Adhesive resin composition, resin film, multilayer wiring board, copper foil with resin, coil structure, and magnetic device

Abstract

The purpose of the present invention is to provide: an adhesive resin composition which is capable of forming a resin film that exhibits low dielectric properties while having excellent embedding properties and lamination properties; and a resin film, a multilayer wiring board, a copper foil with a resin, a coil structure, and a magnetic device, each of which is produced using the adhesive resin composition.　The adhesive resin composition contains (A) a polyamic acid and (B) a compound having a maleimide group, wherein the (B) compound having a maleimide group is contained in an amount of 10 mass% to 120 mass% inclusive with respect to 100 mass% of the (A) polyamic acid.

Description

Adhesive resin compositions, resin films, multilayer wiring boards, resin-coated copper foil, coil structures, and magnetic devices

[0001] The present invention relates to adhesive resin compositions, resin films, multilayer wiring boards, resin-coated copper foils, coil structures, and magnetic devices.

[0002] In recent years, development has been underway on high-speed, high-capacity printed circuit boards for next-generation high-frequency wireless communication. The adoption of circuit boards with multilayer wiring structures enables high-speed signal transmission. In these multilayer wiring structures, prepregs, which combine glass fiber cloth and epoxy resin to provide high insulation, adhesion, and inter-wiring embedding properties, are used as adhesives for each electronic circuit board.

[0003] However, epoxy resins typically have high dielectric properties, such as dielectric constant, and high capacitance. This can cause overheating of the wiring near the insulating film during high-speed communication (high frequency) applications, leading to malfunctions of the printed circuit board. Furthermore, their low voltage resistance makes miniaturization of the circuit board difficult.

[0004] To address such high-frequency requirements, there is a growing demand for polyimides that exhibit high insulation and low dielectric properties. For example, Patent Document 1 discloses that a polyimide prepared using an aromatic diamine and a tetracarboxylic dianhydride having a specific structure exhibits a low dielectric constant and also has excellent heat resistance.

[0005] Furthermore, a method is known in which the concentration of imide groups is reduced by introducing a fluorene skeleton into the diamine component, thereby reducing the overall polarity of the molecule and lowering the dielectric constant of the polyimide. For example, Patent Document 2 discloses that a polyimide using trimellitic anhydride chloride as the acid anhydride and 9,9-bis(4-aminophenyl)fluorene as the diamine exhibits high heat resistance and a low dielectric constant.

[0006] On the other hand, when producing polyamic acid films from polyamic acid, a precursor of polyimide, the resin components solidify on the film surface, making it difficult for the solvent to volatilize. If such a film is used to fill gaps between wiring, there is a concern that the remaining solvent will volatilize, creating voids between the wiring and making the film prone to peeling. Therefore, there is a need for the development of resin films that not only have low dielectric properties but also excellent embedding and laminating properties.

[0007] Japanese Patent Publication No. 10-152559 Japanese Patent Publication No. 2005-298625

[0008] In view of the above circumstances, the object of the present invention is to provide an adhesive resin composition that can form a resin film exhibiting low dielectric properties as well as excellent embedding and laminating properties, and a resin film, a multilayer wiring board, a resin-coated copper foil, a coil structure, and a magnetic device made using the same.

[0009] An aspect of the present invention is an adhesive resin composition containing (A) a polyamic acid and (B) a compound having a maleimide group, wherein the composition contains 10% by mass or more and 120% by mass or less of the compound having a maleimide group with respect to 100% by mass of the polyamic acid (A).

[0010] In one embodiment of the present invention, the (A) polyamic acid is a polyaddition product of (A1) an ester-type dianhydride and (A2) at least two diamines.

[0011] In one embodiment of the present invention, the (A1) ester-type dianhydride has a structure represented by the following formula (1). (In formula (1), Ar represents a substituted or unsubstituted arylene group.)

[0012] In one embodiment of the present invention, the compound having the (B) maleimide group has a hydrocarbon structure derived from a dimer acid.

[0013] In one embodiment of the present invention, the compound having the (B) maleimide group is a bismaleimide compound represented by the following formula (2). (In formula (2), R １ , R ２ , R ３ , R４ , R ５ , R ６ , R ７ , R ８ Each of these independently represents a chain-like hydrocarbon group with 2 to 20 carbon atoms, and n represents an integer between 1 and 5.

[0014] In one embodiment of the present invention, the bismaleimide compound represented by formula (2) is a bismaleimide compound represented by the following formula (3). (In equation (3), p, q, r, and s each independently represent an integer between 5 and 10, and n represents an integer between 1 and 5.)

