Polyamic acid, polyamic acid composition, polyimide, polyimide composition, polyimide film, copper foil with resin, multilayer wiring board, coil structure, magnetic device, and insulated wire

Abstract

This polyamic acid is a polyaddition reaction product of (A) an acid dianhydride and (B) a diamine, wherein (B1) a dimer diamine is contained in a molar ratio of 0.2 or more with respect to the total diamine components, and a fluorine atom is contained in one molecule of a raw material of the polyamic acid.

Description

Polyamic acid, polyamic acid composition, polyimide, polyimide composition, polyimide film, copper foil with resin, multilayer wiring board, coil structure, magnetic device, and insulated wire

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

[0002] Since polyimide is excellent in heat resistance, mechanical properties, and insulation properties, it is widely used as an insulating material constituting electronic devices. However, general polyimide has high dielectric properties such as dielectric constant, which causes a delay in signal transmission and becomes an obstacle to high-speed operation. For such high-frequency applications, there is an increasing demand for polyimide having low dielectric properties. For example, Patent Document 1 discloses that a polyimide prepared using an aromatic diamine having a specific structure and a tetracarboxylic dianhydride exhibits a low dielectric constant and excellent heat resistance.

[0003] Also, a method of reducing the dielectric constant of polyimide by introducing a fluorene skeleton into the diamine component to reduce the imide group concentration and the polarity of the whole molecule is known. For example, Patent Document 2 discloses that a polyimide using trimellitic anhydride chloride as an acid anhydride and 9,9-bis(4-aminophenyl)fluorene as a diamine exhibits high heat resistance and a low relative dielectric constant.

[0004] JP-A-10-152559 JP-A-2005-298625

[0005] On the other hand, workability during the production of a multilayer wiring board or the like is also required for polyimide. Specifically, the embedding property of wiring with polyimide is required. Also, it is desirable that the polyimide film used for embedding can be easily obtained. Specifically, solubility of polyimide in an organic solvent is required. However, the polyimides described in Patent Documents 1 and 2 cannot satisfy these requirements.

[0006] The present invention aims to provide a polyamic acid that exhibits excellent embedding properties for wiring using polyimide and excellent solubility of polyimide in organic solvents, as well as a polyamic acid composition, polyimide, polyimide composition, polyimide film, resin-coated copper foil, multilayer wiring board, coil structure, magnetic device, and insulated wire using the same.

[0007] The present invention provides the following polyamic acid, polyamic acid composition, polyimide, polyimide composition, polyimide film, resin-coated copper foil, multilayer wiring board, coil structure, magnetic device, and insulated wire. [1] A polyamic acid which is a polyaddition reaction product of (A) an acid dianhydride and (B) a diamine, wherein (B1) dimeramine is contained in a molar ratio of 0.2 or more relative to the total diamine component, and a fluorine atom is contained in one molecule of the raw material of the polyamic acid. [2] A polyamic acid according to [1], 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.) [3] A polyamic acid according to [1] or [2], wherein the (B) diamine comprises (B2) an aromatic diamine, and the (B2) aromatic diamine comprises (B21) a fluorine-containing aromatic diamine containing fluorine in one molecule. [4] A polyamic acid composition comprising the polyamic acid according to any one of [1] to [3] and (C) an organic solvent. [5] A polyimide obtained by imidizing the polyamic acid according to any one of [1] to [3]. [6] A polyimide composition obtained by imidizing the polyamic acid according to any one of [1] to [3]. [7] A polyimide film comprising a polyimide obtained by imidizing the polyamic acid according to any one of [1] to [3]. [8] A resin-coated copper foil comprising the polyimide film according to [7] and a copper foil laminated on the polyimide film. [9] A multilayer wiring board comprising an insulating layer formed using the polyimide film described in [7].

[10] A coil structure comprising an insulating layer formed using the polyimide film described in [7].

[11] A magnetic device comprising an insulating layer formed using the polyimide film described in [7].

[12] An insulated wire comprising an insulating layer made of the polyimide described in [5] and a wire covered with the insulating layer.

