adhesive composition

Abstract

Provided is an adhesive composition that makes it possible to prevent resin flow on the occasion of thermocompression bonding by controlling mechanical characteristics, that exhibits suitable electrical characteristics, and whereby it is possible to form an adhesive layer having suitable adhesion.　The adhesive composition contains at least an inorganic filler and a resin composition including a styrene elastomer. The content of the inorganic filler is 1-180 parts by mass with respect to 100 parts by mass of the resin composition. The inorganic filler has a plate-like or scale-like shape. An adhesive layer obtained by curing the adhesive composition has a dielectric constant of 3.5 or less at a frequency of 28 GHz. The dielectric loss tangent of the adhesive layer at a frequency of 28 GHz is 0.005 or less.

Description

[Technical Field]

[0001] The present invention relates to an adhesive composition, and more particularly to an adhesive composition that can be used for bonding electronic components and the like. [Background technology]

[0002] BACKGROUND ART As electronic devices become smaller and lighter, the adhesive applications for electronic components and the like are becoming more diverse, and the demand for laminates with an adhesive layer is increasing. Furthermore, flexible printed circuit boards (hereinafter referred to as FPCs), which are one type of electronic component, are required to process large amounts of data at high speed, and progress is being made in supporting high frequencies. With the practical application of 5G, improvements in communication speeds and frequencies are predicted, requiring the realization of excellent low transmission loss and the stability of large-capacity communication. Accordingly, progress is currently being made in the development of low-dielectric materials for FPCs and adhesives that make up the adhesive layer.

[0003] In order to meet the demand for high adhesiveness while maintaining good electrical properties, a laminate has been proposed that uses an adhesive composition containing a carboxyl group-containing styrene-based elastomer (A) and an epoxy resin (B), and that comprises an adhesive layer made of the adhesive composition and a substrate film (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2016 / 017473 Summary of the Invention [Problem to be solved by the invention]

[0005] The manufacturing process for printed wiring boards involves a thermocompression bonding process, but if the adhesive has poor mechanical properties, it may not be possible to bond the board to the specified thickness or size. For example, since the adhesive is soft, resin flow may occur during thermocompression bonding, or problems such as deformation may occur during thermocompression bonding due to a large coefficient of thermal expansion (CTE). When an inorganic filler is added to prevent resin flow, problems such as deterioration of the electrical properties of the adhesive layer or a decrease in the adhesion of the adhesive layer may occur. Therefore, it is desired to provide a laminate with an adhesive layer that can prevent resin flow during thermocompression bonding, exhibits good electrical properties, and has good adhesion between the adhesive layer and the base film by controlling mechanical properties.

[0006] An object of the present invention is to provide an adhesive composition that can prevent resin flow during thermocompression bonding, exhibits good electrical properties, and can form an adhesive layer with good adhesion by controlling mechanical properties.

Means for Solving the Problems

[0007] As a result of intensive studies to solve the above problems, the present inventors have found that the above problems can be solved by adding a specific inorganic filler to a styrene-based elastomer, and have completed the present invention.

[0008] The present invention includes the following aspects. (1) An adhesive composition containing a resin composition containing at least a styrene-based elastomer and an inorganic filler, wherein the content of the inorganic filler is 1 to 180 parts by mass with respect to 100 parts by mass of the resin composition, the inorganic filler has a plate-like or flaky shape, and the relative permittivity of the adhesive layer formed by curing the adhesive composition at a frequency of 28 GHz is 3.5 or less, and the dielectric loss tangent of the adhesive layer at a frequency of 28 GHz is 0.005 or less. An adhesive composition. (2) The adhesive composition according to (1), wherein the aspect ratio of the inorganic filler is 5 to 500 or less. (3) The adhesive composition according to (1) or (2), wherein the average particle size of the inorganic filler is 3.0 μm or less. The adhesive composition according to any one of (1) to (3), wherein the inorganic filler contains at least one of a silicon-based inorganic filler and boron nitride. The adhesive composition according to any one of (1) to (4), wherein the silicon-based inorganic filler contains at least one of mica and talc. The adhesive composition according to any one of (1) to (5), wherein the styrene-based elastomer is a styrene-based elastomer containing a carboxy group. The adhesive composition according to any one of (1) to (5), wherein the styrene-based elastomer is a styrene-based elastomer containing an amino group. The adhesive composition according to any one of (1) to (7), wherein the resin composition contains an epoxy resin. The adhesive composition according to (8), wherein the content of the epoxy resin is 1 to 25 parts by mass with respect to 100 parts by mass of the resin composition. The adhesive composition according to any one of (1) to (9), wherein the storage elastic modulus of the adhesive layer before curing of the adhesive composition at 150 °C is 1.0E+5 Pa or more. The adhesive composition according to any one of (1) to (10), wherein the coefficient of thermal expansion (CTE) of the adhesive layer obtained by curing the adhesive composition is 500 ppm / K or less. (12) A base film, A laminate having an adhesive layer made of the adhesive composition according to any one of (1) to (10). The laminate according to (12), wherein the base film contains a polyether ether ketone (PEEK) resin. An adhesive layer-attached coverlay film including the laminate according to (12) or (13). A copper-clad laminate including the laminate according to (12) or (13). A printed wiring board including the laminate according to (12) or (13). A shield film including the laminate according to (12) or (13). A printed wiring board with a shield film including the laminate according to (12) or (13).

Advantages of the Invention

[0009] According to the present invention, by controlling the mechanical properties, it is possible to prevent resin flow during thermocompression bonding, exhibit good electrical properties, and form an adhesive layer with good adhesion, thereby providing an adhesive composition.

Embodiments for Carrying Out the Invention

[0010] Hereinafter, the adhesive composition of the present invention, a laminate including an adhesive layer made of the adhesive composition, and a component related to an electronic component including the laminate will be described in detail. However, the description of the constituent elements described below is an example as one embodiment of the present invention and is not limited to these contents.

[0011] (Adhesive Composition) The adhesive composition of the present invention contains at least a resin composition containing a styrene-based elastomer and an inorganic filler. The inorganic filler contained in the adhesive composition of the present invention has a plate-like or scaly shape. The content of the inorganic filler contained in the adhesive composition of the present invention is 1 to 180 parts by mass with respect to 100 parts by mass of the resin composition. The relative permittivity of the adhesive layer formed by curing the adhesive composition of the present invention at a frequency of 28 GHz is 3.5 or less, and the dielectric loss tangent of the adhesive layer at a frequency of 28 GHz is 0.005 or less. In addition to the resin composition and the inorganic filler, the adhesive composition may contain other components as necessary.

[0012] <Resin Composition> The resin composition according to the present invention contains at least a styrene-based elastomer. Among the styrene-based elastomers, it is preferably to include a styrene-based elastomer containing a carboxy group or a styrene-based elastomer containing an amino group. The resin composition can contain an epoxy resin. The resin composition may contain other resin components other than the styrene-based elastomer and the epoxy resin as necessary.