[0015] Another aspect of the present invention is a resin film formed using the above-mentioned adhesive resin composition.

[0016] Another aspect of the present invention is a multilayer wiring board comprising an insulating layer formed using the above-mentioned resin film.

[0017] Another aspect of the present invention is a resin-coated copper foil comprising the above-mentioned resin film and a copper foil laminated on the resin film.

[0018] Another aspect of the present invention is a coil structure comprising an insulating layer formed using the above-mentioned resin film.

[0019] Another aspect of the present invention is a magnetic device comprising an insulating layer formed using the above-mentioned resin film.

[0020] According to the present invention, it is possible to provide an adhesive resin composition that can form a resin film exhibiting low dielectric properties as well as excellent embedding and laminating properties, and a resin film, multilayer wiring board, resin-coated copper foil, coil structure, and magnetic device made using the same.

[0021] Embodiments of the present invention will be described in detail below. The adhesive resin composition of the present invention contains (A) polyamic acid and (B) a compound having a maleimide group, and contains 10% to 120% by mass of the compound having a maleimide group (B) with respect to 100% by mass of polyamic acid (A). Compounds having a maleimide group, such as maleimide resin, are usually liquid at room temperature. Therefore, by blending a maleimide resin with polyamic acid, the solidification of the resin component on the surface of a film formed using such an adhesive resin composition can be suppressed, and the volatility of the solvent is improved. Furthermore, by using such a film, the amount of residual solvent volatilized when embedding between wirings by lamination can be suppressed, and the porosity can be reduced. In addition, since a bismaleimide-containing polyimide adhesive film with a low dielectric constant can be produced, it can be suitably used as a substrate material for high-frequency circuits.

[0022] (A) Polyamic Acid The polyamic acid contained in the adhesive resin composition of the present invention is a polyaddition product of (A1) an ester-type dianhydride and (A2) at least two diamines. That is, the polyamic acid is a resin obtained by ring-opening addition of an ester-type dianhydride and a diamine.

[0023] (A1) Ester-type acid dianhydride polyamic acid has structural units derived from ester-type acid dianhydrides having ester bonds in the molecule as an acid dianhydride component. By having structural units derived from ester-type acid dianhydrides, the resulting polyimide can be imparted with low water absorption. The acid dianhydride has two acid anhydride groups in one molecule, and is preferably a tetracarboxylic dianhydride, and more preferably an aromatic tetracarboxylic dianhydride. There may be one or more ester bonds in the molecule, preferably one to three, and more preferably one or two. Ester-type acid dianhydrides may be used alone, or two or more may be used in combination.

[0024] Such an ester-type acid dianhydride preferably has a structure represented by the following formula (1). In formula (1), Ar represents a substituted or unsubstituted arylene group. A substituted arylene group means that a hydrogen atom of an unsubstituted arylene group is substituted by an arbitrary substituent. The number of carbon atoms of the substituted or unsubstituted arylene group (excluding the carbon atoms of the substituent) is preferably 6 to 20, more preferably 6 to 12.

[0025]

[0026] Examples of the unsubstituted arylene group in the group Ar include an o-phenylene group, a m-phenylene group, a p-phenylene group, a 2,6-naphthylene group, a 4,4'-biphenylylene group, etc. Among these, a p-phenylene group, a 2,6-naphthylene group, and a 4,4'-biphenylylene group are preferred.

[0027] Examples of an arbitrary substituent in the substituted arylene group include an alkyl group having 1 to 8 carbon atoms, a halogen atom (fluorine atom, chlorine atom, bromine atom, iodine atom), a halogenated alkyl group in which a hydrogen atom of the alkyl group is substituted by the halogen atom, etc. Among these substituents, an alkyl group having 1 to 8 carbon atoms is preferred, and a methyl group is more preferred. The number of arbitrary substituents may be one or two or more. When there are two or more substituents, they may be the same or different. Specific examples of the substituted arylene group include a 2,2',3,3',5,5'-hexamethyl-4,4'-biphenylylene group, etc.

[0028] Preferred examples of the ester-type acid dianhydride represented by formula (1) include a compound (TAHQ) represented by the following formula (1-1) and a compound (TMPBP-TME) represented by the following formula (1-2), and the compound represented by the following formula (1-2) is more preferred.

