High frequency multilayer printed circuit board

Abstract

To provide a multilayer printed board for high frequency which is excellent in adhesion with an adhesive layer having low dielectric characteristics, can be laminated with a printed wiring board composed of an insulating layer formed of an epoxy glass cloth laminate, and has low transmission loss by using a printed wiring board in which a resin layer composed of a polyarylene sulfide resin in which a specific thermoplastic resin is dispersed is used as an insulating layer.SOLUTION: The present inventors have found that the above-mentioned problems can be solved by a multilayer printed board for high-frequency use in which a printed wiring board (P1) including an insulating layer formed of an epoxy glass cloth laminate plate is laminated on one surface of a printed wiring board (P2) via an adhesive layer having a low dielectric property, and a resin composition of a polyarylene sulfide resin (A) and a thermoplastic resin (B) other than a polyarylene sulfide-based resin having a glass transition temperature of 140 °C or higher or a melting temperature of 230 °C or higher is used as a low-dielectric material insulating layer.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a high-frequency multilayer printed circuit board in which a printed wiring board (P1) having an insulating layer made of a low-dielectric material is laminated on one or both sides of a printed wiring board (P2) having an insulating layer made of an epoxy glass cloth laminate, via an adhesive layer having low dielectric properties. [Background technology]

[0002] In fields such as high-speed, large-capacity communications (5G) and in-vehicle millimeter-wave radar, there is a demand for high-frequency circuit boards with low transmission loss made from materials with low dielectric constants and low dielectric dissipation factors. However, because low-dielectric materials are expensive, high-frequency multilayer printed circuit boards have been developed that use printed circuit boards made from low-dielectric materials only for high-frequency transmission sections such as antennas, and use printed wiring boards made from epoxy glass cloth laminates, a relatively inexpensive, common material, for low-frequency wiring for control and power supplies. In addition, by forming multiple wiring layers of printed wiring boards that are compatible with high frequencies on the surface layer, high-frequency multilayer printed circuit boards are expected to see an increase in applications requiring higher functionality.

[0003] As a technology related to high-frequency multilayer printed circuit boards, for example, Patent Document 1 discloses an asymmetric multilayer printed wiring board having a printed wiring board with a general-purpose insulating layer and a high-frequency-compatible printed wiring board with an insulating layer made of a low-dielectric material. For example, a method for manufacturing a multilayer printed wiring board with excellent low warpage has been proposed, in which a high-frequency substrate is laminated with an adhesive layer on one side of a printed wiring board having an insulating layer formed of an epoxy glass cloth laminate as a core layer, and a resin layer made of the same adhesive layer is formed separately on the other side. However, while liquid crystal polymers and PTFE have been cited as low-dielectric materials, these materials have poor adhesive properties and therefore cannot achieve sufficient adhesion. Furthermore, the dielectric properties of liquid crystal polymers are highly temperature-dependent, resulting in an increase in dielectric properties in high-temperature environments, while fluorine-based materials such as PTFE are difficult to process. Furthermore, epoxy resin-based prepregs containing reinforcing fibers such as glass cloth in the adhesive layer have been cited, but the prepreg must be thickened to ensure circuit embeddability.

[0004] Known low-dielectric insulating layers include resin layers made from resin compositions such as fluororesins, liquid crystal polymers (LCPs), cyclic olefins (COPs), modified polyimides (MPIs), and polyarylene sulfide resins (PAS resins), such as polyphenylene sulfide resins (PPSs). While fluororesins and LCPs have excellent dielectric properties, they are expensive and suffer from poor adhesion, making lamination and copper wiring difficult. COPs also suffer from poor adhesion and heat resistance, while MPIs are prone to moisture absorption, resulting in poor dielectric properties under high humidity.

[0005] Insulating layers made of polyarylene sulfide resin (PAS) also have low dielectric properties and are excellent in heat resistance, flame retardancy, and low moisture absorption, making them suitable as low-dielectric materials for high-frequency multilayer printed circuit boards. However, they have the problem of insufficient adhesion. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-40797 Summary of the Invention [Problem to be solved by the invention]

[0007] The present invention provides a multilayer printed circuit board for high frequency use with low transmission loss, which has excellent adhesion to an adhesive layer having low dielectric properties and can be laminated with a printed circuit board having an insulating layer formed from an epoxy glass cloth laminate, by using a printed wiring board with an insulating layer made of a resin layer consisting of a polyarylene sulfide resin in which a specific thermoplastic resin is dispersed. [Means for solving the problem]

[0008] As a result of intensive research, the inventors have found that the above-mentioned problems can be solved by a high-frequency multilayer printed circuit board in which a printed wiring board (P1) having an insulating layer made of a low-dielectric material composed of a resin composition of polyarylene sulfide resin (A) and a thermoplastic resin (B) other than polyarylene sulfide resin having a glass transition temperature of 140°C or higher or a melting point of 230°C or higher is laminated on one side of a printed wiring board (P2) having an insulating layer formed of at least an epoxy glass cloth laminate, via an adhesive layer having low dielectric properties, and have thus completed the present invention. That is, the present invention relates to the following [1] to [9].

[0009] [1] A high-frequency multilayer printed circuit board in which a low-dielectric adhesive layer and a printed wiring board (P1) having an insulating layer made of a low-dielectric material are laminated in this order on one side of a printed wiring board (P2) having an insulating layer made of at least an epoxy glass cloth laminate, the low dielectric material is a resin composition containing a polyarylene sulfide resin (A) and a thermoplastic resin (B) other than a polyarylene sulfide resin having a glass transition temperature of 140°C or higher or a melting point of 230°C or higher (hereinafter, may be referred to as "thermoplastic resin (B)"); 1. A multilayer printed circuit board for high frequency use, wherein the low dielectric adhesive layer is a thermosetting resin layer containing a styrene-based elastomer. [2] The high-frequency multilayer printed circuit board according to 1, wherein the thermoplastic resin (B) other than the polyarylene sulfide resin having a glass transition temperature of 140°C or higher or a melting point of 230°C or higher is at least one selected from the group consisting of polycarbonate resin, polyphenylene ether resin, polyethersulfone resin, polyphenylsulfone resin, polyetherimide resin, polysulfone resin, and fluorine-based resin. [3] The high-frequency multilayer printed circuit board according to 1 or 2, wherein the low-dielectric material has a dielectric constant of 3.3 or less. [4] The high frequency multilayer printed circuit board according to any one of 1 to 3, further comprising a modified elastomer (C) in which a reactive group is added to a resin composition of a low dielectric material. [5] The high frequency multilayer printed circuit board according to 4, wherein the modified elastomer (C) is made of an olefin polymer having at least a functional group selected from an epoxy group and an acid anhydride group. [6] The high-frequency multilayer printed circuit board according to 4 or 5, wherein the modified elastomer (C) is contained in an amount of 1 to 15 mass % relative to 100 mass % of the total of the polyarylene sulfide resin (A), the thermoplastic resin (B), and the modified elastomer (C). [7] The high frequency multilayer printed circuit board according to any one of 4 to 6, wherein the α-olefin content of the modified elastomer (C) is 50 to 95 mass % based on the total mass of the modified elastomer. [8] The high frequency multilayer printed circuit board according to any one of 1 to 7, further comprising 0.01 to 5 mass % of a silane coupling agent (D) having at least one functional group selected from an epoxy group, an amino group, and an isocyanate group. [9] A millimeter wave radar and antenna using the high frequency multilayer printed circuit board described in any one of 1 to 8. It is related to. [Effects of the Invention]

[0010] According to the present invention, the adhesiveness of a low-dielectric layer with low transmission loss is improved, making it possible to laminate it with a general-purpose epoxy glass cloth layer, thereby obtaining a high-frequency multilayer printed circuit board suitable for high-frequency applications. [Brief explanation of the drawings]

[0011] [Figure 1] This is a cross-sectional view of a high-frequency multilayer printed circuit board in which a printed wiring board (P1) made from a single-sided copper-clad laminate with a low-dielectric material as an insulating layer is laminated on one side of a printed wiring board (P2) with an insulating layer formed from an epoxy glass cloth laminate, via a low-dielectric adhesive layer. [Figure 2] This is a cross-sectional view of a high-frequency multilayer printed circuit board in which a printed wiring board (P1) made from double-sided copper-clad lamination with a low-dielectric material as an insulating layer is laminated on one side of a printed wiring board (P2) with an insulating layer formed from an epoxy glass cloth laminate, via a low-dielectric adhesive layer. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, embodiments of the present invention will be described in detail.

