Laminate and metal-clad laminate having said laminate

Abstract

To provide a metal-clad laminate (for example, copper-clad laminate (CCL)) that has good electrical properties (dielectric properties) compatible with 5G, has excellent adhesion (adhesion) between a base film (laminate) and a metal film, has excellent dimensional stability, and is suppressed from curling. The present invention also provides a laminate for a printed wiring board, which is used to form the metal-clad laminate. [Solution] A laminate comprising a low-CTE resin film having a coefficient of linear thermal expansion (CTE) of 50 ppm / °C or less and having no melting point below 300°C, and a resin film (SPS resin film) made of a styrene-based polymer (SPS) having a syndiotactic structure laminated on both sides of the low-CTE resin film.

Description

[Technical Field]

[0001] The present invention relates to a laminate and a metal-clad laminate having the laminate. [Background technology]

[0002] In recent years, as communication speeds and capacity have increased in communication devices such as smartphones, the circuit boards used in these devices are required to have low loss in electrical signals, finer pitch circuit patterns, and more precise and fine circuit formation. Metal-clad laminates, which are the main material of circuit boards, are metal-clad laminates (e.g., copper-clad laminates (CCL)) in which a metal film is laminated on the surface of a base film made of insulating resin, and the like, are also required to have performance similar to that of the above-mentioned circuit boards. Various improved metal-clad laminates and laminates for use in the metal-clad laminates have been proposed (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-75030 Summary of the Invention [Problem to be solved by the invention]

[0004] Meanwhile, with the full-scale introduction of next-generation mobile communication systems such as 5G, there is a demand for metal-clad laminates that use substrate films made of low-dielectric materials. However, since many low-dielectric substrate films have a large CTE, it has been found that when a metal-clad laminate is formed using a low-dielectric substrate film, the film shrinks significantly, resulting in poor dimensional stability of the metal-clad laminate and problems such as deformation and curling of the metal-clad laminate.On the other hand, even if dimensional stability and curling due to film shrinkage are not a problem, it has been found that the adhesion (adhesion) between the substrate film and the metal film may be poor. For example, the copper-clad laminate (CCL) described in Patent Document 1 above was not sufficient from the viewpoint of providing a copper-clad laminate (CCL) that has good electrical properties (dielectric properties) compatible with 5G, excellent adhesion (tightness) between the substrate film and the metal film, excellent dimensional stability, and suppressed curling. Furthermore, since many substrate films with low CTEs, which are used to reduce film shrinkage and improve dimensional stability, have poor dielectric properties, forming a metal-clad laminate using a low-CTE substrate film creates the problem of not being able to obtain a metal-clad laminate with excellent dielectric properties.

[0005] The present invention has been made in view of the above circumstances, and aims to provide a metal-clad laminate (e.g., a copper-clad laminate (CCL)) that has good electrical properties (dielectric properties) compatible with 5G, excellent adhesion (tightness) between the substrate film (laminate) and the metal film, excellent dimensional stability, and suppressed curling. Another object of the present invention is to provide a laminate for a printed wiring board, which is used to form the metal-clad laminate. [Means for solving the problem]

[0006] As a result of extensive research into solving the above-mentioned problems, the present inventors have found that the above-mentioned problems can be solved by a laminate in which a resin film (SPS resin film) made of a styrene-based polymer (SPS) having a syndiotactic structure is disposed on both sides of a low-CTE resin film having a low coefficient of linear thermal expansion (CTE) and a melting point of 300°C or less, and have thus completed the present invention.

[0007] The present invention includes the following aspects. [1] A low-CTE resin film having a coefficient of linear thermal expansion (CTE) of 50 ppm / ℃ or less and a melting point of 300℃ or less; A laminate obtained by laminating a resin film (SPS resin film) made of a styrene-based polymer (SPS) having a syndiotactic structure on both sides of the low CTE resin film. [2] The laminate according to [1], wherein the low CTE resin film is a film made of a resin selected from polyimide (PI), liquid crystal polymer (LCP), and stretched polyether ether ketone (stretched PEEK). [3] The laminate according to [1] or [2], wherein the melting point of the SPS resin film is 250°C or higher. [4] The laminate according to any one of [1] to [3], wherein the SPS resin film has a relative dielectric constant of 2.6 or less. [5] The laminate according to any one of [1] to [4], wherein the SPS resin film has a dielectric loss tangent of less than 0.0020. [6] The laminate according to any one of [1] to [5], wherein the SPS resin film has a water absorption rate of 0.2% or less. [7] The laminate according to any one of [1] to [6], wherein the low CTE resin film has a water absorption rate of 2.5% or less. [8] The laminate according to any one of [1] to [7], wherein the ratio of the thickness of the SPS resin film to the thickness of the low CTE resin film (the SPS resin film:the low CTE resin film) is 1:10 to 10:1. [9] The laminate according to any one of [1] to [8], wherein the SPS resin film has a relative crystallinity of 25% to 85%.

[10] The laminate according to any one of [1] to [9], wherein the surface of the low CTE resin film and / or the SPS resin film has been subjected to a surface treatment selected from a corona treatment, a plasma treatment, and an ultraviolet treatment.

[11] The laminate according to any one of [1] to [9], wherein the surface of the low CTE resin film and / or the SPS resin film has been subjected to a surface treatment with a coupling agent.

[12] A metal-clad laminate obtained by laminating a metal film on one or both sides of the laminate according to any one of [1] to

[11] .

[13] A method for producing a laminate according to any one of [1] to

[11] , comprising arranging the SPS resin film, the low CTE resin film, and the SPS resin film in this order, and thermocompression bonding the resulting laminate.

[14] The method for producing a laminate according to

[13] , wherein the thermocompression bonding is carried out at a temperature in the range of −10° C. to 30° C. relative to the melting point of the SPS resin film.

[15] A method for producing a metal-clad laminate according to

[12] , comprising arranging a metal film on one or both sides of the laminate produced by

[13] or

[14] , and thermocompression bonding the laminate to obtain the metal-clad laminate.

[16] A method for producing a metal-clad laminate according to

[12] , A metal film, the SPS resin film, the low CTE resin film, and the SPS resin film are arranged in this order and then thermally compressed together, or A method for producing a metal-clad laminate, comprising arranging a metal film, the SPS resin film, the low CTE resin film, the SPS resin film, and a metal film in this order, and then thermocompression bonding the resulting laminate.

[17] The method for producing a metal-clad laminate according to

[15] or

[16] , wherein the thermocompression bonding is carried out at a temperature in the range of −10° C. to 30° C. relative to the melting point of the SPS resin film. [Effects of the Invention]

[0008] According to the present invention, it is possible to provide a metal-clad laminate (e.g., a copper-clad laminate (CCL)) that has good electrical properties (dielectric properties) compatible with 5G, has excellent adhesion (tightness) between the substrate film (laminate) and the metal film, has excellent dimensional stability, and is suppressed from curling. Furthermore, according to the present invention, it is possible to provide a laminate for a printed wiring board, which is used to form the above-mentioned metal-clad laminate. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a cross-sectional view showing an example of the configuration of a laminate of the present invention. [Figure 2] 1 is a cross-sectional view showing an example of the configuration of a metal-clad laminate of the present invention.