[0029]

[0030] (A2) The diamine polyamic acid has structural units derived from at least two diamines as the diamine component, and one of the diamine components has a structural unit derived from (A2-1) dimer diamine. Here, the dimer diamine means an aliphatic diamine in which two terminal carboxylic acid groups (—COOH) of a cyclic or acyclic dimer acid obtained as a dimer of an unsaturated fatty acid are substituted with a primary aminomethyl group (—CH ２ —NH ２ ) or an amino group (—NH ２ ). By the polyamic acid having a structural unit derived from the dimer diamine, low dielectric characteristics can be imparted to the resulting polyimide. The dimer diamine may be used alone or in combination of two or more.

[0031] The dimer acid is a dibasic acid obtained by an intermolecular polymerization reaction of an unsaturated fatty acid. The aliphatic diamine derived from the dimer acid can be obtained, for example, by polymerizing an unsaturated fatty acid such as oleic acid, linoleic acid, or linolenic acid to form a dimer acid, reducing it, and then aminating it. Such a dimer diamine is preferably a diamine compound obtained by substituting the terminal carboxylic acid group of a dibasic acid compound in the range of 18 to 54 carbon atoms, preferably in the range of 22 to 44 carbon atoms, with a primary aminomethyl group or an amino group.

[0032] Examples of commercially available dimer diamines include “Versamine (registered trademark) 551” and “Versamine (registered trademark) 552” manufactured by Cognis Japan, and “PRIAMINE (registered trademark) 1073”, “PRIAMINE (registered trademark) 1074”, and “PRIAMINE (registered trademark) 1075” manufactured by Croda Japan.

[0033] In polyamic acid, it is preferable that (A2-1) dimeramine is present in a molar ratio of 0.3 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 (A2-1) dimeramine to the total diamine components is preferably 0.3 or more, and more preferably 0.4 or more.

[0034] Polyamic acid may also contain (A2-2) aromatic diamines as other diamine components. Examples of 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, and TFMB are preferred, with ODA being more preferred. Aromatic diamines may be used individually or in combination of two or more.

[0035] The molar ratio of diamine to ester-type acidic dianhydride [(B) / (A)] is not particularly limited, but is preferably 0.90 to 1.10, more preferably 0.95 to 1.05, even more preferably 0.97 to 1.03, and particularly preferably 0.98 to 1.02.

[0036] (B) Compounds having maleimide groups Compounds having maleimide groups are the base components of the adhesive resin composition of the present invention. By incorporating compounds having maleimide groups into the adhesive resin composition, excellent embedding and laminating properties can be imparted without impairing the low dielectric constant.

[0037] Compounds having maleimide groups are not particularly limited as long as they have one or more maleimide groups in their chemical structure. However, from the viewpoint of having a low dielectric constant while more reliably providing excellent embedding and laminating properties, compounds having a hydrocarbon structure derived from dimer acid, i.e., compounds having a maleimide group and a hydrocarbon group derived from dimer acid, are preferred. Examples of compounds having maleimide groups include resins having maleimide groups (maleimide resins).

[0038] As a compound having a maleimide group, a bismaleimide compound represented by the following formula (2) is preferred. In formula (2), R １ , R ２ , R ３ , R ４ , R ５ , R ６ , R ７ , R ８ Each of these independently represents a chain-like hydrocarbon group having 2 to 20 carbon atoms, with a preferred chain-like hydrocarbon group having 5 to 10 carbon atoms, a more preferred chain-like hydrocarbon group having 6 to 9 carbon atoms, and a particularly preferred linear hydrocarbon group having 6 to 9 carbon atoms. Furthermore, n represents an integer between 1 and 5, with a preferred integer between 1 and 3.

[0039]

[0040] Furthermore, the bismaleimide compound represented by formula (2) is more preferably the bismaleimide compound represented by the following formula (3). In formula (3), p, q, r, and s each independently represent an integer between 5 and 10, and are preferably integers between 6 and 9. Also, n represents an integer between 1 and 5, and are preferably integers between 1 and 3. The bismaleimide compound represented by formula (3) is the bismaleimide compound represented by formula (2), where R １ , R４ , R ５ , R ８ R is a linear hydrocarbon group having 5 to 10 carbon atoms. ２ , R ７ R is a linear hydrocarbon group with 8 carbon atoms. ３ , R ６ This corresponds to a bismaleimide compound, which is a linear hydrocarbon group with six carbon atoms. Furthermore, a bismaleimide compound represented by formula (3), where p, q, r, and s are all 8, is a compound having a hydrocarbon structure derived from dimer acid.

