Syndiotactic polystyrene low transmission loss circuit board

Abstract

To provide a laminate which is excellent in peel strength and transmission loss that are suitable for electronic circuit board applications.SOLUTION: There is provided a laminate in which a resin layer (i), an adhesive layer (ii), and a metal layer (iii) are laminated in this order, wherein the resin layer (i) contains a styrenic polymer (A) having a syndiotactic structure, the resin layer (i) has a coefficient of linear expansion in a longitudinal direction (MD) and a transverse direction (TD) of 10 to 80 ppm / °C, a ratio of MD / TD satisfies a range of 0.6 to 1.4, peel strength between the resin layer (i) and the adhesive layer (ii) is 0.3 kN / m or more, and an absolute value of transmission at a frequency of 40 GHz of the laminate is 5.0 dB / 100 mm or less.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a laminate having an extremely low transmission loss and being suitable as an electronic circuit board, more specifically, to a laminate including a sheet or film using a syndiotactic polystyrene polymer having excellent dielectric properties and dimensional stability, an adhesive layer having excellent adhesion to the syndiotactic polystyrene polymer, and a metal layer having a low surface roughness. [Background technology]

[0002] In recent years, there has been active development of materials and applications for high-speed information communications such as 5G, and in order to improve information transmission speeds, there is a demand for plastic materials with low dielectric constants and dielectric loss tangents at high frequencies above 10 GHz. There is a similar need for printed wiring boards that use plastics with these excellent dielectric properties, and there is a demand for boards with even lower transmission loss.

[0003] Such circuit boards are often exposed to high temperature environments during use and manufacturing, and generally require high heat resistance and dimensional stability. Heat resistance here refers to the ability to withstand the heat treatment conditions (e.g. 260°C, 120 seconds) that occur during the soldering process in the manufacturing stage of circuit boards and electronic components.

[0004] For this reason, it is necessary to use plastics with excellent heat resistance that can withstand the soldering process, and fluororesin (PTFE) is used for printed wiring boards that require low transmission loss (Patent Document 1).

[0005] In addition, flexible printed wiring boards with excellent dielectric properties are being investigated by forming a wiring pattern made of a metal layer on a film of syndiotactic polystyrene (SPS) by electroless plating or vapor deposition (Patent Document 2). [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2003-171480 A [Patent Document 2] JP 2015-2334 A Summary of the Invention [Problem to be solved by the invention]

[0007] However, since the fluororesin such as PTFE described in Patent Document 1 has low adhesion to metal foil, it is difficult to laminate it with metal foil with low surface roughness. Therefore, it is necessary to use copper foil with a rough surface roughness, which deteriorates the transmission loss of the PTFE substrate in the high frequency range. In addition, in order to improve the adhesion, a special treatment such as irradiation with ultraviolet rays is required, which not only makes the manufacturing process complicated, but also leads to a decrease in productivity, resulting in an increase in the manufacturing cost of the substrate.

[0008] The printed wiring board made of SPS in Patent Document 2 has excellent dielectric properties, but is not able to withstand the ambient temperature (over 260°C) in the soldering process. In addition, because the metal layer is directly attached to the SPS substrate by plating or vapor deposition, stress is generated due to the difference in linear expansion coefficient between the metal layer and the substrate, which causes the wiring pattern of the metal layer to peel off at the interface with the substrate, making it less practical.

[0009] In view of the above circumstances, an object of the present invention is to provide a laminate having excellent peel strength and transmission loss between a resin layer and an adhesive layer. [Means for solving the problem]

[0010] The present inventors have conducted extensive research to solve the above problems and have arrived at the present invention. That is, the present invention relates to a laminate for an electronic circuit board as described in the following claims.

[0011] [1] A laminate comprising a resin layer (i), an adhesive layer (ii), and a metal layer (iii) laminated in this order, The resin layer (i) contains a styrene-based polymer (A) having a syndiotactic structure, the resin layer (i) has a linear expansion coefficient in a machine direction (MD) and a transverse direction (TD) of 10 to 80 ppm / °C, and a MD / TD ratio is in the range of 0.6 to 1.4; The peel strength between the resin layer (i) and the adhesive layer (ii) is 0.3 kN / m or more; The laminate has an absolute value of transmission loss of 5.0 dB / 100 mm or less at a frequency of 40 GHz. [2] The laminate according to [1], wherein the surface roughness Rz of the resin layer (i) is 0.1 μm or more and 6.0 μm or less. [3] The laminate according to [1] or [2], wherein the surface roughness Rz of the resin layer (i) is 0.1 μm or more and 3.0 μm or less. [4] The laminate according to any one of [1] to [3], wherein the adhesive layer (ii) contains a styrene-based elastomer and a curing agent. [5] The laminate according to any one of [1] to [4], wherein the surface roughness Rz of the metal layer (iii) is 0.1 μm or more and 7.0 μm or less. [6] The laminate according to any one of [1] to [5], wherein the resin layer (i) further contains a fibrous filler (C). [7] The laminate according to any one of [1] to [5], wherein the resin layer (i) further contains a non-fibrous filler (D). [8] The laminate according to any one of [1] to [5], wherein the resin layer (i) further contains a fibrous filler (C) and a non-fibrous filler (D). [9] The resin layer (i) further contains a fibrous filler (C) and a non-fibrous filler (D), The laminate according to any one of [1] to [5], comprising 1 to 50 parts by mass of the fibrous filler (C) per 100 parts by mass of the styrene-based polymer (A) having a syndiotactic structure.

[10] The laminate according to any one of [1] to [9], which is used for an electronic circuit board. Effect of the Invention

[0012] The laminate of the present invention is excellent in peel strength and transmission loss between the resin layer and the adhesive layer. In addition, the laminate of some embodiments of the present invention is also excellent in solder heat resistance. The laminate of the present invention can be suitably used for electronic circuit board applications. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] <Resin layer (i)> The resin layer (i) in the laminate of the present invention contains a styrene-based polymer (A) having a syndiotactic structure (hereinafter also referred to as "SPS", "syndiotactic polystyrene" or "(A) component"). The content of the (A) component in the resin layer (i) is preferably 40% by mass or more, more preferably 50% by mass or more, even more preferably 60% by mass or more, still more preferably 70% by mass or more, even more preferably 80% by mass or more, and particularly preferably 90% by mass or more, in order to improve the dielectric properties. The upper limit is not particularly limited, but is preferably less than 100% by mass, more preferably 99% by mass or less, and even more preferably 95% by mass or less, in order to improve the linear expansion coefficient and dimensional stability.

[0014] The resin layer (i) is preferably made of an unstretched sheet containing the component (A) or a film obtained by biaxially stretching the unstretched sheet. That is, the unstretched sheet or the biaxially stretched film is preferably laminated with the adhesive composition and the metal layer and subjected to a heat press treatment. Hereinafter, the unstretched sheet is also referred to simply as a "sheet" and the biaxially stretched film is also referred to simply as a "film", and these are collectively referred to as "sheet, etc."

[0015] The resin layer (i) may contain a fibrous filler (C) in addition to the styrene polymer (A) having a syndiotactic structure. When the fibrous filler (C) is contained, the content of the fibrous filler (C) is preferably 1 to 50 parts by mass per 100 parts by mass of the styrene polymer (A) having a syndiotactic structure. The resin layer (i) may contain a non-fibrous filler (D) in addition to the styrene polymer (A) having a syndiotactic structure. When the non-fibrous filler (D) is contained, the content of the non-fibrous filler (D) is preferably 1 to 60 parts by mass per 100 parts by mass of the styrene polymer (A) having a syndiotactic structure. It is also preferable that the resin layer (i) contains, in addition to the styrene-based polymer (A) having a syndiotactic structure, a fibrous filler (C) and a non-fibrous filler (D), and contains 1 to 50 parts by mass of the fibrous filler (C) per 100 parts by mass of the styrene-based polymer (A) having a syndiotactic structure.

[0016] <Styrene-based polymer (A) having a syndiotactic structure> In the present invention, the syndiotactic structure in the styrene-based polymer having a syndiotactic structure as component (A) is a stereochemical structure in which phenyl groups, which are side chains, are alternately positioned in opposite directions relative to the main chain formed from carbon-carbon bonds, and the tacticity is quantified by nuclear magnetic resonance (C-NMR) using a carbon isotope. Tacticity measured by C-NMR method can be expressed by the proportion of consecutive multiple structural units, for example, dyad when there are two, triad when there are three, and pentad when there are five. In the present invention, the styrene-based polymer having a syndiotactic structure usually refers to polystyrene, poly(alkylstyrene), poly(halogenated styrene), poly(halogenated alkylstyrene), poly(alkoxystyrene), poly(vinyl benzoate), hydrogenated polymers thereof, mixtures thereof, or copolymers having these as main components, having a syndiotacticity of preferably 75 mol % or more, more preferably 85 mol % or more in racemic dyad, or preferably 30 mol % or more, more preferably 50 mol % or more in racemic pentad.

[0017] In this case, examples of poly(alkylstyrene) include poly(methylstyrene), poly(ethylstyrene), poly(isopropylstyrene), poly(tert-butylstyrene), poly(phenylstyrene), poly(vinylnaphthalene), poly(vinylstyrene), etc., and examples of poly(halogenated styrene) include poly(chlorostyrene), poly(bromostyrene), poly(fluorostyrene), etc. In addition, examples of poly(halogenated alkylstyrene) include poly(chloromethylstyrene), etc., and examples of poly(alkoxystyrene) include poly(methoxystyrene), poly(ethoxystyrene), etc.

[0018] Among these, particularly preferred styrene-based polymers include polystyrene, poly(p-methylstyrene), poly(m-methylstyrene), poly(p-tert-butylstyrene), poly(p-chlorostyrene), poly(m-chlorostyrene), poly(p-fluorostyrene), hydrogenated polystyrene, and copolymers containing these structural units.

[0019] The styrene-based polymer (A) having a syndiotactic structure may be a copolymer of styrene having a syndiotactic structure and another monomer. The content of styrene having a syndiotactic structure in the component (A) is preferably 50% by mass or more. More preferably, it is 60% by mass or more, even more preferably, it is 70% by mass or more, even more preferably, it is 80% by mass or more, particularly preferably, it is 90% by mass or more, and most preferably, it is 100% by mass. When the content of styrene having a syndiotactic structure is 50% by mass or more, the dielectric properties, solder heat resistance, dimensional change rate, and linear expansion coefficient are excellent. In particular, since there is a possibility that the above-mentioned performance may be deteriorated, it is preferable to reduce the content of the unsaturated nitrile group-containing monomer, specifically, it is preferably 2% by mass or less, more preferably less than 2% by mass, further preferably 1% by mass or less, and particularly preferably 0% by mass.

[0020] The styrene polymer (A) having a syndiotactic structure may be used by mixing one type or two or more types of styrene polymers. There is no particular restriction on the composition ratio of the styrene copolymer, but the content of the substituted styrene unit is preferably in the range of 3 to 50 mol %. If the content is 3 mol % or more, modification is easy, and if it is 50 mol % or less, compatibility with other components can be maintained.

[0021] The molecular weight of the styrene-based polymer (A) having a syndiotactic structure is not particularly limited, but the weight average molecular weight is preferably 10,000 or more, more preferably 50,000 or more, and even more preferably 100,000 or more. Furthermore, there is no restriction on the width of the molecular weight distribution, and various types can be used. By making the weight average molecular weight 10,000 or more, the thermal properties and mechanical properties of the obtained composition or molded article are not reduced and good ones can be obtained. The upper limit is not particularly limited, but it is preferably 500,000 or less, more preferably 400,000 or less.

[0022] The styrene polymer (A) having such a syndiotactic structure can be produced, for example, by polymerizing a styrene monomer (a monomer corresponding to the above-mentioned styrene polymer) in an inert hydrocarbon solvent or in the absence of a solvent using a condensation product of a titanium compound, water and trialkylaluminum as a catalyst (JP-A-62-187708). Poly(halogenated alkylstyrene) can be obtained by the method described in JP-A-1-46912, and hydrogenated polymers thereof can be obtained by the method described in JP-A-1-178505.

[0023] The styrene-based polymer (A) having a syndiotactic structure preferably has a melt flow rate (MFR) measured at a temperature of 300° C. and a load of 1.2 kg of 1 to 60 g / 10 min, more preferably 2 to 40 g / 10 min, even more preferably 3 to 30 g / 10 min, and most preferably 4 to 20 g / 10 min. By setting the melt flow rate within the above range, a sheet or the like that is a precursor of the resin layer (i) having good physical properties can be obtained, and the film thickness can be made uniform.

[0024] The melting point of the styrene polymer (A) having a syndiotactic structure is preferably 250° C. or higher, more preferably 260° C. or higher, and preferably 300° C. or lower, more preferably 290° C. or lower. The glass transition temperature of the styrene polymer (A) having a syndiotactic structure is preferably 80° C. or higher, more preferably 90° C. or higher, and preferably 120° C. or lower, more preferably 110° C. or lower. By setting the melting point and glass transition temperature within the above ranges, the resin layer (i) has a low linear expansion coefficient and good dimensional stability.

[0025] Representative commercially available products of the styrene-based polymer (A) having a syndiotactic structure used in the present invention include, for example, XAREC (registered trademark) 142ZE, XAREC (registered trademark) 300ZC, XAREC (registered trademark) 130ZC, and XAREC (registered trademark) 90ZC manufactured by Idemitsu Kosan Co., Ltd. Among these resins, only one type may be used alone, or two or more types may be used in combination.

[0026] <Rubber-like elastic body (B)> The resin layer (i) preferably contains a rubber-like elastomer (B) (hereinafter also referred to as the (B) component). The rubber-like elastomer (B) is preferably incorporated because it imparts appropriate flexibility and improves mechanical properties when a sheet or the like is wound up, thereby suppressing cracking of the sheet or the like. The rubber-like elastomer (B) component may be a single polymer made of polyolefin, polystyrene, or polyacrylate, or a composition made of multiple copolymers containing these components. Specific examples of rubber-like elastomers include natural rubber, polybutadiene, polyisoprene, polyisobutylene, neoprene, polysulfide rubber, thiokol rubber, acrylic rubber, urethane rubber, silicone rubber, epichlorohydrin rubber, ethylene-propylene copolymer rubber (EPM), ethylene-propylene-diene copolymer rubber (EPDM), ethylene-α-olefin copolymer rubber, styrene-butadiene block copolymer (SBR), hydrogenated styrene-butadiene block copolymer (SEB, SEBC), styrene-butadiene-styrene block copolymer (SBS), hydrogenated styrene-butadiene-styrene block copolymer (SEBS), styrene-isoprene block copolymer (SIR), hydrogenated styrene-isoprene block copolymer (SEP ...BR), hydrogenated styrene-isoprene block copolymer (SEP), styrene-isoprene block copolymer (SBR), hydrogenated styrene-isoprene block copolymer (SEP), styrene-isoprene block copolymer (SBR), hydrogenated styrene-isoprene block copolymer (SEP), styrene-isoprene block copolymer (SBR), hydrogenated styrene-isoprene block copolymer (SEP), styrene-isoprene block copolymer (SBR), hydrogen Examples of the core-shell type particulate elastomer include styrene-styrene block copolymer (SIS), hydrogenated styrene-isoprene-styrene block copolymer (SEPS), butadiene-acrylonitrile-styrene-core-shell rubber (ABS), methyl methacrylate-butadiene-styrene-core-shell rubber (MBS), methyl methacrylate-butyl acrylate-styrene-core-shell rubber (MAS), octyl acrylate-butadiene-styrene-core-shell rubber (MABS), alkyl acrylate-butadiene-acrylonitrile-styrene-core-shell rubber (AABS), butadiene-styrene-core-shell rubber (SBR), and siloxane-containing core-shell rubbers such as methyl methacrylate-butyl acrylate-siloxane, or modified rubbers of these.

