KR102189258B1 - Low dielectric adhesive composition - Google Patents

Abstract

The present invention has high adhesion to conventional polyimide and polyester films, as well as low-polarity resin or metal substrates such as LCP, high solder heat resistance, and excellent low dielectric properties and pot life properties. Provides.
An adhesive composition containing a solvent-soluble resin and satisfying the following (1) to (4). (1) The cured product of the adhesive composition has a relative dielectric constant (ε _c ) of 3.0 or less at a frequency of 1 MHz. (2) The cured product of the adhesive composition has a dielectric loss tangent (tan?) of 0.02 or less at a frequency of 1 MHz. (3) The 90° peeling strength of the laminate obtained by bonding the liquid crystal polymer film and copper foil with the adhesive composition was 0.5 N/mm or more. (4) The solution viscosity ratio (solution viscosity (ηB)/solution viscosity (ηB0)) of the toluene solution (solid content concentration 20% by mass) of the solvent-soluble resin is 0.5 or more and less than 3.0. Solution viscosity (ηB0) is the viscosity of the solution at 25°C immediately after dissolving the solvent-soluble resin in toluene, and the solution viscosity (ηB) is at 25°C after dissolving the solvent-soluble resin in toluene and storing for 7 days at 5°C. Is the viscosity of the solution.

Description

Low dielectric adhesive composition

The present invention relates to an adhesive composition exhibiting a low dielectric constant and low dielectric loss tangent. In more detail, it relates to an adhesive composition used for bonding a resin substrate and a resin substrate or a metal substrate. In particular, it relates to an adhesive composition for a flexible printed wiring board (hereinafter referred to as FPC), and a coverlay film containing the same, a laminate, a copper foil having a resin, and a bonding sheet.

BACKGROUND ART [0002] In recent years, with the high speed of transmission signals in printed wiring boards, the high frequency of signals is in progress. Accordingly, the demand for low dielectric properties (low dielectric constant, low dielectric loss tangent) in a high frequency region is increasing in FPC. In response to these needs, as a base film used for FPC, instead of the conventional polyimide (PI) and polyethylene terephthalate films, liquid crystal polymers (LCP) having low dielectric properties, syndiotactic polystyrene (SPS), and polyphenylenesulfide Base films such as feed (PPS) have been proposed.

However, since a base film having a low dielectric property has low polarity, when a conventional epoxy adhesive or acrylic adhesive is used, the adhesive strength is weak, making it difficult to manufacture FPC members such as a coverlay film and a laminate. In addition, epoxy-based adhesives or acrylic-based adhesives do not have excellent low-dielectric properties, thus impairing the dielectric properties of FPC.

On the other hand, it is known that polyolefin resins have low dielectric properties. Thus, an adhesive composition for FPC using a polyolefin resin has been proposed. For example, in Patent Document 1, a polyolefin-based copolymer containing a carboxyl group, a block copolymer of an aromatic vinyl compound polymer block and a conjugated diene-based compound polymer block, and a thermally reactive adhesive composition using an epoxy resin are proposed. In addition, in Patent Document 2, an adhesive composition using a carboxyl group-containing styrene elastomer and an epoxy resin is proposed.

Patent Document 1: Japanese Patent No. 33621351 Patent document 2: WO2014/147903A1 publication

However, in Patent Document 1, although the adhesiveness and solder heat resistance of the polyimide film and SUS are described, the dielectric properties are not mentioned, and it is difficult to obtain adhesiveness with a base film having low dielectric properties such as LCP. In addition, in Patent Document 2, although the dielectric properties and the adhesiveness of the polyimide film and the copper foil are described, the adhesiveness to the base film having low dielectric properties such as LCP is not mentioned.

In order to increase the adhesiveness of the low-polarity base film such as LCP as described above, it is necessary to increase the polarity of the adhesive composition or increase the cohesive force. However, in general, increasing the polarity lowers the dielectric properties of the adhesive itself. In addition, when a crystalline resin is used in order to increase the cohesive strength, the solvent solubility decreases and the pot life property deteriorates. Here, the pot life property refers to the stability of the main varnish immediately after dissolving the main resin in a solvent (main varnish) or after a certain period of time in a two-component adhesive agent comprising a main resin and a crosslinking agent or a curing agent.

In general, since polyolefins are crystalline, pot life properties in toluene or methyl ethyl ketone solvents, which are general-purpose solvents, are poor, and it is known that they solidify into purine-type under low temperature. Therefore, it is generally dissolved in an aliphatic hydrocarbon, an alicyclic hydrocarbon, or a halogenated hydrocarbon, but there are limitations such as working environment and drying conditions.

In order to solve the above problems, according to the present invention, the adhesive composition having specific physical properties is not only a conventional polyimide film, but also a resin substrate having low dielectric properties such as LCP, which is not assumed in the prior art, and copper foil. The present invention has been completed by discovering that it is excellent in high adhesion and low dielectric properties, and pot life properties at low temperatures with such metal substrates.

That is, it is an object of the present invention to provide an adhesive composition having good adhesion to both various resin substrates such as polyimide and LCP and metal substrates, and excellent in low dielectric properties and pot life properties.

An adhesive composition containing a solvent-soluble resin and satisfying the following (1) to (4).

(1) The cured product of the adhesive composition has a relative dielectric constant (ε _c ) of 3.0 or less at a frequency of 1 MHz.

(2) The dielectric loss tangent (tanδ) at a frequency of 1 MHz of the cured product of the adhesive composition is 0.02 or less.

(3) The 90° peeling strength of the laminate obtained by bonding the liquid crystal polymer film and copper foil with the adhesive composition is 0.5 N/mm or more.

(4) The solution viscosity ratio (solution viscosity (ηB)/solution viscosity (ηB0)) of the toluene solution (solid content concentration 20% by mass) of the solvent-soluble resin is 0.5 or more and less than 3.0

Solution viscosity (ηB0): Solution viscosity at 25°C immediately after dissolving the solvent-soluble resin in toluene

Solution viscosity (ηB): Solution viscosity at 25°C after dissolving a solvent-soluble resin in toluene and standing still at 5°C for 7 days

An adhesive sheet or laminate containing the adhesive composition.

A printed wiring board comprising the laminate as a component.

