Polyamide acid, polyimide precursor composition, polyimide resin, wiring circuit board, and electronic device

Abstract

This polyamide acid is a reaction product of an acid dianhydride component and a diamine component. The acid dianhydride component contains biphenyl tetracarboxylic dianhydride. The diamine component does not contain a fluorine atom or oxydianiline, and contains 4-aminophenyl-4-aminobenzoate.

Description

Polyamic acid, polyimide precursor composition, polyimide resin, wiring circuit board, and electronic device

[0001] The present invention relates to a polyamic acid, a polyimide precursor composition, a polyimide resin, a wiring circuit board, and an electronic device.

[0002] BACKGROUND ART Conventionally, a laminate in which a metal substrate, an insulating layer, a wiring layer, and a coating layer are laminated has been known as a wired circuit board used in an electronic device.

[0003] The insulating layer and the covering layer used in such a wired circuit board are made of, for example, a polyimide resin, and the polyimide resin is formed using a polyamic acid as a material (see, for example, Patent Document 1 below). The polyamic acid described in Patent Document 1 contains fluorine atoms, so that a polyimide resin with low water absorption can be formed, and wired circuit boards using such a polyimide resin have excellent reliability.

[0004] JP 2013-100441 A

[0005] On the other hand, in recent years, there has been a demand for polyimide resins that do not contain fluorine atoms in order to reduce the environmental impact.

[0006] That is, there is a demand for polyimide resins that have low water absorption and can reduce the environmental load, and further, there is a demand for polyamic acids that form such polyimide resins.

[0007] The present invention provides a polyamic acid, a polyimide precursor composition, a polyimide resin, a wiring circuit board, and an electronic device that have low water absorption and can reduce the environmental load.

[0008] The present invention [1] relates to a reaction product of an acid dianhydride component and a diamine component, wherein the acid dianhydride component contains biphenyltetracarboxylic dianhydride, and the diamine component contains a polyamic acid that does not contain a fluorine atom or oxydianiline but contains 4-aminophenyl-4-aminobenzoate.

[0009] The present invention [2] includes the polyamic acid according to [1], in which the diamine component further includes p-phenylenediamine, and the total content of the 4-aminophenyl-4-aminobenzoate and the p-phenylenediamine in the diamine component is 90 mol % or more.

[0010] The present invention [3] includes the polyamic acid according to [2], wherein the diamine component comprises the 4-aminophenyl-4-aminobenzoate and the p-phenylenediamine.

[0011] The present invention [4] includes the polyamic acid according to [2] or [3], in which the content of the p-phenylenediamine in the diamine component is 50 mol % or more.

[0012] The present invention [5] includes a polyimide precursor composition containing the polyamic acid according to any one of [1] to [4], a photosensitizer, and a development accelerator.

[0013] The present invention [6] includes the polyimide precursor composition according to [5], wherein the photosensitizer is a pyridine-based photosensitizer.

[0014] The present invention [7] includes the polyimide precursor composition according to [5] or [6], wherein the development accelerator is a 4-hydroxybenzoic acid.

[0015] The present invention [8] includes a polyimide resin formed from the polyimide precursor composition according to any one of [5] to [7].

[0016] The present invention [9] includes a printed circuit board containing the polyimide resin according to [8].

[0017] The present invention

[10] includes an electronic device including the printed circuit board according to [9].

[0018] The polyamic acid of the present invention is a reaction product of an acid dianhydride component and a diamine component, in which the acid dianhydride component contains biphenyltetracarboxylic dianhydride, and the diamine component does not contain fluorine atoms or oxydianiline but contains 4-aminophenyl-4-aminobenzoate, thereby forming a polyimide resin that has low water absorption and can reduce the environmental impact.

[0019] The polyimide precursor composition of the present invention contains the polyamic acid of the present invention, and therefore can form a polyimide resin that has low water absorption and can reduce the environmental load.

[0020] The polyimide resin of the present invention is formed from the polyimide precursor composition of the present invention, and therefore has low water absorption and can reduce the environmental load.

[0021] The wired circuit board of the present invention contains the polyimide resin of the present invention, and therefore has reduced environmental impact and excellent reliability.

[0022] The electronic device of the present invention includes the wired circuit board of the present invention, which reduces the environmental load and has excellent reliability.

[0023] 1A to 1E show an example of a method for forming a coating layer using a polyimide resin formed from a polyimide precursor composition according to one embodiment of the present invention, where Fig. 1A shows a lamination step, Fig. 1B shows an etching step, Fig. 1C shows a coating step, Fig. 1D shows an exposure step, and Fig. 1E shows a development step.

[0024] 1. Polyamic Acid The polyamic acid of the present invention is a polyimide precursor, which is a reaction product of an acid dianhydride component and a diamine component.

[0025] <Acid Dianhydride Component> The acid dianhydride component includes biphenyltetracarboxylic dianhydride, preferably biphenyltetracarboxylic dianhydride.

[0026] Examples of biphenyltetracarboxylic dianhydrides include 3,3'-4,4'-biphenyltetracarboxylic dianhydride, 2,2'-3,3'-biphenyltetracarboxylic dianhydride, 2,3,3',4'-biphenyltetracarboxylic dianhydride, and 3,3',4,4'-diphenylethertetracarboxylic dianhydride. Preferably, 3,3'-4,4'-biphenyltetracarboxylic dianhydride is used.

[0027] The biphenyltetracarboxylic dianhydrides may be used alone or in combination of two or more.

[0028] The molar fraction of biphenyltetracarboxylic dianhydride in the acid dianhydride component is, for example, 50 mol% to 100 mol%, preferably 70 mol% to 100 mol%, more preferably 80 mol% to 100 mol%, even more preferably 90 mol% to 100 mol%, particularly preferably 95 mol% to 100 mol%, and most preferably 100 mol%.

[0029] The molar fraction of biphenyltetracarboxylic dianhydride in the acid dianhydride component is, for example, 50 mol% or more, preferably 70 mol% or more, more preferably 80 mol% or more, even more preferably 90 mol% or more, particularly preferably 95 mol% or more, and most preferably 100 mol%.

[0030] The acid dianhydride component may contain other acid dianhydride components in addition to biphenyltetracarboxylic dianhydride.

[0031] Examples of other acid dianhydride components include tetracarboxylic dianhydrides (excluding biphenyltetracarboxylic dianhydride). Examples of tetracarboxylic dianhydrides (excluding biphenyltetracarboxylic dianhydride) include aliphatic tetracarboxylic dianhydrides and aromatic tetracarboxylic dianhydrides (excluding biphenyltetracarboxylic dianhydride).

[0032] Examples of the aliphatic tetracarboxylic dianhydride include cyclopentanetetracarboxylic dianhydride and tricarboxycyclopentylacetic dianhydride.

[0033] Examples of aromatic tetracarboxylic dianhydrides (excluding biphenyltetracarboxylic dianhydride) include benzenetetracarboxylic dianhydride, benzophenonetetracarboxylic dianhydride, biphenylsulfonetetracarboxylic dianhydride, and naphthalenetetracarboxylic dianhydride.

[0034] Examples of benzenetetracarboxylic dianhydrides include benzene-1,2,4,5-tetracarboxylic dianhydride (also known as pyromelotic dianhydride). Examples of benzophenone tetracarboxylic dianhydrides include 3,3'-4,4'-benzophenone tetracarboxylic dianhydride. Examples of biphenylsulfone tetracarboxylic dianhydride include 3,3',4,4'-biphenylsulfone tetracarboxylic dianhydride. Examples of naphthalene tetracarboxylic dianhydrides include 2,3,6,7-naphthalene tetracarboxylic dianhydride, 1,2,5,6-naphthalene tetracarboxylic dianhydride, 1,2,4,5-naphthalene tetracarboxylic dianhydride, and 1,4,5,8-naphthalene tetracarboxylic dianhydride.

