KR20230158031A - Adhesive composition, adhesive sheet containing the same, laminate, and printed wiring board - Google Patents

Abstract

[Problem] To provide an adhesive composition with excellent heat resistance, adhesive strength, low relative permittivity and dielectric loss tangent, and excellent dielectric properties, and adhesive sheets, laminates, and printed wiring boards containing the same.
[Solution] An adhesive composition comprising a polyester resin, compound A, and compound B.
Compound A: A compound having a terminal unsaturated hydrocarbon group and a 5% weight loss temperature of 260°C or higher.
Compound B: Compound having an epoxy group and a terminal unsaturated hydrocarbon group

Description

Adhesive composition, adhesive sheet containing the same, laminate, and printed wiring board

The present invention relates to adhesive compositions. More specifically, it relates to an adhesive composition used for adhesion between a resin substrate and a resin substrate or a metal substrate. In particular, it relates to an adhesive composition for flexible printed wiring boards (hereinafter abbreviated as FPC), adhesive sheets, laminates, and printed wiring boards containing the same.

Copolymerized polyester is widely used as a raw material for resin compositions used in coatings, inks, adhesives, etc., and is generally composed of polyhydric carboxylic acid and polyhydric alcohol. Flexibility and molecular weight can be freely controlled by selection and combination of polyhydric carboxylic acid and polyhydric alcohol.

Copolyester has excellent adhesion to metals containing copper, and has also been used in adhesives such as FPC by mixing a curing agent such as epoxy resin (for example, patent document 1).

Because FPC has excellent flexibility, it can respond to multi-functionality and miniaturization of personal computers (PCs) and smart phones, and is widely used to embed electronic circuit boards in narrow and complex interiors. In recent years, electronic devices have become smaller, lighter, more dense, and have higher output, and requirements for the performance of wiring boards (electronic circuit boards) have become increasingly high. In particular, to increase the transmission speed in FPC, high frequency signals are being used. Accordingly, the demand for low dielectric properties (low dielectric constant, low dielectric loss tangent) in the high frequency range is increasing for FPC. In order to achieve such low dielectric properties, measures are being taken to reduce the dielectric loss of FPC substrates and adhesives, and the substrates used in FPC are not only conventional polyimide (PI) and polyethylene terephthalate (PET). , Base films such as liquid crystal polymer (LCP) and syndiotactic polystyrene (PS) with low dielectric properties have been proposed. As an adhesive, the development of an adhesive using polyphenylene ether (patent document 2) is in progress.

Patent Document 1: Japanese Patent Publication No. 6-104813 Patent Document 2: WO 2020/196718 Publication

However, the copolyester described in Patent Document 1 has a high relative dielectric constant and dielectric loss tangent, and does not have the low dielectric properties described above, so it is not suitable for FPC in the high frequency region. Additionally, the adhesive described in Patent Document 2 is hardly said to have excellent heat resistance as an FPC adhesive, and its dielectric properties are also insufficient.

The present invention was made against the background of these prior art problems. That is, the object of the present invention is to provide an adhesive composition with excellent heat resistance, excellent adhesive strength, low relative dielectric constant and dielectric loss tangent, and excellent dielectric properties, and an adhesive sheet, a laminate, and a printed wiring board containing the same.

As a result of intensive studies, the present inventors have discovered that the above problems can be solved by means shown below, and have arrived at the present invention.

That is, the present invention includes the following configurations.

[1] An adhesive composition comprising a polyester resin, compound A, and compound B.

Compound A: A compound having a terminal unsaturated hydrocarbon group and a 5% weight loss temperature of 260°C or higher.

Compound B: Compound having an epoxy group and a terminal unsaturated hydrocarbon group

[2] The adhesive composition of [1] above, wherein the compound A is a compound having an aromatic ring structure or an alicyclic structure as a structural unit.

[3] The adhesive composition of [1] above, wherein the compound A is a polyphenylene ether or phenol resin having a terminal unsaturated hydrocarbon group.

[4] The adhesive composition of the above [1] to [3], wherein the compound B is a compound having an isocyanurate ring.

[5] The adhesive composition of the above [1] to [4], wherein the dielectric loss tangent of the polyester resin is 0.005 or less.

[6] The adhesive composition of the above [1] to [5] further comprising polycarbodiimide.

[7] An adhesive sheet having an adhesive layer containing the adhesive composition of the above [1] to [6].

[8] A laminate having an adhesive layer containing the adhesive composition of the above [1] to [6].

[9] A printed wiring board comprising the laminate of [8] above as a component.

The adhesive composition of the present invention is excellent in dielectric properties, adhesive strength, and solder heat resistance. For this reason, it is suitable for adhesives for printed wiring boards, adhesive sheets, laminates, and printed wiring boards in the high frequency range.

Hereinafter, one embodiment of the present invention will be described in detail below. However, the present invention is not limited to this, and can be implemented with various modifications within the scope already described.

<Adhesive composition>

The adhesive composition of the present invention is an adhesive composition comprising a polyester resin, compound A, and compound B. Here, Compound A and Compound B are each of the following compounds.

Compound A: A compound having a terminal unsaturated hydrocarbon group and a 5% weight loss temperature of 260°C or higher.

Compound B: Compound having an epoxy group and a terminal unsaturated hydrocarbon group

When the terminal unsaturated hydrocarbon groups of Compound A and Compound B react with each other, curing can be achieved without generating hydroxyl groups that deteriorate the dielectric properties, and thus excellent solder heat resistance and dielectric properties can be achieved at the same time.

<Polyester resin>

The polyester resin in the present invention contains a chemical structure obtained by polycondensation of a polyhydric carboxylic acid component and a polyhydric alcohol component, and the polyhydric carboxylic acid component and the polyhydric alcohol component are each one or two or more selected components. It includes.

