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

Abstract

To provide a polyamic acid, a polyimide precursor composition, a polyimide resin, a wiring circuit board, and an electronic apparatus, having low water absorption and capable of reducing an environmental load.SOLUTION: A polyamic acid is a reaction product of an acid dianhydride component and a diamine component. The acid dianhydride component includes a biphenyltetracarboxylic acid dianhydride. The diamine component does not include a fluorine atom nor oxydianiline, but includes 4-aminophenyl-4-amino benzoate.SELECTED DRAWING: None

Description

Technical Field

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

Background Art

[0002] Conventionally, as a wiring circuit board used in an electronic device, a laminate in which a metal base material, an insulating layer, a wiring layer, and a coating layer are laminated is known.

[0003] The insulating layer and the coating layer used for such a wiring circuit board are made of, for example, a polyimide resin, and the polyimide resin is formed from a polyamic acid as a material (see, for example, Patent Document 1 below). Since the polyamic acid described in Patent Document 1 contains a fluorine atom, a polyimide resin having low water absorption can be formed, and a wiring circuit board using such a polyimide resin is excellent in reliability.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] On the other hand, in recent years, a polyimide resin containing no fluorine atom has been demanded for the purpose of reducing the environmental load.

[0006] That is, a polyimide resin having low water absorption and capable of further reducing the environmental load is required, and thus a polyamic acid for forming such a polyimide resin is required.

[0007] An object of the present invention is to provide a polyamic acid, a polyimide precursor composition, a polyimide resin, a wiring circuit board, and an electronic device, which have low water absorption and can further reduce the environmental load.

Means for Solving the Problem

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

[0009] The present invention [2] is such that the diamine component further contains 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, and contains the polyamic acid according to [1].

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

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

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

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

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

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

[0016] The present invention [9] contains a wiring circuit board including the polyimide resin according to [8].

[0017] The present invention

[10] contains an electronic device including the wiring circuit board according to [9].

Advantages of the Invention

[0018] The polyamic acid of the present invention is a reaction product of an acid dianhydride component and a diamine component. The acid dianhydride component contains biphenyltetracarboxylic dianhydride, and the diamine component does not contain a fluorine atom and oxydianiline, and contains 4-aminophenyl-4-aminobenzoate. Therefore, a polyimide resin having low water absorption and capable of further reducing the environmental load can be formed.

[0019] The polyimide precursor composition of the present invention contains the polyamic acid of the present invention. Therefore, a polyimide resin having low water absorption and capable of further reducing the environmental load can be formed.

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

[0021] The wiring circuit board of the present invention contains the polyimide resin of the present invention. Therefore, it reduces the environmental load and is further excellent in reliability.

[0022] The electronic device of the present invention contains the wiring circuit board of the present invention. Therefore, it reduces the environmental load and is further excellent in reliability.

Brief Description of the Drawings

[0023]

Figure 1

Mode for Carrying Out the Invention

[0024] 1. Polyamic acid The polyamic acid of the present invention is a polyimide precursor and 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, it is biphenyltetracarboxylic dianhydride.

[0026] Examples of biphenyltetracarboxylic dianhydride include 3,3'-4,4'-biphenyltetracarboxylic dianhydride, 2,2'-3,3'-biphenyltetracarboxylic dianhydride, 2,3,3',4'-biphenyltetracarboxylic dianhydride, and 3,3',4,4'-diphenyl ether tetracarboxylic dianhydride. Preferably, 3,3'-4,4'-biphenyltetracarboxylic dianhydride is mentioned.

[0027] Biphenyltetracarboxylic dianhydride 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%, still 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 dianhydride component is, for example, 50 mol% or more, preferably 70 mol% or more, more preferably 80 mol% or more, still more preferably 90 mol% or more, particularly preferably 95 mol% or more, and most preferably 100 mol%.

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

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

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

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

[0034] Examples of the benzene tetracarboxylic dianhydride include benzene-1,2,4,5-tetracarboxylic dianhydride (also known as pyromellitic dianhydride). Examples of the benzophenone tetracarboxylic dianhydride include 3,3’-4,4’-benzophenone tetracarboxylic dianhydride. Examples of the biphenylsulfone tetracarboxylic dianhydride include 3,3’,4,4’-biphenylsulfone tetracarboxylic dianhydride. Examples of the naphthalene tetracarboxylic dianhydride 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 other acid dianhydride components, the molar fraction of the other acid dianhydride components 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%, still 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, still more preferably 10 mol% or less, particularly preferably 5 mol% or less, and most preferably 1 mol% or less.