[0010] According to one aspect of the present invention, a polyamic acid having excellent embedding properties for wiring by polyimide and excellent solubility of polyimide in organic solvents, as well as a polyamic acid composition, polyimide, polyimide composition, polyimide film, resin-coated copper foil, multilayer wiring board, coil structure, magnetic device, and insulated wire using the same can be provided.

[0011] [Polyamic Acid] The polyamic acid according to this embodiment is a polyamic acid obtained by a polyaddition reaction between (A) an acidic dianhydride and (B) a diamine. It contains (B1) dimeramine in a molar ratio of 0.2 or more relative to the total diamine components. Furthermore, one molecule of the raw material for the polyamic acid contains a fluorine atom.

[0012] According to this embodiment, a polyamic acid is obtained that exhibits excellent embedding properties for polyimide wiring and excellent solubility of polyimide in organic solvents. The reason for this is not entirely clear, but the inventors speculate as follows. That is, the polyamic acid according to this embodiment contains (B1) dimeramine in a molar ratio of 0.2 or more relative to the total diamine components. Low dielectric properties are exhibited due to the dimer skeleton, and the inclusion of a certain amount of dimeramine as a diamine component improves the embedding properties for polyimide wiring. Furthermore, in this embodiment, the inclusion of a fluorine atom in one molecule of the raw material for the polyamic acid improves the solubility of polyimide in organic solvents. The inventors speculate that the effects of the present invention described above are achieved in this way.

[0013] (Component (A)) The polyamic acid according to this embodiment uses (A) an acid dianhydride as one of its raw materials. Known acid dianhydrides can be used as appropriate. Examples of acid dianhydride components include 3,3',4,4'-biphenyltetracarboxylic acid dianhydride (BTDA), pyromellitic acid dianhydride (PMDA), 4,4'-(hexafluoroisopropylidene)diphthalic acid anhydride (6FDA), and ester-type acid dianhydrides having an ester bond in the molecule. Furthermore, from the viewpoint of containing a fluorine atom in one molecule of at least one raw material of the polyamic acid, it is preferable to use a fluorine-containing acid dianhydride containing a fluorine atom in one molecule as (A) acid dianhydride, and it is preferable to use 4,4'-(hexafluoroisopropylidene)diphthalic acid anhydride (6FDA). When using this fluorine-containing acid dianhydride, it is preferable that the fluorine-containing acid dianhydride is contained in a molar ratio of 0.2 or more (more preferably 0.5 or more) relative to the total acid dianhydride components. Furthermore, 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 dianhydride, and more preferably an aromatic tetracarboxylic dianhydride. The molecule may have one or more ester bonds, preferably one to three, and more preferably one or two. The acid dianhydride may be used alone, or two or more may be used in combination.

[0014] 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.

[0015]

[0016] In formula (1), examples of unsubstituted arylene groups in Ar include o-phenylene, m-phenylene, p-phenylene, 2,6-naphthylene, and 4,4'-biphenylylene. Among these, p-phenylene, 2,6-naphthylene, or 4,4'-biphenylylene are preferred.

[0017] 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.

[0018] 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.

[0019]

[0020] (Component (B)) The polyamic acid according to this embodiment uses (B) diamine as one of the raw materials. Known diamines 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 ２This 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.

[0021] 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, which are then reduced and aminated. 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.

[0022] Commercially available dimeramines include "Versamin® 551" and "Versamin® 552" from Cognics Japan, and "PRIAMINE® 1073," "PRIAMINE® 1074," and "PRIAMINE® 1075" from Croda Japan.

[0023] Furthermore, in the polyamic acid according to this embodiment, (B1) dimeramine is contained 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 more, and more preferably 0.4 or more.

