JP7410716B2 - Resin composition and resin film - Google Patents

Description

The present invention relates to a resin composition and a resin film useful as adhesives in circuit boards such as printed wiring boards.

In recent years, as electronic devices have become smaller, lighter, and space-saving, flexible printed circuit boards (FPCs) have become thinner, lighter, more flexible, and have excellent durability even after repeated bending. Demand for circuits is increasing. FPC can be mounted three-dimensionally and with high density even in a limited space, so it can be used, for example, in the wiring of moving parts of electronic devices such as HDDs, DVDs, and mobile phones, as well as parts such as cables and connectors. It is expanding.

In addition to higher density, as the performance of equipment has improved, it is also necessary to support higher frequency transmission signals. In information processing and communications, efforts are being made to increase the transmission frequency in order to transmit and process large amounts of information, and printed circuit board materials are reducing transmission loss due to thinning of the insulating layer and improvement of the dielectric properties of the insulating layer. There is a need for a reduction in In the future, FPCs and adhesives that can handle higher frequencies will be required, and reducing transmission loss will become important. For example, it has been proposed to reduce the thermal expansion coefficient and dielectric constant by blending silica particles into a polyimide resin used as an insulating resin layer of a circuit board (Patent Document 1, Patent Document 2).

By the way, as a technology related to adhesive layers mainly composed of polyimide, a polyimide made from an aliphatic diamine compound derived from dimer acid (dimer fatty acid) etc. and at least two primary amino groups as functional groups are used. It has been proposed to apply a crosslinked polyimide resin obtained by reacting an amino compound having the above with an adhesive layer of a coverlay film (Patent Document 3). Dimer acid is obtained by performing a Diels-Alder reaction using natural fatty acids such as soybean oil fatty acids, tall oil fatty acids, rapeseed oil fatty acids, and purified versions of these fatty acids such as oleic acid, linoleic acid, linolenic acid, and erucic acid as raw materials. It is known that polybasic acid compounds, which are dimerized fatty acids and derived from dimer acids, can be obtained as a composition of raw fatty acids and trimerized or higher fatty acids.

Japanese Patent Application Publication No. 2001-185853 Japanese Patent Application Publication No. 2018-012747 Japanese Patent Application Publication No. 2013-1730

Polyimide made from an aliphatic diamine compound (hereinafter sometimes referred to as "aliphatic polyimide") as proposed in Patent Document 3 has a low dielectric loss tangent, although there is room for improvement in flame retardancy. Furthermore, the crosslinked polyimide resin obtained by crosslinking this is a material that has both heat resistance and adhesive properties. From this, aliphatic polyimide is expected to be a material for high-speed transmission FPCs, whose usage will increase with the spread of 5G communications. On the other hand, since it is expected that the frequency of signals flowing through FPCs will further increase in the future, there is a demand for materials based on aliphatic polyimide that have even better dielectric properties.

Accordingly, an object of the present invention is to provide a resin composition and a resin film that can be used for higher frequencies in electronic devices by further improving the dielectric properties of aliphatic polyimide.

The resin composition of the present invention comprises the following components (A) and (B),
(A) A dimer diamine whose main component is a tetracarboxylic anhydride component and a dimer diamine obtained by replacing the two terminal carboxylic acid groups of a dimer acid with a primary aminomethyl group or an amino group with respect to all diamine components. A nonvolatile organic compound component containing polyamic acid or polyimide obtained by reacting a diamine component containing 40 mol% or more of the composition,
and (B) silica particles,
and the component (B) is within the range of 5 to 60% by weight based on the total of the component (A) (however, polyamic acid is converted to imidized polyimide) and the component (B). be.

In the resin composition of the present invention, the component (B) contains cristobalite crystal phase and quartz with respect to the total area of all peaks derived from SiO ₂ in the range of 2θ = 10° to 90° in the X-ray diffraction analysis spectrum using CuKα rays. The ratio of the total area of peaks derived from the crystal phase may be 20% by weight or more.

The resin composition of the present invention has an average particle diameter D ₅₀ in the range of 6 to 20 μm at which the cumulative value in the frequency distribution curve obtained by volume-based particle size distribution measurement using a laser diffraction scattering method for the component (B) is 50%. It may be within.

In the resin composition of the present invention, the component (A) contains a total of tetracarboxylic anhydrides represented by the following general formulas (1) and/or (2) with respect to all tetracarboxylic anhydride components. It may contain 90 mol% or more.

In the general formula (1), X represents a single bond or a divalent group selected from the following formula, and in the general formula (2), the cyclic moiety represented by Y is a 4-membered ring or a 5-membered ring. , indicates the formation of a cyclic saturated hydrocarbon group selected from a 6-membered ring, a 7-membered ring, or an 8-membered ring.

In the above formula, Z represents -C ₆ H ₄ -, -(CH ₂ )n- or -CH ₂ -CH(-O-C(=O)-CH ₃ )-CH ₂ -, but n is 1 Indicates an integer between ~20.

The resin film of the present invention is a resin film including a polyimide layer, and the polyimide layer is formed from any of the above resin compositions.

The resin film of the present invention may have a thickness in the range of 15 to 100 μm.

In the resin film of the present invention, the component (B) may be in a range of 3 to 41% by volume based on the total of the component (A) and the component (B).

Since the resin composition of the present invention contains the non-volatile organic compound component (A) and the silica particles (B), the resin film formed using this composition has the characteristics specific to aliphatic polyimide. It has excellent dielectric properties and flexibility, and has further improved dielectric properties and flame retardancy by incorporating silica particles. Therefore, the resin composition and resin film of the present invention can be particularly suitably used as circuit board materials such as FPCs, for example, in electronic devices that require high-speed signal transmission.

Embodiments of the present invention will be described below.

[Resin composition]
The resin composition according to one embodiment of the present invention includes the following components (A) and (B),
(A) A dimer diamine whose main component is a tetracarboxylic anhydride component and a dimer diamine obtained by replacing the two terminal carboxylic acid groups of a dimer acid with a primary aminomethyl group or an amino group with respect to all diamine components. A non-volatile organic compound component containing polyamic acid or polyimide obtained by reacting a diamine component containing 40 mol% or more of the composition, and (B) silica particles,
and the component (B) is within the range of 5 to 60% by weight based on the total of the component (A) (however, polyamic acid is converted to imidized polyimide) and the component (B). be. The resin composition may be a varnish (resin solution) containing polyamic acid, or a polyimide solution containing solvent-soluble polyimide.

<(A) component: nonvolatile organic compound component>
The nonvolatile organic compound component (A) refers to the solid content of the resin composition excluding the solvent and inorganic solid content. That is, the nonvolatile organic compound component contains polyamic acid or polyimide, and optionally includes a resin other than polyimide, a crosslinking agent, an organic filler, a plasticizer, a curing accelerator, a coupling agent, an organic pigment, and an organic flame retardant. etc. can be contained. Here, examples of resins other than polyimide include epoxy resins, fluororesins, olefin resins, maleimide resins, and elastomer resins. Examples of the crosslinking agent include amino compounds having at least two primary amino groups as functional groups (amino compounds for forming crosslinks), bismaleimide compounds, acrylic (methacrylic) compounds, styrene compounds, etc., which will be described later. can. Examples of the organic filler include liquid crystal polymer particles, fluorine polymer particles, and olefin polymer particles.

The content of polyamic acid or polyimide in component (A) is preferably 60% by weight or more, more preferably 70% by weight or more, and most preferably 80% by weight or more. If the content of polyamic acid or polyimide in component (A) is less than 60% by weight, the toughness of the polyimide decreases and the film retention when a resin film is formed decreases. In addition, in the case of polyamic acid, the weight ratio shall be calculated in terms of imidized polyimide.

<Polyamic acid or polyimide>
The polyamic acid or polyimide used in this embodiment is a dimer acid in which the two terminal carboxylic acid groups of the dimer acid are substituted with primary aminomethyl groups or amino groups with respect to the tetracarboxylic anhydride component and the total diamine component. A polyamic acid precursor obtained by reacting a diamine component containing 40 mol % or more of a dimer diamine composition containing diamine as a main component, and a polyimide obtained by imidizing this polyamic acid. Since the polyamic acid or polyimide used in this embodiment is an aliphatic polyamic acid or polyimide, it is a thermoplastic polyimide, has high flexibility, and has sufficient toughness even when a large amount of silica particles are added. However, when a resin film is formed, it has a high ability to maintain its shape. In addition, "thermoplastic polyimide" generally refers to a polyimide whose glass transition temperature (Tg) can be clearly confirmed, but in the present invention, it is a polyimide whose glass transition temperature (Tg) can be clearly confirmed. A polyimide having a storage modulus of 1.0×10 ⁸ Pa or more at 300° C. and less than 3.0×10 ⁷ Pa at 300° C. In addition, "non-thermoplastic polyimide" generally refers to polyimide that does not soften or exhibit adhesive properties even when heated, but in the present invention, 30 A polyimide having a storage modulus of 1.0×10 ⁹ Pa or more at 300° C. and a storage modulus of 3.0×10 ⁸ Pa or more at 300° C.