[0041]

[0042] The polyamic acid preferably contains 10% to 120% by mass, and more preferably 30% to 100% by mass, of a compound having a maleimide group, based on 100% by mass of the polyamic acid. By adjusting the amount of the compound having a maleimide group within this range, the polyamic acid can be appropriately cured to form a desired resin film.

[0043] <Synthesis of Polyamic Acids> Polyamic acids can be synthesized by known general methods. For example, polyamic acid (polyamic acid solution) can be obtained by reacting an ester-type dianhydride with a diamine in an organic solvent. The organic solvent used for polymerization of polyamic acid is not particularly limited, as long as it can dissolve the ester-type 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 acid, 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 preferred.

[0044] The molecular weight of polyamic acid can be adjusted by adjusting the molar ratio of the total moles of the ester-type dianhydride component to the total moles of the diamine component. The molecular weight (weight-average molecular weight) of polyamic acid is not particularly limited, but it is more preferable to be between 10,000 and 100,000 from the viewpoint of solubility in organic solvents. 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.

[0045] The synthesis of polyamic acids by the polyaddition reaction of ester-type 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 ester-type dianhydride and diamine in an organic solvent and mixing them. The order of addition of the ester-type 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 ester-type dianhydride may be added to the diamine solution. The ester-type 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.

[0046] 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 to 80°C. The reaction time can be arbitrarily set in the range of 1 to 72 hours, and if necessary, it may be left overnight at room temperature.

[0047] When preparing polyamic acid, the viscosity of the polyamic acid solution is preferably 500 mPa·s or higher from the viewpoint of film-forming properties. Furthermore, the solid content (concentration) of polyamic acid in the polyamic acid solution is preferably 10% by mass or higher, more preferably 15% by mass or higher, and even more preferably 20% by mass or higher. In particular, if the concentration of polyamic acid is 15% by mass or higher, the productivity of forming polyimide coating films 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.

[0048] To impart processing properties and various functionalities to polyamic acid, various organic or inorganic low-molecular-weight or high-molecular-weight compounds may be blended into the polyamic acid solution. For example, the polyamic acid composition may contain dyes, surfactants, leveling agents, plasticizers, fine particles, sensitizers, silane coupling agents, etc. The fine particles may be either organic or inorganic, and may have a porous or hollow structure.

[0049] <Resin Film> By applying the adhesive resin composition of the present invention onto a substrate and drying the resulting coating film, a resin film having an adhesive resin layer on the substrate can be formed. When using a resin film, the adhesive layer can be formed by laminating the adhesive resin layer of the resin film onto the adherend and then peeling off the substrate, which is the support. The substrate is not particularly limited, but examples include polyethylene terephthalate film (PET film) and polyethylene naphthalate film. The surface of the substrate may be treated with a release agent.

[0050] The thickness of the adhesive resin layer is not particularly limited, but is preferably 10 μm to 200 μm, and more preferably 20 μm to 100 μm. The thickness of the substrate is not particularly limited, but is preferably 10 μm to 1600 μm, and more preferably 25 μm to 400 μm.

[0051] Examples of coating devices for applying the adhesive resin composition onto a substrate include bar coaters, curtain coaters, spray coaters, roll coaters, and screen printing machines. When drying the coated film formed on the substrate, the drying temperature is preferably 60°C to 200°C, and more preferably 100°C to 160°C. The drying time is preferably 30 seconds to 1200 seconds, and more preferably 180 seconds to 800 seconds. Furthermore, when dehydrating and ring-closing the coated film after drying by heating to form a polyimide, the heat treatment temperature is preferably 150°C to 300°C, and more preferably 180°C to 250°C. The heat treatment time is preferably 60 seconds to 1800 seconds, and more preferably 300 seconds to 1500 seconds.

[0052] <Copper foil coated with resin> The copper foil coated with resin of the present invention is obtained by laminating an adhesive resin layer of the resin film described above onto copper foil. To further improve insulation, a three-layer structure may be formed by sequentially laminating a polyimide film, which is made by polyimidizing the adhesive resin composition described above, with the adhesive resin layer. With such a copper foil coated with resin, it is possible to build up another wiring on the wiring of a wiring board via an insulating layer. The copper foil may be laminated on one side of the resin film, or it may be laminated on both sides of the resin film.

[0053] <Multilayer Wiring Board> The multilayer wiring board of the present invention comprises an insulating layer formed using the above-mentioned resin film and resin-coated copper foil. For example, a double-sided copper foil substrate is made by using the above-mentioned polyimide film as a core substrate and sandwiching the adhesive resin layer surface of resin-coated copper foil from both sides. Then, a wiring pattern is formed on the copper foil by etching to produce a single-layer wiring board. Furthermore, by appropriately layering the resin film and resin-coated copper foil on top of that, a multilayer wiring board having alternating insulating layers and wiring pattern layers can be made.

