JP2007086763A - Photosensitive resin composition and circuit board using same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide: a photosensitive polyimide resin composition containing no acid generator and capable of performing heat treatment at a lowered temperature, which is difficult in the case of a conventional polyimide resin; an alkali developable photosensitive cover lay; and a circuit board using the same. <P>SOLUTION: The photosensitive resin composition developable with an alkaline aqueous solution contains a soluble polyimide having a carboxyl group in a molecule and a photobase generator capable of generating an amino group upon photoirradiation. The circuit board has the photosensitive cover lay using the photosensitive resin composition. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a novel photosensitive resin composition using a photobase generator and a circuit board using the same.

  Polyimide resins are applied in various fields based on excellent properties such as high insulation, heat and cold resistance, and high strength. In recent years, polyimides have been used as base materials and coverlays in flexible printed wiring boards (hereinafter abbreviated as FPCs) that are remarkably elongated. FPCs are required to be finer in line with the recent advancement and density of IC mounting technology, and high workability is also required for coverlays using polyimide.

  In manufacturing the FPC, the polyimide base material is mechanically punched, and the alignment is performed for bonding. Therefore, there is a problem that the alignment accuracy cannot be increased. In order to solve this problem, a photosensitive film based on a solder resist film using an acrylate resin or an epoxy resin has been studied. However, in terms of physical properties such as flexibility, it was not as good as polyimide (for example, patents). Literatures 1-3).

  In order to realize further miniaturization of wiring, a photosensitive composition capable of alkali development has been developed in recent years. For example, there is a proposal of a photosensitive resin using a photosensitive polyimide precursor and a nitrobenzyl carbamate type photobase generator (for example, Patent Document 4). These proposals utilize the solubility difference between the carboxyl group in the polymer in the unirradiated part and the salt formed by the base generated by light irradiation in the light irradiated part and the carboxyl group in the polymer, It was difficult to take a difference in solubility or a difference in dissolution rate between the light-irradiated part and the non-irradiated part during alkali development. Also, since a polyimide precursor is used, the polyimide precursor in the unirradiated part may react with the polyimide during heating, which is also the difference in solubility or dissolution rate between the light irradiated part and the unirradiated part during alkali development. It was difficult to take. Moreover, since it is necessary to make a polyimide precursor react with a polyimide after image development, it was necessary to perform the heat processing of 200 to 350 degreeC or more high temperature.

Moreover, as a photosensitive polyimide, for example, there is a proposal of a negative type photosensitive polyimide using a photo radical generator, but it is necessary to polymerize an acrylate compound coexisting with the polyimide. In this case, heat treatment at a high temperature of 180 ° C. or higher is performed (for example, Patent Document 5). In addition, there are proposals of positive type photosensitive polyimide using a photoacid generator (for example, Patent Document 6). However, in these, the acid generator remains in the remaining film, and the stability of the formed polyimide film Is concerned. For this reason, if necessary, heat treatment may be performed at a high temperature of about 300 ° C. after development to thermally decompose the acid generator in the remaining film (for example, Patent Document 7).
JP-A-56-6498 JP-A 61-243896 JP-A-6-332171 Japanese Patent No. 3363580 International Publication WO2002 / 023276 International Publication No. WO2000 / 073853 JP 2005-134742 A

  SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and includes a photosensitive polyimide resin composition that does not contain an acid generator and that can be heat-treated at low temperatures and a cover that can be developed with an alkali, which has been difficult with conventional polyimide resins. An object is to provide a ray and realize a circuit board using the same.

（式中αは４価の有機基であり、βは少なくとも１以上のカルボキシル基を有する２価の有機基であり、ａは４価の有機基であり、ｂは２価の有機基である。ｘは１以上の整数を表し、ｙは０以上の整数を表す） The photosensitive resin composition of the present invention contains a soluble polyimide (A) represented by the formula (1) and a photobase generator (B) capable of generating an amino group by light irradiation. .

(Wherein α is a tetravalent organic group, β is a divalent organic group having at least one carboxyl group, a is a tetravalent organic group, and b is a divalent organic group. X represents an integer of 1 or more, and y represents an integer of 0 or more)

  In the photosensitive resin composition of the present invention, a negative photosensitive resin that can be developed with an aqueous alkali solution by causing a difference in solubility and / or a difference in dissolution rate between an irradiated part and an unirradiated part by light irradiation and / or heating. A composition is preferred.

  In the photosensitive resin composition of the present invention, the photobase generator (B) is preferably a photobase generator capable of generating 1 to 4 amino groups from one molecule by light irradiation.

（式中有機基Ｄは１価以上４価以下の有機基であり、Ｒ¹は２価の有機基、Ｒ²、Ｒ³はそれぞれ１価の有機基を示し、Ｒ²、Ｒ³の少なくとも一つは芳香族基を示す。ｍは０又は１であり、ｍが０のとき、前記Ｄの有機基は芳香族基でない。ｎは１以上４以下の整数であり、複数個のＲ¹、Ｒ²、Ｒ³はそれぞれ同一でも異なっていても良い。） In the photosensitive resin composition of this invention, it is preferable that the said photobase generator (B) is represented by Formula (2).

(In the formula, the organic group D is a monovalent to tetravalent organic group, R ¹ is a divalent organic group, R ² and R ³ are each a monovalent organic group, and at least R ² and R ³ One represents an aromatic group, m is 0 or 1, and when m is 0, the organic group of D is not an aromatic group, n is an integer of 1 to 4, and a plurality of R ¹ , R ² and R ³ may be the same or different.

  In the photosensitive resin composition of the present invention, the divalent organic group represented by b in the formula (1) is preferably a divalent organic group having a siloxane skeleton.

（式中のα、β、ａ、ｂ、ｘ、ｙは式（１）と同じである。） In the photosensitive resin composition of the present invention, the soluble polyimide (A) is a functional group that can be crosslinked only by light irradiation or by light irradiation and heating, or the presence of an amine derived from the photobase generator (B). It may have a terminal structure W having a functional group that can be crosslinked only by light irradiation or by light irradiation and heating, and is preferably represented by the formula (3).