The polyamic acid or polyimide used in this embodiment contains a tetracarboxylic acid residue derived from a raw material tetracarboxylic anhydride and a diamine residue derived from a raw material diamine compound. By reacting the raw materials tetracarboxylic acid anhydride and diamine compound in approximately equimolar amounts, the type and amount of the tetracarboxylic acid residue and diamine residue contained in the polyamic acid or polyimide can be adjusted based on the type and amount of the raw material. The amounts can be roughly matched.

(Tetracarboxylic anhydride component)
For the polyamic acid or polyimide used in this embodiment, tetracarboxylic anhydride, which is generally used for thermoplastic polyimide, can be used as a raw material without any particular restriction. It is preferable that the total content of the tetracarboxylic acid anhydride represented by (1) and/or (2) is 90 mol% or more. In other words, the polyamic acid or polyimide used in this embodiment contains tetracarboxylic acid anhydride represented by the following general formula (1) and/or (2) based on 100 mole parts of all tetracarboxylic acid residues. It is preferable to contain a total of 90 mole parts or more of tetracarboxylic acid residues derived from compounds. A total of 90 mole parts or more of tetracarboxylic acid residues derived from tetracarboxylic anhydrides represented by the following general formulas (1) and/or (2) based on 100 mole parts of tetracarboxylic acid residues. By containing it, it is easy to achieve both flexibility and heat resistance of the polyimide, which is preferable. If the total amount of tetracarboxylic acid residues derived from the tetracarboxylic anhydrides represented by the following general formulas (1) and/or (2) is less than 90 mole parts, the solvent solubility of the polyimide tends to decrease. Become.

In the general formula (1), X represents a single bond or a divalent group selected from the following formula, and in the general formula (2), the cyclic moiety represented by Y is a 4-membered ring or a 5-membered ring. , indicates the formation of a cyclic saturated hydrocarbon group selected from a 6-membered ring, a 7-membered ring, or an 8-membered ring.

In the above formula, Z represents -C ₆ H ₄ -, -(CH ₂ )n- or -CH ₂ -CH(-O-C(=O)-CH ₃ )-CH ₂ -, but n is 1 Indicates an integer between ~20.

Examples of the tetracarboxylic anhydride represented by the above general formula (1) include 3,3',4,4'-biphenyltetracarboxylic dianhydride (BPDA), 3,3',4,4' -Benzophenonetetracarboxylic dianhydride (BTDA), 3,3',4,4'-diphenylsulfonetetracarboxylic dianhydride (DSDA), 4,4'-oxydiphthalic anhydride (ODPA), 4,4 '-(hexafluoroisopropylidene) diphthalic anhydride (6FDA), 2,2-bis[4-(3,4-dicarboxyphenoxy)phenyl]propane dianhydride (BPADA), p-phenylenebis(trimeritide) Examples include acid monoester acid anhydride (TAHQ), ethylene glycol bisanhydrotrimellitate (TMEG), and the like. Among these, 3,3',4,4'-benzophenonetetracarboxylic dianhydride (BTDA) is particularly preferred. When BTDA is used, since the carbonyl group (ketone group) contributes to adhesiveness, it is possible to suppress a decrease in peel strength due to the addition of component (B), silica particles, and improve the adhesiveness of polyimide. In addition, in BTDA, the ketone group present in the molecular skeleton and the amino group of the amino compound for crosslink formation, which will be described later, may react to form a C=N bond, which tends to improve heat resistance. . From this viewpoint, it is preferable to contain 50 moles or more, more preferably 60 moles or more of tetracarboxylic acid residues derived from BTDA per 100 moles of tetracarboxylic acid residues.

Further, as the tetracarboxylic acid anhydride represented by the general formula (2), for example, 1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,2,3,4-cyclopentanetetracarboxylic acid Dianhydride, 1,2,4,5-cyclohexanetetracarboxylic dianhydride, 1,2,4,5-cycloheptanetetracarboxylic dianhydride, 1,2,5,6-cyclooctanetetracarboxylic acid Examples include dianhydrides.

The polyamic acid or polyimide of this embodiment is derived from an acid anhydride other than the tetracarboxylic anhydride represented by the above general formula (1) and general formula (2), within a range that does not impair the effects of the invention. It can contain tetracarboxylic acid residues. Such tetracarboxylic acid residues are not particularly limited, but include, for example, pyromellitic dianhydride, 2,3',3,4'-biphenyltetracarboxylic dianhydride, 2,2',3 , 3'- or 2,3,3',4'-benzophenone tetracarboxylic dianhydride, 2,3',3,4'-diphenyl ether tetracarboxylic dianhydride, bis(2,3-dicarboxyphenyl ) ether dianhydride, 3,3'',4,4''-, 2,3,3'',4''- or 2,2'',3,3''-p-terphenyltetracarboxylic Acid dianhydride, 2,2-bis(2,3- or 3,4-dicarboxyphenyl)-propane dianhydride, bis(2,3- or 3,4-dicarboxyphenyl)methane dianhydride, Bis(2,3- or 3,4-dicarboxyphenyl)sulfone dianhydride, 1,1-bis(2,3- or 3,4-dicarboxyphenyl)ethane dianhydride, 1,2,7, 8-, 1,2,6,7- or 1,2,9,10-phenanthrene-tetracarboxylic dianhydride, 2,3,6,7-anthracenetetracarboxylic dianhydride, 2,2-bis (3,4-dicarboxyphenyl)tetrafluoropropane dianhydride, 1,2,5,6-naphthalenetetracarboxylic dianhydride, 1,4,5,8-naphthalenetetracarboxylic dianhydride, 2, 3,6,7-naphthalenetetracarboxylic dianhydride, 4,8-dimethyl-1,2,3,5,6,7-hexahydronaphthalene-1,2,5,6-tetracarboxylic dianhydride , 2,6- or 2,7-dichloronaphthalene-1,4,5,8-tetracarboxylic dianhydride, 2,3,6,7-(or 1,4,5,8-)tetrachloronaphthalene -1,4,5,8-(or 2,3,6,7-)tetracarboxylic dianhydride, 2,3,8,9-,3,4,9,10-,4,5,10 , 11- or 5,6,11,12-perylene-tetracarboxylic dianhydride, pyrazine-2,3,5,6-tetracarboxylic dianhydride, pyrrolidine-2,3,4,5-tetracarboxylic dianhydride Aromatic tetracarboxylic dianhydrides such as acid dianhydrides, thiophene-2,3,4,5-tetracarboxylic dianhydrides, and 4,4'-bis(2,3-dicarboxyphenoxy)diphenylmethane dianhydrides. Examples include tetracarboxylic acid residues derived from compounds.

(Diamine component)
For the polyamic acid or polyimide used in this embodiment, a diamine component containing 40 mol% or more, more preferably 60 mol% or more of a dimer diamine composition based on the total diamine component is used as a raw material. By containing the dimer diamine composition in the above amount, the dielectric properties of polyimide are improved, and the thermocompression bonding properties are improved by lowering the glass transition temperature (lower Tg) of polyimide, and internal stress is reduced by lowering the elastic modulus. can be alleviated.

(Dimer diamine composition)
The dimer diamine composition contains the following component (a) as a main component, and the amounts of components (b) and (c) are controlled.

(a) dimer diamine;
Dimer diamine (component (a)) is a dimer acid in which the two terminal carboxylic acid groups (-COOH) are substituted with a primary aminomethyl group (-CH ₂ --NH ₂ ) or an amino group (-NH ₂ ). It means a diamine. Dimer acid is a known dibasic acid obtained by intermolecular polymerization reaction of unsaturated fatty acids, and its industrial manufacturing process is almost standardized in the industry. It can be obtained by dimerization using etc. Industrially obtained dimer acids are mainly composed of dibasic acids with 36 carbon atoms obtained by dimerizing unsaturated fatty acids with 18 carbon atoms such as oleic acid, linoleic acid, and linolenic acid. Depending on the degree, it contains arbitrary amounts of monomer acid (18 carbon atoms), trimer acid (54 carbon atoms), and other polymerized fatty acids having 20 to 54 carbon atoms. Further, although double bonds remain after the dimerization reaction, in the present invention, dimer acids also include those whose degree of unsaturation has been reduced by further hydrogenation reaction. Component (a), the dimer diamine, is obtained by substituting the terminal carboxylic acid group of a dibasic acid compound having a carbon number of 18 to 54, preferably 22 to 44, with a primary aminomethyl group or an amino group. It can be defined as the diamine compound obtained.

