Film, layered film, layered board, printed circuit board, antenna substrate, antenna module, metamaterial, and electromagnetic-wave-absorbing film

Abstract

This film contains a filler and a resin. The filler is at least one selected from the group consisting of an inorganic filler and an organic filler. The ratio (Do / Di) of the filler density (Di) in the in-plane direction to the filler density (Do) in the thickness direction is 0.5 or greater.

Description

Films, laminated films, laminated plates, printed wiring boards, antenna substrates, antenna modules, metamaterials, and electromagnetic wave absorbing films

[0001] The present disclosure relates to a film and a laminate, and also to electronic components such as printed wiring boards, antenna substrates, and high-frequency antennas that use the film or laminate, and to metamaterials that act on high-frequency signals.

[0002] In recent years, communication devices have become faster, and the frequencies used in communication have tended to become very high. At the same time, there has been an increasing demand for miniaturization and high-density packaging of the electronic components used. High-dielectric materials are preferably used as components constituting such electronic components, and compositions and films in which inorganic fillers are mixed with resins are preferably used. Furthermore, such electronic components are sometimes fabricated by laminating multiple components, and depending on the purpose of each layer, high-dielectric materials or, conversely, low-dielectric materials may be preferably used, or a combination of high-dielectric and low-dielectric materials may be preferably used.

[0003] For example, Japanese Patent Application Laid-Open No. 2017-14406 describes a resin composition containing an epoxy resin, a dielectric powder, a nonionic surfactant 70 that suppresses the formation of aggregates of the dielectric powder, and a curing agent. Japanese Patent Application Laid-Open No. 2021-187969 describes a high-dielectric resin composition containing an epoxy resin and an inorganic filler. International Publication No. 2022 / 124396 describes a high-dielectric resin composition containing a curable resin containing an epoxy resin, a curing agent containing an active ester compound, and an inorganic filler.

[0004] In recent years, the level of demand for signal reliability has been increasing, and there is an increasing demand to reduce the dielectric loss tangent of dielectrics used in electronic components to reduce losses and improve signal quality.

[0005] The present inventors have discovered that by focusing on the orientation state of the filler, it is possible to produce a film that exhibits a desired relative dielectric constant and dielectric loss tangent over a wider range. In particular, it has been discovered that by focusing on the orientation state of the inorganic filler, it is possible to produce a film that combines a high or low dielectric constant with a low dielectric loss tangent. It has also been discovered that by controlling the orientation state of the inorganic filler, it is possible to control the dielectric constant and improve the mechanical properties of the film even when the amount of inorganic filler added is small. An object of one embodiment of the present disclosure is to provide a film (preferably a resin film), a laminate film, a laminate plate, a printed wiring board, an antenna board, an electronic component such as a high-frequency antenna module, a metamaterial that acts on high-frequency signals, and an electromagnetic wave-absorbing film that exhibit a desired relative dielectric constant and dielectric loss tangent over a wider range.

[0006] Specific means for solving the problems are as follows. <1> A film comprising a filler and a resin, wherein the filler is at least one type selected from the group consisting of inorganic fillers and organic fillers, and wherein the ratio (Do / Di) of the number of filler particles per unit area in the in-plane direction (Di) to the number of filler particles per unit area in the thickness direction (Do) is 0.5 or more. <2> The film according to <1>, comprising an inorganic filler and a resin. <3> The film according to <2>, wherein the inorganic filler has a relative dielectric constant of 1 to 20,000. <4> The film according to <2>, wherein the inorganic filler has a relative dielectric constant of 6 to 20,000. <5> The film according to any one of <2> to <4>, wherein the inorganic filler comprises at least one selected from the group consisting of barium titanate, strontium titanate, calcium titanate, magnesium titanate, bismuth titanate, zirconium titanate, zinc titanate, titanium dioxide, magnesium oxide, alumina, tantalum pentoxide, and niobium pentoxide. <6> The film according to <1>, comprising an organic filler and a resin. <7> The film according to <1>, wherein the filler has a relative dielectric constant of 1 to 6. <8> The film according to any one of <1> to <7>, wherein the filler has an average particle size of 0.01 μm to 10 μm. <9> The film according to any one of <1> to <8>, wherein the filler content is 1 to 95% by volume relative to the total amount of the film. <10> The film according to any one of <1> to <9>, wherein the resin comprises at least one selected from the group consisting of a thermoplastic resin, a thermoplastic elastomer, a thermosetting resin, or a semi-cured product of a photocurable resin, a cured product of a thermosetting resin, a cured product of a photocurable resin, a semi-cured product of a thermosetting elastomer, a semi-cured product of a photocurable elastomer, a cured product of a thermosetting elastomer, and a cured product of a photocurable elastomer. <11> The film according to <10>, wherein the thermosetting resin or the photocurable resin is an epoxy resin and further comprises an active ester compound as a curing agent. <12> The film according to any one of <1> to <11>, comprising a plurality of layers A containing 50% or more by volume of a filler and a layer B containing a resin, wherein the plurality of layers A and the layer B are arranged in the same plane and the plurality of layers A are arranged so as not to contact each other.<13> The film according to <12>, further comprising a resin layer C, wherein the resin layer C is in contact with the layer A and the layer B. <14> The film according to any one of <1> to <13>, wherein the surface roughness is 5 μm or less. <15> A laminated film obtained by laminating the films according to any one of <1> to <14> so that they are in contact with each other. <16> A laminated plate comprising a metal layer or a metal pattern on at least one surface of the film according to any one of <1> to <14>. <17> A printed wiring board comprising the laminated plate according to <16>. <18> An antenna substrate comprising the laminated plate according to <16>. <19> An antenna module comprising the antenna substrate according to <18>, which transmits and receives radio waves having a frequency of 6 to 24 GHz. <20> An antenna module comprising the antenna substrate according to <18>, which transmits and receives radio waves having a frequency of 0.5 to 5.9 GHz. <21> A metamaterial comprising the film according to any one of <1> to <14>, and a pattern on at least one surface thereof, the pattern being made of at least one material selected from the group consisting of a conductive material and a material that changes from a non-conductor to a conductor. <22> An electromagnetic-wave-absorbing film comprising the metamaterial according to <21>.

[0007] According to one embodiment of the present disclosure, there is provided a film (preferably a resin film), a laminate film, and a laminate plate that exhibit a desired relative dielectric constant and dielectric loss tangent over a wide range. Also provided are electronic components, such as printed wiring boards, antenna substrates, and high-frequency antenna modules, metamaterials that act on high-frequency signals, and electromagnetic wave-absorbing films, that use the resin film or laminate plate.

[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. The average particle size (e.g., D50) of the inorganic filler in the present disclosure is measured using a laser diffraction / scattering particle size distribution analyzer, such as the LA-950V2 manufactured by HORIBA.

[0009] The film of the present disclosure comprises a filler and a resin, the filler being at least one selected from the group consisting of inorganic fillers and organic fillers, and the ratio (Do / Di) of the number of fillers per unit area in the in-plane direction (Di) to the number of fillers per unit area in the thickness direction (Do) is 0.5 or more. When producing a film from a liquid resin composition, Do / Di can be increased, for example, by the following method, and for films produced by conventional methods, it is about 0.4. Methods for increasing Do / Di include, for example, increasing the solids concentration to 20% by mass or more; increasing the viscosity of the liquid to 10 cP or more; controlling the dispersion conditions to control the aggregation state of the inorganic filler and control buoyancy, or controlling the drying and curing conditions using hot air to generate shrinkage force in the in-plane direction and promote orientation of the inorganic filler in the thickness direction; using a shrinkable substrate, shrinking the substrate after the liquid resin composition has become a gel or film, and promoting orientation of the inorganic filler in the thickness direction. According to the film of the present disclosure, the desired relative dielectric constant and dielectric dissipation factor can be obtained over a wide range. In particular, when the filler is an inorganic filler, a high or low dielectric constant and a low dielectric dissipation factor can be simultaneously achieved. In a film having a Do / Di of 0.5 or more, the inorganic filler is moderately oriented in the thickness direction, so the amount of dielectric in the electric field direction increases, and the dielectric constant increases efficiently. On the other hand, since the dielectric dissipation factor changes depending on the amount of inorganic filler added, by promoting the orientation of the inorganic filler in the thickness direction, the relative dielectric constant and dielectric dissipation factor become within a suitable range. In contrast, JP 2017-14406 A, JP 2021-187969 A, and WO 2022 / 124396 A do not mention Do / Di.

[0010] Each component contained in the film of the present disclosure will be described below.

[0011] The film of the present disclosure contains a filler. The filler is at least one type selected from the group consisting of inorganic fillers and organic fillers. The filler may be an inorganic filler, an organic filler, or a mixture of an inorganic filler and an organic filler. The filler preferably has a relative dielectric constant of 1 to 20,000 at 25°C and a measurement frequency of 10 GHz. For applications requiring a high dielectric constant, the relative dielectric constant of the filler is more preferably 6 to 20,000, and even more preferably 20 to 20,000. For applications requiring a low dielectric constant, the relative dielectric constant of the filler is more preferably 1 to 6, and even more preferably 1 to 4.