[0013] [Printed wiring board (P1)] The copper-clad laminate used in the present invention may be manufactured by copper cladding an insulating layer made of a low-dielectric material, or by copper cladding the outermost layer after or simultaneously with attaching an insulating layer made of a low-dielectric material to a printed wiring board (P2). Copper cladding to an insulating layer made of a low-dielectric material may be achieved by thermal lamination, bonding with an adhesive, or forming a metal layer by a plating method such as sputter plating. To reduce transmission loss at high frequencies, it is preferable for the copper foil used to have a smooth surface roughness. For example, an Rz of 2 μm or less is preferred, but copper foil with a surface roughness appropriate for the application can be selected. Plating has the advantage of smoothing the interface between the insulating layer and the metal layer, making it preferable when there is a demand for reduced transmission loss at high frequencies.

[0014] A printed wiring board (P1) with a low-dielectric material as an insulating layer can be obtained by forming a wiring pattern using a known method. The wiring formation method is not particularly limited, and examples include a method of forming wiring by etching a copper-clad laminate, a method of directly forming a metal layer in a required location of a low-dielectric material, and a combination of both methods. Wiring can be formed by a subtractive method, a semi-additive method, a full-additive method, etc.

[0015] [Low dielectric resin composition] The resin composition made of a low-dielectric material used in the printed wiring board (P1) is composed primarily of a polyarylene sulfide resin (A) and a thermoplastic resin (B) other than the polyarylene sulfide resin (A) that has a glass transition temperature of 140°C or higher or a melting point of 230°C or higher. The resin composition has a continuous phase and a dispersed phase, with the continuous phase containing the polyarylene sulfide resin (A) and the dispersed phase containing the thermoplastic resin (B). In this context, the term "main component" refers to a resin composition in which the polyarylene sulfide resin accounts for 51% by mass or more of the total resin composition, assuming the total resin composition to be 100% by mass. By including the thermoplastic resin (B) in the dispersed phase, adhesion to metal layers and low-dielectric adhesive layers can be improved compared to using a PAS resin alone.

[0016] The average dispersed diameter of the dispersed phase is 5 μm or less, preferably 3 μm or less, and more preferably 0.5 to 3 μm. When the average dispersed diameter of the dispersed phase is 5 μm or less, an insulating layer having good mechanical properties and excellent adhesion to the adhesive layer can be obtained.

[0017] [Polyarylene sulfide resin (A)] The polyarylene sulfide resin (A) is the main component of the resin composition, and is a component that has the function of imparting excellent heat resistance, chemical resistance, and dielectric properties to the insulating layer.

[0018] The PAS resin (A) is a polymer containing a structure in which an aromatic ring and a sulfur atom are bonded (specifically, a structure represented by the following formula (1)) as a repeating unit.

[0019] [ka] (In the above formula, R 1 each independently represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, a nitro group, an amino group, a phenyl group, a methoxy group, or an ethoxy group, and each n independently represents an integer of 1 to 4.

[0020] Here, R in the structure represented by formula (1) 1 Preferably, R are all hydrogen atoms. This configuration can further increase the mechanical strength of the PAS resin (A). 1 are hydrogen atoms, the structure represented by the formula (1) includes a structure represented by the following formula (2) (i.e., a structure in which the sulfur atom is bonded to the aromatic ring at the para position) and a structure represented by the following formula (3) (i.e., a structure in which the sulfur atom is bonded to the aromatic ring at the meta position).

[0021] [ka] Among these, the structure represented by formula (1) is preferably a structure represented by formula (2). A PAS resin (A) having a structure represented by formula (2) can further improve heat resistance and crystallinity.

[0022] Furthermore, the PAS resin (A) may contain not only the structure represented by the above formula (1) but also the structures represented by the following formulas (4) to (7) as repeating units.

[0023] [ka]

[0024] The structures represented by formulas (4) to (7) preferably account for 30 mol % or less, and more preferably 10 mol % or less, of all repeating units constituting the PAS resin (A), which can further improve the heat resistance and mechanical strength of the PAS resin (A). The bonding pattern of the structures represented by formulas (4) to (7) may be either random or block.

[0025] The PAS resin (A) may also contain, as a repeating unit, a trifunctional structure represented by the following formula (8), a naphthyl sulfide structure, or the like, in its molecular structure.

[0026] [ka]

[0027] The structure represented by formula (8), naphthyl sulfide structure, etc. are preferably contained in an amount of 1 mol % or less, and more preferably substantially absent, of all repeating units constituting the PAS resin (A). This structure allows the chlorine atom content in the PAS resin (A) to be reduced. The properties of the PAS resin (A) are not particularly limited as long as they do not impair the effects of the present invention. However, the melt viscosity (V6) at 300°C is preferably 100 to 2000 Pa s, and more preferably 120 to 1600 Pa s, as this provides a good balance between fluidity and mechanical strength.

[0028] Furthermore, it is particularly preferred that the PAS resin (A) has a peak in the molecular weight range of 25,000 to 40,000 when measured using gel permeation chromatography (GPC), has a ratio (Mw / Mn) of weight-average molecular weight (Mw) to number-average molecular weight (Mn) of 5 to 10, and has a non-Newtonian index of 0.9 to 1.3. By using such a PAS resin (A), the chlorine atom content in the PAS resin (A) itself can be reduced to the range of 500 to 2,000 ppm without reducing the mechanical strength of the film, facilitating application to halogen-free electronic and electrical parts.

[0029] In this specification, the weight average molecular weight (Mw), number average molecular weight (Mn), and molecular weight distribution (Mw / Mn) are values ​​measured by gel permeation chromatography (GPC) under the following conditions: [Measurement conditions for gel permeation chromatography] Equipment: Ultra-high temperature polymer molecular weight distribution measuring device (SSC-7000 manufactured by Senshu Scientific Co., Ltd.) Column: UT-805L (Showa Denko) Column temperature: 210℃ Solvent: 1-chloronaphthalene Measurement method: UV detector (360 nm) calibrated with six types of monodisperse polystyrene The molecular weight distribution and peak molecular weight are measured using the

[0030] The method for producing the PAS resin (A) is not particularly limited, but examples thereof include: 1) a method in which a dihalogenoaromatic compound, if necessary, a polyhalogenoaromatic compound or other copolymerization component is added in the presence of sulfur and sodium carbonate, and polymerized; 2) a method in which a dihalogenoaromatic compound, if necessary, a polyhalogenoaromatic compound or other copolymerization component is added in a polar solvent, and polymerized in the presence of a sulfidizing agent or the like; and 3) a method in which p-chlorothiophenol, if necessary, and other copolymerization component are added, and self-condensed. Among these methods, method 2) is preferred because it is versatile. During the reaction, an alkali metal salt of carboxylic acid or sulfonic acid or an alkali hydroxide may be added to adjust the degree of polymerization.

[0031] Among the above-mentioned methods 2), the following methods 2-1) and 2-2) are particularly preferred. In method 2-1), a water-containing sulfidizing agent is introduced into a heated mixture containing an organic polar solvent and a dihalogeno aromatic compound at a rate that allows water to be removed from the reaction mixture, and the dihalogeno aromatic compound and the sulfidizing agent, and optionally a polyhalogeno aromatic compound, are added in the organic polar solvent to react. During this reaction, the amount of water in the reaction system is controlled to be within a range of 0.02 to 0.5 moles per mole of the organic polar solvent, thereby producing a PAS resin (A) (see JP-A-07-228699). In the method 2-2), a dihalogenoaromatic compound and, if necessary, a polyhalogenoaromatic compound or other copolymerization component are added in the presence of a solid alkali metal sulfide and an aprotic polar organic solvent, and the resulting mixture is reacted with an alkali metal hydrosulfide and an organic acid alkali metal salt. The amount of the organic acid alkali metal salt is controlled to be within a range of 0.01 to 0.9 mol per mol of the sulfur source, and the amount of water in the reaction system is controlled to be 0.02 mol or less per mol of the aprotic polar organic solvent, thereby producing a PAS resin (A) (see WO2010 / 058713 pamphlet).

