Resin composition, resin film, copper foil with resin, multilayer wiring board, coil structure, magnetic device, and insulated electric wire

Abstract

A resin composition comprising (X) a resin, (Y) a phosphorus-based flame retardant, and (Z) aluminum hydroxide, wherein the blended amount of the (Y) component is 5-30 parts by mass with respect to 100 parts by mass of the (X) component, and the blended amount of the (Z) component is 10-50 parts by mass with respect to 100 parts by mass of the (X) component.

Description

Resin composition, resin film, copper foil with resin, multilayer wiring board, coil structure, magnetic device, and insulated wire

[0001] The present invention relates to a resin composition, a resin film, a copper foil with resin, a multilayer wiring board, a coil structure, a magnetic device, and an insulated wire.

[0002] As a thin transformer, which is one of magnetic devices, for example, Patent Document 1 describes a thin transformer including a printed coil and a core made of a magnetic material, and a pedestal with terminals for mounting the printed coil and the core. This thin transformer is characterized in that the surface where the conductor of the printed coil is exposed is covered with a heat-resistant resin.

[0003] Japanese Patent Application Laid-Open No. 9-326316

[0004] However, in recent years, magnetic devices are required to handle higher voltages and larger currents. When using a conventional prepreg (glass cloth base material / epoxy resin) as the heat-resistant resin layer, it was impossible to satisfy both sufficient thinness and sufficient withstand voltage. Furthermore, the conventional prepreg had a problem of high dielectric constant.

[0005] On the other hand, by using a resin film obtained by removing the glass cloth base material from the conventional prepreg, it is possible to reduce the dielectric constant. However, such a resin film had insufficient flame retardancy and the like. And even if a flame retardant is added to the resin film, the phosphorus-based flame retardant is effective in improving the flame retardancy, but tends to deteriorate the durability and tracking resistance. Also, aluminum hydroxide, which is one of the flame retardants, improves the tracking resistance and flame retardancy, but the effect as a flame retardant is inferior to that of the phosphorus-based flame retardant, and a large amount of addition is required. Thus, a resin film that satisfies all of low dielectric constant, flame retardancy, durability, and tracking resistance has not been obtained.

[0006] An object of the present invention is to provide a resin composition having a low dielectric constant and excellent flame retardancy, durability, and tracking resistance, and a resin film, a copper foil with resin, a multilayer wiring board, a coil structure, a magnetic device, and an insulated wire using the same.

[0007] The present invention provides the following resin compositions, resin films, resin-coated copper foils, multilayer wiring boards, coil structures, magnetic devices, and insulated wires. [1] A resin composition comprising (X) a resin, (Y) a phosphorus-based flame retardant, and (Z) aluminum hydroxide, wherein the amount of component (Y) is 5 parts by mass or more and 30 parts by mass or less per 100 parts by mass of component (X), and the amount of component (Z) is 10 parts by mass or more and 50 parts by mass or less per 100 parts by mass of component (X). [2] The resin composition according to [1], wherein the (X) resin contains a polyimide obtained by imidizing (X1) polyamic acid. [3] The resin composition according to [2], wherein the polyamic acid is a polyaddition reaction product of (A) an acid dianhydride and (B) a diamine. [4] A resin composition according to [3], wherein the polyamic acid contains (B1) dimeramine in a molar ratio of 0.2 or more relative to the total diamine components. [5] A resin composition according to any one of [2] to [4], wherein the (A) acid dianhydride has a structure represented by the following formula (1).

[0008]

[0009] (In formula (1), Ar represents a substituted or unsubstituted arylene group.) [6] A resin film comprising the resin composition described in any of [1] to [5]. [7] A resin-coated copper foil comprising the resin film described in [6] and a copper foil laminated on the resin film. [8] A multilayer wiring board comprising an insulating layer formed using the resin film described in [6]. [9] A coil structure comprising an insulating layer formed using the resin film described in [6].

[10] A magnetic device comprising an insulating layer formed using the resin film described in [6].

[11] An insulated wire comprising an insulating layer made of the resin composition described in any of [1] to [5] and a wire covered with the insulating layer.

[0010] According to one aspect of the present invention, a resin composition with a low dielectric constant and excellent flame retardancy, durability, and tracking resistance can be provided, as well as a resin film, resin-coated copper foil, multilayer wiring board, coil structure, magnetic device, and insulated wire using the same.