[0035] The other acid dianhydride components may be used alone or in combination of two or more.

[0036] When the acid dianhydride component contains another acid dianhydride component, the molar fraction of the other acid dianhydride component in the acid dianhydride component is, for example, 0 mol% to 50 mol%, preferably 0 mol% to 30 mol%, more preferably 0 mol% to 20 mol%, even more preferably 0 mol% to 10 mol%, particularly preferably 0 mol% to 5 mol%, and most preferably 0 mol% to 1 mol%.

[0037] When the acid dianhydride component contains other acid dianhydride components, the molar fraction of the other acid dianhydride components in the acid dianhydride component is, for example, less than 50 mol%, preferably 30 mol% or less, more preferably 20 mol% or less, even more preferably 10 mol% or less, particularly preferably 5 mol% or less, and most preferably 1 mol% or less.

[0038] The acid dianhydride component contains biphenyltetracarboxylic dianhydride. Preferably, from the viewpoint of mechanical strength, it contains 3,3'-4,4'-biphenyltetracarboxylic dianhydride. More preferably, it contains 3,3'-4,4'-biphenyltetracarboxylic dianhydride. Note that 3,3'-4,4'-biphenyltetracarboxylic dianhydride is sometimes abbreviated simply as BPDA.

[0039] <Diamine Component> The diamine component contains 4-aminophenyl-4-aminobenzoate and does not contain a fluorine atom or oxydianiline.

[0040] Specifically, the diamine component contains 4-aminophenyl-4-aminobenzoate, which is an aromatic diamine represented by the following formula (1) in which Y is —COO—. 4-aminophenyl-4-aminobenzoate may also be abbreviated simply as APAB.

[0041]

[0042] If the diamine component contains 4-aminophenyl-4-aminobenzoate, thermal expansion can be suppressed. In other words, the thermal expansion coefficient can be lowered. Furthermore, thermal expansion upon moisture absorption can be suppressed. In other words, the moisture absorption thermal expansion coefficient can be lowered.

[0043] The molar fraction of 4-aminophenyl-4-aminobenzoate in the diamine component is, for example, 1 mol% to 90 mol%, preferably 5 mol% to 70 mol%, more preferably 10 mol% to 50 mol%, and even more preferably 20 mol% to 40 mol%.

[0044] The molar fraction of 4-aminophenyl-4-aminobenzoate in the diamine component is, for example, 1 mol% or more, preferably 5 mol% or more, more preferably 10 mol% or more, even more preferably 20 mol% or more, and for example, 90 mol% or less, preferably 70 mol% or less, more preferably 50 mol% or less, even more preferably 40 mol% or less.

[0045] When the molar fraction of 4-aminophenyl-4-aminobenzoate in the diamine component is within the above range, thermal expansion can be suppressed. In other words, the thermal expansion coefficient can be reduced. Furthermore, thermal expansion upon moisture absorption can be suppressed. In other words, the moisture absorption thermal expansion coefficient can be reduced. In other words, the water absorption of the polyimide resin can be reduced.

[0046] The diamine component may contain other diamine components in addition to 4-aminophenyl-4-aminobenzoate. The diamine component preferably contains other diamine components. However, the other diamine components also do not contain fluorine atoms or oxydianiline.

[0047] Examples of the other diamine components include aromatic diamines having multiple aromatic rings (excluding 4-aminophenyl-4-aminobenzoate, oxydianiline, and those containing a fluorine atom), and aromatic diamines having a single aromatic ring (excluding those containing a fluorine atom).

[0048] Examples of aromatic diamines having a plurality of aromatic rings (excluding 4-aminophenyl-4-aminobenzoate, oxydianiline, and those containing fluorine atoms) include 4,4'-diaminodiphenyl in which Y is a single bond, bis(4-aminophenyl)sulfide in which Y is -S-, and bis(4-aminophenyl)sulfide in which Y is -CH(CH ３ 4,4'-diaminodiphenylethane where Y is —C(CH ３ ) ２ -, 4,4'-diaminobenzophenone where Y is -CO-, 4,4'-diaminophenyleneamine where Y is -NH-, and 4,4'-diaminobenzanilide where Y is -NHCO-.

[0049] The aromatic diamine having multiple aromatic rings does not include oxydianiline. Specifically, the aromatic diamine having multiple aromatic rings does not include oxydianiline in which, in the above formula (1), Y is —O— (ether bond). Examples of oxydianiline include 3,4′-oxydianiline (also known as 3,4′-diaminodiphenyl tail) and 4,4′-oxydianiline (also known as 4,4′-diaminodiphenyl tail). 4,4′-oxydianiline is sometimes abbreviated simply as ODA.

[0050] Oxydianiline has two aromatic rings bonded by an ether bond, which gives it high water absorption. In other words, if the diamine component does not contain oxydianiline, the water absorption of the polyimide resin can be further reduced.

[0051] The aromatic diamine having multiple aromatic rings does not contain a fluorine atom. Specifically, the aromatic diamine having multiple aromatic rings does not contain 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl. 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl is sometimes abbreviated simply as TFMB.

[0052] If the diamine component does not contain a fluorine atom, the environmental load can be reduced.

[0053] Examples of aromatic diamines having a single aromatic ring (excluding those containing a fluorine atom) include phenylenediamine, dimethylbenzenediamine, and ethylmethylbenzenediamine. From the viewpoint of mechanical strength, phenylenediamine is preferred.

[0054] Examples of phenylenediamines include o-phenylenediamine, m-phenylenediamine, and p-phenylenediamine. Preferably, p-phenylenediamine is used. p-Phenylenediamine is sometimes simply abbreviated as PDA.

[0055] The other diamine components may be used alone or in combination of two or more.

[0056] The molar fraction of the other diamine component in the diamine component is, for example, 10 mol% to 99 mol%, preferably 30 mol% to 95 mol%, more preferably 50 mol% to 90 mol%, and even more preferably 60 mol% to 80 mol%.

[0057] The molar fraction of the other diamine component in the diamine component is, for example, 10 mol% or more, preferably 30 mol% or more, more preferably 50 mol% or more, even more preferably 60 mol% or more, and for example, 99 mol% or less, preferably 95 mol% or less, more preferably 90 mol% or less, even more preferably 80 mol% or less.

[0058] When the molar fraction of the other diamine component in the diamine component is within the above range, the content of 4-aminophenyl-4-aminobenzoate can be adjusted to an appropriate range, and thermal expansion can be suppressed. In other words, the thermal expansion coefficient can be reduced. Furthermore, expansion upon moisture absorption can be suppressed. In other words, the moisture absorption thermal expansion coefficient can be reduced. In other words, the water absorption of the polyimide resin can be reduced.

[0059] The diamine component is free of fluorine atoms and oxydianiline and includes 4-aminophenyl-4-aminobenzoate. The diamine component is preferably free of fluorine atoms and oxydianiline and includes 4-aminophenyl-4-aminobenzoate and p-phenylenediamine. The diamine component more preferably consists of 4-aminophenyl-4-aminobenzoate and p-phenylenediamine.

[0060] When the diamine component contains p-phenylenediamine, the molar fraction of p-phenylenediamine in the diamine component is, for example, 10 mol% to 99 mol%, preferably 30 mol% to 95 mol%, more preferably 50 mol% to 90 mol%, and even more preferably 60 mol% to 80 mol%.

