the following formula (P2), polyether ketone ketone (PEKK) having a chemical structure represented by the following formula (P3), polyether ether ketone ketone (PEEKK) having a chemical structure represented by the following formula (P4), and polyether ketone ether ketone ketone (PEKEKK) having a chemical structure represented by the following formula (P5).

[0075]

[0076] In terms of mechanical properties, n in each of the formulae (P1) to (P5) is preferably 10 or greater, and more preferably 20 or greater. On the other hand, in terms of ease of production of the aromatic polyether ketone, n is preferably 5,000 or less, and more preferably 1,000 or less. That is, n is preferably 10 to 5,000, and more preferably 20 to 1,000.

[0077] As described above, Layer A preferably contains at least one liquid crystal polymer. When Layer A contains a liquid crystal polymer, the content of the liquid crystal polymer is preferably 20% by mass to 100% by mass, more preferably 50% by mass to 95% by mass, and particularly preferably 70% by mass to 90% by mass, relative to the total mass of Layer A, from the viewpoints of the dielectric loss tangent of the film and adhesion to the metal layer.

[0078] -Polyolefin- From the viewpoint of further reducing the dielectric loss tangent, it is preferable that Layer A further contains at least one polyolefin.

[0079] In the present disclosure, polyolefin refers to a resin having structural units derived from olefins.

[0080] The polyolefin may be linear or branched, and may have a cyclic structure, such as polycycloolefin.

[0081] Examples of polyolefins include polyethylene, polypropylene (PP), polymethylpentene (TPX manufactured by Mitsui Chemicals, Inc., etc.), hydrogenated polybutadiene, cycloolefin polymer (COP, Zeonor manufactured by Nippon Zeon Co., Ltd., etc.), and cycloolefin copolymer (COC, Apel manufactured by Mitsui Chemicals, Inc., etc.).

[0082] The polyethylene may be either high density polyethylene (HDPE) or low density polyethylene (LDPE), or may be linear low density polyethylene (LLDPE).

[0083] The polyolefin may be a copolymer of an olefin and a non-olefin monomer such as an acrylate, methacrylate, styrene, and / or vinyl acetate based monomer.

[0084] An example of the polyolefin copolymer is a styrene-ethylene / butylene-styrene copolymer (SEBS). SEBS may be hydrogenated. However, in order to achieve better effects of the present disclosure, it is preferable that the content of structural units derived from monomers other than olefins is low, and it is more preferable that structural units derived from monomers other than olefins are not included. For example, the content of structural units derived from monomers other than olefins is preferably 0% by mass to 40% by mass, more preferably 0% by mass to 5% by mass, relative to the total mass of the polyolefin.

[0085] Furthermore, the polyolefin preferably does not substantially contain a reactive group, as described below, and the content of structural units having a reactive group is preferably 0% by mass to 3% by mass relative to the total mass of the polyolefin.

[0086] Among these, from the viewpoint of low transmission loss, the polyolefin is preferably polyethylene, cycloolefin polymer (COP), or cycloolefin copolymer (COC), more preferably polyethylene, and even more preferably low-density polyethylene (LDPE).

[0087] From the viewpoint of heat resistance and moldability, the content of the polyolefin is preferably 5% by mass to 30% by mass, and more preferably 10% by mass to 20% by mass, based on the total mass of Layer A.

[0088] - Compatible Component - When Layer A contains a polyolefin in addition to the liquid crystal polymer, it preferably further contains a compatible component.

[0089] Examples of compatible components include polymers (non-reactive compatibilizers) having a portion that is highly compatible or has a high affinity with the liquid crystal polymer, and polymers (reactive compatibilizers) having a group reactive to the phenolic hydroxyl group or carboxyl group at the end of the liquid crystal polymer.

[0090] The reactive group of the reactive compatibilizer is preferably an epoxy group or a maleic anhydride group.

[0091] The miscible component is preferably a polymer having a portion with high compatibility or affinity with the polyolefin. When Layer A contains a polyolefin and a miscible component, a reactive compatibilizer is preferred as the miscible component, since it can finely disperse the polyolefin. The miscible component (particularly the reactive compatibilizer) may form a chemical bond with a component such as a liquid crystal polymer in Layer A.

[0092] Examples of reactive compatibilizers include epoxy group-containing polyolefin copolymers, epoxy group-containing vinyl copolymers, maleic anhydride-containing polyolefin copolymers, maleic anhydride-containing vinyl copolymers, oxazoline group-containing polyolefin copolymers, oxazoline group-containing vinyl copolymers, and carboxy group-containing olefin copolymers. Among these, the reactive compatibilizer is preferably an epoxy group-containing polyolefin copolymer or a maleic anhydride-grafted polyolefin copolymer.

[0093] Examples of epoxy group-containing polyolefin copolymers include ethylene / glycidyl methacrylate copolymer, ethylene / glycidyl methacrylate / vinyl acetate copolymer, ethylene / glycidyl methacrylate / methyl acrylate copolymer, polystyrene graft copolymer to ethylene / glycidyl methacrylate copolymer (EGMA-g-PS), polymethyl methacrylate graft copolymer to ethylene / glycidyl methacrylate copolymer (EGMA-g-PMMA), and acrylonitrile / styrene graft copolymer to ethylene / glycidyl methacrylate copolymer (EGMA-g-AS). Commercially available epoxy group-containing polyolefin copolymers include Bondfast 2C and Bondfast E manufactured by Sumitomo Chemical Co., Ltd.; Lotadar manufactured by Arkema; ​​and Modiper A4100 and Modiper A4400 manufactured by NOF Corporation.

[0094] Examples of epoxy group-containing vinyl copolymers include glycidyl methacrylate grafted polystyrene (PS-g-GMA), glycidyl methacrylate grafted polymethyl methacrylate (PMMA-g-GMA), and glycidyl methacrylate grafted polyacrylonitrile (PAN-g-GMA).

[0095] Examples of maleic anhydride-containing polyolefin copolymers include maleic anhydride-grafted polypropylene (PP-g-MAH), maleic anhydride-grafted ethylene / propylene rubber (EPR-g-MAH), and maleic anhydride-grafted ethylene / propylene / diene rubber (EPDM-g-MAH). Commercially available maleic anhydride-containing polyolefin copolymers include the Orevac G series manufactured by Arkema and the FUSABOND E series manufactured by The Dow Chemical Company.

[0096] Examples of maleic anhydride-containing vinyl copolymers include maleic anhydride-grafted polystyrene (PS-g-MAH), maleic anhydride-grafted styrene / butadiene / styrene copolymer (SBS-g-MAH), maleic anhydride-grafted styrene / ethylene / butene / styrene copolymer (SEBS-g-MAH), styrene / maleic anhydride copolymer, and acrylic acid ester / maleic anhydride copolymer. Commercially available maleic anhydride-containing vinyl copolymers include the Tuftec M series (SEBS-g-MAH) manufactured by Asahi Kasei Corporation.

[0097] In addition to the above, examples of the compatible component include oxazoline-based compatibilizers (e.g., bisoxazoline-styrene-maleic anhydride copolymer, bisoxazoline-maleic anhydride modified polyethylene, and bisoxazoline-maleic anhydride modified polypropylene), elastomer-based compatibilizers (e.g., aromatic resins, petroleum resins), ethylene glycidyl methacrylate copolymer, ethylene maleic anhydride ethyl acrylate copolymer, ethylene glycidyl methacrylate-acrylonitrile styrene, acid-modified polyethylene wax, COOH-modified polyethylene graft polymer, COOH-modified polypropylene graft polymer, polyethylene-polyamide graft copolymer, polypropylene-polyamide graft copolymer, methyl methacrylate-butadiene-styrene copolymer, acrylonitrile-butadiene rubber, EVA-PVC graft copolymer, vinyl acetate-ethylene copolymer, ethylene-α-olefin copolymer, propylene-α-olefin copolymer, hydrogenated styrene-isopropylene-block copolymer, and amine-modified styrene-ethylene-butene-styrene copolymer.

[0098] The compatible component may also be an ionomer resin. Examples of such ionomer resins include ethylene-methacrylic acid copolymer ionomers, ethylene-acrylic acid copolymer ionomers, propylene-methacrylic acid copolymer ionomers, propylene-acrylic acid copolymer ionomers, butylene-acrylic acid copolymer ionomers, ethylene-vinylsulfonic acid copolymer ionomers, styrene-methacrylic acid copolymer ionomers, sulfonated polystyrene ionomers, fluorine-based ionomers, telechelic polybutadiene acrylic acid ionomers, and sulfonated ethylene-propylene ionomers. Examples of ionomers include pyrene-diene copolymer ionomers, hydrogenated polypentamer ionomers, polypentamer ionomers, poly(vinylpyridinium salt) ionomers, poly(vinyltrimethylammonium salt) ionomers, poly(vinylbenzylphosphonium salt) ionomers, styrene-butadiene acrylic acid copolymer ionomers, polyurethane ionomers, sulfonated styrene-2-acrylamido-2-methylpropane sulfate ionomers, acid-amine ionomers, aliphatic ionenes, and aromatic ionenes.

[0099] When Layer A contains a compatible component, the content of the compatible component is preferably 0.05% by mass to 30% by mass, more preferably 0.1% by mass to 20% by mass, and even more preferably 0.5% by mass to 10% by mass, relative to the total mass of Layer A.

[0100] -Heat Stabilizer- From the viewpoint of suppressing thermal oxidative deterioration during melt extrusion film formation, Layer A preferably contains at least one heat stabilizer.