[0027] Among these, SEBS, SIR, SEP, SIS, SEPS, ethylene-α-olefin copolymer rubber, or modified rubbers thereof are particularly preferred. These rubbery elastomers can be used alone or in combination of two or more. From the viewpoint of the processing temperature when mixed with the styrene-based polymer (A) having a syndiotactic structure, a rubbery elastomer having high heat resistance is preferred, and mixing a rubbery elastomer in which the unsaturated bonds are selectively or completely hydrogenated suppresses the gas generated during hot pressing.

[0028] The rubber-like elastomer (B) preferably has a melt flow rate (MFR) of 0.1 to 40 g / 10 min, more preferably 1.0 to 20 g / 10 min, and even more preferably 1.5 to 14 g / 10 min, measured at a temperature of 230° C. and a load of 2.16 kg. By setting the melt flow rate within the above range, compatibility with the styrene-based polymer (A) having a syndiotactic structure is improved, and the thickness of the sheet or the like can be made uniform.

[0029] When the rubber-like elastomer (B) is contained, its content is preferably 1 to 40 parts by mass relative to 100 parts by mass of the styrene copolymer (A) having a syndiotactic structure. More preferably, it is 3 to 30 parts by mass, and even more preferably, it is 5 to 25 parts by mass. By making the content of the (B) component 1 part by mass or more, the flexibility of the sheet etc. is improved, and the winding property on a roll is improved. In addition, the workability of drilling holes in the subsequent process is improved. Furthermore, by making the content 40 parts by mass or less, the sheet etc. is prevented from becoming too soft, sticking to the roll is prevented, and the heat resistance required for a high-frequency circuit board can be maintained.

[0030] It is also preferable that the rubber-like elastic body (B) contains a styrene-based thermoplastic elastomer. When the rubber-like elastic body (B) is a styrene-based thermoplastic elastomer, the styrene content is preferably 5 to 60% by mass. More preferably, it is 8 to 50% by mass, further preferably, it is 10 to 40% by mass, and particularly preferably, it is 15 to 32% by mass. By making the styrene content 5% by mass or more, the compatibility between the (A) component and the (B) component is improved, and the mechanical properties are improved. In addition, by making the styrene content 60% by mass or less, the elastic modulus of the (B) component does not become too high, and the effect of stress relaxation is enhanced, so that the flexibility of the sheet is improved, and the polarity of the resin layer (i) can be suppressed, and an increase in the dielectric constant can be suppressed.

[0031] <Fibrous filler (C)> The resin layer (i) preferably contains a fibrous filler (C) (hereinafter also referred to as (C) component). The fibrous filler (C) is a fibrous filler that can improve the linear expansion coefficient and the effect of suppressing dimensional change in the direction parallel to the extrusion direction (MD) of the sheet or the like that is the precursor of the resin layer (i), and is a filler that is preferably contained in the resin layer (i) of the present invention, which may have a residual strain even though it is unstretched. In addition, by blending the (C) component, the solder heat resistance of the resin layer (i) and the laminate can be improved. The fibrous filler (C) can be inorganic or organic fiber. In the case of inorganic fibers, wollastonite (or whiskers) or glass fibers can be used, with glass fibers being particularly preferred in terms of dielectric properties. The content of the fibrous filler (C) is preferably 1 to 50 parts by mass per 100 parts by mass of the styrene-based polymer (A) having a syndiotactic structure in order to achieve a balance between the targeted linear expansion coefficient and dimensional stability, impact resistance, and mechanical properties. It is more preferably 3 to 40 parts by mass, and even more preferably 5 to 30 parts by mass.

[0032] The fibrous filler (C) can be in any shape, such as roving, surfacing mat, chopped strand mat, satin weave, lattice weave, plain weave, open-weave plain weave, twill weave, and net, and can be made from any type of glass, such as glass containing a large amount of alkali (C glass) or non-alkali glass (E glass).

[0033] More preferably, glass containing a large amount of boric acid (D glass) or glass with an adjusted balance between silicic acid and boric acid (NE glass) is used. D glass preferably contains SiO2 and B2O3, with the preferred range of SiO2 content being 65.0-80.0 mass%, and the preferred range of B2O3 content being 15.0-30.0 mass%. NE glass preferably contains SiO2 and B2O3, with the preferred range of SiO2 content being 45.0-65.0 mass%, and the preferred range of B2O3 content being 10.0-25.0 mass%.

[0034] The cross-sectional shape of the fibrous filler (C) may be a circular or noncircular glass fiber. The noncircular glass fiber may have a substantially elliptical, oval, or cocoon-shaped cross section perpendicular to the longitudinal direction of the fiber, and the flatness is preferably 1.5 to 8. The flatness is the ratio of the major axis to the minor axis when a rectangle with the minimum area circumscribing the cross section perpendicular to the longitudinal direction of the glass fiber is assumed, and the length of the long side of the rectangle is the major axis and the length of the short side is the minor axis. The thickness of the glass fiber is not particularly limited, but the minor axis is about 1 to 20 μm and the major axis is about 2 to 100 μm. The diameter of the glass fiber with a circular cross section is preferably 1 to 50 μm, more preferably 2 to 20 μm, and even more preferably 3 to 15 μm.

[0035] The D50 average fiber length of the fibrous filler (C) is preferably 40 μm to 4000 μm, more preferably 40 μm to 3200 μm, even more preferably 45 μm to 2000 μm, and most preferably 50 μm to 500 μm. If the D50 average fiber length is 40 μm or more, the surface area of ​​the fibrous filler (C) is sufficiently large, the adhesion of the interface between the matrix resin (A) component and the (C) component is improved, and the physical properties of the sheet, etc. are improved. In addition, by making it 4000 μm or less, the rigidity of the sheet, etc. during film formation can be prevented from becoming too high, and the occurrence of cracks observed during winding can be suppressed. Furthermore, the occurrence of aggregates in the sheet, etc. can be suppressed.

[0036] The fibrous filler (C) may or may not be surface-treated. When the fibrous filler (C) is surface-treated, examples of the coupling agent used for the surface treatment include a silane coupling agent and a titanium coupling agent. Among them, it is particularly preferable to perform the surface treatment with a silane coupling agent from the viewpoint of compatibility with the (A) component. Specific examples of the silane coupling agent include triethoxysilane, vinyltris(β-methoxyethoxy)silane, γ-methacryloxypropyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, β-(1,1-epoxycyclohexyl)ethyltrimethoxysilane, N-β-(aminoethyl)-γ-aminopropyltrimethoxysilane, N-β-(aminoethyl)-γ-aminopropylmethyldimethoxysilane, γ-aminopropyltriethoxysilane, N-phenyl-γ-aminopropyltrimethoxysilane, γ-mercapto ... Examples of the silane include silane, γ-chloropropyltrimethoxysilane, γ-aminopropyltrimethoxysilane, γ-aminopropyl-tris(2-methoxyethoxy)silane, N-methyl-γ-aminopropyltrimethoxysilane, N-vinylbenzyl-γ-aminopropyltriethoxysilane, 3-ureidopropyltrimethoxysilane, 3-4,5-dihydroimidazolepropyltriethoxysilane, hexamethyldisilazane, N,N-bis(trimethylsilyl)urea, 3-triethoxysilyl-N-(1,3-dimethylbutylidene)propylamine, etc. Among these, aminosilanes and epoxysilanes such as γ-aminopropyltrimethoxysilane, N-β-(aminoethyl)-γ-aminopropyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, and β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane are preferred.

[0037] Specific examples of titanium-based coupling agents include isopropyl triisostearoyl titanate, isopropyl tridodecylbenzenesulfonyl titanate, isopropyl tris(dioctyl pyrophosphate) titanate, tetraisopropyl bis(dioctyl phosphite) titanate, tetraoctyl bis(ditridecyl phosphite) titanate, tetra(1,1-diallyloxymethyl-1-butyl)bis(ditridecyl)phosphite titanate, and bis(dioctyl pyrophosphate)oxyacetate. Titanate, bis(dioctyl pyrophosphate)ethylene titanate, isopropyl trioctanoyl titanate, isopropyl dimethacryl isostearoyl titanate, isopropyl isostearoyl diacryl titanate, isopropyl tri(dioctyl phosphate) titanate, isopropyl tricumyl phenyl titanate, isopropyl tri(N-amidoethyl, aminoethyl) titanate, dicumyl phenyloxy acetate titanate, diisostearoyl ethylene titanate, etc. Among these, isopropyl tri(N-amidoethyl, aminoethyl) titanate is preferred.

[0038] The surface treatment method of the fibrous filler (C) using the coupling agent is not particularly limited. For example, the surface treatment can be carried out by a method appropriate for the shape of the fibrous filler (C), such as a sizing treatment in which an organic solvent solution or suspension of the coupling agent is applied to the fibrous filler (C) as a sizing agent, a dry mixing treatment using a Henschel mixer, a super mixer, a Loedige mixer, a V-type blender, or the like, a spray method, an integral blend method, or a dry concentrate method. Among these, it is preferable to perform the surface treatment by a sizing treatment, a dry mixing treatment, or a spray method. For example, a glass film-forming substance can be used in combination with the above coupling agent. The film-forming substance is not particularly limited, and examples thereof include polyester-based, urethane-based, epoxy-based, acrylic-based, vinyl acetate-based, polyether-based, and other polymers.

[0039] A modified polymer may be used as a compatibilizer for the fibrous filler (C). The compatibilizer is added for the purpose of improving the interfacial strength between the syndiotactic polystyrene polymer (A) and the fibrous filler (C) and non-fibrous filler (D).

[0040] Specific examples of the compatibilizer include modified polyphenylene ether polymers such as styrene-maleic anhydride copolymer (SMA), styrene-glycidyl methacrylate copolymer, terminal carboxylic acid modified polystyrene, terminal epoxy modified polystyrene, terminal oxazoline modified polystyrene, terminal amine modified polystyrene, sulfonated polystyrene, styrene-based ionomer, styrene-methyl methacrylate graft polymer, (styrene-glycidyl methacrylate)-methyl methacrylate graft copolymer, acid modified acrylic-styrene graft polymer, (styrene-glycidyl methacrylate)-styrene graft polymer, polybutylene terephthalate-polystyrene graft polymer, polyphenylene ether, (styrene-maleic anhydride)-polyphenylene ether graft polymer, maleic anhydride modified polyphenylene ether, fumaric acid modified polyphenylene ether, glycidyl methacrylate modified polyphenylene ether, and amine modified polyphenylene ether. Among these, unmodified or modified polyphenylene ether is preferred, and maleic anhydride-modified polyphenylene ether and fumaric acid-modified polyphenylene ether are more preferred.

[0041] <Non-fibrous filler (D)> The resin layer (i) preferably contains a non-fibrous filler (D) (hereinafter also referred to as (D) component). The non-fibrous filler (D) is a non-fibrous filler that is expected to suppress the linear expansion coefficient and dimensional change in the direction parallel (MD) and perpendicular (TD) to the extrusion direction of the sheet or the like, which is the precursor of the resin layer (i). As the non-fibrous filler (D), a filler having a known shape such as a spherical, granular, or plate-like shape can be used. Either an inorganic or organic filler may be used, but inorganic spherical, granular, or plate-like fillers are preferred, such as talc, carbon black, graphite, titanium dioxide, silica, mica, calcium carbonate, calcium sulfate, barium carbonate, magnesium carbonate, magnesium sulfate, barium sulfate, oxysulfate, tin oxide, alumina, kaolin, silicon carbide, metal powder, glass powder, glass flakes, glass beads, etc.

[0042] Among these inorganic fillers, silica is particularly preferred from the viewpoints of productivity, cost, and the dielectric properties of the filler itself, and amorphous silica or fused silica is more preferred. Amorphous silica has a lower hardness than crystalline silica, and can suppress wear of machines and screws.

[0043] Fused silica is made by melting the raw material in a flame and then rapidly solidifying the volatilized gas. The result is that the material is spherical due to surface tension, with few sharp edges and the filler itself is not prone to crumbling, making it easy to form a stable shape.

[0044] The shape of the silica is preferably granular or spherical, and more preferably spherical. The granular or spherical shape of the silica makes it easy to mix when added to a molten resin. In addition, since the silica is stable regardless of the direction of force, the mechanical properties of the resin layer (i) are less likely to decrease, and the silica is less likely to fall off during film formation such as a sheet after being broken.

[0045] The D50 average particle size of the non-fibrous filler (D) is preferably 0.1 to 45 μm. More preferably, it is 0.2 to 30 μm, even more preferably 0.3 to 20 μm, and even more preferably 0.5 to 10 μm. By having a D50 average particle size of 0.1 μm or more, aggregation of the (D) components is suppressed, they do not become foreign matter in the resin layer (i), and the mechanical properties are not deteriorated. In addition, by having a D50 average particle size of 45 μm or less, the interval between the (D) components does not become too narrow, and the propagation of cracks at the interface when stress is generated can be suppressed. In addition, heat resistance can be maintained in the soldering process.

[0046] The content of the non-fibrous filler (D) is preferably 1 to 60 parts by mass relative to 100 parts by mass of the polystyrene-based polymer (A) having a syndiotactic structure. It is more preferably 3 to 50 parts by mass, and even more preferably 5 to 40 parts by mass. If it is 1 part by mass or more, the effect of the (D) component can be exhibited. Furthermore, by making it 60 parts by mass or less, the smoothness of the sheet or the like is improved, and it is easy to control the film thickness, and it is possible to suppress the aggregation of the (D) components in the resin layer (i) and suppress the deterioration of the mechanical properties.

[0047] The above does not apply in the case of hollow amorphous silica and fused silica. By using hollow silica, it is expected that the dielectric constant can be further reduced. When hollow silica is used, the film thickness is preferably in the range of 0.5 to 2.0 μm, more preferably 0.5 to 1.5 μm, and even more preferably 0.5 to 1.2 μm. If the film thickness is too thin, the silica may break during screw mixing in the twin-screw kneader, and the hollow shape may not be maintained. If the film thickness is too thick, the volume fraction of the hollow portion decreases, and the effect of reducing the dielectric constant may not be achieved. The D50 average particle size of the hollow silica is preferably in the range of 3 to 45 μm. If the particle size is less than 3 μm, the effect of reducing the dielectric constant cannot be expected, and if the particle size exceeds 45 μm, the mechanical properties of the sheet, etc., decrease.

[0048] The non-fibrous filler (D) may be either surface-treated or untreated. The surface treatment agent is not limited as long as it is a known agent, but by subjecting the filler to hydrophobic treatment with a silane- or titanate-based coupling agent, the filler can be dispersed well in the styrene polymer (A) having a syndiotactic structure, and the generation of aggregates in the resin layer (i) can be suppressed.

[0049] As the organic spherical, granular or plate-like filler, the polymer to be used is not particularly limited, but in consideration of the processing temperature of the styrene-based resin (A) having a syndiotactic structure, if it is a crystalline resin, it is preferable that the melting point is more than 280°C, more preferably more than 300°C. Also, if it is an amorphous resin, it is preferable that the glass transition temperature is more than 150°C, more preferably more than 180°C. By setting the melting point and glass transition temperature within the above ranges, the shape of the filler can be maintained during processing into a sheet or the like, and the effect of suppressing the linear expansion coefficient of the resin layer (i) can be expressed.

[0050] <Antioxidants (E)> From the viewpoint of processability, the resin layer (i) of the present invention may contain the following antioxidant (E) (hereinafter, also referred to as component (E)). The antioxidant (E) in the present invention may be either a primary antioxidant that prevents oxidation by capturing generated radicals, or a secondary antioxidant that prevents oxidation by decomposing generated peroxides. Examples of the primary antioxidant include phenol-based antioxidants and amine-based antioxidants, and examples of the secondary antioxidant include phosphorus-based antioxidants and sulfur-based antioxidants. By blending these antioxidants alone or in combination, it is possible to suppress the decrease in molecular weight of component (A) or (B) during the production of the SPS resin composition, and to suppress the generation of gas derived from component (A) or (B) during the hot pressing step in the production of the resin layer (i).