[0011] [Resin Composition] The resin composition according to this embodiment contains (X) resin, (Y) phosphorus-based flame retardant, and (Z) aluminum hydroxide. The amount of component (Y) is 5 parts by mass or more and 30 parts by mass or less per 100 parts by mass of component (X). The amount of component (Z) is 10 parts by mass or more and 50 parts by mass or less per 100 parts by mass of component (X).

[0012] (Component (X)) Any known resin can be used as the (X) resin in this embodiment. Examples of component (X) include (X1) a resin containing polyimide obtained by imidizing polyamic acid, and (X2) a resin containing epoxy resin, an aromatic amine curing agent, and a solvent-soluble polyimide resin.

[0013] (Component (X1)) The polyamic acid used in this embodiment is preferably a polyaddition reaction product of (A) an acidic dianhydride and (B) a diamine. Furthermore, this polyamic acid preferably contains (B1) dimeramine in a molar ratio of 0.2 or more relative to the total diamine component. That is, the polyimide formed using the polyamic acid used in this embodiment has an ester skeleton and a dimer skeleton, and low water absorption can be achieved due to the ester skeleton. Furthermore, low dielectric properties are exhibited due to the dimer skeleton, and by including a certain amount of dimeramine as the diamine component, the dielectric constant and dielectric loss tangent can be further reduced, thereby achieving the desired low dielectric properties. In addition, a polyimide with excellent thermal decomposition resistance can be formed.

[0014] (Component (A)) The polyamic acid used in this embodiment uses (A) an acid dianhydride as one of its raw materials. Any known acid dianhydride can be used as appropriate. Examples of acid dianhydride components include 3,3',4,4'-biphenyltetracarboxylic acid dianhydride, pyromellitic acid dianhydride, 4,4'-(hexafluoroisopropylidene)diphthalic acid anhydride, and ester-type acid dianhydrides having ester bonds in the molecule. In this embodiment, it is preferable that the acid dianhydride component has structural units derived from ester-type acid dianhydrides having ester bonds in the molecule. By having structural units derived from ester-type acid dianhydrides in the polyamic acid, low water absorption can be imparted to the resulting polyimide. The acid dianhydride has two acid anhydride groups in one molecule, and is preferably a tetracarboxylic acid dianhydride, and more preferably an aromatic tetracarboxylic acid dianhydride. There may be one or more ester bonds in the molecule, preferably one to three, and more preferably one or two. Acidic dianhydrides may be used individually or in combination of two or more types.

[0015] Such acidic dianhydrides preferably have the structure shown in the following formula (1). In formula (1), Ar represents a substituted or unsubstituted arylene group, and a substituted arylene group means that the hydrogen atoms of an unsubstituted arylene group are substituted with any substituent. The number of carbon atoms in the substituted or unsubstituted arylene group (excluding the number of carbon atoms of the substituent) is preferably 6 or more and 20 or less, and more preferably 6 or more and 12 or less.

[0016]

[0017] In formula (1), examples of unsubstituted arylene groups in Ar include o-phenylene, m-phenylene, p-phenylene, 2,6-naphthylene, and 4,4'-biphenylene groups. Among these, p-phenylene, 2,6-naphthylene, or 4,4'-biphenylene groups are preferred.

[0018] Examples of substituents on the substituted arylene group include C1-C8 alkyl groups, halogen atoms (fluorine, chlorine, bromine, or iodine atoms), and halogenated alkyl groups in which the hydrogen atoms of the alkyl group are substituted with the halogen atoms. Among these substituents, C1-C8 alkyl groups are preferred, and methyl groups are more preferred. The number of substituents may be one or two or more. If there are two or more substituents, they may be the same or different. Specific examples of substituted arylene groups include the 2,2',3,3',5,5'-hexamethyl-4,4'-biphenylylene group.

[0019] Preferred examples of the acid dianhydride represented by formula (1) include the compound represented by the following formula (1-1) and the compound represented by the following formula (1-2) (TAHQ), with the compound represented by the following formula (1-2) (TMPBP-TME) being more preferred.