[0013] <<Styrenic elastomer>> Since styrenic elastomers do not contain highly polar bonding groups, they also have excellent electrical properties. Due to the cohesive force caused by the interaction between the structures of styrene and the ease of adjusting the molecular weight, they are resins that can adjust flexibility and adhesion. Also, by modification, the dispersibility and adhesion of inorganic fillers can be improved. Styrenic elastomers refer to copolymers mainly composed of block and random structures of conjugated diene compounds and aromatic vinyl compounds, as well as their hydrogenated products. Examples of aromatic vinyl compounds include styrene, t-butylstyrene, α-methylstyrene, divinylbenzene, 1,1-diphenylethylene, N,N-diethyl-p-aminoethylstyrene, vinyltoluene, etc. Examples of conjugated diene compounds include butadiene, isoprene, 1,3-pentadiene, 2,3-dimethyl-1,3-butadiene, etc. Specific examples of styrenic elastomers include styrene-butadiene block copolymers, styrene-ethylene propylene block copolymers, styrene-butadiene-styrene block copolymers, styrene-isoprene-styrene block copolymers, styrene-ethylene butylene-styrene block copolymers, and styrene-ethylene propylene-styrene block copolymers, etc.

[0014] These styrenic elastomers may be used alone or in combination of two or more. Among the above copolymers, from the viewpoints of adhesiveness and electrical properties, styrene-ethylene-butylene-styrene block copolymer and styrene-ethylene-propylene-styrene block copolymer are preferred. Further, the mass ratio of styrene / ethylene-butylene in the styrene-ethylene-butylene-styrene block copolymer and the mass ratio of styrene / ethylene-propylene in the styrene-ethylene-propylene-styrene block copolymer are preferably 10 / 90 to 50 / 50, and more preferably 20 / 80 to 40 / 60. If the mass ratio is within this range, an adhesive composition having excellent adhesion properties can be obtained.

[0015] The content of the styrenic elastomer is preferably 10.0 parts by mass to 99.0 parts by mass with respect to 100 parts by mass of the solid content of the resin composition.

[0016] <<<Styrenic elastomer containing a carboxy group>>> The styrenic elastomer containing a carboxy group is effective as a component having high adhesion, capable of imparting flexibility to the cured product, and providing good electrical properties. Since the styrenic elastomer containing a carboxy group is contained in the adhesive composition, even for adherends such as a base film or a metal foil having good electrical properties and low polarity, a flexible adhesive composition can sufficiently follow the surface of the adherend, so that the highly polar carboxy group can exhibit adhesiveness, thereby improving the adhesiveness of the adhesive layer. Further, since the styrenic elastomer containing a carboxy group is reactive, the heat resistance and chemical resistance of the adhesive layer are also improved by epoxy curing. In addition, the dispersibility of the inorganic filler in the dispersion is improved by containing a carboxy group. The styrenic elastomer containing a carboxy group is a copolymer mainly having a block and random structure of a conjugated diene compound and an aromatic vinyl compound, and a hydrogenated product thereof, which is modified with an unsaturated carboxylic acid. The types of aromatic vinyl compounds and conjugated diene compounds and specific examples of styrene-based elastomers are as described above in the section "Styrene-based elastomers."

[0017] The modification of a carboxyl group-containing styrene elastomer can be carried out, for example, by copolymerizing an unsaturated carboxylic acid during polymerization of the styrene elastomer, or by heating and kneading the styrene elastomer and the unsaturated carboxylic acid in the presence of an organic peroxide. Examples of the unsaturated carboxylic acid include acrylic acid, methacrylic acid, maleic acid, itaconic acid, fumaric acid, maleic anhydride, and itaconic anhydride. The amount of modification with the unsaturated carboxylic acid is preferably 0.1 to 10% by mass. The acid value of the carboxyl group-containing styrene-based elastomer is preferably 0.1 to 30 mgKOH / g, more preferably 0.5 to 25 mgKOH / g, and even more preferably 0.5 to 5 mgKOH / g. When this acid value is 0.1 mgKOH / g or more, the dispersibility of the inorganic filler is improved. When the acid value is 0.5 mgKOH / g or more, the adhesive composition is cured sufficiently, and good adhesion and heat resistance are obtained. On the other hand, when the acid value is 30 mgKOH / g or less, the cohesive force of the adhesive composition is suppressed, resulting in excellent adhesion and excellent electrical properties. When the acid value is 5 mgKOH / g or less, the adhesion to the PEEK substrate is improved.

[0018] The weight-average molecular weight of the carboxyl group-containing styrene elastomer is preferably 10,000 to 500,000, more preferably 30,000 to 300,000, and even more preferably 50,000 to 200,000. If the weight-average molecular weight is equal to or greater than the lower limit, excellent adhesiveness can be exhibited, and the coatability when dissolved in a solvent and applied is also improved. If the weight-average molecular weight is equal to or less than the upper limit, compatibility with epoxy resins is improved. If the weight average molecular weight is within the above range, the mechanical properties can be controlled within an appropriate range, and both prevention of resin flow and dispersibility of the inorganic filler in the dispersion can be achieved. The weight average molecular weight is a value obtained by converting the molecular weight measured by gel permeation chromatography (hereinafter also referred to as "GPC") into polystyrene equivalent.

[0019] The content of the styrene elastomer containing a carboxy group is preferably 10.0 to 99.0 parts by mass with respect to 100 parts by mass of the solid content of the resin composition. If the content is within the above range, an adhesive composition having excellent adhesion properties can be obtained. More preferably, it is 20 to 49 parts by mass with respect to 100 parts by mass of the solid content of the resin composition. If the content is within the above range, the mechanical properties can be controlled within an appropriate range, and both prevention of resin flow and dispersibility of the inorganic filler in the dispersion can be achieved.

[0020] <<<Styrene elastomer containing an amino group>>> The inclusion of a styrene elastomer containing an amino group in the adhesive composition increases the reactivity and improves the adhesion of the adhesive layer. Further, since the styrene elastomer containing an amino group is reactive, the heat resistance and chemical resistance of the adhesive layer are also improved by epoxy curing. The adhesion to metals is improved because it contains an amino group. Also, because it contains an amino group, it has high reactivity with epoxy resins and can be cured before the resin flows out, effectively preventing resin flow. The styrene elastomer containing an amino group is a copolymer mainly composed of a block and random structure of a conjugated diene compound and an aromatic vinyl compound, and a hydrogenated product thereof, which is amine-modified. The types of the aromatic vinyl compound and the conjugated diene compound and specific examples of the styrene elastomer are as described in the above <<Styrene elastomer>> column.

[0021] The method for amine-modifying a styrene-based elastomer is not particularly limited, and any known method can be used. Examples of such methods include a method of amine-modifying a (hydrogenated) block copolymer by polymerizing it using a polymerization initiator having an amino group, a method of amine-modifying a (hydrogenated) copolymer by using an unsaturated monomer having an amino group as a raw material for copolymerization, and a method of amine-modifying a styrene-based elastomer containing a carboxy group by reacting it with an amine modifier having two or more amino groups to form an amide structure or an imide structure.

[0022] The weight-average molecular weight of the amino group-containing styrene elastomer is preferably 10,000 to 500,000, more preferably 30,000 to 300,000, and even more preferably 50,000 to 200,000. If the weight-average molecular weight is equal to or greater than the lower limit, excellent adhesive properties can be exhibited, and the coatability when dissolved in a solvent and coated also improves. If the weight-average molecular weight is equal to or less than the upper limit, compatibility with epoxy resins improves. If the weight average molecular weight is within the above range, the mechanical properties can be controlled within an appropriate range, and both prevention of resin flow and dispersibility of the inorganic filler in the dispersion can be achieved.

