Photosensitive polyimide precursor composition, polyimide resin, wiring circuit board, and electronic device

Abstract

To provide a photosensitive polyimide precursor composition having low water absorption while reducing environmental load, a polyimide resin, a wiring circuit board, and electronic equipment.SOLUTION: The photosensitive polyimide precursor composition contains a polyamic acid and a photosensitizer. The polyamic acid is a reaction product of an acid dianhydride component including biphenyltetracarboxylic dianhydride and a diamine component including p-phenylenediamine and fluorine-free biphenyl-type diamine.SELECTED DRAWING: None

Description

[Technical Field]

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

[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] As a material for the insulating layer and the covering layer used in such a wiring circuit board, for example, a photosensitive polyimide precursor composition is known (see, for example, Patent Document 1 below).

[0004] Specifically, Example 1 of Cited Document 1 discloses a photosensitive polyimide precursor composition containing a polyamic acid that is a reaction product of 3,3',4,4'-biphenyltetracarboxylic dianhydride (BPDA) as an acid anhydride component, p-phenylenediamine (PPD) and 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl (TFMB) as diamine components, 1-ethyl-3,5-dimethoxycarbonyl-4-(2-nitrophenyl)-4-hydropyridine as a photosensitizer, and n-acryloyloxyethylhexahydrophthalimide as a development accelerator. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-100441 Summary of the Invention [Problem to be solved by the invention]

[0006] However, from the viewpoint of reducing the environmental load, there is a demand for a photosensitive polyimide precursor composition that does not contain fluorine.

[0007] Furthermore, since the photosensitive polyimide precursor composition is used as a material for the insulating layer and the covering layer used in the wiring circuit board, there is a risk that the absorption of moisture in the air will cause dimensional changes and deteriorate the properties of the wiring circuit board.

[0008] The present invention provides a photosensitive polyimide precursor composition, a polyimide resin, a wiring circuit board, and an electronic device that have low water absorption while reducing the environmental load. [Means for solving the problem]

[0009] The present invention [1] provides a photosensitive polyimide precursor composition comprising a polyamic acid and a photosensitizer, wherein the polyamic acid is a reaction product of an acid dianhydride component and a diamine component, the acid dianhydride component comprising biphenyltetracarboxylic dianhydride, and the diamine component comprising p-phenylenediamine and a fluorine-free biphenyl-type diamine.

[0010] The present invention [2] includes the photosensitive polyimide precursor composition according to the above [1], in which the photosensitizer is a pyridine-based photosensitizer.

[0011] The present invention [3] includes the photosensitive polyimide precursor composition according to the above [1] or [2], in which the content of the photosensitizer in the photosensitive polyimide precursor composition (solid content) is 10.0 mass % or less.

[0012] The present invention [4] includes the photosensitive polyimide precursor composition according to any one of the above [1] to [3], which further contains a development accelerator.

[0013] The present invention [5] includes the photosensitive polyimide precursor composition according to the above [4], in which the development accelerator comprises a benzoate compound.

[0014] The present invention [6] includes the photosensitive polyimide precursor composition according to the above [5], in which the benzoic acid ester compound is a paraben.

[0015] The present invention [7] includes the photosensitive polyimide precursor composition according to the above [6], in which the parabens are butylparaben.

[0016] The present invention [8] includes the photosensitive polyimide precursor composition according to any one of the above [4] to [7], wherein the content of the development accelerator in the photosensitive polyimide precursor composition (solid content) is 35.0 mass % or less.

[0017] The present invention [9] includes the photosensitive polyimide precursor composition according to any one of the above [1] to [8], wherein the content of the fluorine-free biphenyl-type diamine in the diamine component is 20 mol % or more and 60 mol % or less.

[0018] The present invention

[10] includes a polyimide resin that is a cured product of the photosensitive polyimide precursor composition according to any one of the above [1] to [9].

[0019] The present invention

[11] includes a wiring circuit board containing the polyimide resin described in

[10] above.

[0020] The present invention

[12] includes an electronic device including the printed circuit board described in

[11] above. [Effects of the Invention]

[0021] The photosensitive polyimide precursor composition of the present invention comprises a polyamic acid and a photosensitizer, the polyamic acid being a reaction product of an acid dianhydride component and a diamine component, the acid dianhydride component including biphenyltetracarboxylic dianhydride, and the diamine component including p-phenylenediamine and a fluorine-free biphenyl-type diamine, thereby reducing the environmental impact and exhibiting low water absorption.

[0022] The polyimide resin of the present invention is formed from the photosensitive polyimide precursor composition of the present invention, and therefore has low water absorption while reducing the environmental load.

[0023] The wired circuit board of the present invention contains the polyimide resin of the present invention. Therefore, the environmental impact can be reduced. Furthermore, the low water absorption of the polyimide resin suppresses dimensional changes due to moisture, thereby improving reliability.

[0024] The electronic device of the present invention includes the wired circuit board of the present invention. Therefore, the environmental impact can be reduced. Furthermore, the low water absorption suppresses dimensional changes due to moisture, and reliability is improved. [Brief explanation of the drawings]

[0025] [Figure 1] 1A to 1E show an example of a method for forming an insulating layer made of a polyimide resin from the photosensitive polyimide precursor composition of the present invention, where Fig. 1A shows the coating step, Fig. 1B shows the drying step, Fig. 1C shows the exposure step, Fig. 1D shows the development step, and Fig. 1E shows the heating step. DETAILED DESCRIPTION OF THE INVENTION

[0026] 1. Photosensitive polyimide precursor composition The photosensitive polyimide precursor composition of the present invention contains a polyamic acid and a photosensitizer. The photosensitive polyimide precursor composition preferably further contains a development accelerator. The photosensitive polyimide precursor composition can be patterned by photolithography and becomes a polyimide resin by heating.

[0027] <Polyamic acid> Polyamic acid is a polyimide precursor, a reaction product of an acid dianhydride component and a diamine component. In polyamic acid, adjacent amide groups and carboxyl groups in the repeating unit react (imidization reaction) to form an imide-group-containing closed ring structure, thereby forming a polyimide resin. The imidization reaction proceeds, for example, by heating.

[0028] [Acid dianhydride component] The acid dianhydride component contains biphenyltetracarboxylic dianhydride from the viewpoint of mechanical strength, and preferably consists of biphenyltetracarboxylic dianhydride.