As the polyhydric carboxylic acid component constituting the polyester resin of the present invention, it is preferable that it is aromatic polyhydric carboxylic acid or cycloaliphatic polyhydric carboxylic acid, and it is more preferable that it is aromatic dicarboxylic acid or cycloaliphatic dicarboxylic acid. Excellent dielectric properties can be exhibited by using only an aromatic polyhydric carboxylic acid component or an alicyclic polyhydric carboxylic acid component as the polyhydric carboxylic acid component.

The aromatic dicarboxylic acid component is not particularly limited, but includes terephthalic acid, isophthalic acid, orthophthalic acid, 4,4'-dicarboxybiphenyl, 5-sodium sulfoisophthalic acid, naphthalenedicarboxylic acid, or esters thereof. You can use it. Preferably, it is naphthalenedicarboxylic acid, and it can exhibit excellent dielectric properties. More preferably, the polyester resin contains 50 mol% or more of naphthalenedicarboxylic acid, more preferably 70 mol% or more, and particularly preferably 80 mol% or more of naphthalenedicarboxylic acid as the polyhydric carboxylic acid component constituting the polyester resin, thereby improving the dielectric properties. can be improved.

The cycloaliphatic dicarboxylic acid is not particularly limited, but includes 1,4-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, tetrahydrophthalic acid, methyltetrahydrophthalic acid, tetrahydrophthalic anhydride, and methyl. Tetrahydrophthalic anhydride, hydrogenated naphthalenedicarboxylic acid, etc. can be used.

The polyhydric alcohol constituting the polyester resin in the present invention is not particularly limited, but includes ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1 ,4-butanediol, 2-methyl-1,3-propanediol, neopentyl glycol, 1,5-pentanediol, 3-methyl-1,5-pentanediol, 1,6-hexanediol, 1,8-octane Diol, 2-methyl-2-ethyl-1,3-propanediol, 2,2-diethyl-1,3-propanediol, 2-ethyl-2-n-propyl-1,3-propanediol, 2, 2-di-n-propyl-1,3-propanediol, 2-n-butyl-2-ethyl-1,3-propanediol, 2,2-di-n-butyl-1,3-propanediol, 2 , Aliphatic polyhydric alcohols such as 4-diethyl-1,5-pentanediol, 2-ethyl-1,3-hexanediol, and dimer diol, and alicyclic alcohols such as 1,4-cyclohexanedimethanol and tricyclodecane dimethanol. Polyalkylene ether glycols such as polyhydric alcohols, polytetramethylene glycol, and polypropylene glycol can be used, and among these, one type or two or more types can be used. Preferably, it is dimerdiol or tricyclodecane dimethanol, and can exhibit excellent dielectric properties. More preferably, the total amount of dimerdiol and tricyclodecane dimethanol as the polyhydric alcohol component constituting the polyester resin is 20 mol% or more, more preferably 30 mol% or more, and particularly preferably 40 mol% or more. , dielectric properties can be improved. Dimerdiol and tricyclodecane dimethanol may contain only one or both of them.

The polyester resin in the present invention may be copolymerized with a trivalent or higher polyhydric carboxylic acid component and/or a trivalent or higher polyhydric alcohol component. Examples of trivalent or higher polyvalent carboxylic acid components include aromatic carboxylic acids such as trimellitic acid, pyromellitic acid, benzophenonetetracarboxylic acid, trimesic acid, trimellitic anhydride (TMA), and pyromellitic anhydride (PMDA). Acids, aliphatic carboxylic acids such as 1,2,3,4-butanetetracarboxylic acid, etc. may be used, and one or two or more types of these may be used. Examples of trihydric or higher polyhydric alcohol components include glycerin, trimethylolpropane, trimethylolethane, pentaerythritol, α-methylglucose, mannitol, and sorbitol, and one or two or more types can be used. . However, if the amount of copolymerization of the trivalent or higher polyhydric carboxylic acid component and/or the trihydric or higher polyhydric alcohol component is undesirable, the dielectric properties of the polyester resin may deteriorate.

As a method of the polymerization condensation reaction for producing the polyester resin of the present invention, for example, 1) heating a polyhydric carboxylic acid and a polyhydric alcohol in the presence of a known catalyst, going through a dehydration esterification step, and performing a depolyhydric alcohol/polycondensation reaction. 2) a method of heating the alcohol ester form of a polyhydric carboxylic acid and a polyhydric alcohol in the presence of a known catalyst, performing a transesterification reaction, and then performing a depolyhydric alcohol/polycondensation reaction; 3) a method of performing depolymerization. . In the methods 1) and 2) above, part or all of the acid component may be replaced with an acid anhydride.

When producing the polyester resin in the present invention, conventionally known polymerization catalysts, such as titanium compounds such as tetra-n-butyl titanate, tetraisopropyl titanate, and titanium oxyacetylcetonate, antimony trioxide, and tributium, are used. Antimony compounds such as oxyantimony, germanium compounds such as germanium oxide and tetra-n-butoxygermanium, and acetates such as magnesium, iron, zinc, manganese, cobalt, and aluminum can be used. These catalysts can be used alone or in combination of two or more types.

The number average molecular weight of the polyester resin in the present invention is preferably 5,000 or more, and more preferably 10,000 or more. Moreover, it is preferable that it is 100000 or less, more preferably 50000 or less, and even more preferably 30000 or less. If it is within the above range, it is preferable because it is easy to handle when dissolved in a solvent and has excellent dielectric properties.

The polyester resin in the present invention preferably has a dielectric loss tangent of 0.005 or less at 10 GHz. Preferably it is 0.004 or less, more preferably 0.003 or less. The lower limit is not particularly specified, but in practical terms, it is 0.001 or more. In order to keep the dielectric loss tangent of the polyester resin within the above range, as described above, a method of including naphthalenedicarboxylic acid, dimerdiol, or tricyclodecane dimethanol as a structural unit of the polyester resin can be used.