[0101] Examples of thermal stabilizers include phenol-based stabilizers and amine-based stabilizers that have a radical scavenging action; phosphite-based stabilizers and sulfur-based stabilizers that have a peroxide decomposition action; and hybrid stabilizers that have both a radical scavenging action and a peroxide decomposition action.

[0102] Examples of phenol-based stabilizers include hindered phenol-based stabilizers, semi-hindered phenol-based stabilizers, and less-hindered phenol-based stabilizers. Commercially available hindered phenol-based stabilizers include Adeka STAB AO-20, AO-50, AO-60, and AO-330 manufactured by ADEKA Corporation, and Irganox 259, 1035, and 1098 manufactured by BASF. Commercially available semi-hindered phenol-based stabilizers include Adeka STAB AO-80 manufactured by ADEKA Corporation, and Irganox 245 manufactured by BASF. Commercially available less-hindered phenol-based stabilizers include Nocrac 300 manufactured by Ouchi Shinko Chemical Industry Co., Ltd., and Adeka STAB AO-30 and AO-40 manufactured by ADEKA Corporation. Commercially available phosphite stabilizers include, for example, Adekastab 2112, PEP-8, PEP-36, and HP-10 manufactured by ADEKA Corp. Commercially available hybrid stabilizers include, for example, Sumilizer GP manufactured by Sumitomo Chemical.

[0103] When Layer A contains a heat stabilizer, the content of the heat stabilizer is preferably 0.0001% by mass to 10% by mass, more preferably 0.001% by mass to 5% by mass, and even more preferably 0.01% by mass to 2% by mass, relative to the total mass of Layer A.

[0104] Other Additives Layer A may contain additives other than the components described above. Known additives can be used as the other additives. Specific examples include curing agents, leveling agents, antifoaming agents, antioxidants, ultraviolet absorbers, flame retardants, and colorants.

[0105] The average thickness of Layer A is preferably greater than the average thickness of Layer B from the viewpoints of the dielectric loss tangent of the film and adhesion to metal. Ａ and the average thickness T of layer B Ｂ T, which is the ratio of Ａ / T ＢFrom the viewpoints of the dielectric loss tangent of the film and adhesion to the metal, the value of is preferably 0.8 to 10, more preferably 1 to 5, even more preferably more than 1 but not more than 3, and particularly preferably more than 1 but not more than 2. There are no particular restrictions on the average thickness of Layer A, but from the viewpoints of the dielectric loss tangent of the film and adhesion to the metal layer, it is preferably 5 μm to 90 μm, more preferably 10 μm to 70 μm, and particularly preferably 15 μm to 60 μm.

[0106] The method for measuring the average thickness of each layer in the film according to the present disclosure is as follows: The film is cut with a microtome, and the cross section is observed under an optical microscope to evaluate the thickness of each layer. Cross-sectional samples are cut out from three or more locations, and the thickness is measured at three or more points on each cross section, and the average value of these measurements is taken as the average thickness.

[0107] <Layer B> In the film according to the present disclosure, Layer B is disposed on at least one surface of Layer A.

[0108] The elastic modulus EB of Layer B at 160°C is preferably 0.1 GPa or less, more preferably 0.01 GPa or less, and even more preferably 0.002 GPa or less. When the elastic modulus EB of Layer B at 160°C is small, Layer B can deform to conform to steps, improving step conformability. The lower limit of the elastic modulus EB is not particularly limited, and is, for example, 0.00001 GPa.

[0109] From the viewpoints of the dielectric loss tangent of the film and the ability to conform to unevenness, the dielectric loss tangent of Layer B is preferably 0.008 or less, more preferably 0.005 or less, even more preferably 0.002 or less, and particularly preferably more than 0 to 0.001.

[0110] The components constituting Layer B are not particularly limited as long as the elastic modulus EA and the elastic modulus EB satisfy the above ratio. Layer B preferably contains at least one polymer because it is easier to satisfy the above ratio.

[0111] The type of polymer is not particularly limited, and known polymers can be used. Examples of the polymer include (meth)acrylic resin, polyvinyl cinnamate, polycarbonate, polyimide, polyamideimide, polyesterimide, polyetherimide, polyetherketone, polyetheretherketone, polyethersulfone, polysulfone, polyparaxylene, polyester, polyvinyl acetal, polyvinyl chloride, polyvinyl acetate, polyamide, polystyrene, polyurethane, polyvinyl alcohol, cellulose acylate, fluorinated resin, liquid crystal polymer, syndiotactic polystyrene, silicone resin, epoxysilicone resin, phenolic resin, alkyd resin, epoxy resin, maleic acid resin, melamine resin, urea resin, aromatic sulfonamide, benzoguanamine resin, silicone elastomer, and polyolefin. Among these, the polymer is preferably polyimide or polyolefin.

[0112] -Cured product of a composition containing a polymer and a compound having a reactive group- Furthermore, from the viewpoints of adhesion to Layer A and adhesion to the metal layer, Layer B preferably contains a cured product of a composition containing a polymer and a compound having a reactive group. Hereinafter, the compound having a reactive group will also be referred to as a "reactive compound."

[0113] The reactive group of the reactive compound is preferably a group capable of reacting with a group (particularly a group having an oxygen atom, such as a carboxy group or a hydroxy group) that may be present on the surface of Layer A. Furthermore, the reactive group of the reactive compound is preferably a group capable of reacting with a metal surface.

[0114] Examples of the reactive group include an epoxy group, an oxetanyl group, an isocyanate group, an acid anhydride group, a carbodiimide group, an N-hydroxyester group, a glyoxal group, an imide ester group, a halogenated alkyl group, and a thiol group. Among these, the reactive group is preferably at least one group selected from the group consisting of an epoxy group, an acid anhydride group, and a carbodiimide group, and more preferably an epoxy group.

[0115] Examples of compounds having an epoxy group include aromatic glycidyl amines (e.g., N,N-diglycidyl-4-glycidyloxyaniline, 4,4'-methylenebis(N,N-diglycidylaniline), N,N-diglycidyl-o-toluidine, and N,N,N',N'-tetraglycidyl-m-xylylenediamine, 4-t-butylphenyl glycidyl ether); aliphatic glycidyl amines (e.g., 1,3-bis(diglycidylaminomethyl)cyclohexane, etc.); and aliphatic glycidyl ethers (e.g., sorbitol polyglycidyl ether). Of these, aromatic glycidyl amine compounds are preferred as compounds having an epoxy group from the viewpoint of improving adhesion to the metal layer.

[0116] Examples of compounds having an acid anhydride group include tetracarboxylic dianhydrides (e.g., 3,3',4,4'-benzophenonetetracarboxylic dianhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride, pyromellitic dianhydride, 2,3,3',4'-biphenyltetracarboxylic dianhydride, oxydiphthalic dianhydride, diphenylsulfone-3,4,3',4'-tetracarboxylic dianhydride, bis(3,4-dicarboxyphenyl)sulfide dianhydride, 2,2-bis(3,4-dicarboxyphenyl)-1,1,1,3,3,3-hexafluoropropane dianhydride, 2,3,3',4'-benzophenonetetracarboxylic dianhydride, bis(3,4-dicarboxyphenyl)methane dianhydride, 2,2-bis(3,4-dicarboxyphenyl)propane dianhydride, p-phenyl Examples of suitable dianhydrides include m-terphenyl-3,4,3',4'-tetracarboxylic dianhydride, p-biphenylene bis(trimellitic acid monoester acid anhydride), m-terphenyl-3,4,3',4'-tetracarboxylic dianhydride, p-terphenyl-3,4,3',4'-tetracarboxylic dianhydride, 1,3-bis(3,4-dicarboxyphenoxy)benzene dianhydride, 1,4-bis(3,4-dicarboxyphenoxy)benzene dianhydride, 1,4-bis(3,4-dicarboxyphenoxy)biphenyl dianhydride, 2,2-bis[(3,4-dicarboxyphenoxy)phenyl]propane dianhydride, 2,3,6,7-naphthalenetetracarboxylic dianhydride, 1,4,5,8-naphthalenetetracarboxylic dianhydride, and 4,4'-(2,2-hexafluoroisopropylidene)diphthalic dianhydride.

[0117] Examples of compounds having a carbodiimide group include monocarbodiimide compounds (e.g., dicyclohexylcarbodiimide, diisopropylcarbodiimide, dimethylcarbodiimide, diisobutylcarbodiimide, dioctylcarbodiimide, t-butylisopropylcarbodiimide, diphenylcarbodiimide, di-t-butylcarbodiimide, di-β-naphthylcarbodiimide, and N,N′-di-2,6-diisopropylphenylcarbodiimide), and polycarbodiimide compounds (e.g., compounds produced by the methods described in U.S. Pat. No. 2,941,956, Japanese Patent Publication No. 47-033279, J. Org. Chem., Vol. 28, pp. 2069-2075 (1963), and Chemical Review 1981, Vol. 81, No. 4, pp. 619-621, etc.). Commercially available reactive compounds having a carbodiimide group include Carbodilite (registered trademark) HMV-8CA, LA-1, and V-03 (all manufactured by Nisshinbo Chemical Inc.), Stabaxol (registered trademark) P, P100, and P400 (all manufactured by Rhein Chemie), and Stabilizer 9000 (trade name, manufactured by Rhein Chemie).

[0118] The number of reactive groups possessed by the reactive compound is 1 or more, but from the viewpoint of superior adhesion to the metal layer, the number is preferably 3 or more. From the viewpoint of adhesion strength and film strength, the number of reactive groups possessed by the reactive compound is preferably 6 or less, more preferably 5 or less, and even more preferably 4 or less.