The adhesive composition according to the present invention contains a solvent-soluble resin, (1) the relative dielectric constant (ε _c ) of the cured product of the adhesive composition at a frequency of 1 MHz is 3.0 or less, and (2) the cured product of the adhesive composition has a frequency of 1 MHz. Dielectric loss tangent (tanδ) of 0.02 or less, (3) 90° peeling strength of a laminate obtained by bonding a liquid crystal polymer (LCP) film and copper foil with an adhesive composition of 0.5 N/mm or more, and (4) solvent-soluble resin Solution viscosity ratio [(solvent-soluble resin dissolved in toluene and stored still at 5°C for 7 days, then solution viscosity (ηB) at 25°C)/(solvent-soluble resin toluene Since the solution viscosity (ηB0)) at 25°C immediately after dissolving in] satisfies that it is 0.5 or more and less than 3.0, it is not only conventional polyimide and polyester films, but also low-polarity resins such as LCP films, which are not assumed in the prior art. It has high adhesion to a substrate or a metal substrate, and has excellent low dielectric properties and pot life properties.

Hereinafter, embodiments of the present invention will be described in detail. The adhesive composition according to the present invention contains a solvent-soluble resin and satisfies the following requirements (1) to (4).

<Solvent-soluble resin>

The solvent-soluble resin used in the present invention is not particularly limited as long as it is a resin dissolved in toluene at a concentration of 20% by mass or more at 25°C, but is preferably an acid-modified polystyrene elastomer resin described later. Further, it is preferably dissolved in toluene at a concentration of 25% by mass or more at 25°C, and more preferably 30% by mass or more.

<Requirement (1)>

The requirement (1) will be described. The adhesive composition according to the present invention is required to have a relative dielectric constant (ε _c ) of 3.0 or less at a frequency of 1 MHz of the cured product of the adhesive composition. Specifically, the adhesive composition is applied to a release substrate so that the thickness after drying becomes 25 µm, and dried at about 130°C for about 3 minutes. Subsequently, it is cured by heat treatment at about 140°C for about 4 hours, and the cured adhesive composition layer (hereinafter, also referred to as an adhesive layer) is peeled from the release film. The relative dielectric constant (ε _c ) of the adhesive composition layer after peeling at a frequency of 1 MHz is measured. For measurement, a metal layer is formed on both sides of the adhesive layer by a thin film method such as vapor deposition or sputtering, or a conductive paste is applied to form a capacitor, and the capacitance is measured to determine the relative dielectric constant (ε _c ) from the thickness and area. How to calculate can be illustrated.

Further, from the laminate (resin substrate/adhesive layer/metal substrate), the metal substrate of the laminate is removed cleanly with an etching solution, and a laminate of two layers of an adhesive layer and a resin substrate is obtained. The etching solution is not particularly limited, and a ferric chloride aqueous solution, a cupric chloride aqueous solution, a mixed solution of a sulfuric acid hydrogen peroxide solution, an alkali etching agent, a nickel etching agent, or the like can be used. Subsequently, the resin substrate of the two-layer laminate (adhesive layer/resin substrate) is removed (removed) cleanly, and a thin film method such as vapor deposition, sputtering method, or conductive paste is applied on both sides of the remaining adhesive layer. Thus, a method of forming a metal layer to form a capacitor, measuring the electrostatic capacity, and calculating the relative dielectric constant (ε _c ) from the thickness and area can be illustrated. In addition, as another method, a metal layer is formed on the resin substrate surface of a two-layer laminate (adhesive layer/resin substrate) by the method described above to form a capacitor, and the composite capacitance relative dielectric constant (ε _c ) of the resin substrate and the adhesive layer After measuring, the metal layer and the adhesive layer are cleanly peeled off (removed) from the two-layer laminate, and the relative dielectric constant (ε _c ) of the remaining resin substrate is similarly converted into a capacitor, and the capacitance is measured. Since the dielectric layer of a capacitor obtained from a two-layer laminate (adhesive layer/resin substrate) can be regarded as a multilayer dielectric of a resin substrate and an adhesive layer, the relative dielectric constant (ε _c ) of the adhesive layer can be calculated from the difference between the two. have.

The relative dielectric constant (ε _c ) is 3.0 or less, preferably 2.6 or less, and more preferably 2.3 or less. Although the lower limit is not particularly limited, it is practically 2.0. Moreover, it is preferable that the relative dielectric constant (ε _c ) in the whole range of the frequency of 1 MHz to 10 GHz is 3.0 or less, more preferably 2.6 or less, and still more preferably 2.3 or less.

<Requirement (2)>

The requirement (2) will be described. The adhesive composition according to the present invention is required to have a dielectric loss tangent (tanδ) of 0.02 or less at a frequency of 1 MHz of the cured product of the adhesive composition. Specifically, the adhesive composition is applied to a release substrate so that the thickness after drying becomes 25 µm, and dried at about 130°C for about 3 minutes. Subsequently, it is cured by heat treatment at about 140° C. for about 4 hours, and the cured adhesive composition layer is peeled from the release film. The dielectric loss tangent (tanδ) at a frequency of 1 MHz of the adhesive composition after peeling was measured. The dielectric loss tangent (tanδ) is 0.02 or less, preferably 0.01 or less, and more preferably 0.005 or less. Although the lower limit is not particularly limited, it is practically 0.0001. Moreover, it is preferable that the dielectric loss tangent (tanδ) in the whole region of the frequency 1 MHz to 10 GHz is 0.02 or less, more preferably 0.01 or less, and still more preferably 0.005 or less.

The dielectric loss tangent (tanδ) of the cured product of the adhesive composition can also be measured by the same operation as the relative dielectric constant.

<Requirement (3)>

The requirement (3) will be described. The adhesive composition according to the present invention is required to have a 90° peeling strength of 0.5 N/mm or more of a laminate obtained by bonding a liquid crystal polymer (LCP) film and copper foil with the adhesive composition. Specifically, the adhesive composition according to the present invention is applied to the LCP film so that the thickness after drying is about 25 μm, and dried at about 130° C. for about 3 minutes. Subsequently, copper foil is bonded to the surface of the adhesive composition layer. Bonding is performed by vacuum pressing for about 30 seconds under pressure of about 40 kgf/cm 2 at about 160°C with the glossy surface of the copper foil in contact with the adhesive composition layer. Subsequently, heat treatment was performed at about 140° C. for about 4 hours to cure, thereby producing a three-layer laminate of LCP film/adhesive composition layer/copper foil. At room temperature (about 25°C), the LCP film of the laminate is peeled at 90° at a tensile speed of 50 mm/min, and peel strength is measured. The 90° peeling strength is required to be 0.5 N/mm or more, preferably 0.8 N/mm or more, and more preferably 1.0 N/mm or more. Moreover, as a commercial item of an LCP film, Bexta (registered trademark) manufactured by Kuraray Co., Ltd. can be mentioned, for example.