[0054] The adhesive resin layer is formed by a heat-curing treatment, which involves curing the adhesive resin composition, i.e., polyimidizing the polyamic acid and then reacting it with a compound having a maleimide group to form an insulating cured resin layer. Examples of heat-curing treatments include heat-pressing treatment and heat treatment. The heat-curing treatment may be a single-step treatment or a two-step or more treatment. The temperature of the heat-curing treatment is preferably 100°C to 350°C, and more preferably 150°C to 250°C. The pressure of the heat-curing treatment is preferably 0.5 MPa to 10 MPa, and more preferably 3 MPa to 5 MPa. The duration of the heat-curing treatment is preferably 0.2 hours to 3 hours, and more preferably 0.5 hours to 1 hour.

[0055] <Coil Structure> The coil structure of the present invention comprises an insulating layer formed using the resin film described above. Such a coil structure can be manufactured by the same method as the multilayer wiring board described above. That is, the coil structure can be manufactured by using a wiring board having coil-shaped wiring as a single-layer wiring board.

[0056] <Magnetic Device> The magnetic device of the present invention comprises an insulating layer formed using the resin film described above. Such a magnetic device can be manufactured by the same method as the multilayer wiring substrate described above. By using a wiring substrate having coil-shaped wiring as a single-layer wiring substrate, a coil structure can be manufactured. Then, by providing a known magnetic material such as ferrite on this coil structure, a magnetic device can be manufactured.

[0057] Next, embodiments of the present invention will be described, but the present invention is not limited to these examples unless it exceeds the spirit of the invention.

[0058] <Examples 1-3, Comparative Examples 1-2> (Synthesis of Polyamic Acid) 120.2 g of dimer amine ("PRIAMINE® 1075", manufactured by Croda Japan Co., Ltd.), 15.0 g of aromatic diamine (4,4-oxydianiline), and 750.8 g of organic solvent (NMP) were placed in a separable flask and heated to 50°C to dissolve the diamine. Next, 186.1 g of ester-type acidic dianhydride (TMPBP-TME, manufactured by Honshu Chemical Co., Ltd.) was added, and the mixture was stirred at 50°C for 3.5 hours, and then stirred at room temperature for 24 hours to prepare a polyamic acid solution (solid content 20% by mass).

[0059] (Preparation of Adhesive Resin Composition) Each component shown in Table 1 was blended in the proportions shown in Table 1 and mixed at room temperature using a three-roll mixing machine to prepare an adhesive resin composition having a predetermined component composition. A portion of the obtained adhesive resin composition was coated onto a substrate using the test specimen preparation process described later to prepare test specimens. The adhesive resin composition and test specimens were used to evaluate each of the properties shown in Table 1. The evaluation results are shown in Table 1. Note that the blending amounts of each component shown in Table 1 represent the solid content and are expressed in parts by mass.

[0060] (Preparation of test specimens) The adhesive resin composition prepared as described above was coated onto a substrate, heat-treated, and then peeled off to prepare test specimens of the cured adhesive resin composition. Substrate: PET film (38 μm thick, with release treatment) Coating method: Bar coater DRY film thickness (20 μm to 100 μm) Heat treatment: Drying at 100°C for 10 minutes in a hot air circulating drying oven, then heat-curing at 190°C for 20 minutes

[0061] <Evaluation> (1) Dielectric Constant Using the HEWLETT PACKARD impedance analyzer "4291B", the cured material of the test piece prepared above (thickness: 25 μm, length: 20 mm, width: 20 mm) was used as a sample, and measurements were taken at a measurement temperature of 25°C and a frequency of 1 MHz to measure the dielectric constant at a frequency of 1 MHz.

[0062] (2) Embedding properties The adhesive resin composition prepared as described above was applied to a PET substrate and dried at 100°C for 10 minutes. The dried resin film was vacuum-laminated so that the coated film (adhesive resin layer) overlapped a polyimide film (thickness: 25 μm, "Kapton®", manufactured by Toray DuPont), and a sheet having a laminated structure of adhesive resin layer / polyimide film / adhesive resin layer was prepared. At that time, the adhesive resin layer was laminated so that each layer was 100 μm thick. Printed circuit boards with copper wiring ("FR-4 substrate", thickness: 400 μm, conductor thickness: 70 μm) were placed on both sides of this sheet and vacuum-pressed under the conditions of (i) 150°C, 20 minutes, 0.5 MPa and (ii) 190°C, 60 minutes, 5.0 MPa. The embedding properties were evaluated by observing the cross-section between the copper wiring of this substrate according to the following criteria.