(Α, β, a, b, x, and y in the formula are the same as those in the formula (1).)

  In the photosensitive resin composition of this invention, it is preferable that the said photosensitive resin composition contains a photosensitizer (C) further.

  In the photosensitive resin composition of the present invention, the photosensitive resin composition preferably further contains an amidation catalyst (D).

  The method for producing a circuit board of the present invention includes a step of forming a resin composition layer on a substrate having at least wiring using the photosensitive resin composition, and a step of performing pattern exposure on the resin composition layer. And a step of developing the resin composition layer after the pattern exposure using an alkaline aqueous solution.

  The circuit board of the present invention is obtained by the above method. The circuit board of the present invention is composed of a base material having wiring and a substance formed on the base material so as to cover the wiring, and obtained by exposing and developing the photosensitive resin composition. And a coverlay.

  The film of this invention was comprised with the said photosensitive resin composition, It is characterized by the above-mentioned. The laminated film of the present invention comprises a carrier film and the film provided on the carrier film. In this case, it is preferable to provide a cover film formed on the film.

  Since the photosensitive resin composition of the present invention contains the soluble polyimide (A) represented by the above formula (1) and the photobase generator (B) capable of generating an amino group by light irradiation, It is possible to provide a photosensitive polyimide resin composition that does not contain an acid generator and is capable of lowering the temperature of heat treatment, which has been difficult with a polyimide resin. When the photosensitive resin composition of the present invention is used, a cover lay capable of alkali development can be provided, and a circuit board can be produced using the cover lay.

  The inventors of the present invention realized an alkali-soluble photosensitive polyimide resin composition by introducing a carboxyl group into polyimide and combining the polyimide with a photobase generator, and achieved photolithography by alkali development.

  That is, the gist of the present invention is to reduce the solubility difference or dissolution rate difference by combining the alkali-soluble polyimide resin and the photobase generator and introducing a function capable of forming a crosslinked structure in the light irradiation part of the photosensitive resin. It is to provide a novel photosensitive resin composition that can be alkali-developed satisfactorily by low-temperature heat treatment and a photosensitive coverlay that can be alkali-developed, and to provide a circuit board using the same.

Hereinafter, embodiments of the present invention will be described in detail.
A soluble polyimide is a polyimide soluble in an organic solvent. Examples of the organic solvent include N-methyl-2-pyrrolidone, N, N-dimethylacetamide, N, N-dimethylformamide, dimethylsulfoxide, and γ-butyrolactone. The term “soluble” in the present invention specifically means that it dissolves in N-methyl-2-pyrrolidone or γ-butyrolactone at least 5% by weight, preferably 10% by weight or more.

（式中αは４価の有機基であり、βは少なくとも１以上のカルボキシル基を有する２価の有機基であり、ａは４価の有機基であり、ｂは２価の有機基である。ｘは１以上の整数を表し、ｙは０以上の整数を表す） The soluble polyimide (A) represented by the formula (1) of the present invention is specifically a polyimide having a carboxyl group.

(Wherein α is a tetravalent organic group, β is a divalent organic group having at least one carboxyl group, a is a tetravalent organic group, and b is a divalent organic group. X represents an integer of 1 or more, and y represents an integer of 0 or more)

First, α will be described. In formula (1), α is a tetravalent organic group. Polyimide can be synthesized via polyamic acid using tetracarboxylic dianhydride and diamine as raw materials. α can be introduced into the polyimide by, for example, tetracarboxylic dianhydride represented by the formula (4).

As such a tetracarboxylic dianhydride, an aromatic tetracarboxylic dianhydride, an aliphatic tetracarboxylic dianhydride, or the like can be used. For example, aromatic tetracarboxylic dianhydride includes those listed in Formula (5). For example, aliphatic tetracarboxylic dianhydrides include those listed in Formula (6). The introduction site of α in the compounds represented by formulas (5) and (6) corresponds to the position of α in formula (1). These tetracarboxylic dianhydrides can be used alone or in combination.

  Such a tetracarboxylic dianhydride is not particularly limited, but from the viewpoint of imparting solvent solubility to the polyimide, a tetracarboxylic dianhydride or an aliphatic tetracarboxylic dianhydride having a hexafluoroisopropylidene group or Tetracarboxylic dianhydrides having no symmetry are preferred. Specifically, for example, 4,4 ′-(2,2-hexafluoroisopropylidene) diphthalic dianhydride (6FDA), 1,5-cyclooctadiene-1,2,5,6-tetracarboxylic acid Dianhydride (COEDA), 5- (2,5-dioxotetrahydro-3-furanyl) -3-methyl 3-cyclohexene-1,2-dicarboxylic anhydride (MCTC, Epiclon B-4400), 5-carboxymethyl Bicyclo [2.2.1] heptane-2,3,6-tricarboxylic acid-2,3: 5,6-dianhydride (NDA), 1-carboxymethyl-2,3,5-cyclopentanetricarboxylic acid- 2,6: 3,5-dianhydride, bicyclo [2.2.2] oct-7-ene-2,3,5,6-tetracarboxylic dianhydride, 4- (2,5-dioxo Tetrahydrofuran 3-yl) -1,2,3,4-tetrahydronaphthalene-1,2-dicarboxylic anhydride (RIKACID TDA-100), and the like. These tetracarboxylic dianhydrides can be used alone or in combination.

このようなジアミンとしては、カルボキシル基を有するジアミンを用いることができる。例えば式（８）に示すものなどである。式（８）に示す化合物のβの導入箇所は式（１）中のβの位置に対応する。これらカルボキシル基を有するジアミンは単独又は組み合わせて用いることができる。

Next, β will be described. β is a divalent organic group having at least one carboxyl group, and can be introduced by a diamine represented by the formula (7) when a polyimide is synthesized.

As such a diamine, a diamine having a carboxyl group can be used. For example, it is shown in Formula (8). The introduction site of β in the compound represented by the formula (8) corresponds to the position of β in the formula (1). These diamines having a carboxyl group can be used alone or in combination.