[0061] When the diamine component contains p-phenylenediamine, the molar fraction of p-phenylenediamine in the diamine component is, for example, 10 mol% or more, preferably 30 mol% or more, more preferably 50 mol% or more, even more preferably 60 mol% or more, and for example, 99 mol% or less, preferably 95 mol% or less, more preferably 90 mol% or less, even more preferably 80 mol% or less.

[0062] If the molar fraction of p-phenylenediamine in the diamine component is within the above range, the water absorption of the polyimide resin can be reduced.

[0063] When the diamine component contains 4-aminophenyl-4-aminobenzoate and p-phenylenediamine, the total molar fraction of 4-aminophenyl-4-aminobenzoate and p-phenylenediamine in the diamine component is, for example, 50 mol% to 100 mol%, preferably 70 mol% to 100 mol%, more preferably 80 mol% to 100 mol%, even more preferably 90 mol% to 100 mol%, and particularly preferably 95 mol% to 100 mol%.

[0064] When the diamine component contains 4-aminophenyl-4-aminobenzoate and p-phenylenediamine, the total molar fraction of 4-aminophenyl-4-aminobenzoate and p-phenylenediamine in the diamine component is, for example, 50 mol% or more, preferably 70 mol% or more, more preferably 80 mol% or more, even more preferably 90 mol% or more, particularly preferably 95 mol% or more, and most preferably 100 mol%.

[0065] When the total molar fraction of 4-aminophenyl-4-aminobenzoate and p-phenylenediamine in the diamine component is equal to or greater than the lower limit, thermal expansion can be suppressed. In other words, the thermal expansion coefficient can be reduced. Furthermore, thermal expansion upon moisture absorption can be suppressed. In other words, the moisture absorption thermal expansion coefficient can be reduced. In other words, the water absorption of the polyimide resin can be reduced. As a result, printed circuit boards and electronic devices using this polyimide resin have excellent reliability.

[0066] The polyamic acid is obtained by reacting an acid dianhydride component and a diamine component in an organic solvent. Specifically, the polyamic acid is obtained by reacting an acid dianhydride component containing 3,3',4,4'-biphenyltetracarboxylic dianhydride with a diamine component containing 4-aminophenyl-4-aminobenzoate in an organic solvent. Preferably, the polyamic acid is obtained by reacting an acid dianhydride component containing 3,3',4,4'-biphenyltetracarboxylic dianhydride with a diamine component containing 4-aminophenyl-4-aminobenzoate and p-phenylenediamine in an organic solvent. The diamine component does not contain fluorine atoms or oxydianiline.

[0067] That is, the polyamic acid is obtained as a solution. The organic solvent is not particularly limited, and examples thereof include known organic solvents, and preferred examples include the organic solvents described below.

[0068] The reaction temperature of the acid dianhydride component and the diamine component is, for example, 10° C. to 100° C., and the reaction time is, for example, 6 hours to 24 hours. Furthermore, the acid dianhydride component and the diamine component are reacted, for example, under atmospheric pressure.

[0069] The acid dianhydride component and the diamine component are selected from the molar amount of the acid anhydride group (—CO—O—CO—) of the acid dianhydride component and the molar amount of the amino group (—NH ２ ) are mixed in an amount equivalent to the molar amount of the hydroxybenzoate.

[0070] The polyamic acid includes, for example, a first structural unit represented by the following formula (2). Preferably, the polyamic acid includes a first structural unit represented by the following formula (2) and a second structural unit represented by the following formula (3). More specifically, when the acid dianhydride component includes 3,3'-4,4'-biphenyltetracarboxylic dianhydride and the diamine component includes 4-aminophenyl-4-aminobenzoate, the polyamic acid includes a first structural unit represented by the following formula (2). Furthermore, when the acid dianhydride component includes 3,3'-4,4'-biphenyltetracarboxylic dianhydride and the diamine component includes p-phenylenediamine, the polyamic acid includes a second structural unit represented by the following formula (3).

[0071]

[0072]

[0073] The solids concentration of the polyamic acid solution is, for example, 1% by mass to 60% by mass, or preferably 3% by mass to 50% by mass.

[0074] The solids concentration of the polyamic acid solution is, for example, 1 mass % or more, preferably 3 mass % or more, and for example, 60 mass % or less, preferably 50 mass % or less.

[0075] 2. Polyimide Precursor Composition The polyimide precursor composition contains the above-described polyamic acid, a photosensitizer, and a development accelerator. The polyimide precursor composition can be patterned by photolithography and becomes a polyimide resin by heating.

[0076] <Polyamic Acid> As described above, polyamic acid is a polyimide precursor. In addition, polyamic acid forms a polyimide resin by reacting adjacent amide groups and carboxyl groups in a repeating unit (imidization reaction) to form an imide group-containing closed ring structure. The imidization reaction proceeds, for example, by heating.

[0077] The content of the polyamic acid (solid content) in the polyimide precursor composition (solid content) is, for example, 50% by mass to 99% by mass, preferably 70% by mass to 98% by mass, more preferably 80% by mass to 97% by mass, and even more preferably 90% by mass to 96% by mass.

[0078] The content of polyamic acid (solid content) in the polyimide precursor composition (solid content) is, for example, 50 mass% or more, preferably 70 mass% or more, more preferably 80 mass% or more, even more preferably 90 mass% or more, and for example, 99 mass% or less, preferably 98 mass% or less, more preferably 97 mass% or less, even more preferably 96 mass% or less.

[0079] When the content of the polyamic acid (solid content) in the polyimide precursor composition (solid content) is within the above range, the polyimide precursor composition has a good viscosity.

[0080] <Photosensitizer> The photosensitizer is a component that promotes imidization of polyamic acid in the portion irradiated with light (exposed portion) in the exposure step of the photolithography method (the portion where imidization of polyamic acid is promoted becomes less soluble in the developer used in the development step that follows the exposure step). Therefore, it is possible to improve adhesion to the metal that is the material of the wiring layer.

[0081] Examples of the photosensitizer include pyridine-based photosensitizers.

[0082] Examples of pyridine-based photosensitizers include compounds (1,4-dihydropyridine derivatives) represented by the following general formula (4): In general formula (4), R1, R2, R3, R4, and R5 each represent a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and may be the same as or different from one another. Also, in general formula (4), Ar represents an aryl group having a nitro group at the ortho position.

[0083]

[0084] In general formula (4), R1 is, for example, a hydrogen atom or a methyl group. R2 is, for example, a hydrogen atom or a methyl group. R3 is, for example, a methyl group or an ethyl group. R4 is, for example, a methyl group or an ethyl group. R5 is, for example, a methyl group or an ethyl group. Ar is, for example, a 2-nitrophenyl group.

[0085] Examples of pyridine-based photosensitizers represented by general formula (4) include 1-ethyl-3,5-dimethoxycarbonyl-4-(2-nitrophenyl)-4-hydropyridine, 1-methyl-3,5-dimethoxycarbonyl-4-(2-nitrophenyl)-4-hydropyridine, 1-propyl-3,5-dimethoxycarbonyl-4-(2-nitrophenyl)-4-hydropyridine, and 1-propyl-3,5-diethoxycarbonyl-4-(2-nitrophenyl)-4-hydropyridine.

[0086] A preferred example of the pyridine-based photosensitizer is 1-ethyl-3,5-dimethoxycarbonyl-4-(2-nitrophenyl)-4-hydropyridine represented by the following formula (5).

