JP2024043511A - Adhesive film for build-up boards - Google Patents

Abstract

[Problem] To provide an adhesive film for build-up boards, which is a polyimide-based interlayer insulating material, is soluble in low-boiling point solvents, can be processed into a film at low temperatures, and has excellent heat resistance and dimensional stability to satisfy connection reliability between terminals. [Solution] An adhesive film for build-up boards, which is used as an interlayer insulating film for build-up boards and contains a polyimide that is soluble in an organic solvent composed of an acid dianhydride component and a diamine component, and which contains, as essential components, as the diamine component, a long-chain aliphatic diamine component having 24 to 48 carbon atoms, and at least one aromatic diamine component selected from a meta-position linked aromatic diamine component and a fluorene skeleton diamine component. [Selected Figure] None

Description

The present invention relates to an adhesive film for build-up substrates (also known as a build-up film), and particularly to an adhesive film for build-up substrates made of polyimide soluble in organic solvents.

Due to the demand for high functionality and miniaturization of electrical and electronic devices, the build-up method, in which the base substrate and the insulating layer are sequentially processed and laminated layer by layer, has become widely used as a mounting method that supports high-density mounting. There is. When designing multilayer high-density wiring on a built-up wiring board, in order to ensure connection reliability between each board terminal, the interlayer insulation material (insulating adhesive film) incorporated into the multilayer board must have heat resistance and dimensional stability. is required.

Conventionally, epoxy resins have been mainly used as interlayer insulating materials for build-up boards (see, for example, Patent Documents 1 and 5). However, epoxy resins have insufficient flexibility and dimensional stability problems. In addition, there is a limit to the low dielectric loss tangent (Df) required for transmitting high-frequency signals in the GHz range.
On the other hand, polyimide-based interlayer insulating materials are also known, but they usually require processing temperatures of over 200° C., which may adversely affect the substrate. For this reason, a composition using an epoxy resin and a polyimide in combination has been proposed (Patent Document 2).
In addition, polyimides using aliphatic diamines and aromatic diamines in combination have been proposed as adhesive films for coverlay films, bonding sheets, etc., rather than for build-up substrate applications (Patent Documents 3 and 4). However, these polyimide-based materials have low glass transition temperatures, and although they can be used as adhesives for coverlay films, bonding sheets, etc., their reliability as interlayer insulating materials incorporated in build-up substrates cannot be expected.
Furthermore, in order to improve the productivity of adhesive films as interlayer insulating materials in build-up substrates, there is a demand for materials that dissolve in low-boiling point solvents at temperatures below 200°C.

Japanese Patent Application Publication No. 2001-181375 JP 2003-89784 A Japanese Patent Application Publication No. 2018-168370 JP 2021-161387 A Japanese Patent Application Publication No. 2022-121436

The present invention is a polyimide-based interlayer insulating material that can be used as an interlayer insulation material for build-up boards. The purpose of the present invention is to provide an adhesive film for build-up substrates.

式（１）において、Ｘは－Ｏ－、－Ｓ－、－ＣＯ－、－ＳＯ－、－ＳＯ２－、－ＣＯＯ－、－ＣＨ２－、－ＣＨ２－Ｏ－、－Ｃ（ＣＨ３）２－、－ＮＨ－又は－ＣＯＮＨ－から選ばれる２価の基を示し、ｍは０又は１である。式（２）において、ｌは０又は１である。式（１）及び式（２）において、各ベンゼン環は、それぞれ、置換基を有してもよく、置換基としては、独立に、水酸基、フッ素原子、又はフッ素原子で置換されてもよい炭素数１～３のアルキル基若しくはアルコキシ基が挙げられる。 The present inventors have arrived at the present invention as a result of various studies to solve the above-mentioned problems.
That is, the present invention is a heat-resistant adhesive film that is used as an interlayer insulating film of a build-up board and contains an organic solvent-soluble polyimide consisting of an acid dianhydride component and a diamine component, and wherein the diamine component is carbon. An aromatic diamine component selected from a long-chain aliphatic diamine component with numbers 24 to 48, a meta-position-linked aromatic diamine component represented by the following formula (1), and a fluorene skeleton diamine component represented by the following formula (2). This is an adhesive film for a build-up substrate, characterized in that it contains any one or more of the following as an essential component.