[0023] The content of the amino group-containing styrene-based elastomer is preferably 10.0 to 99.0 parts by mass per 100 parts by mass of the solid content of the resin composition. It is more preferably 20 to 49 parts by mass per 100 parts by mass of the solid content of the resin composition. A content of 10.0 to 99.0 parts by mass can provide an adhesive composition with excellent adhesive properties. A content of 20 to 49 parts by mass can control the mechanical properties within an appropriate range, preventing resin flow and achieving good dispersibility of the inorganic filler in the dispersion.

[0024] By mixing unmodified styrene elastomers with modified styrene elastomers, it is possible to adjust the hardness and control the MFR while maintaining adhesiveness.

[0025] <<Epoxy resin>> The epoxy resin reacts with the carboxyl groups in the styrene-based elastomer containing the above carboxyl groups or the amino groups in the styrene-based elastomer containing the above amino groups, and is a component that exhibits high adhesiveness to the adherend and heat resistance of the cured adhesive.

[0026] Examples of the epoxy resin include bisphenol A type epoxy resin, bisphenol F type epoxy resin, or hydrogenated products thereof; glycidyl ester type epoxy resins such as diglycidyl phthalate, diglycidyl isophthalate, diglycidyl terephthalate, glycidyl p-hydroxybenzoate, diglycidyl tetrahydrophthalate, diglycidyl succinate, diglycidyl adipate, diglycidyl sebacate, triglycidyl trimellitate; glycidyl ether type epoxy resins such as ethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, 1,4-butanediol diglycidyl ether, 1,6-hexanediol diglycidyl ether, trimethylolpropane triglycidyl ether, pentaerythritol tetraglycidyl ether, tetraphenyl glycidyl ether ethane, triphenyl glycidyl ether ethane, polyglycidyl ether of sorbitol, polyglycidyl ether of polyglycerol; glycidyl amine type epoxy resins such as triglycidyl isocyanurate, tetraglycidyl diaminodiphenylmethane; linear aliphatic epoxy resins such as epoxidized polybutadiene, epoxidized soybean oil, etc., but are not limited thereto. Also, novolak type epoxy resins such as xylene structure-containing novolak epoxy resin, naphthol novolak type epoxy resin, phenol novolak epoxy resin, o-cresol novolak epoxy resin, bisphenol A novolak epoxy resin can also be used.

[0027] Furthermore, as examples of the epoxy resin, brominated bisphenol A type epoxy resin, phosphorus-containing epoxy resin, fluorine-containing epoxy resin, dicyclopentadiene skeleton-containing epoxy resin, naphthalene skeleton-containing epoxy resin, anthracene type epoxy resin, tertiary butyl catechol type epoxy resin, triphenylmethane type epoxy resin, tetraphenylethane type epoxy resin, biphenyl type epoxy resin, bisphenol S type epoxy resin, etc. can be used. These epoxy resins may be used alone or in combination of two or more. Among the above epoxy resins, an epoxy resin having no hydroxyl group is preferable because an adhesive composition excellent in electrical characteristics can be obtained and the compatibility with a styrene-based elastomer is good. In particular, novolac epoxy resin and an epoxy resin having the following structure are more preferable because they are epoxy resins having a moderately flexible skeleton, so that the cured product is less likely to cause brittle fracture, the stability of the performance of the cured product of the adhesive composition against long-term use is improved, and the number of functional groups is high, so that the heat resistance is also improved. It is more preferable that it is an epoxy compound of a styrene-butadiene block copolymer. In the epoxy compound of a styrene-butadiene block copolymer, since an unsaturated bond other than an aromatic ring such as an olefin skeleton or a vinyl group is involved in the reaction of the epoxy structure, the reaction rate can be accelerated and the crosslink density can be increased. As a result, heat resistance and chemical resistance can be improved even with a small blending amount. In addition, the epoxy compound of a styrene-butadiene block copolymer has a large molecular weight and contains an epoxy group, so it acts like a dispersant and further improves the dispersibility of the inorganic filler. As the epoxy compound of a styrene-butadiene block copolymer, commercially available epoxy compounds can also be used. For example, Celoxide 2021P, Celoxide 2081, Celoxide 2000 (manufactured by Daicel Corporation), Epolead GT401, Epolead PB3600, Epolead PB4700 (manufactured by Daicel Corporation), Epoflend AT501, Epoflend CT310 (manufactured by Daicel Corporation) can be mentioned.

[0028]

Chemical formula

[0029] In addition, epoxy resins having an amino group can shorten the curing time and lower the curing temperature due to the catalytic action of the amino group, so the workability can be improved. Also, since it contains an amino group, the adhesion to the metal layer is improved. Particularly, it is more preferable that the epoxy resin is a glycidylamine-type epoxy resin. Since glycidylamine-type epoxy resins are polyfunctional, they can be cured with a small amount. Since they contain an amine in the molecular skeleton, they have good compatibility with amino group-containing styrene-based elastomers and also have a reaction-promoting effect. Also, since they contain an amino group, the adhesion to the metal layer can be improved. Specific examples of glycidylamine-type epoxy resins include, for example, as tetraglycidyl diaminodiphenylmethane, "jER604" manufactured by Mitsubishi Chemical Corporation, "Sumiepoxy ELM434" manufactured by Sumitomo Chemical Co., Ltd., "Araldite MY720", "Araldite MY721", "Araldite MY9512", "Araldite MY9612", "Araldite MY9634", "Araldite MY9663" manufactured by Huntsman Advanced Materials Corporation, "TETRAD-X", "TETRAD-C" manufactured by Mitsubishi Gas Chemical Company, Inc., and the like.

[0030] As the epoxy resin used in the present invention, those having two or more epoxy groups in one molecule are preferable. This is because a crosslinked structure can be formed by the reaction with the carboxy group-containing styrene-based elastomer, and high heat resistance can be exhibited. Further, when an epoxy resin having two or more epoxy groups is used, the degree of crosslinking with the carboxy group-containing styrene-based elastomer is sufficient, and sufficient heat resistance can be obtained.

[0031] The content of the above epoxy resin is preferably 1 to 25 parts by mass with respect to 100 parts by mass of the resin composition. If the content of the above epoxy resin is equal to or more than the above lower limit value, the adhesive composition can be sufficiently cured and good heat resistance and chemical resistance can be ensured. On the other hand, if the content of the epoxy resin is large, the adhesiveness decreases. Therefore, if it is equal to or less than the above upper limit value, good adhesiveness can be ensured.

[0032] The softening point or melting point of the above epoxy resin is preferably 90°C or lower. When the softening point or melting point of the epoxy resin is 90°C or lower, the glass transition point of the adhesive composition can be lowered, the elastic modulus in the high temperature range of the uncured adhesive composition can be lowered, and the elastic modulus in the normal temperature range (room temperature) of the cured adhesive composition can be increased. Further, it is preferable that the epoxy resin is dissolved at the reaction temperature because the reaction is faster.

[0033] <<Other resin components>> In addition to the styrene-based elastomer and the epoxy resin appropriately contained as described above, the resin composition can contain other thermoplastic resins other than the styrene-based elastomer to such an extent that it does not affect the function of the adhesive composition.