[0087]

[0088] Pyridine-based photosensitizers (1,4-dihydropyridine derivatives) can be obtained, for example, by reacting a substituted benzaldehyde with a twice-fold molar amount of alkylpropiolate (propargylic acid alkyl ester) and a specific primary amine in glacial acetic acid under reflux (Khim. Geterotsikl. Soed., pp. 1067-1071, 1982).

[0089] The content of the photosensitizer in the polyimide precursor composition (solid content) is, for example, 0.1 mass % to 15.0 mass %, preferably 0.5 mass % to 10.0 mass %, more preferably 0.8 mass % to 5.0 mass %, still more preferably 1.0 mass % to 3.0 mass %, and particularly preferably 1.2 mass % to 2.0 mass %.

[0090] The content of the photosensitizer in the polyimide precursor composition (solid content) is, for example, 0.1 mass% or more, preferably 0.5 mass% or more, more preferably 0.8 mass% or more, even more preferably 1.0 mass% or more, and particularly preferably 1.2 mass% or more, and for example, 15.0 mass% or less, preferably 10.0 mass% or less, more preferably 5.0 mass% or less, even more preferably 3.0 mass% or less, and particularly preferably 2.0 mass% or less.

[0091] When the content of the photosensitizer in the polyimide precursor composition (solid content) is equal to or greater than the above-mentioned lower limit, the solubility of the exposed portion in a developer can be sufficiently reduced, and the adhesion to the metal that is the material of the wiring layer can be improved.

[0092] When the content of the photosensitizer in the polyimide precursor composition (solid content) is equal to or less than the above upper limit, precipitation of the solid content during storage of the polyimide precursor composition can be suppressed, and further, a reduction in the thickness of the polyimide resin formed in the heat curing step after the development step of the photolithography method can be suppressed.

[0093] The amount of the photosensitizer blended relative to 100 parts by mass of the polyamic acid (solid content) is, for example, 0.1 parts by mass to 15.0 parts by mass, preferably 0.5 parts by mass to 10.0 parts by mass, more preferably 0.8 parts by mass to 5.0 parts by mass, even more preferably 1.0 parts by mass to 3.0 parts by mass, and particularly preferably 1.2 parts by mass to 2.0 parts by mass.

[0094] The amount of the photosensitizer blended relative to 100 parts by mass of polyamic acid (solid content) is, for example, 0.1 parts by mass or more, preferably 0.5 parts by mass or more, more preferably 0.8 parts by mass or more, even more preferably 1.0 parts by mass or more, particularly preferably 1.2 parts by mass or more, and for example, 15.0 parts by mass or less, preferably 10.0 parts by mass or less, more preferably 5.0 parts by mass or less, even more preferably 3.0 parts by mass or less, particularly preferably 2.0 parts by mass or less.

[0095] <Development Accelerator> The development accelerator accelerates the dissolution of the portion that has not been irradiated with light in the exposure step of the photolithography method (unexposed portion) in the developer in the development step.

[0096] The development accelerator may be, for example, an ester compound. Since the development accelerator has an ester bond, when a basic developer is used in the development step, the ester bond of the development accelerator is hydrolyzed by the basic developer to generate an alcohol and a carboxylic acid, thereby increasing the hydrophilicity and allowing the basic developer to more easily penetrate into the polyamic acid.

[0097] In this way, the use of an ester compound improves the permeability of the basic developer into the polyamic acid, thereby enabling the unexposed areas to be removed more reliably in the development step, and therefore the formed polyimide resin has excellent patterning precision.

[0098] The development accelerators may be used alone or in combination of two or more.

[0099] Examples of the ester compound include nitrogen-free ester compounds and nitrogen-containing ester compounds. From the viewpoint of heat resistance, nitrogen-free ester compounds are preferred.

[0100] Examples of the nitrogen-free ester compound include nitrogen-free ester compounds that do not contain an aromatic ring, and nitrogen-free ester compounds that contain an aromatic ring, and preferably nitrogen-free ester compounds that contain an aromatic ring.

[0101] Examples of the nitrogen-free ester compound that does not contain an aromatic ring include cyclic ester compounds.

[0102] Examples of cyclic ester compounds include ε-caprolactone, glycolide, DL-lactide, tetramethylglycolide, delta-octanolactone, DL-mevalonolactone, and gamma-heptanolactone.

[0103] Examples of the aromatic ring-containing nitrogen-free ester compound include aromatic ring-containing aliphatic carboxylic acid ester compounds and aromatic carboxylic acid ester compounds. From the viewpoint of heat resistance, aromatic carboxylic acid ester compounds are preferred.

[0104] Examples of aromatic ring-containing aliphatic carboxylic acid ester compounds include aromatic ring-containing acetate ester compounds.

[0105] Examples of aromatic ring-containing acetate ester compounds include (3-methylphenyl)acetate, methyl-2-hydroxy-2-phenylacetate, methyl-2-(4-hydroxyphenyl)acetate, ethyl-2-(2-methylphenyl)acetate, ethyl-2-(4-hydroxy-3-methoxyphenyl)acetate, and ethyl-2-hydroxy-2-(3-hydroxy-4-methoxyphenyl)acetate.

[0106] Examples of aromatic carboxylic acid ester compounds include benzoic acid ester compounds, phthalic acid ester compounds, and trimellitic acid ester compounds. Benzoic acid ester compounds are preferred.

[0107] Examples of the benzoic acid ester compound include ethyl 3-hydroxybenzoate, ethyl 2-acetyloxybenzoate, ethyl 2-ethoxy-6-hydroxybenzoate, ethyl 3,5-dihydroxybenzoate, ethyl 2,4-dihydroxy-6-methylbenzoate, 2-hydroxyethyl-2-hydroxybenzoate, and phenyl benzoate (phenyl benzoate), and preferably phenyl benzoate (phenyl benzoate).

[0108] Benzoic acid ester compounds also include 4-hydroxybenzoic acid (parabens) represented by the following general formula (6):

[0109]

[0110] In general formula (6), R6 is a hydrocarbon group having 4 or more carbon atoms.

[0111] Examples of 4-hydroxybenzoic acids (parabens) include butyl-4-hydroxybenzoate (butylparaben) shown in the following formula (7): isobutyl-4-hydroxybenzoate (isobutylparaben), hexyl-4-hydroxybenzoate (hexylparaben), 2-methylpropyl-4-hydroxybenzoate, 2-ethylhexyl-4-hydroxybenzoate, and benzyl-4-hydroxybenzoate (benzylparaben).

[0112]

[0113] Examples of phthalate compounds include dimethyl phthalate, diethyl phthalate, dipropyl phthalate, diisopropyl phthalate, dibutyl phthalate, diisobutyl phthalate, dihexyl phthalate, diphenyl phthalate, and bis(2-methoxyethyl) phthalate.

[0114] The trimellitic acid ester compounds include trimethyl trimellitate, tripropyl trimellitate, tributyl trimellitate, and tris(2-ethylhexyl) trimellitate.

[0115] The nitrogen-free ester compound is preferably a benzoate compound, more preferably a 4-hydroxybenzoic acid (paraben), and even more preferably butyl-4-hydroxybenzoate (butylparaben).

[0116] Examples of the nitrogen-containing ester compound include imide acrylate compounds.

[0117] Examples of imide acrylate compounds include N-acryloyloxyethylhexahydrophthalimide, N-acryloyloxyethyl-1,2,3,6-tetrahydrophthalimide, and N-acryloyloxyethyl-3,4,5,6-tetrahydrophthalimide.