In formula (1), X is -O-, -S-, -CO-, -SO-, -SO2-, -COO-, -CH2-, -CH2-O-, -C(CH3)2-, It represents a divalent group selected from -NH- or -CONH-, and m is 0 or 1. In formula (2), l is 0 or 1. In formula (1) and formula (2), each benzene ring may have a substituent, and the substituent is independently a hydroxyl group, a fluorine atom, or a carbon group optionally substituted with a fluorine atom. Examples include 1 to 3 alkyl groups or alkoxy groups.

The present invention is a polyimide precursor or polyimide used in the adhesive film for build-up substrates.
The present invention is a laminated film formed by laminating the above adhesive film for a build-up substrate on a removable support film.

The heat-resistant adhesive film for build-up substrates of the present invention is soluble in low-boiling point solvents and has excellent heat resistance and dimensional stability.

The adhesive film for a build-up substrate of the present invention contains an organic solvent-soluble polyimide consisting of an acid dianhydride component and a diamine component. In this specification, the acid dianhydride component and diamine component also mean reactants (derivatives) derived from the acid dianhydride and diamine used as raw materials.
The polyimide contains, as a diamine component, a long-chain aliphatic diamine component having 24 to 48 carbon atoms, a meta-position-linked aromatic diamine component represented by the following formula (1), and a fluorene skeleton diamine represented by the following formula (2). It is characterized by containing as an essential component at least one aromatic diamine component selected from among the components.

In the present invention, the diamine component constituting the polyimide first contains a long-chain aliphatic diamine component having 24 to 48 carbon atoms as an essential component.
The long-chain aliphatic diamine having 24 to 48 carbon atoms may have a cyclic structure in the molecule, and aliphatic diamine derived from dimer acid (dimer diamine) is preferable. It is an aliphatic diamine obtained by converting the carboxyl group of dimer acid into a hydroxyl group and then converting it into an amino group. For example, it can be obtained by polymerizing unsaturated fatty acids such as oleic acid and linoleic acid to form a dimer acid, reducing this, and then aminating it. Specifically, commercially available products such as aliphatic diamine having 36 carbon atoms (PRIAMINE 1074 manufactured by Croda Japan) can be used.
The long-chain aliphatic diamine component having 24 to 48 carbon atoms is preferably contained in an amount of 30 to 90 mol % based on the total diamine component. More preferably 30 to 70 mol%, still more preferably 30 to 60 mol%.

式（１）において、Ｘは－Ｏ－、－Ｓ－、－ＣＯ－、－ＳＯ－、－ＳＯ２－、－ＣＯＯ－、－ＣＨ２－、－ＣＨ２－Ｏ－、－Ｃ（ＣＨ３）２－、－ＮＨ－又は－ＣＯＮＨ－から選ばれる２価の基を示し、ｍは０又は１である。式（２）において、ｌは０又は１である。式（１）及び式（２）において、各ベンゼン環は、それぞれ、置換基を有してもよく、置換基としては、独立に、水酸基、フッ素原子、又はフッ素原子で置換されてもよい炭素数１～３のアルキル基若しくはアルコキシ基が挙げられる。
上記式（１）のメタ位連結芳香族骨格や式（２）の嵩高いフルオレン骨格を導入することにより、立体的に分子鎖間の相互作用し難い構造を形成し、溶剤可溶性を高めると共に、高い耐熱性、寸法安定性を発現できる。 In the present invention, the diamine component constituting the polyimide secondly contains, as an essential component, at least one aromatic diamine component selected from a meta-position linked aromatic diamine component represented by the following formula (1) and a fluorene skeleton diamine component represented by the following formula (2):

In formula (1), X represents a divalent group selected from -O-, -S-, -CO-, -SO-, -SO2-, -COO-, -CH2-, -CH2-O-, -C(CH3)2-, -NH-, or -CONH-, and m is 0 or 1. In formula (2), l is 0 or 1. In formulas (1) and (2), each benzene ring may have a substituent, and examples of the substituent independently include a hydroxyl group, a fluorine atom, or an alkyl group or alkoxy group having 1 to 3 carbon atoms which may be substituted with a fluorine atom.
By introducing the meta-position-linked aromatic skeleton of the above formula (1) or the bulky fluorene skeleton of the above formula (2), a structure in which interactions between molecular chains are difficult to occur three-dimensionally is formed, and the solvent solubility is increased while high heat resistance and dimensional stability can be achieved.