[0034] Examples of the above other thermoplastic resins include phenoxy resin, polyamide resin, polyester resin, polycarbonate resin, polyphenylene oxide resin, polyurethane resin, polyacetal resin, polyethylene-based resin, polypropylene-based resin, and polyvinyl-based resin. These thermoplastic resins may be used alone or in combination of two or more.

[0035] <Inorganic filler> The inorganic filler has a plate-like or flaky shape. The content of the inorganic filler contained in the adhesive composition of the present invention is 1 to 180 parts by mass with respect to 100 parts by mass of the resin composition. It is more preferable that the content of the inorganic filler is 30 to 175 parts by mass with respect to 100 parts by mass of the resin composition. If the content of the inorganic filler is within the above range, the mechanical properties can be controlled within an appropriate range, and both prevention of resin flow and good adhesion can be achieved.

[0036] As the inorganic filler according to the present invention, as long as it has a plate-like or flaky shape, there is no particular limitation on the type, and it can be appropriately selected according to the purpose. For example, from the viewpoints of heat resistance and dielectric properties, silicon-based inorganic fillers and boron nitride are preferable. Among the silicon-based inorganic fillers, natural mica, synthetic mica, and natural talc are more preferable from the viewpoint of aspect ratio, and among them, synthetic mica is even more preferable from the viewpoint of water absorption rate. These may be used alone or in combination of two or more. In the present invention, an inorganic filler having a specific shape is contained in a specific amount in the adhesive composition, and an adhesive layer is formed from the adhesive composition. The obtained adhesive layer can prevent resin flow during thermocompression bonding, exhibits good electrical properties, and has good adhesion.

[0037] The average particle size of the inorganic filler according to the present invention is preferably 3.0 μm or less. The average particle size of the inorganic filler can be calculated, for example, by using the laser scattering method. Also, the aspect ratio of the inorganic filler is preferably 5 or more and 500 or less from the viewpoints of coefficient of thermal expansion (CTE) and film strength.

[0038] [Measurement of aspect ratio] The aspect ratio of the inorganic filler can be determined, for example, by observing using a scanning electron microscope (SEM) or a transmission electron microscope (TEM) and calculating from the average of the measured values. For example, regarding the aspect ratio of the inorganic filler present in the film (layer), after embedding the film in an epoxy resin, ion milling of the film cross-section is performed using an ion milling device to prepare a sample for cross-section observation, and the cross-section of the obtained sample is observed using a scanning electron microscope (SEM) or a transmission electron microscope (TEM), and it can be determined from the average of the measured values of the length and thickness of the inorganic filler in the plane direction.

[0039] The content of the inorganic filler in the film is preferably 1 to 50% by volume. More preferably, the content of the inorganic filler in the film is 2 to 30% by volume. If the content of the inorganic filler is at least the above lower limit, the resin flow of the adhesive layer can be prevented. If the content of the inorganic filler is 50% by volume or less, the dispersibility and heat resistance of the inorganic filler can be improved. If the content of the inorganic filler is 30% by volume or less, good adhesion can be ensured.

[0040] <Other components> In addition to the styrene-based elastomer and the inorganic filler described above, the adhesive composition can contain, as other components, for example, tackifiers, flame retardants, curing agents, curing accelerators, coupling agents, heat stabilizers, leveling agents, defoaming agents, pigments, and solvents, etc., to an extent that does not affect the function of the adhesive composition.

[0041] Examples of the above tackifiers include coumarone-indene resins, terpene resins, terpene-phenol resins, rosin resins, p-t-butylphenol-acetylene resins, phenol-formaldehyde resins, xylene-formaldehyde resins, petroleum-based hydrocarbon resins, hydrogenated hydrocarbon resins, and terepin-based resins. These tackifiers may be used alone or in combination of two or more.

[0042] The flame retardant may be either an organic flame retardant or an inorganic flame retardant. Examples of organic flame retardants include phosphorus-based flame retardants such as melamine phosphate, melamine polyphosphate, guanidine phosphate, guanidine polyphosphate, ammonium phosphate, ammonium polyphosphate, ammonium amido phosphate, ammonium amido polyphosphate, carbamate phosphate, carbamate polyphosphate, aluminum trisdiethylphosphinate, aluminum trismethylethylphosphinate, aluminum trisdiphenylphosphinate, zinc bisdiethylphosphinate, zinc bismethylethylphosphinate, zinc bisdiphenylphosphinate, titanyl bisdiethylphosphinate, titanium tetrakisdiethylphosphinate, titanyl bismethylethylphosphinate, titanium tetrakismethylethylphosphinate, titanyl bisdiphenylphosphinate, and titanium tetrakisdiphenylphosphinate; nitrogen-based flame retardants such as triazine-based compounds such as melamine, melam, and melamine cyanurate, cyanuric acid compounds, isocyanuric acid compounds, triazole-based compounds, tetrazole compounds, diazo compounds, and urea; and silicon-based flame retardants such as silicone compounds and silane compounds. Examples of inorganic flame retardants include metal hydroxides such as aluminum hydroxide, magnesium hydroxide, zirconium hydroxide, barium hydroxide, and calcium hydroxide; metal oxides such as tin oxide, aluminum oxide, magnesium oxide, zirconium oxide, zinc oxide, molybdenum oxide, and nickel oxide; zinc carbonate, magnesium carbonate, barium carbonate, zinc borate, and hydrated glass. Two or more of these flame retardants can be used in combination.

[0043] Examples of the curing agent include, but are not limited to, amine-based curing agents and acid anhydride-based curing agents. Examples of the amine-based curing agent include melamine resins such as methylated melamine resin, butylated melamine resin, and benzoguanamine resin, dicyandiamide, and 4,4'-diphenyldiaminosulfone. Examples of the acid anhydride include aromatic acid anhydrides and aliphatic acid anhydrides. These curing agents may be used alone or in combination of two or more. The content of the curing agent is preferably 0.5 to 100 parts by mass, more preferably 5 to 70 parts by mass, based on 100 parts by mass of the adhesive composition.

[0044] The above-mentioned curing accelerator is used for the purpose of accelerating the reaction between the styrene-based elastomer containing a carboxy group and the epoxy resin, and a tertiary amine-based curing accelerator, a tertiary amine salt-based curing accelerator, an imidazole-based curing accelerator, etc. can be used. By adding the above-mentioned curing accelerator, the reaction proceeds quickly, and curing can be achieved before the resin flows out, effectively preventing resin flow.

[0045] Examples of the tertiary amine-based curing accelerator include benzyldimethylamine, 2-(dimethylaminomethyl)phenol, 2,4,6-tris(dimethylaminomethyl)phenol, tetramethylguanidine, triethanolamine, N,N'-dimethylpiperazine, triethylenediamine, 1,8-diazabicyclo[5.4.0]undecene, etc.

[0046] Examples of the tertiary amine salt-based curing accelerator include formate, octylate, p-toluenesulfonate, o-phthalate, phenolate or phenol novolak resin salt of 1,8-diazabicyclo[5.4.0]undecene, and formate, octylate, p-toluenesulfonate, o-phthalate, phenolate or phenol novolak resin salt of 1,5-diazabicyclo[4.3.0]nonene, etc.