[0010] The laminate for printed wiring boards of the present invention and the metal-clad laminate of the present invention formed using the laminate will be described in detail below, but the description of the constituent elements described below is an example of one embodiment of the present invention and is not limited to these contents. The following definitions of terms apply throughout the specification and claims. The melting point in the present invention can be measured in accordance with JIS K 7121. Specifically, about 5 mg of a measurement sample is weighed out from a melt-extrusion molded resin film, and the melting point is measured using a differential scanning calorimeter (SII Technologies, Inc.: high-sensitivity differential scanning calorimeter X-DSC 7000) at a heating rate of 10°C / min over a measurement temperature range of 20°C to 380°C. The film thickness of a resin film, metal film (metal foil film), etc. is determined by observing the cross section of the object to be measured using a microscope, measuring the thickness at five points, and averaging the measured values.

[0011] (Laminate) The laminate is a laminate for printed wiring boards and can be used to produce metal-clad laminates (copper-clad laminates (CCL)). The laminate is made up of three layers of resin films laminated together. The laminate is formed by laminating a low-CTE resin film having a coefficient of linear thermal expansion (CTE) (CTE from 20°C to 140°C) of 50 ppm / °C or less, and a resin film (hereinafter also referred to as "SPS resin film") made of a styrene-based polymer (SPS) having a syndiotactic structure on both sides of the low-CTE resin film. The low CTE resin film does not have a melting point below 300°C. In this specification, the coefficient of linear thermal expansion (CTE) is also referred to as the thermal expansion coefficient, the linear thermal expansion rate, or the thermal expansion rate.

[0012] <Layer structure of laminate> FIG. 1 is a cross-sectional view showing an example of the structure of the laminate of the present invention. The laminate 11 has an SPS resin film 13, a low CTE resin film 12, and an SPS resin film 14 laminated in this order.

[0013] <Low CTE resin film> The low-CTE resin film is disposed in the middle of a laminate formed by laminating three resin films, and has a linear thermal expansion coefficient (CTE) (CTE from 20°C to 140°C) of 50 ppm / °C or less. Additionally, the low CTE resin film does not have a melting point below 300°C. By disposing such a low CTE resin film in the center of the laminate, it is possible to effectively prevent deterioration of the dimensional stability of the laminate and curling of the laminate.

[0014] The coefficient of linear thermal expansion (CTE) (CTE at 20°C to 140°C) of the low-CTE resin film is preferably 5 to 50 ppm / °C, and more preferably 10 to 30 ppm / °C, because a value closer to the CTE of the metal film (e.g., copper film) to be laminated as a metal-clad laminate (e.g., copper-clad laminate (CCL)) provides better curl suppression and dimensional stability.

[0015] The coefficient of linear expansion (CTE) can be measured using a thermomechanical analyzer (TMA) in accordance with JIS K 7197: 1991. For example, it can be measured in tension mode using a thermomechanical analyzer (product name: SII / / SS7100, manufactured by Hitachi High-Tech Science Corporation) under conditions of a load of 50 mN and a heating rate of 5°C / min in the range of 10°C to 200°C, and the coefficient of linear expansion (ppm / °C) can be calculated from the slope in the range of 20°C to 140°C.

[0016] Since the low CTE resin film does not have a melting point below 300°C, it is preferably a film made of a thermosetting resin or a thermoplastic resin with a melting point higher than 300°C, and is preferably a film made of a resin selected from, for example, polyimide (PI), liquid crystal polymer (LCP), and oriented polyether ether ketone (oriented PEEK). When the low-CTE resin film is made of a thermoplastic resin and has a melting point higher than 300° C., it is more preferable in the present invention that the low-CTE resin film does not melt at a temperature obtained by adding 30° C. to the melting point of the SPS resin film. In other words, it is more preferable in the present invention that the melting point of the low-CTE resin film is higher than the temperature obtained by adding 30° C. to the melting point of the SPS resin film. Furthermore, in the present invention, a highly flame-retardant resin is selected as the resin for forming the low CTE resin film, and the low CTE resin film is made a resin film with high flame retardancy, thereby making it possible to obtain a laminate with improved flame retardancy.

[0017] The low-CTE resin film may contain fillers and various additives to impart various functions to the resin film, such as strength, insulation properties, heat resistance, adjustment of the coefficient of linear thermal expansion (CTE), etc. Examples of additives include antioxidants, light stabilizers, ultraviolet absorbers, crystal nucleating agents (nucleating agents), plasticizers, and filler dispersants.

[0018] <<Filler>> Examples of fillers include inorganic fillers and organic fillers, which can be used alone or in combination.

[0019] Examples of inorganic fillers include mica, talc, boron nitride, magnesium oxide, silica, diatomaceous earth, titanium oxide, zinc oxide, etc. Among these, inorganic fillers such as mica, talc, boron nitride, magnesium oxide, and silica are preferred. The organic filler is not particularly limited, but examples thereof include organic particles such as polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polystyrene, polyamide, polycarbonate, polyimide, polyether ketone, polyether ether ketone, polymethyl methacrylate, liquid crystal polymer, and polytetrafluoroethylene. The inorganic filler and the organic filler may be selected from the above and used alone or in combination of two or more. When two or more types are combined, the combination may be an inorganic filler and an organic filler.

[0020] <<Characteristics of low CTE resin film>> The film thickness of the low CTE resin film is not particularly limited and can be appropriately selected depending on the purpose, but is preferably 5 μm to 150 μm, more preferably 10 μm to 80 μm, and even more preferably 12 μm to 60 μm. If the film is too thick, the dielectric properties may deteriorate, and if the film is too thin, curling suppression and dimensional stability may become unstable.

[0021] The surface roughness (Rz) of the low CTE resin film is not particularly limited and can be selected appropriately depending on the purpose, but is preferably 1 to 10 μm, for example. If the surface roughness is too small, the film will not be able to be wound up properly, while if it is too large, problems such as unstable adhesive strength and the inclusion of air bubbles will occur when the film is laminated to an SPS resin film. In this specification, surface roughness (Rz) refers to the ten-point average roughness of the film surface. The ten-point average roughness RzJIS can be determined based on JIS B 0601:2013 (ISO 4287:1997 Amd.1:2009). In this specification, the surface roughness of each layer determined by the ten-point average roughness RzJIS is referred to as "surface roughness (Rz)."

[0022] [Measurement of ten-point average roughness RzJIS] The ten-point average roughness RzJIS (μm) of the sheet surface is obtained by measuring the roughness curve of the test piece using a laser microscope, measuring 10 samples from each roughness curve based on JIS B 0601:2013 (ISO 4287:1997 Amd.1:2009), and calculating the average value.

[0023] The relative dielectric constant and dielectric dissipation factor of the low CTE resin film are not particularly limited and can be selected appropriately depending on the purpose, but for the purpose of reducing transmission loss of electrical signals, it is preferable that the relative dielectric constant is 3.5 or less and the dielectric dissipation factor is 0.025 or less. The low CTE resin film preferably has a low relative dielectric constant, but within a practically possible range, the dielectric constant is preferably 2.5 to 3.5, more preferably 3.0 to 3.5. The low CTE resin film also has a dielectric loss tangent of preferably 0.001 to 0.025, more preferably 0.001 to 0.01, and even more preferably 0.001 to 0.008.