As a feature of dimer diamine, it is possible to impart properties derived from the skeleton of dimer acid. That is, since dimer diamine is a large aliphatic molecule with a molecular weight of about 560 to 620, it can increase the molar volume of the molecule and relatively reduce the number of polar groups in polyimide. It is thought that such characteristics of the dimer acid type diamine contribute to improving the dielectric properties by reducing the dielectric constant and the dielectric loss tangent while suppressing a decrease in the heat resistance of polyimide. In addition, since it has two freely movable hydrophobic chains with 7 to 9 carbon atoms and two chain-like aliphatic amino groups with a length close to 18 carbon atoms, it not only gives polyimide flexibility, but also Since polyimide can be made to have an asymmetrical chemical structure or a non-planar chemical structure, it is thought that it is possible to lower the dielectric constant of polyimide.

The dimer diamine composition used is one in which the dimer diamine content of component (a) is increased to 96% by weight or more, preferably 97% by weight or more, and more preferably 98% by weight or more by a purification method such as molecular distillation. That's good. By setting the dimer diamine content of component (a) to 96% by weight or more, broadening of the molecular weight distribution of the polyimide can be suppressed. Note that, if technically possible, it is best that all (100% by weight) of the dimer diamine composition be composed of the dimer diamine component (a).

(b) a monoamine compound obtained by substituting the terminal carboxylic acid group of a monobasic acid compound having a carbon number of 10 to 40 with a primary aminomethyl group or an amino group;
The monobasic acid compound having a carbon number of 10 to 40 is a monobasic unsaturated fatty acid having a carbon number of 10 to 20 derived from the raw material of the dimer acid, and a by-product during the production of the dimer acid. It is a mixture of monobasic acid compounds having carbon numbers ranging from 21 to 40. Monoamine compounds are obtained by substituting the terminal carboxylic acid group of these monobasic acid compounds with a primary aminomethyl group or an amino group.

The monoamine compound (b) is a component that suppresses an increase in the molecular weight of polyimide. During the polymerization of polyamic acid or polyimide, the monofunctional amino group of the monoamine compound reacts with the terminal acid anhydride group of the polyamic acid or polyimide, thereby sealing the terminal acid anhydride group and reducing the molecular weight of the polyamic acid or polyimide. Control the increase.

(c) An amine compound obtained by substituting the terminal carboxylic acid group of a polybasic acid compound having a hydrocarbon group in the range of 41 to 80 carbon atoms with a primary aminomethyl group or an amino group (however, the dimer diamine except for);
A polybasic acid compound having a hydrocarbon group having a carbon number of 41 to 80 is mainly composed of a tribasic acid compound having a carbon number of 41 to 80, which is a by-product during the production of dimer acid. It is a polybasic acid compound. Furthermore, it may contain polymerized fatty acids other than dimer acids having 41 to 80 carbon atoms. Amine compounds are obtained by substituting the terminal carboxylic acid group of these polybasic acid compounds with a primary aminomethyl group or an amino group.

The amine compound (c) is a component that promotes an increase in the molecular weight of polyimide. A trifunctional or higher-functional amino group whose main component is a triamine derived from a trimer acid reacts with the terminal acid anhydride group of the polyamic acid or polyimide, rapidly increasing the molecular weight of the polyimide. Furthermore, amine compounds derived from polymerized fatty acids other than dimer acids having 41 to 80 carbon atoms also increase the molecular weight of polyimide and cause gelation of polyamic acid or polyimide.

The above-mentioned dimer diamine composition is used to facilitate confirmation of the peak start, peak top, and peak end of each component of the dimer diamine composition when quantifying each component by measurement using gel permeation chromatography (GPC). A sample of the dimer diamine composition treated with acetic anhydride and pyridine is used, and cyclohexanone is used as an internal standard. Using the sample prepared in this way, each component is quantified by the area percentage of the GPC chromatogram. The peak start and peak end of each component are the minimum values of each peak curve, and based on these, the area percentage of the chromatogram can be calculated.

Furthermore, in the dimer diamine composition used in the present invention, the sum of components (b) and (c) is preferably 4% or less, preferably less than 4%, in area percentage of a chromatogram obtained by GPC measurement. By controlling the total amount of components (b) and (c) to 4% or less, broadening of the molecular weight distribution of polyimide can be suppressed.

Further, the area percentage of the chromatogram of component (b) is preferably 3% or less, more preferably 2% or less, still more preferably 1% or less. By setting it within such a range, it is possible to suppress a decrease in the molecular weight of the polyimide, and it is also possible to widen the range of the molar ratio of the tetracarboxylic anhydride component and the diamine component. Note that component (b) does not need to be included in the dimer diamine composition.

Further, the area percentage of the chromatogram of component (c) is 2% or less, preferably 1.8% or less, more preferably 1.5% or less. By setting it within such a range, it is possible to suppress a rapid increase in the molecular weight of the polyimide, and it is also possible to suppress an increase in the dielectric loss tangent of the resin film over a wide range of frequencies. Note that component (c) may not be included in the dimer diamine composition.

In addition, when the area percentage ratio (b/c) of the chromatograms of components (b) and (c) is 1 or more, the molar ratio of the tetracarboxylic anhydride component and the diamine component (tetracarboxylic anhydride component/ diamine component) is preferably 0.97 or more and less than 1.0, and by setting such a molar ratio, it becomes easier to control the molecular weight of the polyimide.

In addition, when the area percentage ratio (b/c) of the chromatogram of components (b) and (c) is less than 1, the molar ratio of the tetracarboxylic anhydride component and the diamine component (tetracarboxylic anhydride component /diamine component) is preferably 0.97 or more and 1.1 or less, and by setting such a molar ratio, it becomes easier to control the molecular weight of the polyimide.

The dimer diamine composition used in the present invention is preferably purified for the purpose of reducing components other than the dimer diamine component (a). The purification method is not particularly limited, but known methods such as distillation and precipitation purification are suitable. The dimer diamine composition before purification is commercially available, and examples thereof include PRIAMINE 1073 (trade name), PRIAMINE 1074 (trade name), and PRIAMINE 1075 (trade name) manufactured by Croda Japan.

Examples of diamine compounds other than dimer diamine used in polyimide include aromatic diamine compounds and aliphatic diamine compounds. Specific examples thereof include 1,4-diaminobenzene (p-PDA; paraphenylenediamine), 2,2'-dimethyl-4,4'-diaminobiphenyl (m-TB), 2,2'-n- Propyl-4,4'-diaminobiphenyl (m-NPB), 4-aminophenyl-4'-aminobenzoate (APAB), 2,2-bis-[4-(3-aminophenoxy)phenyl]propane, bis[ 4-(3-aminophenoxy)phenyl] sulfone, bis[4-(3-aminophenoxy)biphenyl, bis[1-(3-aminophenoxy)]biphenyl, bis[4-(3-aminophenoxy)phenyl]methane , bis[4-(3-aminophenoxy)phenyl]ether, bis[4-(3-aminophenoxy)]benzophenone, 9,9-bis[4-(3-aminophenoxy)phenyl]fluorene, 2,2- Bis-[4-(4-aminophenoxy)phenyl]hexafluoropropane, 2,2-bis-[4-(3-aminophenoxy)phenyl]hexafluoropropane, 3,3'-dimethyl-4,4'- Diaminobiphenyl, 4,4'-methylenedi-o-toluidine, 4,4'-methylenedi-2,6-xylidine, 4,4'-methylene-2,6-diethylaniline, 3,3'-diaminodiphenylethane, 3,3'-diaminobiphenyl, 3,3'-dimethoxybenzidine, 3,3''-diamino-p-terphenyl, 4,4'-[1,4-phenylenebis(1-methylethylidene)]bisaniline, 4,4'-[1,3-phenylenebis(1-methylethylidene)]bisaniline, bis(p-aminocyclohexyl)methane, bis(p-β-amino-t-butylphenyl)ether, bis(p-β) -Methyl-δ-aminopentyl)benzene, p-bis(2-methyl-4-aminopentyl)benzene, p-bis(1,1-dimethyl-5-aminopentyl)benzene, 1,5-diaminonaphthalene, 2 ,6-diaminonaphthalene, 2,4-bis(β-amino-t-butyl)toluene, 2,4-diaminotoluene, m-xylene-2,5-diamine, p-xylene-2,5-diamine, m -xylylenediamine, p-xylylenediamine, 2,6-diaminopyridine, 2,5-diaminopyridine, 2,5-diamino-1,3,4-oxadiazole, piperazine, 2'-methoxy-4, 4'-Diaminobenzanilide, 4,4'-diaminobenzanilide, 1,3-bis[2-(4-aminophenyl)-2-propyl]benzene, 6-amino-2-(4-aminophenoxy)benzo Examples include diamine compounds such as oxazole and 1,3-bis(3-aminophenoxy)benzene.