<Requirement (4)>

The requirement (4) will be described. The adhesive composition according to the present invention needs to have a solution viscosity ratio (solution viscosity (ηB)/solution viscosity (ηB0)) of 0.5 or more and less than 3.0 when the solvent-soluble resin is dissolved in toluene so that the solid content concentration is 20% by mass. . Here, the solution viscosity (ηB0) is the viscosity of the solution at 25°C immediately after dissolving the solvent-soluble resin in toluene, and the solution viscosity (ηB) is 25 after dissolving the solvent-soluble resin in toluene and standing still at 5°C for 7 days. It is the viscosity of the solution in °C. A preferred solution viscosity ratio is 0.7 or more and 2.0 or less, and more preferably 0.8 or more and 1.5 or less. In addition, the solution viscosity (ηB0) and the solution viscosity (ηB) are preferably 100 dPa·s or less, and more preferably 75 dPa·s or less, respectively. If it exceeds 100 dPa·s, it may become difficult to coat evenly. In addition, the lower limit is not particularly limited, but it is preferably 1 dPa·s or more for practical purposes.

The adhesive composition according to the present invention is not particularly limited in order to satisfy the above (1) to (4), but it is preferable to contain the following components (A) to (C). By containing the components (A) to (C), excellent adhesion, low dielectric properties, and pot life properties can be obtained. Hereinafter, components (A) to (C) will be described.

<(A) component: acid-modified polystyrene elastomer resin>

The component (A) is preferably an acid-modified polystyrene elastomer resin (hereinafter, also referred to as an acid-modified polystyrene elastomer resin (A)). The acid-modified polystyrene elastomer resin (A) used in the present invention is not limited, but an aromatic vinyl compound alone or a copolymer mainly having a block and/or random structure of an aromatic vinyl compound and a conjugated diene compound, and a hydrogenated product thereof It is preferable that it is modified with an unsaturated carboxylic acid. Although it does not specifically limit as an aromatic vinyl compound, For example, styrene, t-butylstyrene, α-methylstyrene, p-methylstyrene, divinylbenzene, 1,1-diphenylstyrene, N,N-diethyl-p-amino Ethyl styrene, vinyl toluene, p-tertiary butyl styrene, etc. are mentioned. In addition, as a conjugated diene compound, butadiene, isoprene, 1,3-pentadiene, 2,3-dimethyl-1,3-butadiene, etc. are mentioned, for example. Specific examples of the copolymer of these aromatic vinyl compounds and conjugated diene compounds include styrene-ethylene-butylene-styrene block copolymer (SEBS), styrene-ethylene-propylene-styrene block copolymer (SEPS), and styrene-ethylene-ethylene. A propylene-styrene block copolymer (SEEPS), etc. are mentioned.

Modification with an unsaturated carboxylic acid (synthesis of an acid-modified polystyrene elastomer resin (A)) can be performed, for example, by copolymerizing an unsaturated carboxylic acid during polymerization of a styrene resin. Further, it can also be carried out by heating and kneading a styrene resin and an unsaturated carboxylic acid in the presence of an organic peroxide. It does not specifically limit as an unsaturated carboxylic acid, Acrylic acid, methacrylic acid, maleic acid, itaconic acid, fumaric acid, maleic anhydride, itaconic anhydride, fumaric anhydride, etc. are mentioned.

The acid value of the acid-modified polystyrene elastomer resin (A) is preferably 10 equivalents/10 ⁶ g or more, and more preferably 100 equivalents/10 ⁶ g or more, from the viewpoint of heat resistance and adhesion to a resin substrate or a metal substrate. , More preferably 150 equivalents/10 ⁶ g. If it is less than the above value, compatibility with the epoxy resin (C) and the carbodiimide resin (B) is low, and the adhesive strength may not be expressed. In addition, the crosslinking density is low, and heat resistance may be insufficient. The upper limit is preferably 1000 equivalents/10 ⁶ g or less, more preferably 700 equivalents/10 ⁶ g or less, and still more preferably 500 equivalents/10 ⁶ g or less. When the above value is exceeded, the adhesiveness and low dielectric properties may decrease.

The content of the component (A) in the adhesive composition of the present invention is preferably 10% by mass or more, more preferably 20% by mass or more, and still more preferably 40% by mass or more. Moreover, it is preferable that it is 99 mass% or less, 95 mass% or less is more preferable, and 90 mass% or less is still more preferable. Even if there is too much at least too much, adhesiveness and heat resistance may fall.

<(B) component: carbodiimide resin>

The component (B) is preferably a carbodiimide resin (hereinafter also referred to as carbodiimide resin (B)). The carbodiimide resin (B) is not particularly limited as long as it has a carbodiimide group in its molecule. It is preferably a polycarbodiimide having two or more carbodiimide groups in the molecule. By using the carbodiimide resin (B), the carboxyl group of the acid-modified polystyrene elastomer resin (A) reacts with the carbodiimide, thereby enhancing the interaction between the adhesive composition and the substrate, thereby improving adhesion.

In the adhesive composition of the present invention, the content of the carbodiimide resin (B) is preferably in the range of 0.1 to 30 parts by mass with respect to 100 parts by mass of the acid-modified polystyrene elastomer resin (A). It is more preferably in the range of 1 to 25 parts by mass, and most preferably in the range of 2 to 20 parts by mass. If it is less than the above value, there is a problem that the interaction with the substrate is not exhibited and the adhesiveness is lowered. If the above value is exceeded, there is a problem that the port life of the adhesive decreases and the low dielectric property decreases.

<(C) component: epoxy resin>

The component (C) is an epoxy resin (hereinafter, also referred to as an epoxy resin (C)). The epoxy resin (C) is not particularly limited as long as it has a glycidyl group in the molecule, but preferably has two or more glycidyl groups in the molecule. Specifically, although not particularly limited, biphenyl type epoxy resin, naphthalene type epoxy resin, bisphenol A type epoxy resin, bisphenol F type epoxy resin, novolac type epoxy resin, alicyclic epoxy resin, dicyclopentadiene type epoxy resin , Tetraglycidyldiaminodiphenylmethane, triglycidylparaaminophenol, tetraglycidylbisaminomethylcyclohexanone, N,N,N',N'-tetraglycidyl-m-xylenediamine At least one selected from the group may be used. Preferably, it is a biphenyl type epoxy resin, a novolac type epoxy resin, or a dicyclopentadiene type epoxy resin.