[0051] Specific examples of the phenol-based antioxidant include monophenol-based antioxidants such as 2,6-di-t-butyl-4-methylphenol, 2,6-di-t-butyl-4-ethylphenol, 2-t-butyl-4-methoxyphenol, 3-t-butyl-4-methoxyphenol, 2,6-di-t-butyl-4-[4,6-bis(octylthio)-1,3,5-triazin-2-ylamino]phenol, and n-octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate. Further examples include bisphenol-based antioxidants such as 2,2'-methylenebis(4-methyl-6-t-butylphenol), 2,2'-methylenebis(4-ethyl-6-t-butylphenol), 4,4'-thiobis(3-methyl-6-t-butylphenol), 4,4'-butylidenebis(3-methyl-6-t-butylphenol), N,N'-bis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionyl]hydrazine, N,N'-hexane-1,6-diylbis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionamide], and 3,9-bis[1,1-dimethyl-2-[β-(3-t-butyl-4-hydroxy-5-methylphenyl)propionyloxy]ethyl]-2,4,8,10-tetraoxaspiro[5.5]undecane. Further examples include polymeric phenolic antioxidants such as 1,1,3-tris(2-methyl-4-hydroxy-5-t-butylphenyl)butane, 1,3,5-trimethyl-2,4,6-tris(3,5-di-t-butyl-4-hydroxybenzyl)benzene, pentaerythritol tetrakis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate], bis[3,3'-bis-(4'-hydroxy-3'-t-butylphenyl)butyric acid]glycol ester, 1,3,5-tris(3',5'-di-t-butyl-4'-hydroxybenzyl)-sec-triazine-2,4,6-(1H,3H,5H)trione, and d-α-tocophenol.

[0052] Specific examples of amine-based antioxidants include alkyl-substituted diphenylamines.

[0053] Specific examples of phosphorus-based antioxidants include triphenyl phosphite, diphenyl isodecyl phosphite, phenyl diisodecyl phosphite, 4,4'-butylidene-bis(3-methyl-6-t-butylphenyl ditridecyl) phosphite, octadecyl phosphite, tris(nonylphenyl) phosphite, diisodecyl pentaerythritol diphosphite, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, 10-(3,5-di-t-butyl-4-hydroxybenzyl)-9,10- Examples of such phosphatides include dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, 10-decyloxy-9,10-dihydro-9-oxa-10-phosphaphenanthrene, tris(2,4-di-t-butylphenyl)phosphite, cyclic neopentanetetraylbis(2,4-di-t-butylphenyl)phosphite, cyclic neopentanetetraylbis(2,6-di-t-butyl-4-methylphenyl)phosphite, and 2,2'-methylenebis(4,6-di-t-butylphenyl)octylphosphite.

[0054] Specific examples of sulfur-based antioxidants include dilauryl-3,3'-thiodipropionate, dimyristyl-3,3'-thiodipropionate, distearyl-3,3'-thiodipropionate, pentaerythritol tetrakis(3-laurylthiopropionate), 2-mercaptobenzimidazole, and the like.

[0055] The antioxidant is preferably a primary antioxidant from the viewpoint of suppressing the heat resistance of the resin layer (i) and thermal degradation during processing, and among them, a phenol-based antioxidant is particularly preferred. The antioxidant preferably has a thermal decomposition temperature of 250°C or higher. If the thermal decomposition temperature is high, the effect of improving the dielectric breakdown voltage at high temperatures will be high. If the thermal decomposition temperature is too low, the antioxidant itself will thermally decompose during melt extrusion, which tends to cause problems such as contaminating the process and coloring the polymer yellow, which is not preferable. From this viewpoint, the thermal decomposition temperature of the antioxidant is more preferably 280°C or higher, even more preferably 300°C or higher, and particularly preferably 320°C or higher. The antioxidant in the present invention is preferably less susceptible to thermal decomposition, and the thermal decomposition temperature is preferably high, but in reality, the upper limit is about 500°C or lower.

[0056] The melting point of the antioxidant is preferably 90°C or higher. If the melting point is too low, the antioxidant melts faster than the polymer during melt extrusion, and the polymer tends to slip at the screw feed portion of the extruder. This causes problems such as unstable polymer supply and poor thickness unevenness of the sheet, etc. From this viewpoint, the melting point of the antioxidant is more preferably 120°C or higher, even more preferably 150°C or higher, and particularly preferably 200°C or higher. On the other hand, if the melting point of the antioxidant is too high, the antioxidant tends to be difficult to melt during melt extrusion, and dispersion in the polymer tends to be poor. This causes problems such as the effect of adding the antioxidant only being expressed locally. From this viewpoint, the melting point of the antioxidant is preferably 300°C or lower, more preferably 250°C or lower, even more preferably 220°C or lower, and particularly preferably 170°C or lower.

[0057] As the antioxidant, commercially available products can be used as they are. Examples of commercially available products include pentaerythritol tetrakis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate] (manufactured by Ciba Specialty Chemicals, Inc., trade name IRGANOX1010), N,N'-bis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionyl]hydrazine (manufactured by Ciba Specialty Chemicals, Inc., trade name IRGANOX1024), and N,N'-hexane-1,6-diylbis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionamide] (manufactured by Ciba Specialty Chemicals, Inc., trade name IRGANOX1098).

[0058] The content of the antioxidant is preferably 0.1% by mass or more and 8% by mass or less based on the mass of the polystyrene resin composition. By containing the antioxidant in the above-mentioned numerical range, the heat resistance and heat deterioration resistance properties of the sheet can be improved. If the content of the antioxidant is too small, the effect of adding the antioxidant is insufficient, and the effect of improving the dielectric breakdown voltage tends to be low. From this viewpoint, the content of the antioxidant is more preferably 0.2% by mass or more, even more preferably 0.3% by mass or more, and particularly preferably 0.5% by mass or more. On the other hand, if the content is too high, the antioxidant tends to be easily aggregated in the resin layer (i), and the defects caused by the antioxidant tend to increase, and the mechanical properties of the resin layer (i) are reduced due to such defects. From this viewpoint, the content of the antioxidant is more preferably 6% by mass or less, even more preferably 4% by mass or less, and particularly preferably 2% by mass or less.

[0059] The antioxidant may be used alone or in combination of two or more. When two or more types are used in combination, two or more primary antioxidants may be used, two or more secondary antioxidants may be used, or one or more primary antioxidants and one or more secondary antioxidants may be used in combination. For example, by using two antioxidants, a primary antioxidant and a secondary antioxidant, in combination, it is expected that both primary oxidation and secondary oxidation can be prevented. In the present invention, the mode in which a primary antioxidant is used alone or the mode in which two or more primary antioxidants are used are preferred from the viewpoint of being able to enhance the effect of suppressing thermal deterioration during processing, and the mode in which a phenol-based antioxidant is used alone or the mode in which two or more phenol-based antioxidants are used are particularly preferred.

[0060] The resin layer (i) of the present invention may contain flame retardants, release agents, lubricants, viscosity reducing agents, hardeners, etc. other than those mentioned above. The flame retardants are not particularly limited, but halogen-based ones containing bromine, and organic or inorganic phosphate-phosphate ester-phosphorus copolymers, etc., can be suitably used. The flame retardants used may be liquid or solid, but from the viewpoint of long-term stability, it is preferable to use those that are solid at room temperature.

[0061] <Polystyrene-based resin composition> The polystyrene resin composition is a composition that contains the above-mentioned component (A) as a main component, and optionally contains the components (C) and (D) in predetermined amounts, and further optionally contains the component (B) or (E). The polystyrene resin composition can be used to manufacture the sheet of the present invention. The polystyrene resin composition is preferably prepared by blending the above-mentioned components in predetermined amounts, kneading, and pelletizing them.

[0062] <Sheet / Film> The sheet or film of the present invention is an unstretched sheet containing the component (A) or a film obtained by biaxially stretching the unstretched sheet, preferably an unstretched sheet containing the polystyrene-based resin composition or a film obtained by biaxially stretching the unstretched sheet.

[0063] The unstretched sheet is not only not completely stretched, but may have some residual strain. Specifically, the stretch ratio is preferably 1.3 or less in both the direction parallel to the extrusion direction of the sheet (machine direction, MD) and the direction perpendicular to the extrusion direction of the sheet (transverse direction, TD).

[0064] The roll temperature during the production of a sheet or the like is preferably 30 to 100°C, more preferably 40 to 95°C, and even more preferably 60 to 90°C. By setting the roll temperature within the above range, the roll winding properties and the surface roughness Rz of the sheet can be made uniform and small. If the roll temperature is 30°C or lower, condensation may occur on the roll surface, and water droplets may adhere to the sheet and be transferred as surface unevenness. If the roll temperature exceeds 100°C, the molten resin may stick to the roll, making it difficult to stretch and wind the sheet.

[0065] The pressure of the touch roll when producing a sheet or the like is preferably a linear pressure of 50 to 2000 N / cm. By using this pressure, the thickness of the sheet can be made uniform, and the surface roughness Rz can be made uniform and small. If the pressure is less than 50 N / cm, the thickness of the sheet may become uneven, and the surface roughness Rz may become non-uniform and large. If the pressure exceeds 2000 N / cm, the thickness of the sheet may become non-uniform, residual stress may easily remain, and the winding property of the sheet may be deteriorated.

[0066] When producing a sheet or the like, it is preferable to apply pressure so that the sheet has a thickness of 50 to 2000 μm. If the thickness is less than 50 μm, it is difficult to apply pressure uniformly, which may result in a decrease in mechanical properties and non-uniform surface roughness Rz. If the thickness exceeds 2000 μm, it is difficult to apply sufficient pressure, which may result in non-uniform sheet thickness and surface roughness Rz.

[0067] The material of the two rolls used in producing a sheet or the like is not particularly limited and may be rubber, a metal roll, resin, or the like. From the viewpoint of reducing the surface roughness Rz and applying a pressure evenly, it is preferable that the rolls are made of metal.

[0068] When performing biaxial stretching, the stretching ratio, stretching temperature and stretching speed are not particularly limited as long as the object of the present invention can be achieved, but it is preferable to set them in the following ranges. By performing stretching, the heat-resistant dimensional stability of the sheet and the resin layer (i) is improved. There are uniaxial stretching, sequential biaxial stretching and simultaneous biaxial stretching methods, but it is preferable to perform simultaneous biaxial stretching or sequential biaxial stretching. More preferably, it is the simultaneous biaxial stretching method. If sequential biaxial stretching is performed instead of simultaneous biaxial stretching, the reduction in the thermal expansion coefficient in the direction in which the stretching was performed first becomes small and the heat-resistant dimensional stability may decrease, so this tendency becomes stronger unless the stretching speed is slowed. If uniaxial stretching is performed instead of biaxial stretching, the linear expansion coefficient in the direction that is not stretched does not decrease, and the heat-resistant dimensional stability may decrease.

[0069] The stretching ratio is within a range where breakage does not occur of 2.0 times or more in both the MD and TD directions, and is particularly preferably 2.0 to 5.0 times, and more preferably 2.3 to 4.0 times. It is preferable that the stretching ratios in the MD and TD directions are similar. Specifically, when the stretching ratio in the MD direction is PMD and the stretching ratio in the TD direction is PTD, "PTD-PMD" is preferably -0.6 to +0.6, and more preferably -0.3 to +0.3. The stretching ratio in the MD direction is based on the MD length immediately before stretching. The stretching ratio in the TD direction is based on the TD length immediately before stretching.

[0070] By adjusting the stretch ratio within the above range, the difference in linear expansion coefficient between MD and TD is reduced, and the decrease in linear expansion coefficient can be controlled. For example, increasing the stretch ratio in a given direction increases the decrease in linear expansion coefficient in that direction.

[0071] When the glass transition temperature of the SPS resin constituting the sheet or the like is defined as TgP (°C), the stretching temperature is preferably at least TgP and not more than TgP + 30°C, and from the viewpoint of further improving heat-resistant dimensional stability, tensile strength and tensile elongation, is more preferably at least TgP°C and not more than TgP + 25°C. If the stretching temperature is too low, stress concentration is likely to occur, making the sheet more likely to break, whereas if the stretching temperature is too high, crystallization of the sheet will be insufficient, the degree of reduction in the thermal expansion coefficient will be small, and dimensional stability during heat resistance may decrease.

[0072] The stretching temperature is the temperature of the sheet or the like when stretching is performed. When the SPS resin is composed of two or more polymers, the TgP of the SPS resin can be confirmed from the endothermic peak (relaxation of the amorphous part) observed by differential scanning calorimetry (DSC).

[0073] By adjusting the stretching temperature within the above range, the degree of decrease in the linear expansion coefficient can be controlled. For example, when the stretching temperature is lowered, the degree of decrease in the linear expansion coefficient increases.

[0074] The stretching speed is 50 to 10,000% / min in both the MD and TD directions, preferably 100 to 5,000% / min, and more preferably 100 to 3,000% / min. The stretching speed is a value calculated by {(dimension after stretching / dimension before stretching)-1}×100(%) / stretching time.

[0075] By adjusting the stretching speed within the above range, it is possible to control the degree of decrease in the linear expansion coefficient. For example, increasing the stretching speed increases the degree of decrease in the linear expansion coefficient.

[0076] The heat treatment is a treatment for fixing the orientation of polymer molecules by holding the stretched film at a temperature equal to or higher than the stretching temperature. The heat treatment temperature is TgP+70°C or higher and TmP or lower, where TgP (°C) is the glass transition temperature of the polymer component constituting the film, and TmP (°C) is the melting point. From the viewpoint of heat-resistant dimensional stability and thermal shrinkage, the heat treatment temperature is preferably TgP+75°C or higher and TmP-20°C or lower. The heat treatment temperature is the atmospheric temperature at which the film is held. When the polymer component is composed of two or more kinds of polymers, the TmP of the polymer component is the sum of the melting points of the respective polymers multiplied by the content ratio of the respective polymers.

[0077] The absolute value of the heat shrinkage can be controlled by adjusting the heat treatment temperature within the above range. For example, increasing the heat treatment temperature decreases the absolute value of the heat shrinkage.

[0078] The heat treatment may be a tension type heat treatment in which the heat treatment is performed while maintaining the tension during the biaxial stretching treatment, a relaxation type heat treatment in which the heat treatment is performed while relaxing the tension at the same time as the biaxial stretching treatment, or a combined heat treatment in which the heat treatment is performed while maintaining the tension (first heat treatment) and then the heat treatment is performed while relaxing the tension (second heat treatment). A relaxation type heat treatment is preferably performed. When the heat treatment is performed by any of the above methods, the heat treatment temperature is set within the above range.

[0079] When the heat treatment is performed by the above-mentioned relaxation method or combined method, from the viewpoints of reducing the absolute value of the thermal shrinkage rate, heat-resistant dimensional stability, and flatness of the film, the relaxation ratio is preferably 0.8 to 1.00 times in both the MD and TD directions, more preferably 0.85 to 1.00 times, and most preferably 0.90 to 0.98 times. It is preferable that the relaxation ratios in the MD and TD directions are similar. Specifically, when the relaxation ratio in the MD direction is QMD and the relaxation ratio in the TD direction is QTD, "QTD-QMD" is preferably -0.1 to +0.1, more preferably -0.05 to +0.05, and most preferably -0.02 to +0.02. The relaxation ratio in the MD direction is based on the MD length immediately after stretching. The relaxation ratio in the TD direction is based on the TD length immediately after stretching.