Polyimide can be produced by reacting the above-mentioned tetracarboxylic acid anhydride component and diamine component in a solvent to generate a polyamic acid, and then ring-closing the polyamic acid by heating. For example, a polyimide precursor can be obtained by dissolving approximately equimolar amounts of a tetracarboxylic acid anhydride component and a diamine component in an organic solvent, stirring at a temperature within the range of 0 to 100°C for 30 minutes to 24 hours, and causing a polymerization reaction. A polyamic acid is obtained. In the reaction, the reaction components are dissolved in the organic solvent so that the amount of the precursor to be produced is within the range of 5 to 50% by weight, preferably within the range of 10 to 40% by weight. Examples of organic solvents used in the polymerization reaction include N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAc), N,N-diethylacetamide, N-methyl-2-pyrrolidone (NMP), 2 -Butanone, dimethyl sulfoxide (DMSO), hexamethylphosphoramide, N-methylcaprolactam, dimethyl sulfate, cyclohexanone, methylcyclohexane, dioxane, tetrahydrofuran, diglyme, triglyme, methanol, ethanol, benzyl alcohol, cresol, and the like. Two or more of these solvents can be used in combination, and aromatic hydrocarbons such as xylene and toluene can also be used in combination. Further, the amount of such an organic solvent to be used is not particularly limited, but it should be adjusted to an amount such that the concentration of the polyamic acid solution obtained by the polymerization reaction is about 5 to 50% by weight. is preferred.

It is usually advantageous to use the synthesized polyamic acid as a reaction solvent solution, but it can be concentrated, diluted, or replaced with another organic solvent if necessary. In addition, polyamic acids generally have excellent solvent solubility and are therefore advantageously used. Preferably, the viscosity of the polyamic acid solution is within the range of 500 cps to 100,000 cps. Outside this range, defects such as uneven thickness and streaks are likely to occur in the film during coating operations using a coater or the like.

The method of imidizing polyamic acid to form polyimide is not particularly limited, and for example, heat treatment such as heating in the above solvent at a temperature in the range of 80 to 400 ° C. for 1 to 24 hours is preferably employed. be done. Further, the temperature may be heated under constant temperature conditions, or the temperature may be changed during the process.

In the polyimide of this embodiment, by selecting the types of the above-mentioned tetracarboxylic anhydride component and diamine component and the respective molar ratios when applying two or more types of tetracarboxylic anhydride components or diamine components, Dielectric properties, coefficient of thermal expansion, tensile modulus, glass transition temperature, etc. can be controlled. Furthermore, in the case where the polyimide of this embodiment has a plurality of polyimide structural units, they may exist as blocks or randomly, but it is preferable that they exist randomly.

The weight average molecular weight of the polyimide is preferably within the range of, for example, 10,000 to 200,000, and within this range, the weight average molecular weight of the polyimide can be easily controlled. Further, when applied as an adhesive for FPC, for example, the weight average molecular weight of the polyimide is more preferably within the range of 20,000 to 150,000, and even more preferably within the range of 40,000 to 150,000. When applied as an adhesive for FPC, if the weight average molecular weight of polyimide is less than 20,000, flow resistance tends to deteriorate. On the other hand, when the weight average molecular weight of polyimide exceeds 150,000, the viscosity increases excessively and it becomes insoluble in solvents, which tends to cause defects such as uneven thickness of the adhesive layer and streaks during coating work. Become.

The imide group concentration of the polyimide of this embodiment is preferably 22% by weight or less, more preferably 20% by weight or less. Here, "imide group concentration" means the value obtained by dividing the molecular weight of the imide group (-(CO) ₂ -N-) in polyimide by the molecular weight of the entire polyimide structure. When the imide group concentration exceeds 22% by weight, the molecular weight of the resin itself decreases, and the low hygroscopicity deteriorates due to the increase in polar groups, and the Tg and elastic modulus increase.

The polyimide of this embodiment most preferably has a completely imidized structure. However, a part of the polyimide may be an amic acid. The imidization rate was determined to be around 1015 cm ^-1 by measuring the infrared absorption spectrum of the polyimide thin film by the single reflection ATR method using a Fourier transform infrared spectrophotometer (commercial product: JASCO Corporation FT/IR620). It can be calculated from the absorbance of C=O stretching derived from the imide group at 1780 cm ^-1 using the benzene ring absorber as a reference.

<Crosslink formation>
When the polyimide in component (A) has a ketone group, an amino compound having the ketone group and at least two primary amino groups as functional groups (hereinafter referred to as "crosslinking amino compound") A crosslinked structure can be formed by reacting the amino groups of (a) to form a C=N bond. By forming a crosslinked structure, the heat resistance of the thermoplastic polyimide forming the adhesive layer can be improved. Preferred tetracarboxylic anhydrides for forming a thermoplastic polyimide having a ketone group include, for example, 3,3',4,4'-benzophenone tetracarboxylic dianhydride (BTDA), and examples of diamine compounds include, for example. , 4,4'-bis(3-aminophenoxy)benzophenone (BABP), and 1,3-bis[4-(3-aminophenoxy)benzoyl]benzene (BABB).

For the purpose of forming a crosslinked structure, the resin composition of the present invention preferably contains BTDA residues derived from BTDA in an amount of preferably 50 mol% or more, more preferably 60 mol%, based on all tetracarboxylic acid residues. % or more of the polyimide in component (A) and the amino compound for crosslinking formation. In addition, in the present invention, "BTDA residue" means a tetravalent group derived from BTDA.

Examples of the amino compound for forming crosslinks include (I) dihydrazide compounds, (II) aromatic diamines, and (III) aliphatic amines. Among these, dihydrazide compounds are preferred. Aliphatic amines other than dihydrazide compounds tend to form crosslinked structures even at room temperature, and there is a concern about the storage stability of the varnish. On the other hand, aromatic diamines require high temperatures to form crosslinked structures. In this way, when a dihydrazide compound is used, both the storage stability of the varnish and the shortening of the curing time can be achieved. Examples of dihydrazide compounds include oxalic acid dihydrazide, malonic acid dihydrazide, succinic acid dihydrazide, glutaric acid dihydrazide, adipic acid dihydrazide, pimelic acid dihydrazide, suberic acid dihydrazide, azelaic acid dihydrazide, sebacic acid dihydrazide, dodecanedioic acid dihydrazide, and maleic acid. Dihydrazide, fumaric acid dihydrazide, diglycolic acid dihydrazide, tartaric acid dihydrazide, malic acid dihydrazide, phthalic acid dihydrazide, isophthalic acid dihydrazide, terephthalic acid dihydrazide, 2,6-naphthoedioic acid dihydrazide, 4,4-bisbenzene dihydrazide, 1,4 -Dihydrazide compounds such as naphthoic acid dihydrazide, 2,6-pyridinedioic acid dihydrazide, and itaconic acid dihydrazide are preferred. The above dihydrazide compounds may be used alone or in combination of two or more.

In addition, amino compounds such as (I) dihydrazide compounds, (II) aromatic diamines, and (III) aliphatic amines are, for example, combinations of (I) and (II), combinations of (I) and (III), It is also possible to use a combination of two or more types across categories, such as the combination of (I), (II), and (III).

In addition, from the viewpoint of making the network structure formed by crosslinking with the crosslinking amino compound denser, the crosslinking amino compound used in the present invention should have a molecular weight (if the crosslinking amino compound is an oligomer) (weight average molecular weight) is preferably 5,000 or less, more preferably 90 to 2,000, still more preferably 100 to 1,500. Among these, crosslinking amino compounds having a molecular weight of 100 to 1,000 are particularly preferred. When the molecular weight of the crosslinking amino compound is less than 90, one amino group of the crosslinking amino compound only forms a C=N bond with the ketone group of the polyimide resin, and the periphery of the remaining amino group becomes sterically Due to the increased bulk, the remaining amino groups tend to be less likely to form C=N bonds.