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

[0039] <Diamine component> The diamine component includes 4-aminophenyl-4-aminobenzoate. Also, the diamine component does not include fluorine atoms and oxydianiline.

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

[0041]

Chemical formula

[0042] If the diamine component includes 4-aminophenyl-4-aminobenzoate, thermal expansion can be suppressed (the coefficient of thermal expansion can be lowered). Furthermore, thermal expansion during moisture absorption can be suppressed (the coefficient of thermal expansion during moisture absorption 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, still more preferably 20 mol% or more, and, for example, 90 mol% or less, preferably 70 mol% or less, more preferably 50 mol% or less, still 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 (the coefficient of thermal expansion can be lowered). Furthermore, thermal expansion during moisture absorption can be suppressed (the coefficient of hygrothermal expansion can be lowered). That is, the water absorption of the polyimide resin can be lowered.

[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, other diamine components also do not contain a fluorine atom and oxydianiline.

[0047] Examples of other diamine components include aromatic diamines having a plurality of aromatic rings (excluding those containing 4-aminophenyl-4-aminobenzoate, oxydianiline, and 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 those containing 4-aminophenyl-4-aminobenzoate, oxydianiline, and a fluorine atom) include, for example, in the above formula (1), 4,4'-diaminodiphenyl where Y is a single bond, bis(4-aminophenyl)sulfide where Y is -S-, 4,4'-diaminodiphenylethane where Y is -CH(CH3)-, 4,4'-diaminodiphenylpropane where Y is -C(CH3)2-, 4,4'-diaminobenzophenone where Y is CO-, 4,4'-diaminophenylenamine where Y is -NH-, and 4,4'-diaminobenzanilide where Y is -NHCO-.

[0049] The aromatic diamine having a plurality of aromatic rings does not contain oxydianiline. Specifically, the aromatic diamine having a plurality of aromatic rings does not contain oxydianiline in which Y is -O- (ether bond) in the above formula (1). Examples of oxydianiline include 3,4'-oxydianiline (alias: 3,4'-diaminodiphenyl ether), and 4,4'-oxydianiline (alias: 4,4'-diaminodiphenyl ether). 4,4'-oxydianiline may be simply abbreviated as ODA.

[0050] In oxydianiline, two aromatic rings are ether-bonded. Therefore, it has high water absorbency. That is, if the diamine component does not contain oxydianiline, the water absorbency of the polyimide resin can be further reduced.

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

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

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

[0054] Examples of phenylenediamine include o-phenylenediamine, m-phenylenediamine, and p-phenylenediamine. Preferably, p-phenylenediamine is mentioned. p-phenylenediamine may be simply abbreviated as PDA.

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

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

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

[0058] When the molar fraction of other diamine components 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 (the coefficient of thermal expansion can be lowered). Furthermore, expansion during moisture absorption can be suppressed (the coefficient of hygrothermal expansion can be lowered). That is, the water absorption of the polyimide resin can be lowered.

[0059] The diamine component does not contain a fluorine atom and oxydianiline, and contains 4-aminophenyl-4-aminobenzoate. The diamine component preferably does not contain a fluorine atom and oxydianiline, and contains 4-aminophenyl-4-aminobenzoate and p-phenylenediamine. The diamine component is more preferably composed 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 still 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, still more preferably 60 mol% or more, and, for example, 99 mol% or less, preferably 95 mol% or less, more preferably 90 mol% or less, still more preferably 80 mol% or less.

[0062] When 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%, still more preferably 90 mol% to 100 mol%, 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, still 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 at least the above lower limit value, thermal expansion can be suppressed (the coefficient of thermal expansion can be reduced). Further, thermal expansion during moisture absorption can be suppressed (the coefficient of hygrothermal expansion can be reduced). That is, the water absorption of the polyimide resin can be reduced. As a result, the wiring circuit board and the electronic device using the polyimide resin are excellent in 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 and 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 and a diamine component containing 4-aminophenyl-4-aminobenzoate and p-phenylenediamine in an organic solvent. Note that the diamine component does not contain a fluorine atom and oxydianiline.