[0080] The absolute value of the heat shrinkage can be controlled by adjusting the relaxation ratio within the above range. For example, when the relaxation ratio in a certain direction is reduced, the decrease in the absolute value of the heat shrinkage in that direction becomes large.

[0081] The surface roughness (Rz) of the resin layer (i) of the present invention is preferably 0.1 μm or more and 6.0 μm or less. Since the adhesion to the adhesive layer (ii) is good, it is more preferably 0.15 μm or more, and even more preferably 0.2 μm or more. In addition, since the local thickness unevenness with the adhesive layer (ii) is small and the occurrence of wrinkles in the metal layer (iii) is suppressed, it is more preferably 5.0 μm or less, even more preferably 3.0 μm or less, even more preferably 2.5 μm or less, and particularly preferably 2.0 μm or less.

[0082] In order to set the surface roughness (Rz) of the resin layer (i) of the present invention within the above range, the surface roughness (Rz) of the sheet or film is preferably 0.1 μm or more and 6.0 μm or less. More preferably, it is 0.15 μm or more and 5.0 μm or less, and even more preferably, it is 0.2 μm or more and 3.0 μm or less. In a preferred embodiment, the resin layer (i) is made of a sheet or the like, and therefore, it is considered that the surface roughness (Rz) of the sheet or the like affects the surface roughness (Rz) of the resin layer (i).

[0083] The relative dielectric constant (ε c ) is preferably 3 or less at a temperature of 23°C, a relative humidity of 50%, and a frequency of 10 GHz. More preferably, it is 2.8 or less, and even more preferably, it is 2.7 or less. When the relative dielectric constant is 3 or less, the signal transmission speed is fast and the dielectric loss can be reduced. There is no particular restriction on the lower limit, but industrially, it may be 1.0 or more, and it may be 2.0 or more.

[0084] The dielectric loss tangent (tan δ) of the resin layer (i) of the present invention is preferably 0.002 or less at a temperature of 23° C., a relative humidity of 50%, and a frequency of 10 GHz. It is more preferably 0.0015 or less, and even more preferably 0.001 or less. When the dielectric loss tangent is 0.002 or less, the dielectric loss is suppressed, and the performance as a circuit board at high frequencies is good. The lower limit is not particularly limited, but it may be 0.0001 or more, or may be 0.0002 or more.

[0085] When the resin layer (i) has a relative dielectric constant and a dielectric loss tangent within the above ranges, when the laminate is used for an electronic circuit board, the transmission loss of an electric signal flowing through the dielectric part of the laminate is small, and excellent properties can be exhibited.

[0086] The linear expansion coefficient of the resin layer (i) in the machine direction (MD) and the transverse direction (TD) must be 10 to 80 ppm / °C, respectively. It is preferably 15 ppm / °C or more, more preferably 20 ppm / °C or more, and preferably 75 ppm / °C or less, more preferably 70 ppm / °C or less. In addition, the MD / TD ratio must be 0.6 to 1.4. It is preferably 0.65 or more, more preferably 0.7 or more, and preferably 1.35 or less, more preferably 1.3 or less. The linear expansion coefficient of the resin layer (i) may be measured by taking out only the resin layer (i) from the laminate. The method of taking out the resin layer (i) is not particularly limited, and for example, the metal layer (iii) may be removed by etching, and the adhesive layer (ii) may be dissolved and removed with a solvent or scraped off. In addition, when the longitudinal direction (MD) and transverse direction (TD) of the resin layer (i) taken out from the laminate are unknown, the linear expansion coefficients of one direction 1 and the direction 2 perpendicular thereto are measured, and both MD / TD when the direction 1 is MD and the direction 2 is TD, and MD / TD when the direction 1 is TD and the direction 2 is MD are obtained, and both are within the above range.

[0087] In order to set the linear expansion coefficient of the resin layer (i) within the above range, the linear expansion coefficient in the machine direction (MD) and the transverse direction (TD) of the heat-treated sheet or film is preferably 10 to 80 ppm / ° C., more preferably 15 to 75 ppm / ° C., and even more preferably 20 to 70 ppm / ° C. The MD / TD ratio is preferably 0.6 to 1.4, more preferably 0.65 to 1.35, and even more preferably 0.7 to 1.3.

[0088] By making the linear expansion coefficient value within the above range, the bonding property between the adhesive layer (ii) and the metal layer (iii) is improved in the hot press process for manufacturing the laminate, and wrinkles occurring in the laminate or the metal layer can be suppressed. In addition, by making the MD / TD ratio within the above range, warping of the laminate and wrinkles on the surface of the laminate or the metal layer can be suppressed.

[0089] The resin layer (i) and the heat-treated sheet of the present invention preferably have a dimensional change rate of less than 1.0% in each of the machine direction (MD) and the transverse direction (TD) when heat-treated at 150°C for 30 minutes, preferably 0.6% or less, more preferably 0.4% or less, even more preferably 0.3% or less, and most preferably 0.2% or less.

[0090] By having the thermal shrinkage rate fall within the above range, the bonding property between the adhesive layer (ii) and the metal layer (iii) is improved during the hot pressing step in producing the laminate, and wrinkles occurring in the laminate or the metal layer (iii) can be suppressed.

[0091] The thickness of the resin layer (i) of the present invention is preferably 10 μm to 2000 μm, more preferably 15 μm to 1000 μm, further preferably 20 μm to 500 μm, and most preferably 25 μm to 300 μm. When the thickness is 10 μm or more, the resin layer (i) is less likely to crack. Also, when the thickness is 2000 μm or less, the occurrence of partial shrinkage (sink marks) is suppressed, and thickness unevenness does not occur.

[0092] To set the thickness of the resin layer (i) within the above range, the thickness of the sheet or the like is preferably 10 μm to 2000 μm, more preferably 15 μm to 1000 μm, further preferably 20 μm to 500 μm, and most preferably 25 μm to 300 μm.

[0093] <Adhesive layer (ii)> The adhesive layer (ii) in the laminate of the present invention is preferably a cured product of an adhesive composition containing an acid-modified styrene-based elastomer (a) and a curing agent (b), and further contains an oligophenylene ether (c) and an acid-modified polyolefin (d) as necessary. The content of the acid-modified styrene-based elastomer (a) is preferably 50 parts by mass or more per 100 parts by mass of the solid content of the adhesive composition, and the content of the curing agent (b) is preferably 1 to 20 parts by mass per 100 parts by mass of the acid-modified styrene-based elastomer (a).

[0094] <Acid-modified styrene-based elastomer (a)> The acid-modified styrene-based elastomer (a) (hereinafter also referred to as component (a)) is one of the main components of the adhesive composition, and is a component that imparts electrical properties in addition to adhesiveness and flexibility of the cured product. The acid-modified styrene-based elastomer (a) is preferably a copolymer mainly composed of block and random structures of a conjugated diene compound and an aromatic vinyl compound, and a hydrogenated product thereof modified with an unsaturated carboxylic acid. Examples of the aromatic vinyl compound include styrene, t-butylstyrene, α-methylstyrene, p-methylstyrene, divinylbenzene, 1,1-diphenylstyrene, N,N-diethyl-p-aminoethylstyrene, vinyltoluene, and p-tert-butylstyrene. Examples of the conjugated diene compound include butadiene, isoprene, 1,3-pentadiene, and 2,3-dimethyl-1,3-butadiene.

[0095] The modification of the acid-modified styrene-based elastomer (a) can be carried out, for example, by copolymerizing an unsaturated carboxylic acid during polymerization of the styrene-based elastomer. It can also be carried out by heating and kneading the styrene-based elastomer and the unsaturated carboxylic acid in the presence of an organic peroxide. Examples of the unsaturated carboxylic acid include acrylic acid, methacrylic acid, maleic acid, itaconic acid, fumaric acid, maleic anhydride, itaconic anhydride, and fumaric anhydride. The amount of modification by the unsaturated carboxylic acid is preferably 0.1 to 10 mass%.

[0096] The acid value of the acid-modified styrene-based elastomer (a) is preferably 0.1 to 25 mgKOH / g, more preferably 0.5 to 23 mgKOH / g. When the acid value is 0.1 mgKOH / g or more, the adhesive composition is cured sufficiently, and good adhesion, heat resistance, and resin flowability are obtained. On the other hand, when the acid value is 25 mgKOH / g or less, the adhesive strength and electrical properties are excellent.

[0097] The weight average molecular weight of the acid-modified styrene-based elastomer (a) is preferably 10,000 to 500,000, more preferably 30,000 to 300,000, and even more preferably 50,000 to 200,000. When the weight average molecular weight is within the range of 10,000 to 500,000, excellent adhesiveness and electrical properties can be exhibited. In this specification, the weight average molecular weight is a value calculated by converting the molecular weight measured by gel permeation chromatography (hereinafter also referred to as "GPC") into polystyrene.

[0098] Specific examples of the acid-modified styrene-based elastomer (a) include styrene-butadiene block copolymer, styrene-ethylene propylene block copolymer, styrene-butadiene-styrene block copolymer, styrene-isoprene-styrene block copolymer, styrene-ethylenebutylene-styrene block copolymer, and styrene-ethylene propylene-styrene block copolymer modified with unsaturated carboxylic acid. These acid-modified styrene-based elastomers (a) may be used alone or in combination of two or more. Among the copolymers, from the viewpoint of adhesiveness and electrical properties, styrene-ethylenebutylene-styrene block copolymer and styrene-ethylenepropylene-styrene block copolymer are preferred. The mass ratio of styrene / ethylenebutylene in the styrene-ethylenebutylene-styrene block copolymer and the mass ratio of styrene / ethylenepropylene in the styrene-ethylenepropylene-styrene block copolymer are preferably 10 / 90 to 50 / 50, more preferably 20 / 80 to 40 / 60. If the mass ratio is within this range, an adhesive composition having excellent adhesive properties can be obtained.

[0099] The content of the acid-modified styrene-based elastomer (a) is preferably 50 parts by mass or more, more preferably 60 parts by mass or more, based on 100 parts by mass of the solid content of the adhesive composition. When the content of the (a) component is 50 parts by mass or more, the flexibility of the adhesive layer (ii) is good, and warping of the laminate can be suppressed. In addition, the content of the acid-modified styrene-based elastomer (a) is preferably 99 parts by mass or less, more preferably 95% by mass or less, based on 100 parts by mass of the solid content of the adhesive composition.

[0100] <Hardening agent (b)> The adhesive layer (ii) preferably contains a curing agent (b) (hereinafter also referred to as component (b)). The curing agent (b) reacts with the carboxyl group contained in the acid-modified styrene-based elastomer (a) to increase the crosslink density, improving the adhesion to the resin layer (i) and the solder heat resistance, and also acts as a stress relaxation layer between the resin layer (i) and the metal layer (iii), thereby improving the reliability of the adhesion.

[0101] The curing agent (b) is not particularly limited as long as it can react with a carboxy group, and examples thereof include epoxy resins, maleimide resins, oxazoline compounds, polyisocyanates, polycarbodiimide compounds, etc. Among these, epoxy resins, polyisocyanates, and polycarbodiimide compounds are preferred, and one type can be used alone or two or more types can be used in combination. When used in combination, the network becomes dense during crosslinking, improving the solder heat resistance.

[0102] <Epoxy resin> The epoxy resin used in the present invention is not particularly limited as long as it has an epoxy group in the molecule, but preferably has two or more epoxy groups in the molecule.Specific examples include, but are not particularly limited to, aromatic epoxy resins such as biphenyl type epoxy resins, naphthalene type epoxy resins, bisphenol A type epoxy resins, bisphenol F type epoxy resins, and novolac type epoxy resins, alicyclic epoxy resins such as dicyclopentadiene type epoxy resins, amino group-containing epoxy resins such as tetraglycidyl diaminodiphenylmethane, triglycidyl paraaminophenol, tetraglycidyl bisaminomethylcyclohexanone, and N,N,N',N'-tetraglycidyl-m-xylylenediamine, and aliphatic epoxy resins such as epoxy-modified polybutadiene, and these can be used alone or in combination of two or more.Aromatic epoxy resins, alicyclic epoxy resins, and amino group-containing epoxy resins are preferred because they improve solder heat resistance, and more preferably amino group-containing epoxy resins. As the aromatic epoxy resin, a biphenyl type epoxy resin or a novolac type epoxy resin is preferred, and a novolac type epoxy resin is more preferred, and as the alicyclic epoxy resin, a dicyclopentadiene type epoxy resin is preferred.

[0103] The epoxy equivalent of the epoxy resin used in the present invention is preferably 50 g / eq or more, more preferably 70 g / eq or more, and even more preferably 80 g / eq or more. Also, it is preferably 400 g / eq or less, more preferably 350 g / eq or less, and even more preferably 300 g / eq or less. By keeping it within the above range, excellent solder heat resistance can be exhibited.

[0104] In the adhesive layer (ii) of the present invention, the content of the epoxy resin in the curing agent (b) is preferably 0.5 parts by mass or more, more preferably 1 part by mass or more, even more preferably 5 parts by mass or more, and particularly preferably 10 parts by mass or more, relative to 100 parts by mass of the acid-modified styrene-based elastomer. By making it equal to or more than the lower limit, a sufficient curing effect can be obtained, and excellent adhesiveness and solder heat resistance can be expressed. In addition, it is preferably 60 parts by mass or less, more preferably 50 parts by mass or less, and even more preferably 40 parts by mass or less. By making it equal to or less than the upper limit, the low dielectric properties and insulating reliability of the adhesive composition become good. That is, by making it within the above range, an adhesive composition having adhesiveness, solder heat resistance, and excellent low dielectric properties can be obtained.

[0105] <Polycarbodiimide> The polycarbodiimide used in the present invention is not particularly limited as long as it has a carbodiimide group in the molecule, and is preferably a polycarbodiimide having two or more carbodiimide groups in the molecule.

[0106] The polycarbodiimide may be any of aromatic carbodiimide compounds, alicyclic carbodiimide compounds, and aliphatic carbodiimide compounds, which may be used alone or in combination of two or more. Examples of aromatic carbodiimide compounds include poly-m-phenylene carbodiimide, poly-p-phenylene carbodiimide, polytolylene carbodiimide, poly(diisopropylphenylene carbodiimide), poly(methyldiisopropylphenylene carbodiimide), and poly(4,4'-diphenylmethane carbodiimide). Examples of alicyclic carbodiimide compounds include poly-m-cyclohexyl carbodiimide, poly-p-cyclohexyl carbodiimide, poly(4,4'-dicyclohexylmethane carbodiimide), and poly(3,3'-dicyclohexylmethane carbodiimide). Examples of aliphatic carbodiimide compounds may be linear or branched aliphatic carbodiimide compounds. A linear aliphatic carbodiimide compound is preferred, and specific examples thereof include polymethylene carbodiimide, polyethylene carbodiimide, polypropylene carbodiimide, polybutylene carbodiimide, polypentamethylene carbodiimide, and polyhexamethylene carbodiimide. These may be used alone or in combination of two or more. Among these, an aromatic carbodiimide compound or an alicyclic carbodiimide compound is preferred.

[0107] <Polyisocyanate> The polyisocyanate used in the present invention is preferably a polyfunctional isocyanate compound having two or more isocyanate groups in one molecule. Compounds derived from polyfunctional isocyanate compounds can also be used.