[0119] The reactive compounds may be used alone or in combination of two or more.

[0120] Among these, the cured product of the composition containing a polymer and a compound having a reactive group is preferably a cured product of a composition containing a polyimide and an epoxy compound, or a cured product of a composition containing a polyolefin and an epoxy compound.

[0121] The polyimide is not particularly limited as long as it is a polymer containing an imide bond. The polyolefin may be the same as the polyolefin that can be contained in Layer A.

[0122] As the polyolefin, from the viewpoint of low transmission loss, polyethylene, cycloolefin polymer (COP), cycloolefin copolymer (COC), or styrene-ethylene / butylene-styrene copolymer (SEBS) is preferred, and polyethylene or SEBS is more preferred.

[0123] Filler: Layer B may contain at least one filler from the viewpoints of the thermal expansion coefficient and adhesion to the metal layer.

[0124] The filler may be particulate or fibrous. The filler may be inorganic or organic. From the viewpoint of the dielectric loss tangent and step conformability of the film, the filler is preferably an organic filler.

[0125] Known organic fillers can be used as the organic filler, and examples of the organic filler material include polyethylene, polystyrene, urea-formalin filler, polyester, cellulose, acrylic resin, fluororesin, hardened epoxy resin, crosslinked benzoguanamine resin, crosslinked acrylic resin, liquid crystal polymer, and materials containing two or more of these.

[0126] The organic filler may be fibrous, such as nanofibers, or hollow resin particles. Among these, from the viewpoint of the dielectric loss tangent and step conformability of the film, the organic filler is preferably fluororesin particles, polyester-based resin particles, polyethylene particles, liquid crystal polymer particles, or nanofibers of cellulose-based resins, more preferably polytetrafluoroethylene particles, polyethylene particles, or liquid crystal polymer particles, and particularly preferably liquid crystal polymer particles. Here, the liquid crystal polymer particles refer to, but are not limited to, powdered liquid crystals obtained by polymerizing a liquid crystal polymer and pulverizing it with a pulverizer or the like. The liquid crystal polymer particles are preferably smaller than the thickness of each layer.

[0127] The average particle size of the organic filler is preferably 5 nm to 20 μm, more preferably 100 nm to 10 μm, from the viewpoints of the dielectric loss tangent of the film, suitability for laser processing, and ability to conform to unevenness.

[0128] As the inorganic filler, known inorganic fillers can be used. Examples of the material of the inorganic filler include BN and Al. ２ O ３ , AlN, TiO ２ , SiO ２ , barium titanate, strontium titanate, aluminum hydroxide, calcium carbonate, and materials containing two or more of these.

[0129] Among these, from the viewpoints of the thermal expansion coefficient and adhesion to the metal layer, the inorganic filler is preferably metal oxide particles or fibers, more preferably silica particles, titania particles, or glass fibers, and particularly preferably silica particles or glass fibers.

[0130] The average particle size of the inorganic filler is preferably about 20% to about 40% of the thickness of Layer A, and may be selected to be, for example, 25%, 30%, or 35% of the thickness of Layer A. When the particles or fibers are flat, the average particle size indicates the length in the direction of the short side.

[0131] Furthermore, from the viewpoints of the thermal expansion coefficient and adhesion to the metal layer, the average particle size of the inorganic filler is preferably 5 nm to 20 μm, more preferably 10 nm to 10 μm, even more preferably 20 nm to 1 μm, and particularly preferably 25 nm to 500 nm.

[0132] Other Additives Layer B may contain additives other than the components described above. Known additives can be used as the other additives. Specific examples include curing agents, leveling agents, antifoaming agents, antioxidants, ultraviolet absorbers, flame retardants, and colorants.

[0133] The average thickness of Layer B is not particularly limited, but from the viewpoint of conformability to unevenness, it is preferably 15 μm or less, more preferably 10 μm or less, and particularly preferably 5 μm or less. The lower limit of the average thickness of Layer B is not particularly limited, and is, for example, 1 μm.

[0134] Layer B is preferably the surface layer (outermost layer) of the film. The layer structure of the film is preferably Layer A / Layer B or Layer B / Layer A / Layer B.

[0135] <Layer C> The film according to the present disclosure preferably further includes Layer C, with Layer C, Layer A, and Layer B being arranged in this order.

[0136] Layer C is a layer different from Layer A in terms of composition and physical properties. Layer C may be the same as or different from Layer B in terms of composition and physical properties. Layer C having the same composition as Layer A or Layer B means that the types and contents of components contained in the layers are the same.

[0137] Layer C preferably comprises at least one polymer.

[0138] The type of polymer is not particularly limited, and known polymers can be used.

[0139] From the viewpoint of adhesion to Layer A and adhesion to the metal layer, Layer C preferably contains a cured product of a composition containing a polymer and a reactive compound. Preferred embodiments of the cured product of the composition containing a polymer and a reactive compound are the same as the preferred embodiments of the cured product of the composition containing a polymer and a reactive compound in Layer B.

[0140] Layer C may contain at least one filler from the viewpoints of the thermal expansion coefficient and adhesion to the metal layer.

[0141] Examples of fillers that may be contained in Layer C include the same fillers that may be contained in Layer B.

[0142] Layer C may contain additives other than the above-mentioned components. Examples of the additives include known additives. Specific examples include curing agents, leveling agents, antifoaming agents, antioxidants, ultraviolet absorbers, flame retardants, and colorants.

[0143] The average thickness of Layer C is preferably smaller than the average thickness of Layer A from the viewpoints of the dielectric loss tangent of the film and adhesion to metals.

[0144] Average thickness T of layer AＡ and the average thickness T of layer C Ｃ T, which is the ratio of Ａ / T Ｃ From the viewpoint of the dielectric loss tangent of the film and the adhesion to the metal layer, the value of is preferably greater than 1, more preferably from 2 to 100, even more preferably from 2.5 to 20, and particularly preferably from 3 to 10.

[0145] The average thickness of Layer C is not particularly limited, but from the viewpoint of low transmission loss, it is preferably 15 μm or less, more preferably 10 μm or less, and particularly preferably 5 μm or less. The lower limit of the average thickness of Layer C is not particularly limited, and is, for example, 1 μm.

[0146] The average thickness of the film according to the present disclosure is preferably 6 μm to 200 μm, more preferably 12 μm to 100 μm, and particularly preferably 20 μm to 80 μm, from the viewpoints of strength and electrical properties (characteristic impedance) when laminated with a metal layer.

[0147] The average thickness of the film is determined by measuring any five points using an adhesive film thickness meter, for example, an electronic micrometer (product name "KG3001A" manufactured by Anritsu Corporation), and averaging these values.

[0148] [Film Manufacturing Method] The film manufacturing method according to the present disclosure is not particularly limited and may include, for example, a step of forming layer A using a composition for forming layer A (layer A-forming composition) (hereinafter also referred to as "step A"), and a step of forming layer B using a composition for forming layer B (layer B-forming composition) (hereinafter also referred to as "step B") on at least one surface of layer A formed in step A. Steps A and B will be described below.

[0149] <Step A> Step A includes, for example, a pelletizing step of kneading the raw materials for forming the above-described layer A (raw materials for forming layer A) to obtain pellets, and a film-forming step of producing a molded body using the pellets. The produced molded body becomes layer A in the film. Step A will be described in detail below.

[0150] (Pelletization step) (1) Form of raw material As the polymer to be used for film formation, a polymer in the form of pellets, flakes, or powder may be used as it is. For the purpose of stabilizing the film formation or uniformly dispersing components other than the polymer, it is preferable to use pellets obtained by kneading one or more raw materials using an extruder and pelletizing them.

[0151] (2) Alternative to drying by drying or venting When pelletizing, it is preferable to dry the raw material beforehand. Drying methods include circulating heated air with a low dew point and dehumidifying by vacuum drying. In particular, when using a polymer that is easily oxidized, vacuum drying or drying using an inert gas is preferable.

[0152] (3) Raw Material Supply Method The raw material supply method may be a method in which the raw materials are mixed and supplied in advance before being kneaded and pelletized, a method in which the raw materials are supplied separately to the extruder so as to be in a constant ratio, or a combination of both methods.

[0153] (4) Extrusion Process Atmosphere When melt-extrusion is performed, it is preferable to prevent heat and oxidative degradation as much as possible within the range that does not hinder uniform dispersion, and it is also effective to reduce the oxygen concentration by reducing the pressure using a vacuum pump or by introducing an inert gas. These methods may be performed alone or in combination.

[0154] (5) Temperature The kneading temperature is preferably set to a temperature equal to or lower than the thermal decomposition temperature of the raw materials, and is preferably set as low as possible within a range in which the load on the extruder and the deterioration of uniform kneading do not become a problem.

[0155] (6) Pressure Pelletization is preferably carried out at a pressure of 0.05 MPa to 30 MPa. In the case of raw materials that are prone to discoloration or gelation due to shear, it is preferable to apply an internal pressure of about 1 MPa to 10 MPa to the extruder to fill the extruder with the raw materials.

[0156] (7) Pelletization Method A common pelletization method is to extrude a noodle-shaped material, solidify it in water, and then cut it. Pelletization may be performed by an underwater cutting method in which the material is melted in an extruder and then extruded directly into water through a nozzle while being cut, or by a hot cutting method in which the material is cut while still hot.

[0157] (8) Pellet size The pellet size is 1 mm in cross section. ２ ~300mm ２ and the length is preferably 1 mm to 30 mm, and the cross-sectional area is preferably 2 mm ２ ~100mm ２ and more preferably, the length is 1.5 mm to 10 mm.