[0024] [Dielectric constant and dielectric loss tangent] The relative dielectric constant and dielectric loss tangent of the resin film can be measured by the open resonator method using a network analyzer MS46122B (manufactured by Anritsu) and an open resonator Fabry-Perot DPS-03 (manufactured by KEYCOM) under conditions of a temperature of 23°C, humidity of 50%, and a frequency of 28 GHz.

[0025] Since the dielectric properties of the substrate deteriorate significantly when the substrate absorbs moisture, the water absorption rate of the low CTE resin film is, for example, preferably 0 to 2.5%, more preferably 0.01 to 2.0%, even more preferably 0.03 to 1.5%, and particularly preferably 0.05 to 1.2%.

[0026] [Water absorption rate] The water absorption rate can be determined in accordance with JIS K7209A method by measuring the sample by immersing it in water at 23°C for 24 hours. The water absorption rate is calculated from the change in mass before and after immersion in water. Water absorption rate = ((mass after 24-hour moisture test - mass before test) / mass before test) x 100

[0027] The surface of the low CTE resin film is preferably subjected to any surface treatment selected from corona treatment, plasma treatment, and ultraviolet treatment for reasons such as improving adhesion. Also, the surface of the low CTE resin film may be surface-treated with a coupling agent for reasons such as improving adhesion. As the silane coupling agent, a known silane coupling agent can be used. For example, alkoxysilane or the like can be used.

[0028] <SPS resin film> The SPS resin film is disposed on both sides of the low CTE resin film. By providing such an SPS resin film, in combination with the above low CTE resin film, deterioration of the dimensional stability of the laminate and curling of the laminate can be effectively prevented. As described above, the SPS resin film refers to a resin film made of a syndiotactic styrene polymer (SPS) having a syndiotactic structure. The SPS resin film is formed using a syndiotactic styrene polymer or a resin composition containing the syndiotactic styrene polymer.

[0029] <<Syndiotactic styrene polymer (SPS) having a syndiotactic structure>> The syndiotactic structure in a styrene polymer having a syndiotactic structure 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 its tacticity is quantified by nuclear magnetic resonance spectroscopy using a carbon isotope (C-NMR). Tacticity measured by C-NMR can be expressed by the proportion of consecutive structural units present, for example, two units are dyads, three units are triads, and five units are pentads. The styrene polymer having a syndiotactic structure referred to in the present invention generally refers to polystyrene, poly(alkylstyrene), poly(arylstyrene), poly(halogenated styrene), poly(halogenated alkylstyrene), poly(alkoxystyrene), poly(vinyl benzoate ester), hydrogenated polymers thereof, mixtures thereof, or copolymers containing these as the main component, having a syndiotacticity of 75% or more, preferably 85% or more, in racemic dyads, or 30% or more, preferably 50% or more, in racemic pentads. Here, examples of poly(alkylstyrenes) include poly(methylstyrene), poly(ethylstyrene), poly(isopropylstyrene), poly(tertiarybutylstyrene), etc.; examples of poly(arylstyrenes) include poly(phenylstyrene), poly(vinylnaphthalene), poly(vinylstyrene), etc.; examples of poly(halogenated styrenes) include poly(chlorostyrene), poly(bromostyrene), poly(fluorostyrene), etc.; examples of poly(halogenated alkylstyrenes) include poly(chloromethylstyrene), etc.; and examples of poly(alkoxystyrenes) include poly(methoxystyrene), poly(ethoxystyrene), etc.

[0030] Among these, preferred styrene-based polymers include polystyrene, poly(p-methylstyrene), poly(m-methylstyrene), poly(p-tertiarybutylstyrene), poly(p-chlorostyrene), poly(m-chlorostyrene), poly(p-fluorostyrene), hydrogenated polystyrene, and copolymers containing these structural units.

[0031] Styrenic polymers 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 alkylstyrenes) 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.

[0032] Among these styrene polymers having a syndiotactic structure, in the present invention, those having a tacticity of 70% or more in racemic pentad and a weight average molecular weight of 50,000 to 800,000 are particularly preferred from the standpoint of heat resistance and mechanical strength.

[0033] <<Resin composition containing syndiotactic polystyrene>> The SPS resin film according to the present invention is not only a resin film formed using the above-mentioned syndiotactic polystyrene (SPS), but also a resin film formed using a resin composition containing syndiotactic polystyrene. This resin composition must contain (a) syndiotactic polystyrene as a resin component, but may also contain (b) a rubber-like elastomer and / or a thermoplastic resin other than a styrene-based polymer having a syndiotactic structure in order to improve mechanical properties such as strength. Furthermore, in order to impart various functions to the resin film, such as strength, insulation, heat resistance, and adjustment of the coefficient of linear thermal expansion (CTE), fillers and various additives may be contained within a range that does not impair the object of the present invention. Fillers and various additives are as explained above in the section <Low CTE resin film>. In addition to the additives described above, for example, antiblocking agents, antistatic agents, process oils, release agents, compatibilizers, flame retardants, flame retardant assistants, pigments, inorganic fillers, etc. In the present invention, there is no need to make a clear distinction between fillers and various additives, and for example, some fall under both fillers and inorganic fillers, and some fall under both antiblocking agents and inorganic fillers.However, in the present invention, any substance that can be used as any of the above-mentioned fillers and various additives can be contained in the resin composition.

[0034] The components may be kneaded by various methods, such as blending and melt-kneading them at any stage in the syndiotactic polystyrene production process, or blending and melt-kneading the components constituting the composition. Each component contained in the resin composition containing syndiotactic polystyrene will be described below.

[0035] <<<Rubber-like elastic body>>> Specific examples of the rubber-like elastic material include natural rubber, polybutadiene, polyisoprene, polyisobutylene, neoprene, polysulfide rubber, thiokol rubber, acrylic rubber, urethane rubber, silicone rubber, epichlorohydrin rubber, styrene-butadiene block copolymer (SBR), hydrogenated styrene-butadiene block copolymer (SEB), styrene-butadiene-styrene block copolymer (SBS), hydrogenated styrene-butadiene-styrene block copolymer (SEBS), styrene-isoprene block copolymer (SIR), hydrogenated styrene-isoprene block copolymer (SEP), styrene-isoprene-styrene block copolymer (SIS), hydrogenated styrene-isoprene-styrene block copolymer (SEPS), and ethylene propylene rubber (EPM). ), ethylene propylene diene rubber (EPDM), linear low-density polyethylene elastomers and other olefin-based rubbers, or core-shell type particulate elastomers such as 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 thereof.

[0036] Among these rubber-like elastic materials, hydrogenated styrene-butadiene-styrene block copolymer (SEBS) is preferred in the present invention from the viewpoint of heat resistance and dielectric properties.