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

[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. Further, 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 formulated such that the molar amount of the acid anhydride group (-CO-O-CO-) of the acid dianhydride component is equal to the molar amount of the amino group (-NH2) of the diamine component.

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

[0071] [Chemical formula]

[0072] [Chemical formula]

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

[0074] The solid content 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-mentioned polyamic acid, a photosensitizer, and a development accelerator. The polyimide precursor composition can form a pattern by photolithography and becomes a polyimide resin by heating.

[0076] [Polyamic acid] As described above, polyamic acid is a polyimide precursor. Further, polyamic acid forms a polyimide resin by the reaction (imidization reaction) of adjacent amide groups and carboxyl groups within the repeating unit to form a closed-ring structure containing imide groups. The imidization reaction proceeds, for example, by heating.

[0077] The content ratio of 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 still more preferably 90% by mass to 96% by mass.

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

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

[0080] <Photosensitizer> The photosensitizer is a component that promotes the imidization of polyamic acid in the portion (exposed portion) irradiated with light in the exposure step of the photolithography method (the portion where the imidization of polyamic acid is promoted has reduced solubility in the developer used in the development step after the exposure step). Therefore, the adhesion to the metal, which is the material of the wiring layer, can be improved.

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

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

[0083]

Chemical formula

[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 the pyridine-based photosensitizer represented by general formula (4) include 1-ethyl-3,5-dimethoxycarbonyl-4-(2-nitrophenyl)-4-hydroxypyridine, 1-methyl-3,5-dimethoxycarbonyl-4-(2-nitrophenyl)-4-hydroxypyridine, 1-propyl-3,5-dimethoxycarbonyl-4-(2-nitrophenyl)-4-hydroxypyridine, and 1-propyl-3,5-diethoxycarbonyl-4-(2-nitrophenyl)-4-hydroxypyridine.

[0086] Preferred examples of the pyridine-based photosensitizer include 1-ethyl-3,5-dimethoxycarbonyl-4-(2-nitrophenyl)-4-hydroxypyridine represented by the following formula (5).

[0087]

Chemical formula

[0088] The pyridine-based photosensitizer (1,4-dihydropyridine derivative) can be obtained, for example, by reacting a substituted benzaldehyde, an alkyl propiolate (alkyl propiolate) in a molar amount twice that thereof, and a predetermined primary amine under reflux in glacial acetic acid (Khim. Geterotsikl. Soed., pp. 1067-1071, 1982).

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

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

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

[0092] If the content ratio of the photosensitizer in the polyimide precursor composition (solid content) is equal to or lower than the above upper limit value, precipitation of the solid content during storage of the polyimide precursor composition can be suppressed, and furthermore, a decrease 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 compounding amount of the photosensitizer with respect to 100 parts by mass of the polyamic acid (solid content) is, for example, 0.1 part by mass to 15.0 parts by mass, preferably 0.5 part by mass to 10.0 parts by mass, more preferably 0.8 part by mass to 5.0 parts by mass, still more preferably 1.0 part by mass to 3.0 parts by mass, particularly preferably 1.2 parts by mass to 2.0 parts by mass.

[0094] The compounding amount of the photosensitizer with respect to 100 parts by mass of the polyamic acid (solid content) is, for example, 0.1 part by mass or more, preferably 0.5 part by mass or more, more preferably 0.8 part by mass or more, still more preferably 1.0 part by mass or more, particularly preferably 1.2 part by mass or more. Also, for example, it is 15.0 parts by mass or less, preferably 10.0 parts by mass or less, more preferably 5.0 parts by mass or less, still more preferably 3.0 parts by mass or less, particularly preferably 2.0 parts by mass or less.

[0095] <Developer accelerator> The developer accelerator promotes the dissolution of the unexposed portion (unexposed area) that has not received light irradiation in the exposure process of the photolithography method with respect to the developer in the development process.

[0096] Examples of the developer accelerator include ester compounds. Since the developer accelerator has an ester bond, for example, when a basic developer is used in the development process, the ester bond of the developer accelerator is hydrolyzed by the basic developer to generate alcohol and carboxylic acid. As a result, as the hydrophilicity increases, the basic developer becomes more likely to penetrate into the polyamic acid.

[0097] In this way, by using an ester compound, the permeability of the basic developer to the polyamic acid is improved, so that the unexposed portion can be more reliably removed in the development process. Therefore, the formed polyimide resin has excellent patterning accuracy.