In the adhesive composition of the present invention, the content of the epoxy resin (C) is preferably in the range of 1 to 30 parts by mass, and in the range of 2 to 15 parts by mass with respect to 100 parts by mass of the acid-modified polystyrene elastomer resin (A). It is more preferable, and it is most preferable that it is the range of 3-10 mass parts. If it is less than the above range, a sufficient curing effect cannot be obtained, and adhesiveness and heat resistance may decrease. In addition, above the above range, there is a problem that the port life of the adhesive decreases and the low dielectric property decreases.

<Adhesive composition>

The adhesive composition of the present invention has (1) a dielectric constant (ε _c ) of 3.0 or less at a frequency of 1 MHz of the cured product of the adhesive composition, and (2) a dielectric loss tangent (tanδ) of 0.02 at a frequency of 1 MHz of the cured product of the adhesive composition The following, (3) 90° peeling strength of a laminate obtained by bonding a liquid crystal polymer (LCP) film and copper foil with an adhesive composition of 0.5 N/mm or more, and (4) a toluene solution of a solvent-soluble resin (solid content concentration of 20% by mass) ) Of the solution viscosity ratio [(solution viscosity (ηB) at 25°C after dissolving the solvent-soluble resin in toluene and standing still at 5°C for 7 days)/(at 25°C immediately after dissolving the solvent-soluble resin in toluene Solution viscosity (ηB0))] satisfies 0.5 or more and less than 3.0. Although it does not specifically limit in order to satisfy said (1)-(4), It is preferable that it is a composition containing the said acid-modified polystyrene elastomer resin (A), carbodiimide resin (B), and epoxy resin (C).

The adhesive composition of the present invention contains three types of resins (A) to (C), and thus excellent adhesion to low polarity resin substrates such as LCP or metal substrates, pot life properties, and electrical properties (low dielectric Trait) can be expressed. That is, the adhesive coating film (adhesive layer) after applying and curing the adhesive composition to a substrate can exhibit excellent low dielectric constant characteristics.

The adhesive composition of the present invention may further contain an organic solvent. The organic solvent used in the present invention is not particularly limited as long as it dissolves the acid-modified polystyrene elastomer resin (A), carbodiimide resin (B), and epoxy resin (C). Specifically, for example, aromatic hydrocarbons such as benzene, toluene, and xylene, aliphatic hydrocarbons such as hexane, heptane, octane, and decane, alicyclic hydrocarbons such as cyclohexane, cyclohexene, methylcyclohexane, and ethylcyclohexane, and trichloro Halogenated hydrocarbons such as ethylene, dichloroethylene, chlorobenzene, and chloroform, alcohol-based solvents such as methanol, ethanol, isopropyl alcohol, butanol, pentanol, hexanol, propanediol, phenol, acetone, methyl isobutyl ketone, methyl ethyl Ketone solvents such as ketone, pentanone, hexanone, cyclohexanone, isophorone, and acetophenone, cellosolves such as methyl cellosolve and ethyl cellosolve, methyl acetate, ethyl acetate, butyl acetate, methyl propionate, Ester solvents such as butyl formate, ethylene glycol mono-n-butyl ether, ethylene glycol mono-iso-butyl ether, ethylene glycol mono-tert-butyl ether, diethylene glycol mono-n-butyl ether, diethylene glycol mono- Glycol ether solvents, such as iso-butyl ether, triethylene glycol mono-n-butyl ether, and tetraethylene glycol mono-n-butyl ether, etc. can be used, and these 1 type or 2 or more types can be used together. Particularly, toluene is preferred from the viewpoint of working environment and drying properties.

The organic solvent is preferably in the range of 100 to 1000 parts by mass, more preferably in the range of 200 to 900 parts by mass, and most preferably in the range of 300 to 800 parts by mass based on 100 parts by mass of the acid-modified polystyrene elastomer resin (A). Do. If it is less than the above range, the liquid form and pot life properties may decrease. In addition, when it exceeds the above range, there is a problem that the manufacturing cost and transportation cost become disadvantageous.

Further, the adhesive composition of the present invention may further contain other components as necessary. As a specific example of such a component, a flame retardant, a tackifier, a filler, and a silane coupling agent are mentioned.

It is preferable to reduce the content of the crystalline resin in the adhesive composition of the present invention in order to express good pot life. Crystallinity refers to the fact that the temperature is increased from -100°C to 250°C at 20°C/min using a differential scanning calorimeter (DSC), and a clear melting peak is exhibited during the heating process. Examples of the crystalline resin include polyolefin resins such as polyethylene, polypropylene, and polybutene, and acid-modified polyolefin resins. The content of these crystalline resins is preferably 20 parts by mass or less, more preferably 10 parts by mass or less, further preferably 5 parts by mass or less, particularly preferably 1 part by mass or less, based on 100 parts by mass of the solvent-soluble resin. , It is okay to add 0 mass. If it is too large, the port life property may decrease.

<Flame retardant>

If necessary, a flame retardant may be added to the adhesive composition of the present invention. Examples of the flame retardant include bromine, phosphorus, nitrogen, and metal hydroxide compounds. Among them, phosphorus-based flame retardants are preferred, and known phosphorus-based flame retardants such as phosphate esters such as trimethyl phosphate, triphenyl phosphate, tricresyl phosphate, etc., phosphates such as aluminum phosphinate, and phosphazene can be used. These may be used singly or two or more may be used in combination. When containing a flame retardant, it is preferable to contain a flame retardant in the range of 1 to 200 parts by mass, more preferably 5 to 150 parts by mass, and more preferably 10 to 100 parts by mass of the total of components (A) to (C). The range of 100 parts by mass is most preferred. If it is less than the above range, the flame retardancy may be low. If it exceeds the above range, there is a problem that adhesiveness, heat resistance, electrical properties, etc. deteriorate.

<Adhesive imparting agent>

If necessary, a tackifier may be blended into the adhesive composition of the present invention. Examples of the tackifying agent include polyterpene resins, rosin resins, aliphatic petroleum resins, alicyclic petroleum resins, copolymerized petroleum resins, styrene resins and hydrogenated petroleum resins, and are used for the purpose of improving adhesive strength. These may be used singly or two or more may be used in combination.