[0158] (Drying) (1) Purpose of Drying It is preferable to reduce the moisture and volatile components in the pellets before melt film formation, and drying the pellets is effective. By reducing the moisture or volatile components in the pellets, it is possible to suppress deterioration of appearance due to the inclusion of bubbles or a decrease in haze, and to suppress deterioration of physical properties due to scission of polymer molecular chains, or the occurrence of roll contamination due to the generation of monomers or oligomers. Furthermore, depending on the type of polymer used, removal of dissolved oxygen by drying may also be able to suppress the generation of oxidized crosslinked products during melt film formation.

[0159] (2) Drying Method / Heating Method As for the drying method, a dehumidifying hot air dryer is generally used from the viewpoint of drying efficiency and economy, but there are no particular limitations as long as the target moisture content can be obtained. Furthermore, the drying method can be appropriately selected according to the physical properties of the polymer. Examples of heating methods include pressurized steam, heater heating, far-infrared radiation, microwave heating, and heat medium circulation heating.

[0160] (Film Forming Process) The film forming process will be described below.

[0161] (1) Extrusion Conditions Drying of Raw Materials In the melt-plasticizing process of pellets using an extruder, it is preferable to reduce the moisture and volatile components, as in the pelletizing process, and drying the pellets is effective.

[0162] Raw Material Supply Method When multiple types of raw materials (pellets) are fed through the feed port of the extruder, they may be mixed in advance (premix method), or they may be fed separately into the extruder at a constant ratio, or a combination of both methods may be used. Furthermore, to stabilize extrusion, it is common practice to minimize fluctuations in the temperature and bulk density of the raw materials fed through the feed port. From the standpoint of plasticization efficiency, the raw material temperature may be within a range that does not cause adhesion and blocking at the feed port, and a high temperature is preferred. In the case of an amorphous state, it is preferable to adjust the raw material temperature to a temperature 150°C lower than the glass transition temperature or higher and 1°C lower than the glass transition temperature or lower. In the case of a crystalline resin, it is preferable to adjust the raw material temperature to a temperature 150°C lower than the melting point or higher and 1°C lower than the melting point or lower. From the standpoint of plasticization efficiency, the bulk density of the raw material is preferably 0.3 times or higher, more preferably 0.4 times or higher, than that in the molten state. When the bulk specific gravity of the raw material is less than 0.3 times the specific gravity in the molten state, it is also preferable to subject the raw material to processing such as compressing it into pseudo-pellets.

[0163] As in the pelletizing process, the atmosphere during melt extrusion must be such that heat and oxidative degradation are prevented as much as possible without interfering with uniform dispersion, and it is effective to inject an inert gas (such as nitrogen), reduce the oxygen concentration in the extruder using a vacuum hopper, or provide a vent port in the extruder and reduce the pressure using a vacuum pump. These methods of reducing pressure and injecting an inert gas may be carried out independently or in combination.

[0164] Rotational Speed ​​The rotational speed of the extruder is preferably 5 rpm (revolutions per minute) to 300 rpm, more preferably 10 rpm to 200 rpm, and even more preferably 15 rpm to 100 rpm. If the rotational speed is equal to or higher than the lower limit, the residence time is shortened, and it is possible to suppress a decrease in molecular weight due to thermal degradation and to suppress discoloration. If the rotational speed is equal to or lower than the upper limit, it is possible to suppress scission of molecular chains due to shear, and it is possible to suppress a decrease in molecular weight and an increase in crosslinked gel. It is preferable to select an appropriate condition for the rotational speed from the viewpoints of both uniform dispersion and thermal degradation due to an extended residence time.

[0165] Temperature: The barrel temperatures (feed zone temperature T1°C, compression zone temperature T2°C, metering zone temperature T3°C) are generally determined by the following method. When pellets are melted and plasticized in an extruder at a target temperature T°C, the metering zone temperature T3 is set to T±20°C, taking into account the amount of shear heat generated. T2 is set within the range of T3±20°C, taking into account extrusion stability and the thermal decomposition of the raw materials. T1 is generally set at a temperature at least 150°C lower than T2 and not more than 5°C lower than T2, with the optimal value being selected from the viewpoints of both ensuring friction between the raw materials and the barrel, which acts as the driving force (feed force) for feeding the raw materials, and preheating in the feed zone. In a typical extruder, it is possible to set the temperatures by dividing the zones T1 to T3 into smaller zones. Setting the temperature so that the temperature change between each zone is gradual allows for greater stability. In this case, T is preferably set below the thermal degradation temperature of the raw materials. If the shear heat generated by the extruder exceeds the thermal degradation temperature, it is common to actively cool and remove the shear heat. In order to achieve both improved dispersibility and thermal degradation, it is also effective to melt and mix the raw materials at a relatively high temperature in the first half of the extruder and then lower the temperature of the raw materials in the second half.

[0166] Pressure: The pressure inside the extruder is generally 1 MPa to 50 MPa, preferably 2 MPa to 30 MPa, and more preferably 3 MPa to 20 MPa, in terms of extrusion stability and melt uniformity. If the pressure inside the extruder is 1 MPa or higher, the melt filling rate inside the extruder is sufficient, which can prevent the destabilization of the extrusion pressure and the generation of foreign matter due to the generation of stagnation areas. Furthermore, if the pressure inside the extruder is 50 MPa or lower, it can prevent excessive shear stress inside the extruder, which can prevent thermal decomposition due to an increase in the temperature of the raw materials.

[0167] Residence time The residence time in the extruder (residence time during film formation) can be calculated from the volume of the extruder and the discharge volume of the polymer, as in the pelletization process. The residence time is preferably 10 seconds to 60 minutes, more preferably 15 seconds to 45 minutes, and even more preferably 30 seconds to 30 minutes. A residence time of 10 seconds or more ensures sufficient melt plasticization and dispersion of other components. A residence time of 30 minutes or less is preferred in that it can suppress polymer degradation and discoloration.

[0168] (Filtration) Types, purpose of installation, and structure: To prevent damage to the gear pump due to foreign matter contained in the raw material and to extend the life of the fine-pore filter installed downstream of the extruder, a filtration facility is generally installed at the extruder outlet. It is preferable to use a so-called breaker plate type filtration, in which a mesh filter material is combined with a strong reinforcing plate with a high opening ratio.

[0169] Mesh Size and Filtration Area: The mesh size is preferably 40 to 800 mesh, more preferably 60 to 700 mesh, and even more preferably 100 to 600 mesh. A mesh size of 40 mesh or greater can adequately prevent foreign matter from passing through the mesh. Furthermore, a mesh size of 800 mesh or less can suppress the increase in filtration pressure speed, reducing the frequency of mesh replacement. In addition, filter meshes of different mesh sizes are often stacked together to maintain filtration accuracy and strength. Furthermore, since a large filtration opening area can be achieved and mesh strength can be maintained, the filter mesh is sometimes reinforced using a breaker plate. The opening ratio of the breaker plate used is often 30% to 80% in terms of filtration efficiency and strength. Furthermore, a screen changer with the same diameter as the barrel diameter of the extruder is often used. However, to increase the filtration area, tapered piping can be used to allow for a larger diameter filter mesh, or multiple breaker plates can be used by branching the flow path. The filtration area is determined based on a flow rate of 0.05 g / cm per second. ２ ~5g / cm ２ It is preferable to select it based on 0.1 g / cm ２ ~3g / cm ２ More preferably, 0.2 g / cm ２ ~2 g / cm ２is more preferable. The capture of foreign matter causes the filter to become clogged, increasing the filtration pressure. In this case, the extruder must be stopped and the filter replaced, but a type of filter that allows the filter to be replaced while extrusion is continuing can also be used. Furthermore, as a countermeasure against the increase in filtration pressure due to the capture of foreign matter, a filter that has the function of reducing the filtration pressure by reversing the polymer flow path and washing away the foreign matter captured in the filter can also be used.

[0170] (Die) Type, structure, and material After foreign matter has been removed by filtration and the temperature has been made uniform by a mixer, the raw material is continuously sent to the die. There are no particular restrictions on the die as long as it is designed to minimize retention of the raw material, and any of the commonly used types of T-die, fishtail die, and hanger coat die can be used. Among these, the hanger coat die is preferred in terms of thickness uniformity and minimal retention.

[0171] Multilayer Film Formation For film formation, for example, a single-layer film forming apparatus with low equipment costs is used. Alternatively, a multilayer film forming apparatus may be used to produce a film having functional layers such as Layer B, a surface protective layer, an adhesive layer, an easy-adhesion layer, and / or an antistatic layer. Specific examples include a method of multi-layering using a multilayer feed block and a method using a multi-manifold die. It is preferable to thinly laminate the functional layer on the surface layer, but the layer ratio is not particularly limited.

[0172] The casting film-forming process preferably includes a step of supplying molten raw material from a supply means and a step of landing the molten raw material on a casting roll to form a film. The molded body may be cooled and solidified and wound up as is, or it may be passed between a pair of clamping surfaces and continuously clamped to form a film. There are no particular limitations on the means for supplying the molten raw material (melt). For example, a specific melt supply means may be an extruder that melts the raw material and extrudes it into a film, or an extruder and die. Alternatively, the raw material may be solidified into a film, and then melted by a heating means to form a melt, which is then supplied to the film-forming process. When the molten resin extruded into a sheet form from the die is clamped by a device having a pair of clamping surfaces, the surface morphology of the clamping surfaces can be transferred to the surface of the molded body. Furthermore, when the raw material contains a liquid crystal polymer, the orientation can be controlled by applying elongation deformation.