[0118] Examples of the development accelerator include 4-hydroxybenzoic acids and imide acrylate compounds, and preferably 4-hydroxybenzoic acids. Specifically, a preferred example of the development accelerator is butyl-4-hydroxybenzoate (butylparaben).

[0119] The content of the development accelerator in the polyimide precursor composition (solid content) is, for example, 0.1% by mass to 20.0% by mass, preferably 0.5% by mass to 15.0% by mass, more preferably 1.0% by mass to 10.0% by mass, still more preferably 1.5% by mass to 7.0% by mass, and particularly preferably 2.0% by mass to 5.0% by mass.

[0120] The content of the development accelerator in the polyimide precursor composition (solid content) is, for example, 0.1% by mass or more, preferably 0.5% by mass or more, more preferably 1.0% by mass or more, even more preferably 1.5% by mass or more, and particularly preferably 2.0% by mass or more, and for example, 20.0% by mass or less, preferably 15.0% by mass or less, more preferably 10.0% by mass or less, even more preferably 7.0% by mass or less, and particularly preferably 5.0% by mass or less.

[0121] The amount of the development accelerator blended relative to 100 parts by mass of the polyamic acid (solid content) is, for example, 0.1 to 20.0 parts by mass, preferably 0.5 to 15.0 parts by mass, more preferably 1.0 to 10.0 parts by mass, even more preferably 1.5 to 7.0 parts by mass, and particularly preferably 2.0 to 5.0 parts by mass.

[0122] The amount of the development accelerator blended relative to 100 parts by mass of the polyamic acid (solid content) is, for example, 0.1 parts by mass or more, preferably 0.5 parts by mass or more, more preferably 1.0 parts by mass or more, even more preferably 1.5 parts by mass or more, particularly preferably 2.0 parts by mass or more, and for example, 20.0 parts by mass or less, preferably 15.0 parts by mass or less, more preferably 10.0 parts by mass or less, even more preferably 7.0 parts by mass or less, particularly preferably 5.0 parts by mass or less.

[0123] When the blending amount of the development accelerator per 100 parts by mass of the polyamic acid (solid content) is equal to or greater than the above lower limit, excessive imidization of the polyamic acid can be suppressed. On the other hand, when the blending amount of the development accelerator per 100 parts by mass of the polyamic acid (solid content) is equal to or less than the above upper limit, compatibility is excellent and development contrast can be improved.

[0124] The polyimide precursor composition may contain other components, such as an amine compound and a photosensitizer.

[0125] The amine compound improves the adhesion between the metal that is the material of the wiring layer and the polyimide resin.

[0126] Examples of amine compounds include aliphatic amine compounds, aromatic amine compounds, and nitrogen-containing heterocyclic compounds. Examples of aliphatic amines include methylamine, ethylamine, propylamine, dimethylamine, diethylamine, N,N-dimethylethylenediamine, N,N-dimethylformamide dimethyl acetal, trimethylamine, and triethylamine. Examples of aromatic amines include aniline, benzylamine, N-methylaniline, N-ethylaniline, N,N-dimethylaniline, 3-aminobenzoic acid, and 4-aminobenzoic acid. Examples of nitrogen-containing heterocyclic compounds include pyridine compounds, morpholine compounds, imidazole compounds, and triazole compounds.

[0127] The amine compounds may be used alone or in combination of two or more.

[0128] The amount of the amine compound to be blended is 0.01 to 10 parts by mass relative to 100 parts by mass of the polyamic acid (solid content).

[0129] Examples of photosensitizers include 3,3'-carbonylbis(7-N,N-dimethoxy)coumarin, 3-benzoylcoumarin, 3-benzoyl-7-N,N-methoxycoumarin, and benzalacetophenone.

[0130] The amount of the photosensitizer blended relative to 100 parts by mass of the polyamic acid (solid content) is, for example, 0.05 to 20 parts by mass.

[0131] The polyimide precursor composition can be prepared, for example, by mixing the above-described polyamic acid, a photosensitizer, a development accelerator, and other components added as needed. The polyimide precursor composition can be prepared, for example, by mixing a solution of the above-described polyamic acid, a photosensitizer, a development accelerator, and other components added as needed. Alternatively, the polyimide precursor composition can be prepared, for example, by mixing the above-described polyamic acid, a photosensitizer, a development accelerator, and other components added as needed in an organic solvent, to form a diluted solution (varnish) of the polyimide precursor composition.

[0132] The organic solvent may be, for example, an aprotic polar solvent.

[0133] Aprotic polar solvents include, for example, N-methyl-2-pyrrolidone, dimethylacetamide, dimethylsulfoxide, dimethylformamide, and hexamethylphosphoramide.

[0134] The amount of the organic solvent to be blended relative to 100 parts by mass of the polyamic acid (solid content) is, for example, 150 to 2000 parts by mass.

[0135] The content of the polyamic acid (solid content) in the diluted solution (varnish) of the polyimide precursor composition is, for example, 5% by mass to 30% by mass, preferably 8% by mass to 25% by mass, and more preferably 10% by mass to 20% by mass.

[0136] The content of polyamic acid (solid content) in the diluted solution (varnish) of the polyimide precursor composition is, for example, 5 mass% or more, preferably 8 mass% or more, more preferably 10 mass% or more, and for example, 30 mass% or less, preferably 25 mass% or less, more preferably 20 mass% or less.

[0137] When the content of polyamic acid (solid content) in the diluted solution (varnish) of the polyimide precursor composition is within the above range, a good viscosity of the polyimide precursor composition can be ensured.

[0138] The content of the photosensitizer (solid content) in the diluted solution (varnish) of the polyimide precursor composition is, for example, 0.05% by mass to 10% by mass, preferably 0.08% by mass to 5.0% by mass, more preferably 0.10% by mass to 3.0% by mass, even more preferably 0.12% by mass to 1.0% by mass, and particularly preferably 0.15% by mass to 0.50% by mass.

[0139] The content of the photosensitizer (solid content) in the diluted solution (varnish) of the polyimide precursor composition is, for example, 0.05 mass% or more, preferably 0.08 mass% or more, more preferably 0.10 mass% or more, even more preferably 0.12 mass% or more, and particularly preferably 0.15 mass% or more, and for example, 10 mass% or less, preferably 5.0 mass% or less, more preferably 3.0 mass% or less, even more preferably 1.0 mass% or less, and particularly preferably 0.50 mass% or less.

[0140] When the content of the photosensitizer (solid content) in the diluted solution (varnish) of the polyimide precursor composition is equal to or greater than the lower limit, the imidization of the polyamic acid by heating in the exposed area of ​​the polyimide precursor composition is promoted, the solubility of the exposed area in a developer is reduced, and a polyimide resin with excellent electrical properties can be formed. When the content of the photosensitizer (solid content) in the diluted solution (varnish) of the polyimide precursor composition is equal to or less than the upper limit, a decrease in the thickness of the polyimide resin pattern can be suppressed during the heating step.

[0141] The content of the development accelerator (solid content) in the diluted solution (varnish) of the polyimide precursor composition is, for example, 0.10 mass % to 10 mass %, preferably 0.20 mass % to 5.0 mass %, more preferably 0.30 mass % to 3.0 mass %, still more preferably 0.40 mass % to 1.0 mass %, and particularly preferably 0.45 mass % to 0.80 mass %.

[0142] The content of the development accelerator (solid content) in the diluted solution (varnish) of the polyimide precursor composition is, for example, 0.10 mass % or more, preferably 0.20 mass % or more, more preferably 0.30 mass % or more, even more preferably 0.40 mass % or more, and particularly preferably 0.45 mass % or more, and for example, 10 mass % or less, preferably 5.0 mass % or less, more preferably 3.0 mass % or less, even more preferably 1.0 mass % or less, and particularly preferably 0.80 mass % or less.