[0024] The polyamic acid according to this embodiment preferably contains (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, diaminodiphenyl sulfone, 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. Furthermore, from the viewpoint of including a fluorine atom in one molecule of at least one of the raw materials of the polyamic acid, it is preferable to use a fluorine-containing aromatic diamine (B21) containing fluorine in one molecule as the (B2) aromatic diamine, and it is preferable to use 3,3'-bistrifluoromethyl-4,4'-diaminobiphenyl (TFMB). When using this (B21) fluorine-containing aromatic diamine, it is preferable that the (B21) fluorine-containing aromatic diamine is included in a molar ratio of 0.2 or more (more preferably 0.5 or more) relative to the total diamine components.

[0025] 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.

[0026] (Component (C)) The polyamic acid according to 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.

[0027] 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.

[0028] 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.

[0029] 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.

[0030] When preparing the polyamic acid composition according to this embodiment, the viscosity of the solution is preferably 500 mPa·s or more from the viewpoint of film-forming properties. Furthermore, the concentration of polyamic acid in the polyamic acid composition according to this embodiment is preferably 10% by mass or more, more preferably 15% by mass or more, and even more preferably 25% by mass or more. In particular, if the concentration of polyamic acid is 15% by mass or more, 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 less, and even more preferably 30% by mass or less, from the viewpoint of sufficiently dissolving the polyamic acid in the organic solvent.

[0031] To impart processing properties or various functionalities to polyamic acid and polyimides formed using said polyamic acid, various organic or inorganic low-molecular-weight or high-molecular-weight compounds may be blended into the polyamic acid composition. For example, the polyamic acid composition may contain solvent-soluble polyimide resin, flame retardants, dyes, surfactants, leveling agents, plasticizers, fine particles, sensitizers, or silane coupling agents. The fine particles may be either organic or inorganic, and may have a porous or hollow structure. Furthermore, after polyimidization of the polyamic acid, some of the amino groups may be maleimidized.

[0032] [Polyimide, Polyimide Composition, and Polyimide Film] The polyimide according to this embodiment is a polyimide obtained by imidizing the polyamic acid according to this embodiment as described above. The polyimide composition according to this embodiment is a polyimide composition obtained by imidizing the polyamic acid according to this embodiment as described above. 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. The method for dehydrating and cyclizing (imidizing) can be a known method such as thermal imidization, which dehydrates and cyclizes by heating, or chemical imidization, which chemically cyclizes using a known dehydration and cyclization catalyst.

[0033] In the case of thermal imidation, the heating temperature is preferably 120°C to 350°C, and more preferably 150°C to 250°C. In the case of chemical imidation, for example, pyridine, triethylamine, or acetic anhydride can be used as the dehydration and ring-closing catalyst. In this case, the reaction temperature can be selected from any temperature between 20°C and 180°C, but it is preferably 150°C or lower. Imidation may be carried out in air, under reduced pressure, or in an inert gas such as nitrogen, but in order to obtain a highly transparent polyimide film, it is preferable to carry it out under reduced pressure or in an inert gas such as nitrogen.

[0034] The molecular weight (weight-average molecular weight) of the polyimide is not particularly limited, but it is preferably between 10,000 and 100,000 from the viewpoint of low dielectric properties, solubility in organic solvents, and film-forming properties of the resulting polyimide. The weight-average molecular weight of the polyimide can be determined, for example, from the value converted to standard polystyrene by gel filtration chromatography (GPC) measurement.

[0035] The polyimide film according to this embodiment contains the polyimide obtained as described above. The method for producing such a polyimide 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 (imidize), or coating a solution in which soluble polyimide obtained by converting polyamic acid to polyimide is dissolved in an organic solvent onto a substrate in a film-like manner, 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.

[0036] The thickness of the polyimide film is not particularly limited and can be appropriately selected depending on the application. The thickness of the polyimide 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.

[0037] [Applications of Polyimide] The polyimide and polyimide compositions 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 polyimide 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).