Next, a will be described. In the formula, a is a tetravalent organic group. a can be introduced from, for example, a tetracarboxylic dianhydride represented by the formula (9).

  A of the compound represented by the formula (9) corresponds to a in the formula (1). As the tetracarboxylic dianhydride represented by the formula (9), tetracarboxylic dianhydrides represented by the formulas (5) and (6) can be used. Such a tetracarboxylic dianhydride is not particularly limited, but from the viewpoint of imparting solvent solubility to the polyimide, a tetracarboxylic dianhydride or an aliphatic tetracarboxylic dianhydride having a hexafluoroisopropylidene group or Tetracarboxylic dianhydrides having no symmetry are preferred. Specifically, for example, 4,4 ′-(2,2-hexafluoroisopropylidene) diphthalic dianhydride, 1,5-cyclooctadiene-1,2,5,6-tetracarboxylic dianhydride (COEDA), 5- (2,5-dioxotetrahydro-3-furanyl) -3-methyl 3-cyclohexene-1,2-dicarboxylic anhydride (MCTC, Epiclon B-4400), 5-carboxymethylbicyclo [2 2.1] Heptane-2,3,6-tricarboxylic acid-2,3: 5,6-dianhydride (NDA), 1-carboxymethyl-2,3,5-cyclopentanetricarboxylic acid-2,6 : 3,5-dianhydride, bicyclo [2.2.1] oct-7-ene-2,3,5,6-tetracarboxylic dianhydride, 4- (2,5-dioxotetrahydrofuran-3 -Ile) 1,2,3,4-tetrahydronaphthalene-1,2-dicarboxylic acid anhydride (RIKACID TDA-100), and the like. These tetracarboxylic dianhydrides can be used alone or in combination.

Next, b will be described. b is a divalent organic group and can be introduced by a diamine represented by the formula (10) when a polyimide is synthesized. The divalent organic group represented by b is preferably a divalent organic group having a siloxane skeleton in consideration of physical properties such as flexibility, elongation, and bending resistance when formed into a film.

  B in the formula (10) corresponds to b in the formula (1). Examples of the diamine represented by the formula (10) include aromatic diamines, aliphatic diamines, alicyclic amines, diaminosilane compounds, and the like. Aromatic diamines include 4,4′-diaminodiphenyl ether, 3,4′-diaminodiphenyl ether, bis (4-aminophenoxy) 1,4-benzene, bis (3-aminophenoxy) 1,4-benzene, bis ( 3-aminophenoxy) 1,3-benzene, 2,2-bis (4-aminophenyl) propane, 1,1,1,3,3,3-hexafluoro-2-bis (4-aminophenyl) propane, 4,4′-diaminodiphenylmethane, bis (4-aminophenoxy) 4,4′-diphenyl, 2,2-bis {(4-aminophenoxy) phenyl} propane, 2,2-bis {(4-aminophenoxy) Phenyl} hexafluoropropane, 1,3-diaminobenzene, 1,4-diaminobenzene, 2,4-diaminotoluene, 3,3′- Methyl-4,4′-diaminobiphenyl, 2,2′-bis (trifluoromethyl) benzidine, bis (4-aminophenoxy) -1,3- (2,2-dimethyl) propane, 1,2-bis [ 2- (4-aminophenoxy) ethoxy] ethane and 1, n-bis (4-aminophenoxy) alkane.

  As the aromatic diamine, those introduced with a carbonyl group, a nitro group, a methoxy group, a sulfone group, a sulfide group, an anthracene group or a fluorene group can also be used. These can be used for adjusting the absorbance and adjusting the photosensitization effect. For example, 3,3′-dimethyl-4,4′-diamino-biphenylsulfone, 3,3′-dimethoxy-4,4′-diamino-biphenylsulfone, 4,4′-bis (4-aminophenyl) sulfide, 9,9-bis (4-aminophenyl) fluorene, 1,4-diamino-2-nitrobenzene, 1,5-diamino-2-nitrobenzene, 3-nitro-4,4′-diaminobiphenyl, 3,3′- Dinitro-4,4′-diaminobiphenyl, 2,4-diaminoacetophenone, 2,4-diaminobenzophenone, 4,4′-diaminobenzophenone, 4,4′-diaminobenzanilide, 2-amino-4′-aminobenzophenone 2-amino-5-aminofluorenone, 9,9-bis (4-aminophenyl) fluorene, 3,3′-diaminodi Phenylsulfone, 4,4′-diaminodiphenylsulfone, bis- {4- (3-aminophenoxy) biphenyl} sulfone, bis- {4- (4-aminophenoxy) biphenyl} sulfone, bis {4- (4-amino) Phenoxy) phenyl} sulfone, bis {4- (3-aminophenoxy) phenyl} sulfone, o-tolidine sulfone, 4,4′-diaminobenzophenone, 3,3′-diaminobenzophenone, 2-nitro-1,4-diamino Examples thereof include benzene, 3,3′-dinitro-4,4′-diaminobiphenyl, 3,3′-dimethoxy-4,4′-diaminobiphenyl, 1,5-diaminonaphthalene and the like.

  As the aromatic diamine, those introduced with a hydroxyl group, a pyridine group, an oxycarbonyl group or a tertiary amine group can also be used. These can increase the solubility in an alkali developer. For example, 2,6-diaminopyridine, 3,5-diaminopyridine, 3,5-diamino-2,4-dimethylpyridine, 1,4-diamino-2-hydroxybenzene, 3,3′-dihydroxy-4,4 Examples include '-diaminobiphenyl, bis (3-amino-4-hydroxyphenyl) hexafluoropropane, and 2-hydroxy-1,4-diaminobenzene.

（式（１１）において、Ｒ⁷は２価の炭化水素残基であり、ｋは１〜１０の整数である。） Examples of the diaminosilane compound include diaminosiloxane. Specifically, 1,3-bis (3-aminopropyl) -1,1,3,3-tetramethyldisiloxane, diaminosiloxane represented by the formula (11), and the like.