[0029] 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. 3,3'-4,4'-biphenyltetracarboxylic dianhydride is preferred. 3,3'-4,4'-biphenyltetracarboxylic dianhydride is sometimes abbreviated as BPDA.

[0030] The acid dianhydride component may contain an acid dianhydride component other than biphenyltetracarboxylic dianhydride, but preferably does not contain an acid dianhydride component other than biphenyltetracarboxylic dianhydride.

[0031] Examples of other acid dianhydride components include aliphatic tetracarboxylic dianhydrides and aromatic tetracarboxylic dianhydrides (excluding biphenyltetracarboxylic dianhydride). Examples of aliphatic tetracarboxylic dianhydrides include cyclopentanetetracarboxylic dianhydride and tricarboxycyclopentylacetic dianhydride. Examples of aromatic tetracarboxylic dianhydrides (excluding biphenyltetracarboxylic dianhydride) include benzenetetracarboxylic dianhydride, benzophenonetetracarboxylic dianhydride, biphenylsulfonetetracarboxylic dianhydride, and naphthalenetetracarboxylic dianhydride.

[0032] Examples of benzenetetracarboxylic dianhydrides include benzene-1,2,4,5-tetracarboxylic dianhydride (also known as pyromellitic dianhydride). Examples of benzophenone tetracarboxylic dianhydrides include 3,3'-4,4'-benzophenone tetracarboxylic dianhydride. Examples of biphenylsulfone tetracarboxylic dianhydrides 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.

[0033] [Diamine component] The diamine component includes p-phenylenediamine and a fluorine-free biphenyl-type diamine. The diamine component preferably consists of p-phenylenediamine and a fluorine-free biphenyl-type diamine. p-Phenylenediamine is sometimes abbreviated as PDA.

[0034] If the diamine component contains p-phenylenediamine and a fluorine-free biphenyl type diamine, it is possible to form a polyimide resin having low water absorption while reducing the environmental load.

[0035] Examples of fluorine-free biphenyl-type diamines include compounds (benzidine derivatives) represented by the following general formula (1).

[0036] [ka]

[0037] In general formula (1), each of R1 to R8 is one selected from the group consisting of a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, and an alkoxy group having 1 to 4 carbon atoms. A hydrogen atom or an alkyl group having 1 to 4 carbon atoms is preferred. A hydrogen atom or a methyl group is more preferred. None of R1 to R8 contains a fluorine atom.

[0038] In general formula (1), R1 to R8 may be the same as or different from each other.

[0039] Examples of fluorine-free biphenyl-type diamines (benzidine derivatives) represented by general formula (1) include benzidine, 3,3'-dimethylbenzidine (o-tolidine), 2,2'-dimethylbenzidine (m-tolidine), 3,3'-dimethoxybenzidine, and 2,2'-dimethoxybenzidine. 3,3'-dimethylbenzidine (o-tolidine) and 2,2'-dimethylbenzidine (m-tolidine) are preferred. 2,2'-dimethylbenzidine (m-tolidine) represented by the following formula (2) is more preferred. m-tolidine is sometimes abbreviated as m-TD.

[0040] [ka]

[0041] If the diamine component contains m-tolidine, a polyimide resin having even lower water absorption can be formed.

[0042] The diamine component may contain other diamine components other than p-phenylenediamine and fluorine-free biphenyl-type diamine. Preferably, it does not contain other diamine components other than p-phenylenediamine and fluorine-free biphenyl-type diamine. Note that the other diamine components preferably do not contain fluorine.

[0043] That is, the diamine component is preferably a non-fluorine-containing diamine component.

[0044] Examples of other diamine components include aromatic diamines (excluding p-phenylenediamine and fluorine-free biphenyl-type diamines) and aliphatic diamines. Examples of aromatic diamines (excluding p-phenylenediamine and fluorine-free biphenyl-type diamines) include aromatic diamines having a single aromatic ring (excluding p-phenylenediamine) and aromatic diamines having multiple aromatic rings (excluding fluorine-free biphenyl-type diamines).

[0045] Examples of aromatic diamines having a single aromatic ring (excluding p-phenylenediamine) include o-phenylenediamine, m-phenylenediamine, phenylenediamine derivatives, and xylylenediamine. Examples of phenylenediamine derivatives include phenylenediamines to which an alkyl group is bonded. Examples of phenylenediamine derivatives include 4-methyl-1,2-phenylenediamine, 4-methyl-1,3-phenylenediamine, 4,5-dimethyl-1,2-phenylenediamine, 2,5-dimethyl-1,4-phenylenediamine, and 2,4,6-trimethyl-1,3-phenylenediamine. Examples of xylylenediamines include m-xylylenediamine and o-xylylenediamine.

[0046] Examples of aromatic diamines having multiple aromatic rings (excluding fluorine-free biphenyl-type diamines) include 4,4'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 3,3'-diaminodiphenyl ether, 4,4'-diaminodiphenylpropane, 3,3'-diaminodiphenylpropane, 4,4'-diaminophenylmethane, 3,3'-diaminodiphenylmethane, 4,4'-diaminodiphenyl sulfide, 3,3'-diaminodiphenyl sulfide, 4,4'-diaminodiphenyl sulfone, 3,3'-diaminodiphenyl sulfone, 1,4-bis(4-aminophenoxy)benzene, 1,3-bis(4-aminophenoxy)benzene, 1,3-bis(3-aminophenoxy)benzene, 1,3-bis(4-aminophenoxy)-2,2-dimethylpropane, and 4,4'-diaminobenzophenone.

[0047] Aliphatic diamines include, for example, hexamethylenediamine, 1,8-diaminooctane, 1,12-diaminododecane, and 1,3-bis(3-aminopropyl)-1,1,3,3-tetramethyldisiloxane.

[0048] The content (molar fraction) of p-phenylenediamine in the diamine component is, for example, 20 mol% to 90 mol%, preferably 30 mol% to 80 mol%, more preferably 40 mol% to 75 mol%, and even more preferably 50 mol% to 70 mol%.

[0049] The content (molar fraction) of p-phenylenediamine in the diamine component is, for example, 20 mol% or more, preferably 30 mol% or more, more preferably 40 mol% or more, even more preferably 50 mol% or more, and for example, 90 mol% or less, preferably 80 mol% or less, more preferably 75 mol% or less, even more preferably 70 mol% or less.