When forming a crosslink between the ketone group in the polyimide in component (A) and the amino compound for crosslinking, add the above amino compound for crosslinking to a resin solution containing the component (A), and add the ketone group in the polyimide to the resin solution containing the component (A). and the primary amino group of the crosslinking amino compound are subjected to a condensation reaction. This condensation reaction causes the resin solution to harden into a cured product. In this case, the amount of the crosslinking amino compound added is a total of 0.004 mol to 1.5 mol, preferably 0.005 mol to 1.2 mol, of primary amino groups per 1 mol of ketone group. The amount can be more preferably 0.03 mol to 0.9 mol, most preferably 0.04 mol to 0.6 mol. If the amount of the crosslinking amino compound added is such that the total amount of primary amino groups is less than 0.004 mol per mol of the ketone group, the crosslinking by the crosslinking amino compound will not be sufficient, so the Heat resistance tends to be difficult to develop, and if the amount of crosslinking amino compound added exceeds 1.5 mol, unreacted crosslinking amino compound acts as a thermoplastic agent, reducing the heat resistance of the adhesive layer. There is a tendency to

The conditions for the condensation reaction to form a crosslink are such that the ketone group in the polyimide in component (A) reacts with the primary amino group of the above amino compound for crosslinking to form an imine bond (C=N bond). If so, there are no particular restrictions. The temperature of the heating condensation is determined for reasons such as releasing water generated by condensation out of the system, or simplifying the condensation process when the heating condensation reaction is performed subsequent to the synthesis of the polyimide in component (A). For example, the temperature is preferably within the range of 120 to 220°C, and more preferably within the range of 140 to 200°C. The reaction time is preferably about 30 minutes to 24 hours. The end point of the reaction can be determined, for example, by measuring the infrared absorption spectrum using a Fourier transform infrared spectrophotometer (commercial product: JASCO Corporation FT/IR620), and determining the absorption originating from the ketone group in the polyimide resin around 1670 cm ^-1 . This can be confirmed by the decrease or disappearance of the peak and the appearance of an absorption peak derived from the imine group around 1635 cm ^-1 .

The heating condensation of the ketone group of the polyimide in component (A) and the primary amino group of the above-mentioned amino compound for crosslinking is carried out by, for example,
(1) Following the synthesis (imidization) of the polyimide in component (A), a method of adding an amino compound for crosslinking and heating;
(2) An excess amount of an amino compound is charged in advance as a diamine component, and following the synthesis (imidization) of the polyimide in component (A), the remaining amino compound not involved in imidization or amidation is added to the amino compound for crosslinking. A method of using it as a compound and heating it together with polyimide, or
(3) After processing the polyimide composition in component (A) to which the above-mentioned crosslinking amino compound is added into a predetermined shape (for example, after applying it to an arbitrary base material or forming it into a film shape). This can be done by a heating method, etc.

In order to impart heat resistance to the polyimide in the component (A), the formation of an imine bond has been described as the formation of a crosslinked structure, but the invention is not limited thereto. It is also possible to blend and cure an epoxy resin, an epoxy resin curing agent, a compound having an unsaturated bond such as maleimide, an activated ester resin, or a resin having a styrene skeleton.

<(B) component: silica particles>
As the silica particles of component (B), both crystalline silica particles and amorphous silica particles can be used, but it is preferable that crystalline silica particles are included. By blending the silica particles of component (B), the dielectric loss tangent when a resin film is formed can be lowered. From the viewpoint of achieving a low dielectric loss tangent when forming a resin film, it is particularly preferable to use silica particles having a cristobalite crystal phase as the crystalline silica particles. Silica particles having a cristobalite crystal phase have very superior dielectric properties compared to general silica particles (for example, silica particles containing 90% by weight or more of a cristobalite crystal phase have a dielectric loss tangent of 0.000 at 20 GHz). 0001), which can greatly contribute to lowering the dielectric loss tangent of the resin film.

Moreover, it is preferable to use spherical silica particles as the silica particles. Spherical silica particles are silica particles that are nearly perfectly spherical in shape, and the ratio of the average major axis to the average minor axis is 1 or close to 1.

Furthermore, since silica does not thermally decompose at normal combustion temperatures, flame retardancy can be improved by adding silica particles as component (B).

In addition, from the viewpoint of achieving a low dielectric loss tangent when forming a resin film, the silica particles used as a whole contain all of the total amount derived from SiO ₂ in the range of 2θ = 10° to 90° in the X-ray diffraction analysis spectrum using CuKα rays. The ratio of the total area of the peaks derived from the cristobalite crystal phase and the quartz crystal phase to the total area of the peaks is preferably 20% by weight or more, more preferably 40% by weight or more, and desirably 80% by weight or more. By increasing the proportion of cristobalite crystal phase and/or quartz crystal phase in the entire silica particles, it is possible to further reduce the dielectric loss tangent of polyimide. If the area ratio of the peaks derived from the cristobalite crystal phase and the quartz crystal phase in the entire silica particles is less than 20% by weight, the effect of improving dielectric properties becomes unclear. In addition, if the peak of interest in the X-ray diffraction analysis spectrum is difficult to separate from a broad amorphous peak or overlaps with another crystalline phase peak, various known analysis methods such as internal standard method or PONKCS may be used. The law, etc. can be used.

The average particle diameter D ₅₀ of the silica particles is preferably within the range of 6 to 20 μm, more preferably within the range of 8 to 15 μm. Here, the average particle diameter D ₅₀ is a value at which the cumulative value in a frequency distribution curve obtained by volume-based particle size distribution measurement using a laser diffraction scattering method is 50%. If the average particle diameter _D50 is within this range, the dielectric properties can be effectively improved, and when a resin film is formed with the resin composition, the surface smoothness will not be deteriorated, and a low dielectric film with a good appearance can be obtained. can get. When the average particle diameter D ₅₀ is below the above range, the specific surface area of the silica particles increases, and the adsorbed water and polar groups on the surface of the silica particles may affect the dielectric properties. If the average particle diameter _D50 exceeds the above range, it may appear as irregularities on the surface of the resin film, which may deteriorate the smoothness of the film surface.

Further, it is preferable that 90% by weight or more of the silica particles having a particle diameter of 3 μm or more have a circularity of 0.7 or more, more preferably 0.9 or more. The circularity of a silica particle can be determined by an image analysis method, assuming a circle having the same projected area as the photographed particle, and determining the ratio of the circumference of the circle to the circumference of the particle. If the circularity is less than 0.7, the surface area will increase, which may adversely affect dielectric properties, and furthermore, the viscosity will increase significantly when blended into a resin solution, making it difficult to handle. Also, the sphericity determined three-dimensionally is preferably a value that substantially corresponds to the value of the circularity.

Moreover, it is preferable that the true specific gravity of the silica particles is 2.3 or more. A true specific gravity of less than 2.3 suggests that the degree of crystallinity of the silica particles is low, and the effect of improving dielectric properties becomes small.

As the silica particles, commercially available products can be appropriately selected and used. For example, spherical cristobalite silica powder (manufactured by Nippon Steel Chemical & Materials, trade name: CR10-20), spherical amorphous silica powder (manufactured by Nippon Steel Chemical & Materials, trade name: SC70-2), etc. can be preferably used. . Furthermore, two or more different types of silica particles may be used in combination as the silica particles.

<Blend amount>
The weight ratio of component (B) to the total of components (A) and (B) in the resin composition of the present invention is within the range of 5 to 60% by weight. Here, in the case of polyamic acid, the weight ratio is calculated in terms of polyimide (the same applies hereinafter). If the weight ratio of component (B) to the total of components (A) and (B) is less than 5% by weight, the effect of improving dielectric properties and flame retardance may be insufficient; if it exceeds 60% by weight, Formation of the polyimide may become difficult and the resulting polyimide film may become brittle. By controlling the blending amount of component (B) within the above range, dielectric properties and flame retardance can be improved.
In addition, when the content of component (B) is within the range of 5 to 20% by weight based on the total of components (A) and (B), 2θ of the X-ray diffraction analysis spectrum using CuKα rays is 10° to 90°. It is preferable to blend the crystalline silica particles so that the total area of the peaks derived from the cristobalite crystal phase and the quartz crystal phase with respect to the total area of all peaks derived from SiO ₂ in the range of 40% by weight or more is ( If the content of component B) exceeds 20% by weight based on the total of components (A) and (B), the crystallinity should be adjusted so that the peak area derived from the cristobalite crystal phase and the quartz crystal phase is 30% by weight or more. It is preferable to incorporate silica.

In addition, from the viewpoint of increasing adhesive strength to metal layers such as copper foil when forming a resin film, the volume ratio of component (B) to the total of components (A) and (B) is in the range of 3 to 41%. It is preferably within the range of 10 to 35%, and more preferably within the range of 10 to 35%. The volume ratio can be determined by calculation from the density and weight ratio of component (A) and component (B) to be blended, or by cross-sectional observation using a scanning electron microscope.

<Optional ingredients>
The resin composition of this embodiment can contain an organic solvent. Examples of organic solvents include N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAc), N,N-diethylacetamide, N-methyl-2-pyrrolidone (NMP), 2-butanone, dimethyl Examples include sulfoxide (DMSO), hexamethylphosphoramide, N-methylcaprolactam, dimethyl sulfate, cyclohexanone, dioxane, tetrahydrofuran, diglyme, triglyme, and cresol. Two or more of these solvents can be used in combination, and aromatic hydrocarbons such as xylene and toluene can also be used in combination. The content of the organic solvent is not particularly limited, but it is preferable to adjust the amount so that the concentration of polyamic acid or polyimide is about 5 to 30% by weight.