<filler>

In the adhesive composition of the present invention, if necessary, a filler such as silica may be blended. It is very preferable because the heat resistance property is improved by blending silica. As silica, hydrophobic silica and hydrophilic silica are generally known, but hydrophobic silica treated with dimethyldichlorosilane, hexamethyldisilazane, octylsilane, or the like is preferable to impart moisture resistance. The blending amount of silica is preferably 0.05 to 30 parts by mass with respect to 100 parts by mass in total of components (A) to (C). If it is less than 0.05 parts by mass, the effect of improving heat resistance may not be exhibited. On the other hand, when it exceeds 30 parts by mass, poor dispersion of silica may occur or the viscosity of the solution may increase, resulting in a problem in workability or poor adhesion.

<Silane coupling agent>

If necessary, a silane coupling agent may be blended in the adhesive composition of the present invention. By blending a silane coupling agent, it is very preferable because the properties of adhesion to metal and heat resistance are improved. Although it does not specifically limit as a silane coupling agent, What has an unsaturated group, what has a glycidyl group, what has an amino group, etc. are mentioned. Among these, from the viewpoint of heat resistance, γ-glycidoxypropyltrimethoxysilane, β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane or β-(3,4-epoxycyclohexyl)ethyltriethoxysilane A silane coupling agent having a glycidyl group such as a glycidyl group is more preferable. The blending amount of the silane coupling agent is preferably 0.5 to 20 parts by mass based on 100 parts by mass in total of the components (A) to (C). If it is less than 0.5 parts by mass, heat resistance may be poor. On the other hand, when it exceeds 20 parts by mass, poor heat resistance and adhesiveness may decrease.

<Laminate>

The laminate of the present invention is a laminate of an adhesive composition on a substrate (a two-layer laminate of a substrate/adhesive layer), or a laminate of a substrate further (a three-layer laminate of a substrate/adhesive layer/substrate). Here, the adhesive layer refers to a layer of the adhesive composition after the adhesive composition of the present invention is applied to a substrate and dried. The laminate of the present invention can be obtained by applying and drying the adhesive composition of the present invention to various substrates and further laminating other substrates according to a conventional method.

It is preferable that the laminate of the present invention has a dry solder heat resistance of 290°C or higher. Specifically, the adhesive composition is applied to a resin substrate so that the thickness after drying becomes 25 µm, and dried at about 130°C for about 3 minutes. Subsequently, a metal substrate is bonded to the surface of the adhesive composition layer (adhesive layer). Bonding is performed by vacuum pressing for about 30 seconds under a pressure of about 40 kgf/cm 2 at about 160°C with the glossy surface of the metal substrate in contact with the adhesive composition layer. Subsequently, it is cured by heat treatment at about 140° C. for about 4 hours to prepare a three-layer laminate of a resin substrate/adhesive layer/metal substrate. The three-layer laminate was dried at about 120° C. for about 30 minutes, and flowed for 1 minute in a molten solder bath at each temperature to measure a temperature at which no change in appearance such as expansion occurs. The dry solder heat resistance is preferably 290°C or higher, more preferably 300°C or higher, and still more preferably 310°C or higher. It is preferable that it is a polyimide film or an LCP film as a resin base material, copper foil is preferable as a metal base material, It is preferable that the said dry solder heat resistance is satisfied with a laminate using these base materials.

<material>

In the present invention, the substrate is not particularly limited as long as it can form an adhesive layer by applying and drying the adhesive composition of the present invention, but a resin substrate such as a film-type resin, a metal substrate such as a metal plate or a metal foil, paper, etc. Can be lifted.

Examples of the resin substrate include polyester resin, polyamide resin, polyimide resin, polyamideimide resin, liquid crystal polymer, polyphenylene sulfide, syndiotactic polystyrene, polyolefin resin and fluorine resin. It is preferably a film-type resin (hereinafter, also referred to as a base film layer).

As the metal substrate, any conventionally known conductive material usable for circuit boards can be used. Examples of the material include various metals such as SUS, copper, aluminum, iron, steel, zinc, and nickel, and alloys, plated products, and metals treated with other metals such as zinc or chromium compounds. Preferably, it is a metal foil, More preferably, it is a copper foil. The thickness of the metal foil is not particularly limited, but is preferably 1 µm or more, more preferably 3 µm or more, and still more preferably 10 µm or more. Further, it is preferably 50 µm or less, more preferably 30 µm or less, and still more preferably 20 µm or less. When the thickness is too thin, it may be difficult for the circuit to obtain sufficient electrical performance. On the other hand, when the thickness is too thick, the processing efficiency and the like at the time of circuit production may decrease. The metal foil is usually provided in the form of a roll. The form of the metal foil used when manufacturing the printed wiring board of this invention is not specifically limited. In the case of using a ribbon-shaped metal foil, the length is not particularly limited. Further, the width is also not particularly limited, but is preferably about 250 to 500 cm.

Examples of papers include high-quality paper, kraft paper, roll paper, glassine paper, and the like. Moreover, glass epoxy etc. can be illustrated as a composite material.

From the adhesive strength and durability of the adhesive composition, the base material is polyester resin, polyamide resin, polyimide resin, polyamideimide resin, liquid crystal polymer, polyphenylene sulfide, syndiotactic polystyrene, polyolefin resin, fluorine resin, SUS Steel plate, copper foil, aluminum foil, or glass epoxy is preferable.

<Adhesive sheet>

In the present invention, the adhesive sheet is a laminated body and a release base material through an adhesive composition, or a release base material and a release base material are laminated through an adhesive composition, or a release base material on at least one side of the adhesive layer Is stacked. As a specific configuration aspect, a release base material / adhesive layer, a laminate / adhesive layer / release base material, a release base material / adhesive layer / release base material, or a release base material / adhesive layer / laminate / adhesive layer / release base material may be mentioned. By laminating a release substrate, it functions as a protective layer of the substrate. In addition, by using the release base material, the release base material can be released from the adhesive sheet, and the adhesive layer can be transferred to another base material.

By applying and drying the adhesive composition of the present invention to various laminates according to a conventional method, the adhesive sheet of the present invention can be obtained. In addition, if a release base material is attached to the adhesive layer after drying, it is possible to wind up without causing contamination to the base material, so that it has excellent operability, and since the adhesive layer is protected, it is excellent in storage and easy to use. In addition, by applying and drying the release base material to a separate release base material as necessary, the adhesive layer itself can be transferred to another base material.

<release material>

Although it does not specifically limit as a release base material, For example, on both sides of paper such as high-quality paper, kraft paper, roll paper, glassine paper, a coating layer of an eye plugging agent such as clay, polyethylene, polypropylene, etc. is provided, and each application thereof A silicone-based, fluorine-based, or alkyd-based release agent is further coated on the layer. In addition, various olefin films such as polyethylene, polypropylene, ethylene-α-olefin copolymer, and propylene-α-olefin copolymer, and those obtained by coating the above-described release agent on films such as polyethylene terephthalate may be mentioned. For reasons such as the release power of the release base material and the adhesive layer, and the silicone imparts adverse effects on the electrical properties, polypropylene eye plugs are treated on both sides of the high-quality paper, and an alkyd-based release agent is used thereon, or alkyd on polyethylene terephthalate. It is preferable to use a type release agent.