[0098] The developer accelerator may be used alone or in combination of two or more.

[0099] Examples of the ester compound include a nitrogen-free ester compound and a nitrogen-containing ester compound. From the viewpoint of heat resistance, a nitrogen-free ester compound is preferably exemplified.

[0100] Examples of the nitrogen-free ester compound include an aromatic-ring-free nitrogen-free ester compound and an aromatic-ring-containing nitrogen-free ester compound, and preferably an aromatic-ring-containing nitrogen-free ester compound is exemplified.

[0101] Examples of the aromatic-ring-free nitrogen-free ester compound include a cyclic ester compound.

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

[0103] Examples of the aromatic-ring-containing nitrogen-free ester compound include an aromatic-ring-containing aliphatic carboxylic acid ester compound and an aromatic carboxylic acid ester compound. From the viewpoint of heat resistance, an aromatic carboxylic acid ester compound is preferably exemplified.

[0104] Examples of the aromatic-ring-containing aliphatic carboxylic acid ester compound include an aromatic-ring-containing acetic acid ester compound.

[0105] Examples of the aromatic-ring-containing acetic acid ester compound 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 the aromatic carboxylic acid ester compound include benzoic acid ester compounds, phthalic acid ester compounds, and trimellitic acid ester compounds. Preferably, benzoic acid ester compounds are included.

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

[0108] Examples of the benzoic acid ester compound also include 4-hydroxybenzoic acid (paraben) compounds represented by the following general formula (6).

[0109]

Chemical formula

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

[0111] Examples of the 4-hydroxybenzoic acid (paraben) compounds include butyl-4-hydroxybenzoate (butyl paraben) shown in the following formula (7). Further, for example, isobutyl-4-hydroxybenzoate (isobutyl paraben), hexyl-4-hydroxybenzoate (hexyl paraben), 2-methylpropyl-4-hydroxybenzoate, 2-ethylhexyl-4-hydroxybenzoate, and benzyl-4-hydroxybenzoate (benzyl paraben) are included.

[0112]

Chemical formula

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

[0114] Examples of the trimellitic acid ester compound include trimethyl trimellitate, tripropyl trimellitate, tributyl trimellitate, and tris(2-ethylhexyl) trimellitate.

[0115] Examples of the nitrogen-free ester compound preferably include benzoic acid ester compounds. More preferably, 4-hydroxybenzoic acid (paraben) compounds are included. Even more preferably, butyl-4-hydroxybenzoate (butyl paraben) is included.

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

[0117] Examples of the imide acrylate compound include, for example, N-acryloyloxyethyl hexahydrophthalimide, N-acryloyloxyethyl-1,2,3,6-tetrahydrophthalimide, and N-acryloyloxyethyl-3,4,5,6-tetrahydrophthalimide.

[0118] Examples of the development accelerator include, for example, 4-hydroxybenzoic acid compounds and imide acrylate compounds, and preferably 4-hydroxybenzoic acid compounds. Specifically, preferably, butyl-4-hydroxybenzoate (butyl paraben) is included as the development accelerator.

[0119] In the polyimide precursor composition (solid content), the content ratio of the development accelerator 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, particularly preferably 2.0% by mass to 5.0% by mass.

[0120] In the polyimide precursor composition (solid content), the content ratio of the development accelerator is, for example, 0.1% by mass or more, preferably 0.5% by mass or more, more preferably 1.0% by mass or more, still more preferably 1.5% by mass or more, 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, still more preferably 7.0% by mass or less, particularly preferably 5.0% by mass or less.

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

[0122] The compounding amount of the development accelerator with respect to 100 parts by mass of the polyamic acid (solid content) is, for example, 0.1 part by mass or more, preferably 0.5 part by mass or more, more preferably 1.0 part by mass or more, still more preferably 1.5 part by mass or more, particularly preferably 2.0 part 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, still more preferably 7.0 parts by mass or less, particularly preferably 5.0 parts by mass or less.

[0123] If the blending amount of the development accelerator is equal to or more than the above lower limit value with respect to 100 parts by mass of the polyamic acid (solid content), excessive progress of the imidization of the polyamic acid can be suppressed. Further, if the blending amount of the development accelerator is equal to or less than the above upper limit value with respect to 100 parts by mass of the polyamic acid (solid content), the compatibility is excellent and the development contrast can be improved.