[0050] The content (molar fraction) of the fluorine-free biphenyl-type diamine in the diamine component is, for example, 10 mol% to 80 mol%, preferably 20 mol% to 70 mol%, more preferably 25 mol% to 60 mol%, and even more preferably 30 mol% to 50 mol%.

[0051] The content (molar fraction) of fluorine-free biphenyl-type diamine in the diamine component is, for example, 10 mol% or more, preferably 20 mol% or more, more preferably 25 mol% or more, even more preferably 30 mol% or more, and for example, 80 mol% or less, preferably 70 mol% or less, more preferably 60 mol% or less, even more preferably 50 mol% or less.

[0052] When the content ratio (molar fraction) of p-phenylenediamine and fluorine-free biphenyl-type diamine in the diamine component is within the above range, a polyimide resin having low water absorption can be formed even though the diamine component does not contain fluorine. In other words, a polyimide resin having low water absorption can be formed while reducing the environmental load.

[0053] 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 p-phenylenediamine and a fluorine-free biphenyl-type diamine 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 p-phenylenediamine and m-tolidine in an organic solvent.

[0054] The reaction temperature between the acid dianhydride component and the diamine component is, for example, 10° C. to 150° 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.

[0055] The acid dianhydride component and the diamine component are blended so that the molar amount of the acid anhydride groups (-CO-O-CO-) of the acid dianhydride component is equal to the molar amount of the amino groups (-NH2) of the diamine component.

[0056] As described above, 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.

[0057] 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.

[0058] The polyamic acid includes, for example, a first structural unit represented by the following formula (3). Preferably, the polyamic acid includes a first structural unit represented by the following formula (3) and a second structural unit represented by the following formula (4). More specifically, if the acid dianhydride component includes 3,3'-4,4'-biphenyltetracarboxylic dianhydride and the diamine component includes p-phenylenediamine, the polyamic acid includes the first structural unit represented by the following formula (3). Also, if the acid dianhydride component includes 3,3'-4,4'-biphenyltetracarboxylic dianhydride and the diamine component includes m-tolidine, the polyamic acid includes a second structural unit represented by the following formula (4).

[0059] [ka]

[0060] [ka]

[0061] The content of polyamic acid (solid content) in the photosensitive polyimide precursor composition (solid content) is, for example, 45 mass% or more, preferably 50 mass% or more, more preferably 55 mass% or more, even more preferably 60 mass% or more, particularly preferably 70 mass% or more, and for example, 95 mass% or less, preferably 90 mass% or less, more preferably 85 mass% or less, even more preferably 80 mass% or less.

[0062] When the content of polyamic acid (solid content) in the photosensitive polyimide precursor composition (solid content) is within the above range, the content of the photosensitizer described below can be adjusted to an appropriate range, and appropriate photolithography properties can be obtained.

[0063] <Photosensitizer> The photosensitizer is a component that promotes the imidization of polyamic acid in the area irradiated with light (exposed area) during the exposure step of the photolithography method (the area where the imidization of polyamic acid is promoted becomes less soluble in the developer used in the development step that follows the exposure step).

[0064] Examples of photosensitizers include photosensitizers having a nitrogen-containing heterocycle, which has a nitrogen atom as a heteroatom contained in the atoms constituting the heterocycle.

[0065] Examples of nitrogen-containing heterocycles include nitrogen-containing aromatic heterocycles and nitrogen-containing alicyclic heterocycles. Nitrogen-containing aromatic heterocycles are those having a nitrogen atom as a heteroatom contained in the atoms constituting the aromatic heterocycle. Nitrogen-containing alicyclic heterocycles are those having a nitrogen atom as a heteroatom contained in the atoms constituting the alicyclic heterocycle.

[0066] Nitrogen-containing aromatic heterocycles include, for example, pyrrole, imidazole, pyrazole, pyridine, pyridazine, pyrazine, pyrimidine, triazole, and triazine.

[0067] The nitrogen-containing aromatic heterocycle has only nitrogen as a heteroatom, but may have nitrogen and other heteroatoms other than nitrogen. Examples of other heteroatoms include oxygen and sulfur. Examples of such nitrogen-containing aromatic heterocycles include oxazole, isoxazole, thiazole, and isothiazole.

[0068] The nitrogen-containing aromatic heterocycle may have one heterocycle or may have multiple heterocycles. Examples of such nitrogen-containing aromatic heterocycles include quinoline, isoquinoline, quinazoline, quinoxaline, naphthyridine, carbazole, phenanthridine, and phenanthroline.

[0069] Nitrogen-containing alicyclic heterocycles include, for example, pyrroline, pyrrolidine, imidazoline, imidazolidine, pyrazoline, pyrazolidine, piperidine, and piperazine.

[0070] The nitrogen-containing alicyclic heterocycle has only nitrogen as a heteroatom, but may have nitrogen and other heteroatoms other than nitrogen. Examples of other heteroatoms include oxygen and sulfur. Examples of such nitrogen-containing alicyclic heterocycles include oxazolidine, isoxazolidine, thiazolidine, isothiazolidine, morpholine, and thiomorpholine.

[0071] The nitrogen-containing aromatic heterocycle may have one heterocycle or multiple heterocycles, such as indole, indoline, and indazole.

[0072] Examples of photosensitizers include photosensitizers having a nitrogen-containing heterocycle. Preferred examples include photosensitizers having a nitrogen-containing aromatic heterocycle and photosensitizers having a nitrogen-containing alicyclic heterocycle. More preferred examples include photosensitizers having a nitrogen-containing aromatic heterocycle having only nitrogen atoms as heteroatoms and photosensitizers having a nitrogen-containing alicyclic heterocycle having only nitrogen atoms as heteroatoms. Even more preferred examples include photosensitizers having pyridine (pyridine-based photosensitizers) and photosensitizers having piperidine (piperidine-based photosensitizers). Particularly preferred examples include pyridine-based photosensitizers.

[0073] Examples of pyridine-based photosensitizers include compounds (1,4-dihydropyridine derivatives) represented by the following general formula (5): In general formula (5), R9, R10, R11, R12, and R13 each represent a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and may be the same or different from one another. Also, in general formula (5), Ar1 represents an aryl group having a nitro group at the ortho position.

[0074] [ka]

[0075] In general formula (5), R9 is, for example, a hydrogen atom or a methyl group. R10 is, for example, a hydrogen atom or a methyl group. R11 is, for example, a methyl group or an ethyl group. R12 is, for example, a methyl group or an ethyl group. R13 is, for example, a methyl group or an ethyl group. Ar1 is, for example, a 2-nitrophenyl group.

