Liquid dispersion, film, multilayer body, wiring board, and method for producing liquid dispersion

Abstract

Disclosed are: a liquid dispersion which contains a polymer A that has an elastic modulus of more than 0.10 MPa at 260°C, particles which contain a polymer B that has an elastic modulus of 0.10 MPa or less at 260°C, and a solvent, wherein the viscosity η2 at a shear rate of 100 / s at 25°C is 800 mPa∙s or more, and the ratio η1 / η2 of the viscosity η1 at a shear rate of 0.1 / s at 25°C to the viscosity η2 at a shear rate of 100 / s at 25°C is 10 or more; and applications of the liquid dispersion.

Description

Dispersion, film, laminate, wiring board, and method for producing dispersion

[0001] The present disclosure relates to a dispersion, a film, a laminate, a wiring board, and a method for producing the dispersion.

[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 has become necessary to lower the relative permittivity and dielectric loss tangent of insulating materials used in circuit boards. Copper-clad laminates are preferably used as components constituting circuit boards, and films are preferably used to manufacture copper-clad laminates.

[0003] For example, WO 2022 / 163776 describes a polymer film having a layer A and a layer B on at least one surface of the layer A, wherein the layer A contains a polymer having a dielectric loss tangent of 0.01 or less, and the layer B contains an additive, and the layer B has an inflection point in the change in elastic modulus with temperature change or deformation rate change, or the elastic modulus decreases under pressure.Patent Document 2 describes a liquid crystal polymer film containing a liquid crystal polymer component and at least one component selected from the group consisting of an olefin component, a crosslinking component, and a compatible component.

[0004] Typically, copper-clad laminates are manufactured by laminating copper foil on the surface of a polymer film. Furthermore, wiring boards are manufactured by overlapping a copper-clad laminate and a wiring substrate so that the polymer film in the copper-clad laminate contacts the wiring substrate. When manufacturing a wiring board, from the viewpoint of adhesion, it is required that the polymer film conforms to and deforms to the steps formed on the surface of the wiring substrate. On the other hand, when a polymer film with excellent step conformability to the wiring substrate is used in a copper-clad laminate, delamination may occur during the reflow soldering process performed when mounting electronic components. Therefore, there has been a demand for both step conformability to the wiring substrate and excellent adhesion (i.e., excellent heat resistance) during reflow soldering.

[0005] An object of the present disclosure is to provide a dispersion capable of producing a film having excellent step conformability and heat resistance, and a method for producing the dispersion. An object of the present disclosure is to provide a film, a laminate, and a wiring board having excellent step conformability and heat resistance.

[0006] Means for solving the above problems include the following aspects. <1> A dispersion containing particles including a polymer A having an elastic modulus of more than 0.10 MPa at 260°C, a polymer B having an elastic modulus of 0.10 MPa or less at 260°C, and a solvent, wherein the dispersion has a viscosity η2 at a shear rate of 100 / s at 25°C of 800 mPa·s or more, and a ratio η1 / η2 of the viscosity η1 at a shear rate of 0.1 / s at 25°C to the viscosity η2 at a shear rate of 100 / s at 25°C of 10 or more. <2> The dispersion according to <1>, wherein the polymer B has a weight-average molecular weight of 1,000 or more. <3> The dispersion according to <1> or <2>, wherein the polymer B is a thermoplastic elastomer. <4> The dispersion according to <3>, wherein the thermoplastic elastomer is an elastomer containing a structural unit derived from styrene. <5> The dispersion according to <3>, wherein the thermoplastic elastomer is at least one selected from the group consisting of a styrene-ethylene-butylene-styrene block copolymer, a styrene-isobutylene-styrene block copolymer, a styrene-ethylene-propylene-styrene copolymer, a styrene-isoprene-styrene block copolymer, and hydrogenated products thereof. <6> The dispersion according to any one of <1> to <5>, wherein the ratio of the content of particles containing polymer B to the content of polymer A is 1 or more. <7> A film, which is a dried product of the dispersion according to any one of <1> to <6>. <8> A film having a phase-separated structure including at least two phases, wherein the modulus of elasticity at 160°C is 0.60 MPa or less, the modulus of elasticity G1 at 260°C of at least one of the two first phases is more than 0.10 MPa, and the modulus of elasticity G2 at 260°C of a second phase different from the first phase is 0.10 MPa or less, and in a cross section along the thickness direction of the film, the number of regions in the continuous structure of the first phase having a maximum length of 10 μm or less is 0.02 / μm ２or more. <9> The film according to <8>, wherein the second phase contains a polymer having a weight-average molecular weight of 1,000 or more. <10> The film according to <9>, wherein the polymer having a weight-average molecular weight of 1,000 or more is a thermoplastic elastomer. <11> The film according to <10>, wherein the thermoplastic elastomer is an elastomer containing a structural unit derived from styrene. <12> The film according to <10>, wherein the thermoplastic elastomer is at least one selected from the group consisting of a styrene-ethylene-butylene-styrene block copolymer, a styrene-isobutylene-styrene block copolymer, a styrene-ethylene-propylene-styrene copolymer, a styrene-isoprene-styrene block copolymer, and hydrogenated products thereof. <13> The film according to any one of <8> to <12>, wherein the proportion of the second phase is 50 area % or more in a cross section along the thickness direction of the film. <14> A polymer film comprising a layer A and a layer B disposed on at least one surface of the layer A, wherein the layer B has a phase-separated structure including at least two phases, the layer B has an elastic modulus of 0.60 MPa or less at 160°C, a first phase which is one of the at least two phases has an elastic modulus G1 at 260°C of more than 0.10 MPa, and a second phase different from the first phase has an elastic modulus G2 at 260°C of 0.10 MPa or less, and in a cross section along the thickness direction of the layer B, the number of regions in the continuous structure of the first phase which have a maximum length of 10 μm or less is 0.02 / μm ２ <15> The laminate according to <14>, wherein Layer A contains a liquid crystal polymer. <16> A laminate comprising: a substrate, a wiring pattern disposed on at least one surface of the substrate, Layer B disposed between the wiring patterns and on the wiring pattern, and Layer A disposed on Layer B, wherein Layer B has a phase-separated structure containing at least two phases, and Layer B has an elastic modulus at 160°C of 0.60 MPa or less, a first phase which is one of the at least two phases has an elastic modulus G1 at 260°C of more than 0.10 MPa, and a second phase different from the first phase has an elastic modulus G2 at 260°C of 0.10 MPa or less, and in a cross section along the thickness direction of Layer B, the number of regions in the continuous structure of the first phase which have a maximum length of 10 μm or less is 0.02 / μm２ <17> A method for producing a dispersion, comprising: mixing a polymer A having an elastic modulus of more than 0.10 MPa at 260°C, particles containing a polymer B having an elastic modulus of 0.10 MPa or less at 260°C, and a solvent; and subjecting the mixture to a bead mill treatment for 5 to 60 minutes.

[0007] According to an embodiment of the present disclosure, a dispersion capable of obtaining a film having excellent step conformability and heat resistance, and a method for manufacturing the dispersion are provided. According to an embodiment of the present disclosure, a film, a laminate, and a wiring board having excellent step conformability and heat resistance are provided.

[0008] The contents of the present disclosure are described in detail below. The following description of the constituent elements may be based on a representative embodiment of the present disclosure, but the present disclosure is not limited to such an embodiment. In this specification, 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 this disclosure, the upper or lower limit of 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 this disclosure, the upper or lower limit of that numerical range may be replaced with a value shown in the examples. Furthermore, in the description of groups (atomic groups) in this specification, a notation that does not specify whether they are substituted or unsubstituted encompasses both unsubstituted and substituted groups. For example, the term "alkyl group" encompasses not only alkyl groups without substituents (unsubstituted alkyl groups) but also alkyl groups with substituents (substituted alkyl groups). In this specification, "(meth)acrylic" is a term used to conceptually encompass both acrylic and methacrylic, and "(meth)acryloyl" is a term used to conceptually encompass both acryloyl and methacryloyl. Furthermore, the term "process" in this specification 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 this disclosure, a combination of two or more preferred aspects is a more preferred aspect. Furthermore, unless otherwise specified, the weight-average molecular weight (Mw) and number-average molecular weight (Mn) in this disclosure are molecular weights determined by a gel permeation chromatography (GPC) analyzer using a TSKgel Super HM-H (trade name of Tosoh Corporation) column, a PFP (pentafluorophenol) / chloroform solvent (mass ratio) = 1 / 2, a differential refractometer, and conversion using polystyrene as a standard substance.

[0009] [Dispersion] The dispersion according to the present disclosure contains particles including a polymer A having an elastic modulus of more than 0.10 MPa at 260°C and a polymer B having an elastic modulus of 0.10 MPa or less at 260°C, and a solvent, and has a viscosity η2 at a shear rate of 100 / s at 25°C of 800 mPa·s or more, and a ratio η1 / η2 of the viscosity η1 at a shear rate of 0.1 / s at 25°C to the viscosity η2 at a shear rate of 100 / s at 25°C of 10 or more.

[0010] As a result of extensive investigations, the present inventors have found that by adopting the above-mentioned constitution, it is possible to provide a dispersion liquid capable of producing a film having excellent step-conforming ability and heat resistance. Although the detailed mechanism by which the above-mentioned effects are obtained is unknown, it is speculated as follows.

[0011] When manufacturing a multilayer copper-clad laminate, copper foil and a film are laminated together and then thermocompression bonded. During this process, heating causes some of the materials contained in the film to become more fluid. During thermocompression bonding, some of the fluid materials may migrate within the film. This migration causes the fluid materials to aggregate. In the reflow soldering process performed when mounting electronic components, the film is heated at high temperatures (e.g., 260°C). During this process, it is believed that water present in the film becomes supersaturated and diffuses, causing bubble nuclei to form in the aggregated portions of the fluid materials. Conventionally, bubble nuclei have grown and foamed, sometimes resulting in delamination between the film and the metal layer. In contrast, the dispersion according to the present disclosure has a viscosity η2 at a shear rate of 100 / s at 25°C of 800 mPa·s or more, and the ratio η1 / η2 of the viscosity η1 at a shear rate of 0.1 / s at 25°C to the viscosity η2 at a shear rate of 100 / s at 25°C is 10 or more. When the ratio η1 / η2 is 10 or more, particles containing polymer B exist finer in the dispersion without forming aggregates, resulting in excellent dispersibility. During thermocompression bonding, the phase derived from polymer B, which has low fluidity, does not exist continuously, thereby suppressing localized flow. It is believed that the generation and growth of bubble nuclei during the reflow soldering process is suppressed, resulting in suppression of peeling between the film and the metal layer. In other words, the film has excellent heat resistance.