[0012] From the viewpoint of achieving both the orientation state of the filler and the dielectric properties, the average particle size of the filler is preferably 0.01 μm to 10 μm, more preferably 0.02 μm to 2 μm, and particularly preferably 0.03 μm to 5 μm. It is also possible to use a mixture of two or more fillers with different average particle sizes or to use spherical fillers. The use of such fillers also has the desirable effect of improving the mechanical properties of the film. From the viewpoint of achieving both the dielectric properties and the mechanical properties, the filler content is preferably 1% by volume to 95% by volume, more preferably 10% by volume to 60% by mass, based on the total amount of the film. When using a mixture of two or more fillers with different average particle sizes or when using spherical fillers, the filler content is preferably 10% by volume to 80% by volume.

[0013] [Inorganic Filler] The filler of the present disclosure preferably contains an inorganic filler and a resin. Examples of the inorganic filler used in the present disclosure include barium titanate, strontium titanate, calcium titanate, magnesium titanate, bismuth titanate, zirconium titanate, zinc titanate, titanium dioxide, magnesium oxide, alumina, tantalum pentoxide, and niobium pentoxide.

[0014] The inorganic filler preferably contains at least one selected from the group consisting of barium titanate, strontium titanate, calcium titanate, magnesium titanate, bismuth titanate, zirconium titanate, zinc titanate, titanium dioxide, magnesium oxide, alumina, tantalum pentoxide, and niobium pentoxide. The inorganic filler may also be one that has been fired with the addition of a dopant compound containing another element. Such fired inorganic fillers may be able to increase the dielectric constant. In particular, from the viewpoint of a high dielectric constant and a low dielectric loss tangent, the inorganic filler is preferably barium titanate, titanium oxide, strontium titanate, calcium titanate, or zirconium titanate. Two or more types of inorganic fillers may be used in combination. Commercially available inorganic fillers can be used.

[0015] The inorganic filler preferably has a relative dielectric constant of 1 to 20,000 at 25°C and a measurement frequency of 10 GHz. For applications requiring a high dielectric constant, the relative dielectric constant of the inorganic filler is more preferably 6 to 20,000, and even more preferably 20 to 20,000. For applications requiring a low dielectric constant, the relative dielectric constant of the inorganic filler is more preferably 1 to 6, and even more preferably 1 to 4. Furthermore, from the viewpoint of achieving both the orientation state and dielectric properties of the inorganic filler, the average particle size of the inorganic filler is preferably 0.01 μm to 50 μm, more preferably 0.05 μm to 30 μm, and particularly preferably 0.1 μm to 20 μm. The inorganic filler may be a mixture of two or more types of fillers having different average particle sizes.

[0016] The shape of the inorganic filler is not particularly limited, and may be amorphous, spherical, or elliptical. Among these, the inorganic filler is preferably spherical. When the inorganic filler is spherical, the content in the resin composition can be increased, and the dielectric constant can be further increased.

[0017] One or more types of inorganic fillers can be used. From the viewpoint of achieving both dielectric properties and mechanical properties, the content of the inorganic filler is preferably 1% by volume to 95% by volume, and more preferably 10% by volume to 60% by mass, relative to the total amount of the film. When using a mixture of two or more fillers with different average particle sizes, or when using spherical fillers, the content of the inorganic filler is preferably 10% by volume to 80% by volume. The inorganic filler may also be surface-treated with an inorganic or organic substance. Examples of surface treatment methods include (1) modification by coating, (2) topochemical modification, (3) modification by mechanochemical reaction, (4) modification by encapsulation, and (5) combined use of radiation exposure.

[0018] [Organic Filler] The filler of the present disclosure preferably contains an organic filler and a resin. As the organic filler, known organic fillers can be used. Examples of materials for the organic filler include polyethylene, polystyrene, urea-formalin filler, polyester, cellulose, acrylic resin, fluororesin, cured epoxy resin, crosslinked benzoguanamine resin, crosslinked acrylic resin, liquid crystal polymer (LCP), and materials containing two or more of these.

[0019] In particular, from the viewpoint of reducing the dielectric loss tangent of the film, the organic filler preferably contains at least one selected from the group consisting of liquid crystal polymers, fluororesins, elastomers, and polyethylene, and more preferably contains at least one selected from the group consisting of liquid crystal polyesters, polytetrafluoroethylene, polystyrene-based elastomers, and polyethylene.

[0020] The organic filler preferably has a relative dielectric constant at 25°C and a measurement frequency of 10 GHz of 1 to 6, more preferably 1 to 4. From the viewpoint of achieving both an orientation state and dielectric properties of the organic filler, the average particle size of the organic filler is preferably 0.01 μm to 10 μm, more preferably 0.02 μm to 2 μm, and particularly preferably 0.03 μm to 5 μm.

[0021] The shape of the organic filler is not particularly limited, and may be amorphous, spherical, or elliptical. Among these, a spherical organic filler is preferred. When the organic filler is spherical, the content in the resin composition can be increased, and the dielectric constant can be further increased.

[0022] One or more organic fillers can be used. From the viewpoint of achieving both dielectric properties and mechanical properties, the content of the organic filler is preferably 1 to 95% by volume, and more preferably 10 to 60% by mass, relative to the total amount of the film. When a mixture of two or more fillers with different average particle sizes is used, or when a spherical filler is used, the content of the organic filler is preferably 10 to 80% by volume.

[0023] [Resin] Examples of the resin used in the present disclosure include thermoplastic resins, thermoplastic elastomers, thermosetting resins, semi-cured or cured products of photocurable resins, thermosetting elastomers, semi-cured or cured products of photocurable elastomers, etc. A curing agent (initiator) or a curing accelerator can be added to these resins as needed.

[0024] The resin preferably includes at least one selected from the group consisting of a thermoplastic resin, a thermoplastic elastomer, a semi-cured product of a thermosetting resin, a cured product of a thermosetting resin, a semi-cured product of a thermosetting elastomer, and a cured product of a thermosetting elastomer.

[0025] Examples of thermoplastic resins include polyester resins (including liquid crystal polymers), cyanate resins, coumarone resins, polyurethane 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.

[0026] 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.

[0027] 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.

[0028] Examples of thermosetting resins include epoxy resins, which are monomers, oligomers, or polymers having two or more epoxy groups in one molecule, phenolic resins, melamine resins, urea resins, unsaturated polyester resins, alkyd resins, urethane resins, polyimide resins such as bismaleimide resins, polyamide resins, polyamideimide resins, silicone resins, and acrylic resins, and the molecular weight and molecular structure thereof are not particularly limited. From the viewpoint of moldability and electrical properties, at least one selected from the group consisting of epoxy resins and polyimide resins is preferred, at least one selected from the group consisting of epoxy resins and bismaleimide resins is more preferred, and an epoxy resin is even more preferred.

[0029] Specific examples of epoxy resins include biphenyl-type epoxy resins; bisphenol-type epoxy resins such as bisphenol A-type epoxy resins, bisphenol F-type epoxy resins, and tetramethylbisphenol F-type epoxy resins; stilbene-type epoxy resins; novolac-type epoxy resins such as phenol novolac-type epoxy resins and cresol novolac-type epoxy resins; polyfunctional epoxy resins such as triphenolmethane-type epoxy resins and alkyl-modified triphenolmethane-type epoxy resins; aralkyl-type epoxy resins such as phenol aralkyl-type epoxy resins having a phenylene skeleton and phenol aralkyl-type epoxy resins having a biphenylene skeleton; naphthol-type epoxy resins such as dihydroxynaphthalene-type epoxy resins and epoxy resins obtained by glycidyl etherifying a dihydroxynaphthalene dimer; triazine-nucleus-containing epoxy resins such as triglycidyl isocyanurate and monoallyl diglycidyl isocyanurate; and bridged cyclic hydrocarbon compound-modified phenol-type epoxy resins such as dicyclopentadiene-modified phenol-type epoxy resins. These may be used alone or in combination of two or more.

[0030] Among these, from the viewpoint of improving the balance between moisture resistance reliability and moldability, the epoxy resin preferably contains one or more types selected from the group consisting of bisphenol-type epoxy resins, novolac-type epoxy resins, biphenyl-type epoxy resins, phenol aralkyl-type epoxy resins, and triphenolmethane-type epoxy resins, and more preferably contains at least one type selected from the group consisting of biphenyl-type epoxy resins and phenol aralkyl-type epoxy resins.