[0047] Imidazole-based curing accelerators include 2-methylimidazole, 2-undecylimidazole, 2-heptadecylimidazole, 1,2-dimethylimidazole, 2-methyl-4-ethylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, 1-benzyl-2-methylimidazole, 1-benzyl-2-phenylimidazole, 2,4-diamino-6-[2'-methylimidazolyl-(1')]ethyl-s-triazine, 2,4-diamino-6-[2' 2,4-diamino-6-[2'-ethyl-4'-methylimidazolyl-(1')]ethyl-s-triazine, 2,4-diamino-6-[2'-ethyl-4'-methylimidazolyl-(1')]ethyl-s-triazine, 2,4-diamino-6-[2'-methylimidazolyl-(1')]ethyl-s-triazine isocyanuric acid adduct, 2-phenylimidazole isocyanuric acid adduct, 2-phenyl-4,5-dihydroxymethylimidazole, 2-phenyl-4-methyl-5-hydroxymethylimidazole, etc. These curing accelerators may be used alone or in combination of two or more.

[0048] When the adhesive composition contains a curing accelerator, the content of the curing accelerator is preferably 0.05 to 10 parts by mass, and more preferably 0.1 to 5 parts by mass, per 100 parts by mass of the adhesive composition. When the content of the curing accelerator is within the above range, the reaction between the styrene-based elastomer and the epoxy resin, and the reaction between the epoxy resins themselves, can proceed easily, making it easier to ensure adhesion and heat resistance.

[0049] Examples of the coupling agent include silane-based coupling agents such as vinyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, p-styryltrimethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-acryloxypropyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, 3-ureidopropyltriethoxysilane, 3-mercaptopropylmethyldimethoxysilane, bis(triethoxysilylpropyl)tetrasulfide, 3-isocyanatopropyltriethoxysilane, and imidazole silane; titanate-based coupling agents; aluminate-based coupling agents; and zirconium-based coupling agents. These may be used alone or in combination of two or more.

[0050] Examples of the heat aging inhibitor include 2,6-di-tert-butyl-4-methylphenol, n-octadecyl-3-(3',5'-di-tert-butyl-4'-hydroxyphenyl)propionate, tetrakis[methylene-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]methane, pentaerythritol tetrakis[3-(3,5-di-t-butyl-4-hydroxyphenol], triethylene glycol-bis[3 Examples of antioxidants include phenol-based antioxidants such as 3-(3-t-butyl-5-methyl-4-hydroxyphenyl)propionate, sulfur-based antioxidants such as dilauryl-3,3'-thiodipropionate and dimyristyl-3,3'-dithiopropionate, and phosphorus-based antioxidants such as trisnonylphenyl phosphite and tris(2,4-di-tert-butylphenyl)phosphite. These antioxidants may be used alone or in combination of two or more.

[0051] <Characteristics of the adhesive layer made of the adhesive composition> The adhesive layer made of the adhesive composition of the present invention is formed by forming the adhesive composition into a film and curing it. The curing method is not particularly limited and can be appropriately selected depending on the purpose, and examples thereof include thermal curing. The thickness of the adhesive layer is not particularly limited and can be appropriately selected according to the purpose. For example, from the perspective of thinning, it is preferably 3 to 100 μm, more preferably 5 to 70 μm in order to ensure adhesion, and even more preferably 10 to 50 μm in order to more accurately control resin flow.

[0052] The relative permittivity (εr) of the adhesive layer formed by curing the adhesive composition of the present invention at a frequency of 28 GHz is 3.5 or less, and the dielectric loss tangent (tanδ) of the adhesive layer at a frequency of 28 GHz is 0.005 or less. Further, it is desirable that the relative permittivity is 3.2 or less and the dielectric loss tangent is 0.002 or less. If the relative permittivity is 3.5 or less and the dielectric loss tangent is 0.005 or less, it can be suitably used for FPC-related products with strict electrical property requirements. If the relative permittivity is 3.2 or less and the dielectric loss tangent is 0.002 or less, attenuation can be further reduced even in high-frequency transmission.

[0053] [Relative Permittivity and Dielectric Loss Tangent] The relative permittivity and dielectric loss tangent of the adhesive layer can be measured by the open resonator method under the conditions of a temperature of 23°C and a frequency of 28 GHz using a network analyzer MS46122B (manufactured by Anritsu Corporation) and an open resonator Fabry-Perot DPS-03 (manufactured by KEYCOM Corporation).

[0054] From the perspective of the adhesion strength of the laminate, the storage modulus of the adhesive layer after curing the adhesive composition of the present invention at 25°C is preferably 1.0E+8 Pa or more. Also, the storage modulus of the adhesive layer after curing the adhesive composition at 25°C is preferably 1.0E+9 Pa or less. When the storage modulus is within the above range, it is possible to maintain the adhesion strength of the laminate. The storage elastic modulus of the adhesive layer before curing of the adhesive composition of the present invention is preferably 1.0E+5 Pa or more and 1.0E+8 Pa or less from the viewpoint of adhesion. Further, it is more preferably 1.0E+5 Pa or more and 1.0E+7 Pa or less from the viewpoint of followability to the adherend surface, and even more preferably 1.0E+6 Pa or more and 1.0E+7 Pa or less from the viewpoint of resin flow. When the storage elastic modulus is within the above range, it is preferable because the mechanical properties can be controlled during thermocompression bonding and both resin flow and adhesion can be achieved.

[0055] [Storage elastic modulus (Pa)] The storage elastic modulus of the adhesive layer can be obtained, for example, for a sample composed of the adhesive layer by preparing an adhesive film with a thickness of 100 μm and measuring it according to JIS K7244 under the conditions of a measurement frequency of 1 Hz and a temperature increase rate of 5 °C / min using a viscoelasticity measuring device (RSA-G2 manufactured by TA Instruments).

[0056] The coefficient of thermal expansion (CTE) of the adhesive layer obtained by curing the adhesive composition of the present invention is preferably 500 ppm / K or less. When the coefficient of thermal expansion is below the above value, it is preferable because there is less deformation during thermocompression bonding. The measurement of the coefficient of thermal expansion can be performed, for example, by using a tensile mode with a thermomechanical analyzer [Product name: SII / / SS7100 manufactured by Hitachi High-Tech Sciences Corporation], with a load of 50 mN and a temperature increase rate of 5 °C / min. The temperature is increased from 25 °C to 250 °C at a rate of 5 °C / min, the temperature change of the dimensions is measured, and the coefficient of linear expansion is obtained from the slope in the range from 25 °C to 125 °C.