In formula (1), X is preferably -O-, -S-, -CH2-, -C(CH3)2-. Specifically, the meta-linked aromatic diamine represented by formula (1) includes 1,3-bis(3-aminophenoxy)benzene (APB), 3,3-diaminodiphenyl ether, 3,3'-diamino Examples include diphenyl sulfide, 3,3'-diaminodiphenylmethane, and 3,3'-diaminodiphenylpropane.
The meta-position-linked aromatic diamine component represented by formula (1) preferably has a meta-position content in the molecule of 50% or more, more preferably 70% or more, and even more preferably 90% or more.
The meta-linked aromatic diamine component represented by formula (1) is preferably contained in an amount of 10 to 70 mol % based on the total diamine components. More preferably 30 to 65 mol%, still more preferably 30 to 60 mol%.

Specifically, the fluorene skeleton diamine represented by formula (2) includes 9,9-bis(4-aminophenyl)fluorene (BAFL) and 9,9'-bis(4-amino-3-methylphenyl). Fluorene, 9,9'-bis(4-amino-3-fluorophenyl)fluorene, 9,9'-bis(4-amino-3-hydroxyphenyl)fluorene, 9,9'-bis(4-methyl-3 -aminophenyl)fluorene, 9,9'-bis(4-fluoro-3-aminophenyl)fluorene, 9,9'-bis(4-hydroxy-3-aminophenyl)fluorene, 9,9'-bis[4 -(4-aminophenoxy)phenyl]fluorene and the like.
The fluorene skeleton diamine component represented by (2) is preferably contained in an amount of 40 to 70 mol % based on the total diamine components. More preferably, it is 45 to 60 mol%.

Other diamines can also be blended as the diamine component. For example, m-phenylenediamine, p-phenylenediamine, 4,4'-diaminodiphenylpropane, 4,4'-diaminodiphenylmethane, benzidine, 2,2'-dimethyl-4,4'-diaminobiphenyl, 2,2'-diethyl-4,4'-diaminobiphenyl,2,2'-diethoxy-4,4'-diaminobiphenyl,2,2'-ditrifluoromethylbenzidine,4-aminophenyl-4'-aminobenzoate, 2,2 '-Divinyl-4,4'-diaminobiphenyl, 4,4'-diaminodiphenylsulfide, 4,4'-diaminodiphenylsulfone, 3,3'-diaminodiphenylsulfone, 4,4'-diaminodiphenyl ether, 3,3 '-Diamino diphenyl ether, 4,4'-diamino-p-terphenyl, 2,2-bis(3-aminophenoxyphenyl)propane, 2,2-bis(4-aminophenoxyphenyl)propane, 3,3-bis (3-aminophenoxyphenyl) sulfone, 4,4-bis(3-aminophenoxyphenyl) sulfone, 3,3-bis(4-aminophenoxyphenyl) sulfone, 4,4-bis(4-aminophenoxyphenyl) sulfone , 2,2-bis(3-aminophenoxyphenyl)hexafluoropropane, 2,2-bis(4-aminophenoxyphenyl)hexafluoropropane, 1,4-bis(4-aminophenoxy)benzene, 1,3- Bis(4-aminophenoxy)benzene, 4,4-(p-phenylenediisopropylidene)bisaniline, 4,4-(m-phenylenediisopropylidene)bisaniline, 3,3-[(2,4,5,6 -tetramethyl-1,3-phenylene)bis(methylene)bisaniline, 3,3'-[1,3-phenylenebis(thio)]bisaniline, 3,3'-[1,3-phenylenebis(1-methyl) ethylidene)] bisaniline, and the like.
When blending other diamines, the blending amount is preferably less than 50 mol%, more preferably less than 30 mol%, and even more preferably 10 mol%, based on the total diamine components, so as not to impede the object of the present invention. It is best to keep it below %.