[0031] Furthermore, it may contain a curing agent that reacts with the epoxy resin to cure it, and examples thereof include amines such as linear aliphatic diamines having 2 to 20 carbon atoms, such as ethylenediamine, trimethylenediamine, tetramethylenediamine, and hexamethylenediamine, metaphenylenediamine, paraphenylenediamine, paraxylenediamine, active ester compounds, 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylpropane, 4,4'-diaminodiphenylether, 4,4'-diaminodiphenylsulfone, 4,4'-diaminodicyclohexane, bis(4-aminophenyl)phenylmethane, 1,5-diaminonaphthalene, metaxylenediamine, paraxylenediamine, 1,1-bis(4-aminophenyl)cyclohexane, and dicyanodiamide; resole-type phenolic resins, such as aniline-modified resole resins and dimethyl ether resole resins; phenol novolac resins, cresol novolac resins, and tert-butylphenol novolac resins. Examples of suitable phenolic resins include novolac-type phenolic resins such as phenolic aralkyl resins and nonylphenol novolac resins; polyfunctional phenolic resins such as trisphenolmethane-type phenolic resins; phenol aralkyl resins such as phenylene skeleton-containing phenol aralkyl resins and biphenylene skeleton-containing phenol aralkyl resins; phenolic resins having a condensed polycyclic structure such as a naphthalene skeleton or an anthracene skeleton; polyoxystyrenes such as polyparaoxystyrene; acid anhydrides including alicyclic acid anhydrides such as hexahydrophthalic anhydride (HHPA) and methyltetrahydrophthalic anhydride (MTHPA), and aromatic acid anhydrides such as trimellitic anhydride (TMA), pyromellitic anhydride (PMDA), and benzophenonetetracarboxylic acid (BTDA); polymercaptan compounds such as polysulfides, thioesters, and thioethers; isocyanate compounds such as isocyanate prepolymers and blocked isocyanates; organic acids such as carboxylic acid-containing polyester resins; and polyaminoamides. These may be used alone or in combination of two or more.

[0032] The curing agent is not particularly limited, and can be selected as a compound that initiates the curing reaction depending on the type of curable resin, the desired properties of the molding resin composition, and the like. As the curing agent, one known thermal initiator or photoinitiator may be used, or two or more known thermal initiators may be used in combination. The curing agent preferably contains at least one active ester compound. Two or more known active ester compounds may be used in combination. Here, the active ester compound refers to a compound that has one or more ester groups in one molecule that react with epoxy groups and has the ability to cure epoxy resins. When the curing agent contains an active ester compound, the curing agent may or may not contain a curing agent other than the active ester compound.

[0033] The use of an active ester compound as a curing agent can reduce the dielectric dissipation factor of the cured product compared to the use of other curing agents. The reaction between an epoxy resin and a phenolic or amine curing agent generates secondary hydroxyl groups. In contrast, the reaction between an epoxy resin and an active ester compound generates ester groups instead of secondary hydroxyl groups. Because ester groups have lower polarity than secondary hydroxyl groups, molding resin compositions containing an active ester compound as a curing agent can reduce the dielectric dissipation factor of the cured product compared to molding resin compositions containing only a curing agent that generates secondary hydroxyl groups. Furthermore, while polar groups in a cured product increase the water absorption of the cured product, using an active ester compound as a curing agent can reduce the concentration of polar groups in the cured product, thereby reducing the water absorption of the cured product. Furthermore, reducing the water absorption of the cured product, i.e., reducing the content of water molecules, which are polar molecules, can further reduce the dielectric dissipation factor of the cured product.

[0034] The type of active ester compound is not particularly limited as long as it is a compound having one or more ester groups in the molecule that react with an epoxy group, and examples thereof include phenol ester compounds, thiophenol ester compounds, N-hydroxyamine ester compounds, and esterified products of heterocyclic hydroxy compounds.

[0035] The equivalent ratio (ester group / epoxy group) between the epoxy resin and the active ester compound is preferably 0.9 or more, more preferably 0.95 or more, and even more preferably 0.97 or more, from the viewpoint of keeping the dielectric loss tangent of the cured product low. The equivalent ratio (ester group / epoxy group) between the epoxy resin and the active ester compound is preferably 1.1 or less, more preferably 1.05 or less, and even more preferably 1.03 or less, from the viewpoint of keeping the unreacted active ester compound low.

[0036] The amount of the curing agent added is not particularly limited, but for example, when the entire resin composition is taken as 100% by mass, it is preferably 0.1% by mass to 20% by mass, more preferably 0.5% by mass to 10% by mass or less, and even more preferably 1% by mass to 5% by mass.

[0037] The semi-cured product of the thermosetting resin and the cured product of the thermosetting resin are preferably those obtained by semi-curing and curing the above-mentioned thermosetting resin, respectively.

[0038] Examples of the thermosetting elastomer include curable elastomers such as silicone rubber, fluororubber, and urethane rubber.

[0039] Examples of silicone rubbers include vinyl group-containing organopolysiloxanes, etc. The semi-cured thermosetting elastomer and the cured thermosetting elastomer are preferably the semi-cured and cured products of the above-mentioned thermosetting resins, respectively.

[0040] The curing accelerator is not particularly limited, and can be selected as a compound that accelerates the curing reaction depending on the type of curable resin, the desired properties of the molding resin composition, etc. Two or more types of curing accelerators may be used in combination.

[0041] In particular, the resin preferably contains a liquid crystal polymer.

[0042] 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.

[0043] 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.

[0044] 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.

[0045] 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.

[0046] The liquid crystal polymer is preferably a wholly aromatic liquid crystal polymer made using only aromatic compounds as raw material monomers.

[0047] 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.

[0048] 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.

[0049] 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.

[0050] 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.

[0051] 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.

[0052] The aromatic polyesteramide is preferably a crystalline polymer. The first phase preferably contains a crystalline aromatic polyesteramide. The crystalline aromatic polyesteramide further reduces the dielectric loss tangent. A crystalline polymer refers to one 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.

[0053] 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.

[0054] 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.

[0055] 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.

[0056] 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.

[0057] 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.

[0058] 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 constitutional unit derived from 4'-hydroxy-4-biphenylcarboxylic acid.

[0059] 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.

[0060] 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.

[0061] In formula 3, Ar ３ is preferably a p-phenylene group or a 4,4'-biphenylylene group, and more preferably a p-phenylene group.

[0062] 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.

[0063] 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.

[0064] 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.

[0065] 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.

[0066] The aromatic polyesteramide is preferably produced by melt-polymerizing raw material monomers corresponding to the structural units that constitute the aromatic polyesteramide.

[0067] 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.

[0068] The resin content of the film may be one type or two or more types. From the viewpoint of achieving both dielectric properties and mechanical properties, the resin content is preferably 10 to 90% by volume, more preferably 20 to 70% by volume, and even more preferably 30 to 60% by volume.

[0069] The film may contain additives in addition to the inorganic filler and resin. Examples of additives include polymerization initiators, dispersants, surfactants, crosslinking agents, antioxidants, flame retardants, dielectric loss tangent reducers, colorants, and stress relaxation agents. Two or more types of additives may be used in combination.

[0070] <Film Structure> The film of the present disclosure preferably includes a plurality of layers A containing 50% by volume or more of the filler and a layer B containing the resin, and the plurality of layers A and layer B are arranged in the same plane so as not to contact each other. The filler is at least one type selected from the group consisting of inorganic fillers and organic fillers. When the filler is an inorganic filler, the film of the present disclosure preferably includes a plurality of layers A containing 50% by volume or more of the inorganic filler and a layer B containing the resin, and the plurality of layers A and layer B are arranged in the same plane so as not to contact each other.

[0071] The content of the filler in Layer A is preferably 50% by volume or more, more preferably 70% by volume or more, and even more preferably 80% by volume or more, relative to the total amount of Layer A. The upper limit of the filler content is not particularly limited and may be, for example, 100% by volume. When the filler is an inorganic filler, the content of the inorganic filler in Layer A is preferably 50% by volume or more, more preferably 70% by volume or more, and even more preferably 80% by volume or more, relative to the total amount of Layer A. The upper limit of the inorganic filler content is not particularly limited and may be, for example, 100% by volume.

[0072] Layer A preferably contains the above resin in addition to the above filler.

[0073] The content of the resin in Layer B is preferably 60% by volume or more, more preferably 80% by volume or more, and even more preferably 90% by volume or more, based on the total amount of Layer B. The content of the resin may be 100% by volume.

[0074] The shape of Layer A is not particularly limited, and may be square, rectangular, polygonal, or irregular in plan view of the film. Furthermore, the shape of Layer A may be square, rectangular, or trapezoid in cross section of the film cut along the thickness direction.

[0075] The arrangement of the plurality of layers A is not particularly limited, and the adjacent layers A may be aligned at a certain distance from each other, or may be in a mosaic or honeycomb pattern.

[0076] The width of layer A is not particularly limited, but is preferably 100 μm to 400 μm, and more preferably 200 μm to 300 μm.

[0077] The width of Layer A is measured by the following method. The film is cut in the thickness direction using a microtome. The cut surface is observed using an optical microscope or a scanning electron microscope, and the width of Layer A is measured. When Layer A is irregular, the width refers to the length of the longest part of Layer A that is parallel to the film plane. The width of Layer A is measured at 10 random locations and used as the average value.

[0078] The distance between adjacent layers A (hereinafter also referred to as "distance between layers A") is not particularly limited, but is preferably 5 μm to 100 μm, and more preferably 30 μm to 70 μm.

[0079] The distance between layers A is measured by the following method. The film is cut in the thickness direction of the film using a microtome. The cut surface is observed using an optical microscope or a scanning electron microscope. The distance between two adjacent layers A is measured. The distance between layers A is the average value of values ​​measured at 10 random locations.