[0108] The polyisocyanate may be any of an aromatic isocyanate compound, an alicyclic isocyanate compound, and an aliphatic isocyanate compound, which may be used alone or in combination of two or more. Among them, an aliphatic isocyanate compound is preferred, and an aliphatic diisocyanate compound is more preferred. Examples of aromatic isocyanate compounds include 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 1,3-xylylene diisocyanate, 1,4-naphthalene diisocyanate, 1,5-naphthalene diisocyanate, 1,8-naphthalene diisocyanate, 3,3'-biphenyl diisocyanate, 4,4'-biphenyl diisocyanate, 3,3'-dimethyl-4,4'-biphenyl diisocyanate, diphenylmethane-3,3'-diisocyanate, diphenylmethane-4,4'-diisocyanate, and 3,3'-dimethyldiphenylmethane-4,4'-diisocyanate, and these can be used alone or in combination of two or more. Among these, 3,3'-dimethyl-4,4'-biphenyl diisocyanate is preferred. Examples of the alicyclic isocyanate compound include isophorone diisocyanate, norbornene diisocyanate, 1,2-cyclohexane diisocyanate, 1,3-cyclohexane diisocyanate, 1,4-cyclohexane diisocyanate, dicyclohexylmethane-4,4'-diisocyanate, etc., which can be used alone or in combination of two or more. The aliphatic isocyanate compound can be either a linear or branched aliphatic isocyanate. Preferred are linear aliphatic diisocyanate compounds, specifically 1,3-propane diisocyanate, 1,4-tetramethylene diisocyanate, 1,5-pentamethylene diisocyanate, 1,6-hexamethylene diisocyanate, 1,7-heptamethylene diisocyanate, 1,8-octamethylene diisocyanate, 1,9-nonamethylene diisocyanate, etc., which can be used alone or in combination of two or more. Among them, 1,6-hexamethylene diisocyanate is preferred.

[0109] The polyisocyanate may be an isocyanurate, adduct, biuret, uretdione, or allophanate of the isocyanate compound. The polyisocyanate may be a blocked isocyanate in which the isocyanate group is blocked. These compounds may be used alone or in combination of two or more. Among them, the isocyanurate or biuret is preferable.

[0110] In the adhesive layer (ii) of the present invention, the content of polycarbodiimide and polyisocyanate in the curing agent (b) component is preferably 0.5 parts by mass or more, more preferably 1 part by mass or more, and even more preferably 2 parts by mass or more, relative to 100 parts by mass of the (a) component. By making it equal to or more than the lower limit, an interaction with the substrate is exhibited, and the adhesiveness becomes good. In addition, it is preferably 20 parts by mass or less, more preferably 15 parts by mass or less, and even more preferably 10 parts by mass or less. By making it equal to or less than the upper limit, excellent dielectric properties can be exhibited. That is, by making it within the above range, an adhesive film having excellent low dielectric properties in addition to adhesiveness and solder heat resistance can be obtained.

[0111] <Oligophenylene ether (c)> The oligophenylene ether (c) (hereinafter also referred to as component (c)) used in the present invention is a compound having a repeating unit of a phenylene ether structure, and preferably a compound having a structural unit represented by the following general formula (1) and / or a structural unit represented by the following general formula (2) can be used. [ka]

[0112] In the general formula (1), R1, R2, R3, and R4 are each preferably independently a hydrogen atom, an alkyl group which may be substituted, an alkenyl group which may be substituted, an alkynyl group which may be substituted, an aryl group which may be substituted, an aralkyl group which may be substituted, or an alkoxy group which may be substituted. The "alkyl group" of the alkyl group which may be substituted is, for example, a linear or branched alkyl group having 1 to 6 carbon atoms, preferably 1 to 3 carbon atoms. More specifically, examples of the "alkenyl group" include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, a pentyl group, and a hexyl group, and more preferably a methyl group or an ethyl group. The "alkenyl group" of the alkenyl group which may be substituted is, for example, an ethenyl group, a 1-propenyl group, a 2-propenyl group, a 3-butenyl group, a pentenyl group, and a hexenyl group, and more preferably an ethenyl group or a 1-propenyl group. Examples of the "alkynyl group" of the alkynyl group which may be substituted include, for example, an ethynyl group, a 1-propynyl group, a 2-propynyl (propargyl) group, a 3-butynyl group, a pentynyl group, and a hexynyl group, and more preferably an ethynyl group, a 1-propynyl group, or a 2-propynyl (propargyl) group. Examples of the "aryl group" of the aryl group which may be substituted include, for example, a phenyl group, a naphthyl group, and more preferably a phenyl group. Examples of the "aralkyl group" of the aralkyl group which may be substituted include, for example, a benzyl group, a phenethyl group, a 2-methylbenzyl group, a 4-methylbenzyl group, an α-methylbenzyl group, a 2-vinylphenethyl group, and a 4-vinylphenethyl group, and more preferably a benzyl group. Examples of the "alkoxy group" of the alkoxy group which may be substituted include, for example, a linear or branched alkoxy group having 1 to 6 carbon atoms, preferably 1 to 3 carbon atoms. Examples include a methoxy group, an ethoxy group, a propoxy group, an isopropoxy group, a butoxy group, a sec-butoxy group, a tert-butoxy group, a pentyloxy group, and a hexyloxy group, and a methoxy group or an ethoxy group is more preferable.When the above alkyl group, aryl group, alkenyl group, alkynyl group, aralkyl group, and alkoxy group are substituted, they may have one or more substituents. Examples of such substituents include halogen atoms (e.g., fluorine atom, chlorine atom, bromine atom), alkyl groups having 1 to 6 carbon atoms (e.g., methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, sec-butyl group, tert-butyl group, pentyl group, hexyl group), aryl groups (e.g., phenyl group, naphthyl group), alkenyl groups (e.g., ethenyl group, 1-propenyl group, 2-propenyl group), alkynyl groups (e.g., ethynyl group, 1-propynyl group, 2-propynyl group), aralkyl groups (e.g., benzyl group, phenethyl group), and alkoxy groups (e.g., methoxy group, ethoxy group). Among them, it is preferable that R1 and R4 are methyl groups, and R2 and R3 are hydrogen.

[0113] [ka] In general formula (2), R 11 ,R 12 ,R 13 ,R 14 ,R 15 ,R 16 ,R 17 ,R 18 are preferably each independently a hydrogen atom, an optionally substituted alkyl group, an optionally substituted alkenyl group, an optionally substituted alkynyl group, an optionally substituted aryl group, an optionally substituted aralkyl group, or an optionally substituted alkoxy group. The definition of each substituent is as described above. Examples of the alkyl group include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, a pentyl group, and a hexyl group, and a methyl group is preferable. Among them, R 13 , R 14 , R 17 and R 18 is a methyl group, and R 11 , R 12 , R 15 and R16 is preferably hydrogen. Also, -A- is preferably a linear, branched or cyclic divalent hydrocarbon group having 20 or less carbon atoms, or oxygen. The number of carbon atoms in A is more preferably 1 to 15, and even more preferably 2 to 10. Also, examples of the divalent hydrocarbon group in A include a methylene group, an ethylene group, an n-propylene group, an n-butylene group, a cyclohexylene group, and a phenylene group, and among these, a phenylene group is preferable. Oxygen is particularly preferable.

[0114] The oligophenylene ether (c) may be a modified polyphenylene ether in which a part or all of the oligophenylene ether is functionalized with an ethylenically unsaturated group such as a methacryl group or a vinylbenzyl group, an epoxy group, an amino group, a hydroxyl group, a mercapto group, a carboxyl group, or a silyl group. From the viewpoint of improving the solder heat resistance, it is preferable that both ends have a hydroxyl group, an epoxy group, or an ethylenically unsaturated group. Examples of the ethylenically unsaturated group include alkenyl groups such as ethenyl groups, allyl groups, methacrylic groups, propenyl groups, butenyl groups, hexenyl groups, and octenyl groups, cycloalkenyl groups such as a cyclopentenyl group and a cyclohexenyl group, and alkenylaryl groups such as a vinylbenzyl group and a vinylnaphthyl group. In addition, both ends may be the same functional group or different functional groups. From the viewpoint of precisely controlling the balance between low dielectric tangent and reduction in resin residue, it is preferable that both ends are a hydroxy group, a methacryl group or a vinylbenzyl group, and it is more preferable that both ends are a hydroxy group, a methacryl group or a vinylbenzyl group.

[0115] As a compound having a structural unit represented by general formula (1) or general formula (2), a compound represented by general formula (3) is particularly preferred. [ka] In general formula (3), n is preferably 2 or more, more preferably 3 or more, and is preferably 12 or less, more preferably 11 or less, and even more preferably 10 or less. m is preferably 2 or more, more preferably 3 or more, and is preferably 12 or less, more preferably 11 or less, and even more preferably 10 or less. -A- is the same as in general formula (2).

[0116] Moreover, as the compound having a structural unit represented by general formula (1) or general formula (2), a compound represented by general formula (4) or general formula (5) is particularly preferable. [ka] In general formula (4), n is preferably 2 or more, more preferably 3 or more, and is preferably 12 or less, more preferably 11 or less, and even more preferably 10 or less. m is preferably 2 or more, more preferably 3 or more, and is preferably 12 or less, more preferably 11 or less, and even more preferably 10 or less. -A- is the same as in general formula (2). [ka] In general formula (5), n is preferably 2 or more, more preferably 3 or more, and is preferably 12 or less, more preferably 11 or less, and even more preferably 10 or less. m is preferably 2 or more, more preferably 3 or more, and is preferably 12 or less, more preferably 11 or less, and even more preferably 10 or less. -A- is the same as in general formula (2).

[0117] The number average molecular weight of the oligophenylene ether (c) is preferably 3000 or less, more preferably 2700 or less, and even more preferably 2500 or less. The number average molecular weight of the oligophenylene ether is preferably 500 or more, and more preferably 700 or more. By setting the number average molecular weight of the oligophenylene ether to the lower limit or more, the flexibility of the obtained adhesive layer can be improved. On the other hand, by setting the number average molecular weight of the oligophenylene ether to the upper limit or less, the solubility in organic solvents can be improved.

[0118] The content of the oligophenylene ether (c) is preferably 0.05 parts by mass or more relative to 100 parts by mass of the (a) component. More preferably, it is 1 part by mass or more, and even more preferably, it is 5 parts by mass or more. By making it equal to or more than the lower limit, excellent solder heat resistance can be exhibited. Also, it is preferably 200 parts by mass or less. More preferably, it is 150 parts by mass or less, even more preferably, it is 100 parts by mass or less, and particularly preferably, it is 50 parts by mass or less. By making it equal to or less than the upper limit, excellent adhesion and solder heat resistance can be exhibited.

[0119] <Acid-modified polyolefin resin (d)> The acid-modified polyolefin resin (d) (hereinafter also referred to as component (d)) used in the present invention can be used as a means for adjusting the elastic modulus (tackiness) of the adhesive layer (ii). By further adding the acid-modified polyolefin resin (d) to an adhesive composition comprising an acid-modified styrene-based elastomer (a), a curing agent (b), and an oligophenylene ether (c) added thereto, the elastic modulus of the adhesive layer (ii) can be adjusted, making it easier to laminate the adhesive layer (ii) on the resin layer (i) and / or the metal layer (iii), and reducing the tackiness.

[0120] The acid-modified polyolefin resin (d) used in the present invention is not limited, but is preferably one obtained by grafting at least one of α,β-unsaturated carboxylic acid and its acid anhydride to a polyolefin resin. The polyolefin resin refers to a polymer mainly composed of a hydrocarbon skeleton, such as a homopolymer of an olefin monomer exemplified by ethylene, propylene, butene, butadiene, isoprene, etc., or a copolymer with other monomers, and a hydrogenated or halogenated product of the obtained polymer. That is, the acid-modified polyolefin resin (a) is preferably one obtained by grafting at least one of α,β-unsaturated carboxylic acid and its acid anhydride to at least one of polyethylene, polypropylene, and propylene-α-olefin copolymer.

[0121] Propylene-α-olefin copolymer is a copolymer of propylene as a main component with α-olefin. As the α-olefin, for example, one or more of ethylene, 1-butene, 1-heptene, 1-octene, 4-methyl-1-pentene, vinyl acetate, etc. can be used. Among these α-olefins, ethylene and 1-butene are preferred. The ratio of the propylene component to the α-olefin component in the propylene-α-olefin copolymer is not limited, but the propylene component is preferably 50 mol% or more, more preferably 70 mol% or more.

[0122] At least one of the α,β-unsaturated carboxylic acids and their acid anhydrides may be, for example, maleic acid, itaconic acid, citraconic acid, and their acid anhydrides. Among these, acid anhydrides are preferred, and maleic anhydride is more preferred. That is, the acid-modified polyolefin resin (c) may specifically be maleic anhydride-modified polypropylene, maleic anhydride-modified propylene-ethylene copolymer, maleic anhydride-modified propylene-butene copolymer, maleic anhydride-modified propylene-ethylene-butene copolymer, etc., and these maleic anhydride-modified polyolefins may be used alone or in combination of two or more.

[0123] From the viewpoint of solder heat resistance and adhesion to the resin layer (i) and the metal layer (iii), the acid value of the acid-modified polyolefin resin (d) is preferably 5 mgKOH / g or more, more preferably 6 mgKOH / g or more, even more preferably 7 mgKOH / g or more, and particularly preferably 10 mgKOH / g or more. By making it equal to or more than the lower limit, the reactivity with the curing agent (b) becomes good, and excellent adhesive strength can be expressed. In addition, the crosslinking density is high, and the solder heat resistance becomes good. The upper limit is preferably 30 mgKOH / g or less, more preferably 28 mgKOH / g or less, and even more preferably 25 mgKOH / g or less. By making it equal to or less than the upper limit, the adhesiveness becomes good. In addition, the viscosity and stability of the solution become good, and excellent pot life can be expressed. Furthermore, the manufacturing efficiency is improved.

[0124] The number average molecular weight (Mn) of the acid-modified polyolefin resin (d) is preferably in the range of 10,000 to 50,000. More preferably, it is in the range of 15,000 to 45,000, even more preferably, it is in the range of 20,000 to 40,000, and particularly preferably, it is in the range of 22,000 to 38,000. By making it equal to or more than the lower limit, the cohesive force becomes good and excellent adhesiveness can be exhibited. On the other hand, by making it equal to or less than the upper limit, excellent flowability and operability can be obtained.

[0125] The acid-modified polyolefin resin (d) is preferably crystalline. The term "crystalline" as used herein refers to a resin that exhibits a clear melting peak during heating from -100°C to 250°C at a rate of 20°C / min using a differential scanning calorimeter (DSC).

[0126] The melting point (Tm) of the acid-modified polyolefin resin (d) is preferably in the range of 50°C to 120°C, more preferably in the range of 60°C to 100°C, and most preferably in the range of 70°C to 90°C. By making it equal to or higher than the lower limit, the cohesive force derived from crystals becomes good, and excellent adhesiveness and solder heat resistance can be exhibited. In addition, by making it equal to or lower than the upper limit, excellent solution stability and flowability are achieved, and operability during adhesion is improved.

[0127] The heat of fusion (ΔH) of the acid-modified polyolefin resin (d) is preferably in the range of 5 J / g to 60 J / g. More preferably, it is in the range of 10 J / g to 50 J / g, and most preferably, it is in the range of 20 J / g to 40 J / g. By making it equal to or greater than the lower limit, the cohesive force derived from crystals becomes good, and excellent adhesiveness and solder heat resistance can be exhibited. In addition, by making it equal to or less than the upper limit, excellent solution stability and flowability are obtained, and operability during adhesion is good.

[0128] The method for producing the acid-modified polyolefin resin (d) is not particularly limited, and examples thereof include a radical graft reaction (i.e., a reaction in which radical species are generated on a polymer that is to become the main chain, and an unsaturated carboxylic acid and an acid anhydride are graft polymerized using the radical species as a polymerization initiation point).

[0129] As the radical generator, although not particularly limited, it is preferable to use an organic peroxide.As the organic peroxide, although not particularly limited, peroxides such as di-tert-butyl peroxyphthalate, tert-butyl hydroperoxide, dicumyl peroxide, benzoyl peroxide, tert-butyl peroxybenzoate, tert-butyl peroxy-2-ethylhexanoate, tert-butyl peroxypivalate, methyl ethyl ketone peroxide, di-tert-butyl peroxide, lauroyl peroxide, etc.; azonitriles such as azobisisobutyronitrile, azobisisopropionitrile, etc. can be mentioned.