In the present invention, various acid dianhydride (tetracarboxylic dianhydride) components can be used that constitute the polyimide together with the diamine component.
For example, 3,3',4,4'-diphenyl ether tetracarboxylic dianhydride, 3,3',4,4'-diphenylsulfone tetracarboxylic dianhydride, 3,3',4,4'-benzophenone Tetracarboxylic dianhydride, 2,2',2,3'-benzophenonetetracarboxylic dianhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride, 2,3,3', 4'-biphenyltetracarboxylic dianhydride, pyromellitic dianhydride, 1,4,5,8-naphthalenetetracarboxylic dianhydride, 1,2,5,6-naphthalenetetracarboxylic dianhydride, 3,4,9,10-perylenetetracarboxylic dianhydride, 3,3,6,7-anthracenetetracarboxylic dianhydride, 1,2,7,8-phenanthrenetetracarboxylic dianhydride, 4, 4'-(hexafluoroisopylidene) phthalic dianhydride, 2,2-bis[4-(3,4-dicarboxyphenoxy)phenyl]propane dianhydride, 1,4-bis(3,4- Examples include dicarboxyphenoxy)benzene dianhydride, p-phenylene bis(trimellitic acid monoester acid anhydride), and ethylene glycol bisanhydrotrimellitate.
The acid dianhydride component is preferably an acid dianhydride component having a ketone group as an aromatic ring linking group, specifically, 3,3',4,4'-benzophenonetetracarboxylic dianhydride (BTDA). ), 2,2',2,3'-benzophenonetetracarboxylic dianhydride.
The acid dianhydride component having a ketone group as an aromatic ring linking group is preferably contained in an amount of 50 mol % or more based on the total acid dianhydride component. More preferably, it is 70 mol% or more, and still more preferably 90 mol% or more.

Polyimide can be manufactured by a known method by reacting a diamine as a raw material with an acid dianhydride in a solvent to generate a precursor resin, and then ring-closing the resin by heating.
For example, a polyamic acid, which is a polyimide precursor, can be obtained by dissolving approximately equimolar amounts of an acid anhydride and a diamine in an organic solvent, stirring at a temperature of 100° C. or lower for 30 minutes to 24 hours, and causing a polymerization reaction. The amount of organic solvent used is preferably adjusted so that the solid content concentration of the polyimide precursor solution to be produced is within the range of 5 to 30% by weight.

It is usually advantageous to use the synthesized polyimide precursor as a reaction solvent solution, but it can also be concentrated, diluted, or replaced with another organic solvent if necessary. Polyimide precursors are advantageously used because they generally have excellent solvent solubility. The method of imidizing the precursor is not particularly limited, and for example, heat treatment such as heating in a solvent at a temperature in the range of 80 to 300° C. for 1 to 24 hours is preferably employed.

In the present invention, it is desirable to use a ketone solvent (S1) with a boiling point of less than 200° C. and an aromatic hydrocarbon solvent (S2) together as the organic solvent. Imidized water can be efficiently removed during solution imidization to form a polymer, and the solvent can be efficiently removed during film coating in the subsequent process.
Examples of the ketone solvent (S1) include cyclohexanone, 2-butanone, cyclopentanone, methyl isobutyl ketone, diisobutyl ketone, diacetone alcohol, etc., and usually have a boiling point of 140 to 200°C.
Examples of the aromatic hydrocarbon solvent (S2) include xylene, toluene, benzene, ethylbenzene, etc., and usually have a boiling point of 70 to 140°C.
The mixing ratio of the ketone solvent (S1) and the aromatic hydrocarbon solvent (S2) can be selected in the range of 10/90 to 90/10 in terms of mass ratio.

The weight average molecular weight (Mw) of the polyimide of the present invention is, for example, 5,000 to 200,000. When the weight average molecular weight is less than 5,000, it tends to become brittle when formed into a film. On the other hand, if the weight average molecular weight exceeds 200,000, the varnish will have a high viscosity, and there is a possibility that the handling property during blending may be reduced or the fluidity during heating of the film may be impaired.
The weight average molecular weight (Mw) is preferably within the range of 10,000 to 70,000, more preferably within the range of 20,000 to 60,000. When Mw is less than 10,000, the number of highly polar ends increases in the polyimide molecular chain, so that the relative permittivity and dielectric loss tangent may tend to increase. When Mw exceeds 70,000, the molecular chain length becomes long and it becomes difficult to form an ordered structure, so that the relative dielectric constant and dielectric loss tangent may tend to increase.