[0012] In contrast, WO 2022 / 163776 does not include any description focusing on the viscosity of the dispersion.

[0013] The dispersion according to the present disclosure will be described in detail below.

[0014] The dispersion according to the present disclosure contains particles including polymer A having an elastic modulus of more than 0.10 MPa at 260°C and polymer B having an elastic modulus of 0.10 MPa or less at 260°C, and a solvent.

[0015] <Polymer A> Polymer A has an elastic modulus at 260°C of more than 0.10 MPa.

[0016] In the present disclosure, the elastic modulus of polymer A at 260°C is measured by the following method. The elastic modulus of polymer A at 260°C is measured as the indentation elastic modulus using a nanoindentation method. The indentation elastic modulus is measured using a microhardness tester (for example, product name "DUH-W201" manufactured by Shimadzu Corporation) by applying a load with a Vickers indenter at a loading rate of 0.28 mN / sec, holding a maximum load of 10 mN for 10 seconds, and then unloading at a loading rate of 0.28 mN / sec.

[0017] From the viewpoint of heat resistance, the elastic modulus of polymer A at 260°C is preferably 0.15 MPa or more, more preferably 0.5 MPa or more, and even more preferably 1.0 MPa or more. The upper limit of the elastic modulus of polymer A at 260°C is not particularly limited, and is, for example, 1000 MPa. When the elastic modulus of polymer A at 260°C exceeds 0.10 MPa, the heat resistance is excellent.

[0018] Examples of polymer A include liquid crystal polymers, fluororesins, polymers of compounds having a cyclic aliphatic hydrocarbon group and a group having an ethylenically unsaturated bond, polyphenylene ethers and modified products thereof, aromatic polyether ketones, phenolic resins, epoxy resins, polyimides, cyanate resins, bismaleimide resins, triazine resins, and other thermosetting resins.

[0019] - Liquid Crystal Polymer - From the viewpoint of dielectric loss tangent, polymer A preferably contains a liquid crystal polymer.

[0020] 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.

[0021] 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.

[0022] 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.

[0023] 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.

[0024] The liquid crystal polymer is preferably a wholly aromatic liquid crystal polymer made using only aromatic compounds as raw material monomers.

[0025] 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.

[0026] The melting point of the liquid crystal polymer is preferably higher than 260°C, more preferably higher than 260°C and not higher than 350°C, and even more preferably higher than 260°C and not higher than 330°C.

[0027] In the present disclosure, the melting point is measured using a differential scanning calorimeter. For example, it is measured using a product called "DSC-60A Plus" (manufactured by Shimadzu Corporation). The temperature rise rate in the measurement is 10°C / min.

[0028] 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.

[0029] 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 is preferably a wholly aromatic polyesteramide.

[0030] The aromatic polyesteramide is preferably a crystalline polymer. Polymer A preferably contains a crystalline aromatic polyesteramide. The crystalline aromatic polyesteramide further reduces the dielectric loss tangent. A crystalline polymer refers to a polymer that has a clear endothermic peak rather than a stepwise change in endothermic amount in differential scanning calorimetry (DSC). Specifically, for example, this means that the half-width of the endothermic peak when measured at a heating rate of 10°C / min is within 10°C. Polymers with a half-width exceeding 10°C and polymers in which no clear endothermic peak is observed are considered amorphous polymers and are distinguished from crystalline polymers.

[0031] 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.

[0032] 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.

[0033] 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.

[0034] 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.

[0035] 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.

[0036] 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.

[0037] 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.

[0038] 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.

[0039] In formula 3, Ar ３ is preferably a p-phenylene group or a 4,4'-biphenylylene group, and more preferably a p-phenylene group.

[0040] 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.

[0041] 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.

[0042] 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.

[0043] 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.

[0044] The aromatic polyesteramide is preferably produced by melt-polymerizing raw material monomers corresponding to the structural units that constitute the aromatic polyesteramide.

[0045] The weight average molecular weight of the aromatic polyesteramide 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.

[0046] -Fluororesin- From the viewpoint of heat resistance and mechanical strength, the polymer A may be a fluororesin.

[0047] In the present disclosure, the type of fluororesin is not particularly limited, and known fluororesins can be used.

[0048] 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.

[0049] 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.

[0050] 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.

[0051] 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.

[0052] 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.

[0053] 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.

[0054] 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.

[0055] 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.

[0056] —Polymer of a Compound Having a Cyclic Aliphatic Hydrocarbon Group and a Group Having an Ethylenically Unsaturated Bond— Polymer A may be a polymer of a compound having a cyclic aliphatic hydrocarbon group and a group having an ethylenically unsaturated bond.

[0057] Examples of polymers of compounds having a cyclic aliphatic 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.

[0058] The polymer of a compound having a cyclic aliphatic hydrocarbon group and a group having an ethylenically unsaturated bond may be a ring-opening polymer of the above-mentioned cyclic olefin or a hydrogenated product of a ring-opening copolymer using two or more kinds of cyclic olefins, or may be an addition polymer of a cyclic olefin and an aromatic compound having an ethylenically unsaturated bond such as a chain olefin or a vinyl group. In addition, a polar group may be introduced into the polymer of a compound having a cyclic aliphatic hydrocarbon group and a group having an ethylenically unsaturated bond.

[0059] The polymer of a compound having a cyclic aliphatic hydrocarbon group and a group having an ethylenically unsaturated bond may be used alone or in combination of two or more kinds.

[0060] 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 isophorone 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.

[0061] -Polyphenylene Ether- Polymer A may be 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.

[0062] 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).

[0063]

[0064] 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.

[0065] When the polyphenylene ether is heat-cured after film formation, the weight-average molecular weight (Mw) is preferably 500 to 5,000, more preferably 500 to 3,000, from the viewpoints of heat resistance and film formability. When the polyphenylene ether is not heat-cured, the weight-average molecular weight (Mw) is not particularly limited, but is preferably 3,000 to 100,000, more preferably 5,000 to 50,000.

[0066] - Aromatic Polyether Ketone - Polymer A may be an aromatic polyether ketone.

[0067] The aromatic polyether ketone is not particularly limited, and any known aromatic polyether ketone can be used.

[0068] The aromatic polyether ketone is preferably polyether ether ketone.

[0069] 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. Each bond is preferably connected by a divalent aromatic group. The aromatic polyether ketone may be used alone or in combination of two or more types.

[0070] 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).

[0071]

[0072] 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.

[0073] Among these, from the viewpoint of the dielectric loss tangent, polymer A is preferably at least one selected from the group consisting of a liquid crystal polymer, a polymer of a compound having a cyclic aliphatic hydrocarbon group and a group having an ethylenically unsaturated bond, and a fluororesin, and is more preferably an aromatic polyesteramide.

[0074] <Particles Containing Polymer B> Polymer B has an elastic modulus at 260° C. of 0.10 MPa or less.

[0075] In the present disclosure, the elastic modulus G2 of polymer B at 260°C is measured by the following method. The elastic modulus of polymer B at 260°C is measured as the indentation elastic modulus using a nanoindentation method. The indentation elastic modulus is measured using a microhardness tester (for example, product name "DUH-W201" manufactured by Shimadzu Corporation) by applying a load with a Vickers indenter at a loading rate of 0.28 mN / sec, holding a maximum load of 10 mN for 10 seconds, and then unloading at a loading rate of 0.28 mN / sec.

[0076] From the viewpoint of conformability to uneven surfaces, the elastic modulus of polymer B at 260°C is preferably less than 0.10 MPa, more preferably 0.07 MPa or less, and even more preferably 0.05 MPa or less. The lower limit of the elastic modulus of polymer B at 260°C is not particularly limited and may be, for example, 0.1 kPa. When the elastic modulus of polymer B at 260°C is 0.10 MPa or less, the uneven surface conformability is excellent.

[0077] From the viewpoint of heat resistance, the polymer B preferably has a weight average molecular weight of 1,000 or more.

[0078] The weight average molecular weight of Polymer B is more preferably 10,000 or more, and even more preferably 30,000 or more. The upper limit of the weight average molecular weight is, for example, 1,000,000.

[0079] From the viewpoint of conformability to unevenness, polymer B is preferably a thermoplastic resin, a thermoplastic elastomer, an uncured or semi-cured product of a thermosetting resin, or an uncured or semi-cured product of a thermosetting elastomer.

[0080] Examples of thermoplastic resins include polyurethane resins, polyester resins, (meth)acrylic resins, polystyrene resins, fluororesins, polyimide resins, fluorinated polyimide resins, polyamide resins, polyamideimide resins, polyetherimide resins, cellulose acylate resins, polyurethane resins, polyether ether ketone resins, polycarbonate resins, polyolefin resins (e.g., polyethylene resins, polypropylene resins, resins made of cyclic olefin copolymers, alicyclic polyolefin resins), polyarylate resins, polyethersulfone resins, polysulfone resins, fluorene ring-modified polycarbonate resins, alicyclic modified polycarbonate resins, and fluorene ring-modified polyester resins.

[0081] Examples of thermoplastic elastomers include elastomers containing structural units derived from styrene (polystyrene-based elastomers), polyester-based elastomers, polyolefin-based elastomers, polyurethane-based elastomers, polyamide-based elastomers, polyacrylic-based elastomers, silicone-based elastomers, polyimide-based elastomers, etc. The thermoplastic elastomer may be a hydrogenated product.