[0057] <Method for manufacturing the adhesive layer> The adhesive layer can be manufactured by forming a film of the above adhesive composition. The adhesive composition can be produced by mixing a resin composition containing at least a styrene-based elastomer, an inorganic filler, and, if necessary, other resin components and other components. The mixing method is not particularly limited as long as the adhesive composition is homogeneous. Since the adhesive composition is preferably used in the form of a solution or dispersion, a solvent is usually also used. Examples of solvents include alcohols such as methanol, ethanol, isopropyl alcohol, n-propyl alcohol, isobutyl alcohol, n-butyl alcohol, benzyl alcohol, ethylene glycol monomethyl ether, propylene glycol monomethyl ether, diethylene glycol monomethyl ether, and diacetone alcohol; ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, methyl amyl ketone, cyclohexanone, and isophorone; aromatic hydrocarbons such as toluene, xylene, ethylbenzene, and mesitylene; esters such as methyl acetate, ethyl acetate, ethylene glycol monomethyl ether acetate, and 3-methoxybutyl acetate; and aliphatic hydrocarbons such as hexane, heptane, cyclohexane, and methylcyclohexane. These solvents may be used alone or in combination of two or more. When the adhesive composition is a solution or dispersion (resin varnish) containing a solvent, it can be smoothly applied to a substrate film and an adhesive layer can be formed, and an adhesive layer of the desired thickness can be easily obtained. When the adhesive composition contains a solvent, the solid content is preferably 3 to 80% by mass, more preferably 10 to 50% by mass, from the viewpoint of workability including the formation of the adhesive layer. When the solid content is 80% by mass or less, the viscosity of the solution is appropriate, and uniform application is easy. In a more specific embodiment of the method for producing an adhesive layer, a resin varnish containing the adhesive composition and a solvent is applied to the surface of a substrate film to form a resin varnish layer, and then the solvent is removed from the resin varnish layer to form a B-stage adhesive layer. Here, the B-stage adhesive layer refers to an adhesive composition in an uncured state or a semi-cured state in which a portion of the adhesive composition has begun to cure, and refers to a state in which the curing of the adhesive composition progresses further by heating or the like. Here, the method for applying the resin varnish onto the substrate film is not particularly limited and can be appropriately selected depending on the purpose, and examples thereof include spraying, spin coating, dipping, roll coating, blade coating, doctor roll method, doctor blade method, curtain coating, slit coating, screen printing, inkjet method, and dispensing method. The adhesive layer in the B-stage state can be further subjected to heating or the like to form a cured adhesive layer.

[0058] (Laminate) The laminate of the present invention comprises a substrate film and the above-described adhesive layer on at least one surface of the substrate film.

[0059] <Base film> The substrate film used in the present invention can be selected depending on the application of the laminate. For example, when the laminate is used as a coverlay film or a copper-clad laminate (CCL), examples of the substrate film include polyimide film, polyether ether ketone film, polyphenylene sulfide film, aramid film, polyethylene naphthalate film, and liquid crystal polymer film. Among these, polyimide film, polyether ether ketone (PEEK) film, polyethylene naphthalate film, and liquid crystal polymer film are preferred from the viewpoints of adhesiveness and electrical properties.

[0060] When the laminate of the present invention is used as a bonding sheet, the base film needs to be a release film. For example, polyethylene terephthalate film, polyethylene film, polypropylene film, silicone release-treated paper, polyolefin resin-coated paper, TPX (polymethylpentene) film, and fluororesin film can be mentioned.

[0061] When the laminate of the present invention is used as a shielding film, the base film needs to be a film having electromagnetic wave shielding ability. For example, a laminate of a protective insulating layer and a metal foil can be mentioned.

[0062] (Coverlay film) As a preferred embodiment of the laminate according to the present invention, a coverlay film can be mentioned. When manufacturing an FPC, in order to protect the wiring portion, a laminate having an adhesive layer generally called a "coverlay film" is usually used. This coverlay film includes an insulating resin layer and an adhesive layer formed on the surface thereof. For example, in the coverlay film, the adhesive layer is formed on at least one surface of the base film, and it is a laminate in which peeling of the base film and the adhesive layer is generally difficult. The thickness of the base film included in the coverlay film is preferably 5 to 100 μm, more preferably 5 to 50 μm, and even more preferably 5 to 30 μm. If the thickness of the base film is below the above upper limit, the coverlay film can be made thinner. If the thickness of the base film is above the above lower limit, the design of the printed wiring board can be facilitated and the handling is also good. As a method for manufacturing a coverlay film, for example, a resin varnish containing the above adhesive composition and a solvent is applied to the surface of the above base film to form a resin varnish layer, and then the solvent is removed from the resin varnish layer, whereby a coverlay film having a B-stage adhesive layer formed thereon can be manufactured. The drying temperature when removing the solvent is preferably 40 to 250 °C, and more preferably 70 to 170 °C. Drying is performed by passing the laminate coated with the adhesive composition through a furnace where hot air drying, far-infrared heating, high-frequency induction heating, etc. are carried out. In addition, if necessary, a release film may be laminated on the surface of the adhesive layer for storage or the like. As the release film, known ones such as polyethylene terephthalate film, polyethylene film, polypropylene film, silicone release-treated paper, polyolefin resin-coated paper, TPX film, fluororesin film, etc. are used. Since the coverlay film according to the present invention uses the low-dielectric adhesive composition of the present invention, high-speed transmission of electronic devices is possible, and furthermore, the adhesion stability with electronic devices is also excellent.

[0063] (Bonding sheet) As a preferred embodiment of the laminate according to the present invention, a bonding sheet can be mentioned. The bonding sheet is one in which the above adhesive layer is formed on the surface of a release film (base film). Also, the bonding sheet may be in a form having an adhesive layer between two release films. When using the bonding sheet, the release film is peeled off and used. As the release film, the same ones as those described in the above (coverlay film) column can be used. The thickness of the base film contained in the bonding sheet is preferably 5 to 100 μm, more preferably 25 to 75 μm, and even more preferably 38 to 50 μm. If the thickness of the base film is within the above range, the production of the bonding sheet is easy and the handling is good. As a method for manufacturing the bonding sheet, for example, there is a method of applying a resin varnish containing the above adhesive composition and a solvent on the surface of a release film and drying it in the same manner as in the case of the above coverlay film. Since the bonding sheet according to the present invention uses the low-dielectric adhesive composition of the present invention, high-speed transmission of electronic devices is possible, and furthermore, the adhesion stability with electronic devices is also excellent.

[0064] (Copper-clad laminate (CCL)) As a preferred embodiment of the laminate according to the present invention, a copper-clad laminate obtained by laminating a copper foil on the adhesive layer in the laminate of the present invention can be mentioned. The copper-clad laminate has a copper foil laminated using the above laminate. For example, it is composed of a base film, an adhesive layer, and a copper foil in this order. Note that the adhesive layer and the copper foil may be formed on both sides of the base film. The adhesive composition used in the present invention is also excellent in adhesiveness to articles containing copper. Since the copper-clad laminate according to the present invention uses the low-dielectric adhesive composition of the present invention, it enables high-speed transmission in electronic devices and has excellent adhesion stability.

[0065] As a method for manufacturing a copper-clad laminate, for example, there is a method in which the adhesive layer of the above laminate and the copper foil are brought into surface contact, heat lamination is performed at 80°C to 150°C, and the adhesive layer is further cured by post-cure. The conditions for post-cure can be, for example, 100°C to 200°C for 30 minutes to 4 hours in an atmosphere of an inert gas. The copper foil is not particularly limited, and an electrolytic copper foil, a rolled copper foil, etc. can be used.

[0066] (Printed wiring board) As a preferred embodiment of the laminate according to the present invention, a printed wiring board obtained by laminating a copper wiring on the adhesive layer in the laminate of the present invention can be mentioned. The printed wiring board can be obtained by forming an electronic circuit on the above copper-clad laminate. The printed wiring board has a base film and a copper wiring laminated using the above laminate, and is composed of a base film, an adhesive layer, and a copper wiring in this order. Note that the adhesive layer and the copper wiring may be formed on both sides of the base film. For example, a printed wiring board is manufactured by attaching a coverlay film via an adhesive layer to the surface having a wiring portion using hot press or the like. Since the printed wiring board according to the present invention uses the low-dielectric adhesive composition of the present invention, it enables high-speed transmission of electronic devices and has excellent adhesion stability. As a method for manufacturing the printed wiring board according to the present invention, for example, there is a method in which the adhesive layer of the laminate is brought into contact with the copper wiring, heat lamination is performed at 80°C to 150°C, and the adhesive layer is further cured by post-curing. The conditions for post-curing can be, for example, 100°C to 200°C for 30 minutes to 4 hours. The shape of the copper wiring is not particularly limited, and appropriate shapes and the like can be selected as desired.