The polyimide of the present invention is preferably a thermoplastic polyimide. Since polyimide is thermoplastic, it has high adhesion and thermocompression processability, and can be used as an adhesive layer. Here, "thermoplastic polyimide" generally refers to a polyimide that softens by heating, solidifies by cooling, and can repeat this process, and whose glass transition temperature can be clearly confirmed. It means a polyimide whose glass transition temperature can be clearly confirmed in the temperature range of . In addition, from the viewpoint of thermocompression bondability at low temperatures, the thermoplastic polyimide is preferably a polyimide whose glass transition temperature can be clearly confirmed in a temperature range of less than 180°C, and which can be measured using a dynamic rheological analyzer (DMA). It is more preferable that the storage elastic modulus at 30° C. is 1.0×10 ⁸ Pa or more, and the storage elastic modulus at glass transition temperature +30° C. is less than 1.0×10 ⁷ Pa. On the other hand, "non-thermoplastic polyimide" refers to polyimide that does not soften or exhibit adhesive properties even when heated. It means that the storage elastic modulus at 300° C. is 1.0×10 ⁹ Pa or more and the storage elastic modulus at 300° C. is 1.0×10 ⁸ Pa or more.
In the adhesive film of the present invention using such polyimide, it is desirable that the tensile modulus is preferably 0.5 GPa or more, more preferably 1.0 GPa or more.

The adhesive film for build-up substrates of the present invention can contain the polyimide of the present invention in any amount, but it is desirable that it be the main component in the resin component.
As long as it does not impede the purpose of the present invention, optional components may include, for example, known plasticizers, epoxy resins, epoxy resin curing agents, maleimides, activated ester resins, compounds having unsaturated bonds such as resins having a styrene skeleton, etc. Crosslinked (cured) resin components, curing agents, curing accelerators, organic fillers, inorganic fillers such as silicon dioxide, aluminum oxide, magnesium oxide, beryllium oxide, boron nitride, aluminum nitride, silicon nitride, aluminum fluoride, calcium fluoride, etc. An adhesive composition can be prepared by appropriately blending a coupling agent, a metal salt of phosphinic acid, a phosphoric acid ester, a flame retardant such as cyclophosphazene, a pigment, and the like with the polyimide.

The adhesive film for build-up substrates of the present invention can be crosslinked by various methods. By forming a crosslinked structure, the heat resistance of polyimide can be significantly improved. Adhesive polyimide with a crosslinked structure is an application example and is a preferred form. Note that since the Mw varies greatly due to crosslinking, the Mw of the crosslinked polyimide has a value different from the Mw of the adhesive polyimide before crosslinking. When the polyimide has a ketone group, a crosslinked structure can be created by reacting the ketone group with the amino group of an amino compound having at least two primary amino groups as functional groups to form a C=N bond. can be formed. Further, an adhesive composition in which a crosslinking agent is blended with an adhesive polyimide having a ketone group is another application example and is a preferred form. Preferred tetracarboxylic dianhydrides for forming the adhesive polyimide having a ketone group include, for example, 3,3',4,4'-benzophenone tetracarboxylic dianhydride (BTDA), and diamine compounds include: Examples include aromatic diamines such as 4,4'-bis(3-aminophenoxy)benzophenone (BABP) and 1,3-bis[4-(3-aminophenoxy)benzoyl]benzene (BABB). Examples of amino compounds having two primary amino groups as functional groups include dihydrazide compounds, aromatic diamines, aliphatic amines, and the like.

The adhesive film for build-up substrates of the present invention is obtained by molding polyimide into a film shape. A suitable molding method is to dissolve the polyimide and other components in a solvent, apply the resulting resin solution onto a support such as a polyethylene terephthalate (PET) film whose surface has been subjected to a release treatment using a known method, and then dry it. It can be formed into a film by peeling it off from the support.