[0037] <<<Thermoplastic resins other than syndiotactic polystyrene>>> Thermoplastic resins other than syndiotactic polystyrene include linear high-density polyethylene, linear low-density polyethylene, high-pressure low-density polyethylene, isotactic polypropylene, syndiotactic polypropylene, block polypropylene, random polypropylene, polybutene, 1,2-polybutadiene, 4-methylpentene, cyclic polyolefins and their copolymers, as well as atactic polystyrene, isotactic polystyrene, HIPS, ABS, AS, styrene-methacrylic acid copolymer, styrene-methacrylic acid alkyl ester copolymer, styrene-methacrylic acid ... Any known resin may be selected and used, including polystyrene resins such as acrylic acid-glycidyl ester copolymer, styrene-acrylic acid copolymer, styrene-acrylic acid-alkyl ester copolymer, styrene-maleic acid copolymer, and styrene-fumaric acid copolymer; polyester resins such as polycarbonate, polyethylene terephthalate, and polybutylene terephthalate; polyamide resins such as polyamide 6 and polyamide 6,6; fluorinated polyethylene resins such as polyphenylene ether, polyarylene sulfide, and poly-4-fluoroethylene (PTFE). Among these, polyolefins such as polyethylene and polypropylene, or polyphenylene ether, are preferred. These thermoplastic resins may be used singly or in combination of two or more.

[0038] <<<Various additives>>> Various additives such as those exemplified below can be added as long as they do not impede the object of the present invention.

[0039] [Anti-blocking agent (AB agent)] Examples of the anti-blocking agent include inorganic particles or organic particles such as those listed below. Examples of inorganic particles include oxides, hydroxides, sulfides, nitrides, halides, carbonates, sulfates, acetates, phosphates, phosphites, organic carboxylates, silicates, titanates, borates, and hydrated compounds thereof, composite compounds centered on these, and natural mineral particles of Group IA, IIA, IVA, VIA, VIIA, VIII, IB, IIB, IIIB, and IVB elements.

[0040] Specifically, the following may be used: Group IA element compounds such as lithium fluoride and borax (sodium borate hydrate); Group IIA element compounds such as magnesium carbonate, magnesium phosphate, magnesium oxide (magnesia), magnesium chloride, magnesium acetate, magnesium fluoride, magnesium titanate, magnesium silicate, magnesium silicate hydrate (talc), calcium carbonate, calcium phosphate, calcium phosphite, calcium sulfate (gypsum), calcium acetate, calcium terephthalate, calcium hydroxide, calcium silicate, calcium fluoride, calcium titanate, strontium titanate, barium carbonate, barium phosphate, barium sulfate, and barium sulfite; titanium dioxide (titania), titanium monoxide, titanium nitride, zirconium dioxide (zirconium dioxide), Group IB element compounds such as copper(I) iodide; Group IIB element compounds such as zinc oxide and zinc acetate; Group IIIB element compounds such as aluminum oxide (alumina), aluminum hydroxide, aluminum fluoride, and alumina silicate (alumina silicate, kaolin, and kaolinite); Group IVB element compounds such as silicon oxide (silica, silica gel), graphite, carbon, graphite, and glass; and particles of natural minerals such as karnalite, kainite, mica, and byronic acid.

[0041] Examples of organic particles include Teflon, melamine resin, styrene-divinylbenzene copolymer, acrylic resin, and their crosslinked materials.

[0042] [Antioxidants] The antioxidant can be selected from known antioxidants such as phosphorus-based, phenol-based, sulfur-based, etc. These antioxidants can be used alone or in combination of two or more.

[0043] [Nucleating agent] The nucleating agent can be arbitrarily selected from known nucleating agents such as metal salts of carboxylic acids such as aluminum di(pt-butylbenzoate), metal salts of phosphoric acids such as sodium methylenebis(2,4-di-t-butylphenol) acid phosphate, talc, phthalocyanine derivatives, etc. These nucleating agents can be used alone or in combination of two or more.

[0044] [Plasticizer] The plasticizer can be arbitrarily selected from known plasticizers such as polyethylene glycol, polyamide oligomer, ethylene bisstearamide, phthalate ester, polystyrene oligomer, polyethylene wax, silicone oil, etc. These plasticizers can be used alone or in combination of two or more.

[0045] [Release agent] The release agent can be arbitrarily selected from known agents such as polyethylene wax, silicone oil, long-chain carboxylic acid, metal salt of long-chain carboxylic acid, etc. These release agents can be used alone or in combination of two or more.

[0046] [Process oil] In the present invention, a process oil may be further blended. Process oils are broadly classified into paraffinic oils, naphthenic oils, and aromatic oils depending on the type of oil, with paraffinic oils being preferred. The kinematic viscosity of the process oil at 40°C is preferably 15 to 600 cs, more preferably 15 to 500 cs. These process oils may be used alone or in combination of two or more.

[0047] [Compatibilizer] The compatibilizer referred to in the present invention is blended to improve the affinity between syndiotactic polystyrene and the thermoplastic resin and / or rubber-like elastomer, thereby effectively compatibilizing them, and also to improve the affinity between syndiotactic polystyrene and the inorganic filler. Specific examples of the compatibilizer include polymers that have compatibility or affinity with syndiotactic polystyrene and have polar groups.

[0048] Here, the term "polymer having compatibility or affinity with syndiotactic polystyrene" refers to a polymer containing a chain exhibiting compatibility or affinity with syndiotactic polystyrene in the polymer chain. Examples of such polymers exhibiting compatibility or affinity include those having syndiotactic polystyrene, atactic polystyrene, isotactic polystyrene, styrene copolymers, polyphenylene ether, polyvinyl methyl ether, etc. as the main chain, block chain, or graft chain.

[0049] The polar group referred to here may be any group that improves adhesion to an inorganic filler, and specific examples thereof include an acid anhydride group, a carboxylic acid group, a carboxylic acid ester group, a carboxylic acid chloride group, a carboxylic acid amide group, a carboxylic acid salt group, a sulfonic acid group, a sulfonic acid ester group, a sulfonic acid chloride group, a sulfonic acid amide group, a sulfonic acid salt group, an epoxy group, an amino group, an imide group, and an oxazoline group.

[0050] This compatibilizer can be obtained by reacting the above polymer having compatibility or affinity with syndiotactic polystyrene with a modifier, which will be described later, in the presence or absence of a solvent or other resin. The modifier may be, for example, a compound containing an ethylenic double bond and a polar group in the same molecule. Specific examples include maleic anhydride, maleic acid, maleic acid esters, maleimide and its N-substituted derivatives, maleic acid derivatives such as maleates, fumaric acid, fumaric acid esters, fumaric acid derivatives such as fumarate, itaconic anhydride, itaconic acid, itaconic acid esters, itaconic acid derivatives such as itaconate, acrylic acid, acrylic acid esters, acrylic acid amides, acrylic acid derivatives such as acrylates, methacrylic acid, methacrylic acid esters, methacrylic acid amides, methacrylates, methacrylic acid derivatives such as glycidyl methacrylate, etc. Among these, maleic anhydride, fumaric acid, and glycidyl methacrylate are particularly preferred.