(In the formula (11), R ⁷ is a divalent hydrocarbon residue, and k is an integer of 1 to 10.)

これらのジアミン成分は、単独又は組み合わせて用いることができる。 Moreover, the diamine shown to Formula (12) can be mentioned as an aromatic diamine, an aliphatic diamine, and an alicyclic diamine other than the above.

These diamine components can be used alone or in combination.

  Moreover, you may introduce | transduce an epoxy group in a polyimide unit in the soluble polyimide (A) shown by Formula (1) of this invention. For example, an epoxy group can be introduced by modifying a modifiable functional group of the diamine component with epichlorohydrin or the like. Examples of the functional group that can be modified include a hydroxyl group and a carboxyl group. Epoxy groups are highly reactive with amines and can crosslink with amines generated from photobase generators, resulting in a difference in solubility and / or dissolution rate between irradiated and unirradiated areas during alkali development. Make it easy to do. Examples of the diamine component having such a functional group that can be modified include 1,4-diamino-2-hydroxybenzene, 3,3′-dihydroxy-4,4′-diaminobiphenyl, and the formula (8). Such as diamine.

  The soluble polyimide (A) includes a unit having a carboxyl group and a unit having no carboxyl group, and the composition is indicated by x and y. Specifically, x is an integer of 1 or more, and y is an integer of 0 or more. The unit having a carboxyl group can be introduced in such a range that the soluble polyimide (A) can express solvent solubility and the photosensitive resin composition can express alkali developability. The ratio of (number of units containing carboxyl groups) / (total units x + y) is preferably within the range of 0.01 to 1, more preferably 0.2 to 0.9, and even more preferably 0. .3 or more and 0.8 or less. Soluble polyimide (A) is preferred because it has excellent physical properties of the cured product when the photosensitive resin composition of the present invention is cured, and can be suitably used in this range of composition.

（式中のα、β、ａ、ｂ、ｘ、ｙは前記と同じ意味を持つ。Ｗは光照射のみにより、もしくは光照射及び加熱により架橋し得る官能基、又は光塩基発生剤（Ｂ）に由来するアミンの存在下で光照射のみにより、もしくは光照射及び加熱により架橋し得る官能基を有する末端構造を表す。） In the photosensitive resin composition of the present invention, the soluble polyimide (A) is present in the presence of an amine derived from a functional group that can be crosslinked only by light irradiation or by light irradiation and heating, or a photobase generator (B). It may have a terminal structure W having a functional group that can be crosslinked only by light irradiation or by light irradiation and heating, and is preferably represented by the formula (3).

(In the formula, α, β, a, b, x, and y have the same meaning as described above. W is a functional group that can be crosslinked only by light irradiation or by light irradiation and heating, or a photobase generator (B). Represents a terminal structure having a functional group that can be crosslinked only by light irradiation in the presence of an amine derived from or by light irradiation and heating.)

  Examples of functional groups that can be crosslinked only by light irradiation or by light irradiation and heating include vinyl groups, functional groups having cinnamic acid, maleimide groups, diazo groups, azide groups, and the like. Examples of functional groups having cinnamic acid include a cinnamoyl group, a cinnamylideneacetyl group, a chalcone group, and a styrylpyridine group. Maleimide groups include a maleimide group, an α-phenylmaleimide group, and the like. Diazo groups include diazo groups and o-quinone diad groups. Examples of the azide group include a phenyl azide group, a sulfonyl azide group, and a carbonyl azide group. In addition, furylacryloyl group, coumarin, pyronyl group, anthracenyl group, benzophenonyl group, benzoin group, stilbene group, dithiocarbamate group, xanthate group, 1,2,3-thiadiazolinyl group, cyclopropenyl group And aza-dioxabicyclo group.

  Specifically, the terminal structure W can be introduced, for example, by the following method. For example, cinnamic acid can be introduced into the terminal structure W by reacting cinnamic acid chloride with the amine terminal of polyimide.

（式（１３）におけるＲ⁸は前記β又はｂである。）

（式（１５）におけるＲ⁸は前記と同じ意味である。） A functional group that can be crosslinked only by light irradiation in the presence of an amine derived from a photobase generator, or by light irradiation and heating, can form a crosslinked structure with an amine and the functional group, or an amine serves as a catalyst. The functional groups can form a crosslink. Specifically, for example, a carboxyl group, an ethylenically unsaturated double bond, an acetylenic unsaturated bond, an epoxy group, an oxelan group, and the like. Specific examples of the terminal structure W include structures represented by formula (13), formula (14), or formula (15).

(R ⁸ in formula (13) is β or b.)

(R ⁸ in formula (15) has the same meaning as described above.)

  X in Formula (13) is a trivalent aromatic or aliphatic organic group, and can be introduced by end-capping the amine terminal with a tricarboxylic acid anhydride. Examples of the tricarboxylic acid anhydride include trimellitic anhydride and hexahydro trimellitic anhydride.

  Y in the formula (14) is a divalent aromatic or aliphatic organic group, which can be introduced by end-capping the acid anhydride terminal with a compound having a carboxyl group and a hydroxyl group in the same molecule. it can. Examples of such compounds include amino acids and aminobenzoic acids. An amino acid is, for example, glycine, alanine, parin, leucine, isoleucine, phenylalanine, proline whose substituent on the alpha carbon is hydrogen or an alkyl group; serine, threonine, tyrosine containing a hydroxyl group on the alpha carbon; alpha Substituents on carbon include cysteine and methionine containing an S atom; and aspartic acid and glutamic acid having two carboxyl groups. Aminobenzoic acids include o-aminobenzoic acid, m-aminobenzoic acid, p-aminobenzoic acid, and the like.

  Z in Formula (15) is a divalent organic group containing an ethylenically unsaturated double bond or an acetylenic unsaturated bond. Z can be introduced by end-capping the polyimide with an acid anhydride containing an ethylenically unsaturated double bond or an acetylenic unsaturated bond. Examples of the acid anhydride containing an ethylenically unsaturated double bond or an acetylenically unsaturated bond include maleic anhydride, 5-norbornene-2,3-dicarboxylic acid anhydride, cyclohexene dicarboxylic acid anhydride, bicyclo [2 2.2] Oct-7-ene-2,3-dicarboxylic anhydride, 4-phenylethylphthalic anhydride, and the like.