[0020]

[0021] (Component (B)) The polyamic acid used in this embodiment uses (B) diamine as one of its raw materials. Any known diamine can be used as appropriate. The diamine component has structural units derived from a diamine, and one of the diamine components has structural units derived from (B1) dimer amine. Here, dimer amine is a cyclic or acyclic dimer acid obtained as a dimer of an unsaturated fatty acid in which two terminal carboxylic acid groups (-COOH) are primary aminomethyl groups (-CH ２ -NH ２ ) or amino group (-NH ２ This refers to an aliphatic diamine substituted with (B1). By having a polyamic acid with structural units derived from dimer amine, low dielectric properties can be imparted to the resulting polyimide. (B1) Dimer amine may be used alone or in combination of two or more types.

[0022] Dimer acids are dibasic acids obtained by the intermolecular polymerization reaction of unsaturated fatty acids. Aliphatic diamines derived from dimer acids are obtained by polymerizing unsaturated fatty acids such as oleic acid, linoleic acid, or linolenic acid to form dimer acids, reducing them, and then aminating them. Such dimer amines are preferably diamine compounds obtained by substituting the terminal carboxylic acid group of a dibasic acid compound having 18 to 54 carbon atoms, preferably 22 to 44 carbon atoms, with a primary aminomethyl group or an amino group.

[0023] Commercially available dimeramines include "Versamin® 551" and "Versamin® 552" from Cognics Japan, and "PRIAMINE® 1073," "PRIAMINE® 1074," and "PRIAMINE® 1075" from Croda Japan.

[0024] Furthermore, the polyamic acid used in this embodiment contains (B1) dimeramine in a molar ratio of 0.2 or more relative to the total diamine components. By including dimeramine in a specific molar ratio or higher relative to the total diamine, the resulting polyimide can be given a lower dielectric constant and a lower dielectric loss tangent. The molar ratio of (B1) dimeramine to the total diamine components is preferably 0.3 or higher, and more preferably 0.4 or higher.

[0025] The polyamic acid used in this embodiment preferably contains a (B2) aromatic diamine as another diamine component. Examples of (B2) aromatic diamines include p-phenylenediamine (PDA), m-phenylenediamine, 4,4'-oxydianiline (ODA), 3,3'-bistrifluoromethyl-4,4'-diaminobiphenyl (TFMB), 3,4'-diaminodiphenyl ether, 4,4'-diaminodiphenylmethane, 3,3'-dimethyl-4,4'-diaminodiphenylmethane, 2,2-bis[4-(4-aminophenoxy)phenyl]propane, 1,2-bis(anilino)ethane, diaminodiphenylsulfone, Examples include diaminobenzanilide, diaminobenzoate, diaminodiphenyl sulfide, 2,2-bis(p-aminophenyl)propane, 2,2-bis(p-aminophenyl)hexafluoropropane, 1,5-diaminonaphthalene, diaminotoluene, diaminobenzotrifluoride, 1,4-bis(p-aminophenoxy)benzene, 4,4'-bis(p-aminophenoxy)biphenyl, diaminoanthraquinone, and 4,4'-bis(3-aminophenoxyphenyl)diphenylsulfone. Among these aromatic diamines, PDA, ODA, or TFMB are preferred, with ODA being more preferred. (B2) Aromatic diamines may be used alone or in combination of two or more.

[0026] The molar ratio of diamine to acidic dianhydride [(B) / (A)] is not particularly limited, but is preferably 0.90 or more and 1.10 or less, more preferably 0.95 or more and 1.05 or less, even more preferably 0.97 or more and 1.03 or less, and particularly preferably 0.98 or more and 1.02 or less.

[0027] (Component (C)) The polyamic acid used in this embodiment can be synthesized by known general methods. For example, a polyamic acid composition (polyamic acid solution) can be obtained by reacting (A) an acidic dianhydride and (B) a diamine in (C) an organic solvent. The organic solvent used for polymerization of polyamic acid is not particularly limited as long as it can dissolve the acidic dianhydride and diamine as monomer components and also dissolve the polyamic acid produced by the polyaddition reaction. Examples of such organic solvents include urea-based solvents such as tetramethylurea and N,N-dimethylethylurea; sulfone-based solvents such as dimethyl sulfoxide, diphenyl sulfone, and tetramethyl sulfone; amide-based solvents such as N,N-dimethylacetamide, N,N-dimethylformamide, N,N-diethylacetamide, N-methyl-2-pyrrolidone, and hexamethylphosphate triamide; ester-based solvents such as γ-butyrolactone; alkyl halide-based solvents such as chloroform and methylene chloride; aromatic hydrocarbon-based solvents such as benzene and toluene; phenol-based solvents such as phenol and cresol; ketone-based solvents such as cyclopentanone; and ether-based solvents such as tetrahydrofuran, 1,3-dioxolane, 1,4-dioxane, dimethyl ether, diethyl ether, and p-cresol methyl ether. These organic solvents may be used individually or in combination of two or more. From the viewpoint of enhancing the solubility and reactivity of polyamic acids, the organic solvent is preferably selected from the group consisting of amide solvents, ketone solvents, ester solvents, and ether solvents, with amide solvents such as N,N-dimethylacetamide, N,N-dimethylformamide, N,N-diethylacetamide, and N-methyl-2-pyrrolidone being more preferred.