[0080] The average thickness of Layer A and Layer B is not particularly limited, but is preferably 5 μm to 80 μm, more preferably 10 μm to 50 μm, and particularly preferably 20 μm to 40 μm.

[0081] The film of the present disclosure preferably further includes a resin layer C, and the resin layer C is in contact with the layer A and the layer B. That is, it is preferable that no other layer is interposed between the layer A and the layer B and the resin layer C.

[0082] The resin layer C may be disposed on one surface of the layer A or the layer B, or may be disposed on both surfaces of the layer A and the layer B.

[0083] The resin layer C contains a resin. The resin contained in the resin layer C is not particularly limited, and may be the same as or different from the resin contained in the layer B.

[0084] The average thickness of the resin layer C is not particularly limited, but is preferably 0.3 μm to 10 μm, more preferably 0.5 μm to 5 μm, and even more preferably 0.5 μm to 2 μm. When the resin layer C is disposed on both the surface of the layer A and the surface of the layer B, the average thickness of the resin layer C means the average value of the total thickness of the two resin layers C.

[0085] <Film Properties> (Number of Fillers per Unit Area) The number of fillers per unit area in the in-plane direction (Di) and the number of fillers per unit area in the thickness direction (Do) of the film of the present disclosure can be determined by preparing a cut surface using a microtome as needed and evaluating the number of fillers per unit area through morphological observation using a scanning electron microscope. The ratio (Do / Di) is calculated from the obtained Di and Do. When the filler is an inorganic filler, the number of inorganic fillers per unit area in the in-plane direction (Di) and the number of inorganic fillers per unit area in the thickness direction (Do) of the film of the present disclosure can be determined by preparing a cut surface using a microtome as needed and evaluating the number of inorganic fillers per unit area through morphological observation using a scanning electron microscope. The ratio (Do / Di) is calculated from the obtained Di and Do.

[0086] For example, when a filler (e.g., an inorganic filler) is oriented in the in-plane direction, Di tends to increase and Do tends to decrease, resulting in a decrease in Do / Di. When a filler (e.g., an inorganic filler) is oriented in the film thickness direction, Di tends to decrease and Do tends to increase, resulting in an increase in Do / Di. In the present disclosure, the relative dielectric constant and dielectric loss tangent can be set within suitable ranges by controlling the orientation state of the filler (e.g., an inorganic filler) in the liquid preparation process or film formation process described below so that Do / Di is 0.5 or more. Do / Di is preferably 0.7 to 1,000, more preferably 0.85 to 100, and even more preferably 0.9 to 10.

[0087] When Do / Di is 0.5 or more, the filler (e.g., inorganic filler) is appropriately oriented in the thickness direction. As a result, the amount of dielectric in the electric field direction increases, efficiently increasing the relative dielectric constant in the electric field direction, and at the same time, the amount of dielectric in the direction perpendicular to the electric field decreases, efficiently lowering the relative dielectric constant in the direction perpendicular to the electric field. On the other hand, since the dielectric loss tangent changes depending on the amount of filler (e.g., inorganic filler) added, by promoting the orientation of the filler (e.g., inorganic filler) in the thickness direction, the relative dielectric constant and dielectric loss tangent fall within suitable ranges.

[0088] (Dielectric Properties) The film of the present disclosure preferably has a relative dielectric constant of 5 to 1,000 or 1 to 5, and more preferably 10 to 100 or 1 to 3.

[0089] In the present disclosure, the dielectric constant and dielectric loss tangent are 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 film is inserted into the cavity resonator, and the change in resonance frequency before and after insertion for 96 hours is measured in an environment of 25°C temperature and 60% RH.

[0090] (Thickness) The average thickness of the film is not particularly limited, but is preferably 5 μm to 500 μm, more preferably 10 μm to 300 μm, and particularly preferably 15 μm to 100 μm.

[0091] The average thickness of the film is determined by measuring any five points using an adhesive film thickness meter, for example, an electronic micrometer (product name "KG3001A", manufactured by Anritsu Corporation), and averaging these values.

[0092] (Surface Roughness) The surface roughness of the film is preferably 5 μm or less, more preferably 3 μm or less. There is no particular lower limit to the surface roughness of the film, and it is, for example, 0.0001 μm.

[0093] When the surface roughness of the film is 5 μm or less, the transmission loss of high frequency signals can be further reduced.

[0094] The surface roughness of the film can be determined by observing the surface using a laser microscope and evaluating the root mean square of the roughness over a reference length.

[0095] <Film Production Process> (Film Formation) The method for producing the film is not particularly limited, and known methods can be used.

[0096] Suitable film-forming methods include, for example, co-casting, multi-layer coating, and co-extrusion, and the film can also be produced using a dispenser or the like.

[0097] 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 solution in which the components of each layer are dissolved or dispersed in a solvent.

[0098] The film production process preferably includes a step of preparing a solution by dispersing using a bead mill, and a step of forming a film using the solution.

[0099] Dispersion treatment using a bead mill reduces particle agglomerates and achieves uniformity. The diameter of the beads used in the bead mill is preferably larger than the average particle size of the particles used to prepare the solution. The diameter of the beads is, for example, 0.1 mm to 5 mm.

[0100] 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.

[0101] 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.

[0102] 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 the liquid crystal polymer, 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.

[0103] 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. It is preferable to use a compound having a boiling point of 220°C or lower at 1 atmosphere as the aprotic compound.

[0104] In the film production process, when the film is produced by the above-mentioned co-casting method, multi-layer coating method, co-extrusion method, or the like, a support may be used.

[0105] 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.

[0106] 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.

[0107] 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.

[0108] (Stretching) In the film production process, stretching can be appropriately combined from the viewpoint of controlling molecular orientation and adjusting the thermal expansion coefficient and mechanical properties. The stretching method is not particularly limited, and known methods can be referred to. It 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, or by utilizing autogenous shrinkage due to drying without stretching. Stretching is particularly effective for improving breaking elongation and breaking strength when the mechanical properties of the film are reduced by the addition of inorganic fillers, etc.

[0109] In the present disclosure, when a curable resin is used, the resin may be impregnated into a fiber substrate and then used as a semi-cured sheet (prepreg). Such a sheet has excellent properties such as dielectric properties and mechanical and electrical connection reliability under high temperature and humidity, and is suitable for producing an insulating layer of a printed wiring board.

[0110] The method for impregnating the resin composition into the fiber substrate is not particularly limited, but examples include a method in which the resin composition is dissolved in a solvent to prepare a resin varnish and the fiber substrate is immersed in the resin varnish, a method in which the resin varnish is applied to the fiber substrate using various coaters, a method in which the resin varnish is sprayed onto the fiber substrate using a sprayer, and a method in which both sides of the fiber substrate are laminated with the resin film made of the resin composition.

[0111] Examples of the fiber substrate include glass fiber substrates such as woven glass cloth and nonwoven glass cloth, inorganic fiber substrates such as woven or nonwoven cloth containing an inorganic compound other than glass as a component, and organic fiber substrates made of organic fibers such as aromatic polyamideimide resin, polyamide resin, aromatic polyester resin, polyester resin, polyimide resin, fluororesin, etc. Among these substrates, the use of a glass fiber substrate typified by woven glass cloth in terms of strength can improve the mechanical strength and heat resistance of the printed wiring board.

[0112] The thickness of the fiber substrate is not particularly limited, but is preferably 5 μm to 150 μm, more preferably 10 μm to 100 μm, and even more preferably 12 μm to 90 μm.

[0113] When the thickness of the fiber substrate is equal to or less than the upper limit, the impregnation of the resin composition in the fiber substrate is improved, the occurrence of strand voids and a decrease in insulation reliability can be suppressed, and the formation of through-holes by laser can be facilitated. Furthermore, when the thickness of the fiber substrate is equal to or greater than the lower limit, the strength of the fiber substrate and prepreg can be improved, which is effective in terms of handleability, ease of prepreg preparation, suppression of warpage of the resin substrate, etc. As the glass fiber substrate, for example, a glass fiber substrate formed from one or more types of glass selected from E glass, S glass, D glass, T glass, NE glass, UT glass, L glass, HP glass, and quartz glass is preferably used.

[0114] Prepregs can be used, for example, to form insulating layers in build-up layers or core layers in printed wiring boards. When using prepregs to form insulating layers in core layers in printed wiring boards, for example, two or more prepregs can be stacked and the resulting laminate can be heat-cured to form an insulating layer for the core layer.

[0115] <Metal Layer> The metal layer may be, for example, a rolled metal foil formed by a rolling method, an electrolytic metal foil formed by an electrolytic method, a plated metal foil, a sputtered metal foil, or the like.

[0116] The metal layer may be made of a conventionally known material, and is preferably made of silver or copper, and more preferably made of copper.

[0117] Metal layers may be disposed on both sides of a film (including a prepreg). In this case, the two metal layers may be metal layers of the same material, thickness, and shape, or metal layers of different materials, thicknesses, and shapes. From the viewpoint of adjusting the characteristic impedance, the two metal layers may be metal substrates of different materials and thicknesses. This allows a metal-clad laminate to be produced.