[0076] Examples of pyridine-based photosensitizers represented by general formula (5) 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.

[0077] A preferred example of the pyridine-based photosensitizer is 1-ethyl-3,5-dimethoxycarbonyl-4-(2-nitrophenyl)-4-hydropyridine represented by the following formula (6).

[0078] [ka]

[0079] 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 (alkyl propargylic acid ester) and a specific primary amine in glacial acetic acid under reflux (Khim. Geterotsikl. Soed., pp. 1067-1071, 1982).

[0080] An example of a piperidine-based photosensitizer is a compound represented by the following general formula (7): In general formula (7), R14 and R15 each represent a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and may be the same as or different from each other. Also, in general formula (7), Ar2 represents an aryl group.

[0081] [ka]

[0082] In the general formula (7), R14 is, for example, a methyl group, R15 is, for example, a methyl group, and Ar2 is, for example, a 2-nitro-4,5-methoxyphenyl group.

[0083] A preferred example of the piperidine-based photosensitizer is N-{[(4,5-dimethoxy-2-nitrobenzyl)oxy]carbonyl}2,6-dimethylpiperidine represented by the following formula (8).

[0084] [ka]

[0085] The content of the photosensitizer in the photosensitive polyimide precursor composition (solid content) is, for example, 0.1 mass % to 15 mass %, preferably 1.0 mass % to 13.0 mass %, more preferably 3.0 mass % to 12.0 mass %, even more preferably 5.0 mass % to 11.0 mass %, and particularly preferably 6.5 mass % to 10.0 mass %.

[0086] The content of the photosensitizer in the photosensitive polyimide precursor composition (solid content) is, for example, 0.1 mass% or more, preferably 1.0 mass% or more, more preferably 3.0 mass% or more, even more preferably 5.0 mass% or more, particularly preferably 6.5 mass% or more, and for example, 15 mass% or less, preferably 13.0 mass% or less, more preferably 12.0 mass% or less, even more preferably 11.0 mass% or less, particularly preferably 10.0 mass% or less.

[0087] When the content of the photosensitizer in the photosensitive polyimide precursor composition (solid content) is equal to or greater than the lower limit, photolithography properties can be ensured, and the solubility of the exposed portion in the developer can be sufficiently reduced. When the content of the photosensitizer in the photosensitive polyimide precursor composition (solid content) is equal to or less than the upper limit, precipitation of the solid content can be suppressed during storage of the photosensitive polyimide precursor composition. Furthermore, reduction in the thickness of the polyimide resin formed can be suppressed in the heat curing step after the development step in the photolithography method.

[0088] 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 1.0 parts by mass or more, more preferably 3.0 parts by mass or more, even more preferably 4.0 parts by mass or more, particularly preferably 5.0 parts by mass or more, and for example, 20 parts by mass or less, preferably 18 parts by mass or less, more preferably 16 parts by mass or less, even more preferably 14 parts by mass or less, particularly preferably 12 parts by mass or less.

[0089] <Development accelerator> The development accelerator promotes dissolution of the portion not irradiated with light in the exposure step of the photolithography method (unexposed portion) in the developer in the development step.

[0090] The development accelerator may be, for example, an ester compound. If 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 hydrophilicity and allowing the basic developer to more easily penetrate into the polyamic acid.

[0091] 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.

[0092] The development accelerators may be used alone or in combination of two or more.

[0093] Examples of the ester compound include nitrogen-free ester compounds and nitrogen-containing ester compounds. In terms of heat resistance, nitrogen-free ester compounds are preferred.

[0094] 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. Preferably, nitrogen-free ester compounds that contain an aromatic ring are used.

[0095] Examples of the nitrogen-free ester compound that does not contain an aromatic ring include cyclic ester compounds, such as ε-caprolactone, glycolide, DL-lactide, tetramethylglycolide, delta-octanolactone, DL-mevalonolactone, and gamma-heptanolactone.

[0096] 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.

[0097] Examples of aromatic ring-containing aliphatic carboxylic acid ester compounds include aromatic ring-containing acetate ester compounds, such as (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.

[0098] 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.

[0099] Examples of benzoic acid ester compounds 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 phenylbenzoate (phenyl benzoate). Phenylbenzoate (phenyl benzoate) is preferred.

[0100] Benzoic acid ester compounds also include 4-hydroxybenzoic acids (parabens) represented by the following general formula (9).

[0101] [ka]

[0102] In the general formula (9), R16 is, for example, a hydrocarbon group. It is preferably a hydrocarbon group having 1 to 8 carbon atoms. It is more preferably a hydrocarbon group having 1 to 4 carbon atoms.

[0103] Examples of 4-hydroxybenzoic acid (paraben) include methyl-4-hydroxybenzoate (methylparaben), ethyl-4-hydroxybenzoate (ethylparaben), propyl-4-hydroxybenzoate (propylparaben), isopropyl-4-hydroxybenzoate (isopropylparaben), butyl-4-hydroxybenzoate (butylparaben), isobutyl-4-hydroxybenzoate (isobutylparaben), hexyl-4-hydroxybenzoate (hexylparaben), 2-methylpropyl-4-hydroxybenzoate, 2-ethylhexyl-4-hydroxybenzoate, and benzyl-4-hydroxybenzoate (benzylparaben).Preferably, butylparaben shown in the following formula (10) can be used.

[0104] [ka]

[0105] Examples of phthalate ester compounds include dimethyl phthalate, diethyl phthalate, dipropyl phthalate, diisopropyl phthalate, dibutyl phthalate, diisobutyl phthalate, dihexyl phthalate, diphenyl phthalate, and bis(2-methoxyethyl) phthalate.

[0106] Trimellitate ester compounds include trimethyl trimellitate, tripropyl trimellitate, tributyl trimellitate, and tris(2-ethylhexyl) trimellitate.

[0107] The nitrogen-free ester compound is preferably a benzoic acid ester compound. More preferably, phenyl benzoate (phenyl benzoate) and 4-hydroxybenzoic acids (parabens) are used. Even more preferably, phenyl benzoate (phenyl benzoate) and butylparaben are used. Especially preferably, butylparaben is used.

[0108] Examples of the nitrogen-containing ester compound include imide acrylate compounds.