[0124] The polyimide precursor composition may contain other components. Examples of the other components include amine compounds and photosensitizers.

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

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

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

[0128] The blending amount of the amine compound with respect to 100 parts by mass of the polyamic acid (solid content) is 0.01 part by mass to 10 parts by mass.

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

[0130] The compounding amount of the photosensitizer with respect to 100 parts by mass of the polyamic acid (solid content) is, for example, 0.05 part by mass 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 necessary. The polyimide precursor composition is preferably prepared by mixing a solution of the above-described polyamic acid, a photosensitizer, a development accelerator, and other components added as necessary, or the polyimide precursor composition is preferably prepared as a diluted solution (varnish) of the polyimide precursor composition by mixing the above-described polyamic acid, a photosensitizer, a development accelerator, and other components added as necessary in an organic solvent.

[0132] Examples of the organic solvent include aprotic polar solvents.

[0133] Examples of the aprotic polar solvent include N-methyl-2-pyrrolidone, dimethylacetamide, dimethyl sulfoxide, dimethylformamide, and hexamethylphosphoramide.

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

[0135] The content ratio 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, more preferably 10% by mass to 20% by mass.

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

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

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

[0139] The content ratio 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, still more preferably 0.12 mass% or more, 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, still more preferably 1.0 mass% or less, particularly preferably 0.50 mass% or less.

[0140] If the content ratio of the photosensitizer (solid content) in the diluted solution (varnish) of the polyimide precursor composition is not less than the above lower limit, in the polyimide precursor composition, imidization by heating of polyamic acid in the exposed portion is promoted, the solubility of the exposed portion in the developer is decreased, and a polyimide resin excellent in electrical characteristics can be formed. If the content ratio of the photosensitizer (solid content) in the diluted solution (varnish) of the polyimide precursor composition is not more than the above upper limit, a decrease in the thickness of the pattern of the polyimide resin can be suppressed in the heating step.

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

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

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

[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 above polyimide precursor composition. The polyimide resin is used, for example, as a coating layer of a wiring circuit board.

[0146] The moisture absorption coefficient of 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, particularly preferably 10.5 or less.

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

[0148] Note that the moisture absorption coefficient of 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) (average coefficient of thermal expansion from 100 °C to 250 °C) of the polyimide resin is, for example, 22.0 or less, preferably 21.0 or less, more preferably 20.0 or less, still more preferably 19.0 or less, and particularly preferably 18.0 or less.

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

[0151] Note that the coefficient of thermal expansion (CTE) (average coefficient of thermal expansion from 100 °C to 250 °C) of the polyimide resin 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 above upper limit value, the polyimide resin has an excellent dielectric constant.

[0154] Note that the initial dielectric constant of the polyimide resin at 10 GHz can be determined by using a PNA network analyzer (manufactured by Agilent Technologies) as the apparatus and by the Split Post dielectric resonator (SPDR) method.

[0155] The dielectric constant of the polyimide resin after 24-hour immersion at 10 GHz 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, particularly preferably 3.5 or less.

[0156] If the dielectric constant of the polyimide resin after 24-hour immersion at 10 GHz is equal to or less than the above upper limit value, the polyimide resin has low hygroscopicity and can suppress the increase in dielectric constant due to moisture absorption.

[0157] Note that the dielectric constant of the polyimide resin after 24-hour immersion is the dielectric constant measured after immersing the polyimide resin in pure water at 25 °C for 24 hours, then taking it out of the pure water, wiping off the water droplets on the surface, and then measuring. For the measurement, a PNA network analyzer (manufactured by Agilent Technologies) can be used, and the dielectric constant after 24-hour immersion at 10 GHz can be obtained by the Split Post Dielectric Resonator (SPDR) method.

[0158] The initial dielectric tangent (tanδ) 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, still more preferably 0.009 or less.

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

[0160] Note that the initial dielectric tangent (tanδ) of the polyimide resin at 10 GHz can be obtained by the method described in the examples below.

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

[0162] If the dielectric tangent (tanδ) of the polyimide resin after 24-hour immersion at 10 GHz is equal to or less than the above upper limit value, the polyimide resin has low hygroscopicity and can suppress an increase in the dielectric tangent (dielectric loss) due to moisture absorption.