As described above, the organic solvent used in film molding is preferably a ketone-based solvent (S1) with a boiling point of less than 200°C used in the polymerization reaction and an aromatic hydrocarbon-based solvent (S2) that are used in combination as is. In addition, although not limited thereto, aliphatic hydrocarbon-based solvents such as hexane and heptane, alicyclic hydrocarbon-based solvents such as cyclohexane, methylcyclohexane, and ethylcyclohexane, ethyl acetate, diisopropyl ether, etc. may also be used in combination within the range that does not impair the solubility of polyimide.

The polyimide applied to the adhesive film for build-up boards of the present invention preferably has a dielectric loss tangent (Tan δ) of less than 0.0030, more preferably 0.0025 or less, and even more preferably 0.0020 or less at 10 GHz, as measured by a split post dielectric resonator (SPDR) after 24 hours of humidity conditioning under constant temperature and humidity conditions (normal state) of 23°C and 50% RH, and a relative dielectric constant (ε) of 3.0 or less, preferably 2.7 or less. If the dielectric loss tangent (Tan δ) and relative dielectric constant (ε) exceed the above values, this leads to an increase in dielectric loss when applied to a circuit board, and is likely to cause inconveniences such as loss of electrical signals on the transmission path of high-frequency signals in the GHz range (e.g., 1 to 40 GHz).

The polyimide used in the adhesive film for build-up substrates of the present invention preferably has a coefficient of thermal expansion (CTE) of 150 ppm/°C or less and a glass transition temperature (Tg) of 70°C or more. The CTE is more preferably 100 ppm/°C or less, and even more preferably 80 ppm/°C or less. Tg is more preferably 95°C or higher, still more preferably 120°C or higher. However, as mentioned above, it is desirable to use a thermoplastic polyimide whose glass transition temperature can be clearly confirmed, especially in a temperature range of less than 200°C.

The adhesive film for build-up boards of the present invention can be used by inserting the heat-resistant adhesive film between adherends, such as flexible printed circuit boards, glass fiber-epoxy wiring boards, paper-phenol wiring boards, polyester wiring boards, polyimide wiring boards, BT resin wiring boards, thermosetting polyphenylene ether wiring boards, metals, and resin substrates, and then thermocompressing the film at a temperature of less than 200°C and a pressure of less than 4 MPa, thereby forming an interlayer insulating layer between the adherends.

ＢＡＦＬ：９，９－ビス（４－アミノフェニル）フルオレン

ＢＡＰＰ：２，２’－ビス（４－アミノフェノキシフェニル）プロパン

ＢＴＤＡ：３，３’，４，４’－ベンゾフェノンテトラカルボン酸二無水物

ＢＰＤＡ：３，３’，４，４’－ビフェニルテトラカルボン酸二無水物

Ｎ－１２：ドデカン二酸ジヒドラジド（架橋硬化剤）
ＯＰ９３５：ホスフィン酸のアルミニウム塩（クラリアント社製難燃剤、商品名；Exolit OP935、ジエチルホスフィン酸アルミニウム、リン含有量２３％、平均粒径２μｍ）
フィラー：シリカ粉末（日鉄ケミカル＆マテリアル社製、商品名；ＣＲ１０－２０、球状クリストバライトシリカ粉末、真球状、シリカ含有率；９９．４重量％、クリストバライト結晶相；９３重量％、真比重；２．３３、Ｄ５０；１０．８μｍ、Ｄ９０；１６．４μｍ、Ｄ１００；２４．１μｍ、１０ＧＨｚでの誘電率；３．１６、１０ＧＨｚの誘電正接；０．０００８） Hereinafter, the present invention will be explained in more detail with reference to Examples. In addition, the abbreviations used in the examples indicate the following compounds.
DDA: Aliphatic diamine with 36 carbon atoms (PRIAMINE1075 manufactured by Croda Japan Co., Ltd., amine value: 209 mgKOH/g)
APB: 1,3-bis(3-aminophenoxy)benzene