[0051] Modification can be performed by known methods, including melt-kneading and reacting at temperatures of 150°C to 350°C using a roll mill, Banbury mixer, extruder, or the like, and heating and reacting in a solvent such as benzene, toluene, or xylene. Furthermore, to facilitate these reactions, it is effective to add a radical generator such as benzoyl peroxide, di-t-butyl peroxide, dicumyl peroxide, t-butyl peroxybenzoate, azobisisobutyronitrile, azobisisovaleronitrile, or 2,3-diphenyl-2,3-dimethylbutane to the reaction system. Of these, 2,3-diphenyl-2,3-dimethylbutane is particularly preferred.

[0052] A preferred modification method is melt-kneading in the presence of a radical generator. During modification, other resins may be added. Specific examples of the compatibilizer include 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 ionomers, 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, modified styrene-based polymers such as maleic anhydride-modified PS, fumaric acid-modified PS, glycidyl methacrylate-modified PS, and amine-modified PS; and modified polyphenylene ether-based polymers such as (styrene-maleic anhydride)-polyphenylene ether graft polymer, maleic anhydride-modified polyphenylene ether, glycidyl methacrylate-modified polyphenylene ether, and amine-modified polyphenylene ether.

[0053] Among these, modified PS and modified polyphenylene ether are particularly preferred. Two or more of the above polymers can also be used in combination. The polar group content in the compatibilizer is preferably 0.01 to 20% by mass, more preferably 0.05 to 10% by mass, based on 100% by mass of the compatibilizer. A content of less than 0.01% by mass requires the addition of a large amount of compatibilizer to exert adhesive properties with the inorganic filler, which is undesirable because it may reduce the mechanical properties, heat resistance, and moldability of the composition. A content of more than 20% by mass is also undesirable because it may reduce compatibility with syndiotactic polystyrene.

[0054] The blending amount of the compatibilizer is 0.1 to 10 parts by mass, preferably 0.5 to 8 parts by mass, and more preferably 1 to 5 parts by mass with respect to 100 parts by mass of the syndiotactic polystyrene resin, the thermoplastic resin and / or the rubber-like elastomer. If it is less than 0.1 part by mass, the adhesion effect with the inorganic filler is small, resulting in insufficient adhesion between the resin and the inorganic filler. Even if it is blended in excess of 10 parts by mass, no improvement in adhesion can be expected and it becomes economically disadvantageous.

[0055] [Inorganic filler] As the inorganic filler, granular or powdery fillers are preferable, and examples thereof include 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 and the like.

[0056] Also, as these fillers, surface-treated ones may be used. The coupling agent used for surface treatment is used to improve the adhesion between the filler and the resin, and any one can be selected from conventionally known ones such as so-called silane-based coupling agents and titanium-based coupling agents and used. Note that only one kind of these inorganic fillers can be used alone or two or more kinds can be used in combination.

[0057] [[Properties of SPS resin film]] The film thickness of each SPS resin film arranged on both sides of the low CTE resin film is not particularly limited and can be appropriately selected according to the purpose, but it is preferably 5 μm to 60 μm, more preferably 10 μm to 60 μm, and even more preferably 20 μm to 55 μm.

[0058] The ratio of the thickness of each SPS resin film (one layer of SPS resin film) arranged on both sides of the low-CTE resin film to the thickness of the low-CTE resin film (SPS resin film:low-CTE resin film) is preferably 1:10 to 10:1, more preferably 1:5 to 5:1, and even more preferably 1:3 to 3:1. If the SPS resin film is too thin, the transmission properties may deteriorate, and if the SPS resin film is too thick, curling may occur or dimensional stability may deteriorate. Furthermore, it is more preferable that the thickness of the SPS resin film is equal to or thinner than that of the low CTE resin film, and therefore, it is particularly preferable that the ratio of the SPS resin film to the low CTE resin film is 1:2 to 1:1.

[0059] The surface roughness (Rz) of the SPS resin film at the interface between the low CTE resin film and the SPS resin film is not particularly limited and can be appropriately selected depending on the purpose, but is preferably, for example, 1 to 10 μm. On the other hand, the surface roughness (Rz) of the SPS resin film at the interface between the SPS resin film and the metal film is not particularly limited and can be appropriately selected depending on the purpose, but is preferably, for example, 1 to 10 μm.

[0060] The melting point of the SPS resin film is preferably 250°C or higher. The SPS resin film preferably has a relative dielectric constant of 2.6 or less, and a dielectric loss tangent of less than 0.0020, more preferably 0.0016 or less, and even more preferably 0.0012 or less. The water absorption rate of the SPS resin film is preferably 0.2% or less, more preferably 0.15% or less, and even more preferably 0.10% or less. Metal-clad laminates (e.g., copper-clad laminates (CCL)) having SPS resin films that satisfy these properties have good electrical properties (dielectric properties) that are compatible with 5G. The lower the relative dielectric constant of the SPS resin film, the more desirable it is, but because the resin must have solder heat resistance, it is preferably 2.0 to 2.6, and more preferably 2.1 to 2.4.The lower the dielectric dissipation factor of the SPS resin film, the more desirable it is, but because the resin must have solder heat resistance, it is preferably 0.0005 to less than 0.0020, more preferably 0.0005 to 0.0016, even more preferably 0.0005 to 0.0012, and particularly preferably 0.0005 to 0.0007.

[0061] Since the dielectric properties of the substrate deteriorate significantly when the substrate absorbs moisture, the water absorption rate of the SPS resin film is, for example, preferably 0 to 0.2%, more preferably 0.01 to 0.15%, and even more preferably 0.03 to 0.06%.

[0062] [Water absorption rate] The water absorption rate can be determined in accordance with JIS K7209A method by measuring the sample by immersing it in water at 23°C for 24 hours. The water absorption rate is calculated from the change in mass before and after immersion in water. Water absorption rate = ((mass after 24-hour moisture test - mass before test) / mass before test) x 100

[0063] Furthermore, the tensile elongation at break in the machine direction (MD) of the SPS resin film is preferably 400% or less.

[0064] The tensile elongation at break in the machine direction (MD) (also referred to as the extrusion direction of the film) of the SPS resin film is 400% or less as described above, but is preferably 2 to 350%. If the elongation is too large, problems such as wrinkles may occur when the film is laminated to a low CTE film or metal film.

[0065] [Elongation at break (%)] The tensile elongation at break of an SPS resin film can be determined in accordance with JIS K7127 by measuring the elongation in the machine direction of the film (i.e., the extrusion direction of the film) at a tensile speed of 50 mm / min and a temperature of 23°C.

[0066] The relative crystallinity of the SPS resin film is preferably 25 to 85%, more preferably 30 to 80%, and even more preferably 35 to 70%. If the relative crystallinity of the SPS resin film is within the above range, it can be expected that the film will have sufficient peel strength and dimensional stability under heat to be usable as a laminate.

[0067] [Relative crystallinity (%)] The crystallinity of an SPS resin film can be expressed as a relative crystallinity. For example, the SPS resin film portion is peeled off from the prepared metal-clad laminate, and the SPS resin film is subjected to thermal analysis using a differential scanning calorimeter at a heating rate of 10°C / min. Based on the results, the relative crystallinity can be calculated using the following formula: Relative crystallinity (%) = {(|ΔHm| - |ΔHc|) / |ΔHm|} × 100 Here, ΔHc represents the calorific value (J / g) of the recrystallization peak, and ΔHm represents the calorific value (J / g) of the melting peak.