[0038] 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 listed below. (Component (A)) Ester-type dianhydride: 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) Fluorine-containing dianhydride: 4,4'-(Hexafluoroisopropylidene)diphthalic acid anhydride (6FDA) Dianhydride: 3,3',4,4'-Biphenyltetracarboxylic acid dianhydride (BTDA) (Component (B1)) Dimer amine: PRIAMINE 1075, manufactured by Croda Japan Co., Ltd. (Component (B2)) Aromatic diamine: 4,4'-Oxydianiline (ODA) (Component (B21)) Fluorine-containing aromatic diamine: 3,3'-bistrifluoromethyl-4,4'-diaminobiphenyl (TFMB) (Component (C)) Organic solvent: N-methyl-2-pyrrolidone (NMP)

[0039] [Example 1] 1.6 parts by mass of a dimer diamine, 2.3 parts by mass of a fluorine-containing aromatic diamine, and 30 parts by mass of an organic solvent were charged into a flask to dissolve the diamine. Next, 3.1 parts by mass of an ester-type acid dianhydride and 1.6 parts by mass of an acid dianhydride were added, and the mixture was stirred at 80 °C for 5 hours to prepare a polyamic acid composition. Next, 0.09 parts by mass of γ-valerolactone and 0.14 parts by mass of pyridine were added to the obtained polyamic acid composition, and the mixture was stirred at 150 °C for 10 to 24 hours to prepare a polyimide composition.

[0040] [Examples 2 and 3] Polyamic acid compositions and polyimide compositions were obtained in the same manner as in Example 1, except that the materials were blended according to the compositions shown in Table 1.

[0041] [Comparative Examples 1 and 2] Polyamic acid compositions and polyimide compositions were obtained in the same manner as in Example 1, except that the materials were blended according to the compositions shown in Table 1.

[0042] [Comparative Example 3] 4.0 parts by mass of a dimer diamine, 0.5 parts by mass of an aromatic diamine, and 30 parts by mass of an organic solvent were charged into a flask to dissolve the diamine. Next, 6.2 parts by mass of an ester-type acid dianhydride was added, and the mixture was stirred at 80 °C for 24 hours to prepare a polyamic acid composition. Next, 0.09 parts by mass of γ-valerolactone and 0.14 parts by mass of pyridine were added to the obtained polyamic acid composition, and the mixture was stirred at 150 °C for 10 to 24 hours to prepare a polyimide composition. However, insoluble matter occurred in the obtained polyimide composition.