  In addition to the above, an epoxy group or an oxetane group can also be introduced into the terminal structure W of polyimide. For example, a compound having an amine terminal of polyimide and an epoxy group or oxetane group can be reacted and introduced. Moreover, the compound which has a carboxylic acid terminal of Formula (13) or Formula (14), and an epoxy group or an oxetane group can be made to react and introduce | transduce. Examples of the compound having an epoxy group or an oxetane group include epichlorohydrin.

  When the terminal of the soluble polyimide (A) is not a terminal structure W having a functional group capable of crosslinking, the terminal of the polyimide may be sealed with a dicarboxylic acid anhydride. Examples of the dicarboxylic anhydride used in this case include phthalic anhydride, phenylethylphthalic anhydride, succinic anhydride, cyclohexanedicarboxylic anhydride, methylnorbornane dicarboxylic anhydride, and the like.

  Soluble polyimide (A) can be synthesized by reaction of tetracarboxylic dianhydride and diamine. Solvents used in the synthesis are polar solvents such as N-methyl-2-pyrrolidone, N, N-dimethylacetamide, N, N-dimethylformamide, dimethylsulfoxide, tetramethylurea, hexanemethylphosphoric triamide, γ-butyrolactone, etc. Is mentioned. In addition to these solvents, ketones, esters, lactones, ethers, halogenated hydrocarbons, and hydrocarbons can be mentioned. For example, acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, methyl acetate, ethyl acetate, butyl acetate, diethyl oxalate, dimethyl carbonate, diethyl malonate, diethyl ether, isopropyl ether, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, tetrahydrofuran, dichloromethane, 1, 2-dichloroethane, chloroform, 1,4-dichlorobutane, trichloroethane, chlorobenzene, o-dichlorobenzene, hexane, heptane, octane, benzene, toluene, xylene and the like. These can be used alone or in combination of two or more.

  The soluble polyimide (A) can be obtained by mixing tetracarboxylic dianhydride and diamine in the solvent and reacting at 0 ° C to 200 ° C. The synthesis of the soluble polyimide (A) may be performed only by heating, or may be performed by adding a catalyst and heating. As the catalyst, for example, acid anhydrides, lactones, and bases can be used. Examples of acid anhydrides include acetic anhydride. The lactone is preferably γ-valerolactone, and the base is preferably pyridine and / or methylmorpholine.

  A tetracarboxylic dianhydride and a diamine are added to the solvent and heated to 150 to 200 ° C., preferably 160 to 180 ° C. in the presence of a catalyst to obtain a polyimide solution. The water produced by the imidation reaction can be removed from the reaction system together with a solvent azeotropic with water, such as toluene and xylene.

  As the photobase generator (B) capable of generating an amino group by light irradiation used in the present invention, a conventionally known photobase generator can be used. For example, acyloxyimino compounds, carbamoyl oxime compounds, carbamoyl hydroxylamine compounds, carbamic acid compounds, formamide compounds, acetamide compounds, carbamate compounds, benzyl carbamate compounds, nitrobenzyl carbamate compounds, sulfonamide compounds, imidazole derivative compounds, amine imide compounds, pyridine derivatives Compounds, α-aminoacetophenone derivative compounds, quaternary ammonium salt derivative compounds, α-lactone ring derivative compounds, amine imide compounds, phthalimide derivative compounds, and the like. Among these, a photobase generator that can generate 1 or more and 4 or less amino groups from one molecule by light irradiation is preferable.

（式中有機基Ｄは１価以上４価以下の有機基、Ｒ¹は２価の有機基、Ｒ²、Ｒ³はそれぞれ１価の有機基を示し、Ｒ²、Ｒ³の少なくとも一つは芳香族基を示す。ｍは０又は１であり、ｍが０のとき、前記Ｄの有機基が芳香族基でない。ｎは１以上４以下の整数であり、複数個のＲ¹、Ｒ²、Ｒ³はそれぞれ同一でも異なっていても良い。） Among photobase generators that can generate 1 to 4 amino groups from one molecule by light irradiation, acyloxyimino compounds are preferred, and in particular, from 1 molecule to 1 to 4 by light irradiation shown in formula (2). A photobase generator capable of generating an amino group is preferred.

(In the formula, the organic group D is a monovalent to tetravalent organic group, R ¹ is a divalent organic group, R ² and R ³ are each a monovalent organic group, and at least one of R ² and R ³ ) Represents an aromatic group, m is 0 or 1, and when m is 0, the organic group of D is not an aromatic group, n is an integer of 1 to 4, and a plurality of R ¹ , R ² and R ³ may be the same or different.

  First, the organic group D will be described. The organic group D is an organic group having an aromatic ring having a substitutable site of 1 to 4 valences, an organic group having a heterocyclic ring, an aliphatic organic group, or an alicyclic organic group. Examples of such an organic group having an aromatic ring include benzene, naphthalene, biphenyl, biphenylene, and the like. Examples of the organic group having a heterocycle include triazine, pyridine, pyrazine, pyrimidine, pyran, furan, thiophene, pyrrole, thiazole, imidazole, indole, quinoline, purine, pteridine, isocyanuric acid, tetrahydrofuran, and dioxane. It is done. Examples of such aliphatic organic groups include linear n-butane, n-pentane, n-hexane, n-heptane, n-octane, branched 2-methylpropane, 2-methylbutane. 2,2-dimethylpropane, 2-methylheptane, 3-methylheptane, 2-methylhexane, 3-methylhexane, 2,3-dimethylpentane, 3-ethylpentane, 2-methylheptane, 3-methylheptane, Examples include 4-methylheptane, 2,3-dimethylhexane, 2,4-dimethylhexane, 2,5-dimethylhexane, and 3-ethylhexane. Moreover, these may have an unsaturated bond. Examples of the alicyclic organic group include cyclobutane, cyclopentane, cyclohexane, cycloheptane, cyclooctane, cyclobutene having an unsaturated bond, cyclopentene, cyclohexene, cyclohexadiene, cycloheptene, cycloheptadiene, cycloheptatriene, Examples include cyclooctene, cyclooctadiene, cyclooctatriene, cyclooctatetraene, norbornane, norbornene, norbornadiene, bicyclo [2.2.2] oct-7-ene.