[0067] (Shield film) A preferred embodiment of the laminate according to the present invention includes a shield film. The shield film is a film for shielding various electronic devices in order to cut electromagnetic wave noise that affects various electronic devices such as computers, mobile phones, and analytical devices and causes malfunction. It is also called an electromagnetic wave shield film. The electromagnetic wave shield film is formed by laminating, for example, an insulating resin layer, a metal layer, and the adhesive layer of the present invention in this order. Since the shield film according to the present invention uses the low-dielectric adhesive composition of the present invention, high-speed transmission of electronic devices is possible, and furthermore, the adhesion stability with electronic devices is also excellent.

[0068] (Printed wiring board with shield film) A preferred embodiment of the laminate according to the present invention includes a printed wiring board with a shield film. The printed wiring board with a shield film is a printed wiring board having a printed circuit provided on at least one side of a substrate, on which the electromagnetic wave shield film is attached. The printed wiring board with a shield film includes, for example, a printed wiring board, an insulating film adjacent to the surface on which the printed circuit of the printed wiring board is provided, and the electromagnetic wave shield film. Since the printed wiring board with a shield film according to the present invention uses the low-dielectric adhesive composition of the present invention, it enables high-speed transmission of electronic devices and has excellent adhesion stability.

Example

[0069] The present invention will be described in more detail with reference to the following examples, but the scope of the present invention is not limited to these examples. In the following, parts and % are based on mass unless otherwise specified.

[0070] (Styrene-based elastomer containing a carboxy group) The product name "Tuftec M1913" (maleic acid-modified styrene-ethylene-butylene-styrene block copolymer) manufactured by Asahi Kasei Corporation was used. The acid value of this copolymer is 10 mgKOH / g, the styrene / ethylene-butylene ratio is 30 / 70, and the weight average molecular weight is 67,000. (Styrene-based elastomer containing a carboxy group) The product name "Tuftec M1911" (maleic acid-modified styrene-ethylene-butylene-styrene block copolymer) manufactured by Asahi Kasei Corporation was used. The acid value of this copolymer is 2 mgKOH / g, the styrene / ethylene-butylene ratio is 30 / 70, and the weight average molecular weight is 69,000. (Styrene-based elastomer not containing a carboxy group) The product name "Tuftec P1500" (hydrogenated styrene-based elastomer) manufactured by Asahi Kasei Corporation was used. The acid value of this copolymer is 0 mgKOH / g, the styrene / ethylene-butylene ratio is 30 / 70, and the weight average molecular weight is 67,000. (Styrene-based elastomer containing an amino group) The product name "Tuftec MP10" (amine-modified hydrogenated styrene-butadiene copolymer (amine-modified styrene-ethylene-butylene-styrene copolymer)) manufactured by Asahi Kasei Corporation was used. The styrene ratio of this copolymer is 30, and the weight average molecular weight is 78,000. (Epoxy resin) The product name "HP-7200" (epoxy resin, softening point 56-66 °C) manufactured by DIC Corporation was used. (Epoxy resin) The product name "Epofrend CT310" (epoxidized styrene-butadiene block copolymer) manufactured by Daicel Corporation was used. The styrene / ethylene-butylene ratio of this copolymer is 40 / 60, the weight average molecular weight is 93,000, and the epoxy equivalent is 2125 g / eq. (Solvent) A mixed solvent consisting of toluene and methyl ethyl ketone (mass ratio = 90:10) was used. (Base film) As the base film, "Shin-Etsu Sepla Film PEEK" (polyether ether ketone, thickness 50 μm) manufactured by Shin-Etsu Polymer Co., Ltd. was used. (Electrolytic copper foil) As the electrolytic copper foil, "TQ-M7-VSP" (electrolytic copper foil, thickness 12 μm, gloss surface Rz 1.27 μm, gloss surface Ra 0.197 μm, gloss surface Rsm 12.95 μm) manufactured by Mitsui Mining & Smelting Co., Ltd. was used. The surface roughness of the gloss surface was measured using a laser microscope to obtain a roughness curve, and the values were determined based on JIS B 0601:2013 (ISO 4287:1997 Amd.1:2009) from this roughness curve. (Release film) As the release film, NP75SA (silicone release PET film, 75 μm) manufactured by Panac Co., Ltd. was used. (Filler) As the filler, the fillers described below were used. MK-100DS micro mica (mica) (manufactured by Katakura Koppu Appri Co., Ltd.) Aspect ratio 27.5 UHP-S2 hexagonal boron nitride (manufactured by Showa Denko K.K.) Aspect ratio 6 MX-300 acrylic particles (manufactured by Soken Chemical & Engineering Co., Ltd.) SQ-C8 silica (manufactured by Admatechs Co., Ltd.) MC6000 melamine isocyanurate (manufactured by Nissan Chemical Industries, Ltd.)

[0071] (Example 1) Each component constituting the resin composition shown in Table 1 was contained in the ratio shown in Table 1 to prepare a resin composition. Next, each component constituting the adhesive layer shown in Table 2 was contained in the ratio shown in Table 2, and these components were dissolved in a solvent to prepare a resin varnish having a solid content concentration of 20% by mass. The shape and average particle diameter of the filler used are shown in Table 2. The surface of the base film was subjected to corona treatment. The resin varnish was applied to the surface of the base film and dried in an oven at 110 °C for 4 minutes to volatilize toluene, thereby forming an adhesive layer, and a base film with an adhesive was obtained. The adhesive layer of the adhesive laminate was overlapped so as to contact the glossy surface of the electrolytic copper foil, and thermal lamination was performed at 120 °C to obtain a pre-cured adhesive laminate. The pre-cured adhesive laminate was pressed at 180 °C, 3 MPa for 3 minutes, and then post-cured at 180 °C for 30 minutes to cure the adhesive layer and obtain a post-cured adhesive laminate. The adhesion force (N / cm) between the electrolytic copper foil and the base film of the post-cured adhesive laminate of Example 1 was measured.

[0072] [Adhesion force (N / cm)] The adhesion force was measured by cutting the post-cured adhesive laminate into a test piece with a width of 25 mm, and measuring the peel strength when peeling the electrolytic copper foil from the base film with an adhesive fixed to the support at a peel rate of 0.3 m / min and a peel angle of 180° in accordance with JIS Z0237:2009 (Test method for adhesive tapes and adhesive sheets).

[0073] Furthermore, the storage elastic modulus (Pa) at 25 °C after curing and 150 °C before curing was also measured.