[0068] As shown in FIG. 1, SPS resin films are disposed on both sides of low CTE resin film 12, but SPS resin film 13 and SPS resin film 14 may be resin films of the same composition or different compositions as long as they satisfy the above-mentioned requirements.

[0069] For reasons such as improving adhesion, the surface of the SPS resin film is preferably subjected to a surface treatment selected from corona treatment, plasma treatment, and ultraviolet treatment. The surface of the SPS resin film may be subjected to a surface treatment with a coupling agent for the purpose of improving adhesion or the like.

[0070] <Method of manufacturing resin film> The resin film can be obtained, for example, by forming a resin into a film shape by melt extrusion molding. The melt extrusion molding method is a molding method in which a resin material is melt-kneaded using a melt extruder and then continuously extruded from a T-die of the melt extruder. For example, a resin material melted and kneaded in a melt extruder is continuously extruded into a strip-shaped resin film through a T-die at the tip of the melt extruder, and this continuous resin film is placed between rolls arranged next, cooled, and then wound up on a winder, thus producing a resin film. The extruder is not particularly limited, and any extruder such as a single-screw extruder or a twin-screw extruder can be used.

[0071] (Metal-clad laminate) The metal-clad laminate of the present invention is obtained by laminating a metal film on one or both sides of the laminate of the present invention.

[0072] It is made by laminating an SPS resin film, a low CTE resin film, an SPS resin film, and a metal film in this order. The metal-clad laminate of the present invention may have a metal film laminated on both sides of a substrate film, in which case the metal-clad laminate is formed by laminating a metal film, an SPS resin film, a low CTE resin film, an SPS resin film, and a metal film in this order.

[0073] Fig. 2 is a cross-sectional view showing an example of the configuration of the metal-clad laminate of the present invention, in which metal films are laminated on both sides of the laminate. The metal-clad laminate 21 has a metal film 25, an SPS resin film 23, a low CTE resin film 22, an SPS resin film 24, and a metal film 26, which are laminated in this order.

[0074] The metal constituting the metal film is not particularly limited and can be appropriately selected depending on the purpose, but examples thereof include one selected from the group consisting of nickel, copper, silver, tin, gold, palladium, aluminum, chromium, titanium, and zinc, or alloys containing any one or more of these. Among these, copper and alloys containing copper are preferred from the viewpoints of shielding properties and economy. A preferred embodiment of the metal-clad laminate of the present invention is a metal-clad laminate in which a metal foil film is laminated to a laminate. Among them, a copper-clad laminate in which the metal foil is copper foil and a copper foil film (copper foil film) is laminated to a laminate is more preferred.

[0075] <Metal film> A preferred embodiment of the metal film is a metal foil film. The type of metal foil is not particularly limited, and for example, electrolytic metal foil, rolled metal foil, etc. can be used. Among the metal foils, copper foil is more preferable.

[0076] The thickness of the metal foil film is preferably 0.05 μm to 20 μm, more preferably 0.1 to 15 μm, from the viewpoint of ensuring sufficient electrical signal transmission characteristics and enabling a fine pitch of the circuit pattern. The surface roughness (Rz) of the metal foil film at the interface between the metal foil film and the SPS resin film is preferably 0.5 μm or less, more preferably 0.3 μm or less, from the viewpoint of transmission characteristics due to the skin effect.

[0077] <Film thickness of metal-clad laminate> The thickness of the metal-clad laminate is not particularly limited and can be appropriately selected depending on the purpose, but is preferably 10 to 300 μm, for example. If the thickness of the metal-clad laminate is equal to or greater than the lower limit of the above range, it can have excellent handleability and ensure strength. On the other hand, if the thickness is equal to or less than the upper limit of the above range, it can be made lighter, thinner, shorter, and more flexible.

[0078] (Method of manufacturing laminate) The method for producing the laminate includes the steps of arranging an SPS resin film, a low CTE resin film, and an SPS resin film in this order, sandwiching them in a heat press or between heated rolls or a heated belt, and applying heat and pressure to thermocompression bond the resin films together. The thermocompression bonding is preferably carried out at a temperature in the range of -10°C to 30°C, more preferably -10°C to 20°C, relative to the melting point of the SPS resin film. The pressure in thermocompression bonding is preferably 0.2 to 10 MPa, more preferably 1 to 5 MPa, in the case of a heat press or a heating belt, and the thermocompression bonding time is preferably 1 to 30 minutes. In the case of a heating roll, the linear pressure is preferably 4 to 60 kN / m, and the linear speed is preferably 0.5 to 5.0 m / min.

[0079] (Metal-clad laminate manufacturing method) A method for producing a metal-clad laminate includes the steps of arranging a metal film on one or both sides of the laminate, and bonding the laminate and the metal film by thermocompression bonding. The method for producing a metal-clad laminate includes the steps of arranging a metal film, an SPS resin film, a low-CTE resin film, and an SPS resin film in this order, sandwiching them in a heat press or between heated rolls or heated belts, and applying heat and pressure to thermocompression bond the metal film and each resin film together, or arranging a metal film, an SPS resin film, a low-CTE resin film, an SPS resin film, and a metal film in this order, and thermocompression bonding the metal film and each resin film together. The thermocompression bonding is preferably carried out at a temperature in the range of -10°C to 30°C, more preferably -10°C to 20°C, relative to the melting point of the SPS resin film.

[0080] When the metal-clad laminate is a metal-clad laminate having metal films on both sides of a laminate as shown in Figure 2, the metal-clad laminate may be manufactured by laminating a metal film on one side of the laminate using the method described above, and then laminating a metal film on the other side of the laminate using the same method, or the metal films on both sides may be laminated together on the laminate to manufacture a metal-clad laminate having metal films on both sides at the same time.

[0081] Before forming the metal film, the surface of the SPS resin film that will come into contact with the metal film may be surface-treated by corona treatment, plasma treatment, ultraviolet treatment, or the like.

[0082] The laminate of the present invention (particularly, the double-sided metal-clad laminate) has good electrical properties (dielectric properties), excellent adhesion (tightness) between the base film (laminate) and the metal film, and excellent dimensional stability and curl suppression, and therefore can be suitably used in the production of flexible printed circuit boards and rigid printed circuit boards. For example, a printed circuit board can be manufactured by processing the metal substrate of the metal-clad laminate of the present invention into a transmission circuit (conductor circuit) having a predetermined shape by etching or electrolytic plating (semi-additive process (SAP process), modified semi-additive process (MSAP process)). In manufacturing a printed circuit board, after forming a transmission circuit, an interlayer insulating film may be formed on the transmission circuit, and another transmission circuit may be formed on the interlayer insulating film. Also, a solder resist or a coverlay film may be laminated on the transmission circuit. [Example]

[0083] The present invention will be described in further detail below with reference to examples, but the scope of the present invention is not limited to these examples. In the following, parts and percentages are by weight unless otherwise specified.