[0082] Examples of polystyrene elastomers include styrene-butadiene-styrene block copolymers (SBS), styrene-isoprene-styrene block copolymers (SIS), polystyrene-poly(ethylene-propylene) diblock copolymers (SEP), polystyrene-poly(ethylene-propylene)-polystyrene triblock copolymers (SEPS), styrene-ethylene-butylene-styrene block copolymers (SEBS), and polystyrene-poly(ethylene / ethylene-propylene)-polystyrene triblock copolymers (SEEPS), styrene-isobutylene-styrene block copolymers (SIBS), and hydrogenated products thereof.

[0083] Among these, from the viewpoints of the dielectric loss tangent and the ability to conform to unevenness, polymer B is preferably a thermoplastic elastomer, more preferably an elastomer containing a structural unit derived from styrene, and even more preferably at least one selected from the group consisting of a styrene-ethylene-butylene-styrene block copolymer, a styrene-isobutylene-styrene block copolymer, a styrene-ethylene-propylene-styrene copolymer, a styrene-isoprene-styrene block copolymer, and hydrogenated products thereof.

[0084] In particular, hydrogenated styrene-isobutylene-styrene block copolymers are advantageous in terms of heat resistance because they are less likely to soften at high temperatures (for example, 260° C.).

[0085] The particles containing polymer B may contain components other than polymer B, but preferably do not contain components other than polymer B. In other words, the particles containing polymer B are preferably particles made of polymer B.

[0086] From the viewpoint of heat resistance, the average particle size of the particles containing polymer B is preferably 0.01 μm to 30 μm, and more preferably 0.1 μm to 20 μm. From the viewpoint of heat resistance, the particle size distribution (D90 / D10) of the particles containing polymer B in the dispersion is preferably 1 to 4, and more preferably 1 to 3.

[0087] In the present disclosure, the average particle size (e.g., D50) and particle size distribution (e.g., D90 / D10) of particles are measured using a laser diffraction / scattering particle size distribution analyzer. For example, the LA-950V2 manufactured by HORIBA Corporation is used as the laser diffraction / scattering particle size distribution analyzer.

[0088] From the viewpoint of achieving both step-conforming properties and processability, the ratio of the content of the particles containing polymer B to the content of polymer A is preferably at least 1, more preferably at least 2, and even more preferably at least 3. The upper limit of this ratio is not particularly limited and is, for example, 10.

[0089] <Solvent> The dispersion according to the present disclosure contains a solvent. In the dispersion according to the present disclosure, from the viewpoint of improving the heat resistance of the film, it is preferable that polymer A is dissolved in the solvent and particles containing polymer B are dispersed in the solvent. That is, it is preferable that the solvent is a solvent that dissolves polymer A but does not dissolve polymer B.

[0090] Examples of the solvent include halogenated hydrocarbons such as dichloromethane, chloroform, 1,1-dichloroethane, 1,2-dichloroethane, 1,1,2,2-tetrachloroethane, 1-chlorobutane, chlorobenzene, and o-dichlorobenzene; halogenated phenols such as p-chlorophenol, pentachlorophenol, and pentafluorophenol; ethers such as diethyl ether, tetrahydrofuran, and 1,4-dioxane; ketones such as acetone and cyclohexanone; esters such as ethyl acetate and γ-butyrolactone; and ethylene carbonate. nitriles such as acetonitrile and succinonitrile; amides such as N,N-dimethylformamide, N,N-dimethylacetamide, and N-methylpyrrolidone, and urea compounds such as tetramethylurea; nitro compounds such as nitromethane and nitrobenzene; sulfur compounds such as dimethyl sulfoxide and sulfolane; and phosphorus compounds such as hexamethylphosphoramide and tri-n-butylphosphoric acid, and two or more of these may be used.

[0091] As the solvent, a solvent mainly composed of an aprotic compound, particularly an aprotic compound having no halogen atoms, is preferred because it is less corrosive and easier to handle, and the proportion of the aprotic compound in the entire solvent is preferably 50% by mass to 100% by mass, more preferably 70% by mass to 100% by mass, and particularly preferably 90% by mass to 100% by mass. Furthermore, as the aprotic compound, an amide such as N,N-dimethylformamide, N,N-dimethylacetamide, tetramethylurea, N-methylpyrrolidone, or an ester such as γ-butyrolactone is preferably used because it easily dissolves the liquid crystal polymer, and N,N-dimethylformamide, N,N-dimethylacetamide, and N-methylpyrrolidone are more preferred.

[0092] Furthermore, as the solvent, a solvent containing as a main component a compound having a dipole moment of 3 to 5 is preferred because it easily dissolves polymer A, and the proportion of the compound having a dipole moment of 3 to 5 in the entire solvent is preferably 50% by mass to 100% by mass, more preferably 70% by mass to 100% by mass, and particularly preferably 90% by mass to 100% by mass. It is preferable to use a compound having a dipole moment of 3 to 5 as the aprotic compound.

[0093] Furthermore, as the solvent, a solvent containing as a main component a compound having a boiling point of 220°C or lower at 1 atmosphere is preferred because it is easy to remove, and the proportion of the compound having a boiling point of 220°C or lower at 1 atmosphere in the entire solvent is preferably 50% by mass to 100% by mass, more preferably 70% by mass to 100% by mass, and particularly preferably 90% by mass to 100% by mass. As the aprotic compound, it is preferred to use a compound having a boiling point of 220°C or lower at 1 atmosphere.

[0094] The content of the solvent is not particularly limited, but from the viewpoint of coatability, it is preferably 20% by mass to 90% by mass, and more preferably 30% by mass to 80% by mass, relative to the total amount of the dispersion according to the present disclosure. The dispersion according to the present disclosure may contain other components in addition to the polymer A, the particles containing polymer B, and the solvent.

[0095] Other components that can be used include known additives, such as a leveling agent, an antifoaming agent, an antioxidant, an ultraviolet absorber, a flame retardant, and a colorant.

[0096] The dispersion according to the present disclosure preferably has a solid content concentration of 10% by mass to 80% by mass, more preferably 20% by mass to 70% by mass. In the present disclosure, the solid content refers to components contained in the dispersion other than the solvent.

[0097] The dispersion according to the present disclosure has a viscosity η2 of 800 mPa s or more at a shear rate of 100 / s at 25°C. Because the viscosity η2 is 800 mPa s or more, a film having excellent step-following ability and heat resistance can be obtained. The upper limit of the viscosity η2 is not particularly limited, and is, for example, 10,000 mPa s.

[0098] Furthermore, the dispersion according to the present disclosure has a ratio η1 / η2 of the viscosity η1 at a shear rate of 0.1 / s at 25°C to the viscosity η2 at a shear rate of 100 / s at 25°C, that is, η1 / η2, of 10 or more. Because the ratio η1 / η2 is 10 or more, a film with excellent step-following ability and heat resistance can be obtained. The ratio η1 / η2 is preferably 10 or more, and more preferably 60 or more. The upper limit of the ratio η1 / η2 is not particularly limited, and is, for example, 100.

[0099] In this disclosure, the viscosity is measured at 25° C. using a rheometer (product name “HAAKE MARS40 / 60” manufactured by ThermoFisher Scientific). The viscosity is measured while scanning the frequency from 1000 / s to 0.1 / s.

[0100] For example, the ratio η1 / η2 can be adjusted to a range of 10 or more by adjusting the dispersion conditions, the types of particles containing polymer A and polymer B contained in the dispersion, the type of solvent, and the like.

[0101] [Method for Producing Dispersion] The method for producing a dispersion according to the present disclosure includes the steps of mixing particles containing polymer A having an elastic modulus of more than 0.10 MPa at 260°C and polymer B having an elastic modulus of 0.10 MPa or less at 260°C with a solvent, and subjecting the mixture to a bead mill treatment for 5 to 60 minutes.

[0102] The preferred embodiments of the particles containing polymer A and polymer B are as described above.

[0103] The bead mill treatment can be carried out using a commonly known bead mill disperser.

[0104] Examples of materials for the beads used in bead mill treatment include inorganic compounds such as zirconia, yttria-stabilized zirconia, alumina, steatite, silicon carbide, silicon nitride, silica, sand, agate, steel balls, stainless steel, glass, low-alkali glass, and non-alkali glass; and polymers such as polystyrene, polymethyl methacrylate, polytetrafluoroethylene, polyamide, polyethylene, polypropylene, polyether ether ketone (PEEK), and polyimide. Of these, zirconia is preferred as the material for the beads.

[0105] The bead diameter is not particularly limited, but from the viewpoint of controlling the viscosity, it is preferably 0.5 mm to 5 mm, and more preferably 1 mm to 3 mm.

[0106] The time for the bead mill treatment is 5 to 60 minutes, preferably 5 to 30 minutes, from the viewpoint of controlling the viscosity.

[0107] [Film] The film according to the present disclosure may be a dried product of the dispersion according to the present disclosure. The dried product means a product obtained by drying the dispersion. The content of the solvent contained in the dried product is preferably 1% by mass or less, more preferably 0.1% by mass or less. The film according to the present disclosure is produced, for example, by applying the film according to the present disclosure and drying it.

[0108] The film according to the present disclosure has a phase-separated structure containing at least two phases, and has an elastic modulus at 160°C of 0.60 MPa or less, and the elastic modulus G1 at 260°C of at least one of the two phases, which is a first phase, exceeds 0.10 MPa, and the elastic modulus G2 at 260°C of a second phase different from the first phase, is 0.10 MPa or less, and in a cross section along the thickness direction of the film, the number of regions in the continuous structure of the first phase, which have a maximum length of 10 μm or less, is 0.02 / μm. ２ That's all.

[0109] As a result of intensive research, the present inventors have found that by adopting the above-mentioned configuration, it is possible to provide a film that is excellent in step conformability and heat resistance. The detailed mechanism by which the above-mentioned effects are obtained is unknown, but is presumed as follows. In the film according to the present disclosure, in a cross section along the thickness direction of the film, the number of regions in the continuous structure of the first phase having a maximum length of 10 μm or less is 0.02 / μm. ２ For these reasons, localized flow of the material contained in the film is suppressed during thermocompression bonding. This is thought to suppress the generation and growth of bubble nuclei during the reflow soldering process, thereby suppressing peeling between the film and the metal layer. In other words, the film has excellent heat resistance.