[0028] The molecular weight of polyamic acid can be adjusted by adjusting the molar ratio of the total number of moles of the acid dianhydride component to the total number of moles of the diamine component. The molecular weight (weight-average molecular weight) of polyamic acid is not particularly limited, but from the viewpoint of solubility in organic solvents, it is more preferable to be between 10,000 and 100,000. The weight-average molecular weight of polyamic acid can be determined, for example, from the value converted to standard polystyrene by gel filtration chromatography (GPC) measurement.

[0029] The synthesis of polyamic acids by the polyaddition reaction of acidic dianhydrides and diamines is preferably carried out in an inert atmosphere such as argon or nitrogen. In an inert atmosphere, the polyaddition reaction proceeds by dissolving the acidic dianhydride and diamine in an organic solvent and mixing them. The order of addition of the acidic dianhydride and diamine is not particularly limited. For example, the diamine may be dissolved in an organic solvent or dispersed in a slurry to form a diamine solution, and the acidic dianhydride may be added to the diamine solution. The acidic dianhydride and diamine may be added directly to the organic solvent in a solid state, or they may be added separately dissolved in an organic solvent or dispersed in a slurry.

[0030] The temperature conditions for the polyaddition reaction are not particularly limited, but from the viewpoint of suppressing the decrease in molecular weight of the polyamic acid due to depolymerization, the reaction temperature is preferably 100°C or lower, and from the viewpoint of allowing the polyaddition reaction to proceed appropriately, the reaction temperature is more preferably 20°C to 80°C. The reaction time can be arbitrarily set in the range of 1 hour to 72 hours, and if necessary, it may be left overnight at room temperature.

[0031] When preparing the polyamic acid composition used in this embodiment, the viscosity of the solution is preferably 500 mPa·s or higher from the viewpoint of film-forming properties. Furthermore, the concentration of polyamic acid in the polyamic acid composition used in this embodiment is preferably 10% by mass or higher, more preferably 15% by mass or higher, and even more preferably 25% by mass or higher. In particular, if the concentration of polyamic acid is 15% by mass or higher, the productivity when forming a polyimide coating film using polyamic acid can be increased. Furthermore, the upper limit of the concentration of polyamic acid is preferably 50% by mass or lower, and even more preferably 30% by mass or lower, from the viewpoint of sufficiently dissolving the polyamic acid in the organic solvent.

[0032] (Component (X2)) The (X) resin used in this embodiment may also be a resin containing (X2) epoxy resin, an aromatic amine-based curing agent, and a solvent-soluble polyimide resin. This (X2) can also improve the dielectric breakdown strength of the cured product of the resin composition.

[0033] The resin composition containing component (X2) may be B-staged by heat. By B-staged this resin composition, a resin film with sufficient fluidity and adhesion can be obtained.

[0034] Any epoxy resin having two or more glycidyl groups can be used. Suitable epoxy resins include bisphenol A type epoxy resin, bisphenol F type epoxy resin, novolacphenol type epoxy resin, biphenyl type epoxy resin, naphthalene type epoxy resin, and dicyclopentadiene type epoxy resin. These may be used individually or in combination of two or more types.