[0143] When the content of the development accelerator (solid content) in the diluted solution (varnish) of the polyimide precursor composition is equal to or higher than the lower limit, excessive imidization of the polyamic acid can be suppressed. When the content of the development accelerator (solid content) in the diluted solution (varnish) of the polyimide precursor composition is equal to or lower than the upper limit, sufficient compatibility can be ensured, and development contrast can be improved.

[0144] The polyimide precursor composition (or varnish) forms a polyimide resin by heat curing.

[0145] 3. Polyimide Resin The polyimide resin is formed from the polyimide precursor composition. The polyimide resin is used, for example, as a coating layer for a printed circuit board.

[0146] The coefficient of hygroscopic thermal expansion (CHE) of the polyimide resin is, for example, 15.0 or less, preferably 13.0 or less, more preferably 12.0 or less, still more preferably 11.0 or less, and particularly preferably 10.5 or less.

[0147] If the coefficient of hygroscopic thermal expansion (CHE) of the polyimide resin is equal to or less than the upper limit, the polyimide resin has low hygroscopicity.

[0148] The coefficient of hygroscopic thermal expansion (CHE) of the polyimide resin can be determined by the method described in the examples below.

[0149] The coefficient of thermal expansion (CTE) of the polyimide resin (average coefficient of thermal expansion from 100°C to 250°C) is, for example, 22.0 or less, preferably 21.0 or less, more preferably 20.0 or less, even more preferably 19.0 or less, and particularly preferably 18.0 or less.

[0150] If the coefficient of thermal expansion (CTE) of the polyimide resin (average coefficient of thermal expansion from 100° C. to 250° C.) is equal to or less than the upper limit, the polyimide resin can suppress thermal expansion.

[0151] The coefficient of thermal expansion (CTE) of the polyimide resin (average coefficient of thermal expansion from 100° C. to 250° C.) can be determined by the method described in the examples below.

[0152] The initial dielectric constant of the polyimide resin at 10 GHz is, for example, 5.0 or less, preferably 4.0 or less, more preferably 3.8 or less, and still more preferably 3.6 or less.

[0153] If the initial dielectric constant of the polyimide resin at 10 GHz is equal to or less than the upper limit, the polyimide resin has an excellent dielectric constant.

[0154] The initial dielectric constant of the polyimide resin at 10 GHz can be determined by the Split Post Dielectric Resonator (SPDR) method using a PNA network analyzer (manufactured by Agilent Technologies).

[0155] The dielectric constant of the polyimide resin at 10 GHz after 24 hours of immersion is, for example, 5.0 or less, preferably 4.0 or less, more preferably 3.8 or less, still more preferably 3.6 or less, and particularly preferably 3.5 or less.

[0156] If the dielectric constant of the polyimide resin after 24 hours of immersion at 10 GHz is equal to or less than the upper limit, the polyimide resin has low moisture absorption, and an increase in the dielectric constant due to moisture absorption can be suppressed.

[0157] The dielectric constant of a polyimide resin after 24 hours of immersion is measured after immersing the polyimide resin in pure water at 25° C. for 24 hours, removing it from the pure water, wiping off any water droplets on the surface, and then measuring the dielectric constant at 10 GHz after 24 hours of immersion.

[0158] The initial dielectric loss tangent (tan δ) of the polyimide resin at 10 GHz is, for example, 0.015 or less, preferably 0.012 or less, more preferably 0.010 or less, and still more preferably 0.009 or less.

[0159] If the initial dielectric loss tangent (tan δ) of the polyimide resin at 10 GHz is equal to or less than the upper limit, the polyimide resin has a small dielectric loss tangent (dielectric loss).

[0160] The initial dielectric loss tangent (tan δ) of the polyimide resin at 10 GHz can be determined by the method described in the examples below.

[0161] The dielectric loss tangent (tan δ) of the polyimide resin after 24 hours of immersion at 10 GHz is, for example, 0.015 or less, preferably 0.013 or less, more preferably 0.012 or less, and still more preferably 0.010 or less.

[0162] If the dielectric loss tangent (tan δ) of the polyimide resin after 24 hours of immersion at 10 GHz is equal to or less than the upper limit value, the polyimide resin has low moisture absorption, and an increase in the dielectric loss tangent (dielectric loss) due to moisture absorption can be suppressed.

[0163] The dielectric loss tangent (tan δ) of the polyimide resin after immersion for 24 hours can be determined by the method described in the examples below.

[0164] At 10 GHz, the difference between the dielectric dissipation factor (tan δ) of the polyimide resin after 24 hours of immersion and the initial dielectric dissipation factor (tan δ) of the polyimide resin (dielectric dissipation factor (tan δ) of the polyimide resin after 24 hours of immersion - initial dielectric dissipation factor (tan δ) of the polyimide resin) is, for example, 0.006 or less, preferably 0.005 or less, more preferably 0.004 or less, even more preferably 0.003 or less, and particularly preferably 0.001 or less.

[0165] If the difference between the dielectric loss tangent (tan δ) of a polyimide resin after 24 hours of immersion at 10 GHz and the initial dielectric loss tangent (tan δ) of the polyimide resin is equal to or less than the upper limit, the polyimide resin has low moisture absorption and can suppress an increase in the dielectric loss tangent (dielectric loss) due to moisture absorption. As a result, printed circuit boards and electronic devices using this polyimide resin have excellent reliability.

[0166] 4. Wired Circuit Board The wired circuit board includes, for example, a base material, an insulating layer, a wiring layer, and a coating layer in this order in the thickness direction. The coating layer is disposed so as to cover the wiring layer. The coating layer contains a polyimide resin formed from the polyimide precursor composition described above.

[0167] The shape of the substrate may be, for example, a film (including a sheet) having a predetermined thickness, or a plate.

[0168] Examples of materials for the substrate include metals. Preferred examples include aluminum, stainless steel, and copper. More preferred examples include stainless steel.

[0169] The thickness of the substrate is, for example, 5 μm to 300 μm, preferably 10 μm to 200 μm, and more preferably 20 μm to 150 μm.

[0170] The material of the insulating layer is not particularly limited, and known materials can be used. A preferred example of the material of the insulating layer is a polyimide resin. Alternatively, a polyimide resin formed from the polyimide precursor composition described above may be used.

[0171] The thickness of the insulating layer is, for example, 1 μm to 50 μm, or preferably 5 μm to 30 μm.

[0172] Examples of materials for the wiring layer include metals, preferably chromium and copper, and more preferably copper.

[0173] The material for the wiring layer may be used alone or in combination of two or more kinds, preferably a combination of chromium and copper.

[0174] The thickness of the wiring layer is, for example, 1 μm to 100 μm, preferably 5 μm to 50 μm, and more preferably 10 μm to 30 μm.

[0175] Next, a method for forming a coating layer of polyimide resin from the above polyimide precursor composition on the wired circuit board 1 will be described with reference to FIGS. 1A to 1E.

[0176] 1A, an insulating layer material (e.g., a polyimide precursor composition) is applied to a substrate S and cured to form an insulating layer 10. A metal wiring layer material is then deposited as a base by sputtering to form a metal layer 21. A plating resist 30 having a reverse pattern to a predetermined wiring pattern is then formed using a dry film resist, and a conductor pattern 20 (wiring layer) that forms the predetermined wiring pattern is then formed by copper plating 22 in the portions of the metal layer 21 where the plating resist is not formed, using a semi-additive method (lamination process).