[0109] Examples of imide acrylate compounds include N-acryloyloxyethylhexahydrophthalimide, N-acryloyloxyethyl-1,2,3,6-tetrahydrophthalimide, and N-acryloyloxyethyl-3,4,5,6-tetrahydrophthalimide, with N-acryloyloxyethylhexahydrophthalimide being preferred.

[0110] The development accelerator is, for example, a benzoic acid ester compound or an imide acrylate compound. Preferably, it is phenyl benzoate (phenyl benzoate), 4-hydroxybenzoic acids, or N-acryloyloxyethylhexahydrophthalimide. More preferably, it is 4-hydroxybenzoic acids (parabens). Even more preferably, it is butylparaben.

[0111] The content of the development accelerator in the photosensitive polyimide precursor composition (solid content) is, for example, 0.5% by mass to 50% by mass, preferably 5.0% by mass to 40% by mass, more preferably 10% by mass to 35% by mass, even more preferably 13% by mass to 30% by mass, and particularly preferably 15% by mass to 25% by mass.

[0112] The content of the development accelerator in the photosensitive polyimide precursor composition (solid content) is, for example, 0.5% by mass or more, preferably 5.0% by mass or more, more preferably 10% by mass or more, even more preferably 13% by mass or more, particularly preferably 15% by mass or more, and for example, 50% by mass or less, preferably 40% by mass or less, more preferably 35% by mass or less, even more preferably 30% by mass or less, particularly preferably 25% by mass or less.

[0113] When the content of the development accelerator in the photosensitive polyimide precursor composition (solid content) is equal to or less than the above upper limit, the photolithography properties can be further improved.

[0114] The amount of the development accelerator to be blended relative to 100 parts by mass of the polyamic acid (solid content) is, for example, 5 parts by mass to 80 parts by mass, preferably 10 parts by mass to 70 parts by mass, more preferably 20 parts by mass to 60 parts by mass, even more preferably 23 parts by mass to 55 parts by mass, and particularly preferably 25 parts by mass to 40 parts by mass.

[0115] The amount of the development accelerator blended relative to 100 parts by mass of the polyamic acid (solid content) is, for example, 5 parts by mass or more, preferably 10 parts by mass or more, more preferably 20 parts by mass or more, even more preferably 23 parts by mass or more, particularly preferably 25 parts by mass or more, and for example, 80 parts by mass or less, preferably 70 parts by mass or less, more preferably 60 parts by mass or less, even more preferably 55 parts by mass or less, particularly preferably 40 parts by mass or less.

[0116] When the blending amount of the development accelerator relative to 100 parts by mass of the polyamic acid (solid content) is equal to or less than the upper limit, compatibility is excellent and development contrast can be improved, that is, photolithography properties can be improved.

[0117] The amount of the development accelerator blended relative to 100 parts by mass of the photosensitizer is, for example, 50 parts by mass to 1,000 parts by mass, preferably 100 parts by mass to 800 parts by mass, more preferably 150 parts by mass to 600 parts by mass, even more preferably 200 parts by mass to 500 parts by mass, and particularly preferably 250 parts by mass to 350 parts by mass.

[0118] The amount of the development accelerator blended relative to 100 parts by mass of the photosensitizer is, for example, 50 parts by mass or more, preferably 100 parts by mass or more, more preferably 150 parts by mass or more, even more preferably 200 parts by mass or more, particularly preferably 250 parts by mass or more, and for example, 1000 parts by mass or less, preferably 800 parts by mass or less, more preferably 600 parts by mass or less, even more preferably 500 parts by mass or less, particularly preferably 350 parts by mass or less.

[0119] <Other ingredients> The photosensitive polyimide precursor composition may contain other components, but preferably does not contain other components, such as a photosensitizer.

[0120] Photosensitizers include, for example, 3,3'-carbonylbis(7-N,N-dimethoxy)coumarin, 3-benzoylcoumarin, 3-benzoyl-7-N,N-methoxycoumarin, and benzalacetophenone.

[0121] 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.

[0122] <Method for preparing photosensitive polyimide precursor composition> The photosensitive polyimide precursor composition can be prepared, for example, by mixing a polyamic acid, a photosensitizer, and optionally added development accelerators and / or other components. The photosensitive polyimide precursor composition can be prepared as a diluted solution (varnish) of the photosensitive polyimide precursor composition by mixing a solution of the polyamic acid, a photosensitizer, and optionally added development accelerators and / or other components in an organic solvent. Specifically, the diluted solution (varnish) of the photosensitive polyimide precursor composition can be prepared by blending a photosensitizer and optionally added development accelerators and / or other components with a polyamic acid solution obtained by reacting a tetracarboxylic dianhydride with a diamine component in an organic solvent.

[0123] Examples of the organic solvent include aprotic polar solvents, such as N-methyl-2-pyrrolidone, N,N-dimethylacetamide, dimethyl sulfoxide, dimethylformamide, and hexamethylphosphoramide.

[0124] The amount of the organic solvent blended relative to 100 parts by mass of polyamic acid (solid content) is, for example, 150 parts by mass to 2000 parts by mass.

[0125] The content of polyamic acid (solid content) in the diluted solution (varnish) of the photosensitive polyimide precursor composition is, from the viewpoint of ensuring a good viscosity of the photosensitive polyimide precursor composition, for example, 5% by mass or more, preferably 7.5% by mass or more, more preferably 10% by mass or more, and for example, 20% by mass or less, preferably 17% by mass or less, more preferably 15% by mass or less.

[0126] The content of the photosensitizer in the diluted solution (varnish) of the photosensitive polyimide precursor composition is, for example, 0.01 mass% or more, preferably 0.05 mass% or more, more preferably 0.10 mass% or more, and for example, 10 mass% or less, preferably 5.0 mass% or less, more preferably 3.0 mass% or less.

[0127] When the content of the photosensitizer in the diluted solution (varnish) of the photosensitive 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 photosensitive polyimide precursor composition can be promoted, and the solubility of the exposed area in the developer can be reduced. When the content of the photosensitizer in the diluted solution (varnish) of the photosensitive polyimide precursor composition is equal to or less than the upper limit, the reduction in the thickness of the polyimide resin pattern can be suppressed during the heating step.

[0128] The content of the development accelerator in the diluted solution (varnish) of the photosensitive polyimide precursor composition is, for example, 0.05% by mass or more, preferably 0.10% by mass or more, more preferably 0.30% by mass or more, and for example, 12% by mass or less, preferably 10% by mass or less, more preferably 8.0% by mass or less.