  The compound (2) of the present invention can be obtained, for example, by reacting an oxime compound with the corresponding carboxylic acid or carboxylic anhydride in the presence of a suitable condensing agent such as thionyl chloride, phosphorus pentachloride, dicyclohexylcarbodiimide and the like. it can. It can also be synthesized by reacting the corresponding acid chloride with an oxime compound in the presence of a suitable base catalyst such as triethylamine, pyridine, sodium halide and the like.

（式中の有機基Ｄ及びｎは前記と同じ意味を持つ。） The organic group D in the formula (2) can be introduced from the corresponding carboxylic acid, carboxylic acid anhydride, or acid chloride as a raw material. Although an example of a raw material is described below, these may be a corresponding carboxylic acid, carboxylic acid anhydride, or acid chloride, respectively. Moreover, the introduction site | part of the organic group D in these compounds respond | corresponds with the organic group D in Formula (2). The organic group D can be introduce | transduced by carboxylic acid represented by Formula (16), for example.

(The organic groups D and n in the formula have the same meaning as described above.)

有機基Ｄは例えば、式（１８）で表される、カルボン酸無水物より導入することもできる。

Examples of such carboxylic acid or carboxylic anhydride or acid chloride include phenylacetyl chloride as monocarboxylic acid, phenylenediacetic acid, succinic acid, cyclohexyldicarboxylic acid, cyclohexenedicarboxylic acid, methylnorbornanedicarboxylic acid as dicarboxylic acid. Examples of terephthalic acid, phenylethylphthalic acid, and tricarboxylic acid include hexahydrotrimellitic acid and compounds represented by the formula (17).

The organic group D can also be introduce | transduced from a carboxylic anhydride represented by Formula (18), for example.

なお、ｎが１以上４以下の条件が満たされれば、有機基Ｄは置換基を有していても良い。 Examples of such a compound include the aliphatic tetracarboxylic acid anhydride described in the formula (6).

Note that the organic group D may have a substituent as long as the condition that n is 1 or more and 4 or less is satisfied.

（式中Ｒ⁴は炭素数１以上４以下の有機基を示す）

（式中Ｒ⁵は水素又はメチル基又はエチル基を示し、Ｒ⁶は炭素数１以上４以下の有機基を示す。） Next, R ¹ will be described. R ¹ is a divalent organic group, such as an alkyl group, a group having an ester group represented by formula (19), a group having an amide group represented by formula (20), or the like. The alkyl group preferably has 1 to 4 carbon atoms, and examples thereof include a methylene group, an ethylene group, a propylene group, and a butylene group.

(Wherein R ⁴ represents an organic group having 1 to ⁴ carbon atoms)

(Wherein R ⁵ represents hydrogen, a methyl group, or an ethyl group, and R ⁶ represents an organic group having 1 to 4 carbon atoms.)

When R ¹ contains an amide group or an ester group, for example, the amide group is derived using various amino acids such as glycine and alanine, and the ester group is, for example, one hydroxyl group and at least one hydroxyl group in one molecule. It can be derived using a compound having a carboxyl group, such as glycolic acid or 3-hydroxypropionic acid.

Next, R ² and R ³ will be described. R ² and R ³ are monovalent organic groups, which may be the same or different from each other, but at least one of them must be an aromatic group. Examples of such an aromatic group include a phenyl group and the like having one aromatic ring, and a naphthyl group and a carbazole group and the like having two aromatic rings and having three aromatic rings. Examples include anthracenyl group and phenanthrenyl group, and examples having four aromatic rings include naphthacenyl group, pyrenyl group and perylenyl group. Moreover, these aromatic rings may have a substituent.

  Although there is no restriction | limiting in particular as a non-aromatic group which is a monovalent organic group, For example, hydrogen, an alkyl group, and an alkoxyl group are mentioned. The alkyl group preferably has 1 to 4 carbon atoms, and examples thereof include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, and a sec-butyl group. The alkoxyl group is preferably a phenoxy group or an alkoxyl group having 1 to 4 carbon atoms. Examples of such an alkoxyl group include a methoxy group, an ethoxy group, a butoxy group, an isobutoxy group, and a sec-butoxy group.

Examples of the photobase generator capable of generating 1 to 4 amino groups from one molecule by light irradiation that can be represented by the formula (2) include those having a structure as represented by the formula (21).

  Although there is no restriction | limiting in particular in the quantity of the photobase generator (B) to be used, from 1 weight part with respect to 100 weight part to soluble polyimide (A) in consideration of the photosensitivity and the mechanical characteristic of resin after hardening. It is preferable to blend 100 parts by weight. More preferably, it is 5 to 50 parts by weight.

  The photosensitive resin composition of the present invention may further contain a photosensitizer (C). There is no restriction | limiting in particular as a photosensitizer (C), A conventionally well-known photosensitizer can be used. For example, aromatic azides such as azidoanthraquinone and azidobenzalacetophenone, coumarin compounds such as coumarin, ketocoumarin, 3,3′-carbonylbis (diethylaminocoumarin), and 3-ketocoumarin; benzanthrone of aromatic ketones , Phenontolenquinone, benzyl, benzophenone, p, p'-tetramethyldiaminobenzophenone, etc .; aromatic amines N-phenyldiethanolamine, N-phenylglycine, p-nitroaniline, 2,4-dinitroaniline, 2-chloro -4-nitroaniline, 2,6-dinitro-4-nitroaniline, Michler's ketone, etc .; thioxanthone, thioxanthone, diethylthioxanthone, isopropylthioxanthone; aromatic hydrocarbons anthracene, naphtha Quinones anthraquinone, naphthoquinone, benzoquinone, etc .; emissions, diphenyl, p- nitro diphenyl. In addition, for example, coumarin compounds having a heterocyclic ring described in JP-A-3-239703 and JP-A-5-289335; 3-ketocoumarin compounds described in JP-A-63-221110; JP-A-4-221958 Xanthene dyes described in JP-A-4-219756; pyromethene dyes described in JP-A-6-19240; JP-A-47-2528; JP-A-54-155292; (P-dialkylaminobenzylidene) ketone and styryl dye described in JP-A-56-166154 and JP-A-59-56403; sensitizing dye having a julolidyl group described in JP-A-6-295061; And diaminobenzene compounds described in JP-A-11-326624. Of these, compounds having absorption in the vicinity of 300 to 450 nm are preferable, and specifically, coumarin compounds, thioxanthone compounds, and aromatic ketones are preferable.