[0118] The average thickness of the metal layer is not particularly limited, but is preferably 0.01 μm to 20 μm, more preferably 0.1 μm to 18 μm, and even more preferably 1 μm to 12 μm.

[0119] <Printed Wiring Board> A printed wiring board can be produced from the above metal-clad laminate by a known method, and can also be applied to a semiconductor package as appropriate.

[0120] <Antenna Substrate> A pattern antenna can be produced from the above-mentioned metal-clad laminate or printed wiring board by a known method such as photofabrication. The corresponding frequency of the antenna can be appropriately adjusted by designing the size of the pattern or patch.

[0121] <Antenna Module> The antenna module including the antenna substrate may be an antenna module that transmits and receives at least one of radio waves having a frequency of 6 to 24 GHz, or may be an antenna module that transmits and receives at least one of radio waves having a frequency of 0.5 to 5.9 GHz. The antenna module including the antenna substrate is preferably an antenna module that transmits and receives radio waves having a frequency of 6 to 24 GHz, and more preferably an antenna module that transmits and receives radio waves having a frequency of 0.5 to 5.9 GHz.

[0122] <Metamaterial> A metamaterial can be produced by forming a pattern composed of at least one of a conductive material and a material that changes from a non-conductor to a conductor on at least one surface of the film or metal-clad laminate described above. The pattern preferably acts as a resonator for electromagnetic waves with a frequency of 6 to 24 GHz.

[0123] The conductive material preferably contains a metal, and more preferably is one or more selected from the group consisting of gold, silver, platinum, copper, and aluminum.

[0124] The content of the metal relative to the total mass of the conductive material is not particularly limited, and may be 80 mass % or more, 90 mass % or more, or even 100 mass %.

[0125] The material that changes from a non-conductor to a conductor can be a material that changes from a non-conductor to a conductor by heating, irradiating with light, or applying a voltage, and is preferably one or more selected from the group consisting of phase-change materials, semiconductors, conductive oxides, and carbon materials.

[0126] In the present disclosure, a phase change material refers to a material that undergoes a phase change between an amorphous phase and a crystalline phase due to Joule heating caused by an electric pulse.

[0127] Examples of phase change materials include vanadium oxide, antimony tellurium (SbTe) alloy, germanium tellurium (GeTe) alloy, germanium antimony tellurium (GeSbTe) alloy, indium antimony tellurium (InSbTe) alloy, silver indium antimony tellurium (AgInSbTe) alloy, etc. Among these, vanadium oxide or GeSbTe alloy is preferred from the viewpoint of easily controlling the temperature and voltage at which it changes from a non-conductor to a conductor, and from the viewpoint of crack suppression.

[0128] Examples of semiconductors include p-type π-conjugated polymers, condensed polycyclic compounds, triarylamine compounds, hetero five-membered ring compounds, phthalocyanine compounds, and porphyrin compounds.

[0129] Examples of conductive oxides include indium tin oxide (ITO), indium zinc oxide (IZO), zinc oxide (ZnO), and indium gallium zinc oxide (IGZO). Examples of carbon materials include carbon nanotubes and graphene. The pattern may include a plurality of structures. The pattern may include two or more types of structures that differ in shape, size, etc.

[0130] <Electromagnetic Wave Absorbing Film> Furthermore, in a metamaterial using a high dielectric constant film according to the present disclosure, a reflective layer may be formed on the surface opposite to the surface on which a pattern is formed, and the thickness of the film (unit: μm) may be set to a value obtained by multiplying the wavelength of an electromagnetic wave having a frequency of 6 to 24 GHz by 0.25 and dividing the result by the square root of the dielectric constant of the film, thereby making it possible to prepare an electromagnetic wave absorbing film that is relatively thin and has excellent brittleness and tracking properties.

[0131] <Laminated Film> The above films can be laminated together so that they are in contact with each other to produce a laminated film. The method for bonding the films together is not particularly limited, and examples thereof include a lamination method.

[0132] 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.

[0133] <<Examples 1A to 8A, Comparative Example 1>> Details of the materials used to prepare the films and laminates are as follows.

[0134] <Inorganic fillers> F1: Pulverized barium titanate (average particle size 0.18 μm, relative dielectric constant 200, dielectric dissipation factor 0.015) F2: Pulverized strontium titanate (average particle size 1 μm, relative dielectric constant 300, dielectric dissipation factor 0.0005) F3: Pulverized titanium oxide (average particle size 5 μm, relative dielectric constant 90, dielectric dissipation factor 0.001) F4: Pulverized calcium titanate (average particle size 5 μm, relative dielectric constant 200, dielectric dissipation factor 0.001) F5: Hollow silica particles (product name "Glass Bubbles iM16K", manufactured by 3M, average particle size 20 μm, relative dielectric constant 1.5, dielectric dissipation factor 0.005)

[0135] <Organic Filler> F6: Polytetrafluoroethylene particles (average particle size 10 μm, relative dielectric constant 1.9, dielectric dissipation factor 0.0001) prepared according to the following production method.

[0136] 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. Then, TFE was added again and the pressure inside the tank was adjusted to 0.8 MPa. ２ O ammonium persulfate and 250 ppm / H ２ Disuccinic 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 F6. The weight-average molecular weight of the obtained PTFE particles was 5,000 and the average particle size was 10 μm.

[0137] F7: Hydrogenated styrene-isobutylene-styrene block copolymer particles (average particle size 10 μm, relative dielectric constant 2.3, dielectric dissipation factor 0.0001) prepared according to the following production method. 452 mL of 1-chlorobutane, 319 mL of hexane, and 0.55 g of 1,4-bis(1-chloro-1-methylethyl)benzene were placed in a reaction vessel and cooled to -75°C. Then, 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. The contents of the reactor were then poured into water and the organic and aqueous layers 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 mixture was pulverized using a grinder to obtain powdered hydrogenated styrene-isobutylene-styrene block copolymer F7. The hydrogenated styrene-isobutylene-styrene block copolymer F7 had a weight average molecular weight of 900 and an average particle size of 10 μm.

[0138] <Resins> P1: Aromatic polyesteramide prepared according to the following production method

[0139] -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 dielectric dissipation factor of the aromatic polyesteramide P1 was 0.003.

[0140] P2: Commercially available epoxy resin (product name "jER-807", manufactured by Mitsubishi Chemical Corporation) P3: Commercially available cyanate resin (product name "CYTESTER P-201", manufactured by Mitsubishi Gas Chemical Company, Inc.)

[0141] <Curing agent> K1: Commercially available activated ester resin (product name "Epicron HPC-8000-65T", manufactured by DIC Corporation) K2: Commercially available phenolic curing agent, aralkyl phenolic resin (product name "MEH7800 series", manufactured by Meiwa Kasei Co., Ltd.)

[0142] <Copper foil> M1: Product name "CF-T49A-DS-18", manufactured by Fukuda Metal Foil & Powder Co., Ltd., average thickness 18 μm (film formed on the treated side)

[0143] <Film Formation> The inorganic filler and resin shown in Table 1 were mixed in the amounts (mass %) shown in Table 1, and dispersed in a bead mill to obtain a solution (dispersion).

[0144] The resulting solution was sent to a slot die and applied to the copper foil shown in Table 1, adjusting the flow rate so that the average thickness after drying was the thickness shown in Table 1. The solvent was removed from the coating by hot air drying to obtain a polymer film (single-sided copper-clad laminate) having a copper layer. Furthermore, a single-sided copper-clad laminate was produced by heating the film from 50°C to 300°C at a rate of 1°C / min under a nitrogen atmosphere and holding it at 300°C for 2 hours. The Do / Di ratio was adjusted to the value shown in Table 1 based on the solids concentration of the solution, dispersion conditions, and hot air drying conditions.

[0145] [Preparation of double-sided copper-clad laminate] Another copper foil shown in Table 1 was prepared, and the film side of the above single-sided copper-clad laminate was laminated 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 double-sided copper-clad laminate. Further, the obtained double-sided copper-clad laminate was thermocompression bonded at 320 ° C and 4 MPa using a thermocompression bonding machine (product name "MP-SNL", manufactured by Toyo Seiki Seisakusho, Ltd.) to prepare a double-sided copper-clad laminate.

[0146] <<Evaluation>> The single-sided copper-clad laminates and double-sided copper-clad laminates thus produced were subjected to the following measurements and evaluations. The results are shown in Table 1.

[0147] <<Measurement Methods>> [Particle Density] The above single-sided copper-clad laminate and a sample cut with a microtome were prepared, and the density of the inorganic filler in the in-plane direction (Di) and the density of the inorganic filler in the thickness direction (Do) were determined by morphological observation using a scanning electron microscope. Furthermore, the ratio (Do / Di) was calculated and shown in Table 1.

[0148] [Dielectric Properties] The copper foil of a double-sided copper-clad laminate was removed with an aqueous solution of ferric chloride, washed with pure water, and dried to obtain a film. The dielectric constant 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 film was inserted into the cavity and measured for 96 hours at a temperature of 25°C and a humidity of 60% RH from the change in the resonant frequency. The dielectric constant and dielectric loss tangent of the film were measured.