The resin composition of the present invention may further contain optional components such as inorganic fillers other than silica, inorganic pigments, solvents, and inorganic flame retardants, if necessary. Examples of inorganic fillers other than silica particles include aluminum oxide, magnesium oxide, beryllium oxide, boron nitride, aluminum nitride, silicon nitride, aluminum fluoride, and calcium fluoride.

<Viscosity>
The viscosity of the resin composition is preferably within the range of 3,000 cps to 100,000 cps, for example, 5,000 cps to 100,000 cps, as a viscosity range that improves handling properties when applying the resin composition and facilitates forming a coating film of uniform thickness. More preferably, it is within the range of 50,000 cps. If the viscosity is outside the above range, defects such as uneven thickness and streaks are likely to occur in the film during coating with a coater or the like.

<Preparation of resin composition>
The resin composition of the present invention can be prepared, for example, by creating a solution of component (A) using an arbitrary solvent, adding component (B) thereto, and mixing uniformly.
For example, silica particles may be directly blended into a polyamic acid or polyimide resin solution. Alternatively, considering the dispersibility of silica particles, after blending silica particles in advance into a reaction solvent containing one of the acid dianhydride component and diamine component, which are raw materials for polyamic acid, add the other raw material while stirring. may be added to advance the polymerization.
Note that a portion of component (A) (for example, an amino compound for forming crosslinks) may be blended with component (B) at the same time or after component (B) is added.
In either method, the entire amount of silica particles may be added at once, or may be added little by little over several times. Further, the raw materials may be added all at once, or may be mixed little by little in several batches.

When the resin composition of the present invention is used to form an adhesive layer, it has excellent flexibility and thermoplasticity, as well as excellent dielectric properties and flame retardancy. Therefore, the resin composition of the present invention has favorable properties as an adhesive for coverlay films that protect wiring portions of FPCs, rigid-flex circuit boards, etc., for example.

[Resin film]
The resin film of this embodiment is a resin film including a polyimide layer, and the polyimide layer is formed into a film using the solid content (the remainder after removing the solvent) of the resin composition as a main component. In addition to flexibility and adhesiveness, the resin film of the present invention has excellent high frequency properties and flame retardancy, so it can be used as an adhesive for coverlay films that protect wiring parts of FPCs, rigid/flex circuit boards, etc. It can be preferably used for applications such as agent layers and bonding sheets for multilayer FPCs.

The resin film of this embodiment is not particularly limited as long as it is an insulating resin film containing a polyimide layer formed from the above resin composition, and may be a film (sheet) made of an insulating resin. The insulating resin film may be laminated on a base material such as a copper foil, a glass plate, a resin sheet such as a polyimide film, a polyamide film, or a polyester film.

<Relative dielectric constant>
In order to ensure impedance consistency when used on a circuit board such as an FPC, and to reduce electrical signal loss, the resin film of this embodiment is manufactured under constant temperature and humidity conditions of 23°C and 50% RH. The relative dielectric constant (ε ₁ ) at 20 GHz after 24 hours of humidity conditioning is preferably 3.2 or less, more preferably 3.0 or less. If the relative dielectric constant exceeds 3.2, problems such as electrical signal loss on a high frequency signal transmission path are likely to occur when used in a circuit board such as an FPC.

<Dielectric loss tangent>
Furthermore, in order to reduce the loss of electrical signals when used for circuit boards such as FPCs, the resin film of this embodiment is used after being humidified for 24 hours under constant temperature and humidity conditions of 23° C. and 50% RH. The dielectric loss tangent (Tan δ ₁ ) at 20 GHz is preferably less than 0.005, more preferably 0.004 or less, and most preferably 0.002 or less. If the dielectric loss tangent is 0.005 or more, when used in a circuit board such as an FPC, for example, problems such as electrical signal loss on a high frequency signal transmission path are likely to occur.

<Glass transition temperature>
The resin film of this embodiment preferably has a glass transition temperature (Tg) of 250°C or less, more preferably in the range of 40°C or more and 200°C or less. When the Tg of the resin film is 250° C. or lower, thermocompression bonding at low temperatures is possible, so internal stress generated during lamination can be alleviated and dimensional changes after circuit processing can be suppressed. If the Tg of the resin film exceeds 250° C., the adhesion temperature will become high, which may impair the dimensional stability after circuit processing.

<Thickness>
The thickness of the resin film of this embodiment is preferably within the range of, for example, 15 to 100 μm, and more preferably within the range of 20 to 50 μm. If the thickness of the resin film is less than 15 μm, there is a risk of problems such as wrinkles during transportation during the production of the resin film, etc. On the other hand, if the thickness of the resin film exceeds 100 μm, there is a risk of decreased productivity of the resin film. There is.
In addition, when the thickness of the resin film is within the range of 15 μm to 20 μm, in order to suppress unevenness on the surface of the resin film and maintain the smoothness of the film surface, the average particle size of the silica particles of component (B) is It is preferable to use a material having a _D50 of 9 to 12 μm.

Examples are shown below to explain the features of the present invention more specifically. However, the scope of the present invention is not limited to the examples. In addition, in the following examples, various measurements and evaluations are as follows unless otherwise specified.

[Method of measuring amine value]
Approximately 2 g of the dimer diamine composition was weighed into a 200-250 mL Erlenmeyer flask, and using phenolphthalein as an indicator, 0.1 mol/L ethanolic potassium hydroxide solution was added dropwise until the solution took on a pale pink color. , dissolved in approximately 100 mL of neutralized butanol. Add 3 to 7 drops of phenolphthalein solution there, and titrate with 0.1 mol/L ethanolic potassium hydroxide solution while stirring until the sample solution turns light pink. Add 5 drops of bromophenol blue solution there, and titrate with 0.2 mol/L hydrochloric acid/isopropanol solution while stirring until the sample solution turns yellow.
The amine value is calculated using the following formula (1).
Amine value={(V ₂ ×C ₂ )−(V ₁ ×C ₁ )}×M _KOH /m (1)
Here, the amine value is a value expressed in mg-KOH/g, and M _KOH is the molecular weight of potassium hydroxide, 56.1. In addition, V and C are the volume and concentration of the solution used for titration, respectively, and the subscripts 1 and 2 are 0.1 mol/L ethanolic potassium hydroxide solution and 0.2 mol/L hydrochloric acid/isopropanol solution, respectively. represents. Furthermore, m is the sample weight in grams.

[Measurement of weight average molecular weight (Mw) of polyimide]
The weight average molecular weight was measured using a gel permeation chromatograph (manufactured by Tosoh Corporation, using HLC-8220GPC). Polystyrene was used as a standard substance, and tetrahydrofuran was used as a developing solvent.

[Calculation of area percent of GPC and chromatogram]
For GPC, a 100 mg solution of 20 mg of the dimer diamine composition pretreated with 200 μL of acetic anhydride, 200 μL of pyridine, and 2 mL of THF (tetrahydrofuran) was diluted with 10 mL of THF (containing 1000 ppm of cyclohexanone), and the sample was Prepared. The prepared sample was injected using HLC-8220GPC manufactured by Tosoh Corporation, column: TSK-gel G2000HXL, G1000HXL, G1000HXL, flow rate: 1 mL/min, column (oven) temperature: 40°C, injection volume: 50 μL. Measured under the following conditions. In addition, cyclohexanone was treated as a standard substance for correction of outflow time.

At this time, adjust so that the peak top of the main peak of cyclohexanone is at a retention time of 27 minutes to 31 minutes, and the peak end is 2 minutes from the peak start of the main peak of cyclohexanone, and remove the peak of cyclohexanone. Each component (a) to (c);
(a) Component represented by the main peak;
(b) A component represented by a GPC peak detected at a time later than the minimum value of the main peak at a time when the retention time is slow;
(c) A component represented by a GPC peak detected at an earlier time based on the minimum value on the time side where the retention time of the main peak is earlier;
was detected.

[Evaluation of dielectric properties]
<Silica particles>
A vector network analyzer (manufactured by Keysight Technologies, trade name: Vector Network Analyzer E8363C) and a dielectric constant measurement device manufactured by Kanto Denshi Application Development Co., Ltd. using the cavity resonator perturbation method were used, and the dielectric constant measurement mode was set to TM020. The dielectric constant (ε1) and dielectric loss tangent (Tan δ1) of the silica particles were measured at a frequency of 10 GHz. The silica particles were in powder form and were filled into a sample tube (inner diameter: 1.68 mm, outer diameter: 2.28 mm, height: 8 cm) and measured.
<Resin film>
Adhesive pressed using a vector network analyzer (manufactured by Keysight Technologies, product name: Vector Network Analyzer E8363C) and a split post dielectric resonator (SPDR) at a temperature of 160°C, a pressure of 3.5 MPa, and a time of 60 minutes. After the sheet was left for 24 hours at a temperature of 23° C. and a humidity of 50%, the dielectric constant and dielectric loss tangent at a frequency of 20 GHz were measured.