[0173] Film-forming methods and types: Among methods for forming molten raw materials into a film, passing the material between two rolls (e.g., a touch roll and a chill roll) is preferred because it allows for the application of high clamping pressure and results in an excellent surface shape of the molded product. In this specification, when multiple casting rolls are used to transport the molten material, the casting roll closest to the most upstream supply means (e.g., a die) is referred to as the chill roll. Other methods include clamping between metal belts or combining a roll with a metal belt. In some cases, to improve adhesion with the roll or metal belt, a combination of film-forming methods such as electrostatic application, air knife, air chamber, and vacuum nozzle methods can be used on a casting drum. Furthermore, when obtaining a multilayered molded product, it is preferable to obtain it by clamping raw materials extruded in multiple layers from a die. However, a single-layered molded product can also be introduced into the clamping section in a melt lamination manner to obtain a multilayered molded product. Furthermore, by changing the difference in peripheral speed of the pressing section or the direction of the orientation axis, a molded product having a different gradient structure in the thickness direction can be obtained, and by performing this process several times, a molded product having three or more layers can be obtained. Furthermore, deformation can be imparted by periodically vibrating the touch roll in the TD direction during pressing.

[0174] Temperature of molten raw material From the viewpoint of improving formability and suppressing deterioration, the discharge temperature (temperature of the raw material at the outlet of the supply means) is preferably in the range of at least 10°C lower than the melting point of the raw material and not more than 40°C higher than the melting point of the raw material. The melt viscosity is preferably 50 Pa·s to 3500 Pa·s. It is preferable that the temperature change due to cooling of the molten raw material across the air gap is as small as possible. It is preferable to minimize the temperature drop due to cooling by devising measures such as increasing the film formation speed and shortening the air gap.

[0175] Touch Roll Temperature The temperature of the touch roll is preferably set to the glass transition temperature (Tg) of the raw material or lower. If the temperature of the touch roll is equal to or lower than the Tg of the polymer, adhesion of the raw material to the roll can be suppressed, resulting in a good appearance of the molded product. For the same reason, the chill roll temperature is also preferably set to the Tg of the raw material or lower.

[0176] - Film-forming procedure In the film-forming process, from the viewpoint of the film-forming process and stabilization of quality, it is preferable to form the film by letting the molten raw material discharged from the die land on a cast roll and form it into a film, which is then cooled and solidified, and wound up. When the molten raw material is pressed, the molten raw material is passed between a first pressing surface and a second pressing surface set at a predetermined temperature, cooled and solidified, and then wound up.

[0177] (Stretching step, heat-relaxing treatment, heat-setting treatment) Furthermore, after obtaining an unstretched molded body by the above method, it may be stretched continuously or discontinuously and / or heat-relaxed or heat-set. For example, each step may be performed in the following combinations of (a) to (g). Furthermore, the order of longitudinal stretching and transverse stretching may be reversed, the longitudinal stretching and transverse stretching steps may be performed in multiple stages, or the longitudinal stretching and transverse stretching steps may be combined with oblique stretching or simultaneous biaxial stretching. (a) Transverse stretching (b) Transverse stretching → heat-relaxing treatment (c) Longitudinal stretching (d) Longitudinal stretching → heat-relaxing treatment (e) Longitudinal (transverse) stretching → transverse (longitudinal) stretching (f) Longitudinal (transverse) stretching → transverse (longitudinal) stretching → heat-relaxing treatment (g) Transverse stretching → heat-relaxing treatment → longitudinal stretching → heat-relaxing treatment

[0178] Longitudinal stretching Longitudinal stretching can be achieved by increasing the peripheral speed at the outlet side compared to the peripheral speed at the inlet side while heating the space between two pairs of rolls. To prevent curling, it is preferable that the front and back surfaces of the molded article to be stretched be at the same temperature. However, when controlling the optical properties in the thickness direction, stretching can be performed at different temperatures on the front and back surfaces. The stretching temperature here is defined as the temperature on the lower surface side of the molded article. The longitudinal stretching process can be performed in one stage or multiple stages. Preheating of the unstretched molded article is often performed by passing it through temperature-controlled heating rolls, but in some cases, heating can also be performed using a heater. Furthermore, to prevent the molded article to be stretched from sticking to the rolls, ceramic rolls with improved adhesiveness can also be used.

[0179] Transverse Stretching Conventional transverse stretching can be used in the transverse stretching step. That is, conventional transverse stretching includes a stretching method in which both ends of the molded body to be stretched in the width direction are held with clips and the clips are widened using a tenter while heating in an oven. For the transverse stretching step, for example, the methods described in Japanese Utility Model Laid-Open Publication Nos. 62-035817, 2001-138394, 10-249934, 6-270246, 4-030922, and 62-152721 can be used, and these methods are incorporated herein by reference.

[0180] The stretching ratio in the width direction of the molded body in the transverse stretching step (transverse stretching ratio) is preferably 1.2 to 6 times, more preferably 1.5 to 5 times, and even more preferably 2 to 4 times. Furthermore, when longitudinal stretching is performed, the transverse stretching ratio is preferably greater than the stretching ratio in the longitudinal stretching. The stretching temperature in the transverse stretching step can be controlled by blowing air of a desired temperature into the tenter. For the same reasons as in longitudinal stretching, the film temperature may be the same or different on the front and back sides. The stretching temperature used here is defined as the temperature on the lower side of the surface of the molded body. The transverse stretching step may be performed in one stage or multiple stages. Furthermore, when transverse stretching is performed in multiple stages, it may be performed continuously or intermittently with a zone in between where no width expansion occurs. In addition to the usual transverse stretching in which clips are used to expand the width in the tenter, the following stretching method, in which the film is gripped with clips in a similar manner, can also be applied to such transverse stretching.

[0181] Oblique Stretching In the oblique stretching step, the clips are expanded in the lateral direction as in normal lateral stretching, but stretching can be performed in the oblique direction by changing the conveying speed of the left and right clips. As the oblique stretching step, for example, the methods described in JP-A-2002-022944, JP-A-2002-086554, JP-A-2004-325561, JP-A-2008-023775, and JP-A-2008-110573 can be used.

[0182] Simultaneous Biaxial Stretching Simultaneous biaxial stretching is a process in which the clip is expanded in the transverse direction, and simultaneously stretched or contracted in the longitudinal direction, similar to normal transverse stretching. As the simultaneous biaxial stretching, for example, the methods described in Japanese Utility Model Laid-Open Publication No. 55-093520, Japanese Patent Laid-Open Publication No. 63-247021, Japanese Patent Laid-Open Publication No. 6-210726, Japanese Patent Laid-Open Publication No. 6-278204, Japanese Patent Laid-Open Publication No. 2000-334832, Japanese Patent Laid-Open Publication No. 2004-106434, Japanese Patent Laid-Open Publication No. 2004-195712, Japanese Patent Laid-Open Publication No. 2006-142595, Japanese Patent Laid-Open Publication No. 2007-210306, Japanese Patent Laid-Open Publication No. 2005-022087, Japanese Patent Laid-Open Publication No. 2006-517608, and Japanese Patent Laid-Open Publication No. 2007-210306 can be used.

[0183] Heat Treatment to Improve Bowing (Axis Misalignment) During the transverse stretching process, the edges of the molded body are held by clips. Therefore, deformation of the molded body due to thermal shrinkage stress during heat treatment is greater in the center of the molded body and smaller at the edges, resulting in a distribution of properties in the width direction. If a straight line is drawn along the width direction on the surface of the molded body before the heat treatment process, the straight line on the surface of the molded body after the heat treatment process will be arch-shaped, with the center concave toward the downstream. This phenomenon, known as bowing, disrupts the isotropy and width direction uniformity of the molded body. To improve this, preheating before transverse stretching or heat setting after stretching can reduce the variation in orientation angle associated with bowing. While either preheating or heat setting may be performed, both are more preferable. Preheating and heat setting are preferably performed while the molded body is held by clips, i.e., consecutively with stretching.

[0184] The preheating temperature is preferably about 1°C to 50°C higher than the stretching temperature, more preferably 2°C to 40°C higher, and even more preferably 3°C to 30°C higher. The preheating time is preferably 1 second to 10 minutes, more preferably 5 seconds to 4 minutes, and even more preferably 10 seconds to 2 minutes. During preheating, it is preferable to keep the width of the tenter almost constant. Here, "almost" refers to ±10% of the width of the unstretched film.

[0185] The heat setting temperature is preferably 1°C to 50°C lower than the stretching temperature, more preferably 2°C to 40°C lower, and even more preferably 3°C to 30°C lower. A temperature lower than the stretching temperature and lower than the Tg of the liquid crystal polymer is particularly preferred. The heat setting time is preferably 1 second to 10 minutes, more preferably 5 seconds to 4 minutes, and even more preferably 10 seconds to 2 minutes. During heat setting, it is preferable to keep the tenter width approximately constant. Here, "approximately" refers to 0% (the same width as the tenter width after stretching) to -30% (reduced width by 30% from the tenter width after stretching). Other known methods include those described in JP-A-1-165423, JP-A-3-216326, JP-A-2002-018948, and JP-A-2002-137286.

[0186] - Heat Relaxation Treatment After the stretching step, the molded body may be heated to undergo a heat relaxation treatment in which the molded body is shrunk. By performing the heat relaxation treatment, the thermal shrinkage rate of the film can be reduced. The heat relaxation treatment is preferably performed at least once after film formation, after longitudinal stretching, and after transverse stretching. The heat relaxation treatment may be performed online continuously after stretching, or may be performed offline after winding up after stretching. The temperature for the heat relaxation treatment may be, for example, from the glass transition temperature Tg to the melting point Tm of the raw material. When oxidative degradation of the polymer is a concern, the heat relaxation treatment may be performed in an inert gas such as nitrogen gas, argon gas, or helium gas.