  Although there is no restriction | limiting in particular in the quantity of the photosensitizer (C) to be used, in consideration of photosensitivity and the mechanical characteristic of resin after hardening, 1 to 50 parts by weight with respect to 100 parts by weight of the soluble polyimide (A). It is preferable to blend by weight. More preferably, it is 3 to 30 parts by weight.

  The photosensitive resin composition of the present invention may further contain an amidation catalyst (D). When the amidation catalyst is contained, the reaction between the generated amine and the carboxyl group in the soluble polyimide is promoted, so that the heating temperature after exposure / development can be lowered. As the amidation catalyst (D), for example, a compound that forms an active ester with a carboxyl group in soluble polyimide, or a compound that can increase the electrophilicity of the carboxyl group can be used. Examples of such compounds include boroxine compounds, N-hydroxy compounds, tertiary amines, phosphate esters, amine salts, urea compounds, organic acids, Lewis acids, and the like.

  Examples of boroxine compounds include 2,4,6-tris- (3,4,5-trifluorophenyl) boroxine, 2,4,6-tris- (3-nitrophenyl) boroxine, 2,4,6-tris- (3,5-ditrifluoromethylphenyl) boroxine, 2,4,6-tris- (4-trifluoromethylphenyl) boroxine and the like. Examples of the N-hydroxy compound include N-hydroxybenzotriazole, N-hydroxysuccinimide, N-hydroxyphthalimide, N-hydroxypiperidine and the like. Examples of the tertiary amine include triethylamine, pyridine, 4,4-dimethylaminopyridine, 1,5-diazabicyclo [4.3.0] -5-nonene. Examples of the phosphate ester include (2,3-dihydro-2-thioxo-3-benzoxazolyl) -phosphonic diphenyl ester. Examples of amine salts include 4- (4,6-dimethoxy-1,3,5-triazin-2-yl) -4-methylmorpholium chloride, p-toluenesulfonate of diazabicycloundecene, phenol Salts, octylates, formates, phthalates and the like. Examples of the urea compound include an N, N-dimethylurea derivative and a urea compound containing a urethane group in the same molecule. Examples of the organic acid include benzenesulfonic acid, acetic acid, trifluoroacetic acid, phenol, and the like. Examples of the Lewis acid include boron trifluoride diethyl ether complex. Of these, boroxine compounds are preferred.

  The amount of the amidation catalyst to be used is not particularly limited, but it is preferable to mix 1 part by weight to 20 parts by weight with respect to 100 parts by weight of the soluble polyimide in consideration of photosensitivity and mechanical properties of the cured resin. More preferably, it is 2 to 10 parts by weight.

  If necessary, an additive that is already known can be appropriately added to the photosensitive resin composition of the present invention. Specific additives include adhesion improvers, surfactants, antioxidants, UV inhibitors, light stabilizers, plasticizers, waxes, fillers, pigments, dyes, foaming agents, antifoaming agents, dehydration Agents, antistatic agents, antibacterial agents, antifungal agents, flame retardants, leveling agents, dispersants, radical polymerization initiators, ethylenically unsaturated compounds, and the like.

  The photosensitive resin composition of the present invention comprises a soluble polyimide (A), a photobase generator (B) capable of generating an amino group by light irradiation, and a photosensitizer (C), if necessary, an amidation. It can be obtained by mixing the catalyst (D) in an arbitrary solvent, or drying the solvent by an arbitrary method after mixing in the solvent.

  A circuit board can be produced using the photosensitive resin composition of the present invention. When manufacturing a circuit board, a resin composition layer is laminated on at least a substrate having wiring, pattern exposure is performed on the resin composition layer, and an aqueous alkaline solution is applied to the resin composition layer after the pattern exposure. Is used for development processing. The base material having wiring means, for example, a material having wiring on an arbitrary base material such as a hard base material such as a glass epoxy substrate or a glass maleimide substrate, or a flexible base material such as a polyimide film.

  Especially, the photosensitive resin composition of this invention can be used suitably as a coverlay of the flexible printed wiring board which has wiring on flexible base materials, such as a polyimide film. When the photosensitive resin composition of the present invention is used as a coverlay for a flexible printed wiring board, for example, a coating solution obtained by dissolving the photosensitive resin composition of the present invention with a solvent is applied onto a substrate having wiring. Alternatively, the solvent of this coating solution is dried to form a so-called dry film, which is pasted on a substrate having wiring.

  When adjusting a coating liquid, it can adjust using a solvent, for example. As the solvent, for example, general organic solvents such as N-methyl-2-pyrrolidone, N, N-dimethylacetamide, N, N-dimethylformamide, dimethylsulfoxide, and γ-butyrolactone can be used. . As the solvent used for the coating liquid, the solvent used when the soluble polyimide is synthesized can be used as it is. For example, the coating liquid is prepared by adjusting the reaction liquid at the time of synthesizing the soluble polyimide to an arbitrary concentration with the solvent, containing a photobase generator, and if necessary, a photosensitizer, an amidation catalyst, or an additive. Can be included and adjusted.