[0149]

[0150] From Table 1, it can be seen that increasing Do / Di increases the relative dielectric constant.

[0151] [Antenna] Two sets of single-sided copper-clad laminates of Example 1A were prepared, and the film sides of the single-sided copper-clad laminates were pressed together using the aforementioned laminator and thermocompression bonding machine to produce a double-sided copper-clad laminate with a film thickness of 100 μm. Subsequently, the copper foil was patterned using a known subtractive method to produce a square microstrip antenna designed for a resonant frequency of 10 GHz. The single-sided copper-clad laminate of Comparative Example 1 was also processed in exactly the same way as the single-sided copper-clad laminate of Example 1A to produce a square microstrip antenna. The gain of both antennas was evaluated, and it was confirmed that Example 1A was superior.

[0152] [Metamaterial] Two sets of single-sided copper-clad laminates of Example 1A were prepared, and the film sides of the single-sided copper-clad laminates were pressed together using the aforementioned laminator and thermocompression bonding machine to produce a double-sided copper-clad laminate with a film thickness of 100 μm. Subsequently, the copper foil was patterned using a known subtractive method to form a metal pattern that selectively transmits near 6 GHz, thereby producing a metamaterial. The single-sided copper-clad laminate of Comparative Example 1 was also processed in exactly the same way as the single-sided copper-clad laminate of Example 1A to produce a metamaterial. When the frequency dependence of the transmission spectra near 6 GHz for both metamaterials was compared, it was confirmed that Example 1A had superior selectivity.

[0153] In addition, two sets of single-sided copper-clad laminates of Example 1A and a film in which the copper foil of each of the single-sided and double-sided copper-clad laminates had been etched and removed were prepared, and a double-sided copper-clad laminate with a film thickness of 650 μm was produced using the laminator and thermocompression bonding machine described above. Subsequently, one of the copper foils was patterned using a known subtractive method to form a metal pattern that resonates near 24 GHz, thereby producing a metamaterial. Furthermore, the single-sided copper-clad laminate of Comparative Example 1 and the film from which the copper foil had been removed were processed in exactly the same way to produce a metamaterial. When the electromagnetic wave absorption spectra of both metamaterials near 24 GHz were compared, it was confirmed that Example 1A had stronger absorption.

[0154] <<Examples 4 to 36>> Details of the materials used in producing the films and laminates are as follows: Materials that are the same as those in Example 1A etc. are omitted.

[0155] <Inorganic fillers> F2: pulverized strontium titanate (average particle size 1 μm, relative dielectric constant 300, dielectric dissipation factor 0.0005) F3: pulverized titanium oxide (average particle size 5 μm, relative dielectric constant 90, dielectric dissipation factor 0.001) F4: pulverized calcium titanate (average particle size 5 μm, relative dielectric constant 200, dielectric dissipation factor 0.001)

[0156] <Film Formation> (Examples 4 to 8, Examples 13 to 19, Examples 24 to 30, Examples 35, and 36) -Layer B- A solution of aromatic polyesteramide P1 was fed into a slot die and coated onto copper foil M1, adjusting the flow rate so that the thickness of Layer B after drying would be the thickness listed in Tables 2 to 4. The solvent was removed from the coating by hot air drying, yielding a polymer film (single-sided copper-clad laminate) having a copper layer. Further, a single-sided copper-clad laminate was produced by heating the laminate from 50°C to 300°C at a rate of 1°C / min under a nitrogen atmosphere and holding it at 300°C for 2 hours. Laser processing was performed on the resulting single-sided copper-clad laminate to form multiple recesses. The bottoms of the recesses were copper foil M1. The layout and size of the recesses were adjusted so that the width of Layer A and the distance between Layers A were the values ​​listed in Tables 2 to 4. As a result, Layer B was formed as convex portions on the copper foil M1.

[0157] -Layer A- The inorganic fillers and resins shown in Tables 2 to 4 were mixed in the contents (mass%) shown in Tables 2 to 4 and dispersed using a bead mill to obtain a solution (dispersion). The obtained solution was poured between Layer B and the substrate film, and the mixture was pressed with a laminator to fill the recesses with the solution. The substrate film was then peeled off and dried. The filling and drying were repeated until the recesses were filled with the resin and inorganic filler after drying. As a result, multiple Layers A and Layer B were arranged in the same plane, and the multiple Layers A were arranged so as not to contact each other. The substrate film is not particularly limited, and for example, a polyethylene terephthalate (PET) film can be used.

[0158] (Examples 9 to 11, Examples 20 to 22, Examples 31 to 33) -Layer A, Layer B-Layer A and layer B were formed in the same manner as in Example 1A.

[0159] -Layer C- A solution of aromatic polyesteramide P1 was fed into a slot die and coated onto Layer A and Layer B by adjusting the flow rate so that the thickness of Layer C after drying would be as shown in Tables 2 to 4. The solvent was removed from the coating by hot air drying, yielding a polymer film (single-sided copper-clad laminate) having a copper layer. Furthermore, Layer C was formed on one side of Layer A and Layer B by heating from 50°C to 300°C at a rate of 1°C / min in a nitrogen atmosphere and holding at 300°C for 2 hours. This resulted in the formation of copper foil M1, "Layer A and Layer B," and Layer C, in that order.

[0160] Examples 12, 23, and 34: Using the same method as in Example 9, a layer C was formed on one side of layer A and layer B. As a result, copper foil M1, "layer A and layer B," and layer C were formed in this order. Next, copper foil M1 was removed by etching with iron chloride. Thereafter, a layer C was formed on "layer A and layer B" on the side opposite to the side on which layer C was formed of a laminate in which "layer A and layer B" and layer C were stacked in this order, using the same method as in Example 9. As a result, layer C, "layer A and layer B," and layer C were formed in this order. Copper foil M1 was placed on one of the two layer Cs, and 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 single-sided copper-clad laminate. Furthermore, the obtained single-sided copper-clad laminate was subjected to thermocompression bonding under conditions of 320°C and 4 MPa using a thermocompression bonding machine (product name "MP-SNL", manufactured by Toyo Seiki Seisakusho Co., Ltd.), to produce a single-sided copper-clad laminate.

[0161] In Tables 2 to 4, "one side" in the column for the arrangement of Layer C means that Layer C was formed on one side of Layer A and Layer B. "both sides" means that Layer C was formed on both sides of Layer A and Layer B. Note that Do / Di was adjusted to the values ​​shown in Tables 2 to 4 using the solids concentration of the solution, dispersion conditions, and hot air drying conditions.

[0162] [Preparation of double-sided copper-clad laminate] Another copper foil M1 was prepared, and the film side of the above single-sided copper-clad laminate was laminated 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 double-sided copper-clad laminate. Further, using a thermocompression bonding machine (product name "MP-SNL", manufactured by Toyo Seiki Seisakusho Co., Ltd.), the obtained double-sided copper-clad laminate was thermocompression bonded at 320 ° C. and 4 MPa to produce a double-sided copper-clad laminate.

[0163] <<Measurement>> [Width of Layer A] The film was cut in the thickness direction of the film using a microtome. The cut surface was observed using an optical microscope or a scanning electron microscope to measure the width of Layer A. The width of Layer A was calculated by averaging the values ​​measured at 10 random locations.

[0164] [Distance between layers A] The film was cut in the thickness direction of the film using a microtome. The cut surface was observed using an optical microscope or a scanning electron microscope. The distance between two adjacent layers A was measured. The distance between layers A was calculated by averaging the values ​​measured at 10 random locations.

[0165] <<Evaluation>> [Dielectric Properties] The dielectric properties (dielectric constant and dielectric dissipation factor) of the film were measured in the same manner as in Example 1A. Based on the measurement results, the film was evaluated according to the following evaluation criteria. A: The dielectric constant was 30 or more and the dielectric dissipation factor was 0.005 or less. B: The dielectric constant was 10 or more and less than 30, or the dielectric dissipation factor was more than 0.005 and less than 0.01. C: The dielectric constant was 5 or more and less than 10, or the dielectric dissipation factor was more than 0.01 and less than 0.02.

[0166] [Mechanical Properties (Brittleness)] The obtained film was rolled into a cylindrical shape with a diameter of 50 mm, and visually observed for cracks or breakage. The evaluation criteria are as follows: A: No cracks occurred. B: Cracks occurred. C: Cracks occurred.

[0167]

[0168]

[0169]

[0170] As shown in Tables 2 to 4, the films of Examples 4 to 36 contain an inorganic filler and a resin, and have a ratio (Do / Di) of 0.5 or more, and therefore can achieve both a high dielectric constant and a low dielectric loss tangent. Comparisons between Example 7 and Example 8, between Example 18 and Example 19, and between Example 29 and Example 30 reveal that when the content of the inorganic filler in Layer A is 50% by volume or more, the dielectric properties are superior.

[0171] <<Examples 37 to 69>> Details of the materials used in producing the films and laminates are as follows: Materials that are the same as those in Example 1A etc. are omitted.

[0172] <Resin> In Examples 59 to 69, P2 and K1 were used in a mass ratio of 1:1.