[0187] (Annealing Treatment) In step A, it is preferable to perform an annealing treatment in which the molded body is heated after stretching it, since this results in better electrical properties. The heating temperature in the annealing treatment is preferably a temperature 200°C lower than the melting point, more preferably a temperature 100°C lower than the melting point, and even more preferably a temperature 50°C lower than the melting point, where Tm (°C) is the melting point of the raw material. The upper limit of the heating temperature in the annealing treatment is preferably a temperature 50°C higher than the melting point, more preferably a temperature 30°C higher than the melting point. The heating temperature in the annealing treatment is preferably 240°C or higher, more preferably 255°C or higher, and even more preferably 270°C or higher. The heating temperature in the annealing treatment is preferably 370°C or lower, more preferably 350°C or lower.

[0188] Examples of heating means used in the annealing treatment include a hot air drying oven and an infrared heater, with an infrared heater being preferred because it allows for the production of a film with the desired melting peak area in a short time. Alternatively, pressurized steam, microwave heating, and a heat medium circulation heating method may also be used as the heating means. The treatment time for the annealing treatment can be adjusted appropriately depending on the type of raw material, the heating means, and the heating temperature. When an infrared heater is used, the treatment time is preferably 1 to 120 seconds, more preferably 3 to 90 seconds. When a hot air drying oven is used, the treatment time is preferably 1 to 14 hours, more preferably 2 to 10 hours.

[0189] (Surface Treatment) It is preferable to perform a surface treatment on the molded body, since this can further improve the adhesion between the molded body and the metal layer or other layer. Examples of the surface treatment include glow discharge treatment, ultraviolet irradiation treatment, corona treatment, flame treatment, and acid or alkali treatment. The glow discharge treatment here refers to 10 －３ The glow discharge treatment may be performed using a low-temperature plasma generated under a low-pressure gas of 10 Torr to 20 Torr, or preferably under atmospheric pressure. The glow discharge treatment is performed using a plasma-excitable gas. The plasma-excitable gas is a gas that is excited into plasma under the above conditions, and examples of such gases include argon, helium, neon, krypton, xenon, nitrogen, carbon dioxide, fluorocarbons such as tetrafluoromethane, and mixtures thereof.

[0190] In order to improve the mechanical properties, thermal dimensional stability, or winding shape of the wound molded article, it is also effective to subject the molded article to an aging treatment at a temperature equal to or lower than the glass transition temperature of the raw material. After the film-forming step, the molded article may be subjected to a step of squeezing the molded article with heated rolls and / or a step of stretching the molded article to further improve the smoothness of the molded article.

[0191] In the above manufacturing method, the molded article is a single layer, but the molded article may have a laminated structure in which multiple layers are laminated.

[0192] <Step B> Step B is a step of forming a layer B on the molded body (layer A) produced in step A using a composition for forming layer B, thereby producing a film having layer A and layer B.

[0193] Step B includes, for example, applying a composition for forming layer B to at least one surface of the molded body produced in step A, and drying and / or curing the applied film as necessary to form layer B on the molded body.

[0194] Examples of the composition for forming layer B include a composition containing the above-mentioned polymer and a reactive compound.

[0195] The solvent may be used alone or in combination of two or more. The content of the solvent contained in the layer B-forming composition is preferably 0.02 mass% or less, more preferably 0.01 mass% or less, relative to the total mass of the layer B-forming composition. The lower limit is not particularly limited and may be 0 mass%. The content of the solids content of the layer B-forming composition is preferably 99.98 mass% or more, more preferably 99.99 mass%, relative to the total mass of the layer B-forming composition. The upper limit is not particularly limited and may be 100 mass%. In the present disclosure, the "solids content" of the composition means components excluding solvent and water.

[0196] The method for applying the layer B-forming composition onto the molded body (layer A) is not particularly limited, and examples thereof include bar coating, spray coating, squeegee coating, flow coating, spin coating, dip coating, die coating, inkjet coating, and curtain coating. When drying the layer B-forming composition applied onto the molded body (layer A), the drying conditions are not particularly limited, but the drying temperature is preferably 25°C to 200°C, and the drying time is preferably 1 second to 120 minutes.

[0197] Furthermore, when producing a film having Layer C, Layer A, and Layer B in this order, Layer B can be formed on the molded body (Layer A), and then Layer C can be formed using a composition for forming Layer C in a manner similar to the method for forming Layer B.

[0198] [Laminate] The laminate according to the present disclosure may be any laminate having a film according to the present disclosure laminated thereon, but is preferably a laminate having a film according to the present disclosure and a metal layer disposed on at least one surface of the film.

[0199] Examples of the layer configuration of the laminate according to the present disclosure include the following: Layer A / Layer B / Metal layer Layer B / Layer A / Metal layer Layer C / Layer A / Layer B / Metal layer Layer B / Layer A / Layer C / Metal layer Metal layer / Layer A / Layer B / Metal layer Metal layer / Layer C / Layer A / Layer B / Metal layer Metal layer / Layer C / Layer A / Layer B / Metal layer

[0200] The metal layer may be disposed on only one surface of the film, or on both surfaces of the film, and may be disposed directly on a surface of the film or may be disposed via another layer.

[0201] In particular, when the metal layer is disposed on only one surface of the film, the layer structure of the laminate according to the present disclosure is preferably a layer structure in which Layer B is the outermost layer.

[0202] When the laminate according to the present disclosure includes two metal layers, the two metal layers may be metal layers of the same material, thickness, and shape, or may be metal layers of different materials, thicknesses, and shapes.

[0203] The laminate according to the present disclosure can be produced, for example, by attaching a metal substrate to at least one surface of the film according to the present disclosure. The method for attaching the film according to the present disclosure to the metal substrate is not particularly limited, and a known lamination method can be used.

[0204] The metal layer is preferably a copper layer. The copper base material used to form the copper layer is preferably a rolled copper foil formed by a rolling method or an electrolytic copper foil formed by an electrolytic method.

[0205] The average thickness of the metal layer, preferably the copper layer, is not particularly limited, but is preferably 2 μm to 30 μm, more preferably 3 μm to 20 μm, and even more preferably 5 μm to 18 μm. The copper foil may be a carrier-attached copper foil formed releasably on a support (carrier). Any known carrier can be used. The average thickness of the carrier is not particularly limited, but is preferably 10 μm to 100 μm, and more preferably 18 μm to 50 μm.

[0206] The surface roughness Ra of the metal layer is preferably 1.0 μm or less, more preferably 0.5 μm or less. If the surface roughness Ra is 1.0 μm or less, the surface resistance at the interface between the film and the metal layer decreases.

[0207] The surface roughness Ra in the present disclosure is calculated using a surface roughness meter, for example, a stylus-type surface roughness meter "Surfcorder SE3500" manufactured by Kosaka Laboratory Ltd., based on the calculation method for arithmetic mean surface roughness Ra of JIS B0601:2013.

[0208] In measuring the surface roughness Ra, the metal layer in the laminate is removed by etching using an iron chloride solution, and then the surface roughness Ra of the film surface that was in contact with the metal layer to which the surface roughness of the metal layer has been transferred is measured, and this is taken as the surface roughness Ra of the metal layer.

[0209] [Wiring Board] The wiring board according to the present disclosure is preferably a wiring board having a film according to the present disclosure, metal wiring arranged on one surface of the film, and a metal layer arranged on the other surface of the film.

[0210] Examples of layer configurations of the wiring board according to the present disclosure include the following: Metal layer / Layer A / Layer B / Metal wiring Metal layer / Layer B / Layer A / Metal wiring Metal layer / Layer C / Layer A / Layer B / Metal wiring Metal layer / Layer B / Layer A / Layer C / Metal wiring

[0211] The metal layer and the metal wiring may be disposed directly on the surface of the film, or may be disposed via another layer.

[0212] In particular, it is preferable that the metal wiring is disposed on Layer B in a film in which Layer B is the outermost layer.

[0213] The metal wiring according to the present disclosure can be formed, for example, by attaching a metal substrate to both sides of the film according to the present disclosure and then etching one of the metal layers using a known method.

[0214] The metal layer is preferably a copper layer. The metal wiring is preferably a copper wiring. The copper base material used to form the copper layer and the copper wiring is preferably a rolled copper foil formed by a rolling method or an electrolytic copper foil formed by an electrolytic method.

[0215] The average thickness of the metal layer, preferably the copper layer, is not particularly limited, but is preferably 2 μm to 30 μm, more preferably 3 μm to 20 μm, and even more preferably 5 μm to 18 μm. The copper foil may be a carrier-attached copper foil formed releasably on a support (carrier). Any known carrier can be used. The average thickness of the carrier is not particularly limited, but is preferably 10 μm to 100 μm, and more preferably 18 μm to 50 μm.

[0216] The average thickness of the metal wiring, preferably the copper wiring, is not particularly limited, but is preferably 2 μm to 30 μm, more preferably 3 μm to 20 μm, and even more preferably 5 μm to 18 μm.

[0217] [Laminated wiring board] The laminated wiring board according to the present disclosure has, in this order, a first metal layer, a film according to the present disclosure (first film), metal wiring, a film according to the present disclosure (second film), and a second metal layer, and it is preferable that the metal wiring is embedded in a portion of the first film and the second film.

[0218] The film according to the present disclosure has excellent conformability to unevenness, and therefore the laminated wiring board according to the present disclosure is less likely to have gaps between the film and the metal wiring, resulting in low transmission loss.