<Compound A>

Compound A in the present invention is a compound that has a terminal unsaturated hydrocarbon group and has a 5% weight loss temperature of 260°C or higher. By having a terminal unsaturated hydrocarbon group, the crosslinking density can be increased through reaction with the latter compound B, and the solder heat resistance can be improved. Additionally, since it does not generate hydroxyl groups that deteriorate dielectric properties after reaction, it can be used as an adhesive with excellent dielectric properties. It is preferable to have two or more terminal unsaturated hydrocarbon groups per molecule because the crosslinking density can be further increased. Here, the terminal unsaturated hydrocarbon group refers to a group having a structure of CH ₂ =C, such as a vinyl group, vinylidene group, allyl group, acrylic group, methacryl group, and styrene group.

The 5% weight loss temperature of Compound A is required to be 260°C or higher. Preferably it is 270°C or higher, more preferably 280°C or higher, and even more preferably 290°C or higher. When the 5% weight loss temperature is above the above value, it becomes possible to perform soldering without causing appearance defects even at temperatures exceeding the melting point of the solder.

Compound A preferably has an aromatic ring structure or an alicyclic structure as a structural unit. By having an aromatic ring structure or an alicyclic structure as a structural unit, solder heat resistance can be improved and dielectric properties are also excellent. Among these, those having an aromatic ring structure or an alicyclic structure as the skeleton of Compound A are preferable, and polyphenylene ether or phenol resin is preferable. Specific examples of polyphenylene ethers having terminal unsaturated hydrocarbon groups include SA-9000 from SABIC and OPE-2St from Mitsubishi Chemical Corporation. Additionally, examples of the phenol resin having a terminal unsaturated hydrocarbon group include Resitop FTC-809AE manufactured by Kunei Chemical Industries.

The number average molecular weight of Compound A is preferably 500 or more, more preferably 1000 or more. Additionally, it is preferably 100,000 or less, more preferably 10,000 or less, and even more preferably 5,000 or less. If it is within the above range, the solubility in the solvent is good and a uniform adhesive coating film can be formed.

The content of compound A in the adhesive composition of the present invention is preferably 1 part by mass or more, more preferably 10 parts by mass or more, per 100 parts by mass of the polyester resin. Additionally, it is preferably 100 parts by mass or less, and more preferably 50 parts by mass or less. If it is within the above range, both excellent adhesiveness and solder heat resistance can be achieved.

<Compound B>

Compound B in the present invention is a compound having an epoxy group and a terminal unsaturated hydrocarbon group. By having an epoxy group, it can be reacted with polyester resin or polycarbodiimide (described later), and by having a terminal unsaturated hydrocarbon group, it can be reacted with compound A. By increasing the crosslinking density between these compounds, excellent solder heat resistance is achieved. It can be realized. Here, the terminal unsaturated hydrocarbon group refers to a group having a structure of CH ₂ =C, such as a vinyl group, vinylidene group, allyl group, acrylic group, methacryl group, and styrene group.

Compound B preferably has a ring structure. If compound B has a ring structure, heat resistance can be improved and dielectric properties are also excellent. The ring structure that Compound B has is preferably an aromatic ring structure or an isocyanuric ring structure from the viewpoint of heat resistance. Specific examples of such compound B include diallyl monoglycidyl isocyanurate and diglycidyl monoallyl isocyanurate. By using these, the crosslinking density can be increased and solder heat resistance can be improved.

The molecular weight of compound B is preferably 500 or less. More preferably, it is 400 or less. When the molecular weight is below the above value, solubility in solvents and reactivity with compound A, polyester resin, and polycarbodiimide become good, and crosslinking density can be increased, thereby improving solder heat resistance.

The content of compound B in the adhesive composition of the present invention is preferably 0.1 part by mass or more, more preferably 1 part by mass or more, with respect to 100 parts by mass of the polyester resin. Additionally, it is preferably 50 parts by mass or less, and more preferably 20 parts by mass or less. If it is within the above range, both excellent adhesiveness and solder heat resistance can be achieved. Additionally, the content of compound B is preferably 1 equivalent or more of terminal unsaturated hydrocarbon groups relative to the terminal unsaturated hydrocarbon groups of compound A. By setting it to 1 equivalent or more, the crosslinking density can be increased and excellent solder heat resistance can be exhibited.

<Radical generator>

The adhesive composition of the present invention also preferably contains a radical generator. The adhesive composition of the present invention can cause Compound A and Compound B to react by heating, but the radicals generated by the radical generator efficiently cause the terminal unsaturated hydrocarbon groups of Compound A and Compound B to react with each other, thereby increasing the crosslinking density. , solder heat resistance and dielectric properties can be improved. The radical generator is not particularly limited, but it is preferable to use an organic peroxide. Organic peroxides are not particularly limited, but include di-tert-butylperoxyphthalate, tert-butylhydroperoxide, dicumyl peroxide, benzoyl peroxide, tert-butylperoxybenzoate, and tert-butylperoxy-2-ethyl. Peroxides such as hexanoate, tert-butyl peroxypivalate, methyl ethyl ketone peroxide, di-tert-butyl peroxide, and lauroyl peroxide; Azonitriles, such as azobisisobutyronitrile and azobisisopropionitrile, can be mentioned.

The 1-minute half-life temperature of the radical generator used in the present invention is preferably 140°C or higher. By setting the temperature to 140°C or higher, the solvent in the adhesive composition varnish is volatilized to prevent a radical reaction from starting when creating an adhesive sheet, and excellent adhesiveness can be exhibited.

The amount of the radical generator used in the present invention is preferably 0.1 part by mass or more, more preferably 1 part by mass or more, per 100 parts by mass of Compound A. Additionally, it is preferably 50 parts by mass or less, and more preferably 10 parts by mass or less. By keeping it within the above range, an appropriate crosslinking density can be achieved, and both adhesiveness and solder heat resistance can be achieved.

<Polycarbodiimide>

The adhesive composition of the present invention may contain polycarbodiimide. Polycarbodiimide is not particularly limited as long as it has two or more carbodiimide bonds in the molecule. By using polycarbodiimide, the hydroxyl group of the polyester resin reacts with the carbodiimide bond, and heat resistance and adhesiveness can be improved. In addition, it also contributes to the improvement of dielectric properties by eliminating hydroxyl groups through reaction with the hydroxyl groups of the polyester resin.