[0035] Aromatic amine curing agents are not particularly limited as long as they have an aromatic group and an amino group and have the effect of accelerating the curing of epoxy resins when irradiated with light. Examples of aromatic groups include phenyl groups, biphenyl groups, and fluorenyl groups. Examples of aromatic amine curing agents include polytetramethylene oxide-di-p-aminobenzoate, 4,4'-diaminodiphenylsulfone, 4,4'-bis(4-aminophenoxy)biphenyl, 2,2-bis[4-(4-aminophenoxy)phenyl]propane, bis[4-(4-aminophenoxy)phenyl]sulfone, 1,3-bis(4-aminophenoxy)benzene, 1,4-bis(4-aminophenoxy)benzene, trimethylenebis( Examples include 4-aminobenzoate, 3,3'-dimethyl-4,4'-diaminobiphenyl, 2,2'-dimethyl-4,4'-diaminobiphenyl, 4,4'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, bis[4-(3-aminophenoxy)phenyl]sulfone, 9,9'-bis(4-aminophenyl)fluorene, and 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane. These may be used individually or in combination of two or more.

[0036] When the number of moles of epoxy resin is set to 1, the amount of aromatic amine-based curing agent used is preferably 0.2 moles or more and 1.5 moles or less. If the amount used is above the lower limit, it tends to be easier to obtain appropriate toughness and chemical resistance. On the other hand, if the amount used is below the upper limit, it tends to be easier to obtain appropriate Tg and thermal expansion coefficient.

[0037] The solvent-soluble polyimide resin is a polyimide resin that is soluble in the solvent used in the production of the second adhesive resin composition used in this embodiment. Preferred solvent-soluble polyimide resins have high Tg, low thermal expansion coefficient, excellent film properties, low dielectric constant, and low dielectric loss tangent. Examples of solvent-soluble polyimide resins include fully imidized soluble polyimide resins obtained by reacting diaminotrimethylphenylindan with benzophenonetetracarboxylic acid 2-anhydride. This compound can improve adhesive strength without the need for other adhesion-imparting agents. The number-average molecular weight (Mn) of the solvent-soluble polyimide resin is not particularly limited, but is preferably between 10,000 and 50,000, and particularly preferably between 12,000 and 20,000.

[0038] When the total amount of epoxy resin and aromatic amine-based curing agent is 100 parts by mass, the amount of solvent-soluble polyimide resin blended is preferably 10 parts by mass or more and 100 parts by mass or less, and particularly preferably 15 parts by mass or more and 100 parts by mass or less. If the blending amount is above the lower limit, it tends to be easier to obtain an improvement in adhesive strength and flexibility. If the blending amount is below the upper limit, it tends to be easier to ensure the breaking strength of the film.

[0039] (Component (Y)) Any known phosphorus-based flame retardant can be used as the (Y) phosphorus-based flame retardant in this embodiment. Examples of phosphorus-based flame retardants include halogen-containing phosphate esters such as tris(chloroethyl) phosphate, tris(2,3-dichloropropyl) phosphate, tris(2-chloropropyl) phosphate, tris(2,3-bromopropyl) phosphate, tris(bromochloropropyl) phosphate, 2,3-dibromopropyl-2,3-chloropropyl phosphate, tris(tribromophenyl) phosphate, tris(dibromophenyl) phosphate, and tris(tribromoneopentyl) phosphate. Non-halogenated aliphatic phosphate esters such as trimethyl phosphate, triethyl phosphate, tributyl phosphate, trioctyl phosphate, and tributoxyethyl phosphate; triphenyl phosphate, cresyl diphenyl phosphate, dicresyl phenyl phosphate, tricresyl phosphate, trixylenyl phosphate, xylenyl diphenyl phosphate, tris(isopropylphenyl) phosphate, isopropylphenyl diphenyl phosphate, diisopropylphenyl Examples include non-halogenated aromatic phosphate esters such as triphenyl phosphate, tris(trimethylphenyl) phosphate, tris(t-butylphenyl) phosphate, hydroxyphenyldiphenyl phosphate, and octyldiphenyl phosphate; metal salts of phosphinic acids such as aluminum trisdiethylphosphinate, aluminum trismethylethylphosphinate, aluminum trisdiphenylphosphinate, zinc bisdiethylphosphinate, zinc bismethylethylphosphinate, zinc bisdiphenylphosphinate, titanyl bisdiethylphosphinate, titanium tetrakisdiethylphosphinate, titanium bismethylethylphosphinate, titanium tetrakismethylethylphosphinate, titanyl bisdiphenylphosphinate, and titanium tetrakisdiphenylphosphinate; and phosphin oxide compounds such as diphenylvinylphosphin oxide, triphenylphosphin oxide, trialkylphosphin oxide, and tris(hydroxyalkyl)phosphin oxide.