[0129] When the content of the development accelerator in the diluted solution (varnish) of the photosensitive polyimide precursor composition is equal to or greater than the lower limit, excessive imidization of the polyamic acid can be suppressed. When the content of the development accelerator in the diluted solution (varnish) of the photosensitive polyimide precursor composition is equal to or less than the upper limit, sufficient compatibility can be ensured, and development contrast can be improved.

[0130] The photosensitive polyimide precursor composition (or varnish) forms a polyimide resin by heat curing.

[0131] 2. Polyimide resin The polyimide resin is a cured product of the photosensitive polyimide precursor composition. Specifically, the polyimide resin can be formed by heating and curing the photosensitive polyimide precursor composition (or varnish). The heating temperature is, for example, 300°C to 450°C.

[0132] The polyimide resin is used, for example, as an insulating layer or a covering layer of a printed circuit board, which will be described later.

[0133] The coefficient of thermal expansion under humidity (CHE) of the polyimide resin is, for example, 15 or less, preferably 14 or less, more preferably 13 or less, and for example, 7 or more.

[0134] When the coefficient of thermal expansion (CHE) of a polyimide resin is equal to or less than the upper limit, the polyimide resin has low water absorption, which in turn suppresses dimensional changes due to moisture (humidity) in the air and improves reliability when used in printed circuit boards and electronic devices.

[0135] The coefficient of thermal expansion (CHE) of a polyimide resin can be measured by the method described in the examples below.

[0136] 3. Wiring circuit board The printed circuit board includes, for example, a base material, an insulating layer, a wiring layer, and a covering layer in that order in the thickness direction. The covering layer is disposed so as to cover the wiring layer. At least one layer selected from the group consisting of the insulating layer and the covering layer contains a polyimide resin that is a cured product of the photosensitive polyimide precursor composition.

[0137] The shape of the substrate may be, for example, a film (including a sheet) having a predetermined thickness, or a plate.

[0138] Examples of the substrate include a silicon wafer, a ceramic sheet (ceramic plate), and a metal sheet (metal plate). Examples of the metal include aluminum, stainless steel, and copper.

[0139] The thickness of the substrate is, for example, 5 μm to 300 μm, preferably 10 μm to 200 μm, and more preferably 15 μm to 150 μm.

[0140] Examples of the material for the insulating layer include a polyimide resin that is a cured product of the above-mentioned photosensitive polyimide precursor composition. When the material for the covering layer described below is a polyimide resin that is a cured product of the above-mentioned photosensitive polyimide precursor composition, the material for the insulating layer may be a known material that is usually used for wiring circuit boards.

[0141] The thickness of the insulating layer is, for example, 1 μm to 50 μm, or preferably 5 μm to 30 μm.

[0142] Examples of materials for the wiring layer include metals. Preferably, chromium and copper are used. More preferably, copper is used. The materials for the wiring layer may be used alone or in combination of two or more. Preferably, chromium and copper are used in combination.

[0143] 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.

[0144] Examples of the material for the covering layer include a polyimide resin that is a cured product of the photosensitive polyimide precursor composition. When the material for the insulating layer is a polyimide resin that is a cured product of the photosensitive polyimide precursor composition, the material for the covering layer may be a known material that is commonly used for wiring circuit boards.

[0145] The thickness of the coating layer is, for example, 1 μm to 50 μm, or preferably 5 μm to 30 μm.

[0146] Next, as one embodiment of a wiring circuit board using a photosensitive polyimide precursor composition, a method for forming an insulating layer of a wiring circuit board from a photosensitive polyimide precursor composition will be described with reference to FIGS. 1A to 1E.

[0147] First, as shown in FIG. 1A, a diluted solution (varnish) of the photosensitive polyimide precursor composition is applied onto a substrate S to form a coating film 10A (coating step).

[0148] Examples of the application method include spin coating and screen printing.

[0149] Next, as shown in FIG. 1B, the coating film 10A is dried by heating to form a dried coating film 10B on the substrate S (drying step).

[0150] The drying temperature is, for example, 100° C. to 200° C. The drying time is, for example, 1 minute to 15 minutes. The thickness of the dried coating film 10B is, for example, 1 μm to 50 μm.

[0151] Next, as shown in FIG. 1C, the dried coating film 10B is irradiated with ultraviolet light through a photomask M (exposure step). The photomask M has openings Ma corresponding to the pattern shape of the insulating layer 10C. In this step, exposed portions 11 and unexposed portions 12 are generated in the dried coating film 10B. After the ultraviolet light irradiation, the dried coating film 10B may be preheated.

[0152] The wavelength of the irradiated ultraviolet light is, for example, 300 nm to 500 nm. The cumulative irradiation amount of the ultraviolet light is, for example, 100 mJ / cm 2 2 ~1000mJ / cm 2 is.

[0153] The preheating temperature is, for example, 100° C. to 300° C. The preheating time is, for example, 1 minute to 30 minutes.

[0154] 1D, the dried coating film 10B is developed (developing step). Specifically, the unexposed portions 12 of the dried coating film 10B are dissolved and removed by the developer.

[0155] The developer may be, for example, a basic developer. The basic developer may be, for example, an inorganic alkaline solution or an organic alkaline solution. The inorganic alkaline solution may be, for example, an aqueous solution of sodium hydroxide or an aqueous solution of potassium hydroxide. The organic alkaline solution may be, for example, an aqueous solution of tetramethylammonium hydroxide (TMAH) or a TMAH / equinene (a mixed solvent mainly composed of ethanol) solution. Preferably, a TMAH / equinene solution is used.

[0156] Examples of the developing method include a dipping method, a spray method, and a puddle method.

[0157] Next, as shown in Fig. 1E, the exposed portions 11 of the dried coating film 10B on the substrate S are heated. This hardens the exposed portions 11 of the dried coating film 10B, forming a polyimide resin and forming a pattern of the insulating layer 10C (heating step).

[0158] The heating temperature is, for example, 300° C. to 450° C. The heating time is, for example, 1 hour to 10 hours.

[0159] In this manner, an insulating layer 10C made of a polyimide layer having a predetermined pattern is formed on the substrate S.

[0160] Although not shown, a wiring layer is formed by a semi-additive method on the insulating layer 10C formed on the substrate S, and then a covering layer is formed to cover the wiring layer, thereby manufacturing a wired circuit board.