[0074] [Storage elastic modulus (Pa)] The storage elastic modulus of the adhesive layer was measured for a sample composed of the adhesive layer. An adhesive film with a thickness of 100 μm was prepared. Using a viscoelasticity measuring device (RSA-G2 manufactured by TA Instruments), in accordance with JIS K7244 under the conditions of a measurement frequency of 1 Hz and a heating rate of 5 °C / min, the measurement was carried out. The measurement sample was prepared by roll-coating a resin varnish on a release film, and then the film with the coating was left standing in an oven and dried at 110 °C for 4 minutes to form a B-stage adhesive layer (thickness 50 μm). Next, this adhesive layer was thermally laminated at 120 °C so that the adhesive surfaces were in contact with each other to form a pre-cured adhesive film (thickness 100 μm), and a pre-cured adhesive film (100 mm × 100 mm) was prepared. The release film was peeled off from the adhesive film, and the storage elastic modulus (Pa) of the pre-cured adhesive layer was measured. Also, the pre-cured adhesive film (thickness 100 μm) was left standing in an oven and heat-cured at 150 °C for 60 minutes to prepare a post-cured adhesive film (100 mm × 100 mm). The release film was peeled off from the adhesive film, and the storage elastic modulus (Pa) of the post-cured adhesive layer was measured.

[0075] Regarding the adhesive layer in the post-cured adhesive laminate of Example 1, the relative permittivity and dielectric tangent at a frequency of 28 GHz were also measured.

[0076] [Relative permittivity and dielectric tangent] The relative permittivity and dielectric loss tangent of the adhesive layer were measured under the conditions of a temperature of 23°C and a frequency of 28 GHz by the open resonator method using a network analyzer MS46122B (manufactured by Anritsu Corporation) and an open resonator Fabry-Perot DPS-03 (manufactured by KEYCOM Corporation). The measurement sample was prepared by roll-coating a resin varnish on a release film, and then leaving the film with the coating in an oven and drying it at 110°C for 4 minutes to form a B-stage adhesive layer (thickness: 50 μm). Next, the adhesive layers were thermally laminated at 120°C so that the adhesive surfaces were in contact with each other to form a pre-cured adhesive film (thickness: 100 μm). The pre-cured adhesive film (thickness: 100 μm) was left in an oven and heat-cured at 150°C for 60 minutes to produce a post-cured adhesive film (100 mm × 100 mm). The release film was peeled off from the post-cured adhesive film, and the relative permittivity and dielectric loss tangent of the adhesive layer were measured.

[0077] For the adhesive layer in the post-cured adhesive laminate of Example 1, the coefficient of thermal expansion (CTE) at 30 to 50°C was also measured.

[0078] [Coefficient of Thermal Expansion (CTE)] The measurement of the coefficient of thermal expansion was carried out by the tensile mode using a thermomechanical analyzer [product name: SII / / SS7100, manufactured by Hitachi High-Technologies Corporation], with a load of 50 mN and a heating rate of 5°C / min. The temperature was raised from 25°C to 125°C at a rate of 5°C / min, the temperature change of the dimensions was measured, and the coefficient of linear expansion was obtained from the slope in the range from 30°C to 50°C.

[0079] A solder heat resistance test was conducted on the post-cured adhesive laminate of Example 1.

[0080] [Solder Heat Resistance Test] In the solder heat resistance test, with the substrate film surface facing up, the post-cured adhesive laminate was floated in a solder bath at 288°C for 10 seconds × 3 times, and it was confirmed whether there were any appearance abnormalities such as swelling 、 or peeling of the adhesive layer. The heat resistance of the laminate was evaluated according to the following evaluation criteria. ◎ No abnormality (no dissolution). ○ There is no abnormality finally, but softening of the adhesive layer is observed during the test. △ There is no peeling, but the adhesive layer has softened and a "stain pattern" has formed. × Peeling has occurred.

[0081] For the laminate of Example 1, a resin flow test of the adhesive layer was conducted during the production of the laminate.

[0082] [Resin Flow Test] In the resin flow test, the base film with adhesive was cut into a size of 30 mm × 90 mm, and three 5-mm-diameter holes were made using a belt punch. The base film with adhesive was overlapped so that the adhesive layer was in contact with the shiny surface of the electrolytic copper foil, and thermal lamination was performed at 150°C, followed by pressing at 180°C, 3 MPa, for 3 minutes. The length of the resin protruding from the copper foil was measured at 12 points (4 points × 3 locations) using a microscope [Product name: DIGITAL MICROSCOPE VHX-500, manufactured by KEYENCE, lens magnification: 300 times], and the average value was recorded.

[0083] Each measurement result is shown in Table 3.

[0084] (Examples 2 to 11) In Example 1, except that the types and blending amounts of the components constituting the adhesive layer were changed as shown in Tables 1 and 2, laminates of Examples 2 to 11 were produced in the same manner as in Example 1. The produced laminates were evaluated in the same manner as in Example 1. The results are shown in Table 3.

[0085] (Comparative Examples 1 to 8) In Example 1, except that the types and blending amounts of the components constituting the adhesive layer were changed as shown in Tables 1 and 2, laminates of Comparative Examples 1 to 8 were produced in the same manner as in Example 1. The produced laminates were evaluated in the same manner as in Example 1. The results are shown in Table 3.

[0086]

Table 1

[0087]

Table 2

[0088]

Table 3

Industrial Applicability

[0089] The laminate having an adhesive layer composed of the adhesive composition of the present invention can be suitably used for the production of FPC-related products for electronic devices such as smartphones, mobile phones, optical modules, digital cameras, game machines, notebook computers, and medical devices.

Claims

1. An adhesive composition containing a resin composition containing at least a styrene-based elastomer containing an amino group and an inorganic filler, wherein the content of the inorganic filler is 1 to 180 parts by mass with respect to 100 parts by mass of the resin composition, the inorganic filler has a plate-like or flaky shape, and the adhesive composition obtained by curing the adhesive composition has a relative permittivity of 3.5 or less at a frequency of 28 GHz and a dielectric loss tangent of 0.005 or less at a frequency of 28 GHz.

2. The adhesive composition according to claim 1, wherein the aspect ratio of the inorganic filler is 5 to 500 or less.

3. The adhesive composition according to claim 1 or 2, wherein the average particle diameter of the inorganic filler is 3.0 μm or less.

4. The adhesive composition according to any one of claims 1 to 3, wherein the inorganic filler contains at least one of a silicon-based inorganic filler and boron nitride.

5. The adhesive composition according to claim 4, wherein the silicon-based inorganic filler contains at least one of mica and talc.

6. The adhesive composition according to any one of claims 1 to 5, wherein the resin composition contains an epoxy resin.

7. The adhesive composition according to claim 6, wherein the content of the epoxy resin is 1 to 25 parts by mass with respect to 100 parts by mass of the resin composition.

8. The adhesive composition according to any one of claims 1 to 7, wherein the storage elastic modulus of the uncured adhesive layer of the adhesive composition at 150 °C is 1.0E+5 Pa or more.

9. A laminate having a base film and an adhesive layer made of an adhesive composition, wherein the adhesive composition is an adhesive composition containing a resin composition containing at least a styrene-based elastomer and an inorganic filler, the content of the inorganic filler is 1 to 180 parts by mass with respect to 100 parts by mass of the resin composition, the inorganic filler has a plate-like or flaky shape, and the adhesive composition obtained by curing the adhesive composition has a relative permittivity of 3.5 or less at a frequency of 28 GHz and a dielectric loss tangent of 0.005 or less at a frequency of 28 GHz, and the base film contains a polyether ether ketone (PEEK) resin.

10. A printed wiring board including the laminate according to claim 9.

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