BAFL: 9,9-bis(4-aminophenyl)fluorene

BAPP: 2,2'-bis(4-aminophenoxyphenyl)propane

BTDA: 3,3',4,4'-benzophenonetetracarboxylic dianhydride

BPDA: 3,3',4,4'-biphenyltetracarboxylic dianhydride

N-12: Dodecanedioic acid dihydrazide (crosslinking curing agent)
OP935: Aluminum salt of phosphinic acid (flame retardant manufactured by Clariant, trade name: Exolit OP935, aluminum diethylphosphinate, phosphorus content 23%, average particle size 2 μm)
Filler: Silica powder (manufactured by Nippon Steel Chemical & Materials Co., Ltd., product name: CR10-20, spherical cristobalite silica powder, true spherical, silica content: 99.4% by weight, cristobalite crystal phase: 93% by weight, true specific gravity: 2 .33, D50: 10.8 μm, D90: 16.4 μm, D100: 24.1 μm, dielectric constant at 10 GHz: 3.16, dielectric loss tangent at 10 GHz: 0.0008)

The evaluation method for each physical property is as follows.
(1) Weight average molecular weight (Mw)
Measurement was performed using a gel permeation chromatograph (HLC-8220GPC manufactured by Tosoh Corporation). Polystyrene was used as a standard substance, and tetrahydrofuran (THF) was used as a developing solvent.
(2) Solubility in organic solvents (viscosity)
Using an E-type viscometer (manufactured by Brookfield, trade name: DV-II+Pro), the polyimide solution was heated at a temperature of 25°C, the rotation speed was set so that the torque was 10 to 90%, and the measurement time was 2 minutes. The viscosity (cP) immediately after polymerization was measured. In the case of gelation, the viscosity could not be measured.
(3) Glass transition temperature (Tg)
A 3 mm × 15 mm test film was subjected to a tensile test in a temperature range of 5 ° C to 300 ° C at a constant heating rate (5 ° C / min) while applying a load of 5.0 g using a thermomechanical analysis (TMA) device. The temperature at which the elongation reached an inflection point when the temperature was increased was defined as the glass transition temperature.
(4) Coefficient of thermal expansion (CTE)
A 3 mm × 15 mm test film was subjected to a tensile test in a temperature range of 5 ° C to 300 ° C at a constant heating rate (5 ° C / min) while applying a load of 5.0 g using a thermomechanical analysis (TMA) device. The coefficient of thermal expansion (ppm/K) was measured from the amount of elongation of the test film at temperatures from 10°C to 30°C.
(5) Dielectric properties The dielectric constant (Dk) and dielectric loss tangent (Df) of the test film at a frequency of 10 GHz were measured using a vector network analyzer (E8363C manufactured by Agilent) resonator. The test film used in the measurement was left for 24 hours at a temperature of 23° C. and a humidity of 50%.
(6) Tensile Modulus A test film with a width of 12.7 mm and a length of 127 mm was subjected to a tensile test at 50 mm/min using a tension tester (manufactured by Orientech Co., Ltd., trade name: Tensilon), and the tensile modulus at 25°C was determined. I asked for

Example 1
In a 500 ml separable flask, 37.98 g DDA (0.071 mol), 13.78 g APB (0.047 mol), 38.24 g BTDA (0.119 mol), and 126 g cycloxanone as a solvent and 84 g of toluene was charged and mixed at 40° C. for 1 hour to prepare a polyamic acid solution. This polyamic acid solution was heated to 140°C, heated and stirred for 5 hours, and 58 g of toluene was added to complete imidization. Polyimide solution 1 (solid content 31.9% by weight, Mw 38,116, viscosity 10,954 cP) ) was prepared.
Next, the obtained polyimide solution 1 was used as it was and applied to a release PET film (HY-S05 manufactured by Higashiyama Film Co., Ltd.) without adding any solvent afterward, and dried at 100 to 120°C for 10 minutes to form a film. After curing, the film was peeled off from the release PET film to obtain an adhesive film 1 with a thickness of 25 μm.
Each physical property was measured for the obtained polyimide solution 1 and adhesive film 1, and the results are shown in Table 1.

Examples 2-3
Polyimide solutions and adhesive films were prepared in the same manner as in Example 1 with the compositions shown in Table 1, and the respective physical properties were measured in the same manner. The results are also shown in Table 1.