[0032] Specific examples of dihalogeno aromatic compounds include p-dihalobenzene, m-dihalobenzene, o-dihalobenzene, 2,5-dihalotoluene, 1,4-dihalonaphthalene, 1-methoxy-2,5-dihalobenzene, 4,4'-dihalobiphenyl, 3,5-dihalobenzoic acid, 2,4-dihalobenzoic acid, 2,5-dihalonitrobenzene, 2,4-dihalonitrobenzene, 2,4-dihaloanisole, p,p'-dihalodiphenyl ether, 4,4'-dihalobenzophenone, 4,4'-dihalodiphenyl sulfone, 4,4'-dihalodiphenyl sulfoxide, 4,4'-dihalodiphenyl sulfide, and compounds of the above compounds having an alkyl group having 1 to 18 carbon atoms on the aromatic ring. Examples of the polyhalogeno aromatic compounds include 1,2,3-trihalobenzene, 1,2,4-trihalobenzene, 1,3,5-trihalobenzene, 1,2,3,5-tetrahalobenzene, 1,2,4,5-tetrahalobenzene, and 1,4,6-trihalonaphthalene. The halogen atoms contained in the above compounds are preferably chlorine atoms or bromine atoms.

[0033] The reaction mixture containing the PAS resin (A) obtained by the polymerization step can be post-treated by a known, commonly used method, which is not particularly limited, but includes, for example, the following methods (1) to (5):

[0034] In method (1), after the polymerization reaction is completed, the solvent is first distilled off under reduced pressure or normal pressure, either directly from the reaction mixture or after adding an acid or a base, and then the solid obtained after solvent distillation is washed once or twice or more times with a solvent such as water, the reaction solvent (or an organic solvent having a similar solubility to the low-molecular-weight polymer), acetone, methyl ethyl ketone, or an alcohol, and then neutralized, washed with water, filtered, and dried. In the method (2), after the polymerization reaction is completed, a solvent such as water, acetone, methyl ethyl ketone, alcohols, ethers, halogenated hydrocarbons, aromatic hydrocarbons, or aliphatic hydrocarbons (a solvent that is soluble in the polymerization solvent used and is a poor solvent for at least the PAS resin (A)) is added to the reaction mixture as a precipitant to precipitate the solid products such as the PAS resin (A) and inorganic salts, which are then filtered, washed, and dried. In the method (3), after the polymerization reaction is completed, the reaction mixture is added with a reaction solvent (or an organic solvent having a solubility equivalent to that of the low-molecular-weight polymer) and stirred, and then filtered to remove the low-molecular-weight polymer. The mixture is then washed once or twice or more times with a solvent such as water, acetone, methyl ethyl ketone, or an alcohol, and then neutralized, washed with water, filtered, and dried. In the method (4), after the polymerization reaction is completed, water is added to the reaction mixture, followed by washing with water, filtration, and if necessary, acid is added during the water washing for acid treatment, and then drying. In the method (5), after the polymerization reaction is completed, the reaction mixture is filtered, washed once or twice or more times with the reaction solvent as required, further washed with water, filtered and dried.

[0035] Examples of acids that can be used in the above method (4) include organic acids such as saturated fatty acids such as formic acid, acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, and monochloroacetic acid; unsaturated fatty acids such as acrylic acid, crotonic acid, and oleic acid; aromatic carboxylic acids such as benzoic acid, phthalic acid, and salicylic acid; dicarboxylic acids such as maleic acid and fumaric acid; and sulfonic acids such as methanesulfonic acid and paratoluenesulfonic acid; and inorganic acids such as hydrochloric acid, sulfuric acid, sulfurous acid, nitric acid, nitrous acid, and phosphoric acid. Examples of hydrogen salts include sodium hydrogen sulfide, disodium hydrogen phosphate, sodium hydrogen carbonate, etc. However, when used in actual equipment, organic acids are preferred because they are less corrosive to metal members. In the above methods (1) to (5), the PAS resin (A) may be dried in a vacuum, in air, or in an inert gas atmosphere such as nitrogen.

[0036] In particular, the PAS resin (A) post-treated by the method (4) above has an increased amount of acid groups bonded to its molecular terminals, which enhances the dispersibility of the thermoplastic resin (B) and modified elastomer (C) when mixed with them. Carboxyl groups are particularly preferred as the acid groups. When the content of PAS resin (A) is 50% by mass or more based on the total mass of the resin components, the inherent heat resistance and chemical resistance of the PAS resin can be imparted to the film, while maintaining its stretchability.

[0037] [Thermoplastic resin other than polyarylene sulfide resin (B)] The thermoplastic resin (B) other than the polyarylene sulfide resin of the present invention may be any thermoplastic resin other than a PAS resin having a glass transition temperature of 140°C or higher or a melting point of 230°C or higher. A thermoplastic resin (B) having a glass transition temperature of 140°C or higher or a melting point of 230°C or higher can suppress significant deformation and shrinkage of the insulating layer even at temperatures (120°C to 200°C) during lamination of a printed circuit board, enhance the surface modification effect of corona treatment or plasma treatment, and improve adhesion. Furthermore, affinity with the styrene elastomer contained in the adhesive layer can be improved, and a laminate consisting of a printed wiring board (P1) made of the resin composition of the present invention and an adhesive layer having low dielectric properties can become a substrate with high adhesive strength.

[0038] The thermoplastic resin (B) may be any thermoplastic resin having a glass transition temperature of 140°C or higher or a melting point of 230°C or higher, and examples thereof include various polymers such as polycarbonate resin, polyphenylene ether resin, polyethersulfone resin, polyphenylsulfone resin, polyetherimide resin, polysulfone resin, and fluorine-based resin, as well as blends containing two or more of these polymers or blends containing at least one of these polymers. Among these, polyphenylene ether resin or fluorine-based resin is preferred from the viewpoints of low dielectric properties, miscibility with PAS-based resin, adhesion to the adhesive layer, and low moisture absorption.

[0039] The content of the thermoplastic resin (B) in the resin composition constituting the insulating layer may be 1 to 49% by mass, but is preferably 3 to 40% by mass. If the content of the thermoplastic resin (B) is within the above range, the physical properties of the insulating substrate are maintained and the adhesiveness with the adhesive layer is effective.

[0040] [Polyphenylene ether resin] Polyphenylene ether resins (hereinafter sometimes referred to as "PPE resins") are components that have the function of lowering the dielectric constant and dielectric loss tangent of resin compositions of low-dielectric materials, and are preferred because they can improve adhesion due to their high compatibility with the styrene portion of the styrene elastomer contained in the adhesive layer.

[0041] The PPE resin is a homopolymer and / or copolymer having a structural moiety represented by the following structural formula (9).

[0042] [ka]

[0043] In the above formula, each R2 is independently a hydrogen atom, a halogen atom, a primary alkyl group having 1 to 7 carbon atoms, a secondary alkyl group having 1 to 7 carbon atoms, a phenyl group, a haloalkyl group, an aminoalkyl group, a hydrocarbonoxy group, or a halohydrocarbonoxy group in which at least two carbon atoms separate the halogen atom from the oxygen atom, and each m is independently an integer of 1 to 4.

[0044] Specific examples of PPE resins include poly(2,6-dimethyl-1,4-phenylene ether), poly(2-methyl-6-ethyl-1,4-phenylene ether), poly(2-methyl-6-phenyl-1,4-phenylene ether), and poly(2,6-dichloro-1,4-phenylene ether), as well as polyphenylene ether copolymers such as copolymers of 2,6-dimethylphenol with other phenols (e.g., 2,3,6-trimethylphenol or 2-methyl-6-butylphenol). Of these, poly(2,6-dimethyl-1,4-phenylene ether) and copolymers of 2,6-dimethylphenol and 2,3,6-trimethylphenol are preferred, with poly(2,6-dimethyl-1,4-phenylene ether) being even more preferred.

[0045] The number average molecular weight of the PPE resin is preferably 1,000 or more, more preferably 1,500 to 50,000, and even more preferably 1,500 to 30,000.

[0046] [Fluorine-based resin] Fluorine-based resins are most preferred as the thermoplastic resin (B) due to their low dielectric properties, and those having at least one reactive functional group selected from the group consisting of a carbonyl group-containing group, a hydroxy group, an epoxy group, and an isocyanate group are preferred. Two or more of these reactive functional groups may be included. Of these, carbonyl group-containing groups are preferred because of their excellent reactivity with the PAS resin (A). Examples of carbonyl group-containing groups include groups having a carbonyl group between carbon atoms of a hydrocarbon group, carbonate groups, carboxy groups, haloformyl groups, alkoxycarbonyl groups, acid anhydride groups, and polyfluoroalkoxycarbonyl groups.