[0040] The blending amount of the (Y) component needs to be 5 parts by mass or more and 30 parts by mass or less with respect to 100 parts by mass of the (X) component. When the blending amount of the (Y) component is less than 5 parts by mass, the flame retardancy of the resulting resin film becomes insufficient. On the other hand, when the blending amount of the (Y) component exceeds 30 parts by mass, the durability and tracking resistance of the resulting resin film become insufficient. From the same viewpoint, the blending amount of the (Y) component is preferably 6 parts by mass or more and 18 parts by mass or less, more preferably 7 parts by mass or more and 15 parts by mass or less, and particularly preferably 8 parts by mass or more and 12 parts by mass or less with respect to 100 parts by mass of the (X) component. ((Z) component) The aluminum hydroxide (Z) used in this embodiment can be appropriately used as one of the known flame retardants. The blending amount of the (Z) component needs to be 10 parts by mass or more and 50 parts by mass or less with respect to 100 parts by mass of the (X) component. When the blending amount of the (Z) component is less than 10 parts by mass, the flame retardancy of the resulting resin film becomes insufficient. On the other hand, when the blending amount of the (Z) component exceeds 50 parts by mass, the durability of the resulting resin film becomes insufficient. From the same viewpoint, the blending amount of the (Z) component is preferably 12 parts by mass or more and 40 parts by mass or less, more preferably 14 parts by mass or more and 30 parts by mass or less, and particularly preferably 16 parts by mass or more and 25 parts by mass or less with respect to 100 parts by mass of the (X) component.

[0041] In the resin composition according to this embodiment, in addition to the (X) component to the (Z) component, a extender pigment, a curing accelerator, a colorant, a surfactant, a leveling agent, a plasticizer, a sensitizer, a silane coupling agent, and a non-reactive diluent can be blended as necessary.

[0042] The method for producing the resin composition according to this embodiment is not limited to a specific method. For example, after blending the above components in a predetermined ratio, at room temperature, kneading or mixing can be performed by kneading means such as a three-roll mill, a ball mill, a sand mill, or stirring means such as a super mixer or a planetary mixer. Also, before the kneading or mixing, pre-kneading or pre-mixing may be performed as necessary.

[0043] [Resin Film] The resin film according to this embodiment is a resin film made of the resin composition according to the above-described embodiment. For example, taking the resin film made of the resin composition containing the component (X1) as an example, the resin film made of the resin composition containing the component (X1) is a resin film containing polyimide obtained by imidizing the polyamic acid according to the above-described embodiment. The method for converting polyamic acid to polyimide is not particularly limited, but polyimide can be produced by dehydrating and cyclizing (imidizing) the polyamic acid obtained as described above. Known methods such as thermal imidization by dehydrating and cyclizing with heat or chemical imidization by chemically cyclizing using a known dehydrating and cyclizing catalyst can be employed. Further, after the polyamic acid is imidized to polyimide, a part of the amino groups may be maleimidized.

[0044] In the case of thermal imidization, the heating temperature is preferably 120°C or higher and 350°C or lower, more preferably 150°C or higher and 250°C or lower. The heating time is preferably 3 minutes or longer and 3 hours or shorter, more preferably 5 minutes or longer and 2 hours or shorter. In the case of chemical imidization, as the dehydrating and cyclizing catalyst, for example, pyridine, triethylamine, acetic anhydride, etc. can be used. At this time, the reaction temperature can be any temperature of 20°C or higher and 180°C or lower, but it is preferably 150°C or lower. Also, the reaction time is preferably 1 hour or longer and 3 hours or shorter. The imidization may be carried out under air, under reduced pressure, or in an inert gas such as nitrogen, but in order to obtain a polyimide film with high transparency, it is preferably carried out under reduced pressure or in an inert gas such as nitrogen.

[0045] The molecular weight (weight average molecular weight) of the polyimide is not particularly limited, but from the viewpoints of the low dielectric properties, solubility in organic solvents, or film-forming properties of the obtained polyimide, it is preferably 10,000 or higher and 100,000 or lower. The weight average molecular weight of the polyimide can be determined, for example, from the standard polystyrene conversion value by gel permeation chromatography (GPC) measurement.