[0130] <Adhesive composition> The adhesive composition used in the adhesive layer (ii) of the present invention is preferably a composition containing the above-mentioned components (a) and (b), and, if necessary, the component (c) and / or the component (d). By containing the above-mentioned components, the adhesive composition exhibits excellent adhesion to both the resin layer (i) and the metal layer (iii), and can exhibit electrical properties (low dielectric properties) and solder heat resistance. That is, the adhesive layer (ii) after being applied to the resin layer (i) and / or the metal layer (iii) and cured can exhibit excellent low dielectric properties and solder heat resistance.

[0131] The adhesive composition of the present invention may further contain an organic solvent. The organic solvent used in the present invention is not particularly limited as long as it dissolves the acid-modified styrene-based elastomer (a), the curing agent (b), and the oligophenylene ether (c) or the acid-modified polyolefin resin (d). Specific examples of the organic solvent include aromatic hydrocarbons such as benzene, toluene, and xylene, aliphatic hydrocarbons such as hexane, heptane, octane, and decane, alicyclic hydrocarbons such as cyclohexane, cyclohexene, methylcyclohexane, and ethylcyclohexane, halogenated hydrocarbons such as trichloroethylene, dichloroethylene, chlorobenzene, and chloroform, alcohol solvents such as methanol, ethanol, isopropyl alcohol, butanol, pentanol, hexanol, propanediol, and phenol, acetone, methyl isobutyl ketone, methyl ethyl ketone, pentanone, hexanone, cyclohexanone, isophorone, and acetophenone. Ketone-based solvents, cellosolves such as methyl cellosolve and ethyl cellosolve, ester-based solvents such as methyl acetate, ethyl acetate, butyl acetate, methyl propionate, and butyl formate, glycol ether-based solvents such as ethylene glycol mono-n-butyl ether, ethylene glycol mono-iso-butyl ether, ethylene glycol mono-tert-butyl ether, diethylene glycol mono-n-butyl ether, diethylene glycol mono-iso-butyl ether, triethylene glycol mono-n-butyl ether, and tetraethylene glycol mono-n-butyl ether, and the like can be used, and one or more of these can be used in combination. In particular, methylcyclohexane and toluene are preferred from the viewpoints of working environment and drying properties.

[0132] The organic solvent is preferably in the range of 100 to 1000 parts by mass, more preferably in the range of 200 to 900 parts by mass, and most preferably in the range of 300 to 800 parts by mass, relative to 100 parts by mass of the acid-modified styrene-based elastomer (a). By making it equal to or more than the lower limit, the liquid state and pot life are improved. Also, by making it equal to or less than the upper limit, it is advantageous in terms of production costs and transportation costs.

[0133] The adhesive layer (ii) according to the present invention has a relative dielectric constant (ε c ) is preferably 3.0 or less, more preferably 2.6 or less, and even more preferably 2.3 or less. There is no particular lower limit, but it is practically 2.0. In addition, the relative dielectric constant (ε c ) is preferably 3.0 or less, more preferably 2.6 or less, and even more preferably 2.3 or less.

[0134] The adhesive layer (ii) according to the present invention preferably has a dielectric loss tangent (tan δ) of 0.02 or less at a frequency of 10 GHz. More preferably, it is 0.01 or less, and even more preferably, it is 0.008 or less. There is no particular lower limit, but in practice, it is 0.0001. Moreover, the dielectric loss tangent (tan δ) over the entire frequency range of 1 GHz to 60 GHz is preferably 0.02 or less, more preferably 0.01 or less, and even more preferably 0.008 or less.

[0135] In the present invention, the relative dielectric constant (ε c The dielectric constant (ε) and dielectric tangent (tan δ) can be measured as follows. That is, the adhesive composition is applied to a release substrate so that the thickness after drying is 25 μm, and dried at about 130° C. for about 5 minutes. Then, the adhesive composition is cured by heat treatment at about 180° C. for about 1 hour, and the cured adhesive composition layer (adhesive layer (ii)) is peeled off from the release film. The relative dielectric constant (ε) at a frequency of 10 GHz of the adhesive composition layer after peeling is measured. c Specifically, the relative dielectric constant (ε c ) and dielectric tangent (tan δ) can be calculated.

[0136] The dielectric constant and dielectric loss tangent of the adhesive layer (ii) may be measured by removing only the adhesive layer (ii) from the laminate. The method for removing the adhesive layer (ii) is not particularly limited, and for example, the metal layer (iii) may be removed by etching, and the resin layer (i) may be dissolved and removed with a solvent or scraped off. The adhesive layer (ii) removed from the laminate may be subjected to a dynamic viscoelasticity test by itself.

[0137] In addition, the storage modulus at room temperature of the adhesive composition layer (adhesive layer (ii)) cured under the above conditions was 0.5×10 6 Pa or more, 1.5×10 8 It is preferable that the pressure is 1×10 Pa or less, because it is easy to laminate the resin layer (i) and / or the metal layer (iii). 7 Pa or more, and more preferably 3×10 7 Pa or more. More preferably, it is 1.2×10 8 Pa or less, and more preferably 1×10 8 Pa or less. The storage modulus is 0.5×10 6 When the storage modulus is 1.5×10 Pa or more, the tackiness is not too strong, so that the resin layer (i) is easily peeled off from the release paper, and the resin layer (i) and the metal layer (iii) are easily bonded to each other. 8 If the pressure is less than or equal to Pa, the adhesive layer (ii) will not become too hard, and therefore the resin layer (i) and the metal layer (iii) can be easily relaxed when they are bonded together, thereby suppressing warping of the laminate and wrinkles on the surface of the metal layer (iii), which is the outermost surface of the laminate.

[0138] The adhesive composition of the present invention may further contain other components as necessary within the range that does not impair the effects of the present invention. Specific examples of such components include inorganic fillers, tackifiers, and silane coupling agents.

[0139] <Inorganic fillers> The adhesive composition of the present invention may contain an inorganic filler as necessary within a range that does not impair the effects of the present invention. By containing this component, the solder heat resistance of the laminate produced with the adhesive composition is improved. As the inorganic filler, a filler is preferable, and a silica filler (hereinafter, also simply referred to as silica) is more preferable. By adding silica, the solder heat resistance characteristics are improved, which is very preferable. As silica, hydrophobic silica and hydrophilic silica are generally known, and examples of hydrophobic silica include silica treated with dimethyldichlorosilane, hexamethyldisilazane, octylsilane, etc., and hydrophobic silica can impart moisture absorption resistance to the adhesive composition. Examples of hydrophilic silica include untreated silica having a silanol group or siloxane on the surface.

[0140] The average particle size of the inorganic filler is preferably 0.01 to 10 μm, more preferably 0.02 to 5 μm, and further preferably 0.1 to 1 μm. The average particle size (median size) can be measured on a volume basis using a laser diffraction / scattering type particle size distribution measuring device.

[0141] In the adhesive composition of the present invention, the content of the inorganic filler is preferably in the range of 2 to 50 parts by mass, more preferably in the range of 3 to 45 parts by mass, and even more preferably in the range of 5 to 40 parts by mass, relative to 100 parts by mass of the total of the components (a) to (c). By keeping the content within this range, the adhesive composition has good adhesion, solder heat resistance, and electrical properties.

[0142] <Tackifier> The adhesive composition of the present invention may contain a tackifier as necessary within a range that does not impair the effects of the present invention. Examples of tackifiers include polyterpene resins, rosin resins, aliphatic petroleum resins, alicyclic petroleum resins, copolymerized petroleum resins, styrene resins, and hydrogenated petroleum resins, and are used for the purpose of improving adhesive strength. These may be used alone or in any combination of two or more. When a tackifier is contained, it is preferably contained in a range of 1 to 200 parts by mass, more preferably in a range of 5 to 150 parts by mass, and most preferably in a range of 10 to 100 parts by mass, relative to 100 parts by mass of the total of components (a) to (c). By making it equal to or more than the lower limit, the effect of the tackifier can be exhibited. Also, by making it equal to or less than the upper limit, the adhesiveness, solder heat resistance, electrical properties, etc. are not reduced.

[0143] <Silane coupling agent> The adhesive composition of the present invention may contain a silane coupling agent as necessary within a range that does not impair the effects of the present invention. The incorporation of a silane coupling agent is highly preferable because it improves the adhesiveness to metals and solder heat resistance. The silane coupling agent is not particularly limited, but examples thereof include those having an unsaturated group, those having a glycidyl group, and those having an amino group. Among these, silane coupling agents having a glycidyl group such as γ-glycidoxypropyltrimethoxysilane, β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, and β-(3,4-epoxycyclohexyl)ethyltriethoxysilane are more preferable from the viewpoint of solder heat resistance. When a silane coupling agent is incorporated, the amount of the silane coupling agent is preferably 0.5 to 20 parts by mass relative to 100 parts by mass of the total of the components (a) to (c). By making it 0.5 parts by mass or more, excellent solder heat resistance is obtained. On the other hand, by making it 20 parts by mass or less, solder heat resistance and adhesiveness are improved.

[0144] <Adhesive sheet> In the present invention, the adhesive sheet is a precursor for preparing the adhesive layer (ii), and is obtained by applying an adhesive composition onto a release substrate, drying it to partially cure it, and then laminating a release substrate on top of it. A specific configuration can be a release substrate / adhesive layer / release substrate. Laminating the release substrate functions as a protective layer for the substrate or adhesive layer. In addition, by using a release substrate, the release substrate can be released from the adhesive sheet, and the adhesive layer can be transferred to another substrate.

[0145] The adhesive composition of the present invention can be applied to various laminates and dried in a conventional manner to obtain the adhesive sheet of the present invention. After drying, a release substrate is attached to the adhesive layer, which allows winding without causing offset onto the substrate, resulting in excellent operability, and the adhesive layer is protected, resulting in excellent storage stability and ease of use. After application to a release substrate and drying, the adhesive layer itself can be transferred to another substrate by attaching another release substrate as necessary.

[0146] The thickness of the adhesive sheet is preferably in the range of 5 to 200 μm, more preferably 8 to 150 μm, more preferably 10 to 100 μm, and most preferably 12 to 80 μm. If the thickness of the adhesive sheet is less than 5 μm, pinholes are likely to occur, and if the thickness is more than 200 μm, unevenness in the film thickness may become significant.

[0147] <Release base material> The release substrate is not particularly limited, but examples thereof include those in which a coating layer of a filler such as clay, polyethylene, or polypropylene is provided on both sides of paper such as fine paper, craft paper, roll paper, or glassine paper, and a silicone-based, fluorine-based, or alkyd-based release agent is further applied on each coating layer. Other examples include various olefin films such as polyethylene, polypropylene, ethylene-α-olefin copolymer, and propylene-α-olefin copolymer alone, and films such as polyethylene terephthalate on which the release agent is applied. Due to the release force between the release substrate and the adhesive layer, and the adverse effect of silicone on electrical properties, it is preferable to use a polypropylene-filled coating on both sides of fine paper and an alkyd-based release agent on the polypropylene, or an alkyd-based release agent on polyethylene terephthalate.

[0148] In the present invention, the method of coating the adhesive composition on the substrate is not particularly limited, but includes a comma coater, a reverse roll coater, and the like. Alternatively, if necessary, the adhesive layer can be provided directly or by a transfer method on the rolled copper foil or polyimide film, which is a printed wiring board constituent material. The thickness of the adhesive layer after drying is appropriately changed as necessary, but is preferably in the range of 5 to 200 μm. If the adhesive film thickness is less than 5 μm, the adhesive strength is insufficient. If it is 200 μm or more, there is a problem that the drying is insufficient, the residual solvent increases, and blisters occur during pressing in the production of the printed wiring board. The drying conditions are not particularly limited, but the residual solvent rate after drying is preferably 1 mass % or less. If it exceeds 1 mass %, there is a problem that the residual solvent foams during pressing of the printed wiring board, causing blisters.

[0149] <Metal layer (iii)> As the metal layer (iii), any conventionally known conductive material that can be used for a circuit board can be used. Examples of materials include various metals such as SUS, copper, aluminum, iron, steel, zinc, and nickel, as well as their alloys, plated products, and metals treated with other metals such as zinc and chromium compounds. Metal foils are preferred, and copper foils are more preferred. Types of copper foil include electrolytic foils and rolled foils, and either type of copper foil can be used in the laminate for electronic circuit boards of the present invention.

[0150] The surface roughness (Rz) of the surface of the metal layer (iii) in contact with the adhesive layer (ii) is preferably in the range of 0.1 μm to 7.0 μm, more preferably in the range of 0.3 μm to 5.0 μm, even more preferably in the range of 0.5 μm to 3.0 μm, and most preferably in the range of 0.8 μm to 1.5 μm. By keeping the surface roughness within the above range, both excellent adhesion and transmission loss can be achieved, and the laminate can be suitably used for electronic circuit boards.

[0151] The thickness of the metal layer (iii) is preferably 1 μm or more, preferably 3 μm or more, more preferably 10 μm or more. Also, it is preferably 50 μm or less, more preferably 30 μm or less, and even more preferably 25 μm or less. By making the thickness 1 μm or more, sufficient electrical performance of the electronic circuit can be obtained, while by making the thickness 50 μm or less, the processing efficiency during the manufacture of the electronic circuit can be improved. The metal foil is usually provided in a rolled form. The form of the metal foil used in manufacturing the printed wiring board of the present invention is not particularly limited. When a ribbon-shaped metal foil is used, its length is not particularly limited. Also, its width is not particularly limited, but is preferably about 250 to 500 cm.

[0152] <Laminate> The laminate of the present invention is a laminate in which a resin layer (i), an adhesive layer (ii), and a metal layer (iii) are laminated in this order. The peel strength between the resin layer (i) and the adhesive layer (ii) must be 0.3 kN / m or more. Since the durability of the laminate is good, it is preferably 0.4 kN / m or more, and more preferably 0.5 kN / m or more. There is no particular upper limit, but if it is used for electronic circuit boards, 2 kN / m or less is sufficient, and 1.5 kN / m or less is also acceptable.

[0153] The laminate of the present invention may be formed by laminating the resin layer (i), adhesive layer (ii), and metal layer (iii) in this order, and other layers may be laminated between the resin layer (i) and adhesive layer (ii), or other layers may be laminated between the adhesive layer (ii) and metal layer (iii). Preferably, the laminate is formed by directly laminating the resin layer (i), adhesive layer (ii), and metal layer (iii). Also, the adhesive layer (ii) and metal layer (iii) may be laminated on both sides of the resin layer (i) in this order (for example, a laminate of "metal layer (iii) / adhesive layer (ii) / resin layer (i) / adhesive layer (ii) / metal layer (iii)". When the adhesive layer (ii) and the metal layer (iii) are laminated on both sides of the resin layer (i), it is preferable that the resin layer (i) is the innermost layer. In the case of such a laminate on both sides, other layers may be laminated between the resin layer (i), the adhesive layer (ii) and / or the metal layer (iii), or the resin layer (i), the adhesive layer (ii) and the metal layer (iii) may be directly laminated to form a laminate. EXAMPLES

[0154] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. In the following examples, parts and % are by weight unless otherwise specified.

[0155] (1) Evaluation method for raw material characteristics The characteristics of the raw materials used in the examples were evaluated using the following 1 to 3. For other characteristics, the nominal values ​​listed in the catalog values ​​of the raw material manufacturers are listed.

[0156] 1. Acid value The acid value (mgKOH / g) in the present invention is a value obtained by dissolving a resin sample in toluene and titrating it with a methanol solution of sodium methoxide using phenolphthalein as an indicator.