[0110] In contrast, WO 2022 / 163776 does not include any description focusing on the number of regions in the continuous structure of the first phase having a maximum length of 10 μm or less in a cross section along the thickness direction of the film.

[0111] The film according to the present disclosure will be described in detail below.

[0112] The film according to the present disclosure has a phase-separated structure containing at least two phases. In the present disclosure, the term "phase-separated structure" refers to a structure in which the film has at least two parts containing different components.

[0113] Examples of the phase-separated structure include a sea-island structure, a co-continuous structure, a cylindrical structure, and a lamellar structure. Among these, the phase-separated structure in the film according to the present disclosure is preferably a sea-island structure. The sea-island structure refers to a structure in which one of at least two phases forms a continuous phase and the other phase is present in a discontinuously dispersed state.

[0114] The presence of a phase-separated structure can be confirmed by using means such as morphological observation, material distribution evaluation, and mechanical property distribution evaluation on the film surface, film cross section, or both the film surface and cross section. In the present disclosure, if a phase-separated structure can be confirmed by any one of morphological observation, material distribution evaluation, and mechanical property distribution evaluation, it is determined that the film has a phase-separated structure. Morphological observation is performed using a known optical microscope. If observation is not possible using a known optical microscope, it is performed using an electron microscope or the like. Material distribution evaluation is performed using infrared spectroscopy imaging. If infrared spectroscopy imaging is not possible, it is performed using Raman spectroscopy imaging. If Raman spectroscopy imaging is not possible, it is performed using X-ray photoelectron spectroscopy imaging. Mechanical property distribution evaluation is performed using an atomic force microscope or the like.

[0115] <First Phase> The film according to the present disclosure has a phase-separated structure containing at least two phases. One of the at least two phases, the first phase, has an elastic modulus G1 at 260°C of more than 0.10 MPa.

[0116] In the present disclosure, the elastic modulus G1 of the first phase at 260°C is measured by the following method. A film cross-section sample is prepared by obliquely cutting with a microtome so that the cross-section has a thickness of 50 μm. Next, the 260°C elastic modulus of the first phase is measured as the indentation elastic modulus using a nanoindentation method. The indentation elastic modulus is measured using a microhardness tester (for example, product name "DUH-W201" manufactured by Shimadzu Corporation) by applying a load with a Vickers indenter at a loading rate of 0.28 mN / sec, holding a maximum load of 10 mN for 10 seconds, and then unloading at a loading rate of 0.28 mN / sec.

[0117] From the viewpoint of conformability to unevenness, the elastic modulus of the first phase at 260°C is preferably 1.0 MPa or more. The upper limit of the elastic modulus of the first phase at 260°C is not particularly limited, and is, for example, 1000 MPa. When the elastic modulus of the first phase at 260°C exceeds 0.10 MPa, excellent heat resistance is achieved.

[0118] The first phase may be a low molecular weight compound or a high molecular weight compound, provided that the first phase has an elastic modulus at 260°C of more than 0.10 MPa.

[0119] Examples of compounds that constitute the first phase include liquid crystal polymers, fluororesins, polymers of compounds having a cyclic aliphatic hydrocarbon group and a group having an ethylenically unsaturated bond, polyphenylene ether and modified products thereof, aromatic polyether ketone, phenolic resins, epoxy resins, polyimides, cyanate resins, bismaleimide resins, triazine resins, and other thermosetting resins.

[0120] Preferred embodiments of the liquid crystal polymer, the fluororesin, the polymer of a compound having a cyclic aliphatic hydrocarbon group and a group having an ethylenically unsaturated bond, the polyphenylene ether and modified products thereof, and the aromatic polyether ketone are as described above.

[0121] <Second Phase> The film according to the present disclosure has a phase-separated structure including at least two phases. One of the at least two phases, the second phase, which is different from the first phase, has an elastic modulus G2 at 260°C of 0.10 MPa or less.

[0122] In the present disclosure, the elastic modulus G2 of the second phase at 260°C is measured by the following method. A film cross-section sample is prepared by obliquely cutting with a microtome so that the cross-section has a thickness of 50 μm. Next, the 260°C elastic modulus of the second phase is measured as the indentation elastic modulus using a nanoindentation method. The indentation elastic modulus is measured using a microhardness tester (for example, product name "DUH-W201" manufactured by Shimadzu Corporation) by applying a load with a Vickers indenter at a loading rate of 0.28 mN / sec, holding a maximum load of 10 mN for 10 seconds, and then unloading at a loading rate of 0.28 mN / sec.

[0123] From the viewpoint of the ability to conform to uneven surfaces, the elastic modulus of the second phase at 260°C is preferably 0.05 MPa or less. The lower limit of the elastic modulus of the second phase at 260°C is not particularly limited and may be, for example, 0.1 kPa. When the elastic modulus of the second phase at 260°C is 0.10 MPa or less, the ability to conform to uneven surfaces is excellent.

[0124] The second phase may be a low molecular weight compound or a high molecular weight compound, so long as the modulus of elasticity at 260° C. is 0.10 MPa or less.

[0125] From the viewpoint of heat resistance, the second phase preferably contains a polymer having a weight average molecular weight of 1,000 or more.

[0126] The weight-average molecular weight of the polymer contained in the second phase is more preferably 10,000 or more, and even more preferably 30,000 or more. The upper limit of the weight-average molecular weight is, for example, 1,000,000.

[0127] The preferred embodiments of the polymer contained in the second phase are the same as those of the polymer B.

[0128] From the viewpoint of achieving both step-following ability and processability, the proportion of the second phase in the cross section along the thickness direction of the film is preferably 50 area % or more, more preferably 50 area % to 95 area %, and even more preferably 60 area % to 90 area %.

[0129] The film according to the present disclosure has an elastic modulus of 0.60 MPa or less, preferably 0.50 MPa or less, at 160°C. When the elastic modulus is 0.60 MPa or less at 160°C, the film has excellent conformability to unevenness. The lower limit of the elastic modulus at 160°C is not particularly limited, but is 0.001 MPa from the viewpoint of preventing the polymer contained in the second phase from flowing and being extruded out of the system when pressure is applied.

[0130] In the present disclosure, the modulus of elasticity of a film at 160°C is measured by the following method. A film cross-section sample is prepared by obliquely cutting with a microtome so that the cross-section thickness is 50 μm. Next, the modulus of elasticity of the film is measured as the indentation modulus using a nanoindentation method. The indentation modulus is measured using a microhardness tester (for example, product name "DUH-W201" manufactured by Shimadzu Corporation) by applying a load with a Vickers indenter at a loading rate of 0.28 mN / sec, holding a maximum load of 10 mN for 10 seconds, and then unloading at a loading rate of 0.28 mN / sec. Measurements are made at 160°C at 20 random positions on the cross-section sample, and the average value is taken as the modulus of elasticity.

[0131] In the film according to the present disclosure, in a cross section along the thickness direction of the film, the number of regions in the continuous structure of the first phase having a maximum length of 10 μm or less is 0.02 / μm ２ In the continuous structure of the first phase, the number of regions having a maximum length of 10 μm or less is 0.02 / μm ２ If the thickness is above this, localized flow of the material contained in the film is suppressed during thermocompression bonding, and the generation and growth of bubble nuclei is suppressed during the reflow soldering process, resulting in excellent heat resistance.

[0132] From the viewpoint of further improving the heat resistance, the number of regions having a maximum length of 10 μm or less in the continuous structure of the first phase is set to 0.02 / mm ２ It is preferable that the number of particles is 0.05 particles / mm or more. ２ The upper limit of the number is not particularly limited, and is preferably 1.00 pieces / mm ２ may be.

[0133] The number of regions in the continuous structure of the first phase having a maximum length of 10 μm or less is measured by the following method.

[0134] The film is cut in the thickness direction using a cryomicrotome to expose the cross section. The film cross section is observed under an optical microscope. The continuous structure of the first phase is identified from the cross-sectional image. Specifically, an amorphous shape in the first phase, where spherical or elliptical shapes are bonded to each other, is determined to be the continuous structure of the first phase. If it is spherical or elliptical, it is not determined to be the continuous structure of the first phase. The maximum length of the continuous structure of the first phase is measured in any 30 μm × 30 μm region of the cross-sectional image. The number of regions where the maximum length is 10 μm or less is counted. The average number of regions in three regions is calculated. The obtained average is divided by 900 to obtain 1 μm. ２ Convert into the number of pieces per unit.

[0135] The film according to the present disclosure preferably has a dielectric loss tangent of 0.01 or less, more preferably 0.005 or less, and even more preferably greater than 0 and 0.003 or less.

[0136] 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 a resonance perturbation method. A 10 GHz cavity resonator (CP531 manufactured by Kanto Electronics Application Development Co., Ltd.) is connected to a network analyzer (E8363B manufactured by Agilent Technology Corporation), a polymer film is inserted into the cavity resonator, and the dielectric loss tangent 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.

[0137] The 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 60 μm, from the viewpoints of strength, dielectric loss tangent, and adhesion to the metal layer.

[0138] The thickness of the film is measured at any five points using an adhesive film thickness meter, such as an electronic micrometer (product name "KG3001A" manufactured by Anritsu Corporation), and the average value of the measured thicknesses is used.

[0139] [Laminate] A laminate according to the present disclosure includes a layer A and a layer B disposed on at least one surface of the layer A, wherein the layer B has a phase-separated structure including at least two phases, the layer B has an elastic modulus at 160°C of 0.60 MPa or less, the first phase, which is one of the at least two phases, has an elastic modulus G1 at 260°C of more than 0.10 MPa, and the second phase, which is different from the first phase, has an elastic modulus G2 at 260°C of 0.10 MPa or less, and in a cross section along the thickness direction of the layer B, the number of regions in the continuous structure of the first phase, which have a maximum length of 10 μm or less, is 0.02 / μm ２ That's all.