[0047] Methods for introducing reactive functional groups into fluororesin include: (1) using a monomer having a reactive functional group when producing the main chain of a fluororesin having a reactive functional group through a polymerization reaction; (2) using a chain transfer agent that generates a radical having a reactive functional group to produce a fluororesin having a functional group through a polymerization reaction; (3) using a polymerization initiator that generates a radical having a reactive functional group to produce a fluororesin having a functional group through a polymerization reaction; (4) modifying the fluororesin by a technique such as oxidation or thermal decomposition; and (5) blending a compound or resin that is compatible with the fluororesin and contains the functional group.

[0048] Examples of the reactive functional group-containing monomer include a monomer having a carbonyl group-containing group, an epoxy group-containing monomer, a hydroxy group-containing monomer, and an isocyanate group-containing monomer.

[0049] Examples of the monomer having a carboxyl group-containing group include unsaturated dicarboxylic acids (maleic acid, itaconic acid, citraconic acid, crotonic acid, himic acid, 5-norbornene-2,3-dicarboxylic acid, maleic acid), their unsaturated dicarboxylic acid anhydrides, unsaturated monocarboxylic acids (acrylic acid, methacrylic acid), and vinyl esters (vinyl acetate, vinyl chloroacetate, vinyl butanoate, vinyl pivalate, vinyl benzoate, vinyl crotonate).

[0050] Examples of the hydroxy group-containing monomer include hydroxy group-containing vinyl ester, hydroxy group-containing vinyl ether, hydroxy group-containing allyl ether, hydroxy group-containing (meth)acrylate, hydroxyethyl crotonate, and allyl alcohol.

[0051] Examples of epoxy group-containing monomers include unsaturated glycidyl ethers (allyl glycidyl ether, 2-methylallyl glycidyl ether, vinyl glycidyl ether, etc.) and unsaturated glycidyl esters (glycidyl acrylate, glycidyl methacrylate, etc.).

[0052] Examples of the isocyanate group-containing monomer include 2-(meth)acryloyloxyethyl isocyanate, 2-(2-(meth)acryloyloxyethoxy)ethyl isocyanate, and 1,1-bis((meth)acryloyloxymethyl)ethyl isocyanate.

[0053] The amount of reactive functional groups contained in the fluororesin is preferably 0.01 to 3 mol %, more preferably 0.03 to 2 mol %, and even more preferably 0.05 to 1 mol %, based on the total units constituting the fluororesin. When the amount of reactive functional groups is within the above range, the reactivity with the PAS resin is excellent and deterioration of fluidity can be suppressed.

[0054] The structure of the fluororesin is not particularly limited, but is composed of at least one type of fluoroolefin unit. Examples include tetrafluoroethylene polymers, copolymers with perfluoro(alkyl vinyl ether), hexafluoropropylene, vinylidene fluoride, vinyl fluoride, trifluoroethylene, and chlorotrifluoroethylene, as well as copolymers with fluorine-free ethylene monomers such as ethylene, propylene, butene, and alkyl vinyl ethers. Specific examples include polytetrafluoroethylene, ethylene-tetrafluoroethylene copolymers, tetrafluoroethylene-perfluoro(alkyl vinyl ether) copolymers, tetrafluoroethylene-hexafluoropropylene copolymers, ethylene-tetrafluoroethylene-hexafluoropropylene copolymers, polyvinylidene fluoride, and polychlorotrifluoroethylene. Among these, ethylene-tetrafluoroethylene copolymers, tetrafluoroethylene-perfluoro(alkyl vinyl ether) copolymers, and tetrafluoroethylene-hexafluoropropylene copolymers are preferred because of their ease of melt extrusion.

[0055] The melting point of the fluororesin used in the present invention is not particularly limited, but is preferably 230° C. or higher, more preferably 270° C. or higher. When the melting point of the fluororesin is within the above range, heat resistance can be maintained and good melt extrusion stability can be obtained.

[0056] The glass transition temperature of the fluororesin used in the present invention is not particularly limited, but is preferably 130°C or lower, more preferably 120°C or lower, and even more preferably 110°C or lower. When a fluororesin having such a glass transition temperature is used to produce a stretched film (one form of insulating substrate) using a mixture of the fluororesin and the PAS resin (A), the dispersed phase of the fluororesin is also stretched at the stretching temperature of the continuous phase PAS resin (A), thereby preventing delamination at the interface between the continuous phase PAS resin (A) and the dispersed phase fluororesin. This prevents breakage during stretching, and also allows the production of a film with excellent mechanical properties.

[0057] [Modified elastomer (C)] The modified elastomer (C) has a reactive group capable of reacting with at least one of the PAS resin (A) and the thermoplastic resin (B), thereby improving the mechanical strength (tensile properties, folding strength, etc.) of the insulating layer. In addition, it has excellent affinity with the styrene elastomer contained in the adhesive layer, thereby improving adhesion. The reactive group of the modified elastomer (C) is preferably at least one selected from the group consisting of an epoxy group and an acid anhydride group, and more preferably an epoxy group, which can react rapidly with the functional groups of the PAS resin (A) and the thermoplastic resin (B).

[0058] Examples of such modified elastomer (C) include a copolymer containing a repeating unit based on an α-olefin and a repeating unit based on a vinyl polymerizable compound having the above-mentioned functional group, and a copolymer containing a repeating unit based on an α-olefin, a repeating unit based on a vinyl polymerizable compound having the above-mentioned functional group, and a repeating unit based on an acrylic acid ester.

[0059] Examples of the α-olefin include α-olefins having 2 to 8 carbon atoms, such as ethylene, propylene, and butene-1. Examples of the vinyl polymerizable compound having a functional group include α,β-unsaturated carboxylic acids and esters thereof, such as acrylic acid, methacrylic acid, acrylic acid esters, and methacrylic acid esters; α,β-unsaturated dicarboxylic acids such as maleic acid, fumaric acid, itaconic acid, and other unsaturated dicarboxylic acids having 4 to 10 carbon atoms; mono- or diesters thereof; and acid anhydrides thereof, such as α,β-unsaturated dicarboxylic acids; esters thereof; and acid anhydrides thereof; and α,β-unsaturated glycidyl esters.

[0060] The α,β-unsaturated glycidyl ester is not particularly limited, but examples thereof include compounds represented by the following formula (10).

[0061] [ka]

[0062] In the above formula, R 3 is an alkenyl group having 1 to 6 carbon atoms. Examples of the alkenyl group having 1 to 6 carbon atoms include a vinyl group, a 1-propenyl group, a 2-propenyl group, a 1-methylethenyl group, a 1-butenyl group, a 2-butenyl group, a 1-methyl-1-propenyl group, a 1-methyl-2-propenyl group, a 2-methyl-1-propenyl group, a 2-methyl-2-propenyl group, a 1-pentenyl group, a 2-pentenyl group, a 3-pentenyl group, a 4-pentenyl group, a 1-methyl-1-pentenyl group, a 1-methyl-3-pentenyl group, a 1,1-dimethyl-1-butenyl group, a 1-hexenyl group, and a 3-hexenyl group.

[0063] R 4 are each independently a hydrogen atom, a halogen atom, or an alkyl group having 1 to 6 carbon atoms. Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom. Examples of the alkyl group having 1 to 6 carbon atoms 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, a 2-methylbutyl group, a 3-methylbutyl group, a 2,2-dimethylpropyl group, a hexyl group, a 1-methylpentyl group, a 2-methylpentyl group, a 3-methylpentyl group, a 4-methylpentyl group, a 2,2-dimethylbutyl group, a 2,3-dimethylbutyl group, a 2,4-dimethylbutyl group, a 3,3-dimethylbutyl group, and a 2-ethylbutyl group.

[0064] Specific examples of the α,β-unsaturated glycidyl ester include glycidyl acrylate and glycidyl methacrylate, with glycidyl methacrylate being preferred. The proportion of repeating units based on α-olefin in the modified elastomer (C) is preferably 50 to 95 mass%, more preferably 50 to 80 mass%. When the proportion of repeating units based on α-olefin is within the above range, the stretching uniformity of the film, folding endurance, and adhesive strength with the adhesive layer can be improved. The proportion of repeating units based on a vinyl polymerizable compound having a functional group in the modified elastomer (C) is preferably 1 to 30 mass %, more preferably 2 to 20 mass %. When the proportion of repeating units based on a vinyl polymerizable compound having a functional group is within the above range, not only the desired improvement effect but also good extrusion stability can be obtained.