In the adhesive composition of the present invention, the content of polycarbodiimide is preferably 1 part by mass or more, more preferably 3 parts by mass or more, per 100 parts by mass of the polyester resin. By exceeding the above lower limit, the crosslinking density can be increased, and the solder heat resistance becomes good. Moreover, it is preferably 20 parts by mass or less, and more preferably 10 parts by mass or less. By setting it below the above upper limit, excellent solder heat resistance and low dielectric properties can be achieved. That is, by keeping it within the above range, an adhesive composition having excellent solder heat resistance and low dielectric properties can be obtained.

<Epoxy Resin>

The adhesive composition of the present invention may contain an epoxy resin. The epoxy resin used in the present invention is not particularly limited as long as it has an epoxy group in the molecule, but preferably has two or more epoxy groups in the molecule. Specifically, although not specifically limited, biphenyl type epoxy resin, naphthalene type epoxy resin, bisphenol A type epoxy resin, bisphenol F type epoxy resin, novolak type epoxy resin, alicyclic epoxy resin, dicyclopentadiene type epoxy resin. , tetraglycidyldiaminodiphenylmethane, triglycidylparaminophenol, tetraglycidylbisaminomethylcyclohexanone, N,N,N',N'-tetraglycidyl-m-xylenediamine, and At least one selected from the group consisting of epoxy-modified polybutadiene can be used. Preferably, it is N,N,N',N'-tetraglycidyl-m-xylenediamine, biphenyl-type epoxy resin, novolac-type epoxy resin, dicyclopentadiene-type epoxy resin, or epoxy-modified polybutadiene. More preferably, it is N,N,N',N'-tetraglycidyl-m-xylenediamine, and it can exhibit excellent adhesiveness.

In the adhesive composition of the present invention, the content of the epoxy resin is preferably 0.1 part by mass or more, more preferably 0.5 part by mass or more, and still more preferably 1 part by mass or more, based on 100 parts by mass of the polyester resin. . By exceeding the above lower limit, a sufficient curing effect can be obtained and excellent adhesiveness and solder heat resistance can be exhibited. Additionally, it is preferably 10 parts by mass or less, and more preferably 5 parts by mass or less. By setting it below the above upper limit, pot life and low dielectric properties become good. That is, by keeping it within the above range, it is possible to obtain an adhesive composition having excellent low dielectric properties in addition to adhesiveness, solder heat resistance, and pot life properties.

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 polyester resin, compound A, and compound B. 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 trichlorohydrocarbons. Halogenated hydrocarbons such as ethylene, dichloroethylene, chlorobenzene, and chloroform, alcohol-based solvents such as methanol, ethanol, isopropyl alcohol, butanol, pentanol, hexanol, propanediol, and phenol, acetone, methyl isobutyl ketone, and methyl ethyl ketone. , ketone solvents such as pentanone, hexanone, cyclohexanone, isophorone, and acetophenone, cellosolves such as methyl cellosolve and ethyl cellosolve, methyl acetate, ethyl acetate, butyl acetate, methyl propionate, and formic acid. Ester solvents such as butyl, ethylene glycol monon-butyl ether, ethylene glycol monoiso-butyl ether, ethylene glycol monotert-butyl ether, diethylene glycol monon-butyl ether, diethylene glycol monoiso-butyl ether, tri. Glycol ether-based solvents such as ethylene glycol monon-butyl ether and tetraethylene glycol monon-butyl ether can be used, and one or two or more of these can be used in combination. In particular, methylcyclohexane and toluene are preferable from the viewpoint of work environment and drying properties.

The organic solvent is preferably in the range of 100 to 1000 parts by mass based on 100 parts by mass of the polyester resin. By exceeding the above lower limit, the liquid form and pot life properties become good. Additionally, setting it below the above upper limit becomes advantageous in terms of manufacturing costs and transportation costs.

Additionally, the adhesive composition of the present invention may further contain other components as needed. Specific examples of such components include flame retardants, tackifiers, fillers, and silane coupling agents.

<Flame retardant>

A flame retardant may be added to the adhesive composition of the present invention as needed. Examples of flame retardants include bromine-based, phosphorus-based, nitrogen-based, and hydroxide metal compounds. Among them, phosphorus-based flame retardants are preferable, and known phosphorus-based flame retardants such as phosphoric acid esters such as trimethyl phosphate, triphenyl phosphate, tricresyl phosphate, etc., phosphates such as aluminum phosphinate, and phosphazene can be used. These may be used individually, or two or more types may be used in arbitrary combination. When containing a flame retardant, the flame retardant is preferably contained in the range of 1 to 200 parts by mass, more preferably in the range of 5 to 150 parts by mass, based on a total of 100 parts by mass of the polyester resin, compound A, and compound B. The range of ∼100 parts by mass is most preferred. By keeping it within the above range, flame retardancy can be achieved while maintaining adhesiveness, solder heat resistance, and electrical properties.

<Tackifier>

A tackifier may be added to the adhesive composition of the present invention as needed. Examples of tackifiers include polyterpene resins, rosin-based resins, aliphatic-based petroleum resins, alicyclic-based 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 individually, or two or more types may be used in arbitrary combination. When containing a tackifier, it is preferably contained in the range of 1 to 200 parts by mass, more preferably in the range of 5 to 150 parts by mass, based on a total of 100 parts by mass of the polyester resin, compound A, and compound B. The range of ∼100 parts by mass is most preferred. By keeping it within the above range, the effect of the tackifier can be exhibited while maintaining adhesiveness, solder heat resistance, and electrical properties.

<Filler>

Fillers may be added to the adhesive composition of the present invention as needed. Examples of the organic filler include powders of heat-resistant resins such as polyimide, polyamidoimide, fluororesin, and liquid crystal polyester. Additionally, inorganic fillers include, for example, silica (SiO ₂ ), alumina (Al ₂ O ₃ ), titania (TiO ₂ ), tantalum oxide (Ta ₂ O ₅ ), zirconia (ZrO ₂ ), and silicon nitride (Si ₃ N ₄ ). , boron nitride (BN), calcium carbonate (CaCO ₃ ), calcium sulfate (CaSO ₄ ), zinc oxide (ZnO), magnesium titanate (MgO·TiO ₂ ), barium sulfate (BaSO ₄ ), organic bentonite, clay, mica, Examples include aluminum hydroxide and magnesium hydroxide, and among these, silica is preferable due to ease of dispersion and the effect of improving heat resistance.

Hydrophobic silica and hydrophilic silica are generally known as silica, but here, hydrophobic silica treated with dimethyldichlorosilane, hexamethyldisilazane, octylsilane, etc. is preferred for imparting hygroscopic resistance. When blending silica, the blending amount is preferably 0.05 to 30 parts by mass based on a total of 100 parts by mass of the copolyester, compound A, and compound B. By exceeding the above lower limit, additional heat resistance can be achieved. Moreover, by setting it below the above upper limit, poor dispersion of silica and excessively high solution viscosity are suppressed, and workability becomes good.

<Silane coupling agent>

A silane coupling agent may be added to the adhesive composition of the present invention as needed. It is very desirable because the adhesion to metal and heat resistance characteristics are improved by mixing a silane coupling agent. The silane coupling agent is not particularly limited, but includes those having an unsaturated group, those having an epoxy group, and those having an amino group. Among these, from the viewpoint of heat resistance, γ-glycidoxypropyltrimethoxysilane, β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, or β-(3,4-epoxycyclohexyl)ethyltriethoxysilane. Silane coupling agents having epoxy groups such as these are more preferable. When blending a silane coupling agent, the blending amount is preferably 0.5 to 20 parts by mass based on a total of 100 parts by mass of the polyester resin, compound A, and compound B. By keeping it within the above range, solder heat resistance and adhesiveness can be improved.

<Laminate>

The laminate of the present invention is one in which an adhesive composition is laminated on a base material (a two-layer laminate of a base material/adhesive layer), or a base material is further bonded together (a three-layer laminate of a base material/adhesive layer/substrate). Here, the adhesive layer refers to a layer of the adhesive composition after applying the adhesive composition of the present invention to a substrate and drying it. The laminate of the present invention can be obtained by applying the adhesive composition of the present invention to various substrates, drying them, and further laminating other substrates according to a conventional method.

<Description>

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 may include resin substrates such as film-type resins, metal substrates such as metal plates and metal foil, and paper. I can hear it.

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

As the metal substrate, any conventionally known conductive material that can be used for circuit boards can be used. Examples of materials include various metals such as SUS, copper, aluminum, iron, steel, zinc, and nickel, as well as respective alloys, plated products, and metals treated with other metals such as zinc and chromium compounds. Metal foil is preferable, and copper foil is more preferable. There is no particular limitation on the thickness of the metal foil, but it is preferably 1 μm or more, more preferably 3 μm or more, and still more preferably 10 μm or more. Also, it is preferably 50 μm or less, more preferably 30 μm or less, and even more preferably 20 μm or less. When the thickness is too thin, it may be difficult to obtain sufficient electrical performance of the circuit, while on the other hand, when the thickness is too thick, processing efficiency during circuit production may decrease. Metal foil is usually provided in roll form. The form of the metal foil used when manufacturing the printed wiring board of the present invention is not particularly limited. When using a ribbon-shaped metal foil, its length is not particularly limited. Additionally, the width is not particularly limited, but is preferably about 250 to 500 cm. The surface roughness of the substrate is not particularly limited, but is preferably 3 μm or less, more preferably 2 μm or less, and still more preferably 1.5 μm or less. Also, for practical purposes, it is preferably 0.3 μm or more, more preferably 0.5 μm or more, and still more preferably 0.7 μm or more.

Examples of paper include fine paper, kraft paper, roll paper, and glassine paper. Additionally, examples of composite materials include glass epoxy and the like.

In terms of adhesion and durability with the adhesive composition, the substrates include polyester resin, polyamide resin, polyimide resin, polyamideimide resin, liquid crystal polymer, polyphenylene sulfide, syndiotactic polystyrene, polyolefin resin, fluorine resin, and SUS. Steel sheet, copper foil, aluminum foil, or glass epoxy are preferred.

<Adhesive sheet>

In the present invention, the adhesive sheet is a product in which the above-described laminate and the release base material are laminated using an adhesive composition. Specific structural aspects include a laminate/adhesive layer/mold release base material, or a release base material/adhesive layer/laminated body/adhesive layer/mold release base material. By laminating the release substrate, it functions as a protective layer for the substrate. Additionally, by using a 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.

The adhesive sheet of the present invention can be obtained by applying the adhesive composition of the present invention to various laminates and drying them according to a conventional method. In addition, if a release base material is attached to the adhesive layer after drying, it can be rolled up without causing contamination to the base material, which improves operability. Since the adhesive layer is protected, it has excellent preservability and is easy to use. Additionally, after application and drying on a release substrate, it is possible to transfer the adhesive layer itself to another substrate by attaching another release substrate as needed.

<Modified base material>

The release substrate is not particularly limited, but for example, an application layer of a sealer such as clay, polyethylene, or polypropylene is provided on both sides of paper such as fine paper, kraft paper, roll paper, or glassine paper, and each application layer is further applied. Examples include those on which a silicone-based, fluorine-based, or alkyd-based mold release agent is applied. In addition, the release agent may be applied alone on various olefin films such as polyethylene, polypropylene, ethylene-α-olefin copolymer, propylene-α-olefin copolymer, and on films such as polyethylene terephthalate. For reasons such as the release force of the release base material and the adhesive layer and the adverse effects of silicone on electrical properties, polypropylene sealing was applied to both sides of the high-quality paper and an alkyd-based release agent was used on top, or an alkyd-based release agent was used on polyethylene terephthalate. It is preferable to use a mold release agent.

In addition, the method for coating the adhesive composition on the substrate in the present invention is not particularly limited, and includes a comma coater, reverse roll coater, and the like. Alternatively, if necessary, an adhesive layer can be provided directly or by transfer method on rolled copper foil or polyimide film, which are constituent materials of the printed wiring board. The thickness of the adhesive layer after drying is changed as necessary, but is preferably in the range of 5 to 200 μm. Sufficient adhesive strength can be obtained by setting the adhesive film thickness to 5 μm or more. Moreover, by setting it to 200 μm or less, it becomes easier to control the amount of residual solvent in the drying process, and it becomes difficult for expansion to occur during pressing in the manufacture of printed wiring boards. Drying conditions are not particularly limited, but the residual solvent content after drying is preferably 1% by mass or less. By setting it to 1% by mass or less, foaming of the residual solvent during printing of the printed wiring board is suppressed, and expansion becomes difficult to occur.

<Printed wiring board>

The printed wiring board in the present invention includes a laminate formed of metal foil and a resin substrate forming a conductor circuit as constituent elements, and examples include flexible substrates, rigid substrates, and package substrates. Printed wiring boards are manufactured, for example, by conventionally known methods such as the subtractive method using a metal-clad laminate. If necessary, a conductor circuit formed of metal foil is partially or completely covered with a cover film or screen printing ink, so-called flexible circuit boards (FPC), flat cables, circuit boards for tape automated bonding (TAB), etc. It is collectively referred to as .

The printed wiring board of the present invention can have any laminated configuration that can be employed as a printed wiring board. For example, it can be a printed wiring board composed of four layers: a base film layer, a metal foil layer, an adhesive layer, and a cover film layer. Additionally, for example, it can be used as a printed wiring board composed of five layers: a base film layer, an adhesive layer, a metal foil layer, an adhesive layer, and a cover film layer.

Additionally, if necessary, the printed wiring board may be stacked in two or three or more pieces.

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 adhesion not only to conventional polyimide, polyester film, and copper foil that constitute printed wiring boards, but also to low-polar resin substrates such as LCP, and is resistant to solder reflow. Dominance can be achieved, and the adhesive layer itself has excellent low dielectric properties. Therefore, it is suitable as an adhesive composition used for coverlay films, laminated boards, copper foil with resin, and bonding sheets.

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

<Cover Film>

As the cover film, any conventionally known insulating film as an insulating film for a printed wiring board can be used. For example, various polymers such as polyimide, polyester, polyphenylene sulfide, polyether sulfone, polyether ether ketone, aramid, polycarbonate, polyarylate, polyamidoimide, liquid crystal polymer, syndiotactic polystyrene, and polyolefin resin. Films manufactured with can be used. 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 materials for 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 manufactured. On the other hand, a semi-finished product in which a metal foil layer is laminated on a base film layer and a desired circuit pattern is formed (hereinafter referred to as “base 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 on it. A semi-finished product with a desired circuit pattern (hereinafter referred to as “base film side 3-layer semi-finished product”) is manufactured (hereinafter referred to as “base film-side 3-layer semi-finished product” by combining the base film-side 2-layer semi-finished product and the base film-side 3-layer semi-finished product). called). By joining the semi-finished product on the cover film side and the semi-finished product on the base film side obtained in this way, a four- or five-layer printed wiring board can be obtained.

The semi-finished product on the base film side includes, for example, (A) applying a solution of a resin that becomes the base film to the metal foil and initially drying the coating film; (B) heat treating the laminate of the metal foil and the initially dried coating film obtained in (A); · Obtained by a manufacturing method that includes a drying process (hereinafter referred to as “heat treatment/solvent removal process”).

For forming the circuit in the metal foil layer, a conventionally known method can be used. The additive method may be used, or the subtractive method may be used. Preferably, it is a subtractive method.

The obtained base film side semi-finished product may be used as 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 semi-finished product on the cover film side is manufactured, for example, by applying an adhesive to the cover film. 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 is for bonding with the base film side semi-finished product, or may be used for bonding with the base film side semi-finished product after bonding and storing a release film.

The semi-finished products on the base film side and the semi-finished products on the cover film side are each stored in, for example, the form of a roll and then joined to produce a printed wiring board. As a joining method, any method can be used, for example, joining can be done using a press or roll. Additionally, the two can also be joined while being heated by a method such as using a heating press or a heating roll device.

For example, in the case of a reinforcing material that is flexible and can be wound, such as a polyimide film, the semi-finished product on the reinforcing material side is suitably manufactured by applying an adhesive to the reinforcing material. Additionally, in the case of reinforcing plates that are too hard and cannot be wound, such as metal plates such as SUS or aluminum, or plates made of glass fibers cured with epoxy resin, it is suitable to be manufactured by transferring and applying an adhesive previously applied to a release substrate. Additionally, if necessary, a crosslinking reaction in the applied adhesive can be performed. In a preferred embodiment, the adhesive layer is semi-cured.

The obtained reinforcing material side semi-finished product may be used as is for bonding with the back side of the printed wiring board, or may be used for bonding with the base film side semi-finished product after bonding and storing a release film.

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

Example

Hereinafter, the present invention will be described in detail through examples. In addition, in the present Examples and Comparative Examples, simply part refers to the mass part.

<Method for evaluating physical properties>

(Measurement of composition of polyester resin)

Using a 400 MHz ^1H -nuclear magnetic resonance spectrum device (hereinafter sometimes abbreviated as NMR), the molar ratio of the polyhydric carboxylic acid component and polyhydric alcohol component that constitutes the polyester resin was quantified. Deuterated chloroform was used as the solvent. In addition, when the acid value of the copolyester was raised by post-acid addition, the total amount of acidic components other than the acidic component used in post-acid addition was set to 100 mol%, and the molar ratio of each component was calculated.

(Measurement of glass transition temperature)

It was measured using a differential scanning calorimeter (SII, DSC-200). 5 mg of the sample was placed in an aluminum push lid container, sealed, and cooled to -50°C using liquid nitrogen. Subsequently, the temperature is raised to 150°C at a temperature increase rate of 20°C/min, and in the endothermic curve obtained during the temperature increase, an extension of the baseline before the endothermic peak appears (below the glass transition temperature) and a tangent line (peak) toward the endothermic peak. The temperature at the intersection of the tangent line representing the maximum slope from the rising portion of to the peak peak was taken as the glass transition temperature (unit: °C).

(Measurement of 5% weight loss temperature)

Measurements were made using a simultaneous differential heat and thermogravimetric measurement device (DTG-60, Shimazu Seisakusho Co., Ltd.). A 5 mg sample placed in an aluminum pan was heated at a temperature increase rate of 10°C/min in an air atmosphere, and the temperature at which 5% of the weight was lost due to thermal decomposition was defined as the 5% weight loss temperature (unit:°C). did.

(Measurement of acid value)

A 0.2 g sample of polyester resin was dissolved in 40 ml of chloroform and titrated with a 0.01 N potassium hydroxide ethanol solution to determine the equivalent weight per 10 ⁶ g of polyester resin (equivalent weight/10 ⁶ g). Phenolphthalein was used as an indicator.

(relative permittivity (ε _c ) and dielectric loss tangent (tanδ))

The polyester resin dissolved in a solvent was applied to a 100 ㎛ thick Teflon (registered trademark) sheet so that the thickness after drying was 25 ㎛, dried at 130°C for 3 minutes, and then the Teflon (registered trademark) sheet was peeled off to form a test resin. Got the sheet. After that, the obtained test resin sheet was cut into strips of 8 cm x 3 mm to obtain a test sample. The relative dielectric constant (ε _c ) and dielectric loss tangent (tanδ) were measured by the cavity resonator perturbation method using a network analyzer (manufactured by Anritsu Corporation) under the conditions of a temperature of 23°C and a frequency of 10 GHz.

Hereinafter, examples of synthesis of the polyester resin used in the present invention are shown.

Synthesis example of polyester resin (c1)

In a reaction vessel equipped with a stirrer, condenser, and thermometer, 275 parts of dimethyl naphthalenedicarboxylate, 5 parts of trimellitic anhydride, 264 parts of dimer diol, 125 parts of tricyclodecane dimethanol, 76 parts of ethylene glycol, and tetra orthotitanic acid as a catalyst. Butyl was injected in an amount of 0.03 mol% based on the total acid components, and an esterification reaction was performed by heating and dehydrating from 160°C to 220°C over 4 hours. Next, in the polycondensation reaction step, the pressure inside the system was reduced to 5 mmHg over 20 minutes, and the temperature was further raised to 250°C. Subsequently, the pressure was reduced to 0.3 mmHg or less, and a polycondensation reaction was performed for 60 minutes, followed by extraction. As a result of composition analysis by NMR, the obtained polyester resin (c1) was found to have a molar ratio of naphthalene dicarboxylic acid/trimellitic anhydride/dimer diol/tricyclodecane dimethanol/ethylene glycol = 97/3/40/55/5. It was a copolymer of polyester. Additionally, the glass transition temperature was 17°C, the acid value was 3 equivalents/10 ⁶ g, and the dielectric loss tangent at 10 GHz was 0.0035.

Synthesis example of polyester resin (c2)

In a reaction vessel equipped with a stirrer, condenser, and thermometer, 348 parts of terephthalic acid, 311 parts of isophthalic acid, 99 parts of sebacic acid, 228 parts of ethylene glycol, 313 parts of neopentyl glycol, and 0.03 mol of tetrabutyl orthotitanate as a catalyst based on the total acid content. % was injected, and an esterification reaction was performed by heating and dehydrating from 160°C to 220°C over 4 hours. Next, in the polycondensation reaction step, the pressure inside the system was reduced to 5 mmHg over 20 minutes, and the temperature was further raised to 250°C. Subsequently, the pressure was reduced to 0.3 mmHg or less, and a polycondensation reaction was performed for 60 minutes, followed by extraction. As a result of composition analysis by NMR, the obtained polyester resin (c2) was a copolyester with a molar ratio of terephthalic acid/isophthalic acid/sebacic acid/ethylene glycol/neopentyl glycol = 47/42/11/55/45. Additionally, the glass transition temperature was 47°C, the acid value was 3 equivalents/10 ⁶ g, and the dielectric loss tangent at 10 GHz was 0.0076.

Hereinafter, manufacturing examples of adhesive compositions serving as examples of the present invention and adhesive compositions serving as comparative examples are shown.

As compound A, the following was used.

(a1): SA-9000 (manufactured by SABIC, polyphenylene ether with a vinyl group, number average molecular weight 1700, 5% weight loss temperature 439°C)

(a2): FTC809AE (manufactured by Gunei Chemical Co., Ltd., phenolic resin having a vinyl group, number average molecular weight 1400, 5% weight loss temperature 332°C)

(a3): PEGDA (manufactured by Sigma-Aldrich, polyethylene glycol diacrylate, weight average molecular weight 700, 5% weight loss temperature 220°C)

(a4): SA-90 (manufactured by SABIC, polyphenylene ether having a hydroxyl group terminal (no terminal unsaturated hydrocarbon group), number average molecular weight 1700, 5% weight loss temperature 430°C)

As compound B, the following was used.

(b1): DA-MGIC (manufactured by Shikoku Chemical Industry Co., Ltd., diallyl monoglycidyl isocyanurate)

(b2): MA-DGIC (manufactured by Shikoku Chemical Industry Co., Ltd., monoallyl diglycidyl isocyanurate)

(b3): Diallyl isocyanurate (manufactured by Tokyo Kasei Kogyo)

In addition to the above, the following were used.

V-03: Polycarbodiimide (manufactured by Nisshinbo Chemical Co., Ltd.)

Tetrad

Perbutyl P: Radical generator (manufactured by Nichi Yu Co., Ltd., bis(1-t-butylperoxy-1-methylethyl)benzene, half-life temperature 175°C for 1 minute)

<Example 1>

The polyester resin (c1) obtained in the above synthesis example was dissolved in toluene to prepare a toluene varnish with a solid content concentration of 40% by mass. To this toluene varnish, (a1) as compound A, (b1) as compound B, and perbutyl P were mixed in an amount of 20 parts, 5 parts, and 3 parts, respectively, based on 100 parts of polyester resin (c1), to obtain an adhesive composition ( S1) was obtained.

The obtained adhesive composition (S1) was evaluated for relative dielectric constant, dielectric loss tangent, peeling strength, solder heat resistance, and adhesive sheet flexibility. The results are listed in Table 1.

<Examples 2 to 14, Comparative Examples 1 to 5>

Adhesive compositions (S2) to (S19) were prepared in the same manner as in Example 1 except that the types and mixing amounts of each component of the adhesive composition were changed as shown in Table 1, and each evaluation was performed. The results are listed in Table 1.

<Evaluation of adhesive composition>

(relative permittivity (ε _c ) and dielectric loss tangent (tanδ))

The adhesive composition was applied to a 100 ㎛ thick Teflon (registered trademark) sheet so that the thickness after drying was 25 ㎛, and dried at 130°C for 3 minutes. After curing by subsequent heat treatment at 180°C for 5 hours, the Teflon (registered trademark) sheet was peeled off to obtain an adhesive resin sheet for testing. After that, the obtained test adhesive resin sheet was cut into strips of 8 cm x 3 mm to obtain a test sample. The relative dielectric constant (ε _c ) and dielectric loss tangent (tanδ) were measured by the cavity resonator perturbation method using a network analyzer (manufactured by Anritsu Corporation) under the conditions of a temperature of 23°C and a frequency of 10 GHz.

<Evaluation criteria for relative permittivity>

○: 3.0 or less

×: exceeds 3.0

<Evaluation criteria for dielectric loss tangent>

○: Less than 0.004

△: 0.004 or more and 0.006 or less

×: exceeds 0.006

(Peel strength (adhesiveness))

The adhesive composition was applied to a 12.5 ㎛ thick polyimide film (Apical (registered trademark) manufactured by Kaneka Co., Ltd.) so that the thickness after drying was 25 ㎛, and dried at 130°C for 3 minutes. The adhesive film (B stage product) thus obtained was bonded to rolled copper foil (Nittetsu Chemical & Material Co., Ltd., Espanex series) with a thickness of 18 µm. For bonding, the glossy surface of the rolled copper foil was brought into contact with the adhesive layer, and the adhesive was pressed at 170°C for 280 seconds under a pressure of 2 MPa. Subsequently, it was cured by heat treatment at 180°C for 3 hours to obtain a sample for peeling strength evaluation. Peel strength was measured under the conditions of 25°C, film pulling, tensile speed of 50 mm/min, and 90° peeling. This test indicates adhesive strength at room temperature.

<Evaluation criteria>

◎: 1.0 N/㎜ or more

○: 0.7 N/mm or more but less than 1.0 N/mm

△: 0.5 N/mm or more but less than 0.7 N/mm

×: Less than 0.5 N/mm

(Solder heat resistance)

A sample for evaluation was produced in the same manner as for measuring the peeling strength, and a sample piece of 2.0 cm

<Evaluation criteria>

◎: No expansion for more than 60 seconds

○: There is swelling for more than 30 seconds and less than 60 seconds.

△: Swelling occurs for more than 10 seconds and less than 30 seconds.

×: Expansion occurs in less than 10 seconds

(adhesive sheet flexibility)

The adhesive composition is applied to a 100 ㎛ thick Teflon (registered trademark) sheet so that the thickness after drying is 25 ㎛, and dried at 130°C for 3 minutes. Next, the state of the coating film when the sheet was bent 180° was confirmed.

<Evaluation criteria>

○: No cracks

×: With cracks

As is clear from Table 1, Examples 1 to 14 are excellent in dielectric properties, peel strength, solder heat resistance, and adhesive sheet flexibility. On the other hand, in Comparative Example 1, because compound B did not have an epoxy group, curing was insufficient and solder heat resistance was insufficient. In Comparative Example 2, because Compound A did not have terminal unsaturated hydrocarbons, curing was insufficient and solder heat resistance was insufficient. Additionally, the dielectric loss tangent was high due to the influence of the hydroxyl group terminal. In Comparative Example 3, the 5% weight loss temperature of Compound A was low, so the solder heat resistance was inferior. Since Comparative Example 4 did not contain polyester resin, the adhesive sheet was weak and had poor dielectric properties, peel strength, and solder heat resistance. Comparative Example 5 did not contain compound B and was cured with an epoxy resin, so its dielectric properties were inferior.

The adhesive composition of the present invention is excellent in heat resistance and adhesive strength, has low relative dielectric constant and dielectric loss tangent, and also has good sheet flexibility. Therefore, it is useful as an adhesive or adhesive sheet for printed wiring boards applied to printed boards (flexible boards, rigid boards, package boards) in the high frequency range.

Claims (9)

An adhesive composition comprising a polyester resin, compound A, and compound B.
Compound A: A compound having a terminal unsaturated hydrocarbon group and a 5% weight loss temperature of 260°C or higher.
Compound B: Compound having an epoxy group and a terminal unsaturated hydrocarbon group The adhesive composition according to claim 1, wherein the compound A is a compound having an aromatic ring structure or an alicyclic structure as a structural unit. The adhesive composition according to claim 1, wherein the compound A is a polyphenylene ether or a phenol resin having a terminal unsaturated hydrocarbon group. The adhesive composition according to any one of claims 1 to 3, wherein the compound B is a compound having an isocyanuric ring. The adhesive composition according to any one of claims 1 to 4, wherein the polyester resin has a dielectric loss tangent of 0.005 or less. The adhesive composition according to any one of claims 1 to 5, further comprising polycarbodiimide. An adhesive sheet having an adhesive layer containing the adhesive composition according to any one of claims 1 to 6. A laminate having an adhesive layer containing the adhesive composition according to any one of claims 1 to 6. A printed wiring board comprising the laminate according to claim 8 as a component.