[0140] In the laminate according to the present disclosure, in a cross section along the thickness direction of Layer B, the number of regions in the continuous structure of the first phase having a maximum length of 10 μm or less is 0.02 / μm ２ For these reasons, the film has excellent step-following ability and heat resistance.

[0141] The laminate according to the present disclosure includes a layer A and a layer B disposed on at least one surface of the layer A. The layer A and the layer B may be in direct contact with each other, or another layer may be provided between the layer A and the layer B. From the viewpoint of step-following ability and heat resistance, the layer A and the layer B are preferably in direct contact with each other.

[0142] <<Layer B>> Layer B has a phase-separated structure including at least two phases, in which the elastic modulus G1 at 260°C of a first phase, which is one of the at least two phases, exceeds 0.10 MPa, and the elastic modulus G2 at 260°C of a second phase different from the first phase is 0.10 MPa or less.

[0143] The preferred embodiments of the first and second phases in Layer B are the same as those of the first and second phases in the film.

[0144] The elastic modulus of Layer B at 160° C. is 0.60 MPa or less, and preferably 0.50 MPa or less. When the elastic modulus of Layer B at 160° C. is 0.60 MPa or less, the layer has excellent conformability to unevenness. The lower limit of the elastic modulus of Layer B at 160° C. is not particularly limited, but may be 0.1 kPa from the viewpoint of processability.

[0145] In the present disclosure, the modulus of elasticity of Layer B at 160°C is measured by the following method. A cross-sectional film sample is prepared by obliquely cutting with a microtome so that the cross-sectional thickness is 50 μm. Next, the modulus of elasticity of Layer B is measured as the indentation modulus using a nanoindentation method. The indentation modulus is measured using a microhardness tester (e.g., product name "DUH-W201" manufactured by Shimadzu Corporation) by applying a load with a Vickers indenter at a loading rate of 0.28 mN / sec, holding a maximum load of 10 mN for 10 seconds, and then unloading at a loading rate of 0.28 mN / sec. Measurements are made at 160°C at 20 random positions on the cross-sectional sample, and the average value is taken as the modulus of elasticity.

[0146] From the viewpoint of conformability to unevenness, the average thickness of Layer B is preferably 5 μm to 50 μm, more preferably 10 μm to 40 μm, and even more preferably 15 μm to 30 μm.

[0147] <<Layer A>> The laminate according to the present disclosure has a layer A on which the layer B is provided.

[0148] From the viewpoint of making the dielectric loss tangent of the laminate 0.01 or less, Layer A preferably contains a polymer having a dielectric loss tangent of 0.01 or less.

[0149] Layer A may contain only one type of polymer having a dielectric loss tangent of 0.01 or less, or may contain two or more types of polymers.

[0150] The dielectric loss tangent of a polymer having a dielectric loss tangent of 0.01 or less is preferably 0.005 or less, more preferably more than 0 and 0.003 or less, from the viewpoint of the dielectric loss tangent of a polymer film.

[0151] Examples of polymers having a dielectric dissipation factor of 0.01 or less 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 phenolic resins, epoxy resins, polyimides, and cyanate resins.

[0152] From the viewpoint of the dielectric loss tangent of the polymer film, the polymer having a dielectric loss tangent of 0.01 or less is preferably a liquid crystal polymer. That is, Layer A preferably contains a liquid crystal polymer. Preferred embodiments of the liquid crystal polymer are the same as the preferred embodiments of the liquid crystal polymer that may be contained in Layer B.

[0153] Layer A may contain a filler in addition to the polymer having a dielectric loss tangent of 0.01 or less. When Layer A contains a filler, the rigidity is improved and wiring distortion and the like can be suppressed.

[0154] The filler may be particulate or fibrous, and may be inorganic or organic particles, specific examples of which are as described above.

[0155] Layer A may contain only one type of filler, or may contain two or more types of filler. When Layer A contains a filler, the content of the filler is preferably 30% by mass to 95% by mass, more preferably 50% by mass to 90% by mass, and particularly preferably 60% by mass to 80% by mass, relative to the total mass of Layer A, from the viewpoints of the dielectric loss tangent, heat resistance, and step-following ability of the laminate.

[0156] Layer A may contain other additives in addition to the above-mentioned components. Preferred embodiments of the other additives that may be contained in Layer A are the same as preferred embodiments of the other additives that may be contained in Layer B.

[0157] Layer A may also contain, as other additives, a resin other than a polymer having a dielectric dissipation factor of 0.01 or less. Examples of the resin other than a polymer having a dielectric dissipation factor of 0.01 or less include thermoplastic resins other than liquid crystal polyester, such as polypropylene, polyamide, polyester other than liquid crystal polyester, polyphenylene sulfide, polyether ketone, polycarbonate, polyether sulfone, polyphenylene ether and modified products thereof, and polyetherimide; elastomers such as copolymers of glycidyl methacrylate and polyethylene; and thermosetting resins such as phenolic resins, epoxy resins, polyimide resins, and cyanate resins.

[0158] The total content of other additives in Layer A is preferably 25 parts by mass or less, more preferably 10 parts by mass or less, and even more preferably 5 parts by mass or less, per 100 parts by mass of the content of the polymer having a dielectric tangent of 0.01 or less.

[0159] The elastic modulus of Layer A at 160° C. is preferably greater than 0.60 MPa, and more preferably equal to or greater than 10 MPa. When the elastic modulus of Layer A at 160° C. is greater than 0.60 MPa, Layer A can support Layer B and has excellent step conformability. The upper limit of the elastic modulus of Layer A at 160° C. is not particularly limited, but is 1000 MPa from the viewpoint of suppressing wiring distortion, etc.

[0160] In the present disclosure, the modulus of elasticity of Layer A at 160°C is measured by the following method. A film cross-section sample is prepared by obliquely cutting with a microtome so that the cross-section thickness is 50 μm. Next, the modulus of elasticity of Layer A is measured as the indentation modulus using a nanoindentation method. The indentation modulus is measured using a microhardness tester (e.g., product name "DUH-W201" manufactured by Shimadzu Corporation) by applying a load with a Vickers indenter at a loading rate of 0.28 mN / sec, holding a maximum load of 10 mN for 10 seconds, and then unloading at a loading rate of 0.28 mN / sec. Measurements are made at 160°C at 20 random positions on the cross-section sample, and the average value is taken as the modulus of elasticity.

[0161] The average thickness of Layer A is not particularly limited, but from the viewpoints of the dielectric loss tangent, heat resistance, and suppression of wiring distortion of the laminate, it is preferably 5 μm to 90 μm, more preferably 10 μm to 70 μm, and particularly preferably 15 μm to 50 μm.

[0162] From the viewpoint of adhesion to a metal substrate, the laminate according to the present disclosure preferably further includes a layer C in addition to the layer A and the layer B, and more preferably includes the layer B, the layer A, and the layer C in this order.

[0163] <<Layer C>> Layer C is preferably an adhesive layer, that is, Layer C is preferably a surface layer (outermost layer).

[0164] From the viewpoint of dielectric loss tangent, it is preferable that Layer C contains at least one polymer.

[0165] The preferred embodiments of the polymer used in Layer C are the same as the preferred embodiments of the polymer used in Layer A having a dielectric loss tangent of 0.01 or less.

[0166] The polymer contained in Layer C may be the same as or different from the polymer contained in Layer A or Layer B. However, from the viewpoint of adhesion between Layer A and Layer C, it is preferable that the polymer be the same as the polymer contained in Layer A.

[0167] Furthermore, the layer C preferably contains an epoxy resin to bond the metal layer and the layer A together.

[0168] The epoxy resin is preferably a crosslinked product of a polyfunctional epoxy compound. A polyfunctional epoxy compound is a compound having two or more epoxy groups. The number of epoxy groups in the polyfunctional epoxy compound is preferably 2 to 4.

[0169] In particular, from the viewpoints of the dielectric loss tangent of the laminate and the adhesiveness to the metal layer, it is preferable that Layer C contains an aromatic polyester amide and an epoxy resin.

[0170] Layer C may contain a filler. Preferred embodiments of the filler used in Layer C are the same as preferred embodiments of the filler used in Layer A.

[0171] Layer C may contain additives other than those described above. Preferred embodiments of the additives used in Layer C are the same as the preferred embodiments of the additives used in Layer A, except as described below.

[0172] 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 laminate and adhesion to metal.

[0173] Average thickness T of layer A Ａ 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 laminate and the adhesion to the metal layer, the value of is preferably greater than 1, more preferably 2 to 100, even more preferably 2.5 to 20, and particularly preferably 3 to 10. Ｂ and the average thickness T of layer C Ｃ T, which is the ratio of Ｂ / T Ｃ From the viewpoints of the dielectric loss tangent of the laminate 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.

[0174] Furthermore, from the viewpoints of the dielectric loss tangent of the laminate and the adhesion to the metal layer, the average thickness of Layer C is preferably 0.1 μm to 20 μm, more preferably 0.5 μm to 15 μm, even more preferably 1 μm to 10 μm, and particularly preferably 2 μm to 8 μm.

[0175] The average thickness of each layer in the laminate was measured as follows.

[0176] The laminate is cut in a plane perpendicular to the plane direction of the laminate, and the thickness is measured at five or more points on the cross section, and the average value of the measurements is taken as the average thickness.

[0177] The laminate according to the present disclosure preferably has a dielectric loss tangent of 0.01 or less, more preferably 0.005 or less, and even more preferably 0.003 or less. The lower limit of the dielectric loss tangent is not particularly limited, but is, for example, 0.0005.

[0178] The average thickness of the laminate is not particularly limited, but from the viewpoint of the dielectric loss tangent and step-following ability, it is preferably 5 μm to 90 μm, more preferably 10 μm to 70 μm, and particularly preferably 15 μm to 50 μm.

[0179] The average thickness of the laminate 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.

[0180] <Method for Producing Laminate> (Film Formation) The method for producing the laminate according to the present disclosure is not particularly limited, and known methods can be used.

[0181] Suitable film-forming methods include, for example, co-casting, multi-layer coating, co-extrusion, etc. Among these, the co-casting method is preferred.