[0065] The content of the modified elastomer (C) in the resin composition is preferably 1 to 15 mass %, more preferably 2 to 10 mass %. When the content of the modified elastomer (C) is within the above range, the effects of improving the folding endurance, adhesive strength, etc. are significantly exhibited.

[0066] [Silane coupling agent (D)] In the present invention, it is preferable to use a silane coupling agent as a component that has the function of increasing the affinity (interaction) between the PAS resin (A) and other components (thermoplastic resin (B) other than the PAS resin, modified elastomer (C)), which dramatically improves the dispersibility of the other components in the PAS resin (A) and enables the formation of a good morphology.

[0067] The silane coupling agent (D) is preferably a compound having a functional group capable of reacting with a carboxyl group. The silane coupling agent (D) reacts with the PAS resin (A), the thermoplastic resin (B), and the modified elastomer (C) to form a strong bond therewith. As a result, the effects of the silane coupling agent are more pronounced, and the dispersibility of the thermoplastic resin (B) and the modified elastomer (C) in the PAS resin (A) can be particularly improved.

[0068] Examples of such silane coupling agents include compounds having an epoxy group, an isocyanate group, or an amino group. Specific examples of the silane coupling agent include epoxy group-containing alkoxysilane compounds such as γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, and β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane; isocyanato group-containing alkoxysilane compounds such as γ-isocyanatopropyltrimethoxysilane, γ-isocyanatopropyltriethoxysilane, γ-isocyanatopropylmethyldimethoxysilane, γ-isocyanatopropylmethyldiethoxysilane, γ-isocyanatopropylethyldimethoxysilane, γ-isocyanatopropylethyldiethoxysilane, and γ-isocyanatopropyltrichlorosilane; amino group-containing alkoxysilane compounds such as γ-(2-aminoethyl)aminopropylmethyldimethoxysilane, γ-(2-aminoethyl)aminopropyltrimethoxysilane, and γ-aminopropyltrimethoxysilane; and hydroxyl group-containing alkoxysilane compounds such as γ-hydroxypropyltrimethoxysilane and γ-hydroxypropyltriethoxysilane.

[0069] The content of the silane coupling agent in the resin composition is preferably 0.01 to 5 mass %, more preferably 0.05 to 2.5 mass %. When the content of the silane coupling agent is within the above range, the effect of improving the dispersibility of other components in the PAS resin (A) is significantly exhibited.

[0070] [Additives] The resin composition made of a low dielectric material may contain a plasticizer, a weathering agent, an antioxidant, a heat stabilizer, an ultraviolet stabilizer, a lubricant, an antistatic agent, and a colorant, as long as the effects of the present invention are not impaired.

[0071] [Insulating layer made of low-dielectric material (resin composition and film)] <Method of manufacturing resin composition> The resin composition can be produced by any method, including, but not limited to, homogeneous mixing of the PAS resin (A), the thermoplastic resin (B), and, if necessary, other components (such as the modified elastomer (C) and silane coupling agent) in a tumbler mixer or Henschel mixer, followed by melt-kneading in a twin-screw extruder. This melt-kneading may be performed in a shear flow field, an extensional flow field, or both. The melt-kneading is preferably performed under conditions where the ratio of the throughput (kg / hr) of the kneaded mixture to the screw rotation speed (rpm) (output rate / screw rotation speed) is 0.02 to 0.2 (kg / hr rpm).

[0072] The set temperature during mixing is selected within a range of +5 to +70°C above the melting point of the PAS resin (A) or the thermoplastic resin (B), whichever has the higher melting point, and more preferably within a range of +10 to +50°C. If the set temperature is lower than the melting points of the PAS resin (A) and the thermoplastic resin (B), the presence of partially unmelted PAS resin (A) or thermoplastic resin (B) will cause a significant increase in the viscosity of the composition, placing a heavy load on the twin-screw extruder, which is undesirable from the standpoint of productivity. More specifically, a preferred method involves feeding each component into a twin-screw extruder and melt-kneading them at the aforementioned set temperature, with a resin temperature in the strand die of approximately 330°C. In this case, the output rate of the kneaded product is in the range of 5 to 50 kg / hr at a rotation speed of 250 rpm. From the perspective of particularly enhancing the dispersibility of each component, the output rate of the kneaded product is preferably 20 to 35 kg / hr at a rotation speed of 250 rpm. Therefore, the ratio of the output rate (kg / hr) of the kneaded product to the screw rotation speed (rpm) (output rate / screw rotation speed) is more preferably 0.08 to 0.14 (kg / hr·rpm).

[0073] <Film manufacturing method> One form of the insulating layer made of the low dielectric material of the present invention is a film made of a resin composition mainly composed of a PAS resin (A), and among these, a biaxially stretched film is preferred. The use of a biaxially stretched film can improve the heat resistance of the printed wiring board (P1). In one embodiment of such a film, the PAS resin (A) serves as a matrix (continuous phase), and particles (dispersed phase) containing the thermoplastic resin (B) are dispersed in this matrix. The modified elastomer (C) is present on the surface of the particles of the thermoplastic resin (B) (i.e., the interface between the matrix and the particles), inside the particles of the thermoplastic resin (B), or as particles (dispersed phase) separate from the particles of the thermoplastic resin (B).

[0074] The present inventors also believe that the modified elastomer (C) also functions as a compatibilizer between the PAS resin (A) and the thermoplastic resin (B), thereby finely dispersing the particles in the matrix, thereby preventing film tearing during stretching, improving the mechanical strength (such as folding endurance) of the biaxially stretched film and the mechanical strength of the laminate. Furthermore, the present inventors believe that the combined use of the modified elastomer (C) with a silane coupling agent further improves the adhesiveness at the interface between the matrix and the particles via the modified elastomer (C), further improving the mechanical strength (such as folding endurance) of the biaxially stretched film and the laminate.

[0075] The average particle size (average dispersed diameter) of the particles (dispersed phase) dispersed in the matrix in the film state is preferably 5 μm or less, more preferably 0.5 μm to 5 μm, and even more preferably 0.5 μm to 3 μm. If the average particle size of the particles is within the above range, the performance as a biaxially stretched film and substrate is maintained, and the adhesion to the metal layer and adhesive layer is good.

[0076] The film is preferably a biaxially stretched film obtained by biaxially stretching a sheet obtained from the resin composition. When a biaxially stretched film is used, the PAS resin (A) constituting the matrix crystallizes with its molecular chains oriented, allowing for a film with high dimensional accuracy to be obtained. However, if cost reduction is required, a non-stretched film, which requires fewer processes, can also be selected.

[0077] The film may have at least one insulating layer of a resin composition comprising the low dielectric material of the present invention as the outermost layer, and may be a multilayer film in which layers comprising other resin compositions are laminated directly or via an adhesive layer or the like.

[0078] The method for producing the multilayer film used in the present invention is not particularly limited, but examples thereof include a coextrusion method in which, in the case of a multilayer structure, the resins or resin mixtures used for each resin layer are heated and melted in separate extruders, laminated in the molten state in the desired laminate structure by a coextrusion lamination die method, a feed block method, or the like, and then formed into a sheet by an inflation method, a T-die chill roll method, or the like. This coextrusion method is preferred because it allows for relatively free adjustment of the thickness ratio of each layer and produces an unstretched laminate sheet with excellent cost performance.

[0079] In the method for producing the unstretched sheet, first, the resin composition is dried at 140°C for 3 hours or more, and then fed into an extruder heated to 280 to 320°C. The molten material is then extruded into a sheet from a T-die after passing through an extruder. Next, the sheet-like kneaded product is cooled and solidified by being brought into close contact with a cooling roll having a surface temperature of 20 to 50° C. This results in an unoriented, unstretched sheet.

[0080] Next, in the case of biaxial stretching, the unstretched sheet and unstretched laminate sheet obtained above are biaxially stretched. As the stretching method, a sequential biaxial stretching method, a simultaneous biaxial stretching method, or a combination of these methods can be used. When biaxially stretching is performed by the sequential biaxial stretching method, for example, the obtained unstretched sheet is heated with a group of heating rolls and stretched in the longitudinal direction (MD direction) by 1.5 to 4 times (preferably 2 to 3.8 times) in one stage or in two or more stages, and then cooled with a group of cooling rolls at 30 to 60°C. The stretching temperature is preferably from the glass transition temperature (Tg) of the PAS resin (A) to Tg+40°C, more preferably from Tg+5°C to Tg+30°C, and even more preferably from Tg+5°C to Tg+20°C.