[0084] (Water absorption rate (%)) The water absorption rate was measured in accordance with JIS K7209A by immersing the sample in water at 23°C for 24 hours. The water absorption rate was calculated from the change in mass before and after immersion in water.

[0085] (Dielectric properties) The dielectric properties (relative permittivity and dielectric loss tangent) were measured at a frequency of around 28 GHz at 23°C and 50% RH using an electronic measuring instrument (product name: Compact USB Vector Network Analyzer MS46122B, manufactured by Anritsu) using the Fabry-Perot method, a type of open-type resonator method. An open-type resonator (product name: Fabry-Perot Resonator Model No. DPS03, manufactured by Keycom) was used.

[0086] (Coefficient of linear thermal expansion (CTE) (ppm / ℃)) The coefficient of linear thermal expansion (CTE) was measured in tension mode using a thermomechanical analyzer (product name: SII / / SS7100, manufactured by Hitachi High-Tech Science Corporation) under conditions of a load of 50 mN and a heating rate of 5°C / min in the range of 10°C to 200°C, and the coefficient of linear thermal expansion (ppm / °C) was calculated from the slope in the range of 20°C to 140°C. Measurements were taken in the transverse direction (TD) of the resin film.

[0087] (Melting point (℃)) The melting point was measured in accordance with JIS K 7121. Specifically, approximately 5 mg of a measurement sample was weighed out from the melt-extruded resin film, and the sample was measured using a differential scanning calorimeter (SII Technologies, Inc.: high-sensitivity differential scanning calorimeter X-DSC 7000) at a heating rate of 10°C / min over a measurement temperature range of 20°C to 380°C.

[0088] The resin films and copper foil films used in the following Examples and Comparative Examples are as follows. The properties of the resin films are shown in Table 1. The SPS resin used in the SPS (2) film and SPS (3) film is the same SPS resin used in molding the SPS (1) film.

[0089] (resin film) SPS film: SPS (1) film manufactured by Shin-Etsu Polymer Co., Ltd. SPS film: SPS (2) film manufactured by Shin-Etsu Polymer Co., Ltd. (SPS resin: synthetic mica = 95:5 mass ratio) SPS film: SPS(3) film manufactured by Shin-Etsu Polymer Co., Ltd. (SPS resin: synthetic mica = 80:20 mass ratio) PI film: PI Kapton (registered trademark) H series manufactured by Toray DuPont PI film: PI Kapton (registered trademark) LK series manufactured by Toray DuPont PI film: Toray DuPont PI Kapton (registered trademark) EN series LCP film: High-melting point LCP (1) film manufactured by Shin-Etsu Polymer Co., Ltd. Stretched PEEK film: Kurabo Stretched PEEK film Unstretched PEEK (polyether ether ketone) film: Unstretched PEEK film manufactured by Shin-Etsu Polymer Co., Ltd. PPS (polyphenylene sulfide) film: PPS film manufactured by Shin-Etsu Polymer Co., Ltd. TPI (thermoplastic polyimide) film: TPI film manufactured by Shin-Etsu Polymer Co., Ltd. LCP film: Low melting point LCP (2) film manufactured by Shin-Etsu Polymer Co., Ltd. (Copper foil film) Copper foil: CF-T9DA-SV-12 manufactured by Fukuda Metal Foil and Powder Industry Co., Ltd. (Rz: 0.21μm, CTE: 18ppm / ℃)

[0090] [Table 1]

[0091] Example 1 A polyimide film (PI) (manufactured by Toray DuPont Co., Ltd., Kapton (registered trademark) LK series film) having a thickness of 50 μm and shown in Table 1 was prepared. The front and back surfaces of the polyimide film were subjected to a corona treatment. On both sides of the polyimide film, a 25 μm-thick SPS film shown in Table 1 (a resin film made of a styrene-based polymer having a syndiotactic structure, manufactured by Shin-Etsu Polymer Co., Ltd.) was placed. Furthermore, a 12 μm thick copper foil film (CF-T9DA manufactured by Fukuda Metal Foil and Powder Co., Ltd.) was placed on both surfaces of the outermost surface, and then the film was sandwiched between 1 mm thick stainless steel plates (SUS plates) using a heat press machine. The surface pressure was set to 3 MPa, the hot plate temperature of the heat press machine was set to 285°C, and the film was heat-pressed for 5 minutes. After the thermocompression bonding, the hot plate of the heat press was cooled to 270°C at a rate of 4°C / min (this cooling method is referred to as Cooling 1), and then the pressure was released, and the obtained copper-clad laminate (CCL) of Example 1 was taken out. The structure of the copper clad laminate of Example 1 thus obtained is shown in Table 2 below. Only the SPS resin film was peeled off from the obtained copper-clad laminate of Example 1, and the relative crystallinity of the SPS resin film was determined according to the following procedure. The values ​​are also shown in Table 2 below.

[0092] (Relative crystallinity) The relative crystallinity of the SPS resin film was determined by peeling only the SPS resin film from the prepared copper-clad laminate, weighing approximately 8 mg of the measurement sample, and measuring it using a differential scanning calorimeter (manufactured by SII Nanotechnologies, Inc. (product name: EXSTAR7000 series X-DSC7000)) at a heating rate of 10°C / min over a temperature range of 20°C to 300°C. The heat values ​​(J / g) of the crystalline melting peak and the recrystallization peak (J / g) obtained during this process were used to calculate the relative crystallinity of the SPS resin film using the following formula: Relative crystallinity (%) = {(|ΔHm| - |ΔHc|) / |ΔHm|} × 100 (Here, ΔHc represents the heat quantity (J / g) of the recrystallization peak, and ΔHm represents the heat quantity (J / g) of the melting peak.)

[0093] The copper-clad laminate of Example 1 was evaluated for curl, dimensions at 250°C, transmission properties, and peel strength by the following evaluation methods. The results are shown in Table 4 below.

[0094] (Curl test) A test specimen measuring 150 x 150 mm was cut out from the obtained copper-clad laminate (CCL), and the copper foil on only one side of the test specimen was removed using an aqueous solution of iron chloride. The test specimen was then placed on a flat glass plate, and the amount of lift at each of the four corners of the test specimen was measured with a ruler, and the average value was calculated.

[0095] [Evaluation criteria for curl test] 〇 The average of the four points is 3cm or less △ The average of the four points is greater than 3cm and less than 5cm × The average of the four points is greater than 5 cm

[0096] (250℃ dimensional test) The 250°C dimensional shrinkage test was performed in accordance with JIS C 6481:1996. First, a copper-clad laminate (CCL) was cut to a size of 300 x 300 mm, and four holes were punched at the edges of this laminate. The distance between the centers of the holes was measured. The laminated copper foil was then removed with an aqueous solution of iron chloride, and the sheet was placed in an oven at 250°C for 30 minutes. After removal, the dimensions were measured. A two-dimensional measuring machine (product name: VMH600, manufactured by Mino Group Co., Ltd.) was used to measure the dimensions.