[0182] When a multilayer structure is produced by a co-casting method or a multi-layer coating method, it is preferable to carry out the co-casting method or the multi-layer coating method using a layer A-forming composition, a layer B-forming composition, a layer C-forming composition, etc., in which the components of each layer are dissolved or dispersed in a solvent.

[0183] Examples of the solvent include the solvent contained in the dispersion liquid.

[0184] In addition, in the method for producing a laminate according to the present disclosure, when the laminate is produced by the above-mentioned co-casting method, multi-layer coating method, co-extrusion method, or the like, a support may be used.

[0185] Examples of the support include a metal drum, a metal band, a glass plate, a resin film, and a metal foil, and among these, the support is preferably a metal drum, a metal band, or a resin film.

[0186] The support may have a surface treatment layer formed on its surface to facilitate peeling. The surface treatment layer may be made of hard chrome plating, fluororesin, or the like. The average thickness of the support is not particularly limited, but is preferably 25 μm to 75 μm, and more preferably 50 μm to 75 μm.

[0187] The method for removing at least a part of the solvent from the cast or coated film-like composition (coating film) is not particularly limited, and any known drying method can be used.

[0188] (Stretching) The method for producing a laminate according to the present disclosure can be appropriately combined with stretching in order to control molecular orientation and adjust the thermal expansion coefficient and mechanical properties. The stretching method is not particularly limited, and known methods can be used. The stretching may be performed in a solvent-containing state or in a dry film state. Stretching in a solvent-containing state may be performed by gripping the laminate and stretching it, or by utilizing autogenous shrinkage due to drying without stretching it. Stretching is particularly effective for improving breaking elongation and breaking strength when the film brittleness has decreased due to the addition of an inorganic filler or the like.

[0189] The laminate according to the present disclosure can be used for various purposes, and in particular, can be suitably used as a film for electronic components such as printed wiring boards, and can be more suitably used as a flexible printed circuit board. The laminate according to the present disclosure can also be suitably used as a liquid crystal polymer film for metal bonding.

[0190] [Wiring Board] A wiring board according to the present disclosure comprises a substrate, wiring patterns arranged on at least one surface of the substrate, a layer B arranged between the wiring patterns and on the wiring patterns, and a layer A arranged on the layer B, wherein the layer B has a phase-separated structure including at least two phases, the layer B having an elastic modulus at 160°C of 0.60 MPa or less, a first phase which is one of the at least two phases having an elastic modulus G1 at 260°C of more than 0.10 MPa, and a second phase different from the first phase having an elastic modulus G2 at 260°C of 0.10 MPa or less, and the number of regions having a maximum length of 10 μm or less in the continuous structure of the first phase is 0.02 / μm in a cross section along the thickness direction of the layer B. ２ That's all.

[0191] In the wiring board according to the present disclosure, in a cross section along the thickness direction of the layer B, the number of regions in the continuous structure of the first phase having a maximum length of 10 μm or less is 0.02 / μm ２ For these reasons, the film has excellent step-following ability and heat resistance.

[0192] <Substrate> The material of the substrate is not particularly limited, but preferably contains a resin, more preferably contains a liquid crystal polymer, and is more preferably a liquid crystal polymer film.

[0193] The average thickness of the substrate is not particularly limited, but is preferably 5 μm to 100 μm, more preferably 10 μm to 80 μm, and even more preferably 20 μm to 70 μm.

[0194] <Wiring Pattern> The wiring board according to the present disclosure has a wiring pattern on at least one surface of the substrate. Layer B is disposed between and on the wiring patterns, and thus the wiring pattern is embedded in the wiring board according to the present disclosure. The wiring pattern can be embedded in the wiring board, for example, by the following method. First, a metal layer is formed on the substrate, and the metal layer is etched in a pattern. This results in a substrate with a wiring pattern. Next, the substrate with a wiring pattern and another substrate having layers A and B are overlapped so that the wiring pattern in the substrate with a wiring pattern contacts layer B. After overlapping the substrate with a wiring pattern and the other substrate, they may be bonded together or heat-sealed. This results in a wiring board with an embedded wiring pattern.

[0195] The material of the wiring pattern is not particularly limited, but is preferably a metal, more preferably silver or copper.

[0196] The thickness of the wiring pattern is not particularly limited, but is preferably 5 μm to 40 μm, and more preferably 5 μm to 35 μm.

[0197] The thickness of the wiring pattern is measured by cutting the wiring substrate with a microtome and observing the cut surface with an optical microscope.

[0198] Preferred aspects of Layer A and Layer B included in the wiring board according to the present disclosure are the same as the preferred aspects of Layer A and Layer B included in the laminate according to the present disclosure.

[0199] From the viewpoint of heat resistance, the wiring board according to the present disclosure preferably further includes a layer C in addition to the above-described layer A and layer B, and layer C is preferably disposed on layer A. Preferred aspects of layer C are the same as preferred aspects of layer C that may be included in the laminate according to the present disclosure.

[0200] <Method for Manufacturing Wiring Board> (First Aspect) A first aspect of the method for manufacturing a wiring board according to the present disclosure preferably includes the steps of: overlaying a laminate according to the present disclosure on a wiring pattern of a substrate having a wiring pattern; and heating the substrate having a wiring pattern and the laminate according to the present disclosure in an overlaid state to obtain a wiring board. The substrate having a wiring pattern and the laminate are overlaid so that the wiring pattern of the substrate having a wiring pattern contacts Layer B of the laminate.

[0201] -Laminating Step- In a first aspect of the method for producing a wiring board according to the present disclosure, the laminate according to the present disclosure is laminated on the wiring pattern of a substrate having a wiring pattern.

[0202] When stacking the laminates, the laminate may simply be placed on the wiring pattern, or the laminate may be pressed onto the wiring pattern by applying pressure.

[0203] The substrate having a wiring pattern may have a wiring pattern formed on only one surface of the substrate, or may have a wiring pattern formed on both surfaces of the substrate.

[0204] The substrate with a wiring pattern can be produced using a known method. For example, a metal layer is attached to at least one surface of the substrate to obtain a wiring board comprising the substrate and the metal layer disposed on at least one surface of the substrate. The metal layer is then subjected to a known patterning process to obtain the substrate with a wiring pattern.

[0205] The preferred embodiments of the substrate and the wiring pattern in the substrate having a wiring pattern are the same as those of the substrate and the wiring pattern explained in the section on the wiring board above.

[0206] -Heating Step- In the first aspect of the method for producing a wiring board according to the present disclosure, after the above-mentioned superposing step, the substrate having a wiring pattern and the laminate according to the present disclosure are heated in a superposed state to obtain a wiring board.

[0207] The heating method is not particularly limited, and can be performed using, for example, a heat press.

[0208] The heating temperature is preferably 50°C to 300°C, and more preferably 100°C to 250°C.

[0209] It is preferable to apply pressure when heating, and the pressure is preferably 0.5 MPa to 30 MPa, and more preferably 1 MPa to 20 MPa.

[0210] The heating time is not particularly limited and is, for example, 1 minute to 2 hours.

[0211] (Second Aspect) A second aspect of the method for producing a wiring board according to the present disclosure preferably includes the steps of applying a layer A-forming solution onto a support to form layer A, superimposing a film according to the present disclosure and a substrate with a wiring pattern on layer A in this order, and heating the support on which layer A has been formed, the polymer film according to the present disclosure, and the substrate with a wiring pattern in a superimposed state to obtain a wiring board. The polymer film and the substrate with a wiring pattern are superimposed so that the wiring pattern of the substrate with a wiring pattern comes into contact with the polymer film.

[0212] Examples of the support include the same supports as those used in the above-mentioned method for producing a laminate.

[0213] The details of the substrate having a wiring pattern are the same as those of the first embodiment.

[0214] The details of the heating step are the same as those in the first embodiment.

[0215] The wiring board according to the present disclosure can be used for various applications, and among others, the wiring board according to the present disclosure can be suitably used as a flexible printed circuit board.

[0216] 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.

[0217] Details of the materials used in the preparation of the film and laminate are as follows.

[0218] P1: Aromatic polyesteramide prepared according to the following production method

[0219] -Synthesis of aromatic polyesteramide P1- A reactor equipped with a stirrer, torque meter, nitrogen gas inlet tube, thermometer, and reflux condenser was charged with 940.9 g (5.0 mol) of 6-hydroxy-2-naphthoic acid, 415.3 g (2.5 mol) of isophthalic acid, 377.9 g (2.5 mol) of acetaminophen, and 867.8 g (8.4 mol) of acetic anhydride. The gas inside the reactor was replaced with nitrogen gas, and then the mixture was heated from room temperature (23°C, the same applies hereinafter) to 140°C over 60 minutes while stirring under a nitrogen gas stream, and refluxed at 140°C for 3 hours. Next, while distilling off by-product acetic acid and unreacted acetic anhydride, the mixture was heated from 150°C to 300°C over 5 hours and held at 300°C for 30 minutes. The contents were then removed from the reactor and cooled to room temperature. The resulting solid was pulverized in a grinder to obtain powdered aromatic polyesteramide P1a. The flow initiation temperature of the aromatic polyesteramide P1a was 193°C. The aromatic polyesteramide P1a was a wholly aromatic polyesteramide. The aromatic polyesteramide P1a was heated from room temperature to 160°C over 2 hours and 20 minutes under a nitrogen atmosphere, then heated from 160°C to 180°C over 3 hours and 20 minutes, and held at 180°C for 5 hours to undergo solid-state polymerization, followed by cooling. The mixture was then pulverized in a grinder to obtain a powdered aromatic polyesteramide P1b. The flow initiation temperature of the aromatic polyesteramide P1b was 220°C. The aromatic polyesteramide P1b was heated from room temperature to 180°C over 1 hour and 25 minutes under a nitrogen atmosphere, then heated from 180°C to 255°C over 6 hours and 40 minutes, and held at 255°C for 5 hours to undergo solid-state polymerization, followed by cooling to obtain a powdered aromatic polyesteramide P1. The flow initiation temperature of the aromatic polyesteramide P1 was 302°C. The melting point of the aromatic polyesteramide P1 was measured using a differential scanning calorimeter and found to be 311° C. The solubility of the aromatic polyesteramide P1 in N-methylpyrrolidone at 140° C. was 1% by mass or more.