[0177] Thereafter, as shown in FIG. 1B, the plating resist 30 is removed by chemical etching, and the metal layer 21 on which the plating resist was formed is also removed by chemical etching (etching step).

[0178] Next, as shown in FIG. 1C, a diluted solution (varnish) of the polyimide precursor composition is applied and then dried by heating to form a coating 40A (application step).

[0179] Examples of the application method include spin coating and screen printing.

[0180] The drying temperature is, for example, 100° C. to 200° C. The drying time is, for example, 1 minute to 15 minutes.

[0181] The thickness of the coating 50A is, for example, 1 μm to 50 μm, or preferably 10 μm to 40 μm.

[0182] The thickness of the coating 50A is, for example, 1 μm or more, or preferably 10 μm or more, and for example, 50 μm or less, or preferably 40 μm or less.

[0183] A metal underlayer may be formed before applying the diluted solution (varnish) of the polyimide precursor composition. Specifically, the metal underlayer may be formed by metal plating after the etching step. Examples of materials for the metal underlayer include nickel and chromium. The thickness of the metal underlayer is, for example, 0.01 μm to 10 μm, preferably 0.05 μm to 5 μm.

[0184] 1D, the coating 40A is irradiated with ultraviolet light through a photomask M (exposure step). The photomask M has openings Ma corresponding to the pattern shape of the conductor pattern 20 (wiring layer).

[0185] The wavelength of the irradiated ultraviolet light is, for example, 300 nm to 450 nm. The cumulative irradiation amount of the ultraviolet light is, for example, 100 mJ / cm. ２ ~1000mJ / cm ２ is.

[0186] The film 40A is irradiated with ultraviolet light through the photomask M, resulting in exposed portions 41 and unexposed portions 42. After the ultraviolet light irradiation, the film 40A may be preheated.

[0187] The preheating temperature is, for example, 100° C. to 300° C. The preheating time is, for example, 1 minute to 30 minutes.

[0188] Next, as shown in FIG. 1E, the coating 40A is developed. Specifically, the unexposed portions 42 of the coating 40A are dissolved and removed by a developer (development step). After development, the exposed portions 41 are heated. As a result, a polyimide resin is formed in the exposed portions 41 of the coating 40A, forming a coating layer 40B.

[0189] The developer may be, for example, a basic developer. Examples of the basic developer include inorganic alkaline solutions and organic alkaline solutions. Examples of the inorganic alkaline solutions include aqueous sodium hydroxide solutions and aqueous potassium hydroxide solutions. Examples of the organic alkaline solutions include aqueous tetramethylammonium hydroxide (TMAH) solutions and TMAH / equinene solutions, with TMAH / equinene solutions being preferred. Equinene is a mixed solvent primarily composed of ethanol.

[0190] Examples of the developing method include a dipping method, a spray method, and a puddle method.

[0191] The heating temperature is, for example, 300° C. to 450° C. The heating time is, for example, 1 hour to 10 hours.

[0192] In this manner, a laminate is formed on the substrate S, which is made of the insulating layer 10, the conductor pattern 20 (wiring layer) having a predetermined pattern shape, and the coating layer 40B made of polyimide resin and coating the conductor pattern 20 (wiring layer). This results in the wired circuit board 1.

[0193] 5. Electronic Device The electronic device of the present invention includes the above-described wired circuit board.

[0194] Examples of electronic devices include laptop computers and smartphones.

[0195] (Effects) The polyamic acid of the present invention is a reaction product of an acid dianhydride component and a diamine component, wherein the acid dianhydride component contains biphenyltetracarboxylic dianhydride, and the diamine component does not contain fluorine atoms or oxydianiline but contains 4-aminophenyl-4-aminobenzoate. Therefore, the polyamic acid has low water absorption and reduces the environmental load.

[0196] Specifically, in the polyimide precursor composition of the present invention, the diamine component does not contain fluorine atoms. Therefore, the environmental impact can be reduced. Furthermore, the diamine component does not contain oxydianiline, but contains 4-aminophenyl-4-aminobenzoate. Therefore, water absorption can be reduced even without containing fluorine atoms. As a result, a polyimide resin can be formed that has low water absorption and can reduce the environmental impact.

[0197] Therefore, the polyimide resin formed from the polyimide precursor composition of the present invention has low water absorption and can reduce the environmental load, making it possible to produce highly reliable wiring circuit boards and electronic devices that can reduce the environmental load.

[0198] The present invention will be described in more detail below with reference to examples, comparative examples, and reference examples. It should be noted that the present invention is not limited to the examples, comparative examples, and reference examples. The specific numerical values ​​of the blending ratios (contents), physical properties, parameters, etc. used in the following description can be replaced with the upper limit (a numerical value defined as "equal to or less than") or lower limit (a numerical value defined as "equal to or more than" or "exceeding") of the corresponding blending ratios (contents), physical properties, parameters, etc. described in the above-mentioned "Modes for Carrying Out the Invention."

[0199] <Details of Components> The trade names and abbreviations of the components used in each example and each comparative example are described in detail below.

[0200] BPDA: 3,3',4,4'-biphenyltetracarboxylic dianhydride PDA: p-phenylenediamine APAB: 4-aminophenyl-4-aminobenzoate TFMB: 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl ODA: 4,4'-oxydianiline NMP: N-methyl-2-pyrrolidone NKS-4: 1-ethyl-3,5-dimethoxycarbonyl-4-(2-nitrophenyl)-4-hydropyridine n-BP: butyl-4-hydroxybenzoate Aronix: n-acryloyloxyethylhexahydrophthalimide (manufactured by Toagosei Co., Ltd.)

[0201] Synthesis of Polyamic Acid Preparation Example 1 In a 300 mL four-neck flask, a solution containing 32.37 g (110 mmol) of BPDA, 10.71 g (99 mmol) of PDA, 2.51 g (11 mmol) of APAB, and 253 g of NMP was stirred while being heated to 60° C. This resulted in an NMP solution containing the polyamic acid of Preparation Example 1. The synthesized polyamic acid contained the first structural unit and the second structural unit described above. Furthermore, the proportion of the first structural unit in this polyamic acid was 5 mol %, and the proportion of the second structural unit was 95 mol %.

[0202] Preparation Examples 2 to 5, Comparative Preparation Examples 1 and 2 Polyamic acids of each Example and Comparative Example were prepared in the same manner as the polyamic acid of Preparation Example 1, except that the type and blending ratio of the diamine component were changed to obtain the composition ratios shown in Table 1. Note that Comparative Preparation Example 1 does not contain APAB but does contain TFMB. Furthermore, Comparative Preparation Example 2 does not contain APAB but does contain ODA.

[0203] Example 1 <Preparation of Polyimide Precursor Composition> Next, NKS-4 (photosensitizer) and n-BP (development accelerator) were mixed with the NMP solution containing the polyamic acid of Preparation Example 1 above to prepare a varnish of a photosensitive polyimide precursor composition. The polyimide precursor composition was prepared by mixing the polyamic acid (solid content), NKS-4 (photosensitizer), and n-BP (development accelerator) in a compositional ratio (mass ratio) of 95.4:1.5:3.1. This resulted in the preparation of an NMP solution (varnish) of the polyimide precursor composition of Example 1.