[0157] 2.Number average molecular weight (Mn) The number average molecular weight in the present invention is a value measured by gel permeation chromatography (hereinafter, GPC, standard substance: polystyrene resin, mobile phase: tetrahydrofuran, column: Shodex KF-802 + KF-804L + KF-806L, column temperature: 30°C, flow rate: 1.0 ml / min, detector: refractive index (RI) detector) manufactured by Shimadzu Corporation.

[0158] 3. Measurement of melting point (Tm), heat of fusion (ΔH), and glass transition temperature (Tg) The melting point and heat of fusion in the present invention are values ​​measured using a differential scanning calorimeter (hereinafter referred to as DSC, manufactured by TA Instruments Japan, Q-2000) from the top temperature and area of ​​the melting peak when the material is heated and melted at a rate of 20°C / min, cooled to resinify, and then heated and melted again. The glass transition temperature is the temperature at the start (rise) of the endothermic peak during the heating process.

[0159] (2) Raw materials used in the examples and comparative examples [Adhesive layer (i)] <Styrene polymer (A) having a syndiotactic structure> A1: XAREC (registered trademark) 130ZC (Idemitsu Kosan Co., Ltd., 100% syndiotactic polystyrene by mass, MFR = 15 g / 10 min, measurement temperature: 300°C, load: 1.2 kg, not modified by a compound having a polar group, melting point: 272°C, glass transition temperature: 97°C) A2: XAREC (registered trademark) 90ZC (Idemitsu Kosan Co., Ltd., 100% syndiotactic polystyrene by mass, MFR = 9 g / 10 min, measurement temperature: 300°C, load: 1.2 kg, not modified by a compound having a polar group, melting point: 271°C, glass transition temperature: 96°C)

[0160] <Rubber-like elastic body (B)> B1: Tuftec (registered trademark) H1062 (manufactured by Asahi Kasei Corporation, styrene ratio = 18 mass%, MFR = 4.5 g / 10 min, measurement temperature: 230 ° C, load: 2.16 kg) B2: Tuftec (registered trademark) H1041 (manufactured by Asahi Kasei Corporation, styrene ratio = 30 mass%, MFR = 5.0 g / 10 min, measurement temperature: 230 ° C, load: 2.16 kg) B3: Tuftec (registered trademark) H1517 (manufactured by Asahi Kasei Corporation, styrene ratio = 43 mass%, MFR = 3.0 g / 10 min, measurement temperature: 230 ° C, load: 2.16 kg) B4: Tuftec (registered trademark) H1521 (manufactured by Asahi Kasei Corporation, styrene ratio = 18 mass%, MFR = 15.0 g / 10 min, measurement temperature: 230°C, load: 2.16 kg)

[0161] <Fibrous filler (C)> C1: HDT09100T (made by Tochu Co., Ltd., fiber diameter: 9 μm, D50 average fiber length: 100 μm, D glass) C2: EPH80M-01N (Nippon Electric Glass Co., Ltd., fiber diameter: 10 μm, D50 average fiber length: 80 μm, E glass) C3: EFH30-01 (Central Glass Fiber Co., Ltd., fiber diameter: 11 μm, D50 average fiber length: 30 μm, E-glass) ·C4:ECS301HP-3-H (manufactured by Chongqing International Composite Materials Co., Ltd., fiber diameter (diameter): 10μm, D50 average fiber length: 3000μm, E glass) C5: ChopVantageHP-3610 (Nippon Electric Glass Co., Ltd., fiber diameter: 10 μm, D50 average fiber length: 4500 μm, E-glass)

[0162] <Non-fibrous filler (D)> D1: Silica particles: FB-3SDC (manufactured by Denka Co., Ltd., D50 average particle size: 3.1 μm) D2: Silica particles: FB-7SDC (manufactured by Denka Co., Ltd., D50 average particle size: 5.4 μm) D3: Silica particles: SFP-130MC (manufactured by Denka Co., Ltd., D50 average particle size: 0.6 μm) D4: Hollow glass beads: iM-30k (manufactured by 3M Japan Co., Ltd., D50 average particle size: 17 μm) D5: Calcium carbonate: Whiten P-30 (Shiraishi Calcium Industry Co., Ltd., D50 average particle size: 4.8 μm) D6: Magnesia: RF-98 (Ube Material Industries, Ltd., D50 average particle size: 50 μm)

[0163] <Antioxidants (E)> E1: ANOX20 (manufactured by BASF Japan Ltd., pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] E2: PEP-36 (ADEKA Corporation, 3,9-bis(2,6-di-tert-butyl-4-methylphenoxy)-2,4,8,10-tetraoxa-3,9-diphosphaspiro[5.5]undecane)

[0164] [Adhesive layer (ii)] <Acid-modified styrene-based elastomer (a)> a1: Tuftec (registered trademark) H1943 (manufactured by Asahi Kasei Corporation, styrene ratio = 20 mass%, MFR = 8.0 g / 10 min (measurement conditions: measurement temperature: 230 ° C., load: 2.16 kg), acid value = 10 mg KOH / g) a2: Tuftec (registered trademark) H1913 (manufactured by Asahi Kasei Corporation, styrene ratio = 30 mass%, MFR = 5.0 g / 10 min (measurement conditions: measurement temperature: 230 ° C., load: 2.16 kg), acid value = 10 mg KOH / g) a3: Tuftec (registered trademark) C5025 (manufactured by Asahi Kasei Corporation, styrene ratio = 12 mass%, MFR = 10.0 g / 10 min (measurement conditions: measurement temperature: 230 ° C, load: 2.16 kg), acid value = 4 mg KOH / g)

[0165] <Unmodified styrene elastomer (α)> α1: Tuftec (registered trademark) H1041 (manufactured by Asahi Kasei Corporation, styrene ratio = 30 mass%, MFR = 5.0 g / 10 min (measurement conditions: measurement temperature: 230 ° C, load: 2.16 kg), acid value = 0 mg KOH / g)

[0166] <Hardening agent (b)> b1: Cresol novolac epoxy resin: JER-152 (manufactured by Mitsubishi Chemical Corporation, epoxy equivalent = 177g / eq) b2: Dicyclopentadiene type epoxy resin: HP-7200 (DIC, epoxy equivalent = 259g / eq) b3: Polycarbodiimide resin: V-09GB (Nisshinbo Chemical Co., Ltd., carbodiimide equivalent = 216g / eq)

[0167] <Oligophenylene ether (c)> c1: Modified oligophenylene ether styrene: OPE-2St 1200 (manufactured by Mitsubishi Gas Chemical Co., Ltd., a compound having the structure of general formula (4) with Mn=1000) c2: Modified oligophenylene ether styrene: OPE-2St 2200 (manufactured by Mitsubishi Gas Chemical Co., Ltd., a compound having the structure of general formula (4) with Mn=2000) c3: Oligophenylene ether: PPO640 (SABIC, Mn=18000 A compound having a structure represented by the general formula (3):

[0168] <Acid-modified polyolefin (d)> d1: Manufacturing example 1 In a 1L autoclave, 100 parts by mass of propylene-butene copolymer (Mitsui Chemicals' "Tafmer (registered trademark) XM7080"), 150 parts by mass of toluene, 19 parts by mass of maleic anhydride, and 6 parts by mass of di-tert-butyl peroxide were added, and the temperature was raised to 140 ° C., followed by stirring for another 3 hours. After that, the obtained reaction liquid was cooled and poured into a container containing a large amount of methyl ethyl ketone to precipitate a resin. Then, the liquid containing the resin was centrifuged to separate and purify the acid-modified propylene-butene copolymer in which maleic anhydride was graft-polymerized, (poly) maleic anhydride, and low molecular weight substances. Then, the mixture was dried under reduced pressure at 70 ° C. for 5 hours to obtain a maleic anhydride-modified propylene-butene copolymer (CO-1, acid value 19 mg KOH / g, number average molecular weight 25,000, Tm 80 ° C., △H 35 J / g).

[0169] ·d2: Manufacturing example 2 A maleic anhydride-modified propylene-butene copolymer (CO-2, acid value 11 mgKOH / g, number average molecular weight 33,000, Tm 80°C, △H 25 J / g) was obtained by the same procedure as in Production Example 1, except that the amount of maleic anhydride added was changed to 11 parts by mass.

[0170] d3: Manufacturing example 3 A maleic anhydride-modified propylene-butene copolymer (CO-3, acid value 7 mgKOH / g, number average molecular weight 35,000, Tm 82°C, △H 25 J / g) was obtained by the same procedure as in Production Example 1, except that the amount of maleic anhydride added was changed to 6 parts by mass.

[0171] [Metal layer (iii)] ·I: Low roughness copper foil, manufactured by Fukuda Metal Foil & Powder Industry Co., Ltd., CF-T4X-SV18, Thickness=18μm, Rz=1.1μm ·II: Low roughness copper foil, manufactured by Fukuda Metal Foil & Powder Industry Co., Ltd., CF-T9DA-SV-18, Thickness=18μm, Rz=0.9μm III: Copper foil, Furukawa Electric Co., Ltd., DGTSEU2, thickness = 18 μm, Rz = 3.2 μm IV: Copper foil, Furukawa Electric Co., Ltd., GTS-MP, thickness = 18 μm, Rz = 8.0 μm

[0172] <Method of producing polystyrene-based resin composition> In order to obtain a sheet or film that is a precursor of the resin layer (i) of the present invention, a polystyrene-based resin composition (SPS resin composition) was produced. The composition was obtained by blending and kneading each component (A) including SPS, or the above-mentioned various components (B) to (E) with (A).

[0173] More specifically, (A) and (B) to (E) were each fed into a 36 mmφ co-rotating twin-screw extruder (resin temperature: 300°C) through the main feeder or side feeder to compound the components, and then extruded through a circular die to extrude four φ4 mm strands. The strands were then cooled and solidified in a water-cooled bath and cut to obtain cylindrical pellets of the SPS resin composition.

[0174] <Sheet manufacturing method> The pellets of the SPS resin composition obtained by the above manufacturing method were put into the hopper of a φ20 mm single screw extruder (resin temperature: 300°C) and remelted, extruded from a T-die into a sheet, sandwiched between two rolls, a metal touch roll and a take-up roll (temperature: 90°C), compressed and cooled to solidify, and then taken up at a speed of 1 m / min onto a paper tube with a diameter of 80 mm to obtain an unstretched SPS sheet with a thickness of 300 μm. In this case, the winding properties of the sheet were evaluated as follows: no sticking to the chill roll and no thickness unevenness on the sheet surface (◯); sticking to the roll or thickness unevenness on the sheet surface (△); no sticking to the roll but thickness unevenness or small cracks on the sheet surface (△△); and sticking to the roll or cracks on the sheet surface that made it impossible to wind the sheet (×). Hereinafter, the direction parallel to the extrusion direction of the sheet is defined as MD, and the direction perpendicular to the extrusion direction of the sheet is defined as TD.

[0175] <Heat treatment and humidity adjustment process> By heat treating the obtained unstretched SPS sheet, the crystallinity of component (A) contained in the SPS sheet can be increased, and the solder heat resistance of the SPS sheet can be improved. The SPS sheet obtained by the above manufacturing method was sandwiched between a commercially available polyimide film (Upilex, manufactured by Ube Industries, Ltd.) and a silicone sheet (MSF-100, manufactured by Chukoh Chemical Industries, Ltd., thickness: 100 μm) and compressed and heated using a hydraulic hand press (temperature: 200°C, time: 30 min, pressure: 2.0 MPa). The obtained heat-treated SPS sheet (hereafter referred to as the heat-treated sheet) was subjected to humidity conditioning treatment for 24 hours in an environment of 23°C x 50% RH to remove the effects of humidity and obtain a sample with little variation due to external factors.

[0176] In order to confirm whether the crystallization of the heat-treated sheet and biaxially stretched film was completed, a differential scanning calorimeter (DSC7020, Hitachi High-Tech Science Corporation) was used to perform evaluation in accordance with JISK7121 (2012). More specifically, when 5 mg of the sheet molded body was packed in an aluminum pan and heated from room temperature at a rate of 20°C / min, it was confirmed that no exothermic peak was observed in the temperature range of 100 to 220°C, and it was confirmed that the crystallization was completed by the heat treatment during pressing.

[0177] <Film manufacturing method> For Examples 30 to 33 and Comparative Examples 11 to 13 The components (A) to (E) in the mixing ratios (parts by mass) shown in the table were compounded by feeding them into a 36 mmφ unidirectional twin screw extruder (resin temperature: 300°C) from the main feeder or side feeder, and then strands were extruded from four round dies (φ4 mm each), which were cooled and solidified in a water-cooled bath and cut to obtain cylindrical pellets of the SPS resin composition. The pellets of the SPS resin composition were fed into the hopper of a φ20 mm single screw extruder (resin temperature: 300°C) and remelted, extruded into a sheet from a T-die, cooled with a metal cooling roll (temperature: 30°C), and wound up at a speed of 3 m / min on a paper tube with a diameter of 80 mm to obtain a 500 μm thick unstretched SPS sheet (hereinafter sometimes referred to as precursor SPS sheet) that would serve as a precursor of the stretched film. Next, the unstretched sheet was subjected to the stretching and relaxation treatments shown in Production Examples A to G below to produce biaxially stretched films.

[0178] Manufacturing Example A (for Example 30) After obtaining an unstretched SPS sheet with a thickness of 500 μm, it was subjected to simultaneous biaxial stretching (temperature: 110°C, stretch ratio: 3.3×3.4 (MD×TD), stretching speed: 500% / min), and then subjected to relaxation heat treatment in a thermal drying oven (temperature: 230°C, relaxation ratio: 0.93×0.95 (MD×TD)) to obtain a biaxially stretched SPS film with a thickness of 50 μm.

[0179] Production Example B (for Example 31) After obtaining an unstretched SPS sheet with a thickness of 500 μm, it was subjected to simultaneous biaxial stretching (temperature: 110°C, stretch ratio: 3.3×3.4 (MD×TD), stretching speed: 500% / min), and then subjected to relaxation heat treatment in a thermal drying oven (temperature: 230°C, relaxation ratio: 0.93×0.95 (MD×TD)) to obtain a biaxially stretched SPS film with a thickness of 50 μm.

[0180] Production Example C (for Example 32) After obtaining an unstretched SPS sheet with a thickness of 500 μm, it was subjected to simultaneous biaxial stretching (temperature: 110°C, stretch ratio: 3.3×3.4 (MD×TD), stretching speed: 500% / min), and then subjected to relaxation heat treatment in a thermal drying oven (temperature: 230°C, relaxation ratio: 0.97×1.00 (MD×TD)) to obtain a biaxially stretched SPS film with a thickness of 50 μm.

[0181] Production Example D (for Example 33) After obtaining an unstretched SPS sheet with a thickness of 500 μm, it was subjected to sequential biaxial stretching (temperature: 90°C, stretching ratio: 3.3 × 3.3 (MD × TD), stretching speed: 100% / min). Then, it was subjected to relaxation heat treatment in a thermal drying oven (temperature: 230°C, relaxation ratio: 1.00 × 0.95 (MD × TD)) to obtain a biaxially stretched SPS film with a thickness of 50 μm.

[0182] ·Production example E (for comparative example 11) After obtaining an unstretched SPS sheet with a thickness of 500 μm, it was subjected to simultaneous biaxial stretching (temperature: 135°C, stretch ratio: 3.3×3.4 (MD×TD), stretching speed: 500% / min), and then subjected to relaxation heat treatment in a thermal drying oven (temperature: 230°C, relaxation ratio: 0.93×0.95 (MD×TD)) to obtain a biaxially stretched SPS film with a thickness of 50 μm.

[0183] ·Production example F (for comparative example 12) After obtaining an unstretched SPS sheet with a thickness of 500 μm, it was uniaxially stretched (temperature: 110°C, stretch ratio: 4.0×1.0 (MD×TD), stretching speed: 500% / min), and then subjected to a relaxation heat treatment in a thermal drying oven (temperature: 230°C, relaxation ratio: 0.97×1.00 (MD×TD)) to obtain a biaxially stretched SPS film with a thickness of 50 μm.