[0220] P2: Polyphenylene sulfide (product name "Torelina", manufactured by Toray Industries, Inc.)

[0221] B1: Particles of hydrogenated styrene-isobutylene-styrene block copolymer (product name "SIBSTAR103T-UL", manufactured by Kaneka Corporation) (average particle size: 10 μm, weight average molecular weight 100,000) B2: Particles of polycarbonate (product name "Iupizeta FPC-2136", manufactured by Mitsubishi Gas Chemical Company, Inc.) (average particle size: 25 μm, weight average molecular weight 100,000) B3: Particles of hydrogenated styrene-isobutylene-styrene block copolymer prepared according to the following production method. A reaction vessel was charged with 452 mL of 1-chlorobutane, 319 mL of hexane, and 0.55 g of 1,4-bis(1-chloro-1-methylethyl)benzene and cooled to -75°C. After that, 5 mg of dimethylacetamide, 2.3 mL of isobutylene, and 0.08 mL of titanium tetrachloride were added and stirred for 1.5 hours. Next, 0.6 g of styrene was added to the reaction solution, and stirring was continued for an additional 60 minutes. After that, the contents of the reactor were poured into water and the organic layer and aqueous layer were separated. After washing with water, the organic layer was poured into a large amount of methanol to precipitate the polymer, and the resulting polymer was vacuum dried at 60°C for 24 hours. The resultant was pulverized in a pulverizer to obtain powdery hydrogenated styrene-isobutylene-styrene block copolymer B5. The hydrogenated styrene-isobutylene-styrene block copolymer B5 had a weight average molecular weight of 900 and an average particle size of 25 μm.

[0222] B4: Polytetrafluoroethylene particles prepared according to the following production method. 70 L of deionized water was added to a stainless steel polymerization tank equipped with a stirring blade, and after removing the air from the tank, 100 g of ethane and tetrafluoroethylene (TFE) were added and the temperature was raised to 85°C. TFE was then added again, and the pressure in the tank was adjusted to 0.8 MPa. 250 ppm / H ２ O ammonium persulfate and 250 ppm / H ２Disuccinic acid peroxide (O) was added in the form of an aqueous solution. Polymerization was carried out while maintaining the pressure and temperature in the tank at 0.85 MPa and 85°C, respectively. When the TFE supply amount reached 12 kg, the polymerization reaction was terminated and the pressure in the tank was released to normal pressure. After cooling the tank to room temperature (25°C), the obtained particles were washed with deionized water. The particles were filtered and dried for 12 hours in a hot air circulation dryer at 170°C to obtain polytetrafluoroethylene (PTFE) particles B4. The weight-average molecular weight of the obtained PTFE particles was 5,000 and the average particle size was 10 μm.

[0223] Dispersions 1 to 7, X1 to X3 Particles of polymer A and polymer B shown in Table 1 were mixed in the amounts (% by mass) shown in Table 1, and N-methylpyrrolidone was added to adjust the solids concentration to 20% by mass. The mixed liquid was subjected to bead mill treatment using 1 mm diameter zirconia beads in a bead mill disperser (product name "Labostar Mini MGF015", manufactured by Ashizawa Finetech Co., Ltd.) for the time shown in Table 1 to obtain dispersions.

[0224] Examples 1 to 7, Comparative Examples 1 to 4 Films or laminates were produced by the following methods.

[0225] To prepare a film or a laminate, a solution for forming Layer A and a solution for forming Layer B were prepared.

[0226] - Preparation of Layer A Forming Solution - N-methylpyrrolidone was added to the materials listed in Table 1 to adjust the solid content concentration to 8 mass % to obtain a layer A forming solution.

[0227] -Preparation of Layer B Forming Solution- The above dispersions 1 to 7 and X1 to X3 were used as layer B forming solutions.

[0228] [Preparation of Single-Sided Copper-Clad Laminates] - Examples 1 and 2, Examples 5-7, Comparative Examples 1-4 - The Layer B-forming solution was delivered to a slot die coater equipped with a slide coater and applied to the treated surface of copper foil (product name "CF-T9DA-SV-18", manufactured by Fukuda Metal Foil & Powder Co., Ltd.) with the flow rate adjusted to a film thickness of 30 μm. The coating was dried at 40°C for 4 hours to remove the solvent from the coating. The temperature was then increased from room temperature (25°C) to 300°C at a rate of 1°C / min under a nitrogen atmosphere. Heat treatment was performed at 300°C for 2 hours to obtain a laminate B in which Layer B (film B) was formed on the support. In the obtained laminate B, film B had a phase-separated structure. Similarly, a laminate A in which Layer A (film A) was formed on the support was obtained using the Layer A-forming solution. The laminate A and laminate B were overlapped so that film A of the obtained laminate A and film B of laminate B were in contact with each other, and a lamination process was carried out for 1 minute using a laminator (product name "Vacuum Laminator V-130", manufactured by Nikko Materials Co., Ltd.) at 140°C and a lamination pressure of 0.4 MPa, to obtain a laminate in which the support, layer A, layer B, and support were laminated in this order. The support on the layer B side was peeled off, and a laminate (single-sided copper-clad laminate) in which the support, layer A, and layer B were laminated in this order was obtained.

[0229] Examples 3 and 4 The obtained Layer A-forming solution and Layer B-forming solution were fed to a slot die coater equipped with a slide coater and applied to the treated surface of copper foil (product name "CF-T9DA-SV-18", manufactured by Fukuda Metal Foil & Powder Co., Ltd.) by adjusting the flow rate so that Layer A had a film thickness of 20 μm and Layer B had a film thickness of 30 μm. The coating was dried at 40°C for 4 hours to remove the solvent from the coating. The temperature was then increased from room temperature (25°C) to 300°C at a rate of 1°C / min under a nitrogen atmosphere. A heat treatment was performed by holding at 300°C for 2 hours to obtain a laminate (single-sided copper-clad laminate) in which the support, Layer A, and Layer B were laminated in this order. In the obtained laminate, Layer B had a phase-separated structure.

[0230] [Preparation of 4-Layer Copper-Clad Laminate] The prepared single-sided copper-clad laminate was laminated so that Layer B and the support (copper foil) were in contact. Furthermore, the Layer B side of the outermost single-sided copper-clad laminate was laminated with copper foil (product name "CF-T9DA-SV-18", manufactured by Fukuda Metal Foil and Powder Co., Ltd.). This resulted in a laminate laminated in the following order: "copper foil, Layer A, Layer B" / "copper foil, Layer A, Layer B" / "copper foil, Layer A, Layer B" / "copper foil, Layer A, Layer B" / "copper foil, Layer A, Layer B" / copper foil. A lamination process was performed for 1 minute using a laminator (product name "Vacuum Laminator V-130", manufactured by Nikko Materials Co., Ltd.) at 140°C and a lamination pressure of 0.4 MPa, to obtain a precursor of a 4-layer copper-clad laminate. Subsequently, the obtained precursor of the four-layer copper-clad laminate was subjected to thermocompression bonding at 230°C and 4 MPa for 60 minutes using a thermocompression bonding machine (product name "MP-SNL", manufactured by Toyo Seiki Seisakusho Co., Ltd.), to produce a four-layer copper-clad laminate.

[0231] [Preparation of wiring board] -Preparation of substrate with wiring pattern- Copper foil (product name "CF-T9DA-SV-18", average thickness 18 μm, manufactured by Fukuda Metal Foil & Powder Co., Ltd.) and a liquid crystal polymer film (product name "CTQ-50", average thickness 50 μm, manufactured by Kuraray Co., Ltd.) were prepared as a substrate. The copper foil, substrate, and copper foil were stacked in this order so that the treated surface of the copper foil was in contact with the substrate. Using a laminator (product name "Vacuum Laminator V-130", manufactured by Nikko Materials Co., Ltd.), a lamination process was performed for 1 minute under conditions of 140°C and a lamination pressure of 0.4 MPa, to obtain a precursor of a double-sided copper-clad laminate. Next, using a thermocompression bonding machine (product name "MP-SNL", manufactured by Toyo Seiki Seisakusho, Ltd.), the obtained precursor of the double-sided copper-clad laminate was thermocompressed for 10 minutes under conditions of 300 ° C and 4.5 MPa to produce a double-sided copper-clad laminate. The surfaces of the copper foil on both sides of the double-sided copper-clad laminate were roughened, and a dry film resist was attached. After exposure and development so that the wiring pattern remained, etching was performed, and the dry film was then removed to produce a substrate with a wiring pattern having a line / space of 100 μm / 100 μm including a ground line and three pairs of signal lines on both sides of the substrate. The length of the signal line was 50 mm, and the width was set so that the characteristic impedance was 50 Ω.

[0232] - Preparation of wiring board - The above-mentioned substrate with wiring pattern was superimposed on the layer B side of the prepared single-sided copper-clad laminate, and a wiring board was obtained by hot pressing for 1 hour under conditions of 160°C and 4 MPa. The obtained wiring board had a wiring pattern (ground line and signal line) embedded therein, and the thickness of the wiring pattern was 18 μm.

[0233] The following measurements and evaluations were carried out, and the results are shown in Table 1.

[0234] <<Measurement Method>> [Elastic Modulus of Layer B at 160°C] A cross section of a single-sided copper-clad laminate was exposed using a cryomicrotome. Next, Layer B was identified, and the elastic modulus of Layer B at 160°C was measured as the indentation elastic modulus using a nanoindentation method. The indentation elastic modulus was measured using a microhardness tester (product name "DUH-W201", manufactured by Shimadzu Corporation) by applying a load with a Vickers indenter at a loading rate of 0.28 mN / s, holding a maximum load of 10 mN for 10 seconds, and then unloading at a loading rate of 0.28 mN / s.