[0219] Layers A and B included in the first film are preferably formed in the order of layer B, layer A from the side in contact with the metal wiring. Layers A and B included in the second film are preferably formed in the order of layer B, layer A from the side in contact with the metal wiring. When the first film includes layer C, layers A, B, and C included in the first film are preferably formed in the order of layer B, layer A, layer C from the side in contact with the metal wiring. When the second film includes layer C, layers A, B, and C included in the second film are preferably formed in the order of layer B, layer A, layer C from the side in contact with the metal wiring.

[0220] When Layer B is formed on the side in contact with the metal wiring, it is preferable that the metal wiring is embedded in Layer B of each of the first film and the second film. Alternatively, the metal wiring may be embedded in Layer B of each of the first film and the second film, and further embedded in Layer A.

[0221] Details of the first metal layer and the second metal layer are as described in the laminate section. Details of the first film and the second film are as described in the film section. Details of the metal wiring are as described in the wiring substrate section.

[0222] [Method for manufacturing laminated wiring board] The method for manufacturing a laminated wiring board according to the present disclosure preferably includes the steps of: preparing a laminate having a film according to the present disclosure (first film) and a first metal layer disposed on one surface of the first film; preparing a wiring board having a film according to the present disclosure (second film), metal wiring disposed on one surface of the second film, and a second metal layer disposed on the other surface of the second film; and overlapping the laminate and the wiring board so that the first metal layer and the second metal layer are both on the outermost surface, and thermocompression bonding them.

[0223] The details of the process for producing the laminate are as explained in the section on laminate. The details of the process for producing the wiring board are as explained in the section on wiring board.

[0224] The method and conditions for thermocompression bonding the laminate and the wired substrate are not particularly limited and may be appropriately selected from known methods and conditions. The thermocompression temperature is preferably 100°C to 300°C, more preferably 140°C to 200°C. The thermocompression pressure is preferably 0.1 MPa to 20 MPa. The thermocompression treatment time is preferably 0.001 hours to 1.5 hours.

[0225] The present disclosure will be explained in more detail below with reference to examples. The materials, amounts used, ratios, processing details, processing procedures, etc. shown in the following examples can be changed as appropriate without departing from the spirit of the present disclosure. Therefore, the scope of the present disclosure is not limited to the specific examples shown below. In the examples, "%" and "parts" mean "% by mass" and "parts by mass," respectively, unless otherwise specified.

[0226] <Raw materials for forming layer A> LCP1: liquid crystal polymer (product name "Xydar LF31", manufactured by ENEOS Corporation) LCP2: liquid crystal polymer (product name "LAPEROS A-950", manufactured by Polyplastics Co., Ltd.) PE1: low-density polyethylene (product name "Novatec LD", manufactured by Japan Polyethylene Co., Ltd.) Compatibilizer: epoxy group-containing polyolefin copolymer (product name "Bondfast E", manufactured by Sumitomo Chemical Co., Ltd.) PI4: polyimide (product name "Kapton EN", manufactured by Toray Industries, Inc.)

[0227] <Composition for forming layer B, composition for forming layer C> PI3: polyimide (product name "PIAD200", manufactured by Arakawa Chemical Industries, Ltd.) SEBS: styrene-ethylene-butylene-styrene copolymer (product name "Tuftec M1913", manufactured by Asahi Kasei Corporation) PE2: (product name "Novatec HD", manufactured by Japan Polyethylene Corporation) Epoxy compound: N,N-diglycidyl-4-glycidyloxyaniline (manufactured by Sigma-Aldrich Co., Ltd.) Silica particles: product name "Admafine", manufactured by Admatechs Co., Ltd. Solvent: toluene

[0228] Example 1 Preparation of Layer A LCP1, PE1, and a compatibilizer were fed into the cylinder of a single-screw extruder with a screw diameter of 60 mm through a feed port and heated and kneaded. The molten raw materials were extruded as a film from a die with a die width of 750 mm onto a rotating cast roll, cooled and solidified, and stretched as desired to obtain a molded article with a thickness of 40 μm. The LCP1 content of the raw materials was 85% by mass, the PE1 content was 12% by mass, and the compatibilizer content was 3% by mass. The heat-kneading temperature, the discharge speed when discharging the raw materials, the die lip clearance, and the peripheral speed of the cast roll were each adjusted within the following ranges. Heat-kneading temperature: 270 to 350°C Clearance: 0.01 to 5 mm Discharge speed: 0.1 to 1000 mm / sec Peripheral speed of the cast roll: 0.1 to 50 m / min

[0229] The obtained compact was then introduced into a hot air drying oven set at 270°C and heated for 10 hours, thereby carrying out an annealing treatment of the compact. The annealed compact was conveyed while being guided by rollers and taken up by nip rollers to obtain a compact (layer A). A discharge amount of 1500 W min / m was applied to both sides of the compact (layer A). ２ Corona treatment was carried out under the conditions

[0230] [Formation of Layer B] PI3, an epoxy compound, and a solvent were mixed and stirred to obtain a composition B1. The amount of solvent was adjusted so that the solids concentration was 15% by mass. The content of the epoxy compound was adjusted so that it was 5% by mass of the solids content of the composition B1, and this is shown as "epoxy (5)" in Table 1. The obtained composition B1 was applied to one side of the corona-treated molded body (layer A) using an applicator (clearance: 250 μm) to form a coating film. The coating film was dried at 130°C for 1 hour. The application of composition B1 and the drying of the coating film were repeated to form a layer B with a thickness of 5 μm.

[0231] [Formation of Layer C] PI3, an epoxy compound, and a solvent were mixed and stirred to obtain composition C1 in the same manner as composition B1. The obtained composition C1 was applied to the surface of the corona-treated molded body (layer A) opposite to the side on which layer B was formed using an applicator (clearance: 250 μm) to form a coating film. The coating film was dried at 130°C for 1 hour. The application of composition C1 and the drying of the coating film were repeated to form layer C with a thickness of 5 μm. This resulted in a film precursor having layer C, layer A, and layer B in this order.

[0232] Two of the above film precursors were prepared.

[0233] [Preparation of Laminate (Single-Sided Copper-Clad Laminate)] A rolled copper foil (thickness 18 μm, surface roughness Ra 0.9 μm) was laminated to the surface of the film precursor on the Layer C side, and the foil was pressed at 180° C. and 2 MPa for 1 hour using a hot press (Toyo Seiki Seisaku-sho, Ltd.) to prepare a laminate (single-sided copper-clad laminate). The prepared laminate was a laminate having a film having Layer C, Layer A, and Layer B in this order, and a copper layer disposed on Layer C of the film.

[0234] [Preparation of Laminate (Double-Sided Copper-Clad Laminate)] Rolled copper foil (thickness 18 μm, surface roughness Ra 0.9 μm) was laminated to both sides (the surface on the Layer A side and the surface on the Layer C side) of the film precursor, and pressed at 180° C. and 2 MPa for 1 hour using a hot press (Toyo Seiki Seisaku-sho, Ltd.) to prepare a laminate (double-sided copper-clad laminate). The prepared laminate was a laminate having a film having Layer C, Layer A, and Layer B in this order, and copper layers disposed on Layer A and Layer C of the film, respectively.

[0235] [Fabrication of wiring board] A mask layer was laminated on the surface of the copper layer located on the layer B side of the film in the double-sided copper clad laminate. The mask layer was pattern-exposed and then developed to form a mask pattern. Only the surface on the mask pattern side was immersed in a 40% aqueous solution of iron (III) chloride (Fujifilm Wako Pure Chemical Industries, Ltd., Grade 1), and the copper layer on which the mask pattern was not laminated was etched. The mask pattern was then peeled off to form copper wiring (microstrip line). The copper wiring had a length of 10 cm, a width of 100 μm, and a wiring distance of 100 μm. This resulted in a wiring board having a film having layers C, A, and B in this order, a copper layer located on layer C of the film, and copper wiring located on layer B of the film.

[0236] [Preparation of Laminated Wiring Board] The laminate (single-sided copper clad laminate) and the wiring board were superposed and subjected to thermocompression bonding for 3 minutes under conditions of 180°C and 4 MPa. At this time, the copper layer of the laminate (single-sided copper clad laminate) and the copper layer of the wiring board were superposed so that they were both on the outermost surface. This resulted in a laminated wiring board having, in this order, a copper layer, a film (layer C, layer A, and layer B laminated in this order), copper wiring, a film (layer B, layer A, and layer C laminated in this order), and a copper layer. The copper wiring was embedded in part of the two films.

[0237] [Examples 3, 5 to 8, 11 and 12] A laminated wiring substrate was obtained in the same manner as in Example 1, except that the type of raw material for forming Layer A, the type of components in the composition for forming Layer B, and the thicknesses of Layer A and Layer B were changed to those shown in Table 1.

[0238] Example 2 A laminated wiring board was produced in the same manner as in Example 1, except that the formation of Layer B was changed to the method shown below. In forming Layer B, PI, an epoxy compound, and a solvent were mixed and stirred to obtain Composition B2. The amount of solvent was adjusted so that the solids concentration was 15 mass %. The content of the epoxy compound was adjusted so that it was 15 mass % of the solids of Composition B2, and this is shown as "Epoxy (15)" in Table 1.

[0239] Example 4 A laminated wiring substrate was produced in the same manner as in Example 1, except that the formation of Layer B was changed to the method described below. In forming Layer B, PI3, an epoxy compound, silica particles, and a solvent were mixed and stirred to obtain Composition B3. The amount of solvent was adjusted so that the solids concentration was 15% by mass. The content of the epoxy compound was adjusted to 5% by mass of the solids of Composition B3, and the content of the silica particles was adjusted to 20% by mass of the solids of Composition B3.