In addition, although it does not specifically limit as a method of coating an adhesive composition on a base material in this invention, A comma coater, a reverse roll coater, etc. are mentioned. Alternatively, if necessary, an adhesive layer may be provided directly or by a transfer method on a rolled copper foil or a polyimide film as a material for constituting a printed wiring board. The thickness of the adhesive layer after drying is appropriately changed as necessary, but is preferably in the range of 5 to 200 µm. If the adhesive film thickness is less than 5 µm, the adhesive strength is insufficient. In the case of 200 µm or more, drying is insufficient, and residual solvent is increased, and there is a problem that air bubbles are generated at the time of pressing for manufacturing a printed wiring board. Although drying conditions are not particularly limited, the residual solvent ratio after drying is preferably 1% by mass or less. When it exceeds 1 mass %, there is a problem that the residual solvent foams at the time of pressing the printed wiring board to generate air bubbles.

<Printed wiring board>

The "printed wiring board" in the present invention includes, as a constituent element, a laminate formed of a metal foil and a resin substrate forming a conductor circuit. The printed wiring board is manufactured according to a conventionally known method such as a subtractive method using a metal-clad laminate, for example. If necessary, a so-called flexible circuit board (FPC), a flat cable, a circuit board for tape automation bonding (TAB), etc., in which the conductor circuit formed by metal foil is partially or entirely covered with a cover film or screen printing ink, etc. It is collectively called.

The printed wiring board of the present invention can have any lamination structure that can be employed as a printed wiring board. For example, it can be set as a printed wiring board comprised of four layers of a base film layer, a metal foil layer, an adhesive layer, and a cover film layer. Further, for example, a printed wiring board composed of five layers of a base film layer, an adhesive layer, a metal foil layer, an adhesive layer, and a cover film layer can be obtained.

Further, if necessary, two or three or more printed wiring boards may be laminated.

The adhesive composition of the present invention can be suitably used for each adhesive layer of a printed wiring board. In particular, when the adhesive composition of the present invention is used as an adhesive, it has high adhesiveness with low polarity resin substrates such as LCP, as well as conventional polyimide, polyester film, and copper foil constituting a printed wiring board, and solder reflow resistance. Can be obtained, and the adhesive layer itself is excellent in low dielectric properties. Therefore, it is suitable as an adhesive composition used for a coverlay film, a laminated plate, a copper foil with resin, and a bonding sheet.

In the printed wiring board of the present invention, as the base film, any resin film conventionally used as the base material of the printed wiring board can be used. Examples of the resin of the base film include polyester resin, polyamide resin, polyimide resin, polyamideimide resin, liquid crystal polymer, polyphenylene sulfide, syndiotactic polystyrene, polyolefin resin and fluorine resin. In particular, it has excellent adhesion to a low polarity substrate such as a liquid crystal polymer, polyphenylene sulfide, syndiotactic polystyrene, and polyolefin resin.

<cover film>

As the cover film, any conventionally known insulating film can be used as an insulating film for a printed wiring board. For example, polyimide, polyester, polyphenylene sulfide, polyether sulfone, polyetheretherketone, aramid, polycarbonate, polyarylate, polyimide, polyamideimide, liquid crystal polymer, polyphenylene sulfide, syndiotactic polystyrene , It is possible to use a film made of various polymers such as polyolefin resin. More preferably, it is a polyimide film or a liquid crystal polymer film.

The printed wiring board of the present invention can be manufactured using any conventionally known process other than using the material of each layer described above.

In a preferred embodiment, a semi-finished product in which an adhesive layer is laminated on a cover film layer (hereinafter referred to as "cover film side semi-finished product") is produced. On the other hand, a semi-finished product in which a desired circuit pattern is formed by laminating a metal foil layer on the base film layer (hereinafter referred to as ``substrate film side two-layer semi-finished product'') or an adhesive layer is laminated on the base film layer, and a metal foil layer is laminated thereon. Manufacture a semi-finished product with a desired circuit pattern (hereinafter referred to as ``substrate film side 3 layer semi-finished product'') (hereinafter, the base film side 2 layer semi-finished product and the base film side 3 layer semi-finished product are combined to be referred to as ``substrate film side semi-finished product'' ). A four- or five-layer printed wiring board can be obtained by bonding the thus-obtained cover film-side semi-finished product to the base film-side semi-finished product.

The semi-finished product on the base film side is, for example, (A) a process of initially drying the coating film by applying a solution of a resin serving as the base film to the metal foil, and (B) heat treatment of the laminate of the metal foil obtained in (A) and the initial dry coating film. It is obtained by a manufacturing method including a drying process (hereinafter, referred to as a "heat treatment/desorption process").

For the formation of the circuit in the metal foil layer, a conventionally known method can be used. An active method may be used or a subtractive method may be used. Preferably, it is a subtractive method.

The obtained base film-side semi-finished product may be used as it is for bonding with the cover film-side semi-finished product, or may be used for bonding with the cover film-side semi-finished product after bonding and storing the release film.

The cover film side semi-finished product is manufactured by applying an adhesive to the cover film, for example. If necessary, a crosslinking reaction in the applied adhesive can be performed. In a preferred embodiment, the adhesive layer is semi-cured.

The obtained cover film-side semi-finished product may be used as it is for bonding to the substrate-side semi-finished product, or may be used for bonding to the base film-side semi-finished product after bonding and storing the release film.

The base film-side semi-finished product and the cover film-side semi-finished product are stored in the form of a roll, for example, and then bonded to produce a printed wiring board. As a method of bonding, any method can be used, and for example, it can be bonded using a press or a roll. In addition, both can be bonded while heating by a method such as using a heat press or a heating roll device.

The semi-finished product on the side of the reinforcing material is preferably manufactured by applying an adhesive to the reinforcing material in the case of a soft, windable reinforcing material such as a polyimide film. In addition, in the case of a reinforcing plate that cannot be wound tightly, such as a metal plate such as SUS or aluminum, or a plate in which glass fibers are cured with an epoxy resin, it is suitable to be manufactured by transfer coating an adhesive previously applied to a release substrate. Further, if necessary, a crosslinking reaction in the applied adhesive can be performed. In a preferred embodiment, the adhesive layer is semi-cured.