[0163] The dielectric tangent (tanδ) of the polyimide resin after 24-hour immersion can be determined by the method described in the examples below.

[0164] The difference between the dielectric tangent (tanδ) of the polyimide resin after 24-hour immersion at 10 GHz and the initial dielectric tangent (tanδ) of the polyimide resin (the dielectric tangent (tanδ) of the polyimide resin after 24-hour immersion - the initial dielectric tangent (tanδ) of the polyimide resin) is, for example, 0.006 or less, preferably 0.005 or less, more preferably 0.004 or less, still more preferably 0.003 or less, particularly preferably 0.001 or less.

[0165] If the difference between the dielectric tangent (tanδ) of the polyimide resin after 24-hour immersion at 10 GHz and the initial dielectric tangent (tanδ) of the polyimide resin is equal to or less than the above upper limit value, the polyimide resin has low hygroscopicity and can suppress an increase in the dielectric tangent (dielectric loss) due to moisture absorption. As a result, the wiring circuit board and the electronic device using this polyimide resin are excellent in reliability.

[0166] 4. Wiring Circuit Board The wiring 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 above-described polyimide precursor composition.

[0167] Examples of the shape of the base material include a film shape having a predetermined thickness (including a sheet shape) and a plate shape.

[0168] Examples of the material of the base material include metals. Preferably, aluminum, stainless steel, and copper are mentioned. More preferably, stainless steel is mentioned.

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

[0170] The material of the insulating layer is not particularly limited, and known materials can be used. Preferably, the material of the insulating layer is a polyimide resin. In addition, the polyimide resin formed from the above-mentioned polyimide precursor composition may be used.

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

[0172] Examples of the material of the wiring layer include metals. Preferably, chromium and copper are included. More preferably, copper is included.

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

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

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

[0176] First, as shown in FIG. 1A, an insulating layer material (e.g., a polyimide precursor composition) is applied onto a substrate S and cured to form an insulating layer 10. Further, as an underlayer, a wiring layer material made of metal is laminated by sputtering to form a metal layer 21. In addition, after forming a plating resist 30 having a shape of an inverse pattern to a predetermined wiring pattern using a dry film resist, a conductor pattern 20 (wiring layer) having the predetermined wiring pattern is formed on the portion of the metal layer 21 where the plating resist is not formed by semi-additive method (lamination step).

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

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

[0179] Examples of the coating 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 film 50A is, for example, 1 μm to 50 μm, preferably 10 μm to 40 μm.

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

[0183] Note that a metal underlayer may be formed before applying the diluted solution (varnish) of the polyimide precursor composition. Specifically, after the etching step, the metal underlayer may be formed by metal plating. Examples of the material of 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] Next, as shown in FIG. 1D, the film 40A is irradiated with ultraviolet rays through the photomask M (exposure step). The photomask M has an opening Ma corresponding to the pattern shape of the conductor pattern 20 (wiring layer).

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

[0186] By irradiating the film 40A with ultraviolet rays through the photomask M, an exposed portion 41 and an unexposed portion 42 are formed in the film 40A. Note that after the ultraviolet ray 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 film 40A is developed. Specifically, the unexposed portion 42 of the film 40A is dissolved and removed by the developer (development step). After development, the exposed portion 41 is heated. As a result, a polyimide resin is formed on the exposed portion 41 of the film 40A, and a coating layer 40B is formed.

[0189] Examples of the developer include basic developers. Examples of the basic developer include inorganic alkali solutions and organic alkali solutions. Examples of the inorganic alkali solution include aqueous sodium hydroxide solution and aqueous potassium hydroxide solution. Examples of the organic alkali solution include aqueous solution of tetramethylammonium hydroxide (TMAH) and TMAH / Ekenen solution, and preferably TMAH / Ekenen solution. Here, Ekenen is a mixed solvent mainly composed of ethanol.

[0190] Examples of the development method include dipping method, spraying method, and paddle 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] As described above, a laminate including an insulating layer 10, a conductor pattern 20 (wiring layer) having a predetermined pattern shape, and a coating layer 40B made of polyimide resin covering the conductor pattern 20 (wiring layer) is formed on the base material S. Thereby, the wiring circuit board 1 is obtained.

[0193] 5. Electronic device The electronic device of the present invention includes the above wiring circuit board.