[0081] Next, the film is stretched in the transverse direction (TD) using a tenter. Both ends of the film stretched in the MD are held with clips and introduced into the tenter, where it is stretched in the TD. The stretching ratio is preferably 1.5 to 4 times, and more preferably 2.0 to 3.8 times. The stretching temperature is preferably from the glass transition temperature (Tg) of the PAS resin (A) to Tg+40°C, more preferably from Tg+5°C to Tg+30°C, and even more preferably from Tg+5°C to Tg+20°C.

[0082] The ratio of the stretching ratio in the width direction (TD direction) of the biaxially stretched film to the stretching ratio in the longitudinal direction (MD direction) of the biaxially stretched film (width direction (TD direction)) / (longitudinal direction (MD direction)) is preferably 0.7 to 1.5, more preferably 0.9 to 1.3.

[0083] Next, the stretched film is heat-set under tension or while relaxed in the width direction. The heat setting temperature is not particularly limited, but is preferably 200 to 280°C, more preferably 220 to 280°C, and even more preferably 240 to 275°C. The heat setting may be carried out in two stages with different heat setting temperatures. In this case, the heat setting temperature in the second stage is preferably 10 to 40°C higher than the heat setting temperature in the first stage. A stretched film heat set at a heat setting temperature within this range has improved heat resistance and mechanical strength. The heat setting time is preferably 1 to 60 seconds.

[0084] Furthermore, this film is cooled while being relaxed in the width direction in a temperature zone of 50 to 280° C. The relaxation rate is preferably 0.5 to 13%, more preferably 2 to 11%, and even more preferably 3 to 10%.

[0085] To further enhance the dimensional stability of this film, a heat treatment (annealing treatment) may be performed. Examples of heat treatment methods after stretching include known methods such as hot air blowing, infrared radiation, and microwave radiation. Among these, infrared radiation is preferred because it allows for uniform and precise heating. The heat treatment temperature is preferably 150 to 260°C, more preferably 160 to 240°C. Heat treatment at a temperature below 150°C does not provide sufficient stress relaxation, making it impossible to suppress the thermal shrinkage rate of the film after production. Furthermore, heat treatment temperatures above 260°C cause partial melting of the crystalline phase of polyphenylene sulfide, resulting in loss of orientation, thereby eliminating the dimensional stability effect of molecular orientation. The heat treatment time is preferably 3 to 300 seconds, more preferably 5 to 100 seconds.

[0086] The thickness of the film is not particularly limited, but is preferably 10 to 300 μm, more preferably 10 to 200 μm, and even more preferably 10 to 150 μm. A film of such a thickness can provide a substrate with sufficient mechanical strength and insulating properties.

[0087] To enhance the adhesiveness of the film of the present invention, the film may be subjected to a surface treatment such as corona discharge treatment (including corona treatment under various gas atmospheres), plasma treatment (including plasma treatment under various gas atmospheres), or oxidation treatment using chemicals, ultraviolet light, electron beams, or the like.

[0088] [Low dielectric adhesive layer (bonding sheet) (hereinafter sometimes referred to as "BS")] The adhesive layer is used for interlayer bonding of multilayer flexible wiring boards or for bonding reinforcing plates of flexible wiring boards, and is called a bonding sheet. It is not particularly limited, but from the viewpoints of good adhesion to a circuit formation layer formed from a metal layer, an insulating layer made of a resin composition mainly composed of a polyarylene sulfide resin, and an epoxy glass cloth laminate, excellent conformability for embedding circuit patterns, and low dielectric properties, it is preferable to use an adhesive layer containing a thermosetting resin containing a styrene-based elastomer as its main component. In addition to the thermosetting resin, additives such as a curing agent, a curing accelerator, a flexible component, an inorganic filler, and a flame retardant may be included as necessary.

[0089] Styrenic elastomers are copolymers of styrene and olefins (e.g., conjugated dienes such as butadiene and isoprene) and / or their hydrogenated products. Styrenic elastomers are block copolymers with styrene as the hard segment and conjugated dienes as the soft segment. Examples of styrene elastomers include styrene / butadiene / styrene block copolymers, styrene / isoprene / styrene block copolymers, styrene / ethylene / butylene / styrene block copolymers, styrene / ethylene / propylene / styrene block copolymers, and styrene / butadiene block copolymers. Furthermore, styrene / ethylene / butylene / styrene block copolymers, styrene / ethylene / propylene / styrene block copolymers, and styrene / butadiene block copolymers (also called hydrogenated styrene elastomers) in which the double bonds of the conjugated diene component have been eliminated by hydrogenation may also be used. One or more types of styrene elastomers may be used in combination.

[0090] The styrene elastomer may have a functional group such as a carboxyl group or a glycidyl group. Modification of a styrene elastomer containing a functional group can be achieved, for example, by copolymerizing an unsaturated carboxylic acid during polymerization of the styrene elastomer. Alternatively, the modification can be achieved by heating and kneading the styrene elastomer and the unsaturated carboxylic acid in the presence of an organic peroxide. Examples of unsaturated carboxylic acids include acrylic acid, methacrylic acid, maleic acid, itaconic acid, fumaric acid, maleic anhydride, itaconic anhydride, and fumaric anhydride. The amount of modification with the unsaturated carboxylic acid is preferably 0.1 to 10% by mass.

[0091] The weight average molecular weight of the styrene elastomer is preferably 10,000 or more, more preferably 10,000 to 300,000, and even more preferably 50,000 to 250,000. Within this range, the adhesive strength (connection reliability), flexibility, and conformability can be improved.

[0092] The styrene ratio in the styrene-based elastomer is preferably less than 50%, more preferably 5 to 45%, and even more preferably 10 to 40%. By setting the ratio in this range, it is possible to improve the flex resistance, adhesive strength (connection reliability), flexibility, and conformability.

[0093] The content of the styrene elastomer in the adhesive layer is preferably 50% by mass or more relative to 100% by mass of the solid content of the adhesive layer, and if it is less than 50% by mass, the adhesive strength, flex resistance, and conformability will be poor.

[0094] As the thermosetting resin containing a styrene-based elastomer, one or more known thermosetting resins can be used in combination. In particular, epoxy-based compounds are preferably used from the viewpoint of heat resistance. The epoxy-based compound may contain at least two epoxy groups in the molecule, and examples thereof include bisphenol A-type epoxy resins, bisphenol F-type epoxy resins, bisphenol S-type epoxy resins, bisphenol AD-type epoxy resins, resorcinol-type epoxy resins, hydroquinone-type epoxy resins, catechol-type epoxy resins, hydroxynaphthalene-type epoxy resins, biphenyl-type epoxy resins, tetramethylbiphenyl-type epoxy resins, phenol novolac-type epoxy resins, and cresol novolac-type epoxy resins. The epoxy resins may be used alone or in combination of two or more.

[0095] Examples of the curing agent include amine compounds such as dicyandiamide, diaminodiphenylmethane, diaminodiphenyl sulfide, diaminobenzophenone, diaminodiphenyl sulfone, and diethyltriamine; imidazole derivatives such as 2-alkyl-4-methylimidazole, 2-phenyl-4-alkylimidazole, 2-phenyl-4-alkylimidazole, and 1-cyanoethyl-2-methylimidazole; DBU compounds such as 1,8-diazabicyclo[5,4,0]undecene and 7,1,4-diazabicyclo[2,2,2]octane; phosphorus compounds such as triphenylphosphine and triethylphosphine; benzyldimethylamine, 2-(dimethylamino)phenol, and 2, Examples of the fluorinated organic compounds include aromatic tertiary amines such as 4,6-tris(diaminomethyl)phenol, alicyclic tertiary amines such as dimethylcyclohexylamine, organic acids such as phthalic anhydride, trimellitic anhydride, and pyromellitic acid, amine complexes of boron trifluoride such as boron triethylamine complex and boron trifluoride piperazine complex, amine complexes of boron trichloride, phosphorus pentafluoride, arsenic pentafluoride, antimony pentafluoride, boron tetrafluoride amine complex and boron trifluoride piperazine complex, amine complexes of boron trichloride, phosphorus pentafluoride, arsenic pentafluoride, antimony pentafluoride, boron tetrafluoride amine salt, and metal fluorinated borate such as zinc fluoride, and these may be used alone or in combination of two or more. Furthermore, phenolic resins such as resol-type and novolac-type phenolic resins may also be used. Examples of phenolic resins include alkyl-substituted phenols such as phenol, biphenol, and cresol; cyclic alkyl-modified phenols such as terpene and dicyclopentadiene; those having a functional group containing a heteroatom such as a nitro group or an amino group; and those having a skeleton such as naphthalene or anthracene.