[0046] The resin film according to this embodiment contains the polyimide obtained as described above. The method for producing such a resin film is not particularly limited, and examples include coating the above-mentioned polyamic acid composition in a film-like manner onto a substrate (for example, a plastic film made of a resin such as polyethylene, polypropylene, urethane, polyester, polyethylene terephthalate (PET), or polycarbonate, a glass plate, a stainless steel plate, a copper plate including thin copper foil, or an aluminum plate), then drying and heating to remove the solvent and dehydrate and cyclize (imide), or dissolving the polyimide obtained by converting polyamic acid to polyimide in an organic solvent, coating the polyimide solution in a film-like manner onto the substrate, and then drying and removing the solvent. The method of coating onto the substrate is not particularly limited, and conventionally known coating methods can be applied.

[0047] The thickness of the resin film is not particularly limited and can be appropriately selected depending on the application. The thickness of the resin film can be easily controlled by appropriately adjusting the solid content concentration of each component in the polyamic acid composition, the coating thickness, and the viscosity.

[0048] [Applications of the Resin Film] The resin film according to this embodiment can be suitably used in resin-coated copper foil, multilayer wiring boards, coil structures, magnetic devices, and insulated wires. Furthermore, the resin film according to this embodiment can be suitably used as a film for various components such as color filters, flexible displays, semiconductor components, or optical components. Because the polyimide film exhibits insulating properties, it is suitably applied as an insulating substrate for printed wiring boards. In addition, because the polyimide film is a thin and flexible film that exhibits insulating properties, it is also effective as a base film for flexible printed circuit boards (FPCs).

[0049] Next, the present invention will be described in more detail with reference to examples and comparative examples, but the present invention is not limited in any way by these examples. The materials used in the examples and comparative examples are as follows: ((X1) component) Resin A: Varnish containing polyamic acid obtained in Preparation Example 1 ((X2) component) Resin B: Resin varnish obtained in Preparation Example 2 ((Y) component) Phosphorus-based flame retardant: Metal phosphinate salt, trade name "OP-935F", manufactured by Clariant ((Z) component) Aluminum hydroxide: trade name "BF013STV", manufactured by Nippon Light Metal Co., Ltd.

[0050] [Preparation Example 1] A 1 L four-neck separable flask equipped with a stirrer, reflux condenser, and thermometer was charged with 0.5 parts by mass of 4,4'-oxydianiline, 4 parts by mass of dimeramine (CRODA JAPAN, PRIAMINE 1075), 6.2 parts by mass of 2,2',3,3',5,5'-hexamethyl[1,1'-biphenyl]-4,4'-diyl-bis(1,3-dioxo-1,3-dihydro-2-benzofuran-5-carboxylate) (TMPBP-TME), and 32 parts by mass of N-methyl-2-pyrrolidone. The mixture was heated and stirred at 50°C for about 3.5 hours while blowing nitrogen into the reaction vessel at a rate of 0.1 mL / sec. After confirming the dissolution of the salt, the mixture was stirred at room temperature for 24 hours to synthesize polyamic acid, a precursor of polyimide. Then, a varnish containing this polyamic acid (37.5% by mass of resin solids) was prepared.

[0051] [Preparation Example 2] 98 parts by mass of bisphenol A type epoxy resin "Epiclon 850-S" (manufactured by DIC Corporation, epoxy equivalent: 188), 147 parts by mass of dicyclopentadiene type epoxy resin "HP-7200H" (manufactured by DIC Corporation, epoxy equivalent: 283, softening point: 83°C), 126 parts by mass of aromatic amine-based curing agent "Elasmer 250P" (polytetramethylene oxide-di-p-aminobenzoate, manufactured by Ihara Chemical Co., Ltd.) A mixture consisting of 100 parts by mass of soluble polyimide resin "Q-VR-X0163" (manufactured by PI Technical Research Institute, Tg: 246°C, resin solids content: 20% by mass), 303 parts by mass of phenoxy resin "ERF-001M30" (manufactured by Nippon Steel Chemical & Material, Tg: 146°C, resin solids content: 30% by mass), and 18 parts by mass of flame retardant HCA was prepared to create a resin varnish with a resin solids content of 40% by mass.

[0052] [Example 1] 100 parts by mass of resin A (resin solids), 10 parts by mass of phosphorus-based flame retardant, and 20 parts by mass of aluminum hydroxide were placed in a container, pre-mixed with a stirrer, and then mixed and dispersed at room temperature using a three-roll roller to obtain a resin composition.

[0053] [Example 2] A resin composition was obtained in the same manner as in Example 1, except that each material was blended according to the composition shown in Table 1.