[0235] [Elastic Modulus of Polymer A and Polymer B at 260°C] The elastic modulus of Polymer A and Polymer B at 260°C was measured as the indentation modulus using a nanoindentation method. The indentation modulus was measured using a microhardness tester (product name "DUH-W201", manufactured by Shimadzu Corporation) by applying a load with a Vickers indenter at a loading rate of 0.28 mN / sec, holding a maximum load of 10 mN for 10 seconds, and then unloading at a loading rate of 0.28 mN / sec.

[0236] [Elastic modulus of the first and second phases in Layer B at 260°C] A cross section of a single-sided copper-clad laminate was exposed using a cryomicrotome. Next, the first and second phases in Layer B were identified, and the elastic moduli of the first and second phases at 260°C were measured as indentation modulus using a nanoindentation method. The indentation modulus was measured using a microhardness tester (product name "DUH-W201", manufactured by Shimadzu Corporation) by applying a load with a Vickers indenter at a loading rate of 0.28 mN / s, holding a maximum load of 10 mN for 10 seconds, and then unloading at a loading rate of 0.28 mN / s.

[0237] [Number of specific regions] The single-sided copper-clad laminate was cut in the thickness direction using a cryomicrotome to expose a cross section. The cross section was observed using an optical microscope. The continuous structure of the first phase was identified from the cross-sectional image. Specifically, an amorphous shape in the first phase, in which spherical or elliptical shapes are bonded to each other, was determined to be the continuous structure of the first phase. If it was spherical or elliptical, it was not determined to be the continuous structure of the first phase. In any 30 μm × 30 μm region of the cross-sectional image, the maximum length of the continuous structure of the first phase was measured. The number of regions with a maximum length of 10 μm or less was counted. The average number in three regions was calculated. The obtained average value was divided by 900 to obtain a value of 1 μm. ２ It was converted into the number of pieces per

[0238] [Viscosity of Dispersion] The viscosity was measured using a rheometer (product name "HAAKE MARS40 / 60", manufactured by ThermoFisher Scientific) at 25° C. The viscosity was measured while scanning the frequency from 1000 / s to 0.1 / s.

[0239] [Dielectric loss tangent] The copper foil of a single-sided copper-clad laminate was removed with an aqueous solution of ferric chloride, washed with pure water, and then dried to obtain a polymer film. The dielectric loss tangent was measured using a resonance perturbation method at a frequency of 10 GHz. A 10 GHz cavity resonator (Kanto Electronics Application Development Co., Ltd., CP531) was connected to a network analyzer (Agilent Technology, Inc., E8363B). The polymer film was inserted into the cavity resonator, and the dielectric loss tangent of the film or laminate was measured from the change in resonance frequency before and after insertion for 96 hours under an environment of 25°C and 60% RH.

[0240] <<Evaluation Method>> [Step Conformability] The wiring board was cut in the thickness direction with a microtome, and the cross section was observed with an optical microscope. The length L1 of the gap occurring in the in-plane direction between layer B and the wiring pattern was measured. The average value for 10 locations was calculated. The evaluation criteria were as follows: A: No gap was observed. B: The average value of L1 was less than 1 μm. C: The average value of L1 was 1 μm or more and less than 2 μm. D: The average value of L1 was 2 μm or more.

[0241] [Heat Resistance] The four-layer copper-clad laminate was cut into 30 mm x 30 mm pieces to prepare evaluation samples. The evaluation samples were treated for 168 hours in a thermo-hygrostat chamber at a temperature of 85°C and a relative humidity of 85%. The evaluation samples were then placed in an oven set to 260°C and heated for 15 minutes. After heating, the evaluation samples were cut with a razor, and the cross sections were observed under an optical microscope to evaluate the state of peeling. A: No distortion of the laminate was observed. Furthermore, no peeling was observed between Layer B and the copper foil. B: Distortion of the laminate occurred, but no peeling was observed between Layer B and the copper foil. C: Peeling was observed between Layer B and the copper foil with a width of 1.0 mm or less. D: Peeling was observed between Layer B and the copper foil with a width of more than 1.0 mm.

[0242]

[0243]

[0244] As shown in Table 2, Examples 1 to 9 are films or laminates produced using dispersions containing particles including polymer A having an elastic modulus at 260°C of more than 0.10 MPa and polymer B having an elastic modulus at 260°C of 0.10 MPa or less, and a solvent, and having a viscosity η2 at a shear rate of 100 / s at 25°C of 800 mPa s or more, and a ratio η1 / η2 of the viscosity η1 at a shear rate of 0.1 / s at 25°C to the viscosity η2 at a shear rate of 100 / s at 25°C of 10 or more, and therefore were found to have excellent step-following ability and heat resistance.

[0245] On the other hand, in Comparative Example 1, a dispersion having a viscosity η2 of less than 800 mPa s was used, and therefore it was found to have poor heat resistance. In Comparative Example 2, a dispersion having a viscosity η1 / η2 of less than 10 was used, and therefore it was found to have poor heat resistance. In Comparative Example 3, a dispersion having a viscosity η2 of less than 800 mPa s and a viscosity η1 / η2 of less than 10 was used, and therefore it was found to have poor step-following ability and heat resistance. In Comparative Example 4, the elastic moduli of the first phase and the second phase at 260°C were both 0.10 MPa or less, and therefore it was found to have poor heat resistance.

[0246] In Example 1, Polymer B contained a polymer having a weight average molecular weight of 1,000 or more, and it was found that Example 1 had superior heat resistance compared to Example 6.

[0247] In Example 1, Polymer B contained a thermoplastic elastomer, and it was found that compared with Example 5, Example 1 was superior in step conformability and heat resistance.

[0248] In Example 1, Polymer B contained an elastomer containing structural units derived from styrene, and it was found that compared with Example 7, Example 1 was superior in conformability to unevenness and heat resistance.

[0249] In Example 1, the ratio of the content of particles containing polymer B to the content of polymer A was 1 or more, and it was found that Example 1 had superior step-following ability compared to Example 9.

[0250] The disclosure of Japanese Patent Application No. 2023-140489, filed on August 30, 2023, 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 dispersion comprising particles including a polymer A having an elastic modulus of more than 0.10 MPa at 260°C and a polymer B having an elastic modulus of 0.10 MPa or less at 260°C, and a solvent, wherein the viscosity η2 at a shear rate of 100 / s at 25°C is 800 mPa·s or more, and the ratio η1 / η2 of the viscosity η1 at a shear rate of 0.1 / s at 25°C to the viscosity η2 at a shear rate of 100 / s at 25°C is 10 or more.

2. The dispersion according to claim 1, wherein the polymer B has a weight average molecular weight of 1,000 or more.

3. The dispersion according to claim 1 or 2, wherein the polymer B is a thermoplastic elastomer.

4. The dispersion according to claim 3, wherein the thermoplastic elastomer is an elastomer containing structural units derived from styrene.

5. The dispersion according to claim 3, wherein the thermoplastic elastomer is at least one selected from the group consisting of styrene-ethylene-butylene-styrene block copolymers, styrene-isobutylene-styrene block copolymers, styrene-ethylene-propylene-styrene copolymers, styrene-isoprene-styrene block copolymers, and hydrogenated products thereof.

6. The dispersion according to claim 1 or 2, wherein the ratio of the content of the particles containing said polymer B to the content of said polymer A is 1 or more.

7. A film which is a dried product of the dispersion according to claim 1 or 2.

8. A film having a phase separation structure including at least two phases, wherein the elastic modulus at 160°C is 0.60 MPa or less, the elastic modulus G1 at 260°C of a first phase which is one of the at least two phases is more than 0.10 MPa, and the elastic modulus G2 at 260°C of a second phase different from the first phase is 0.10 MPa or less, and in a cross section along the thickness direction of the film, the number of regions in the continuous structure of the first phase having a maximum length of 10 μm or less is 0.02 / μm. ２ That's it, film.

9. The film of claim 8, wherein said second phase comprises a polymer having a weight average molecular weight of 1000 or greater.

10. The film according to claim 9, wherein the polymer having a weight average molecular weight of 1000 or more is a thermoplastic elastomer.

11. The film according to claim 10, wherein the thermoplastic elastomer is an elastomer containing structural units derived from styrene.

12. The film according to claim 10, wherein the thermoplastic elastomer is at least one selected from the group consisting of styrene-ethylene-butylene-styrene block copolymers, styrene-isobutylene-styrene block copolymers, styrene-ethylene-propylene-styrene copolymers, styrene-isoprene-styrene block copolymers, and hydrogenated products thereof.

13. The film according to any one of claims 8 to 12, wherein the proportion of the second phase in a cross section along the thickness direction of the film is 50 area % or more.

14. A polymeric material comprising a layer A and a layer B disposed on at least one surface of the layer A, the layer B having a phase-separated structure including at least two phases, the layer B having an elastic modulus of 0.60 MPa or less at 160°C, a first phase which is one of the at least two phases having an elastic modulus G1 at 260°C of more than 0.10 MPa, and a second phase different from the first phase having an elastic modulus G2 at 260°C of 0.10 MPa or less, and in a cross section along the thickness direction of the layer B, the number of regions in the continuous structure of the first phase having a maximum length of 10 μm or less is 0.02 / μm ２ This is the laminate.

15. The laminate of claim 14, wherein Layer A comprises a liquid crystal polymer.

16. A laminate comprising a substrate, a wiring pattern disposed on at least one surface of the substrate, a layer B disposed between the wiring patterns and on the wiring pattern, and a layer A disposed on the layer B, wherein the layer B has a phase separation structure including at least two phases, the layer B has an elastic modulus of 0.60 MPa or less at 160°C, a first phase which is one of the at least two phases has an elastic modulus G1 at 260°C of more than 0.10 MPa, and a second phase different from the first phase has an elastic modulus G2 at 260°C of 0.10 MPa or less, and in a cross section along the thickness direction of the layer B, the number of regions in the continuous structure of the first phase having a maximum length of 10 μm or less is 0.02 / μm. ２ That's it for the wiring board.

17. A method for producing a dispersion liquid, comprising: mixing particles containing polymer A having an elastic modulus of more than 0.10 MPa at 260°C and polymer B having an elastic modulus of 0.10 MPa or less at 260°C with a solvent; and subjecting the mixture to a bead mill treatment for 5 to 60 minutes.

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