[0204] <Preparation of Polyimide Resin Film> The solution (varnish) of the polyimide precursor composition described above was spin-coated onto a SUS foil (thickness: 20 μm) as a substrate using a spin coater (trade name: Opticoat MS-B200, manufactured by Mikasa Co., Ltd.) at 1100 rpm for 30 seconds, and the resulting film was dried by heating at 130°C for 5 minutes in an explosion-proof dryer (trade name: SPHH-201, manufactured by Espec Corporation) to form a film (thickness: 28 μm) made of the polyimide precursor composition of Example 1. Next, this film was irradiated with ultraviolet light (wavelength: 365 nm, 400 mJ / cm) using a simple exposure device (trade name: UV-2001M-ND, manufactured by CES Co., Ltd.). ２ ) and heated at 185°C for 5 minutes using a blower dryer (trade name: DRM320DA, manufactured by Advantec Co., Ltd.). Furthermore, using a laboratory curing oven (trade name: Infrared Heating System E42327, manufactured by Noritake Co., Ltd.), the mixture was heated at a target temperature of 360°C and cured (imidized), thereby producing a polyimide resin film having a thickness of 20 μm on the substrate. The substrate was then removed to obtain the polyimide resin of Example 1.

[0205] Examples 2 to 4 Polyimide precursor compositions of each Example were prepared in the same manner as in Example 1, except that the polyamic acids shown in Table 2 were used, and film-like polyimide resins (thickness: 20 μm) were produced.

[0206] Comparative Examples 1 to 3 Polyimide precursor compositions of each Comparative Example were prepared in the same manner as the polyimide precursor composition of Example 1, except that the polyamic acids and development accelerators shown in Table 2 were used and the compositional ratios of the components in the polyimide precursor compositions were changed, and film-like polyimide resins (thickness: 20 μm) were produced.

[0207] Reference Examples 1 to 4 The polyamic acids shown in Table 3 were used as the polyimide precursor compositions of each Reference Example without blending a photosensitizer or a development accelerator, to prepare polyimide resin films (thickness: 20 μm).

[0208] <Evaluation> [Environmental Load] The environmental load of the polyimide resins of each Example, Comparative Example, and Reference Example was evaluated according to the following criteria. The results are shown in Tables 2 and 3.

[0209] {Criteria} A: Polyimide resin does not contain fluorine atoms B: Polyimide resin contains fluorine atoms

[0210] [Coefficient of Hygroscopic Thermal Expansion (CHE)] The polyimide resins (thickness: 20 μm) of each Example, Comparative Example, and Reference Example were cut into a size of 5 mm wide and 1.5 mm long to prepare samples for measuring the coefficient of hygroscopic thermal expansion (CHE). Each sample was attached to the chuck of a humidity-controlled TMA (product name: HC-TMA400SA, manufactured by Bruker). The samples were humidified from 5% RH to 75% RH using a tensile method in which a 20 g load was applied at a constant temperature of 30°C. The coefficient of hygroscopic thermal expansion (CHE) of each polyimide resin was determined by measuring the elongation 5 hours after reaching 75% RH as the maximum elongation point. The coefficient of hygroscopic thermal expansion (CHE) was evaluated according to the following criteria. The results are shown in Tables 2 and 3. Note that for Reference Examples 1 to 4, only numerical values ​​are shown and the samples were not evaluated according to the following criteria.

[0211] {Standards} A: 10 or less B: Over 10, 12 or less C: Over 12

[0212] [Coefficient of Thermal Expansion (CTE)] The polyimide resin (thickness: 20 μm) of each Example, Comparative Example, and Reference Example was cut into a size of 5 mm wide and 1.5 mm long to prepare a sample for measuring the coefficient of thermal expansion (CTE). Each sample was placed in a thermomechanical analyzer (trade name: TMA7100, manufactured by Hitachi High-Tech Corporation), and the temperature was increased from 25°C to 250°C at a heating rate of 5°C / min while applying a load of 50 mN. The average coefficient of thermal expansion from 100°C to 250°C was determined as the coefficient of thermal expansion (CTE). The coefficient of thermal expansion (CTE) was evaluated according to the following criteria. The results are shown in Tables 2 and 3. Note that for Reference Examples 1 to 4, only numerical values ​​are shown and the samples were not evaluated according to the following criteria.

[0213] {Standards} A: 18 or less B: Over 18, 20 or less C: Over 20

[0214] [Difference in Dielectric Loss Tangent (tan δ)] The initial dielectric loss tangent (tan δ) at 10 GHz was determined for each polyimide resin (thickness: 20 μm) of each Example, Comparative Example, and Reference Example using a PNA network analyzer (manufactured by Agilent Technologies) by the Split Post Dielectric Resonator (SPDR) method.

[0215] Next, the polyimide resins of each Example, Comparative Example, and Reference Example were immersed in pure water for 24 hours at 25° C. Thereafter, each polyimide resin was removed from the pure water, water droplets on the surface were wiped off, and the dielectric loss tangent (tan δ) at 10 GHz after 24 hours of immersion was immediately determined using a PNA network analyzer (manufactured by Agilent Technologies).

[0216] Then, the difference between the initial dielectric loss tangent (tan δ) and the dielectric loss tangent (tan δ) after 24 hours of immersion (dielectric loss tangent (tan δ) after 24 hours of immersion - initial dielectric loss tangent (tan δ)) was calculated and evaluated according to the following criteria. The results are shown in Tables 2 and 3. Note that for Reference Examples 1 to 4, only numerical values ​​are shown and evaluation according to the following criteria was not performed.

[0217] {Standard} A: 0.001 or less B: Exceeding 0.001, 0.003 or less C: Exceeding 0.003, 0.005 or less D: Exceeding 0.005

[0218]

[0219]

[0220]

[0221] The above invention is provided as an exemplary embodiment of the present invention, but this is merely an example and should not be interpreted as limiting. Modifications of the present invention that are obvious to those skilled in the art are intended to be included in the scope of the following claims.

[0222] The polyimide resin formed from the polyimide precursor composition containing the polyamic acid of the present invention is suitable for use in an insulating layer and / or a coating layer used in a wiring circuit board. The wiring circuit board using the polyimide resin is suitable for use in electronic devices such as notebook personal computers and smartphones.

[0223] REFERENCE SIGNS LIST 1 Wired circuit board S Substrate 10 Insulating layer 20 Conductor pattern (wiring layer) 21 Metal layer 22 Copper plating 30 Plating resist 40A Coating 40B Covering layer 41 Exposed portion 42 Unexposed portion

Claims

1. A reaction product of an acid dianhydride component and a diamine component, wherein the acid dianhydride component includes biphenyltetracarboxylic dianhydride, and the diamine component does not include a fluorine atom and oxydianiline and includes 4-aminophenyl-4-aminobenzoate, a polyamic acid.

2. The polyamic acid according to claim 1, wherein the diamine component further includes p-phenylenediamine, and the total content ratio of the 4-aminophenyl-4-aminobenzoate and the p-phenylenediamine in the diamine component is 90 mol% or more.

3. The polyamic acid according to claim 2, wherein the diamine component consists of the 4-aminophenyl-4-aminobenzoate and the p-phenylenediamine.

4. The polyamic acid according to claim 3, wherein the content ratio of the p-phenylenediamine in the diamine component is 50 mol% or more.

5. A polyimide precursor composition comprising the polyamic acid according to any one of claims 1 to 4, a photosensitizer, and a development accelerator.

6. The polyimide precursor composition according to claim 5, wherein the photosensitizer is a pyridine-based photosensitizer.

7. The polyimide precursor composition according to claim 5, wherein the development accelerator is 4-hydroxybenzoic acids.

8. A polyimide resin formed from the polyimide precursor composition according to claim 5.

9. A wiring circuit board comprising the polyimide resin according to claim 8.

10. An electronic device comprising the wiring circuit board according to claim 9.

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