The obtained semi-finished product on the side of the reinforcing material may be directly used for bonding with the rear surface of the printed wiring board, or may be used for bonding with the base film side semi-finished product after bonding and storing the release film.

The base film side semi-finished product, the cover film side semi-finished product, and the reinforcing agent side semi-finished product are all laminates for printed wiring boards in the present invention.

<Example>

Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to the examples. In Examples and Comparative Examples, simply "part" indicates "mass part".

(Property evaluation method)

Acid (A) Component: Acid-modified polystyrene elastomer resin

The acid value (equivalent/10 ⁶ g) of the acid-modified polystyrene elastomer resin in the present invention was obtained by dissolving the acid-modified polystyrene elastomer resin in toluene, and phenolphthalein was titrated as an indicator with a methanol solution of sodium methoxide. It was expressed as an equivalent (equivalent/10 ⁶ g) in 1 ton of resin.

Weight average molecular weight (Mw)

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

(1) Peel strength (adhesion)

The adhesive composition described later was applied to a polyimide film having a thickness of 12.5 µm (manufactured by Kaneka, Apical) or an LCP film having a thickness of 25 µm (manufactured by Kuraray, Bexta), and the thickness after drying was 25. It was applied so as to become µm and dried at 130°C for 3 minutes. The adhesive film (B stage product) thus obtained was bonded to a rolled copper foil of 18 µm. Bonding was carried out by making the glossy surface of the rolled copper foil in contact with the adhesive, pressing at 160°C under 40 kgf/cm 2 pressure for 30 seconds, and bonding. Subsequently, it heat-treated and hardened|cured at 140 degreeC for 4 hours, and obtained the sample for peel strength evaluation. Peeling strength was 25°C, a 90° peeling test was performed at a film pull and a tensile rate of 50 mm/min, and the peel strength was measured. This test shows the adhesive strength at room temperature.

<Evaluation criteria>

◎: 1.0 N/mm or more

○: 0.8 N/mm or more and less than 1.0 N/mm

△: 0.5 N/mm or more and less than 0.8 N/mm

×: less than 0.5 N/mm

(2) Dry solder heat resistance

A sample was prepared in the same manner as above, and a 2.0 cm×2.0 cm sample piece was dried at 120° C. for 30 minutes, and flowed into the molten solder bath at each temperature for 1 minute to prevent swelling and other appearance changes. The temperature was measured.

<Evaluation criteria>

◎: 310℃ or higher

○: 300℃ or more and less than 310℃

△: 290℃ or more and less than 300℃

×: less than 290°C

(3) Relative permittivity (ε _c ) and dielectric loss tangent (tanδ)

The adhesive composition described later was applied to a glossy surface of an electrolytic copper foil having a thickness of 35 µm so that the thickness after drying and curing became 25 µm, and dried at 130°C for 3 minutes. Subsequently, it heat-treated at 140 degreeC for 4 hours, and it hardened|cured, and the copper clad laminated board for test was obtained. On the cured adhesive composition side of the obtained test copper clad laminate, an evaporated dry solid conductive silver paste was applied by screen printing in a circle with a diameter of 50 mm, dried and cured at 120° C. for 30 minutes, and further, in the center of the circle with the conductive silver paste. A lead wire having a length of 30 mm was bonded with a conductive adhesive to obtain a parallel plate capacitor. Measure the capacitance (Cap) and loss factor (D) (dielectric loss tangent) of the obtained parallel plate capacitor using a PRECISION LCR meter HP-4284A under the condition of a frequency of 1 MHz at 22°C, and the relative dielectric constant from the following equation: (ε _c ) was calculated.

ε _c =(Cap×d)/(S×ε ₀ )

Here Cap: capacitance [F]

d: dielectric layer thickness = 25×10 ^-6 [m]

S: the measured dielectric area ^{= π × (25 × 10 -} 3) 2

ε ₀ : Vacuum dielectric constant 8.854×10 ^-12

to be.

The obtained relative permittivity and dielectric loss tangent were evaluated as follows.

<Relative dielectric constant evaluation criteria>

◎: 2.3 or less

○: more than 2.3 and less than 2.6

△: more than 2.6 and less than 3.0

×: more than 3.0

<Evaluation criteria for genetic loss tangent>

◎: 0.005 or less

○: more than 0.005 0.01 or less

△: more than 0.01 and less than 0.02

×: more than 0.02

(4) Port Life

A solvent-soluble resin (acid-modified polystyrene elastomer resin), which is the main resin of the adhesive composition of the present invention, was heated and dissolved in toluene at 70° C. so that the solid content concentration became 20% by mass to obtain a solvent-soluble resin varnish (main product). This solvent-soluble resin varnish was measured for dispersion viscosity at 25°C using a Brookfield viscometer, and the initial dispersion viscosity (ηB0) was determined. Thereafter, the solvent-soluble resin varnish was stored in a stationary state at 5°C for 7 days, and the solution viscosity (ηB) was measured at 25°C. The solution viscosity ratio was calculated by the following formula, and evaluated as follows.

Solution viscosity ratio = solution viscosity (ηB)/solution viscosity (ηB0)

<Evaluation criteria>

◎: 0.5 or more and less than 1.5

○: 1.5 or more and less than 2.0

△: 2.0 or more and less than 3.0

×: 3.0 or more, or not possible to measure the viscosity by purifying

(Production of topic 1)

In a 500 ml four-neck flask equipped with a water-cooled reflux condenser and a stirrer, 100 parts by mass of acid-modified polystyrene elastomer resin (Tuftec (registered trademark) M1911) and 400 parts by mass of toluene were added, and the temperature was raised to 70° C. It dissolved by continuing stirring for 1 hour. Table 1 shows the pot life properties of Subject 1 obtained by cooling.

(Production of topics 2 to 8)

The acid-modified polystyrene elastomer resin (A) was changed to the one shown in Table 1, and Subjects 2 to 8 were produced in the same manner as in Subject 1. Table 1 shows the blending amount and pot life.

Example One

500 parts by mass of the subject 1, 5 parts by mass of carbodiimide resin V-05, and 10 parts by mass of the epoxy resin HP-7200 were blended as a crosslinking agent to obtain an adhesive composition. Table 2 shows the blending amount, adhesive strength, solder heat resistance, and electrical properties.

Example 2-10

Subjects 2 to 4 and crosslinking agents were changed as shown in Table 2, and Examples 2 to 10 were carried out in the same manner as in Example 1. Table 2 shows adhesive strength, solder heat resistance, and electrical properties.