[0194] Examples of the electronic device include a notebook personal computer, a smartphone, and the like.

[0195] (Function and effect) The polyamic acid of the present invention is a reaction product of an acid dianhydride component and a diamine component. The acid dianhydride component includes biphenyltetracarboxylic dianhydride, the diamine component does not include a fluorine atom and oxydianiline, and includes 4-aminophenyl-4-aminobenzoate. Therefore, while having low water absorption, the environmental load can be reduced.

[0196] Specifically, in the polyimide precursor composition of the present invention, the diamine component does not contain a fluorine atom. Therefore, the environmental load can be reduced. Further, the diamine component does not contain oxydianiline and contains 4-aminophenyl-4-aminobenzoate. Therefore, even without containing a fluorine atom, the water absorption can be reduced. As a result, a polyimide resin having low water absorption and capable of reducing the environmental load can be formed.

[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. Therefore, it is possible to manufacture a wiring circuit board and an electronic device that are excellent in reliability and can reduce the environmental load.

Examples

[0198] Examples, comparative examples, and reference examples are shown below to more specifically explain the present invention. Note that the present invention is not limited to any of the examples, comparative examples, and reference examples. Further, specific numerical values such as the blending ratio (content), physical property values, parameters, etc. used in the following description can be replaced with the upper limit (numerical values defined as "hereinafter", "less than") or the lower limit (numerical values defined as "above", "exceeding") of the corresponding blending ratio (content), physical property values, parameters, etc. described in the above "Mode 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 will be described in detail.

[0200] BPDA: 3,3’,4,4’-Biphenyltetracarboxylic dianhydride PPD: 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-hydroxypyridine n-BP: Butyl-4-hydroxybenzoate

[0201] <Synthesis of polyamic acid> Preparation Example 1 In a 300 mL four-necked 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 heating to 60°C. Thereby, an NMP solution containing the polyamic acid of Preparation Example 1 was obtained. The synthesized polyamic acid contains the above-mentioned first structural unit and second structural unit. In addition, in this polyamic acid, the proportion of the first structural unit is 5 mol%, and the proportion of the second structural unit is 95 mol%.

[0202] Preparation Examples 2 to 5, Comparative Preparation Examples 1 and 2 Except for changing the type and blending ratio of the diamine component so as to obtain the composition ratios shown in Table 1, the polyamic acids of each example and each comparative example were prepared in the same manner as the polyamic acid of Preparation Example 1. Note that in Comparative Preparation Example 1, APAB is not included and TFMB is included. In addition, in Comparative Preparation Example 2, APAB is not included and ODA is included.

[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. Note that the polyimide precursor composition was prepared by mixing so that the composition ratio (mass ratio) of the above polyamic acid (solid content), NKS-4 (photosensitizer), and n-BP (development accelerator) was 95.4:1.5:3.1. Thereby, an NMP solution (varnish) of the polyimide precursor composition of Example 1 was obtained.

[0204] <Production of polyimide resin film> The solution (varnish) of the above polyimide precursor composition 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) under the conditions of 1100 rpm for 30 seconds, and then heat-dried at 130 °C for 5 minutes using an explosion-proof dryer (trade name: SPHH-201, manufactured by Espec) to form a film (thickness 28 μm) composed of the polyimide precursor composition of Example 1. Next, this film was irradiated with ultraviolet light (wavelength 365 nm, 400 mJ / cm 2 ) using a simple exposure machine (trade name: UV-2001M-ND, manufactured by CES), and heated at 185 °C for 5 minutes using a blow dryer (trade name: DRM320DA, manufactured by Advantech). Furthermore, using a laboratory curing furnace (trade name: Infrared Heating System E42327, manufactured by Noritake), heating was carried out under the condition that the target temperature was 360 °C to cure (imidize) it, and a film-like polyimide resin with a thickness of 20 μm was produced on the substrate. Then, by removing the substrate, the polyimide resin of Example 1 was obtained.

[0205] Examples 2 to 4 Except for using the polyamic acid shown in Table 2, the polyimide precursor compositions of each example were prepared in the same manner as the polyimide precursor composition of Example 1, and film-like polyimide resins (thickness: 20 μm) were produced.

[0206] Comparative Examples 1 to 3 Except for using the polyamic acid and development accelerator shown in Table 2 and changing the composition ratio of each component in the polyimide precursor composition, the polyimide precursor compositions of each comparative example were prepared in the same manner as the polyimide precursor composition of Example 1, and film-like polyimide resins (thickness: 20 μm) were produced.