[0063] ○: Resin can be filled in the space next to the wiring. ×: Resin cannot be filled in the space next to the wiring.

[0064] (3) Volatility (amount of volatile matter) The adhesive resin composition prepared as described above was coated onto a PET substrate to a film thickness of 25 to 35 μm and dried at 100°C for 10 minutes or at 160°C for 10 minutes. The dried resin film was heated at 180°C for 10 minutes and the amount of volatile matter of the remaining solvent was determined.

[0065] (4) Lamination The adhesive resin composition prepared as described above was coated onto a PET substrate to a thickness of 25 to 35 μm and dried at 100°C for 10 minutes or at 160°C for 10 minutes. The dried resin film was vacuum laminated so that the coated film (adhesive resin layer) overlapped a Kapton film (25 μm), and the lamination properties were evaluated according to the following criteria.

[0066] ○: No lamination issues ×: Lamination failed, peeling occurred

[0067]

[0068] Details of the compounds containing a maleimide group in Table 1 are as follows: • Maleimide resin: "SLK-1500" (manufactured by Shin-Etsu Chemical Co., Ltd.), a bismaleimide compound in which p, q, r, and s are all 8 in formula (3) above.

[0069] As shown in Table 1, in Examples 1 to 3, using an adhesive resin composition containing (A) polyamic acid and (B) a compound having a maleimide group, wherein the composition contained 10% to 120% by mass of the compound having a maleimide group relative to 100% by mass of (A) polyamic acid, the resulting cured product exhibited low dielectric properties, and a resin film with excellent embedding and laminating properties was produced.

[0070] On the other hand, in Comparative Example 1, where the amount of the compound having a maleimide group exceeded 120% by mass relative to 100% by mass of polyamic acid, the adhesive resin composition could not be cured, and none of the properties could be measured or evaluated.

[0071] Furthermore, in Comparative Example 2, which did not contain a compound with a maleimide group, both the evaluation of embedding ability and the evaluation of laminating ability under drying conditions of 160°C for 10 minutes were "X". Moreover, the amount of residual solvent volatile was higher and the volatility was inferior compared to Examples 1 to 3.

[0072] The adhesive resin composition of the present invention exhibits low dielectric properties in its cured product, and furthermore, it is possible to produce a resin film using such an adhesive resin composition that has excellent embedding and laminating properties and low volatile content of residual solvent, making it highly valuable as a substrate material for high-frequency circuits.

Claims

1. An adhesive resin composition comprising (A) a polyamic acid and (B) a compound having a maleimide group, wherein the composition contains 10% by mass or more and 120% by mass or less of the compound having a maleimide group based on 100% by mass of the polyamic acid (A).

2. The adhesive resin composition according to claim 1, wherein the (A) polyamic acid is a polyaddition product of (A1) an ester-type dianhydride and (A2) at least two diamines.

3. The adhesive resin composition according to claim 2, wherein the (A1) ester-type acid dianhydride has a structure represented by the following formula (1). (In formula (1), Ar represents a substituted or unsubstituted arylene group.) 4. The adhesive resin composition according to claim 1, wherein the compound having the (B) maleimide group has a hydrocarbon structure derived from dimer acid.

5. The adhesive resin composition according to claim 1, wherein the compound having the (B) maleimide group is a bismaleimide compound represented by the following formula (2). (In formula (2), R １ , R ２ , R ３ , R ４ , R ５ , R ６ , R ７ , R ８ Each of these independently represents a chain-like hydrocarbon group with 2 to 20 carbon atoms, and n represents an integer between 1 and 5.

6. The adhesive resin composition according to claim 5, wherein the bismaleimide compound represented by formula (2) is a bismaleimide compound represented by the following formula (3). (In equation (3), p, q, r, and s each independently represent an integer between 5 and 10, and n represents an integer between 1 and 5.) 7. A resin film formed using the adhesive resin composition according to any one of claims 1 to 6.

8. A multilayer wiring board comprising an insulating layer formed using the resin film described in claim 7.

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

10. A coil structure comprising an insulating layer formed using the resin film described in claim 7.

11. A magnetic device comprising an insulating layer formed using the resin film described in claim 7.

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