Comparative examples 1 to 3
Polyimide solutions and adhesive films were prepared in the same manner as in Example 1 with the compositions shown in Table 1, and the respective physical properties were measured in the same manner. The results are also shown in Table 1.

Example 4
1.13g of crosslinking curing agent (N-12) was blended with 100g of polyimide solution 2 (31g as solid content), 7.75g of flame retardant (OP935), and 51.6g of filler (silica powder CR10-20). Then, 126 g of toluene was added, diluted, and stirred to prepare adhesive composition 2a.
Next, the obtained adhesive composition 2a was applied to a release PET film (HY-S05 manufactured by Higashiyama Film Co., Ltd.), dried at 100 to 120°C for 10 minutes to form a film, and then peeled from the release PET film. As a result, a build-up film 4 having a thickness of 25 μm was obtained.
Each physical property of the obtained cured build-up film 4 was measured, and the results are shown in Table 2.

Examples 5 and 6
Adhesive compositions and build-up films were prepared using the compositions shown in Table 2, and their physical properties were measured in the same manner as in Example 4. The results are shown in Table 2.

Comparative example 4
An adhesive composition and a build-up film were prepared in the same manner as in Example 4 with the compositions shown in Table 2, and each physical property was measured in the same manner. The results are shown in Table 2.

Examples 4 to 6 and Comparative Example 4 (Table 2) are examples of forms used as build-up films.
Buildup film C4 obtained in Comparative Example 4 has a low glass transition temperature and a high CTE.
On the other hand, the build-up films 4 to 6 obtained in Examples 4 to 6 exhibited characteristics of achieving both a high glass transition temperature and a low CTE while maintaining low dielectric properties. Therefore, it has heat resistance and dimensional stability that satisfy low dielectric properties and connection reliability between terminals, and is useful as an interlayer insulating film for build-up boards and multilayer boards.

The adhesive film for build-up substrates of the present invention is useful as an insulating material for various electrical and electronic devices such as personal computers and smartphones.

Claims (9)

An adhesive film that is used as an interlayer insulating film of a build-up board and contains an organic solvent-soluble polyimide consisting of an acid dianhydride component and a diamine component,
The diamine component is selected from a long chain aliphatic diamine component having 24 to 48 carbon atoms, a meta-linked aromatic diamine component represented by the following formula (1), and a fluorene skeleton diamine component represented by the following formula (2). 1. An adhesive film for a build-up substrate, comprising as an essential component at least one aromatic diamine component.

In formula (1), X is -O-, -S-, -CO-, -SO-, -SO2-, -COO-, -CH2-, -CH2-O-, -C(CH3)2-, It represents a divalent group selected from -NH- or -CONH-, and m is 0 or 1. In formula (2), l is 0 or 1. In formula (1) and formula (2), each benzene ring may have a substituent, and the substituent is independently a hydroxyl group, a fluorine atom, or a carbon group optionally substituted with a fluorine atom. Examples include 1 to 3 alkyl groups or alkoxy groups. The adhesive film for build-up boards according to claim 1, which contains 30 to 90 mol % of a long-chain aliphatic diamine component having 24 to 48 carbon atoms relative to the total diamine components. The adhesive film for a build-up substrate according to claim 1, which contains 10 to 70 mol% of the meta-position-linked aromatic diamine component represented by the above formula (1) based on the total diamine components. The adhesive film for build-up substrates according to claim 1, which contains 40 to 70 mol % of the fluorene skeleton diamine component represented by the above formula (2) relative to the total diamine components. The adhesive film for a build-up substrate according to claim 1, which contains 50 mol% or more of an acid dianhydride component having a ketone group as an aromatic ring linking group based on the total acid dianhydride components. The adhesive film for build-up substrates according to claim 1, wherein the polyimide is soluble in an organic solvent having a boiling point of less than 200°C. The adhesive film for a build-up substrate according to claim 1, having a coefficient of thermal expansion (CTE) of 150 ppm/°C or less and a glass transition temperature (Tg) of 70°C or more. A polyimide precursor or polyimide used in the adhesive film for a build-up substrate according to claim 1. A laminated film obtained by laminating the adhesive film for a build-up substrate according to claim 1 on a removable support film.