[0207] Reference Examples 1 to 4 The polyamic acid shown in Table 3 was used as the polyimide precursor composition of each reference example without blending a photosensitizer and a development accelerator, and a film-like polyimide resin (thickness: 20 μm) was produced.

[0208] <Evaluation> [Environmental load] In the polyimide resins of each example, each comparative example, and each reference example, the environmental load was evaluated according to the following criteria. The results are shown in Tables 2 and 3.

[0209] {Criteria} 〇: The polyimide resin does not contain fluorine atoms. ×: The polyimide resin contains fluorine atoms.

[0210] [Coefficient of hygrothermal expansion (CHE)] The polyimide resins (thickness: 20 μm) of each example, each comparative example, and each reference example were cut into pieces with a width of 5 mm and a length of 1.5 mm to prepare samples for measuring the coefficient of hygrothermal expansion (CHE). Each sample was mounted on the chuck of a humidity-controlled TMA (trade name: HC-TMA400SA, manufactured by Bruker). Under the constant temperature condition of 30 °C, a tensile method with a load of 20 g was used to humidify from 5% RH to 75% RH, and the coefficient of hygrothermal expansion (CHE) of each polyimide resin was determined with the elongation after 5 hours at 75% RH as the maximum elongation point. Regarding the coefficient of hygrothermal expansion (CHE), it 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 were shown and they were not evaluated according to the following criteria.

[0211] {Criteria} ◎: 10 or less 〇: Exceeding 10 and 12 or less ×: Exceeding 12

[0212] [Coefficient of thermal expansion (CTE)] The polyimide resins (thickness: 20 μm) of each example, each comparative example, and each reference example were cut into a size of 5 mm in width and 1.5 mm in length to prepare samples 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 while applying a load of 50 mN, the temperature was raised from 25°C to 250°C at a rate of 5°C / min. 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 the numerical values were shown and they were not evaluated according to the following criteria.

[0213] {Criteria} ◎: 18 or less 〇: Exceeding 18 and 20 or less ×: Exceeding 20

[0214] [Difference in dielectric loss tangent (tanδ)] For the polyimide resins (thickness: 20 μm) of each example, each comparative example, and each reference example, the initial dielectric loss tangent (tanδ) at 10 GHz was determined. As the apparatus, a PNA network analyzer (manufactured by Agilent Technologies) was used, and it was determined by the Split Post dielectric resonator (SPDR) method.

[0215] Next, the polyimide resins of each example, each comparative example, and each reference example were immersed in pure water at 25°C for 24 hours. Then, each polyimide resin was taken out of the pure water, the water droplets on the surface were wiped off, and immediately, the dielectric loss tangent (tanδ) after 24-hour immersion at 10 GHz was determined by a PNA network analyzer (manufactured by Agilent Technologies).

[0216] And the difference between the initial dielectric loss tangent (tanδ) and the dielectric loss tangent (tanδ) after 24-hour immersion (dielectric loss tangent (tanδ) after 24-hour immersion - initial dielectric loss tangent (tanδ)) 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 the numerical values were shown and they were not evaluated according to the following criteria.

[0217] {Criteria} ◎: 0.001 or less ○: More than 0.001 and 0.003 or less △: More than 0.003 and 0.005 or less ×: More than 0.005

[0218]

Table 1

[0219]

Table 2

[0220]

Table 3

Explanation of Symbols

[0221] 1 Wiring Circuit Board S Substrate 10 Insulation Layer 20 Conductor Pattern (Wiring Layer) 21 Metal Layer 22 Copper Plating 30 Plating Resist 40A Film 40B Coating 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, the diamine component does not include a fluorine atom and oxydianiline, and includes 4-aminophenyl-4-aminobenzoate, a polyamic acid.

2. 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. The polyamic acid according to Claim 1.

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

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

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

6. The photosensitizer is a pyridine-based photosensitizer. The polyimide precursor composition according to Claim 5.

7. The development accelerator is 4-hydroxybenzoic acids. The polyimide precursor composition according to Claim 5.

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

9. A wiring circuit board including the polyimide resin according to Claim 8.

10. An electronic device including the wiring circuit board according to Claim 9.

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