[0054] [Comparative Examples 1-7] Resin compositions were obtained in the same manner as in Example 1, except that each material was blended according to the composition shown in Table 1.

[0055] [Evaluation of Resin Composition] The resin composition was evaluated (relative temperature index, tracking resistance, flame retardancy, relative permittivity) using the following method. The results obtained are shown in Table 1. (1) Relative Temperature Index (RTI) First, test specimens were prepared as follows. That is, the resin composition was applied to a substrate (PET film, thickness: 38 μm, with release treatment) using a bar coater, pre-dried at 100°C for 30 minutes, then fully dried at 160°C for 1 hour, and then heat-cured at 190°C for 30 to 90 minutes to prepare test specimens of a predetermined size. The RTI of the obtained test specimens was measured in accordance with the method described in UL-746. The relative temperature index was then evaluated according to the following criteria. A: RTI is 130°C or higher. B: RTI is 120°C or higher and less than 130°C. C: RTI is less than 120°C. (2) Except for the size of the tracking resistance test specimen, test specimens of a predetermined size were prepared in the same manner as the relative temperature index test specimens in (1). The comparative tracking index (CTI) was measured for the obtained test specimens in accordance with the method described in IEC 60112. The tracking resistance was then evaluated according to the following criteria: A: CTI is 600V or higher. B: CTI is 500V or higher and less than 600V. C: CTI is less than 500V. (3) Except for the size of the flame retardancy test specimen, test specimens of a predetermined size were prepared in the same manner as the relative temperature index test specimens in (1). The obtained test specimens were tested in accordance with the method described in UL 94, and the flame retardancy was evaluated according to the following criteria: A: Equivalent to VTM-0 and equivalent to V-0. B: Equivalent to VTM-0 and not equivalent to V-0. C: Not equivalent to VTM-0 and not equivalent to V-0. (4) Except for the size of the relative permittivity test specimen, a test specimen of the specified size was prepared in the same manner as the test specimen for the relative temperature index in (1). The relative permittivity of the obtained test specimen (20 mm × 20 mm × 200 μm thickness) was measured at a frequency of 1 MHz using a KEYSIGHT "RF Impedance / Material Analyzer, 1.8 GHz 4291b". The relative permittivity was then evaluated according to the following criteria. A: The relative permittivity is 2.8 or less.B: The relative permittivity is greater than 2.8 and 3.5 or less. C: The relative permittivity is greater than 3.5.

[0056]

[0057] As is clear from the results shown in Table 1, when the resin composition according to the present invention was used (Examples 1 and 2), it was confirmed that all results for relative temperature index, tracking resistance, flame retardancy, and dielectric constant were good. Therefore, it was confirmed that the present invention can yield a resin composition with a low dielectric constant and excellent flame retardancy, durability, and tracking resistance.

Claims

1. A resin composition comprising (X) a resin, (Y) a phosphorus-based flame retardant, and (Z) aluminum hydroxide, wherein the amount of component (Y) is 5 parts by mass or more and 30 parts by mass or less per 100 parts by mass of component (X), and the amount of component (Z) is 10 parts by mass or more and 50 parts by mass or less per 100 parts by mass of component (X).

2. The resin composition according to claim 1, wherein the (X) resin contains a polyimide obtained by imidizing (X1) polyamic acid.

3. The resin composition according to claim 2, wherein the polyamic acid is a polyaddition product of (A) an acid dianhydride and (B) a diamine.

4. The resin composition according to claim 3, wherein the polyamic acid contains (B1) dimeramine in a molar ratio of 0.2 or more relative to the total diamine components.

5. In the resin composition according to claim 2, the (A) acid dianhydride has a structure represented by the following formula (1), the resin composition. (In formula (1), Ar represents a substituted or unsubstituted arylene group.) 6. A resin film comprising the resin composition described in any one of claims 1 to 5.

7. A resin-coated copper foil comprising a resin film according to claim 6 and a copper foil laminated on the resin film.

8. A multilayer wiring board comprising an insulating layer formed using the resin film described in claim 6.

9. A coil structure comprising an insulating layer formed using the resin film described in claim 6.

10. A magnetic device comprising an insulating layer formed using the resin film described in claim 6.

11. An insulated electric wire comprising an insulating layer made of the resin composition described in any one of claims 1 to 5, and an electric wire covered with the insulating layer.

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