[Measurement of particle size]
Using a laser diffraction particle size distribution analyzer (manufactured by Malvern Co., Ltd., trade name: Master Sizer 3000), the particle size was measured using a laser diffraction/scattering measurement method using water as a dispersion medium and a particle refractive index of 1.54. Measurements were taken.

[Measurement of true specific gravity]
The true specific gravity was measured by the pycnometer method (liquid phase displacement method) using a continuous automatic powder true density measuring device (manufactured by Seishin Enterprise Co., Ltd., trade name: AUTO TRUE DENSERMAT-7000).

[Measurement of cristobalite crystal phase]
All diffraction patterns (peak _position , peak width and peak intensity), the total area of all peaks originating from SiO ₂ is calculated. Next, the peak positions originating from the cristobalite crystal phase were identified, the total area of all the peaks of the cristobalite crystal phase was calculated, and the ratio (wt%) of all the peaks originating from SiO ₂ to the total area was determined. Note that for the attribution of each peak, reference was made to the database of the International Center for Diffraction Data (ICDD).

[Measurement of tensile modulus and maximum elongation]
A test piece (width: 12.7 mm, length: 127 mm) was subjected to a tensile test at 50 mm/min using a tension tester (Tensilon manufactured by Orientec Co., Ltd.), and the tensile modulus and maximum elongation at 25° C. were determined.

[Measurement of glass transition temperature (Tg)]
The adhesive sheet pressed under the conditions of temperature: 160°C, pressure: 3.5 MPa, and time: 60 minutes was cut into test pieces with a size of 5 mm x 20 mm. The measurement was carried out using a 300° C. (trade name: E4000F) from 30° C. to 300° C. at a heating rate of 4° C./min and a frequency of 11 Hz, and the temperature at which the change in elastic modulus (tan δ) was maximum was defined as the glass transition temperature.

[Evaluation of film retention]
Film retention was evaluated using the following procedure. The adhesive sheet was cut into a test piece with a width of 20 mm and a length of 20 mm, which was folded diagonally so as to form a crease, and then opened and the state of the film was observed. At this time, a specimen with no cracks even after being creased and opened was rated as "good", and a specimen with even some cracks was rated as "unacceptable".

[Solder heat resistance test (drying)]
One side of the copper foil of a double-sided copper-clad laminate (manufactured by Nippon Steel Chemical & Materials Co., Ltd., product name: Espanex MB12-25-12UEG) is removed by etching, and the other copper foil is processed to create a wiring width/ A printed circuit board on which a circuit with a wiring spacing (L/S) of 1 mm/1 mm was formed was prepared. After placing an adhesive sheet on the wiring of the printed circuit board and laminating a polyimide film (manufactured by DuPont-Toray Co., Ltd., product name: Kapton 50EN-S) on the opposite side of the adhesive sheet to the side that contacts the printed circuit board, Pressing was carried out under the conditions of temperature: 160°C, pressure: 3.5 MPa, and time: 60 minutes. After drying this test piece with copper foil at 105°C, it was immersed in a solder bath set at each evaluation temperature for 10 seconds, and the adhesion state was observed to check for defects such as foaming, blistering, and peeling. did. Heat resistance is expressed as the upper limit temperature at which no defects occur; for example, "320°C" means that no defects are observed when evaluated in a 320°C solder bath.

[Solder heat resistance test (moisture absorption)]
The copper foil on one side of a double-sided copper-clad laminate (manufactured by Nippon Steel Chemical & Materials Co., Ltd., product name: Espanex MB12-25-12UEG) is removed by etching, and the copper foil on the other side is processed into circuits to increase the wiring width/ A printed circuit board on which a circuit with a wiring spacing (L/S) of 1 mm/1 mm was formed was prepared. After placing an adhesive sheet on the wiring of the printed circuit board and laminating a polyimide film (manufactured by DuPont-Toray Co., Ltd., product name: Kapton 50EN-S) on the opposite side of the adhesive sheet to the side that contacts the printed circuit board, Pressing was carried out under the conditions of temperature: 160°C, pressure: 3.5 MPa, and time: 60 minutes. This test piece with copper foil was left at 40°C and relative humidity: 80% for 72 hours, then immersed in a solder bath set at each evaluation temperature for 10 seconds, and the adhesion state was observed. The presence or absence of defects such as peeling was confirmed. Heat resistance is expressed as the upper limit temperature at which no defects occur; for example, "260°C" means that no defects are observed when evaluated in a solder bath at 260°C.

[Measurement of peel strength]
Copper sample obtained by cutting a double-sided copper-clad laminate (manufactured by Nippon Steel Chemical & Materials Co., Ltd., product name: Espanex MB12-25-12UEG) into a piece with a width of 50 mm and a length of 100 mm, and then removing the copper foil on one side by etching. An adhesive sheet was placed on the foil side, and a polyimide film (manufactured by DuPont-Toray Co., Ltd., trade name: Kapton 50EN-S) was further laminated on the adhesive sheet, temperature: 160°C, pressure: 3.5 MPa, Pressing time: 60 minutes. The adhesive layer was obtained by cutting the laminate into a test piece with a width of 5 mm and pulling it in the 90° direction of the test piece at a speed of 50 mm/min using a tensile testing machine (manufactured by Toyo Seiki Seisakusho, product name: Strograph VE). and the peel strength of the copper foil was measured.

[Flame retardancy evaluation method]
Polyimide films (trade name: Kapton 50EN-S, manufactured by DuPont-Toray Co., Ltd.) were laminated on both sides of the adhesive sheet, and pressed at a temperature of 160° C., a pressure of 3.5 MPa, and a time of 60 minutes. A sample was cut to 200 ± 5 mm x 50 ± 1 mm, rolled into a cylinder shape with a diameter of approximately 12.7 mm and a length of 200 ± 5 mm, and a test piece compliant with the UL94VTM standard was prepared and a combustion test was conducted. Cases that passed the criteria were considered "good". If the test passed the VTM-1 criteria, it was marked as "passable," and if it did not pass the VTM-1 criteria, it was marked as "unsatisfactory."

The abbreviations used in this example represent the following compounds.
BTDA: 3,3',4,4'-benzophenonetetracarboxylic dianhydride DDA: Made by Croda Japan Co., Ltd., product name: PRIAMINE 1075 distilled and purified (component a: 99.2% by weight, component b: 0 %, c component; 0.8%, amine value: 210mg KOH/g)
N-12: Dodecanedioic acid dihydrazide NMP: N-methyl-2-pyrrolidone filler 1: Nippon Steel Chemical & Materials Co., Ltd., product name: CR10-20 (spherical cristobalite silica powder, true spherical, silica content: 99.4 Weight %, cristobalite crystal phase; 93 weight %, true specific gravity; 2.33, D ₅₀ ; 10.8 μm, D ₉₀ ; 16.4 μm, D ₁₀₀ ; 24.1 μm, dielectric constant at 10 GHz; 3.16, 10 GHz dielectric loss tangent; 0.0008)
Filler 2: manufactured by Nippon Steel Chemical & Materials Co., Ltd., trade name: SC70-2 (spherical amorphous silica powder, true spherical, silica content: 99.9% by weight, true specific gravity: 2.21, _D50 : 11. 7 μm, D ₉₀ ; 16.4 μm, D ₁₀₀ ; 24.1 μm, dielectric constant at 10 GHz: 3.08, dielectric loss tangent at 10 GHz; 0.0015)
In addition, in the above DDA, "%" of component a, component b, and component c means the area percentage of the chromatogram in GPC measurement. Moreover, the molecular weight of DDA was calculated using the following formula (1).
Molecular weight = 56.1 x 2 x 1000/amine value... (1)

(Synthesis example 1)
A 1000 ml separable flask was charged with 55.51 g of BTDA (0.1721 mol), 94.49 g of DDA (0.1735 mol), 210 g of NMP and 140 g of xylene, and mixed well for 1 hour at 40°C. A polyamic acid solution was prepared. This polyamic acid solution was heated to 190°C, heated and stirred for 10 hours, and 125 g of xylene was added to complete imidization. Polyimide solution 1 (solid content: 30% by weight, weight average molecular weight: 80,900) Prepared.

[Example 1]
Add 1.09 g of N-12 and 7.50 g of Filler 1 to 100 g of polyimide solution 1 prepared in Synthesis Example 1, dilute by adding xylene so that the solid content is 30% by weight, and stir. Polyimide varnish 1a was thus prepared.

[Examples 2 to 8]
Polyimide varnishes 2a to 8a were prepared in the same manner as in Example 1, except that the amounts of Filler 1 and Filler 2 were changed as shown in Table 1.

Comparative example 1
Polyimide varnish 9a was prepared in the same manner as in Example 1 except that Filler 1 was not blended.