[0161] Specifically, a metal wiring layer material is deposited on the insulating layer 10C as a base by sputter deposition to form a metal layer. Next, a plating resist with a reverse pattern to the desired wiring pattern is formed using a dry film resist. Then, a wiring layer with the desired wiring pattern is formed by copper plating in the areas of the metal layer where the plating resist is not formed. The plating resist is then removed by chemical etching, and the metal layer in the areas where the plating resist was formed is also removed by chemical etching.

[0162] Next, a coating layer material (for example, a diluted solution (varnish) of the above-mentioned photosensitive polyimide precursor composition) is applied onto the wiring layer to form a coating layer film, and then cured in the same manner as the above-mentioned insulating layer, thereby forming the coating layer.

[0163] In this manner, a wired circuit board can be produced. An example of such a wired circuit board is a suspension board with a circuit for a hard disk drive.

[0164] The printed circuit board may have a metal underlayer (for example, a nickel layer or a chromium layer) between the wiring layer and the covering layer, which improves adhesion between the wiring layer and the covering layer.

[0165] 4.Electronic equipment The electronic device includes the above-described printed circuit board.

[0166] Examples of electronic devices include notebook personal computers and smartphones.

[0167] (Action and effect) The photosensitive polyimide precursor composition of the present invention contains a polyamic acid and a photosensitizer, and the polyamic acid is a reaction product of an acid dianhydride component containing biphenyltetracarboxylic dianhydride and a diamine component containing p-phenylenediamine and a fluorine-free biphenyl-type diamine. Therefore, the photosensitive polyimide precursor composition has low water absorption while reducing the environmental impact.

[0168] The polyimide resin of the present invention is formed from the photosensitive polyimide precursor composition of the present invention, and therefore has low water absorption while reducing the environmental load.

[0169] The wired circuit board of the present invention contains the polyimide resin of the present invention. Therefore, the environmental impact can be reduced. Furthermore, the low water absorption of the polyimide resin suppresses dimensional changes due to moisture, thereby improving reliability.

[0170] The electronic device of the present invention includes the wired circuit board of the present invention. Therefore, the environmental impact can be reduced. Furthermore, the low water absorption suppresses dimensional changes due to moisture, and reliability is improved. [Example]

[0171] 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 property values, parameters, etc. used in the following description can be substituted 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 property values, parameters, etc. described in the "Mode for Carrying Out the Invention" above.

[0172] <Ingredient details> The trade names and abbreviations of the components used in each example and each comparative example are described in detail below.

[0173] BPDA: 3,3',4,4'-biphenyltetracarboxylic dianhydride PDA: p-phenylenediamine m-TD: m-tolidine TFMB: 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl ODA: 4,4'-diaminodiphenyl ether NMP: N-methyl-2-pyrrolidone NKS-4: 1-ethyl-3,5-dimethoxycarbonyl-4-(2-nitrophenyl)-4-hydropyridine DMNZP: N-{[(4,5-dimethoxy-2-nitrobenzyl)oxy]carbonyl}2,6-dimethylpiperidine BP: Butylparaben Aronix: N-acryloyloxyethylhexahydrophthalimide, manufactured by Toagosei Co., Ltd. PB: Phenyl benzoate TMAH: tetramethylammonium hydroxide Equinene: A mixed solvent with ethanol as the main ingredient

[0174] <Preparation of Photosensitive Polyimide Precursor Composition> Example 1 First, polyamic acid (A) was synthesized. Specifically, in a 300 mL four-neck flask, a solution containing 29.41 g (100 mmol) of BPDA, 7.57 g (70 mmol) of PDA, 6.37 g (30 mmol) of m-TD, and 266 g of NMP was stirred under heating (80°C) (synthesis of polyamic acid (A)). This resulted in an NMP solution containing polyamic acid (A). The synthesized polyamic acid (A) contained the first structural unit described above. The proportion of the first structural unit in this polyamic acid (A) was 70 mol%.

[0175] Next, the NMP solution containing polyamic acid (A), NKS-4 (photosensitizer), and BP (development accelerator) were mixed to prepare a varnish of a photosensitive polyimide precursor composition. The photosensitive polyimide precursor composition was prepared by mixing the polyamic acid (A) (solid content), NKS-4 (photosensitizer), and BP (development accelerator) in a composition ratio (mass ratio) of 62:6:32. This resulted in a solution (varnish) of the photosensitive polyimide precursor composition of Example 1.

[0176] Examples 2 to 7 As shown in Table 1, the photosensitive polyimide precursor compositions of Examples 2 to 7 were prepared in the same manner as the photosensitive polyimide precursor composition of Example 1, except that at least one selected from the group consisting of the type of photosensitizer, the type of development accelerator, and the composition ratio was changed.

[0177] Example 8 The photosensitive polyimide precursor composition of Example 8 was prepared in the same manner as the photosensitive polyimide precursor composition of Example 1, except that polyamic acid (A) was changed to polyamic acid (B) as shown in Table 1. The preparation of polyamic acid (B) is described below.

[0178] In a 300 mL four-neck flask, a solution containing 29.42 g (100 mmol) of BPDA, 5.41 g (50 mmol) of PDA, 10.62 g (50 mmol) of m-TD, and 279 g of NMP was stirred under heating (80°C) (synthesis of polyamic acid (B)). This resulted in an NMP solution containing polyamic acid (B). The synthesized polyamic acid (B) contains the first structural unit described above. The proportion of the first structural unit in this polyamic acid (B) was 50 mol%.

[0179] Comparative Example 1 A photosensitive polyimide precursor composition of Comparative Example 1 was prepared in the same manner as the photosensitive polyimide precursor composition of Example 1, except that polyamic acid (A) was changed to polyamic acid (C) as shown in Table 2. The preparation of polyamic acid (C) is described below.

[0180] In a 300 mL four-neck flask, a solution containing 29.42 g (100 mmol) of BPDA, 6.49 g (60 mmol) of PDA, 12.81 g (40 mmol) of TFMB, and 299 g of NMP was stirred at room temperature (25°C) (synthesis of polyamic acid (C)). This resulted in an NMP solution containing polyamic acid (C). The synthesized polyamic acid (C) contained the first structural unit described above. The proportion of the first structural unit in this polyamic acid (C) was 60 mol%.

[0181] Comparative Examples 2 and 3 Photosensitive polyimide precursor compositions of Comparative Examples 2 and 3 were prepared in the same manner as the photosensitive polyimide precursor composition of Example 1, except that polyamic acid (A) was changed to polyamic acid (D) and at least one selected from the group consisting of the type and composition ratio of the development accelerator was changed as shown in Table 2. The preparation of polyamic acid (D) is described below.