[0043] [Evaluation of Polyimide] Polyimide was evaluated (dielectric constant, dielectric strength, elongation at break, embedding ability, solubility) using the following method. The results obtained are shown in Table 1. Table 1 also shows the molar ratio in component (A), the molar ratio in component (B), the molar ratio of diamine to acidic dianhydride [(B) / (A)], and the presence or absence of fluorine atoms in one molecule of the raw material for each example. (1) Dielectric constant First, test specimens were prepared as follows. That is, the polyimide composition was applied to a substrate (PET film, thickness: 38 μm, with release treatment) using a bar coater, and heat treatment was performed at 100°C for 10 minutes, and then at 190°C for 20 minutes to prepare test specimens of a predetermined size. However, for Comparative Example 3, a polyamic acid composition was used to prepare the test specimens. The obtained test specimen (thickness: 25 μm, length: 20 mm, width: 20 mm) was measured using an impedance analyzer under the conditions of a measurement temperature of 25°C and a frequency of 1 MHz to measure the dielectric constant at a frequency of 1 MHz. The dielectric constant was then evaluated according to the following criteria: A: Dielectric constant is less than 2.8. B: Dielectric constant is 2.8 or more and less than 2.9. C: Dielectric constant is 2.9 or more. (2) Except for the size of the dielectric constant test specimen, a test specimen of the specified size was prepared in the same manner as the dielectric constant test specimen in (1). The obtained test specimen (thickness: 25 μm, length: 50 mm, width: 50 mm) was measured for dielectric strength under the conditions of a measurement temperature of 25°C to measure the voltage leading to dielectric breakdown (dielectric breakdown strength). The dielectric strength was then evaluated according to the following criteria: A: The voltage leading to dielectric breakdown is 280 kV / mm or more. C: The voltage leading to dielectric breakdown is less than 280 kV / mm. (3) A test specimen of the specified size was prepared in the same manner as the dielectric constant test specimen in (1), except for the size of the elongation at break test specimen. The obtained test specimen (thickness: 25 μm, gauge length: 40 mm, width: 3 mm) was measured using an autograph at a measurement temperature of 25 °C and a tensile speed of 0.5 mm / min to measure the elongation at break. The elongation at break was then evaluated according to the following criteria: A: Elongation at break is 10% or more. B: Elongation at break is 5% or more and less than 10%. C: Elongation at break is less than 5%. (4) Embedding properties First, a test sheet was prepared as follows.That is, on a substrate (PET film, thickness: 38 μm, with release treatment), a polyimide composition was applied using a bar coater and dried under the conditions of 100 °C for 10 minutes to obtain a dried film. This dried film was vacuum laminated to a Kapton (registered trademark) film (thickness: 25 μm) to produce a test sheet with a polyimide / Kapton / polyimide layer structure. At this time, a plurality of dried films were laminated so that the thickness of each polyimide layer would be 50 to 80 μm. However, for Comparative Example 3, a test sheet was produced using a polyamic acid composition. On the top and bottom of the obtained test sheet, FR-4 substrates with copper wiring (substrate thickness: 400 μm, conductor thickness: 35 μm) were arranged and vacuum pressed under the conditions of (i) 150 °C, 20 minutes, and 0.5 MPa, and (ii) 190 °C, 60 minutes, and 3.3 MPa. Then, the cross-section between the copper wirings of this substrate was observed, and the embedding property was evaluated according to the following criteria. A: The polyimide can be filled between the copper wirings of the substrate. B: There are parts where the polyimide cannot be filled between the copper wirings of the substrate, but there are no practical problems. C: The polyimide cannot be filled on the upper part or side surface of the wiring. (5) Solubility Using the obtained polyimide composition as a sample, the presence or absence of insoluble matter when polyimidization proceeded was confirmed. Then, the solubility was evaluated according to the following criteria. A: No insoluble matter has occurred. C: Insoluble matter has occurred.

[0044]

[0045] As is clear from the results shown in Table 1, it was confirmed that for the polyimides of the present invention (Examples 1 to 3), all the results of dielectric constant, breakdown voltage, elongation at break, embedding property, and solubility were good. Therefore, according to the polyimide of the present invention, it was confirmed that the embedding property of the wiring by the polyimide and the solubility of the polyimide in an organic solvent are excellent.

Claims

A polyamic acid is a polyaddition product of (A) an acidic dianhydride and (B) a diamine, The (B1) dimer amine is contained in a molar ratio of 0.2 or more relative to the total diamine components. The raw material for the polyamic acid contains a fluorine atom in one molecule. Polyamic acid. 　 In the polyamic acid according to claim 1, The (A) acid dianhydride has the structure shown in the following formula (1): Polyamic acid. (In formula (1), Ar represents a substituted or unsubstituted arylene group.) 　 In the polyamic acid according to claim 1 or claim 2, The (B) diamine includes (B2) aromatic diamine, The (B2) aromatic diamine includes (B21) a fluorine-containing aromatic diamine that contains fluorine in one molecule. Polyamic acid. 　 A polyamic acid according to claim 1 or claim 2, and (C) an organic solvent, comprising Polyamic acid composition. 　 Obtained by imidizing the polyamic acid described in claim 1 or claim 2, Polyimide. 　 Obtained by imidizing the polyamic acid described in claim 1 or claim 2, Polyimide composition. 　 The polyimide includes one obtained by imidizing the polyamic acid described in claim 1 or claim 2. Polyimide film. 　 The polyimide film according to claim 7 and the copper foil laminated on the polyimide film, Copper foil coated with resin. 　 The insulating layer is formed using the polyimide film described in claim 7. Multilayer wiring board. 　 The insulating layer is formed using the polyimide film described in claim 7. Coil structure. 　 The insulating layer is formed using the polyimide film described in claim 7. Magnetic device. 　 The invention comprises an insulating layer made of polyimide as described in claim 5, and an electric wire covered with the insulating layer, Insulated wire.

Images