[Example 9]
The adhesive sheet 1b (thickness: 25 μm) was prepared by applying the polyimide varnish 1a prepared in Example 1 to one side of the release-treated PET film, drying it at 80° C. for 15 minutes, and then peeling it off. Prepared.
Various evaluation results of the adhesive sheet 1b are as follows.
Specific permittivity: 2.7, dielectric loss tangent: 0.0015, tensile modulus: 0.6 GPa, maximum elongation: 165%, Tg: 56°C, film retention: Good, solder heat resistance test (drying): 320°C , Solder heat resistance test (moisture absorption): 260℃, Peel strength: 1.8 kN/m, Flame retardancy: Good

[Example 10]
An adhesive sheet 2b was prepared in the same manner as in Example 9 using the polyimide varnish 2a.
Various evaluation results of the adhesive sheet 2b are as follows.
Specific dielectric constant: 2.9, dielectric loss tangent: 0.0013, tensile modulus: 0.5 GPa, maximum elongation: 77%, Tg: 56°C, film retention: Good, solder heat resistance test (drying): 320°C , Solder heat resistance test (moisture absorption): 260℃, Peel strength: 1.8 kN/m, Flame retardancy: Good

[Example 11]
An adhesive sheet 3b was prepared in the same manner as in Example 9 using the polyimide varnish 3a.
Various evaluation results of the adhesive sheet 3b are as follows.
Specific permittivity: 2.8, dielectric loss tangent: 0.0012, tensile modulus: 0.6 GPa, maximum elongation: 59%, Tg: 56°C, film retention: Good, solder heat resistance test (drying): 320°C , Solder heat resistance test (moisture absorption): 270℃, Peel strength: 1.8 kN/m, Flame retardancy: Good

[Example 12]
An adhesive sheet 4b was prepared in the same manner as in Example 9 using polyimide varnish 4a.
Various evaluation results of the adhesive sheet 4b are as follows.
Specific permittivity: 2.8, dielectric loss tangent: 0.0011, tensile modulus: 0.8 GPa, maximum elongation: 31%, Tg: 56°C, film retention: Good, solder heat resistance test (drying): 320°C , Solder heat resistance test (moisture absorption): 280℃, Peel strength: 1.9 kN/m, Flame retardancy: Good

[Example 13]
An adhesive sheet 5b was prepared in the same manner as in Example 9 using the polyimide varnish 5a.
Various evaluation results of the adhesive sheet 5b are as follows.
Specific permittivity: 2.8, dielectric loss tangent: 0.0016, tensile modulus: 0.8 GPa, maximum elongation: 29%, Tg: 56°C, film retention: Good, solder heat resistance test (drying): 320°C , Solder heat resistance test (moisture absorption): 270℃, Peel strength: 1.9 kN/m, Flame retardancy: Good

[Example 14]
An adhesive sheet 6b was prepared in the same manner as in Example 9 using polyimide varnish 6a.
Various evaluation results of the adhesive sheet 6b are as follows.
Specific permittivity: 2.7, dielectric loss tangent: 0.0015, tensile modulus: 0.6 GPa, maximum elongation: 169%, Tg: 56°C, film retention: Good, solder heat resistance test (drying): 320°C , Solder heat resistance test (moisture absorption): 260℃, Peel strength: 1.7kN/m, Flame retardancy: Good

[Example 15]
An adhesive sheet 7b was prepared in the same manner as in Example 9 using polyimide varnish 7a.
Various evaluation results of the adhesive sheet 7b are as follows.
Specific permittivity: 2.8, dielectric loss tangent: 0.0012, tensile modulus: 0.7 GPa, maximum elongation: 28%, Tg: 56°C, film retention: Good, solder heat resistance test (drying): 320°C , Solder heat resistance test (moisture absorption): 280℃, Peel strength: 1.8 kN/m, Flame retardancy: Good

[Example 16]
An adhesive sheet 8b was prepared in the same manner as in Example 9 using polyimide varnish 8a.
Various evaluation results of the adhesive sheet 8b are as follows.
Specific permittivity: 2.6, dielectric loss tangent: 0.0016, tensile modulus: 0.5 GPa, maximum elongation: 177%, Tg: 56°C, film retention: Good, solder heat resistance test (drying): 320°C , Solder heat resistance test (moisture absorption): 260℃, Peel strength: 1.7kN/m, Flame retardancy: OK

Comparative example 2
An adhesive sheet 9b was prepared in the same manner as in Example 9 using polyimide varnish 9a.
Various evaluation results of the adhesive sheet 9b are as follows.
Specific permittivity: 2.6, dielectric loss tangent: 0.0017, tensile modulus: 0.4 GPa, maximum elongation: 197%, Tg: 56°C, film retention: Good, solder heat resistance test (drying): 320°C , Solder heat resistance test (moisture absorption): 220℃, Peel strength: 1.6 kN/m, Flame retardancy: Not possible

The above results are summarized in Table 2.

From Table 2, compared to adhesive sheet 9b of Comparative Example 2, adhesive sheets 1b to 8b of Examples 9 to 16 to which Filler 1 and Filler 2 were added had improved dielectric properties and solder heat resistance temperature (moisture absorption). It was confirmed that From these results, the adhesive sheet as a resin film according to this embodiment can be expected to reduce transmission loss in a high frequency band of 20 GHz, for example. In addition, compared to the adhesive sheet 9b of Comparative Example 2, the adhesive sheets 1b to 8b of Examples 9 to 16 to which fillers 1 and 2 were added had excellent moisture absorption and soldering heat resistance while maintaining flexibility and film retention. It was confirmed that peel strength and flame retardancy were improved.

As shown in the examples above, a clear dielectric loss tangent reduction effect was observed by adding cristobalite silica particles to DDA/BTDA polyimide.
In addition, when flame retardancy was evaluated using the layer structure of polyimide film/adhesive layer/polyimide film, it was confirmed that the adhesive layer containing cristobalite silica particles exhibited flame retardancy of VTM-1 level or higher. Ta.
Further, the adhesive sheets obtained in each example maintain their film shape and have improved adhesive strength to polyimide or copper at a practical range of cristobalite silica particles. Although the mechanism of the improvement in adhesive strength has not been elucidated, it is speculated that the improvement in the elastic modulus of the adhesive sheet may be contributing.
In addition, the soldering heat resistance (drying/moisture absorption) of the adhesive sheet obtained in the example was equal to or higher than that of a comparative example that did not contain cristobalite silica particles, and showed suitable characteristics as an adhesive for high-frequency multilayer FPC.

From the above results, it was confirmed that the resin film according to the present embodiment can be suitably used as a material for a high frequency compatible flexible printed circuit board.

Although the embodiments of the present invention have been described above in detail for the purpose of illustration, the present invention is not limited to the above embodiments and can be modified in various ways.

Claims (6)

The following components (A) and (B),
(A) A dimer diamine whose main component is a tetracarboxylic anhydride component and a dimer diamine obtained by replacing the two terminal carboxylic acid groups of a dimer acid with a primary aminomethyl group or an amino group with respect to all diamine components. A nonvolatile organic compound component containing a polyamic acid or polyimide obtained by reacting a diamine component containing 40 mol% or more of the composition, and (B) an X-ray diffraction analysis spectrum using CuKα rays with 2θ = 10° to 90 Silica particles in which the ratio of the total area of peaks derived from cristobalite crystal phase and quartz crystal phase to the total area of all peaks derived from SiO ₂ in the range of 20% by weight or more,
and the component (B) is within the range of 5 to 60% by weight based on the total of the component (A) (however, polyamic acid is converted to imidized polyimide) and the component (B). A certain resin composition. According to claim 1, the average particle diameter _D50 at which the cumulative value in the frequency distribution curve obtained by volume-based particle size distribution measurement using a laser diffraction scattering method of the component (B) is 50% is within the range of 6 to 20 μm. resin composition. A claim that the component (A) contains a total of 90 mol% or more of a tetracarboxylic anhydride represented by the following general formula (1) and/or (2) based on the total tetracarboxylic anhydride component. Item 2. The resin composition according to item 1 or 2 .

[In general formula (1), X represents a single bond or a divalent group selected from the following formula, and in general formula (2), the cyclic moiety represented by Y is a 4-membered ring, a 5-membered ring, Indicates that a cyclic saturated hydrocarbon group selected from a ring, a 6-membered ring, a 7-membered ring, or an 8-membered ring is formed. ]

[In the above formula, Z represents -C ₆ H ₄ -, -(CH ₂ )n- or -CH ₂ -CH(-O-C(=O)-CH ₃ )-CH ₂ -, but n is Indicates an integer from 1 to 20. ] A resin film including a polyimide layer,
A resin film, wherein the polyimide layer is formed from the resin composition according to any one of claims 1 to 3 . The resin film according to claim 4 , having a thickness within the range of 15 to 100 μm. The resin film according to claim 4 or 5, wherein the (B) component is within a range of 3 to 41% by volume based on the total of the (A) component and the (B) component.