[0182] In a 300 mL four-neck flask, a solution containing 29.42 g (100 mmol) of BPDA, 9.19 g (85 mmol) of PDA, 3.00 g (15 mmol) of ODA, and 256 g of NMP was stirred under heating (75°C) (synthesis of polyamic acid (D)). This resulted in an NMP solution containing polyamic acid (D). The synthesized polyamic acid (D) contained the first structural unit described above. The proportion of the first structural unit in this polyamic acid (D) was 85 mol%.

[0183] <Evaluation> [Environmental load] The environmental impact of the photosensitive polyimide precursor compositions of each Example and Comparative Example was evaluated according to the following criteria. The results are shown in Tables 1 and 2. {standard} A: The photosensitive polyimide precursor composition does not contain fluorine atoms. B: The photosensitive polyimide precursor composition contains fluorine atoms.

[0184] [Hygrothermal expansion coefficient (CHE)] The solution (varnish) of the photosensitive polyimide precursor composition of each Example and Comparative Example was spin-coated onto a SUS foil (thickness: 20 μm) as a substrate using a spin coater (product name: Opticoat MS-B200, manufactured by Mikasa Co., Ltd.) at 1100 rpm for 30 seconds, and then heated and dried at 130°C for 5 minutes in an explosion-proof dryer (product name: SPHH-201, manufactured by Espec Co., Ltd.) to form a coating film (thickness: 28 μm) made of the photosensitive polyimide precursor composition. Next, this coating film was irradiated with ultraviolet light (wavelength: 365 nm, 400 mJ / cm) using a simple exposure device (product name: UV-2001M-ND, manufactured by CES Co., Ltd.). 2 ) and heated at 185°C for 5 minutes using a blower dryer (product name: DRM320DA, manufactured by Advantec Co., Ltd.). Furthermore, using a laboratory curing oven (product name: Infrared Heating System E42327, manufactured by Noritake Co., Ltd.), the mixture was heated at a target temperature of 360°C to harden (imidize), thereby producing a 20 μm-thick film-like polyimide resin on the substrate. The substrate was then removed to obtain a polyimide resin film.

[0185] The resulting polyimide resin film (thickness: 20 μm) was cut into a 5 mm wide x 1.5 mm long sample for measuring the coefficient of thermal expansion (CHE). Each sample was attached to the chuck of a humidity-controlled TMA (product name: HC-TMA400SA, manufactured by Bruker). Humidification was performed at a constant temperature of 30°C, with a 20 g load applied, using a tensile method to raise the humidity from 5% RH to 75% RH. The coefficient of thermal expansion (CHE) of the polyimide resin film was determined by measuring the maximum elongation 5 hours after reaching 75% RH. The results are shown in Tables 1 and 2.

[0186] [Photolithography] The solution (varnish) of the photosensitive polyimide precursor composition of each Example and Comparative Example was spin-coated onto SUS foil (stainless steel foil) and heated at 130°C for 5 minutes to obtain a film with a thickness of approximately 28 μm. Half of this film was covered with SUS foil and exposed to an exposure dose of 400 mJ / cm2 using an exposure machine. 2After exposure at 1000 K, the film was heated at 185°C for 5 minutes to obtain a two-part patterned film with a thickness of approximately 20 μm. The film was then developed by several 30-second dip developments in a TMAH / equine solution and rinsed with deionized water. The thickness of the exposed portion after development was measured using a linear gauge. The reduction rate of the thickness of the exposed portion after development relative to the thickness of the exposed portion before development (approximately 20 μm) was calculated using the following formula. In the formula, the part indicating the change in thickness of the exposed portion (thickness of the exposed portion after development - thickness of the exposed portion before development) is a negative value. However, since the formula indicates the reduction rate of the thickness of the exposed portion, a "-" was added to correct the difference. The calculated reduction rate of the thickness of the exposed portion was evaluated according to the following criteria. The results are shown in Tables 1 and 2. In each example and comparative example, the unexposed portion was removed by development. Reduction rate of thickness of exposed part (%) = - (thickness of exposed part after development - thickness of exposed part before development) / thickness of exposed part before development x 100 {standard} A: The reduction in thickness of the exposed area is less than 10% B: The reduction in thickness of the exposed area is 10% or more but less than 50% C: The thickness of the exposed area is reduced by 50% or more.

[0187] [Table 1]

[0188] [Table 2] [Explanation of symbols]

[0189] S base material 10A coating 10B Dry coating film 10C Insulation layer 11 Exposure area 12 Unexposed area

Claims

1. A photosensitive polyimide precursor composition comprising a polyamic acid and a photosensitizer, The polyamic acid is a reaction product of an acid dianhydride component and a diamine component, the acid dianhydride component includes biphenyltetracarboxylic dianhydride, The diamine component comprises p-phenylenediamine and a fluorine-free biphenyl-type diamine.

2. 2. The photosensitive polyimide precursor composition according to claim 1, wherein the photosensitizer comprises a pyridine-based photosensitizer.

3. 2. The photosensitive polyimide precursor composition according to claim 1, wherein a content of the photosensitizer in the photosensitive polyimide precursor composition (solid content) is 10.0 mass % or less.

4. The photosensitive polyimide precursor composition of claim 1 , further comprising a development accelerator.

5. 5. The photosensitive polyimide precursor composition according to claim 4, wherein the development accelerator comprises a benzoate compound.

6. 6. The photosensitive polyimide precursor composition according to claim 5, wherein the benzoic acid ester compound comprises a paraben.

7. 7. The photosensitive polyimide precursor composition according to claim 6, wherein the parabens comprise butylparaben.

8. 5. The photosensitive polyimide precursor composition according to claim 4, wherein a content of the development accelerator in the photosensitive polyimide precursor composition (solid content) is 35.0 mass % or less.

9. 2. The photosensitive polyimide precursor composition according to claim 1, wherein the content of the fluorine-free biphenyl-type diamine in the diamine component is 20 mol % or more and 60 mol % or less.

10. A polyimide resin which is a cured product of the photosensitive polyimide precursor composition according to any one of claims 1 to 9.

11. A printed circuit board comprising the polyimide resin according to claim 10.

12. An electronic device comprising the printed circuit board according to claim 11.

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