[0184] ·Manufacturing example G (for comparative example 13) After obtaining an unstretched SPS sheet with a thickness of 500 μm, it was subjected to sequential biaxial stretching (temperature: 110°C, stretch ratio: 3.3×3.3 (MD×TD), stretching speed: 500% / min), and then to relaxation heat treatment in a thermal drying oven (temperature: 230°C, relaxation ratio: 0.97×1.00 (MD×TD)), to obtain a biaxially stretched SPS film with a thickness of 50 μm.

[0185] <Method of manufacturing adhesive composition> An adhesive composition for use in the adhesive layer (ii) of the present invention was manufactured. The above-mentioned various components, namely, the styrene-based elastomer (a) and the curing agent (b), or the oligophenylene ether (c) and the acid-modified olefin (d), were blended and mixed to obtain a composition. More specifically, the compounds (a) to (d) and methyl ethyl ketone / toluene = 80 / 20 (vol%) were adjusted to 488 parts by mass (solid concentration 20 mass%), and the composition was prepared by applying varnish and drying.

[0186] <Manufacturing method and lamination of adhesive sheet> A varnish made of the adhesive composition was applied to a 50 μm-thick release PET film with a thickness of 25 μm (Examples 1-29, Comparative Examples 1-10) or 7.5 μm (Examples 30-33, Comparative Examples 11-13) using an applicator, and then cured in a hot air circulation dryer at a temperature of 130° C. for 5 minutes. The adhesive sheet thus obtained was used to bond onto an SPS resin sheet or film, and after the release PET film was peeled off, copper foil was used as the metal layer (iii) and bonded onto the adhesive sheet.

[0187] <Hot press conditions for laminate> A laminate was manufactured using the adhesive sheet and the heat-treated sheet obtained by the above manufacturing method. Specifically, a metal layer (copper foil layer) / adhesive sheet / heat-treated sheet / adhesive sheet / metal layer (copper foil layer) were laminated in this order, sandwiched between commercially available polyimide films (Ube Industries, Ltd., Upilex), then sandwiched further between silicone sheets (Chukoh Chemical Industries, Ltd., MSF-100, thickness: 100 μm), placed between SUS plates with a thickness of 2 mm, and compressed and heated (cured) with a hydraulic hand press (temperature: 180 ° C, time: 1 hour, under vacuum conditions, pressure: 2.0 MPa), and the obtained laminate was subjected to humidity conditioning treatment for 24 hours in an environment of 23 ° C × 50% RH, removing the influence of humidity, and obtaining a sample with little variation due to external factors.

[0188] In the following paragraphs, the SPS resin sheet or film used in the resin layer (i) was subjected to physical property evaluations 1 to 5, the adhesive sheet was subjected to physical property evaluation 6, and the laminate was subjected to physical property evaluations 7 to 10. Since the physical properties of the SPS resin sheet or film and the resin layer (i) are the same, the physical properties of the resin layer (i) alone may be taken out of the laminate and evaluated. Also, since the physical properties of the cured product of the adhesive sheet (adhesive composition) and the adhesive layer (ii) are the same, the physical properties of the adhesive layer (ii) alone may be taken out of the laminate and evaluated. Also, the metal layer (iii) may be taken out of the laminate and measured.

[0189] <Evaluation method> [Evaluation of heat-treated sheets / biaxially stretched films] 1. Dielectric properties The heat-treated sheet or biaxially stretched film was cut to prepare rectangular test pieces with dimensions of 3 mm in MD and 80 mm in TD. The dielectric properties of the test pieces at a frequency of 10 GHz (relative dielectric constant: Dk(ε)) were measured under a test environment of 23°C temperature and 50% relative humidity. c) / dielectric tangent: Df(tan δ)) was measured five times in total, and the average value was calculated (based on JIS C2565-1992). The measurement equipment used was the Anritsu MS46122B network analyzer and an AET cavity resonator. Those with a relative dielectric constant (Dk) of 3 or less were rated as passing (○), and those with a dielectric constant of more than 3 were rated as failing (×). In addition, those with a dielectric tangent (Df) of 0.002 or less were rated as passing (○), and those with a dielectric constant of more than 0.002 were rated as failing (×).

[0190] 2. Coefficient of linear expansion (TMA) The heat-treated sheet or biaxially stretched film was cut to prepare rectangular test pieces with a width of 3 mm and a length of 25 mm in the MD direction (test pieces with the lengthwise direction being the MD direction) and TD direction (test pieces with the lengthwise direction being the TD direction), respectively. The linear expansion coefficient of each test piece in the MD direction and TD direction obtained was measured five times, and the average value was calculated (in accordance with JIS K7197-2012). The measurement was performed using a TMA7100 manufactured by Hitachi High-Tech Science Co., Ltd. under a load of 2 gf / mm. The measurement results were read in the temperature range of 23°C to 80°C, and a linear expansion coefficient of 10 ppm or more and 80 ppm or less was considered to have passed.

[0191] 3. Solder heat resistance test The heat-treated sheet or biaxially stretched film was cut to prepare test pieces of 50 mm in MD × 50 mm in TD. The test pieces were then floated in a solder bath heated to 260°C for 120 seconds, and the appearance was visually observed. Those that showed no deformation or swelling in appearance were rated as ◎, those that showed no significant deformation or swelling in appearance were rated as pass (〇), those that showed partial wrinkles were rated as pass (△), and those that showed significant deformation or abnormal swelling in appearance were rated as fail (×).

[0192] 4. Surface roughness (Rz) The sheet or biaxially stretched film before heat treatment was cut to prepare a test piece of 100 mm in MD × 100 mm in TD. Then, using a surface roughness measuring instrument (SJ-310) in an atmosphere of room temperature: 25°C × humidity: 50% RH, the ten-point average roughness Rz of the touch roll surface was measured five times in each of the MD and TD directions, and the average value of a total of 10 points was calculated.

[0193] 5. Dimensional change rate The heat-treated sheet or biaxially stretched film was cut to prepare a rectangular test piece with dimensions of 180 mm in MD and 130 mm in TD. Straight lines were drawn on the surface of the test piece to form a square with dimensions of 120 mm in length and 70 mm in MD x TD, parallel to the MD and TD directions, and intersecting at the midpoint. The lengths of the straight lines in the MD and TD directions of this test piece were measured. Next, the specimen was left suspended with one corner supported for 30 minutes in a hot air circulating oven set to an atmosphere of 150°C, and then removed from the oven and left to cool for 24 hours in an environment of temperature: 23°C / relative humidity: 50%RH to remove the influence of moisture content. Then, the straight lengths in the MD / TD directions were measured, and the amount of change from the length measured before the 150°C / 30-minute test was calculated, and the thermal shrinkage was calculated as the ratio of the amount of change to each length before the test. If the thermal shrinkage value is positive, it means that the specimen has shrunk. If the absolute value of the thermal shrinkage is 0.4% or less, it is considered to have passed (○), and if it exceeds 0.4%, it is considered to have failed (×).

[0194] [Evaluation of adhesive sheets] 6. Dynamic viscoelasticity test (storage modulus) The adhesive composition described below was applied to a Teflon (registered trademark) sheet using an applicator so that the thickness after drying would be 15 to 25 μm, and dried at 130° C. for 5 minutes. The adhesive film (B stage product) obtained in this manner was further dried at 180° C. for 1 hour. The obtained adhesive sheet was peeled off from the Teflon (registered trademark) sheet, and the adhesive sheet alone was subjected to a dynamic viscoelasticity test under an atmosphere of temperature: 25° C. / relative humidity: 50% RH. The equipment used was DVA-225 manufactured by IT Measurement and Control Co., Ltd., and the temperature was raised from -50° C. to 300° C. at a heating rate of 4° C. / min using a tester with a width of 4 mm and a length of 15 mm, and the viscoelasticity was measured at a vibration frequency of 10 GHz. From the obtained viscoelasticity curve, the storage modulus was calculated at room temperature.

[0195] [Evaluation of Laminate (Resin Layer (i) / Adhesive Layer (ii) / Metal Layer (iii))] The measurements of "7. Sheet adhesion" to "10. Transmission loss" below were carried out by preparing a five-layer laminate sample of metal layer (iii) / adhesive layer (ii) / resin layer (i) / adhesive layer (ii) / metal layer (iii).

[0196] 7. Sheet bonding ability The adhesive film (B stage product) obtained by the same method as described above was laminated in the order of 18 μm thick rolled copper foil (I-IV) / adhesive sheet / heat-treated sheet / adhesive sheet / 18 μm thick rolled copper foil (I-IV) and the layers were bonded together to produce a laminate. The bonding was performed under vacuum conditions at 180°C for 60 minutes with a pressure of 2.0 MPa, with the roughened surface of the rolled copper foil in contact with the adhesive layer. The appearance of the obtained laminate was evaluated. In this case, the appearance without wrinkles or streaks was evaluated as (○), and the appearance with wrinkles or streaks was evaluated as (△).

[0197] 8.Peel strength (adhesiveness) A laminate sample was prepared in the same manner as above. The peel strength was measured by subjecting the laminate sample to a tensile test at a tensile speed of 50 mm / min in an atmosphere of temperature: 23°C / relative humidity: 50% RH, and measuring the peel strength at the interface between the resin layer (i) and the adhesive layer (ii). This test indicates the adhesive strength at room temperature.

[0198] 9. Solder heat resistance test A laminate sample was prepared in the same manner as above, and a sample piece (cut from the laminate) measuring 50 mm in the MD direction and 50 mm in the TD direction was aged for two days at a temperature of 23°C and a relative humidity of 50%RH. The laminate was then immersed in a solder bath heated to 260°C for 120 seconds, and visually observed for the degree of deformation and the presence of abnormalities in appearance such as swelling. Those that showed no deformation or swelling in appearance were rated as ◎, those that showed no significant deformation or swelling in appearance were rated as pass (〇), those that showed partial wrinkles were rated as pass (△), and those that showed significant deformation or abnormalities in appearance such as swelling were rated as fail (×).

[0199] 10. Transmission Loss A sample of the laminate was prepared in the same manner as above, and the transmission loss was evaluated using a vector network analyzer (manufactured by Anritsu). A microstrip line with an impedance of 50 Ω was prepared on one side of the metal layer (iii), and the other side was used as a ground layer. Then, both ends of the microstrip line and the ground layer were connected to a measuring device, and the transmission amount of the incident wave to the microstrip line was measured up to a frequency of 40 GHz under conditions of temperature = 23 ° C and humidity = 50% RH, and the transmission loss was calculated. The transmission loss was calculated using the transmission amount at a frequency of 40 GHz from the formula: transmission loss (dB / 100 mm) = transmission amount (dB) / line length (100 mm), and the absolute value was taken as the transmission loss. This allows the transmission loss of the laminate of "resin layer (i) / adhesive layer (ii) / metal layer (iii)" to be measured.

[0200] (Examples 1 to 29, Examples 30 to 34) In addition to Examples 1 to 29, laminates prepared in Production Examples A to C are used as Examples 30 to 33. In Examples 1 to 29, a non-stretched sheet is used as the resin layer (i), and by containing the above-mentioned (A) component, or the (A) to (C) components, (D) component, and (E) components in a predetermined amount, the required physical properties can be satisfied, and a performance with excellent overall balance is exhibited. In addition, although the biaxially stretched films described in Examples 30 to 33 prepared in Production Examples A to D have some issues with the appearance of the laminate, they can satisfy the minimum required physical properties, and exhibit a performance with excellent balance, second only to the non-stretched sheet. In addition, the adhesive layer (ii) described in Examples 1 to 29 contains the (a) and (b) or (c) to (d) components in a predetermined amount, and the laminate with the non-stretched sheet or the biaxially stretched film has excellent peel strength and solder heat resistance. Furthermore, the laminates in which the resin layer (i) and the metal layer (iii) described in Examples 1 to 33 are bonded together using the adhesive layer (ii) have excellent dielectric properties, and the surface roughness Rz of the resin layer (i) and the metal layer (iii) can be reduced, so that the path of the electric signal at the interface between the layers can be shortened, and therefore, the laminates exhibit excellent transmission loss. The results of the examples are shown in Tables 1 to 5.

[0201] [Table 1]

[0202] [Table 2]

[0203] [Table 3]

[0204] [Table 4]

[0205] [Table 5]

[0206] (Comparative Examples 1 to 10, Comparative Examples 11 to 13) In Comparative Examples 1 to 10, a non-stretched sheet is used as the resin layer (i), but the (A) component, or the (A) to (C) components, (D) component, and (E) components are added in excess or insufficiently, and therefore the required physical properties of the resin sheet cannot be met. In addition, the laminates made of biaxially stretched films in Comparative Examples 11 to 13 do not satisfy the CTE ratio in the MD / TD direction of the film used as the resin layer (i) (MD / TD ratio) or the dimensional change rate during heat treatment, and therefore cannot satisfy the required physical properties of the laminate. In addition, the adhesive layer (ii) containing a predetermined amount of the (a) and (b) or (c) to (d) components, and the laminate in which the resin layer (i) and the metal layer (iii) are bonded together using the adhesive layer (ii) cannot satisfy the required properties in terms of peel strength, solder heat resistance, and transmission loss. The results are shown in Tables 6 and 7. In Tables 6 and 7, "-" indicates that the adhesive sheet was insufficiently cured or the adhesive sheet itself was too soft, and therefore could not be evaluated.

[0207] [Table 6]

[0208] [Table 7] [Industrial Applicability]

[0209] As is clear from the above description, according to the present invention, the electronic circuit board laminate described in the examples has excellent dielectric properties, linear expansion coefficient, and solder heat resistance, as well as peel strength and transmission loss, and is therefore expected to be used in high-frequency circuit boards. Specifically, it is expected that the sheet molded body of the present invention can be used in electronic components and antenna components for communication devices that require 5G.

Claims

1. A laminate in which a resin layer (i), an adhesive layer (ii), and a metal layer (iii) are laminated in this order, The resin layer (i) contains a styrene-based polymer (A) having a syndiotactic structure, The resin layer (i) has a linear expansion coefficient in a machine direction (MD) and a transverse direction (TD) of 10 to 80 ppm / °C, and the MD / TD ratio is in the range of 0.6 to 1.4; The peel strength between the resin layer (i) and the adhesive layer (ii) is 0.3 kN / m or more; The laminate has an absolute value of transmission loss of 5.0 dB / 100 mm or less at a frequency of 40 GHz.

2. 2. The laminate according to claim 1, wherein the surface roughness Rz of the resin layer (i) is 0.1 μm or more and 6.0 μm or less.

3. 2. The laminate according to claim 1, wherein the surface roughness Rz of the resin layer (i) is 0.1 μm or more and 3.0 μm or less.

4. The laminate according to claim 1 or 2, wherein the adhesive layer (ii) contains a styrene-based elastomer and a curing agent.

5. The laminate according to claim 1 or 2, wherein the surface roughness Rz of the metal layer (iii) is 0.1 μm or more and 7.0 μm or less.

6. The laminate according to claim 1 or 2, wherein the resin layer (i) further contains a fibrous filler (C).

7. The laminate according to claim 1 or 2, wherein the resin layer (i) further contains a non-fibrous filler (D).

8. 3. The laminate according to claim 1, wherein the resin layer (i) further contains a fibrous filler (C) and a non-fibrous filler (D).

9. The resin layer (i) further contains a fibrous filler (C) and a non-fibrous filler (D), 3. The laminate according to claim 1, comprising 1 to 50 parts by mass of the fibrous filler (C) based on 100 parts by mass of the styrene-based polymer (A) having a syndiotactic structure.

10. The laminate according to claim 1 or 2, which is used for an electronic circuit board.

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