[0173] <Film Formation> (Examples 37-41, Examples 46-52, Examples 57-63, Examples 68, 69) -Layer B- The resins listed in Tables 5-7 were fed into a slot die and coated onto copper foil M1, adjusting the flow rate so that the thickness of Layer B after drying would be the thickness listed in Tables 5-7. The solvent was removed from the coating by hot air drying, yielding a polymer film (single-sided copper-clad laminate) having a copper layer. Furthermore, single-sided copper-clad laminates were produced by heating the laminate from 50°C to 300°C at a rate of 1°C / min under a nitrogen atmosphere and holding it at 300°C for 2 hours. Laser processing was performed on the resulting single-sided copper-clad laminate to form multiple recesses. The bottoms of the recesses were copper foil M1. The layout and size of the recesses were adjusted so that the width of Layer A and the distance between Layers A were the values ​​listed in Tables 5-7. As a result, Layer B was formed as convex portions on copper foil M1.

[0174] -Layer A- The inorganic fillers and resins shown in Tables 5 to 7 were mixed in the contents (mass%) shown in Tables 5 to 7 and dispersed using a bead mill to obtain a solution (dispersion). The obtained solution was poured between Layer B and the substrate film, and the mixture was pressed with a laminator to fill the recesses with the solution. The substrate film was then peeled off and dried. The filling and drying were repeated until the resin and inorganic filler filled the recesses after drying. This resulted in multiple Layers A and B being arranged in the same plane, and multiple Layers A being arranged so as not to contact each other. The substrate film is not particularly limited, and for example, a polyethylene terephthalate (PET) film can be used.

[0175] (Examples 42 to 44, Examples 53 to 55, Examples 64 to 66) -Layer A, Layer B-Layer A and layer B were formed in the same manner as in Example 1A.

[0176] -Layer C- The resins listed in Tables 5 to 7 were fed into a slot die and coated onto Layer A and Layer B by adjusting the flow rate so that the thickness of Layer C after drying would be the thickness listed in Tables 5 to 7. The solvent was removed from the coating by hot air drying, yielding a polymer film (single-sided copper-clad laminate) having a copper layer. Furthermore, Layer C was formed on one side of Layer A and Layer B by heating from 50°C to 300°C at a rate of 1°C / min in a nitrogen atmosphere and holding at 300°C for 2 hours. This resulted in the formation of copper foil M1, "Layer A and Layer B," and Layer C, in that order.

[0177] Examples 45, 56, and 67: Using the same method as in Example 9, a layer C was formed on one side of layer A and layer B. As a result, copper foil M1, "layer A and layer B," and layer C were formed in this order. Next, copper foil M1 was removed by etching with iron chloride. Thereafter, a layer C was formed on "layer A and layer B" on the side opposite to the side on which layer C was formed of a laminate in which "layer A and layer B" and layer C were stacked in this order, using the same method as in Example 9. As a result, layer C, "layer A and layer B," and layer C were formed in this order. Copper foil M1 was placed on one of the two layer Cs, and 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 single-sided copper-clad laminate. Furthermore, the obtained single-sided copper-clad laminate was subjected to thermocompression bonding under conditions of 320°C and 4 MPa using a thermocompression bonding machine (product name "MP-SNL", manufactured by Toyo Seiki Seisakusho Co., Ltd.), to produce a single-sided copper-clad laminate.

[0178] In Tables 5 to 7, "one side" in the column for the arrangement of Layer C means that Layer C was formed on one side of Layer A and Layer B. "both sides" means that Layer C was formed on both sides of Layer A and Layer B. Note that Do / Di was adjusted to the values ​​shown in Tables 5 to 7 using the solids concentration of the solution, dispersion conditions, and hot air drying conditions.

[0179] [Preparation of double-sided copper-clad laminate] Another copper foil M1 was prepared, and the film side of the above single-sided copper-clad laminate was laminated 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 double-sided copper-clad laminate. Further, using a thermocompression bonding machine (product name "MP-SNL", manufactured by Toyo Seiki Seisakusho Co., Ltd.), the obtained double-sided copper-clad laminate was thermocompression bonded at 320 ° C. and 4 MPa to produce a double-sided copper-clad laminate.

[0180] The width of the layer A and the distance between the layers A were measured in the same manner as in Example 1 A. Furthermore, the dielectric properties and brittleness were evaluated in the same manner as in Example 1 A.

[0181]

[0182]

[0183]

[0184] As shown in Tables 5 to 7, the films of Examples 37 to 69 contained an inorganic filler and a resin, and had a ratio (Do / Di) of 0.5 or more, and therefore were able to achieve both a high dielectric constant and a low dielectric loss tangent. Comparisons between Example 40 and Example 41, between Example 51 and Example 52, and between Example 62 and Example 63 revealed that when the content of the inorganic filler in Layer A was 50 volume % or more, the dielectric properties were superior.

[0185] <<Examples 70 to 102>> Details of the materials used in producing the films and laminates are as follows: Materials that are the same as those in Example 1A etc. are omitted.

[0186] <Film Formation> (Examples 70-74, 79-85, 90-96, 101, 102) -Layer B- The resins listed in Tables 8-10 were fed into a slot die and coated onto copper foil M1, adjusting the flow rate so that the thickness of Layer B after drying would be the thickness listed in Tables 8-10. The solvent was removed from the coating by hot air drying, yielding a polymer film (single-sided copper-clad laminate) having a copper layer. Furthermore, single-sided copper-clad laminates were produced by heating the laminate from 50°C to 300°C at a rate of 1°C / min under a nitrogen atmosphere and holding it at 300°C for 2 hours. Laser processing was performed on the resulting single-sided copper-clad laminate to form multiple recesses. The bottoms of the recesses were copper foil M1. The layout and size of the recesses were adjusted so that the width of Layer A and the distance between Layers A were the values ​​listed in Tables 8-10. As a result, Layer B was formed as convex portions on copper foil M1.

[0187] -Layer A- The fillers and resins shown in Tables 8 to 10 were mixed in the contents (mass%) shown in Tables 8 to 10 and dispersed using a bead mill to obtain a solution (dispersion). The obtained solution was poured between Layer B and the substrate film, and the mixture was pressed with a laminator to fill the recesses with the solution. The substrate film was then peeled off and dried. The filling and drying were repeated until the recesses were filled with the resin and inorganic filler after drying. As a result, multiple Layers A and Layer B were arranged in the same plane, and the multiple Layers A were arranged so as not to contact each other. The substrate film is not particularly limited, and for example, a polyethylene terephthalate (PET) film can be used.

[0188] (Examples 75 to 77, Examples 86 to 88, Examples 97 to 99) -Layer A, Layer B-Layer A and layer B were formed in the same manner as in Example 1A.

[0189] -Layer C- The resins listed in Tables 8 to 10 were fed into a slot die and coated onto Layer A and Layer B by adjusting the flow rate so that the thickness of Layer C after drying would be the thickness listed in Tables 8 to 10. The solvent was removed from the coating by hot air drying, yielding a polymer film (single-sided copper-clad laminate) having a copper layer. Furthermore, Layer C was formed on one side of Layer A and Layer B by heating from 50°C to 300°C at a rate of 1°C / min in a nitrogen atmosphere and holding at 300°C for 2 hours. This resulted in the formation of copper foil M1, "Layer A and Layer B," and Layer C, in that order.

[0190] (Examples 78, 89, 100) Using the same method as in Example 9, a layer C was formed on one side of layer A and layer B. As a result, copper foil M1, "layer A and layer B," and layer C were formed in this order. Next, copper foil M1 was removed by etching with iron chloride. Thereafter, a layer C was formed on "layer A and layer B" on the side opposite to the side on which layer C was formed of a laminate in which "layer A and layer B" and layer C were stacked in this order, using the same method as in Example 9. As a result, layer C, "layer A and layer B," and layer C were formed in this order. Copper foil M1 was placed on one of the two layer Cs, and 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 single-sided copper-clad laminate. Furthermore, the obtained single-sided copper-clad laminate was subjected to thermocompression bonding under conditions of 320°C and 4 MPa using a thermocompression bonding machine (product name "MP-SNL", manufactured by Toyo Seiki Seisakusho Co., Ltd.), to produce a single-sided copper-clad laminate.

[0191] In Tables 8 to 10, "one side" in the column for the arrangement of Layer C means that Layer C was formed on one side of Layer A and Layer B. "both sides" means that Layer C was formed on both sides of Layer A and Layer B. Note that Do / Di was adjusted to the values ​​shown in Tables 8 to 10 using the solids concentration of the solution, dispersion conditions, and hot air drying conditions.

[0192] [Preparation of double-sided copper-clad laminate] Another copper foil M1 was prepared, and the film side of the above single-sided copper-clad laminate was laminated 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 double-sided copper-clad laminate. Further, using a thermocompression bonding machine (product name "MP-SNL", manufactured by Toyo Seiki Seisakusho Co., Ltd.), the obtained double-sided copper-clad laminate was thermocompression bonded at 320 ° C. and 4 MPa to produce a double-sided copper-clad laminate.

[0193] The width of layer A and the distance between layers A were measured in the same manner as in Example 1A.