[0240] [Examples 9 and 10] Laminated wiring boards were produced in the same manner as in Example 1, except that layer C was not formed. First, a film precursor having layers A and B was obtained without forming layer C. A laminate (single-sided copper-clad laminate) was obtained, including a film having layers A and B and a copper layer disposed on layer A of the film. A laminate (double-sided copper-clad laminate) was also obtained, including a film having layers A and B and copper layers disposed on layers A and B of the film, respectively. Furthermore, a wiring board was obtained, including a film having layers A and B in this order, a copper layer disposed on layer A of the film, and copper wiring disposed on layer B of the film. A laminated wiring board was obtained, including a copper layer, a film (layers A and B laminated in this order), copper wiring, a film (layers B and A laminated in this order), and a copper layer, in this order. The copper wiring was embedded in parts of the two films.

[0241] [Comparative Examples 1 to 3] In Comparative Examples 1 to 3, a film precursor having only Layer A was obtained by the same method as in Example 1. However, the adhesion between the film precursor and the metal layer was insufficient, making it impossible to perform wiring processing, and evaluation of step conformability and wiring misalignment was not possible. Therefore, in Table 1, the step conformability and wiring misalignment columns are marked with "-". In Comparative Example 1, when the film precursor and rolled copper foil were bonded at 320°C, wiring processing was possible, but distortion occurred in the wiring.

[0242] Comparative Example 4 A laminated wiring substrate was produced in the same manner as in Example 1, except that the formation of Layer B was changed to the method shown below. In the formation of Layer B, PE2 and a solvent were mixed and stirred to obtain Composition B4. The amount of the solvent was adjusted so that the solids concentration was 15 mass %.

[0243] Comparative Example 5 A laminated wiring substrate was produced in the same manner as in Example 1, except that the formation of Layer A and Layer B was changed to the following method. In forming Layer A, PI4 was used as the raw material for forming Layer A. In forming Layer B, a bonding sheet (product name "NIKAFLEX", manufactured by Nikkan Industries Co., Ltd., "BS" in Table 1) was used.

[0244] The elastic modulus of Layer A and Layer B at 160°C and the dielectric loss tangent of the film were measured using the produced laminate and laminated wiring board, and the step conformability, wiring misalignment, and adhesion were evaluated. The measurement and evaluation methods were as follows.

[0245] <Elastic Modulus of Layer A and Layer B at 160°C> The prepared laminate was cut along the thickness direction to obtain a cut surface. The elastic modulus of each layer at the cut surface of the laminate, at a midpoint in the thickness direction from one surface to the other, was measured by nanoindentation while heating to 160°C using a heater attached to the nanoindenter described below. The elastic modulus was measured at 10 points per position using a nanoindenter ("TI-950", manufactured by HYSITRON) and a Berkovich indenter under the following conditions: load 500 μN, load time 10 seconds, hold time 5 seconds, and unload time 10 seconds. The arithmetic mean value of the 10 points was taken as the elastic modulus (unit: MPa).

[0246] <Dielectric Loss Tangent of Film> The laminate (single-sided copper-clad laminate) was immersed in a 40% aqueous solution of iron (III) chloride (Fujifilm Wako Pure Chemical Industries, Ltd., Grade 1), and the metal layer was dissolved by etching to obtain a film. The dielectric loss tangent was measured at a frequency of 10 GHz using a resonance perturbation method. A 10 GHz cavity resonator (Kanto Electronics Application Development Co., Ltd. CP531) was connected to a network analyzer (Agilent Technology Corporation "E8363B"), and the film (width: 2.0 mm x length: 80 mm) was inserted into the cavity. The dielectric loss tangent of the film was measured from the change in resonance frequency before and after insertion for 96 hours under a temperature of 25°C and a humidity of 60% RH environment.

[0247] <Conformability to Steps> The laminated wiring board was cut in the thickness direction using a microtome, and the cross section was observed using an optical microscope. The presence or absence of gaps between the copper wiring and the film was visually observed. Furthermore, the thickness of Layer A in the laminate (double-sided copper-clad laminate) was evaluated for conformability to steps based on the degree of dimensional change before and after the laminated wiring board was fabricated. The evaluation criteria were as follows: Dimensional change = absolute value of {[thickness of Layer A in the laminate (double-sided copper-clad laminate)] - [thickness of Layer A after the laminated wiring board was fabricated]} A: There was no gap between the copper wiring and the film, and the degree of dimensional change was 2 μm or less. B: There was no gap between the copper wiring and the film, and the degree of dimensional change was more than 2 μm and 5 μm or less. C: There was a gap between the copper wiring and the film. <Wiring Misalignment> The laminated wiring board was cut so as to form a cross section that included the stacking direction and was perpendicular to the longitudinal direction of each copper wiring. The obtained cut surface was observed using an optical microscope (Keyence Corporation's "VHX8000"). Wiring misalignment was evaluated based on the distance M between the center position in the stacking direction of the multilayer wiring substrate and the position of the copper wiring. The position of the copper wiring refers to the center position in the thickness direction of the copper wiring. The evaluation criteria are as follows: A: The distance M is 1 μm or less. B: The distance M is more than 1 μm and less than 3 μm. C: The distance M is more than 3 μm and less than 10 μm. D: The orientation of multiple copper wirings is random.

[0248] <Adhesion> A 1.0 cm wide peel test piece was prepared from the laminate (single-sided copper-clad laminate), and the film was fixed to a flat plate with double-sided adhesive tape. The strength (peel strength) when the film was peeled from the metal layer at a rate of 50 mm / min using the 180° method in accordance with JIS C 5016 (1994) was measured. The adhesion was evaluated based on the peel strength. A: Peel strength is 9 N / cm or more. B: Peel strength is 7 N / cm or more but less than 9 N / cm. C: Peel strength is 1 N / cm or more but less than 7 N / cm. D: Peel strength is less than 1 N / cm.

[0249] The measurement results and evaluation results are shown in Table 1.

[0250] As shown in Table 1, Examples 1 to 12 each include a layer A and a layer B disposed on at least one surface of the layer A, and the ratio of the modulus of elasticity EB of the layer B at 160°C to the modulus of elasticity EA of the layer A at 160°C is 1.0 × 10 －６ As described above, since the dielectric loss tangent was 0.005 or less, it was found that the dielectric loss tangent was low and the step-following property was excellent.

[0251] On the other hand, in Comparative Examples 1 to 3, since Layer B was not included, wiring processing could not be performed as described above.

[0252] In Comparative Example 4, the ratio of the elastic modulus EB of Layer B at 160°C to the elastic modulus EA of Layer A at 160°C was 1.0 × 10 －６ It was found that the step-following ability was poor.

[0253] In Comparative Example 5, the use of a bonding sheet provided conformability to unevenness, but the dielectric loss tangent was very high.

[0254] The disclosure of Japanese Patent Application No. 2022-087675, filed on May 30, 2022, is incorporated herein by reference in its entirety. In addition, all documents, patent applications, and technical standards described herein are incorporated herein by reference to the same extent as if each individual document, patent application, and technical standard were specifically and individually indicated to be incorporated by reference.

Claims

1. A layer A and a layer B disposed on at least one surface of the layer A, The layer A contains a liquid crystal polymer, The ratio of the elastic modulus EB of the layer B at 160° C. to the elastic modulus EA of the layer A at 160° C. is 1.0×10 －６ That's all. A film having a dielectric loss tangent of 0.005 or less.

2. 2. The film of claim 1, wherein the elastic modulus, EB, is less than or equal to 0.1 GPa.

3. 2. The film of claim 1, wherein the ratio of the elastic modulus EB to the elastic modulus EA is less than or equal to 0.

1.

4. 2. The film of claim 1, wherein the average thickness of Layer B is 15 μm or less.

5. 2. The film of claim 1, wherein the melting point of Layer A is 315°C or higher.

6. The film of claim 1 , wherein the Layer A comprises a polyolefin.

7. The film according to claim 6, wherein the content of the polyolefin is 5% by mass to 30% by mass, based on the total mass of the layer A.

8. The film according to claim 1 , wherein the layer B comprises a cured product of a composition comprising a polymer and a compound having a reactive group.

9. Further comprising a layer C, The film of claim 1 , wherein the layer C, the layer A, and the layer B are disposed in this order.

10. 10. The film of claim 9, wherein the average thickness of Layer C is 15 μm or less.

11. The film according to claim 9 , wherein the layer C comprises a cured product of a polymer and a compound having a reactive group.

12. The film according to any one of claims 1 to 11, and a metal layer disposed on at least one surface of the film.

13. The film according to any one of claims 1 to 11, a metal trace disposed on one surface of the film; and a metal layer disposed on the other surface of the film.

14. a first metal layer; A first film according to any one of claims 1 to 11, Metal wiring, A second film according to any one of claims 1 to 11; a second metal layer, The metal wiring is embedded in a portion of the first film and the second film.

15. A step of preparing a laminate having a first film according to any one of claims 1 to 11 and a first metal layer disposed on one surface of the first film; A process for producing a wiring board having the second film according to any one of claims 1 to 11, metal wiring disposed on one surface of the second film, and a second metal layer disposed on the other surface of the second film; a step of laminating the laminate and the wiring board so that the first metal layer and the second metal layer are both on the outermost surface, and thermocompression bonding the laminate and the wiring board; A method for manufacturing a laminated wiring board comprising the steps of: