WO2021205675A1 - Bismaleimide-based adhesive composition, cured product, adhesive sheet, and flexible printed wiring board - Google Patents

Abstract

This bismaleimide-based adhesive composition contains: an inorganic filler (B); and a bismaleimide resin (A) formed by reacting an aromatic tetracarboxylic acid (a1), a dimer diamine (a2), and a maleic anhydride (a3), wherein the content of the inorganic filler (B) is 5-55 mass% with respect to the total solid content of the adhesive composition.

Description

Bismaleimide-based adhesive composition, cured product, adhesive sheet and flexible printed wiring board

The present invention relates to a bismaleimide-based adhesive composition, a cured product, an adhesive sheet, and a flexible printed wiring board. More specifically, the present invention relates to a novel bismaleimide-based adhesive composition having excellent low-dielectric properties and further having high adhesiveness to a base material such as a copper foil and a polyimide sheet.

Flexible printed wiring boards (hereinafter abbreviated as "FPC") and multi-layer wiring boards using FPC are mobile communication devices such as mobile phones and smartphones, their base station devices, network-related electronic devices such as servers and routers, and large-sized ones. Used in products such as computers.

In recent years, high-frequency electrical signals have been used in these products to transmit and process large amounts of information at high speed, but high-frequency signals are extremely easily attenuated, so they are used in the above FPCs, multilayer wiring boards, etc. However, it is necessary to devise ways to suppress transmission loss.

Transmission loss can be distinguished into "dielectric loss" derived from the dielectric, that is, the insulating material around the conductor (copper circuit), and "conductor loss" derived from the copper circuit itself, and it is necessary to suppress both.

The dielectric loss depends on the frequency and the dielectric constant and dielectric loss tangent of the insulating material around the copper circuit. As the frequency increases, it is necessary to use a material having a low dielectric constant and a low dielectric loss tangent as the insulating material.

On the other hand, the conductor loss is caused by the skin effect, that is, the phenomenon that the AC current density on the surface of the copper circuit increases and its resistance increases, and becomes remarkable when the frequency exceeds 1 GHz. The main measure to suppress conductor loss is to smooth the surface of the copper circuit.

In order to suppress the dielectric loss, as described above, it is preferable to use a material having a low dielectric constant and a low dielectric loss as the insulating material, and as such a material, a specific polyimide has been conventionally used ( (See Patent Documents 1 and 2).

JP-A-2009-299040 Japanese Unexamined Patent Publication No. 2014-045076

However, since the above-mentioned insulating material does not have a polar group, that is, a functional group such as a hydroxyl group, a carboxyl group, and a nitrile group, or even if it has a small amount, there is a problem that it is difficult to adhere to a smooth copper circuit. be. On the contrary, a material having many such functional groups tends to have a high dielectric constant and a high dielectric loss tangent even though the adhesion to a smooth copper circuit is high.

Therefore, the present invention has low dielectric constant and dielectric loss tangent (hereinafter, both may be collectively referred to as "dielectric properties"), and has good adhesion to copper and polyimide films, particularly copper having a smooth surface. The main task is to provide a novel bismaleimide-based adhesive.

That is, an object of the present invention is to provide a bismaleimide-based adhesive composition having low dielectric properties and excellent adhesiveness to a base material such as a copper foil and a polyimide sheet. Another object of the present invention is to provide a cured product, an adhesive sheet, and a flexible printed wiring board using the above-mentioned bismaleimide-based adhesive composition.

As a result of diligent studies to solve the above problems, the present inventors have made a bismaleimide resin (A) obtained by reacting aromatic tetracarboxylic acids (a1), dimer diamine (a2), and maleic anhydride (a3). ) And the inorganic filler (B), and the content of the inorganic filler (B) is within a predetermined range. We have found that it has high adhesiveness to a base material such as a copper foil and a polyimide sheet, and have completed the present invention.

［式（１）中、Ｘは単結合又は下記群より選ばれる少なくとも一種の基を表す。］

［３］上記ダイマージアミン（ａ２）が、下記一般式（２）及び／又は一般式（２’）で表される化合物である、上記［１］又は［２］に記載のビスマレイミド系接着剤組成物。

［式（２）及び（２’）中、ｍ、ｎ、ｐ及びｑはそれぞれ、ｍ＋ｎ＝６～１７、ｐ＋ｑ＝８～１９となるように選ばれる１以上の整数を表し、破線で示した結合は、炭素－炭素単結合又は炭素－炭素二重結合を意味する。但し、破線で示した結合が炭素－炭素二重結合である場合、式（２）及び（２’）は、炭素－炭素二重結合を構成する各炭素原子に結合する水素原子の数を、式（２）及び（２’）に示した数から１つ減じた構造となる。］
［４］上記ビスマレイミド樹脂（Ａ）の重量平均分子量が３０００～２５０００である、上記［１］～［３］のいずれかに記載のビスマレイミド系接着剤組成物。
［５］上記無機充填材がシリカである、上記［１］～［４］のいずれかに記載のビスマレイミド系接着剤組成物。
［６］更に重合開始剤（Ｄ）を含む、上記［１］～［５］のいずれかに記載のビスマレイミド系接着剤組成物。
［７］上記重合開始剤（Ｄ）が、有機過酸化物、イミダゾール化合物、ホスフィン化合物、ホスホニウム塩化合物からなる群より選ばれる少なくとも１種である、上記［６］に記載のビスマレイミド系接着剤組成物。
［８］上記無機充填材（Ｂ）の平均粒径が１００ｎｍ～１０μｍである、上記［１］～［７］のいずれかに記載のビスマレイミド系接着剤組成物。
［９］上記無機充填材（Ｂ）の平均粒径が２００ｎｍ～１．０μｍである、上記［１］～［８］のいずれかに記載のビスマレイミド系接着剤組成物。
［１０］上記無機充填材（Ｂ）の含有量が、接着剤組成物の固形分全量を基準として５～２５質量％である、上記［１］～［９］のいずれかに記載のビスマレイミド系接着剤組成物。
［１１］上記［１］～［１０］のいずれかに記載のビスマレイミド系接着剤組成物を硬化させることにより得られる硬化物。
［１２］上記［１］～［１０］のいずれかに記載のビスマレイミド系接着剤組成物をシート基材に塗布し、乾燥させることによって得られる接着シート。
［１３］上記［１２］に記載の接着シートの接着面に更にシート基材を熱圧着させることにより得られる積層体。
［１４］上記［１３］に記載の積層体を更に加熱することによって得られる積層体。
［１５］上記［１４］に記載の積層体を用いてなるフレキシブルプリント配線板。 That is, the present invention provides the following inventions.
[1] The above-mentioned inorganic containing a bismaleimide resin (A) obtained by reacting aromatic tetracarboxylic acids (a1), dimerdiamine (a2), and maleic anhydride (a3) and an inorganic filler (B). A bismaleimide-based adhesive composition in which the content of the filler (B) is 5 to 55% by mass based on the total solid content of the adhesive composition.
[2] The bismaleimide-based adhesive composition according to the above [1], wherein the aromatic tetracarboxylic acid (a1) is pyromellitic anhydride or a compound represented by the following general formula (1).

[In formula (1), X represents a single bond or at least one group selected from the following groups. ]

[3] The bismaleimide-based adhesive according to the above [1] or [2], wherein the diamine diamine (a2) is a compound represented by the following general formula (2) and / or the general formula (2'). Composition.

[In equations (2) and (2'), m, n, p and q represent integers of 1 or more selected so that m + n = 6 to 17 and p + q = 8 to 19, respectively, and are shown by broken lines. The bond means a carbon-carbon single bond or a carbon-carbon double bond. However, when the bond shown by the broken line is a carbon-carbon double bond, the formulas (2) and (2') indicate the number of hydrogen atoms bonded to each carbon atom constituting the carbon-carbon double bond. The structure is obtained by subtracting one from the numbers shown in the formulas (2) and (2'). ]
[4] The bismaleimide-based adhesive composition according to any one of the above [1] to [3], wherein the weight average molecular weight of the bismaleimide resin (A) is 3000 to 25000.
[5] The bismaleimide-based adhesive composition according to any one of the above [1] to [4], wherein the inorganic filler is silica.
[6] The bismaleimide-based adhesive composition according to any one of the above [1] to [5], further comprising a polymerization initiator (D).
[7] The bismaleimide-based adhesive according to the above [6], wherein the polymerization initiator (D) is at least one selected from the group consisting of an organic peroxide, an imidazole compound, a phosphine compound, and a phosphonium salt compound. Composition.
[8] The bismaleimide-based adhesive composition according to any one of the above [1] to [7], wherein the inorganic filler (B) has an average particle size of 100 nm to 10 μm.
[9] The bismaleimide-based adhesive composition according to any one of the above [1] to [8], wherein the inorganic filler (B) has an average particle size of 200 nm to 1.0 μm.
[10] The bismaleimide according to any one of the above [1] to [9], wherein the content of the inorganic filler (B) is 5 to 25% by mass based on the total solid content of the adhesive composition. Adhesive composition.
[11] A cured product obtained by curing the bismaleimide-based adhesive composition according to any one of the above [1] to [10].
[12] An adhesive sheet obtained by applying the bismaleimide-based adhesive composition according to any one of the above [1] to [10] to a sheet substrate and drying it.
[13] A laminate obtained by further thermocompression-bonding a sheet base material to the adhesive surface of the adhesive sheet according to the above [12].
[14] A laminate obtained by further heating the laminate according to the above [13].
[15] A flexible printed wiring board using the laminate according to the above [14].

According to the present invention, a bismaleimide-based adhesive composition having low dielectric properties and excellent adhesiveness to a base material such as a copper foil and a polyimide sheet, a cured product using the same, an adhesive sheet, and the like. Flexible printed wiring boards can be provided.

The adhesive composition of the present invention is excellent not only in low dielectric properties in the high frequency band but also in adhesiveness to substrates such as copper foil and polyimide sheet. Further, the cured product (adhesive layer) obtained from the adhesive composition has a low tack, a high 5% weight loss temperature, a small amount of outgas, and a low linear expansion coefficient (CTE), so that it is a printed circuit board. Not only as an adhesive used for manufacturing (build-up boards, flexible printed wiring boards, etc.) and copper-clad boards for flexible printed wiring boards, but also as electrical insulating materials such as semiconductor interlayer materials, coating agents, resist inks, and conductive pastes. Is also useful.

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

<Bismaleimide-based adhesive composition>
The bismaleimide-based adhesive composition of the present embodiment includes aromatic tetracarboxylic acids (a1) (hereinafter, also referred to as “(a1) component”) and dimerdiamine (a2) (hereinafter, also referred to as “(a2) component”). The bismaleimide resin (A) (hereinafter, also referred to as "(A) component") obtained by reacting maleic anhydride (a3) (hereinafter, also referred to as "(a3) component"). Includes an inorganic filler (B) (hereinafter, also referred to as “component (B)”). The bismaleimide-based adhesive composition of the present embodiment may further contain an organic solvent (C) (hereinafter, also referred to as “component (C)”). Further, the bismaleimide-based adhesive composition of the present embodiment may further contain a polymerization initiator (D) (hereinafter, also referred to as “component (D)”).

(Component (A): Bismaleimide resin)
The component (A) can be obtained by reacting the component (a1), the component (a2), and the component (a3).

［式（１）中、Ｘは単結合又は下記群より選ばれる少なくとも一種の基を表す。］

As the component (a1), a material known as a raw material for polyimide can be used. Specific examples thereof include pyromellitic anhydride and a compound represented by the following general formula (1).

[In formula (1), X represents a single bond or at least one group selected from the following groups. ]

Examples of the compound represented by the formula (1) include 4,4'-oxydiphthalic acid dianhydride, 3,3', 4,4'-diphenyl ether tetracarboxylic acid dianhydride, 3,3', 4, 4'-Diphenylsulfone tetracarboxylic acid dianhydride, 3,3', 4,4'-biphenyltetracarboxylic acid dianhydride, 2,2', 3,3'-biphenyltetracarboxylic acid dianhydride, 2, 3,3', 4'-biphenyltetracarboxylic acid dianhydride, 2,3,3', 4'-diphenyl ether tetracarboxylic acid dianhydride, 2,3,3', 4'-diphenylsulfone tetracarboxylic acid dianhydride Anhydride, 2,2-bis (3,3', 4,4'-tetracarboxyphenyl) tetrafluoropropane dianhydride, 2,2'-bis (3,4-dicarboxyphenoxyphenyl) sulfone dianhydride , 2,2-bis (2,3-dicarboxyphenyl) propane dianhydride, 2,2-bis (3,4-dicarboxyphenyl) propane dianhydride, butane-1,2,3,4-tetra Carboxylate, 2,3,5-tricarboxycyclopentylacetic anhydride, 4,4'-[Propane-2,2-diylbis (1,4-phenyleneoxy)] diphthalate dianhydride, 4,4'-(hexa) Fluoroisopropylidene) Diphthalic anhydride and the like can be mentioned. These can be used alone or in combination of two or more.

The component (a2) is, for example, a compound derived from dimer acid, which is a dimer of unsaturated fatty acids such as oleic acid, as described in Japanese Patent Application Laid-Open No. 9-12712. In the present embodiment, known diamine diamines can be used without particular limitation, but those represented by the following general formulas (2) and / or general formulas (2') are preferable.

［式（２）及び（２’）中、ｍ、ｎ、ｐ及びｑはそれぞれ、ｍ＋ｎ＝６～１７、ｐ＋ｑ＝８～１９となるように選ばれる１以上の整数を表し、破線で示した結合は、炭素－炭素単結合又は炭素－炭素二重結合を意味する。但し、破線で示した結合が炭素－炭素二重結合である場合、式（２）及び（２’）は、炭素－炭素二重結合を構成する各炭素原子に結合する水素原子の数を、式（２）及び（２’）に示した数から１つ減じた構造となる。］

[In equations (2) and (2'), m, n, p and q represent integers of 1 or more selected so that m + n = 6 to 17 and p + q = 8 to 19, respectively, and are shown by broken lines. The bond means a carbon-carbon single bond or a carbon-carbon double bond. However, when the bond shown by the broken line is a carbon-carbon double bond, the formulas (2) and (2') indicate the number of hydrogen atoms bonded to each carbon atom constituting the carbon-carbon double bond. The structure is obtained by subtracting one from the numbers shown in the formulas (2) and (2'). ]

The diamine diamine is preferably represented by the above general formula (2'), particularly represented by the following formula (3), from the viewpoints of solubility in an organic solvent, heat resistance, heat resistance adhesiveness, low viscosity and the like. Compounds are preferred.

Examples of commercially available diamine diamines include PRIAMINE 1075 and PRIAMINE 1074 (both manufactured by Croda Japan Co., Ltd.). These can be used alone or in combination of two or more.

The component (A) can be produced by various known methods. For example, first, the component (a1) and the component (a2) are mixed at a temperature of about 60 to 120 ° C., preferably 70 to 90 ° C., usually about 0.1 to 2 hours, preferably 0.1 to 1.0 hour. The double addition reaction is carried out. Then, the obtained heavy adduct is further imidized at a temperature of about 80 to 250 ° C., preferably 100 to 200 ° C. for about 0.5 to 30 hours, preferably 0.5 to 10 hours, that is, a dehydration ring closure reaction. Let me. Subsequently, the product subjected to the dehydration ring closure reaction and the component (a3) are maleimided at a temperature of about 60 to 250 ° C., preferably 80 to 200 ° C. for about 0.5 to 30 hours, preferably 0.5 to 10 hours. By the reaction, that is, the dehydration ring closure reaction, the desired component (A) is obtained.

In the imidization reaction or maleimidization reaction, various known reaction catalysts, dehydrating agents, and organic solvents described later can be used. Examples of the reaction catalyst include aliphatic tertiary amines such as triethylamine, aromatic tertiary amines such as dimethylaniline, heterocyclic tertiary amines such as pyridine, picolin and isoquinolin, or methanesulfonic acid and para. Examples thereof include organic acids such as toluene sulfonic acid monohydrate. These can be used alone or in combination of two or more. Examples of the dehydrating agent include aliphatic acid anhydrides such as acetic anhydride and aromatic acid anhydrides such as benzoic anhydride. These can be used alone or in combination of two or more.

In addition, the component (A) can be purified by various known methods to increase the purity. For example, first, the component (A) dissolved in an organic solvent and pure water are put into a separating funnel. Then, the separatory funnel is shaken and allowed to stand. Subsequently, after the aqueous layer and the organic layer are separated, the component (A) can be purified by recovering only the organic layer.

The molecular weight of the component (A) can be controlled by the number of moles of the component (a1) and the component (a2), and the molecular weight is reduced as the number of moles of the component (a1) is smaller than the number of moles of the component (a2). be able to. For the purpose of facilitating the achievement of the effects of the present invention, [the number of moles of the component (a1)] / [the number of moles of the component (a2)] is usually about 0.30 to 0.85, preferably 0.50 to 0. A range of .80 is good.

As the molecular weight of the component (A), the weight average molecular weight is preferably 3000 to 25000, more preferably 7000 to 20000, from the viewpoint of solubility in a solvent and heat resistance. When the weight average molecular weight is 25,000 or less, the solubility in an organic solvent is good, and when it is 3000 or more, the effect of improving heat resistance tends to be sufficiently obtained.

As the component (A) of the present embodiment, a commercially available compound can be used. Specifically, for example, DESIGNER MOLECURES Inc. BMI-3000CG (synthesized from dimer diamine, pyromellitic anhydride and maleic anhydride), BMI-1500, BMI-1700, BMI-5000 and the like can be preferably used. The component (A) can be used alone or in combination of two or more.

(Component (B): Inorganic filler)
As the component (B), various known inorganic fillers can be used without particular limitation as long as they are inorganic fillers that can be used in the bismaleimide-based adhesive composition. Examples of the component (B) include aluminum hydroxide, magnesium hydroxide, calcium carbonate, magnesium carbonate, calcium silicate, magnesium silicate, calcium oxide, magnesium oxide, aluminum oxide, aluminum nitride, aluminum borate whisker, and boron nitride. , Silica, graphite powder, boehmite and the like. Of these, silica is particularly preferable because it has excellent low dielectric loss tangent. The component (B) can be used alone or in combination of two or more.

The average particle size of the component (B) may be 50 nm or more, 100 nm or more, or 200 nm or more, and may be 10 μm or less, 5.0 μm or less, 3.0 μm or less, or 1.0 μm or less. The average particle size of the component (B) is preferably 100 nm to 10 μm, or 50 nm to 5.0 μm, more preferably 100 nm to 3.0 μm, and even more preferably 200 nm to 1.0 μm. When the average particle size of the component (B) is in the above range, the surface roughness of the adhesive sheet can be reduced and the adhesiveness to the base material such as the polyimide film and the copper foil can be improved.

As the average particle size of the component (B), the value of the median diameter (d50), which is 50% of the integrated particle size in the volume integrated particle size distribution, is adopted. The average particle size can be measured using a laser diffraction / scattering type particle size distribution measuring device.

The component (B) is preferably surface-treated, preferably a surface-treated product with a coupling agent, and more preferably a surface-treated product with a silane coupling agent. By surface-treating the component (B), not only the dispersibility of the component (B) in the organic solvent can be enhanced, but also the surface roughness of the surface of the adhesive sheet becomes smaller, and the polyimide film And the adhesiveness with a base material such as copper foil can be enhanced.

Examples of the coupling agent include a silane coupling agent, a titanium coupling agent, an aluminum coupling agent, and the like. Examples of the silane coupling agent include methacrylsilane, acrylicsilane, aminosilane, phenylaminosilane, imidazolesilane, phenylsilane, vinylsilane, and epoxysilane. These can be used alone or in combination of two or more.

The content of the component (B) is 5 to 55% by mass, preferably 5 to 50% by mass, based on the total solid content (nonvolatile content) of the adhesive composition (100% by mass). It is more preferably to 25% by mass, or 10 to 35% by mass. When the content of the component (B) is 55% by mass or less, the decrease in adhesiveness tends to be suppressed, and when it is 5% by mass or more, the effect of reducing dielectric loss tangent and the effect of improving heat resistance Tends to be sufficiently obtained.

(Component (C): organic solvent)
The component (C) is not particularly limited as long as it dissolves the component (A). Examples of the component (C) include aromatic hydrocarbons such as benzene, toluene, xylene, and mesityrene, alcohol solvents such as methanol, ethanol, isopropyl alcohol, butanol, pentanol, hexanol, propanediol, and phenol, acetone, and methyl. Ketone solvents such as isobutyl ketone, methyl ethyl ketone, pentanon, hexanone, cyclopentanone, cyclohexanone, isophorone, and acetophenone, cell solves such as methyl cellsolve and ethyl cell solve, methyl acetate, ethyl acetate, butyl acetate, methyl propionate, formic acid. Ester solvent such as butyl, 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-iso-butyl ether, triethylene glycol mono- Glycol ether-based solvents such as n-butyl ether and tetraethylene glycol mono-n-butylate can be used. These can be used alone or in combination of two or more. As a preferred embodiment, it is preferable to use a combination of toluene or mesitylene, which is an aromatic hydrocarbon having high solubility of the component (A), and methyl ethyl ketone or methyl isobutyl ketone, which is a ketone solvent having high dispersibility of the component (B). ..

The amount of the component (C) used is not particularly limited, but usually, it may be used in a range in which the non-volatile content of the adhesive composition of the present embodiment is about 20 to 65% by mass.

(Component (D): Polymerization initiator)
Specific examples of the component (D) include organic peroxides, imidazole compounds, phosphine compounds, and phosphonium salt compounds. These can be used alone or in combination of two or more. Of these, the imidazole compound is particularly preferable because it has an excellent function as a polymerization initiator and is also excellent in terms of low dielectric properties.

Examples of the organic peroxide include methyl ethyl ketone peroxide, methyl cyclohexanone peroxide, methyl acetoacetate peroxide, acetyl acetone peroxide, 1,1-bis (t-butyl peroxy) 3,3,5-trimethylcyclohexane, and 1 , 1-bis (t-hexyl peroxy) cyclohexane, 1,1-bis (t-hexyl peroxy) 3,3,5-trimethylcyclohexane, 1,1-bis (t-butylperoxy) cyclohexane, 2, 2-Bis (4,5-di-t-butylperoxycyclohexyl) propane, 1,1-bis (t-butylperoxy) cyclododecane, n-butyl 4,4-bis (t-butylperoxy) valerate , 2,2-bis (t-butylperoxy) butane, 1,1-bis (t-butylperoxy) -2-methylcyclohexane, t-butylhydroperoxide, P-menthanhydroperoxide, 1,1 , 3,3-Tetramethylbutylhydroperoxide, t-hexylhydroperoxide, dicumyl peroxide, 2,5-dimethyl-2,5-bis (t-butylperoxy) hexane, α, α'-bis (T-butylperoxy) diisopropylbenzene, t-butylcumyl peroxide, di-t-butyl peroxide, 2,5-dimethyl-2,5-bis (t-butylperoxy) hexin-3, isobutyrylper Oxide, 3,5,5-trimethylhexanoyl peroxide, octanoyl peroxide, lauroyl peroxide, lauric acid peroxide, m-tolu oil peroxide, benzoyl peroxide, diisopropylperoxydicarbonate, bis (4-t) -Butylcyclohexyl) peroxydicarbonate, di-3-methoxybutyl peroxydicarbonate, di-2-ethylhexyl peroxydicarbonate, di-sec-butylperoxydicarbonate, di (3-methyl-3-methoxybutyl) ) Peroxydicarbonate, di (4-t-butylcyclohexyl) peroxydicarbonate, α, α'-bis (neodecanoyl peroxy) diisopropylbenzene, cumylperoxy neodecanoate, 1,1,3 3,-Tetramethylbutylperoxyneodecanoeate, 1-cyclohexyl-1-methylethylperoxyneodecanoeate, t-hexylperoxyneodecanoe T, t-butylperoxyneodecanoate, t-hexylperoxypivalate, t-butylperoxypivalate, 2,5-dimethyl-2,5-bis (2-ethylhexanoylperoxy) hexane , 1,1,3,3-Tetramethylbutylperoxy-2-ethylhexanoate, 1-cyclohexyl-1-methylethylperoxy-2-ethylhexanoate, t-hexylperoxy-2-ethylhexanoate Ate, t-butylperoxy-2-ethylhexanoate, t-butylperoxyisobutyrate, t-butylperoxymaleic acid, t-butylperoxylaurate, t-butylperoxy-3,5 , 5-trimethylhexanoate, t-butylperoxyisopropyl monocarbonate, t-butylperoxy-2-ethylhexyl monocarbonate, 2,5-dimethyl-2,5-bis (benzoylperoxy) hexane, t-butyl Peroxyacetate, t-hexylperoxybenzoate, t-butylperoxy-m-toroil benzoate, t-butylperoxybenzoate, bis (t-butylperoxy) isophthalate, t-butylperoxyallyl monocarbonate, Examples thereof include 3,3', 4,4'-tetra (t-butylperoxycarbonyl) benzophenone and the like. These can be used alone or in combination of two or more. Among these organic peroxides, dicumyl peroxide, 2,5-dimethyl-2,5-bis (t-butylperoxy) hexane, α, α'-bis (t-butylperoxy) diisopropylbenzene Etc. are preferable.

Examples of the imidazole compound include 2-ethyl-4-methylimidazole, 2-methylimidazole, 2-ethylimidazole, 2,4-dimethylimidazole, 2-undecylimidazole, 2-heptadecylimidazole, 2-phenylimidazole, and the like. 2-Phenyl-4-methylimidazole, 1-benzyl-2-methylimidazole, 2-phenyl-4,5-dihydroxymethylimidazole, 2-phenyl-4-methyl-5-hydroxymethylimidazole, 1-vinyl-2- Methylimidazole, 1-propyl-2-methylimidazole, 2-isopropylimidazole, 1-cyanomethyl-2-methyl-imidazole, 1-cyanoethyl-2-ethyl-4-methylimidazole, 1-cyanoethyl-2-undecylimidazole, Examples thereof include 1-cyanoethyl-2-phenylimidazole. Of these, 1-cyanoethyl-2-phenylimidazole and 2-ethyl-4-methylimidazole are preferable because of their high solubility in the adhesive composition of the present embodiment. These can be used alone or in combination of two or more.

Examples of the phosphine compound include primary phosphine, secondary phosphine, tertiary phosphine and the like. Specific examples of the primary phosphine include alkylphosphine such as ethylphosphine and propylphosphine, and phenylphosphine. Specific examples of the secondary phosphine include dialkylphosphine such as dimethylphosphine and diethylphosphine, and secondary phosphine such as diphenylphosphine, methylphenylphosphine and ethylphenylphosphine. Examples of the tertiary phosphine include trialkylphosphine such as trimethylphosphine, triethylphosphine, tributylphosphine, and trioctylphosphine, tricyclohexylphosphine, triphenylphosphine, alkyldiphenylphosphine, dialkylphenylphosphine, tribenzylphosphine, tritrylphosphine, and tri. Examples thereof include -p-styrylphosphine, tris (2,6-dimethoxyphenyl) phosphine, tri-4-methylphenylphosphine, tri-4-methoxyphenylphosphine, and tri-2-cyanoethylphosphine. Of these, tertiary phosphine is preferably used. These can be used alone or in combination of two or more.

Examples of the phosphonium salt compound include compounds having a tetraphenylphosphonium salt, an alkyltriphenylphosphonium salt, a tetraalkylphosphonium and the like, and specific examples thereof include tetraphenylphosphonium-thiocyanate and tetraphenylphosphonium-tetra-p-methylphenylborate. , Butyltriphenylphosphonium-thiocyanate, tetraphenylphosphonium-phthalic acid, tetrabutylphosphonium-1,2-cyclohexyldicarboxylic acid, tetrabutylphosphonium-1,2-cyclohexyldicarboxylic acid, tetrabutylphosphonium-lauric acid, etc. Can be mentioned. These can be used alone or in combination of two or more.

The content of the component (D) is not particularly limited, but is preferably 0.1 to 10.0 parts by mass, more preferably 1.0 to 5.0 parts by mass with respect to 100 parts by mass of the component (A).

The preparation of the adhesive composition of the present embodiment is carried out according to a generally adopted method. Examples of the preparation method include methods such as melt mixing, powder mixing, and solution mixing. In this case, other than the essential components of the present embodiment, for example, a mold release agent, a flame retardant, an ion trap agent, an antioxidant, an adhesive imparting agent, a low stress agent, a coloring agent, a coupling agent, etc. It may be blended as long as the effect of the present invention is not impaired. Moreover, the adhesive composition of this embodiment may contain a resin other than the above-mentioned component (A) such as an epoxy resin, an acrylate compound, a vinyl compound, a benzoxazine compound, and a bismaleimide compound.

(Release agent)
The mold release agent is added to improve the mold release property from the mold. Examples of the release agent include carnauba wax, rice wax, candelilla wax, polyethylene, polyethylene oxide, polypropylene, montanic acid, montanic acid and saturated alcohol, 2- (2-hydroxyethylamino) ethanol, ethylene glycol, glycerin and the like. All known ester compounds such as montanic wax, stearic acid, stearic acid ester, and stearic acid amide can be used. These can be used alone or in combination of two or more.

(Flame retardants)
The flame retardant is added to impart flame retardancy, and all known flame retardants can be used and are not particularly limited. Examples of the flame retardant include phosphazene compounds, silicon compounds, zinc molybdate-supported talc, zinc molybdate-supported zinc oxide, aluminum hydroxide, magnesium hydroxide, molybdate and the like. These can be used alone or in combination of two or more.

(Ion trap agent)
The ion trap agent is added to capture ionic impurities contained in the liquid resin composition and prevent thermal deterioration and hygroscopic deterioration. Any known ion trapping agent can be used and is not particularly limited. Examples of the ion trap agent include hydrotalcites, bismuth hydroxide compounds, rare earth oxides and the like. These can be used alone or in combination of two or more.

<Cured product>
The cured product of the present embodiment is a cured product of the adhesive composition of the present embodiment. Specifically, it can be obtained by heat-treating the adhesive composition at about 150 to 250 ° C. for about 5 minutes to 3 hours.

The shape of the cured product of the present embodiment is not particularly limited, but when it is used for adhering a base sheet, it can be formed into a sheet having a film thickness of usually about 1 to 100 μm, preferably about 3 to 50 μm. The film thickness can be adjusted as appropriate according to the application.

<Adhesive sheet>
The adhesive sheet of the present embodiment is obtained by applying the adhesive composition of the present embodiment to a sheet base material and drying it. Examples of the sheet base material include polyimide, polyimide-silica hybrid, polyamide, polyethylene (PE), polypropylene (PP), polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polymethyl methacrylate resin (PMMA), and the like. Aromatic polyester resin (so-called) obtained from polystyrene resin (PSt), polycarbonate resin (PC), acrylonitrile-butadiene-styrene resin (ABS), ethylene terephthalate, phenol, phthalic acid, hydroxynaphthoic acid, etc. and parahydroxybenzoic acid. Liquid crystal polymers; organic substrates such as "Vexter" manufactured by Kuraray Co., Ltd.) are mentioned, and among these, a polyimide film, particularly a polyimide-silica hybrid film, is preferable from the viewpoint of heat resistance and dimensional stability. Further, the thickness of the sheet base material can be appropriately set according to the application.

<Laminated body>
The laminate of the present embodiment is obtained by further thermocompression bonding the sheet base material to the adhesive surface of the adhesive sheet. As the sheet base material, metals such as glass, iron, aluminum, 42 alloys and copper, and inorganic base materials such as ITO, silicon and silicon carbide are suitable, and the thickness thereof can be appropriately set according to the intended use. Moreover, the laminated body may be further heat-treated.

<Flexible printed circuit board and flexible printed wiring board>
The flexible printed circuit board of the present embodiment uses the above-mentioned laminated body, and is obtained by further adhering the adhesive surface of the above-mentioned adhesive sheet to the inorganic base material surface of the laminated body. The flexible printed substrate preferably uses a polyimide film as an organic base material and a metal foil (particularly copper foil) as an inorganic base material. Then, the metal surface of the flexible printed circuit board is soft-etched to form a circuit, and the adhesive sheet is further attached to the circuit and heat-pressed to obtain a flexible printed wiring board.

Hereinafter, the present invention will be specifically described with reference to Examples and Comparative Examples, but the present invention is not limited thereto. In each example, parts and% are based on mass unless otherwise specified.

<Manufacturing example 1>
In a 1 L flask container equipped with a cooler, a nitrogen introduction tube, a thermocouple, and a stirrer, 52.8 parts by mass of pyromellitic anhydride (manufactured by Daicel Co., Ltd.) and mesitylene (manufactured by Toyo Synthetic Industry Co., Ltd.) 432. 5 parts by mass and 94.0 parts by mass of ethanol (manufactured by Wako Pure Chemical Industries, Ltd.) were added. After charging, the temperature was raised to 80 ° C., the temperature was kept warm for 0.5 hours, and 176.7 parts by mass of dimer diamine (trade name "PRIAMINE 1075", manufactured by Croda Japan Co., Ltd.) was added dropwise. After the dropping, 3.7 parts by mass of methanesulfonic acid (manufactured by Wako Pure Chemical Industries, Ltd.) was added. After that, the temperature was raised to 165 ° C., and a dehydration ring closure reaction was carried out at 165 ° C. for 1 hour to remove water and ethanol in the reaction solution to obtain an intermediate polyimide resin. Subsequently, the obtained polyimide resin was cooled to 130 ° C., 23.4 parts by mass of maleic anhydride (manufactured by Fuso Chemical Industry Co., Ltd.) was added, the temperature was raised to 165 ° C., and the dehydration ring closure reaction was carried out at 165 ° C. for 4 hours. Was carried out to remove water in the reaction solution to obtain a bismaleimide resin.

The obtained bismaleimide resin was put into a separating funnel, 1000 parts by mass of pure water was added, and the separating funnel was shaken and allowed to stand. After standing, the aqueous layer and the organic layer were separated, and then only the organic layer was recovered. The recovered organic layer is placed in a 1 L glass container equipped with a cooler, a nitrogen introduction tube, a heat transfer device, a stirrer, and a vacuum pump, heated to 88 to 93 ° C., water is removed, and then heated to 130 ° C. The temperature was raised and the solvent was removed for 1 hour under a reduced pressure of −0.1 MPa. After removing the solvent, cool to 100 ° C. to normal pressure, add 135.9 parts by mass of toluene (manufactured by Yamaichi Chemical Industry Co., Ltd.), and add a solution of bismaleimide resin (A-1) (nonvolatile content). Was obtained (59.8% by mass).

<Manufacturing example 2>
In the same reaction vessel as in Production Example 1, 66.7 parts by mass of 4,4'-oxydiphthalic anhydride (manufactured by Wako Pure Chemical Industries, Ltd.) and 426.0 parts by mass of mesitylene (manufactured by Toyo Synthetic Industry Co., Ltd.) , And ethanol (manufactured by Wako Pure Chemical Industries, Ltd.) 91.2 parts by mass were added. After charging, the temperature was raised to 80 ° C., the temperature was kept warm for 0.5 hours, and 159.0 parts by mass of dimer diamine (trade name "PRIAMINE 1075", manufactured by Croda Japan Co., Ltd.) was added dropwise. After the dropping, 3.3 parts by mass of methanesulfonic acid (manufactured by Wako Pure Chemical Industries, Ltd.) was added. After that, the temperature was raised to 165 ° C., and a dehydration ring closure reaction was carried out at 165 ° C. for 1 hour to remove water and ethanol in the reaction solution to obtain an intermediate polyimide resin. Subsequently, the obtained polyimide resin was cooled to 130 ° C., 21.1 parts by mass of maleic anhydride (manufactured by Fuso Chemical Industry Co., Ltd.) was added, the temperature was raised to 165 ° C., and the dehydration ring closure reaction was carried out at 165 ° C. for 4 hours. Was carried out to remove water in the reaction solution to obtain a bismaleimide resin.

The obtained bismaleimide resin was put into a separating funnel, 1000 parts by mass of pure water was added, and the separating funnel was shaken and allowed to stand. After standing, the aqueous layer and the organic layer were separated, and then only the organic layer was recovered. The recovered organic layer is placed in a 1 L glass container equipped with a cooler, a nitrogen introduction tube, a heat transfer device, a stirrer, and a vacuum pump, heated to 88 to 93 ° C., and after removing water, the temperature is raised to 150 ° C. The temperature was raised and the solvent was removed for 1 hour under a reduced pressure of −0.1 MPa. After removing the solvent, cool to 100 ° C. to normal pressure, add 122.3 parts by mass of toluene (manufactured by Yamaichi Chemical Industry Co., Ltd.), and add a solution of bismaleimide resin (A-2) (nonvolatile content). Was obtained (59.9% by mass).

<Manufacturing example 3>
In the same reaction vessel as in Production Example 1, 3,3', 4,4'-biphenyltetracarboxylic acid dianhydride (manufactured by Wako Pure Chemical Industries, Ltd.) 63.2 parts by mass, mesitylene (Toyo Synthetic Industry Co., Ltd.) ) 419.6 parts by mass and ethanol (manufactured by Wako Pure Chemical Industries, Ltd.) 90.1 parts by mass were added. After charging, the temperature was raised to 80 ° C., the temperature was kept warm for 0.5 hours, and 159.0 parts by mass of dimer diamine (trade name "PRIAMINE 1075", manufactured by Croda Japan Co., Ltd.) was added dropwise. After the dropping, 3.3 parts by mass of methanesulfonic acid (manufactured by Wako Pure Chemical Industries, Ltd.) was added. After that, the temperature was raised to 165 ° C., and a dehydration ring closure reaction was carried out at 165 ° C. for 1 hour to remove water and ethanol in the reaction solution to obtain an intermediate polyimide resin. Subsequently, the obtained polyimide resin was cooled to 130 ° C., 21.1 parts by mass of maleic anhydride (manufactured by Fuso Chemical Industry Co., Ltd.) was added, the temperature was raised to 165 ° C., and the dehydration ring closure reaction was carried out at 165 ° C. for 4 hours. Was carried out to remove water in the reaction solution to obtain a bismaleimide resin.

The obtained bismaleimide resin was put into a separating funnel, 1000 parts by mass of pure water was added, and the separating funnel was shaken and allowed to stand. After standing, the aqueous layer and the organic layer were separated, and then only the organic layer was recovered. The recovered organic layer is placed in a 1 L glass container equipped with a cooler, a nitrogen introduction tube, a heat transfer device, a stirrer, and a vacuum pump, heated to 88 to 93 ° C., and after removing water, the temperature is raised to 150 ° C. The temperature was raised and the solvent was removed for 1 hour under a reduced pressure of −0.1 MPa. After removing the solvent, cool to 100 ° C. to normal pressure, add 120.5 parts by mass of toluene (manufactured by Yamaichi Chemical Industry Co., Ltd.), and add a solution of bismaleimide resin (A-3) (nonvolatile content). Was obtained (59.3% by mass).

<Manufacturing example 4>
4,4'-[Propane-2,2-diylbis (1,4-phenyleneoxy)] diphthalic acid dianhydride (trade name "BISDA1000", SABIC Innovative Plastics Japan Joint) in the same reaction vessel as in Production Example 1. 91.0 parts by mass (manufactured by the company), 415.3 parts by mass of mecitylene (manufactured by Toyo Synthetic Industry Co., Ltd.), and 86.7 parts by mass of ethanol (manufactured by Wako Pure Chemical Industries, Ltd.) were added. After charging, the temperature was raised to 80 ° C., the temperature was kept warm for 0.5 hours, and 129.6 parts by mass of dimer diamine (trade name "PRIAMINE 1075", manufactured by Croda Japan Co., Ltd.) was added dropwise. After the dropping, 2.7 parts by mass of methanesulfonic acid (manufactured by Wako Pure Chemical Industries, Ltd.) was added. After that, the temperature was raised to 165 ° C., and a dehydration ring closure reaction was carried out at 165 ° C. for 1 hour to remove water and ethanol in the reaction solution to obtain an intermediate polyimide resin. Subsequently, the obtained polyimide resin was cooled to 130 ° C., 17.2 parts by mass of maleic anhydride (manufactured by Fuso Chemical Industry Co., Ltd.) was added, the temperature was raised to 165 ° C., and the dehydration ring closure reaction was carried out at 165 ° C. for 4 hours. Was carried out to remove water in the reaction solution to obtain a bismaleimide resin.

The obtained bismaleimide resin was put into a separating funnel, 1000 parts by mass of pure water was added, and the separating funnel was shaken and allowed to stand. After standing, the aqueous layer and the organic layer were separated, and then only the organic layer was recovered. The recovered organic layer is placed in a 1 L glass container equipped with a cooler, a nitrogen introduction tube, a heat transfer device, a stirrer, and a vacuum pump, heated to 88 to 93 ° C., and after removing water, the temperature is raised to 150 ° C. The temperature was raised and the solvent was removed for 1 hour under a reduced pressure of −0.1 MPa. After removing the solvent, cool to 100 ° C. to normal pressure, add 119.3 parts by mass of toluene (manufactured by Yamaichi Chemical Industry Co., Ltd.), and add a solution of bismaleimide resin (A-4) (nonvolatile content). Was obtained (59.5% by mass).

<Comparative manufacturing example 1>
In the same reaction vessel as in Production Example 1, 36.5 parts by mass of pyromellitic anhydride (manufactured by Daicel Corporation), 429.0 parts by mass of mesitylene (manufactured by Toyo Synthetic Industry Co., Ltd.), and ethanol (Wako Pure Chemical Industries, Ltd.) 88.7 parts by mass (manufactured by Co., Ltd.) was charged. After charging, the temperature was raised to 80 ° C. and kept warm for 0.5 hours, and α, ω-bis (3-aminopropyl) polydimethylsiloxane (trade name "KF-8010", manufactured by Shin-Etsu Chemical Co., Ltd.) 191. 6 parts by mass was added dropwise. After the dropping, 2.6 parts by mass of methanesulfonic acid (manufactured by Wako Pure Chemical Industries, Ltd.) was added. After that, the temperature was raised to 165 ° C., and a dehydration ring closure reaction was carried out at 165 ° C. for 1 hour to remove water and ethanol in the reaction solution to obtain an intermediate polyimide resin. Subsequently, the obtained polyimide resin was cooled to 130 ° C., 16.4 parts by mass of maleic anhydride (manufactured by Fuso Chemical Industry Co., Ltd.) was added, the temperature was raised to 165 ° C., and the dehydration ring closure reaction was carried out at 165 ° C. for 4 hours. Was carried out to remove water in the reaction solution to obtain a bismaleimide resin.

The obtained bismaleimide resin was put into a separating funnel, 1000 parts by mass of pure water was added, and the separating funnel was shaken and allowed to stand. After standing, the aqueous layer and the organic layer were separated, and then only the organic layer was recovered. The recovered organic layer is placed in a 1 L glass container equipped with a cooler, a nitrogen introduction tube, a heat transfer device, a stirrer, and a vacuum pump, heated to 88 to 93 ° C., and after removing water, the temperature is raised to 150 ° C. The temperature was raised and the solvent was removed for 1 hour under a reduced pressure of −0.1 MPa. After removing the solvent, cool to 100 ° C. to normal pressure, add 123.2 parts by mass of toluene (manufactured by Yamaichi Chemical Industry Co., Ltd.), and add a solution of bismaleimide resin (X) (nonvolatile content is 59). .7% by mass) was obtained.

PMDA: Pyromellitic anhydride ODPA: 4,4'-oxydiphthalic anhydride BPDA: 3,3', 4,4'-biphenyltetracarboxylic acid dianhydride BISDA: 4,4'-[Propane-2,2- Diylbis (1,4-phenyleneoxy)] Diphthalic acid dianhydride PRIAMINE: Dimerdiamine KF8010: α, ω-bis (3-aminopropyl) polydimethylsiloxane

<Physical characteristic evaluation method>
(Weight average molecular weight (Mw))
The weight average molecular weight (Mw) was measured by GPC (gel permeation chromatography). A sample in which bismaleimide resin was dissolved in tetrahydrofuran (THF) to a concentration of 3% by mass was heated to 30 ° C., a column (GL-R420 (manufactured by Hitachi High-Tech Fielding Corporation) x 1, GL-R430. Inject 50 μL into (Hitachi High-Tech Fielding Co., Ltd.) x 1 and GL-R440 (Hitachi High-Tech Fielding Co., Ltd.) x 1), use THF as the developing solvent, and measure at a flow rate of 1.6 mL / min. went. An L-3350 RI detector (manufactured by Hitachi, Ltd.) was used as the detector, and the weight average molecular weight (Mw) was measured from the elution time using a molecular weight / elution time curve prepared using standard polystyrene (manufactured by Tosoh Corporation). ) Was converted.

[Example 1]
In a 225 ml cylindrical container, 100 parts by mass of the solution of the bismaleimide resin (A-1) obtained in Production Example 1, and a silica-containing slurry as a component (B) (manufactured by Admatex Co., Ltd.), trade name "SC2050-""KNK", silica 70% by mass) 21.4 parts by mass, and 20.0 parts by mass of methyl isobutyl ketone (manufactured by Wako Pure Chemical Industries, Ltd.) was charged as the component (C). Subsequently, the container is covered, and the mixture in the container is stirred at 70 rpm for 4 hours or more using a variable mix rotor (manufactured by AS ONE Co., Ltd., product number "VMR-5R") to obtain a non-volatile content of 52.9. A mass% adhesive composition was obtained.

[Examples 2 to 8]
As the component (A), the component (B), the component (C), and the component (D), the types shown in Table 2 were used in the amounts shown in the same table, respectively, in the same manner as in Example 1, respectively. An adhesive composition was obtained.

[Comparative Example 1]
In Example 1, instead of the solution of the component (A-1), the solution of the component (X) is used in the amount shown in Table 2, and the types shown in Table 2 are used as the component (B) and the component (C). An adhesive composition was obtained in the same manner as in Example 1 except that each of the above was used in the amounts shown in the same table.

[Comparative Example 2]
An adhesive composition was obtained in the same manner as in Example 1 except that the amount of the component (B) used was changed to the amount shown in Table 2.

SC2050-KNK: Silica-containing slurry (manufactured by Admatex Co., Ltd., 70% by mass of silica, silica particles surface-treated with phenylaminosilane, average particle size 0.4 μm)
MIBK: Methyl isobutyl ketone (manufactured by Wako Pure Chemical Industries, Ltd.)
2E4MZ: 2-Ethyl-4-methylimidazole (manufactured by Wako Pure Chemical Industries, Ltd.)

(Example 9)
In a 225 ml cylindrical container, 100 parts by mass of the solution of the bismaleimide resin (A-1) obtained in Production Example 1, and a slurry containing silica as the component (B) (manufactured by Admatex Corporation, trade name "SC2050-""KNK", silica 70% by mass) 42.7 parts by mass, 25.0 parts by mass of methyl isobutyl ketone (manufactured by Wako Pure Chemical Industries, Ltd.) as a component (C), homomixer (manufactured by Primix Corporation, "T" .K. Homomixer MARKII ”) was used to stir at 9000 rpm for 20 minutes. After that, 0.60 parts by mass of Dikmyl Peroxide (manufactured by NOF CORPORATION, trade name "Park Mill D") was added as a component (D), and a variable mix rotor (manufactured by AS ONE Co., Ltd., product number "VMR-5R") was added. An adhesive composition having a non-volatile content of 53.6% by mass was obtained by stirring at 70 rpm for 1 hour or more.

[Examples 10 to 19]
As the component (A), the component (B), the component (C) and the component (D), the types shown in Table 3 were used in the amounts shown in the same table, respectively, and the same as in Example 9 was used. An adhesive composition was obtained.

3SX-CX1: Silica-containing slurry (manufactured by Admatex Co., Ltd., silica 60.5% by mass, silica particles surface-treated with phenylaminosilane, average particle size 0.3 μm)
YA050C-KJK: Silica-containing slurry (manufactured by Admatex Co., Ltd., silica 51.0% by mass, silica particles surface-treated with phenylaminosilane, average particle size 50 nm)
DCP: Dicumyl peroxide (manufactured by NOF CORPORATION)

<Preparation of adhesive sheet (1)>
The adhesive composition of Example 1 was placed on a film binar (registered trademark) (PET film, manufactured by Fujimori Kogyo Co., Ltd., trade name "NS14", film thickness 75 μm) using an applicator, and 30 μm after drying. The film was applied to a thickness and dried at 130 ° C. for 20 minutes using an oven to prepare an adhesive sheet (1). An adhesive sheet (1) was obtained in the same manner for the adhesive compositions of the other examples and comparative examples.

<Preparation of cured sheet (1)>
A polyimide film (trade name "100EN", manufactured by Toray DuPont Co., Ltd., thickness 25 μm) is superposed on the adhesive surface of the adhesive sheet (1) of Example 1, and a vacuum laminator is used at 75 ° C., 0.5 MPa, 30. Thermocompression bonding was performed under the condition of seconds. After thermocompression bonding, the PET film was peeled off and heat-treated at 200 ° C. for 2 hours in a hot air dryer to obtain a cured sheet (1). A cured sheet (1) was obtained in the same manner for the adhesive compositions of the other examples and the comparative examples.

<Preparation of cured sheet (2)>
The adhesive composition of Example 1 was placed on sepanium (manufactured by Toyo Aluminum K.K., trade name "50B2-EA (A) 4G / M2", film thickness 50 μm) using an applicator, and 100 μm after drying. It was applied to a thickness and dried in an oven at 130 ° C. for 20 minutes. Then, the heat treatment was performed at 200 ° C. for 1 hour using an oven. After the heat treatment, the mixture was cooled to room temperature and exfoliated from sepanium to obtain a cured sheet (2).

<Preparation of laminated body (1)>
The roughened surface of the copper foil adheres the adhesive sheet (1) of Example 1 from which the PET film has been peeled off and two copper foils (trade name "F2WS-18", manufactured by Furukawa Denko Co., Ltd., thickness 18 μm). Laminated body (1) in which copper foil, cured product of adhesive sheet, and copper foil are laminated in this order by laminating so as to face the sheet and thermocompression bonding at 200 ° C., 2 MPa, and 2 hours with a hot press. Got The laminated body (1) was obtained in the same manner for the adhesive compositions of the other examples and the comparative examples.