[0096] In addition to the above-mentioned thermosetting resin, a curing accelerator, a flexible component, an inorganic filler, and a flame retardant may be added as needed.

[0097] Known materials can be used as the elastic component. For example, various synthetic rubbers such as acrylic rubber, acrylonitrile butadiene rubber, and carboxyl-containing acrylonitrile butadiene rubber, rubber-modified high-molecular-weight compounds, modified polyimides, modified polyamide-imides, polyurethane resins, polyester resins, polyurethane polyester resins, polyvinyl butyral resins, polyvinyl acetoacetal resins, and phenoxy resins can be used. These components can be used alone or in combination of two or more.

[0098] Known inorganic fillers can be used, such as silica, alumina, silicon nitride aluminum hydroxide, magnesium hydroxide, talc, clay, etc. These fillers can be used alone or in combination of two or more.

[0099] Known flame retardants can be used. Examples include phosphorus-containing compounds, nitrogen-containing compounds, and inorganic flame retardant compounds. Specific examples include phosphorus-containing compounds such as phosphate esters (e.g., trimethyl phosphate, triethyl phosphate, tributyl phosphate, tri-2-ethylhexyl phosphate, tributoxyethyl phosphate, triphenyl phosphate, tricresyl phosphate, and trixylenyl phosphate); ammonium polyphosphate, polyphosphoric acid amide, red phosphorus, guanidine phosphate, and condensed phosphate ester compounds (e.g., dialkylhydroxymethylphosphonate); nitrogen-containing compounds (e.g., melamine); and inorganic flame retardant compounds (e.g., aluminum hydroxide, magnesium hydroxide, zinc borate, and calcium borate). These components can be used alone or in combination of two or more.

[0100] The thickness of the adhesive layer after curing is preferably 1 μm or more and 100 μm or less, more preferably 5 μm or more and 80 μm or less, and even more preferably 10 μm or more and 70 μm or less.

[0101] After the adhesive layer is cured, the dielectric constant at a frequency of 5 GHz is preferably 3.5 or less and the dielectric dissipation factor is 0.01 or less. Furthermore, the dielectric constant is more preferably 3.5 or less and the dielectric dissipation factor is 0.005 or less. A dielectric constant of 3.5 or less and a dielectric dissipation factor of 0.01 or less can be suitably used in printed circuit board-related products, which have strict electrical property requirements.

[0102] [Printed wiring board (P2)] The epoxy glass cloth laminate used in the present invention is a plate-shaped insulating material obtained by thermally curing prepregs, a composite material formed by semi-curing glass cloth impregnated with epoxy resin, either alone or laminated to a desired thickness. A printed wiring board (P2) using this insulating material can be manufactured using known techniques. For example, copper foil can be attached to one or both sides simultaneously with the thermal curing process, followed by resist etching to form a wiring pattern. A single- or double-sided printed wiring board (P2) can be obtained by drilling or lasering holes and providing conductivity through via plating into the holes to form wiring in the thickness direction. Furthermore, the printed wiring board (P2) used in the present invention can also be multilayered by thermocompression bonding printed wiring boards to one or both sides of the prepreg in a semi-cured state as an adhesive layer and then curing the printed wiring board. Thickness-wise wiring may also be formed by drilling through-holes after the multilayered printed wiring board (P2) is manufactured, and then electrically connecting the through-holes with plating or conductive resin. As an insulating material for the printed wiring board (P2), the epoxy glass cloth laminate is a general-purpose material that is both flame retardant and low conductive, and is most suitable because it has good electrical insulation stability and flatness.

[0103] [High frequency multilayer printed circuit board] The high-frequency multilayer printed circuit board of the present invention can be manufactured by laminating, via an adhesive layer having low dielectric properties, a printed wiring board (P1) formed with an insulating layer made of a resin composition containing a PAS-based resin as a main component on a printed wiring board (P2) having at least an insulating layer formed of an epoxy glass cloth laminate.

[0104] [Millimeter-wave radar, antenna, server board] The high-frequency multilayer printed circuit board of the present invention is ideal as a substrate for millimeter-wave radar, antenna base stations, and servers that use high frequencies, and has the advantage of being able to be miniaturized and have high communication speeds due to its low transmission loss, making it ideal for use as an antenna for automotive millimeter-wave radar and 5G smartphones. [Example]

[0105] Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.

[0106] [Example 1] <Manufacturing of printed wiring boards (P1)> A mixture was obtained by uniformly mixing 84.5 mass% of polyphenylene sulfide resin (DIC Corporation, linear type, melting point 280°C, melt viscosity (V6) at 300°C 110 Pa·s) into polyarylene sulfide resin (A), 15 mass% of polyphenylene ether resin (Mitsubishi Engineering Plastics, poly(2,6-dimethyl-1,4-phenylene ether), glass transition temperature 210°C) into thermoplastic resin (B) and 0.5 mass% of 3-glycidoxypropyltriethoxysilane as a silane coupling agent in a tumbler.

[0107] The polyphenylene sulfide resin has a carboxyl group at the molecular end. Hereinafter, polyphenylene sulfide resin will be referred to as "PPS" and 3-glycidoxypropyltriethoxysilane will be referred to as "silane coupling agent."

[0108] The mixture obtained above was then fed into a vented twin-screw extruder (manufactured by The Japan Steel Works, Ltd., "TEX-30α"), and melt-extruded under the conditions of a discharge rate of 20 kg / hr, a screw rotation speed of 300 rpm, a cylinder temperature setting on the raw material supply port side of 200°C, other cylinder temperatures of 280 to 320°C, and a resin temperature in the strand die of about 300°C. The mixture was discharged in the form of a strand, cooled with water at 30°C, and then cut to produce a resin composition.

[0109] The resulting resin composition was dried at 140°C for 3 hours, then loaded into a full-flight screw single-screw extruder and melted at 280-310°C. The molten resin composition was extruded through a T-die and then cooled in close contact with a chill roll set at 40°C to produce an unstretched sheet. The unstretched sheet was then biaxially stretched 3.0x3.0 times at 100°C using a batch-type biaxial stretching machine (manufactured by Imoto Manufacturing Co., Ltd.) to produce a film with a thickness of 50 μm. The resulting film was then fixed to a mold and heat-set in an oven at 275°C to produce a biaxially stretched film.

[0110] A copper layer with a thickness of 12 μm was formed on the obtained biaxially stretched film by double-sided sputter plating to obtain a copper-clad laminate. Furthermore, a wiring pattern was formed on the copper layer by resist etching to obtain a printed wiring board (P1).

[0111] <Manufacturing of printed wiring boards (P2)> Next, a wiring pattern was formed by resist etching on an epoxy glass cloth laminate (manufactured by Sanhayato, substrate thickness 1.6 mm, copper foil thickness 35 μm) with copper foil attached to both sides, to obtain a printed wiring board (P2).

[0112] <Manufacturing of multilayer printed circuit boards> A multilayer printed circuit board was manufactured by stacking a printed wiring board (P1), a bonding sheet (manufactured by Nikkan Industries Co., Ltd., "NIKAFLEX SAFY", thickness 50 μm, relative dielectric constant 3.0, dielectric dissipation factor 0.005), and a printed wiring board (P2) in that order, and then heat treating them in a vacuum press (160°C, 60 minutes, 4 MPa).

[0113] [Example 2] A multilayer printed circuit board was produced in the same manner as in Example 1, except that the PPS resin (A) (MA520) was 89.5% by mass and the thermoplastic resin (B) contained 10% by mass of a polyethersulfone resin (manufactured by BASF Ltd., glass transition temperature 225°C, hereinafter sometimes referred to as "PES").