[0194] <<Evaluation>> [Dielectric Properties] The dielectric properties (dielectric constant and dielectric dissipation factor) of the film were measured in the same manner as in Example 1A. Based on the measurement results, the film was evaluated according to the following evaluation criteria. A: The dielectric constant was 2 or less, and the dielectric dissipation factor was 0.005 or less. B: The dielectric constant was greater than 2 and less than 3, or the dielectric dissipation factor was greater than 0.005 and less than 0.01. C: The dielectric constant was greater than 3 and less than 5, or the dielectric dissipation factor was greater than 0.01 and less than 0.02.

[0195] [Mechanical Properties (Brittleness)] The obtained film was rolled into a cylindrical shape with a diameter of 50 mm, and visually observed for cracks or breakage. The evaluation criteria are as follows: A: No cracks occurred. B: Cracks occurred. C: Cracks occurred.

[0196]

[0197]

[0198]

[0199] As shown in Tables 8 to 10, the films of Examples 70 to 102 contained a filler and a resin and had a ratio (Do / Di) of 0.5 or more, and therefore achieved a relative dielectric constant of 1 to 5.

[0200] <<Examples 103 to 126>> -Layer A, Layer B-Layer A and layer B were formed in the same manner as in Example 1A.

[0201] -Layer C- A resin described in Table 11 was fed into a slot die and applied onto Layer A and Layer B by adjusting the flow rate so that the thickness of Layer C after drying would be the thickness described in Tables 8 to 10. The solvent was removed from the coating by hot air drying, yielding a polymer film (single-sided copper-clad laminate) having a copper layer. Furthermore, Layer C was formed on one side of Layer A and Layer B by heating from 50°C to 300°C at a rate of 1°C / min in a nitrogen atmosphere and holding at 300°C for 2 hours. This resulted in the formation of copper foil M1, "Layer A and Layer B," and Layer C, in that order.

[0202] Layer C was formed on one side of Layer A and Layer B using the same method as in Example 9. As a result, copper foil M1, "Layer A and Layer B," and Layer C were formed in this order. Next, copper foil M1 was removed by etching with iron chloride. Thereafter, Layer C was formed on "Layer A and Layer B" on the side opposite to the side on which Layer C was formed of the laminate in which "Layer A and Layer B" and Layer C were stacked in this order, using the same method as in Example 9. As a result, Layer C, "Layer A and Layer B," and Layer C were formed in this order. Copper foil M1 was placed on one of the two Layers C, and 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 single-sided copper-clad laminate. Furthermore, the obtained single-sided copper-clad laminate was subjected to thermocompression bonding under conditions of 320°C and 4 MPa using a thermocompression bonding machine (product name "MP-SNL", manufactured by Toyo Seiki Seisakusho Co., Ltd.), to produce a single-sided copper-clad laminate.

[0203] In Table 11, "one side" in the column for the arrangement of Layer C means that Layer C was formed on one side of Layer A and Layer B. "both sides" means that Layer C was formed on both sides of Layer A and Layer B. Note that Do / Di was adjusted to the value shown in Table 11 using the solids concentration of the solution, dispersion conditions, and hot air drying conditions.

[0204] [Preparation of double-sided copper-clad laminate] Another copper foil M1 was prepared, and the film side of the above single-sided copper-clad laminate was laminated 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 double-sided copper-clad laminate. Further, using a thermocompression bonding machine (product name "MP-SNL", manufactured by Toyo Seiki Seisakusho Co., Ltd.), the obtained double-sided copper-clad laminate was thermocompression bonded at 320 ° C. and 4 MPa to produce a double-sided copper-clad laminate.

[0205] The width of layer A, the distance between layers A, and the dielectric properties were measured in the same manner as in Example 9.

[0206] Transmission loss was measured for a microstrip line formed by applying resist to one side of a double-sided copper-clad laminate, mask exposure, development, and copper etching. The measurement results were evaluated according to the following criteria: A: -0.24 dB or greater; B: Less than -0.24 dB, -0.25 dB or greater; C: Less than -0.25 dB.

[0207]

[0208] As shown in Table 11, the films of Examples 103 to 126 contain an inorganic filler and a resin, and have a ratio (Do / Di) of 0.5 or more. Therefore, it was found that both a high dielectric constant and a low dielectric loss tangent could be achieved.

[0209] <<Examples 201 to 224>> Details of the materials used in producing the laminated films are as follows: Materials that are the same as those in Example 1A, etc. are omitted.

[0210] <Resin> P5: Styrene-ethylene-butylene-styrene block copolymer, product name "Tuftec M1913", manufactured by Asahi Kasei Chemicals Corporation

[0211] -Layer A, Layer B-Layer A and layer B were formed in the same manner as in Example 1A.

[0212] -Layer C- Layer C was formed on one surface of Layer A and Layer B in the same manner as in Example 9. As a result, copper foil M1, "Layer A and Layer B", and Layer C were formed in this order. Next, copper foil M1 was removed by etching with iron chloride. As a result, a film consisting of "Layer A and Layer B" and Layer C was formed.

[0213] -Laminated Film- The number of films each consisting of "Layer A and Layer B" and Layer C shown in Table 12 was stacked together, and hot pressed at 160°C and 4 MPa for 1 hour to obtain a laminated film.

[0214]

[0215] As shown in Table 12, the laminated films of Examples 201 to 224 contain inorganic fillers and resins, and are laminated with films having a ratio (Do / Di) of 0.5 or more. Therefore, it was found that both a high dielectric constant and a low dielectric loss tangent can be achieved.

[0216] The disclosures of Japanese Patent Application No. 2023-118688 filed on July 20, 2023, Japanese Patent Application No. 2023-187213 filed on October 31, 2023, Japanese Patent Application No. 2023-207955 filed on December 8, 2023, and Japanese Patent Application No. 2024-029091 filed on February 28, 2024 are incorporated herein by reference in their 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. It contains filler and resin, The filler is at least one selected from the group consisting of inorganic fillers and organic fillers. A film in which the ratio (Do / Di) of the number of fillers per unit area in the in-plane direction (Di) to the number of fillers per unit area in the thickness direction (Do) is 0.5 or greater.

2. The film according to claim 1, comprising the inorganic filler and the resin.

3. The film according to claim 2, wherein the relative dielectric constant of the inorganic filler is 1 to 20,000.

4. The film according to claim 2, wherein the relative dielectric constant of the inorganic filler is 6 to 20,000.

5. The film according to claim 2, wherein the inorganic filler comprises at least one selected from the group consisting of barium titanate, strontium titanate, calcium titanate, magnesium titanate, bismuth titanate, zirconium titanate, zinc titanate, titanium dioxide, magnesium oxide, alumina, tantalum pentoxide, and niobium pentoxide.

6. The film according to claim 1, comprising the organic filler and the resin.

7. The film according to claim 1, wherein the relative dielectric constant of the filler is 1 to 6.

8. The film according to any one of claims 1 to 7, wherein the average particle size of the filler is 0.01 μm to 10 μm.

9. The film according to any one of claims 1 to 7, wherein the content of the filler is 1% to 95% by volume relative to the total amount of the film.

10. The film according to any one of claims 1 to 7, wherein the resin comprises at least one selected from the group consisting of a thermoplastic resin, a thermoplastic elastomer, a thermosetting resin, or a semi-cured product of a photocurable resin, a cured product of the thermosetting resin, a cured product of the photocurable resin, a semi-cured product of a thermosetting elastomer, a semi-cured product of a photocurable elastomer, a cured product of the thermosetting elastomer, and a cured product of the photocurable elastomer.

11. The film according to claim 10, wherein the thermosetting resin or the photocurable resin is an epoxy resin, and further comprises an active ester compound as a curing agent.

12. The system comprises a plurality of layers A containing 50% or more of the filler, and a layer B containing the resin. The film according to any one of claims 1 to 7, wherein the plurality of layers A and the layer B are arranged in the same plane, and the plurality of layers A are arranged so as not to come into contact with each other.

13. It further contains a resin layer C, The film according to claim 12, wherein the resin layer C is in contact with the layer A and the layer B.

14. A film according to any one of claims 1 to 7, wherein the surface roughness is 5 μm or less.

15. A laminated film comprising films according to any one of claims 1 to 7, laminated so that they are in contact with each other.

16. A laminate comprising a metal layer or a metal pattern on at least one surface of a film according to any one of claims 1 to 7.

17. A printed circuit board comprising the laminate described in claim 16.

18. An antenna substrate comprising the laminate described in claim 16.

19. An antenna module that includes the antenna substrate described in claim 18 and performs at least one of transmitting and receiving radio waves with a frequency of 6 to 24 GHz.

20. An antenna module comprising the antenna substrate described in claim 18, which performs at least one of transmitting and receiving radio waves with a frequency of 0.5 to 5.9 GHz.

21. A pattern is provided on at least one surface of the film according to any one of claims 1 to 7, The aforementioned pattern is a metamaterial composed of at least one selected from the group consisting of conductive materials and materials that change from non-conductors to conductors.

22. An electromagnetic wave absorbing film comprising the metamaterial described in claim 21.