[0097] [Evaluation criteria for 250℃ dimensional test] Shrinkage rate is 0.2% or less (good shrinkage rate) △ Shrinkage rate is greater than 0.2% and less than 0.4% × Shrinkage rate is greater than 0.4% (poor shrinkage rate)

[0098] (Transmission characteristics test) For the transmission characteristic test, a microstrip line with a length of 10 cm and an impedance of 50 Ω was fabricated by etching the copper foil in a copper-clad laminate (CCL), and the transmission characteristics were measured at 30 GHz under the conditions of a temperature of 25°C and humidity of 50%. The measurement equipment used was a network analyzer E8363B (Keysight Technologies).

[0099] [Evaluation criteria for transmission characteristics test] ◎ Less than 4dB 〇 More than 4dB and less than 5dB △ More than 5dB and less than 10dB × Greater than 10dB

[0100] (peel strength test) For the peel strength test, a copper clad laminate (CCL) was cut into a 25 mm wide test piece, and the copper clad laminate (CCL) was fixed to a support and the copper foil was fixed to a pulling jig at a peel rate of 0.3 mm / min and a peel angle of 180°, in accordance with JIS Z 0237:2009, and the peel strength was measured when the copper foil was pulled from the copper clad laminate (CCL).

[0101] [Evaluation criteria for peel strength test] 〇 7N / cm or more △ 3N / cm or more and less than 7N / cm × 3N / cm or less

[0102] (Examples 2 to 18) Copper-clad laminates of Examples 2 to 18 were produced in the same manner as in Example 1, except that the type of resin film used, the thermocompression bonding temperature, and the cooling method conditions were changed as shown in Table 2. In Table 2 (similar to Table 3 below), cooling method 2 (Cooling 2) and cooling method 3 (Cooling 3) refer to the following methods for cooling the copper-clad laminate after thermocompression bonding and removing it from the hot press. Cooling 2: After thermocompression bonding, the hot plate of the heat press machine is cooled to 230°C at a rate of 4°C / min, and then the pressure is released and the copper-clad laminate is removed. Cooling 3: After thermocompression bonding, the pressure is released without cooling the hot plate of the heat press, and the copper-clad laminate is removed.

[0103] The relative crystallinity of the SPS resin film was determined for the copper-clad laminates produced in Examples 2 to 18 in the same manner as in Example 1. In addition, curl, dimensions at 250°C, transmission properties, and peel strength were evaluated in the same manner as in Example 1. The relative crystallinity of the SPS resin film in the copper-clad laminates of Examples 2 to 18 is shown in Table 2. Table 4 shows the evaluation results of curl, dimensions at 250°C, transmission characteristics, and peel strength for the copper-clad laminates of Examples 2 to 18.

[0104] (Comparative Examples 1 to 5) Copper-clad laminates of Comparative Examples 1 to 5 were produced in the same manner as in Example 1, except that the type of resin film used, the thermocompression bonding temperature, and the cooling method conditions were changed as shown in Table 3.

[0105] The relative crystallinity of the SPS resin film was determined for the copper-clad laminates produced in Comparative Examples 1 to 5 in the same manner as in Example 1. In addition, curl, dimensions at 250°C, transmission properties, and peel strength were evaluated in the same manner as in Example 1. The relative crystallinity of the SPS resin film in the copper-clad laminates of Comparative Examples 1 to 5 is shown in Table 3. Table 4 shows the evaluation results of the curl, dimensions at 250°C, transmission characteristics, and peel strength for the copper-clad laminates of Comparative Examples 1 to 5.

[0106] [Table 2]

[0107] [Table 3]

[0108] [Table 4]

[0109] From the examples, it was confirmed that the metal-clad laminate of the present invention has good electrical properties (dielectric properties), excellent adhesion (tightness) between the base film (laminate) and the metal film, excellent dimensional stability, and suppressed curling. [Industrial Applicability]

[0110] The metal-clad laminate of the present invention can be suitably used in the production of FPC-related products for electronic devices such as smartphones, mobile phones, optical modules, digital cameras, game consoles, notebook computers, and medical instruments. [Explanation of symbols]

[0111] 11 Laminate 12 Low CTE resin film 13 SPS resin film 14 SPS resin film 21 Metal-clad laminate 22 Low CTE resin film 23 SPS resin film 24 SPS resin film 25 Metal Film 26 Metal Film

Claims

1. a low-CTE resin film having a coefficient of linear thermal expansion (CTE) of 50 ppm / °C or less and a melting point of 300°C or less; A laminate obtained by laminating a resin film (SPS resin film) made of a styrene-based polymer (SPS) having a syndiotactic structure on both sides of the low CTE resin film.

2. The laminate according to claim 1, wherein the low CTE resin film is a film made of a resin selected from the group consisting of polyimide (PI), liquid crystal polymer (LCP), and oriented polyether ether ketone (oriented PEEK).

3. The laminate according to claim 1 , wherein the melting point of the SPS resin film is 250° C. or higher.

4. The laminate according to claim 1 , wherein the SPS resin film has a relative dielectric constant of 2.6 or less.

5. 10. The laminate of claim 1, wherein the SPS resin film has a dielectric loss tangent of less than 0.0020.

6. 2. The laminate according to claim 1, wherein the SPS resin film has a water absorption rate of 0.2% or less.

7. The laminate of claim 1 , wherein the low CTE resin film has a water absorption rate of 2.5% or less.

8. 2. The laminate according to claim 1, wherein the ratio of the thickness of the SPS resin film to the thickness of the low CTE resin film (the SPS resin film:the low CTE resin film) is 1:10 to 10:

1.

9. 2. The laminate of claim 1, wherein the SPS resin film has a relative crystallinity of 25% to 85%.

10. 2. The laminate according to claim 1, wherein a surface of the low CTE resin film and / or the SPS resin film has been subjected to a surface treatment selected from the group consisting of a corona treatment, a plasma treatment, and an ultraviolet treatment.

11. The laminate according to claim 1 , wherein the surface of the low CTE resin film and / or the SPS resin film has been subjected to a surface treatment with a coupling agent.

12. A metal-clad laminate obtained by laminating a metal film on one or both sides of the laminate according to any one of claims 1 to 11.

13. 12. A method for producing a laminate according to claim 1, comprising arranging the SPS resin film, the low CTE resin film, and the SPS resin film in this order, and thermocompression bonding the resulting laminate.

14. The method for producing a laminate according to claim 13, wherein the thermocompression bonding is carried out at a temperature in the range of −10° C. to 30° C. relative to the melting point of the SPS resin film.

15. A method for producing a metal-clad laminate, comprising arranging a metal film on one or both sides of the laminate produced by the method of claim 13 and thermocompression bonding the laminate to obtain the metal-clad laminate.

16. a metal film, the SPS resin film, the low CTE resin film, and the SPS resin film are arranged in this order and then thermally compressed; A method for producing a metal clad laminate, comprising arranging a metal film, the SPS resin film, the low CTE resin film, the SPS resin film, and a metal film in this order and thermocompression bonding the metal clad laminate according to claim 12.

17. The method for producing a metal-clad laminate according to claim 16, wherein the thermocompression bonding is performed at a temperature range of -10 ° C to 30 ° C relative to the melting point of the SPS resin film.

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