[0114] [Example 3] A multilayer printed circuit board was produced in the same manner as in Example 1, except that a polyphenylsulfone resin (manufactured by BASF Ltd., glass transition temperature 220°C, hereinafter sometimes referred to as "PPSU") was used as the thermoplastic resin (B).

[0115] [Example 4] A multilayer printed circuit board was produced in the same manner as in Example 1, except that the PPS resin (A) (MA520) was 94.5% by mass and the thermoplastic resin (B) contained 5% by mass of polyetherimide resin (manufactured by SABIC Corporation, glass transition temperature 216°C, hereinafter sometimes referred to as "PEI").

[0116] [Example 5] A multilayer printed circuit board was produced in the same manner as in Example 1, except that a polysulfone resin (manufactured by SOLVAY Corporation, glass transition temperature 190°C, hereinafter sometimes referred to as "PSU") was used as the thermoplastic resin (B).

[0117] [Example 6] A multilayer printed circuit board was produced in the same manner as in Example 1, except that a modified fluorine-based resin having a functional group (hereinafter sometimes referred to as "modified PFA resin"; "EA-2000" manufactured by AGC Inc., melting point 300°C) was used as the thermoplastic resin (B).

[0118] [Example 7] A multilayer printed circuit board was produced in the same manner as in Example 1, except that the PPS resin (A) was 74.5% by mass, and the thermoplastic resin (B) was 10% by mass of PPE resin (glass transition temperature 210°C) and 15% by mass of modified PFA resin (melting point 300°C).

[0119] [Example 8] A multilayer printed circuit board was produced in the same manner as in Example 1, except that the PPS resin (A) was 85% by mass, the thermoplastic resin (B) was 15% by mass of PPE resin (glass transition temperature 210°C), and no silane coupling agent was added.

[0120] [Example 9] A multilayer printed circuit board was produced in the same manner as in Example 1, except that the PPS resin (A) was 82.5% by mass, the thermoplastic resin (B) was 15% by mass of modified PFA resin (melting point 300°C), the modified elastomer (C) was 2% by mass of Bondfast 7L (manufactured by Sumitomo Chemical Co., Ltd., ethylene / glycidyl methacrylate / methyl acrylate = 70 / 3 / 27 (mass%), hereinafter sometimes referred to as "BF7L"), and the silane coupling agent was 0.5% by mass.

[0121] [Example 10] A multilayer printed circuit board was produced in the same manner as in Example 1, except that the PPS resin (A) (MA520) was 94.5% by mass and the thermoplastic resin (B) contained 5% by mass of polycarbonate resin (manufactured by Mitsubishi Engineering Plastics Chemical Co., Ltd., glass transition temperature 145°C, hereinafter sometimes referred to as "PC").

[0122] (Comparative Example 1) A multilayer printed circuit board was produced in the same manner as in Example 1, except that only the PPS resin (A) was charged into a vented twin-screw extruder (manufactured by The Japan Steel Works, Ltd., "TEX-30α").

[0123] (Comparative Example 2) A multilayer printed circuit board was produced in the same manner as in Example 1, except that 84.5% by mass of PPS resin was used, 15% by mass of general-purpose polystyrene resin (manufactured by DIC Corporation, glass transition temperature 100°C, hereinafter sometimes referred to as "GPPS") was used as the thermoplastic resin (B), and 0.5% by mass of a silane coupling agent.

[0124] (Comparative Example 3) A multilayer printed circuit board was produced in the same manner as in Example 1, except that an epoxy glass cloth prepreg (manufactured by Risho Kogyo Co., Ltd., substrate thickness 50 μm) was used for the low dielectric adhesive layer.

[0125] [evaluation] 1. Dielectric properties of printed wiring board (P1) The dielectric constant and dielectric loss tangent were measured based on the cavity resonance method specified in JIS C 2565:1992. Specifically, a strip of 3 mm width x 150 mm length was prepared from an insulating layer made of a low-dielectric material that constitutes the printed wiring board (P1). The prepared strip was then left to stand for 24 hours in an environment of 23°C and 50% RH, after which the dielectric constant at a frequency of 5 GHz was measured by the cavity resonance method using an ADMS010c series (manufactured by AET Corporation).

[0126] 2. Adhesion A sample measuring 10 mm wide x 70 mm long was cut out from the laminate of the insulating layer and adhesive layer or the printed wiring board (P1) and prepreg that constitutes the printed wiring board (P1), and the test was carried out based on the test method specified in JIS K6854: 1999. The adhesion strength between the insulating layer and adhesive layer or between the insulating layer and prepreg was measured and evaluated according to the following criteria. ◎;5N / cm or more ○: 4N / cm or more and less than 5N / cm ×: Less than 4N / cm

[0127] 3. Transmission loss A microstrip line was created on a printed wiring board (P1), and the transmission loss at 50 GHz was evaluated using a probe method with a network analyzer (Keysight Technologies). ◎: Less than 7dB / 100mm ○: Less than 8dB / 100mm ×: 8dB / 100mm or more

[0128] 4.Heat resistance A multilayer printed circuit board is heated to 260°C for 30 minutes, and the swelling and peeling of the board are evaluated. 〇: No swelling or peeling ×: Blisters or peeling

[0129] 5. Embeddedness A 30 μm thick concave-convex circuit pattern was created on the printed wiring board (P2), and after creating a multilayer printed circuit board, the embedding properties of the adhesive layer and prepreg were evaluated by cross-sectional observation. ○: Filled without gaps. ×: Insufficient filling, resulting in voids or surface irregularities

[0130] [Table 1] *PAS: Polyarylene sulfide resin PPE: Polyphenylene ether resin PES; Polyethersulfone resin PPSU; Polyphenylsulfone resin PEI; Polyetherimide resin PSU: Polysulfone resin Modified PFA; Modified perfluoroalkoxyalkane PC; Polycarbonate resin BS: Bonding sheet

[0131] [Table 2]

[0132] [Table 3] *GPPS: General-purpose polystyrene resin PP; prepreg [Explanation of symbols]

[0133] a: Resin insulation layer b: Adhesive layer c: Core insulation layer d: copper layer

Claims

1. A high frequency multilayer printed circuit board in which a low dielectric adhesive layer and a printed wiring board (P1) having an insulating layer made of a low dielectric material are laminated in this order on one side of a printed wiring board (P2) having an insulating layer formed of at least an epoxy glass cloth laminate, the low dielectric material is a resin composition containing a polyarylene sulfide resin (A) and a thermoplastic resin (B) other than a polyarylene sulfide resin, the thermoplastic resin having a glass transition temperature of 140°C or higher or a melting point of 230°C or higher; 1. A multilayer printed circuit board for high frequency use, wherein the low dielectric adhesive layer is a thermosetting resin layer containing a styrene-based elastomer.

2. 2. The high-frequency multilayer printed circuit board according to claim 1, wherein the thermoplastic resin (B) other than the polyarylene sulfide resin having a glass transition temperature of 140° C. or higher or a melting point of 230° C. or higher is at least one selected from the group consisting of polycarbonate resin, polyphenylene ether resin, polyethersulfone resin, polyphenylsulfone resin, polyetherimide resin, polysulfone resin, and fluorine-based resin.

3. 3. A high frequency multilayer printed circuit board according to claim 1, wherein the dielectric constant of said low dielectric material is 3.3 or less.

4. 3. The high frequency multilayer printed circuit board according to claim 1, further comprising a modified elastomer (C) in which a reactive group is added to a resin composition of a low dielectric material.

5. 5. The high frequency multilayer printed circuit board according to claim 4, wherein the modified elastomer (C) comprises an olefin polymer having at least a functional group selected from the group consisting of an epoxy group and an acid anhydride group.

6. 5. The high-frequency multilayer printed circuit board according to claim 4, wherein the modified elastomer (C) is contained in an amount of 1 to 15 mass% relative to a total of 100 mass% of the polyarylene sulfide-based resin (A), the thermoplastic resin (B), and the modified elastomer (C).

7. 5. The high frequency multilayer printed circuit board according to claim 4, wherein the α-olefin content of the modified elastomer (C) is 50 to 95% by mass based on the total mass of the modified elastomer.

8. 3. The high frequency multilayer printed circuit board according to claim 1, further comprising 0.01 to 5 mass % of a silane coupling agent (D) having at least one functional group selected from an epoxy group, an amino group, and an isocyanate group.

9. A millimeter wave radar and antenna using the high frequency multilayer printed circuit board according to claim 1 or 2.

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