<Preparation of laminated body (2)>
The adhesive sheet (1) of Example 1 from which the PET film was peeled off and two polyimide films (trade name "100EN", manufactured by Toray DuPont Co., Ltd., thickness 25 μm) were laminated so that the adhesive sheet was in the center. Then, the polyimide film, the cured product of the adhesive sheet, and the polyimide film were laminated in this order by thermocompression bonding at 200 ° C., 2 MPa, and 2 hours with a hot press to obtain a laminate (2). The laminated body (2) was obtained in the same manner for the adhesive compositions of the other examples and the comparative examples.

<Evaluation of tackiness>
A glossy surface of copper foil (trade name "F2WS-18", manufactured by Furukawa Electric Co., Ltd., thickness 18 μm) was superposed on the adhesive surface of the cured sheet (1), and the copper foil was moved in the horizontal direction. At that time, when the copper foil was sticky and could not be moved, it was considered to have tackiness, and when it could be moved in the horizontal direction, it was considered to have no tackiness.

<Adhesive strength>
The adhesive strength with the polyimide film and the copper foil was measured using the laminated body (1) and the laminated body (2). The adhesive strength was measured at a tensile speed of 5 mm / s at room temperature using a 90 ° peeling measuring machine (manufactured by Yamaden Co., Ltd., RHEONERII CREEP METER RE2-3305B). The results are shown in Tables 4 and 5.

<Criteria for judging adhesive strength>
A: Adhesive strength is 1.0 kN / m or more B: Adhesive strength is 0.5 kN / m or more and less than 1.0 kN / m C: Adhesive strength is less than 0.5 kN / m

<Permittivity and dielectric loss tangent>
The copper foils on both sides of the laminate (1) were removed by etching, dried at 130 ° C. for 30 minutes, and then a 10 cm × 5 cm test piece was prepared and used at 10 GHz with an SPDR dielectric resonator (manufactured by Agilent Technologies). Relative permittivity and dielectric loss tangent were measured. The results are shown in Tables 4 and 5. In Comparative Example 1, it was difficult to prepare a test piece by etching, so that the measurement could not be performed.

<5% weight loss temperature>
The copper foils on both sides of the laminate (1) are removed by etching, dried at 130 ° C. for 30 minutes, and then the cured product of the adhesive sheet is placed in an open sample container (“P / N SSC000E030” manufactured by Seiko Electronics Co., Ltd.) 6 A measurement of 0.0 to 10.0 mg was performed under the conditions of a nitrogen flow rate of 300 mL / min and a heating rate of 10 ° C./min, and a 5% weight loss temperature (Td5) was measured. As the measuring device, TG / DTA7200 (manufactured by Hitachi High-Tech Science Corporation) was used. The results are shown in Tables 4 and 5.

<Coefficient of linear expansion (CTE) α ₁ , α ₂ >
A test piece having a size of 30 mm × 4 mm was prepared from the cured sheet (2). Using this test piece, the coefficient of linear expansion (CTE) was measured using a thermomechanical analyzer (trade name "TMA / SS7100", manufactured by Hitachi High-Tech Science Co., Ltd.). The measurement mode is the tension mode, the measurement load is 20 to 49 mN, the measurement atmosphere is the atmosphere, the temperature rise rate is 10 ° C / min for the 1st run, 5 ° C / min for the 2nd run, and the measurement results at 40 to 55 ° C for the 2nd run. Was α ₁ , and the measurement result at 110 to 160 ° C was α ₂ . The results are shown in Tables 4 and 5.

As is clear from Tables 4 and 5, the bismaleimide resin (A) and the inorganic filler (B) of the present embodiment are contained, and the content of the inorganic filler (B) is 5 to 55% by mass. It was confirmed that the adhesive composition (Example) within the range of (based on the total solid content of the adhesive composition) not only has excellent low dielectric properties, but also exhibits high adhesive strength with copper foil and polyimide film. rice field. Furthermore, it was confirmed that the cured product obtained by using the adhesive composition of the example had a low tack, a high 5% weight loss temperature, and a small amount of outgas. Furthermore, it was confirmed that the coefficient of linear expansion (CTE) of the cured product obtained by using the adhesive composition of the example was reduced. In Examples 14 to 19, the dielectric properties are as effective as those in the other examples.

The adhesive composition of the present invention is excellent not only in low dielectric properties in the high frequency band but also in adhesiveness to substrates such as copper foil and polyimide sheet. Further, the cured product (adhesive layer) obtained from the adhesive composition has a low tack, a high 5% weight loss temperature, a small amount of outgas, and a low linear expansion coefficient (CTE), so that it is a printed circuit board. Not only as an adhesive used for manufacturing (build-up boards, flexible printed wiring boards, etc.) and copper-clad boards for flexible printed wiring boards, but also as electrical insulating materials such as semiconductor interlayer materials, coating agents, resist inks, and conductive pastes. Is also useful.

Claims (15)

It contains a bismaleimide resin (A) obtained by reacting an aromatic tetracarboxylic acid (a1), a diamine diamine (a2), and a maleic anhydride (a3), and an inorganic filler (B).
A bismaleimide-based adhesive composition in which the content of the inorganic filler (B) is 5 to 55% by mass based on the total solid content of the adhesive composition. The bismaleimide-based adhesive composition according to claim 1, wherein the aromatic tetracarboxylic acids (a1) are pyromellitic anhydride or a compound represented by the following general formula (1).

[In formula (1), X represents a single bond or at least one group selected from the following groups. ]

The bismaleimide-based adhesive composition according to claim 1 or 2, wherein the dimer diamine (a2) is a compound represented by the following general formula (2) and / or general formula (2').

[In equations (2) and (2'), m, n, p and q represent integers of 1 or more selected so that m + n = 6 to 17 and p + q = 8 to 19, respectively, and are shown by broken lines. The bond means a carbon-carbon single bond or a carbon-carbon double bond. However, when the bond shown by the broken line is a carbon-carbon double bond, the formulas (2) and (2') indicate the number of hydrogen atoms bonded to each carbon atom constituting the carbon-carbon double bond. The structure is obtained by subtracting one from the numbers shown in the formulas (2) and (2'). ] The bismaleimide-based adhesive composition according to any one of claims 1 to 3, wherein the bismaleimide resin (A) has a weight average molecular weight of 3000 to 25000. The bismaleimide-based adhesive composition according to any one of claims 1 to 4, wherein the inorganic filler is silica. The bismaleimide-based adhesive composition according to any one of claims 1 to 5, further comprising a polymerization initiator (D). The bismaleimide-based adhesive composition according to claim 6, wherein the polymerization initiator (D) is at least one selected from the group consisting of an organic peroxide, an imidazole compound, a phosphine compound, and a phosphonium salt compound. The bismaleimide-based adhesive composition according to any one of claims 1 to 7, wherein the inorganic filler (B) has an average particle size of 100 nm to 10 μm. The bismaleimide-based adhesive composition according to any one of claims 1 to 8, wherein the inorganic filler (B) has an average particle size of 200 nm to 1.0 μm. The bismaleimide-based adhesive composition according to any one of claims 1 to 9, wherein the content of the inorganic filler (B) is 5 to 25% by mass based on the total solid content of the adhesive composition. thing. A cured product obtained by curing the bismaleimide-based adhesive composition according to any one of claims 1 to 10. An adhesive sheet obtained by applying the bismaleimide-based adhesive composition according to any one of claims 1 to 10 to a sheet substrate and drying it. A laminate obtained by thermocompression bonding a sheet base material to the adhesive surface of the adhesive sheet according to claim 12. A laminate obtained by further heating the laminate according to claim 13. A flexible printed wiring board using the laminate according to claim 14.