Comparative example 1-6

Subjects 2 and 5 to 8 and crosslinking agents were changed as shown in Table 3, and Comparative Examples 1 to 6 were carried out in the same manner as in Example 1. Table 3 shows adhesive strength, solder heat resistance, and electrical properties. However, the subject 5 and 6 were in a bad solution state and became a gel, so they were reheated to 70°C and evaluated as adhesives.

The polyolefin resin, acid-modified polystyrene elastomer resin (A), carbodiimide resin (B), and epoxy resin (C) used in Tables 1 to 3 are as follows.

Acid-modified polystyrene elastomer resin: Tuftec (registered trademark) M1911 (manufactured by Asahi Kasei Chemical), acid value of 37 equivalents/10 ⁶ g

Acid-modified polystyrene elastomer resin: Tuftec (registered trademark) M1913 (manufactured by Asahi Kasei Chemical), acid value 185 equivalents/10 ⁶ g

Acid-modified polystyrene elastomer resin: Tuftec (registered trademark) M1943 (manufactured by Asahi Kasei Chemical), acid value 185 equivalents/10 ⁶ g

Polystyrene styrene elastomer resin: Septon (registered trademark) 8007L (manufactured by Kurare), acid value 0 equivalent/10 ⁶ g

Carboxyl group-containing acrylonitrile butadiene rubber NBR (manufactured by JSR Co., Ltd.)

Carbodiimide resin: V-05 (manufactured by Nisshinbo Chemical)

Carbodiimide resin: V-03 (manufactured by Nisshinbo Chemical)

o-cresol novolac type epoxy resin: YDCN-700-3 (manufactured by Shinnittetsu Sumikin Chemical Co., Ltd.)

Dicyclopentadiene type epoxy resin: HP-7200 (manufactured by DIC)

(Acid-modified polyolefin resin CO-1)

Manufacturing example One

In a 1 L autoclave, 100 parts by mass of a propylene-butene copolymer ("Tafmer (registered trademark) XM7080" manufactured by Mitsui Chemicals), 150 parts by mass of toluene and 19 parts by mass of maleic anhydride, di-tert-butyl peroxide 6 After adding mass parts and raising the temperature to 140°C, the mixture was stirred for further 3 hours. Then, after cooling the obtained reaction liquid, it poured into a container containing a large amount of methyl ethyl ketone, and the resin was deposited. Thereafter, the liquid containing the resin was centrifuged to separate and purify an acid-modified propylene-butene copolymer obtained by graft polymerization of maleic anhydride, maleic anhydride, and a low molecular weight substance. Thereafter, by drying under reduced pressure at 70° C. for 5 hours, maleic anhydride-modified propylene-butene copolymer (CO-1, acid value of 410 equivalents/10 ⁶ g, weight average molecular weight of 60,000, Tm 80°C, ΔH 35 J/g ).

As is evident from Tables 1 and 2, in Examples 1 to 10, the main pot life properties were excellent, and as an adhesive, a liquid crystal polymer (PI) and copper foil had excellent adhesion and dry solder heat resistance, LCP) and copper foil have excellent adhesion and dry solder heat resistance. In addition, the electrical properties of the adhesive composition are low and good in both the relative dielectric constant and dielectric loss tangent. In contrast, as is clear from Table 1, in the main subjects 5 and 6, the pot life properties of the main subjects are poor due to crystallization of the polyolefin resin. In Comparative Example 1, since no carbodiimide resin was blended, the interaction with the LCP interface was small, and the adhesive strength was low. In Comparative Example 2, since the epoxy resin was not blended, the crosslinking density was low, and the dry solder heat resistance was inferior. In Comparative Example 3, the adhesive properties were excellent, but the pot life of the subject 5 was inferior. In Comparative Example 4, since the acid-modified polystyrene elastomer resin was not blended, the adhesive strength was inferior. Also, the port life of topic 6 is lagging behind. In Comparative Example 5, since the polystyrene elastomer resin is not acid-modified (it does not contain a carboxyl group), the crosslinking density is low, and the dry solder heat resistance is inferior. In Comparative Example 6, since the acid-modified polystyrene elastomer resin was not blended, the low dielectric properties of the adhesive composition were inferior.

According to the present invention, a resin substrate having low dielectric properties such as LCP, as well as a conventional polyimide and polyethylene terephthalate film, and a metal substrate such as copper foil have high adhesion, and high solder heat resistance can be obtained. , In addition, it is possible to obtain an adhesive composition, an adhesive sheet, and a laminate bonded using the same, which are excellent in low dielectric properties and pot life properties. Due to the above characteristics, it is useful for flexible printed wiring board applications, particularly in FPC applications requiring low dielectric properties (low dielectric constant, low dielectric loss tangent) in a high frequency region.

Claims (5)

An adhesive composition containing an acid-modified polystyrene elastomer resin (A), a carbodiimide resin (B) and an epoxy resin (C) and satisfying the following (1) to (4):
(1) The cured product of the adhesive composition has a relative dielectric constant (ε _c ) of 3.0 or less at a frequency of 1 MHz.
(2) The dielectric loss tangent (tanδ) at a frequency of 1 MHz of the cured product of the adhesive composition is 0.02 or less.
(3) The 90° peeling strength of the laminate obtained by bonding the liquid crystal polymer film and copper foil with the adhesive composition is 0.5 N/mm or more.
(4) The solution viscosity ratio (solution viscosity (ηB)/solution viscosity (ηB0)) of the toluene solution (solid content concentration 20% by mass) of the acid-modified polystyrene elastomer resin (A) is 0.5 or more and less than 3.0.
Solution viscosity (ηB0): Solution viscosity at 25°C immediately after dissolving the acid-modified polystyrene elastomer resin (A) in toluene,
Solution viscosity (ηB): The solution viscosity at 25°C after dissolving the acid-modified polystyrene elastomer resin (A) in toluene and standing still at 5°C for 7 days. The method of claim 1,
With respect to 100 parts by mass of the acid-modified polystyrene elastomer resin (A), the content of the carbodiimide resin (B) is 0.1 to 30 parts by mass, and with respect to 100 parts by mass of the acid-modified polystyrene elastomer resin (A), the epoxy resin (C) Adhesive composition having a content of 1 to 30 parts by mass. An adhesive sheet containing the adhesive composition according to claim 1 or 2. A laminate comprising the adhesive composition according to claim 1 or 2. A printed wiring board comprising the laminate according to claim 4 as a component.