  Examples of the method for applying the coating liquid containing the photosensitive resin composition of the present invention onto the substrate having wiring include methods such as dipping, casting, spraying, screen printing, and spin coating. It is done. By such a method, a coating liquid is applied on the base material having wiring, and most of the solvent is heated and dried to form a coverlay on the base material having wiring. In this way, a base material having wiring, a cover lay formed on the base material so as to cover the wiring, and composed of a substance formed by exposing and developing the photosensitive resin composition of the present invention, The flexible printed wiring board which comprises can be produced.

  When using a dry film composed of the photosensitive resin composition of the present invention, the coating liquid is applied on an arbitrary carrier film such as a polyethylene terephthalate film or a metal film by an arbitrary method and then dried to form a dry film. A laminated film having a carrier film and a dry film is provided. Further, at least one arbitrary antifouling film such as a low-density polyethylene film or a protective film may be provided on the dry film to form a laminated film. This dry film is laminated on a substrate having wiring by an arbitrary method such as a heat laminating method, a hot pressing method, or a heat vacuum laminating method. In this way, a base material having wiring, a cover lay formed on the base material so as to cover the wiring, and composed of a substance formed by exposing and developing the photosensitive resin composition of the present invention, The flexible printed wiring board which comprises can be produced.

  Although there is no restriction | limiting in particular in the film thickness of the coverlay formed by these methods, From points, such as a circuit characteristic, it is preferable that it is 4-50 micrometers, It is more preferable that it is 6-40 micrometers, 10-30 micrometers It is particularly preferred.

  The photosensitive resin composition of the present invention can be developed with an aqueous alkali solution by causing a difference in solubility or / and a dissolution rate difference between an irradiated part and an unirradiated part only by light irradiation or by light irradiation and heating. Since it is a negative photosensitive resin composition, it is necessary after pattern exposure by irradiating light to the coverlay composed of this photosensitive resin composition through a negative mask on which a desired pattern is drawn. Depending on the heating. Next, after the unexposed portion is removed by dissolution with a suitable alkali developer, post-cure is performed as necessary. Thereby, a desired relief pattern is produced. The post cure temperature is preferably 100 ° C. or higher and 250 ° C. or lower. More preferably, it is 120 degreeC or more and 180 degrees C or less. Thereby, the coverlay of the flexible printed wiring board conventionally punched mechanically can be processed with light. As a result, a fine flexible printed circuit board that cannot be machined can be produced.

  The light source used for light irradiation is not particularly limited, and examples thereof include a high pressure mercury lamp, an ultrahigh pressure mercury lamp, a low pressure mercury lamp, a metal halide lamp, a xenon lamp, a fluorescent lamp, a tungsten lamp, an argon laser, and a helium cadmium laser. The aqueous alkali solution used for development is not particularly limited, and examples thereof include an aqueous sodium carbonate solution, an aqueous potassium hydroxide solution, an aqueous sodium hydroxide solution, and an aqueous tetramethylammonium hydroxide solution. The development method is not particularly limited, and examples include immersion development, paddle development, and spray development.

  In a conventionally known technique using a polyamic acid which is a polyimide precursor and a photobase generator, a base generated from the photobase generator in an exposure (light irradiation) part is used for salt formation of a carboxyl group in the polyamic acid. Alternatively, it is used as a catalyst for imidization, and the polyamic acid is partially imidized by heating to form a polyimide, thereby changing the solubility / or dissolution rate in an alkali developer.

  When the base is used to form a salt of a carboxyl group in the polyamic acid, the amount of the carboxyl group is too large because there is a carboxyl group for each repeating unit in the polyamic acid, and even if a salt is partially formed by the base. It is difficult to obtain a difference in solubility in a sufficient alkali developer / or a difference in dissolution rate. When the base is used as a catalyst for imidization, no base is generated from the photobase generator in the unexposed area, so that the imidization of the polyamic acid proceeds only by heating although there is no imidization catalyst. For this reason, the polyamic acid in the unexposed part is also partially polyimide. For this reason, this conventionally known technique is unlikely to cause a difference in solubility and / or a difference in dissolution rate with respect to an alkaline developer.

  The present invention uses a thermally stable polyimide and controls the amount of carboxyl groups in the polyimide to combine the photobase generator with a difference in solubility in an alkaline developer between the unexposed and exposed areas. It is possible to take skillfully.

  The carboxyl group in the soluble polyimide in the present invention can be introduced by using, as a monomer, one or more diamines selected from, for example, formula (8) as described above. At that time, the amount of the carboxyl group in the soluble polyimide can be controlled by the amount of one or more diamines selected from the formula (8) when the soluble polyimide is synthesized.

  The soluble polyimide can be synthesized using one or more tetracarboxylic dianhydrides described herein and two or more diamines described herein as monomers, wherein the diamine has the formula (7) It is essential to include one or more diamines selected from: At this time, as the amount of preparation, the molar ratio of (total tetracarboxylic dianhydride) / (total diamine) is preferably 0.95 or more and 1.05 or less. As the amount of one or more diamines selected from formula (7) among all diamines, the molar ratio of (one or more diamines selected from formula (7)) / (total diamines) is 0.01 or more and 1 or less. Preferably, it is 0.2 to 0.9, more preferably 0.3 to 0.8.

数式（１）において、ηは還元粘度であり、ｔ₀はＮＭＰ溶媒の流下時間であり、ｔは可溶性ポリイミドのＮＭＰ溶液の流下時間であり、ｃは溶液濃度（ｇ／ｄｌ）である。 The reduced viscosity represented by the formula (1) when a 1-methyl-2-pyrrolidone (abbreviated as NMP) solution of the synthesized soluble polyimide having a solution concentration of 0.5 g / dl is measured at 30 ° C. is 0.2 or more. It is preferably 1.5 or less, more preferably 0.3 or more and 1 or less, because when the film is formed, the photosensitive resin composition film has good alkali developability and good physical properties. As the viscometer used for the measurement of the reduced viscosity, for example, an Ubbelohde viscometer (manufactured by Shibata Kagaku Co., Ltd., viscometer number No. 1) can be used.

In Equation (1), η is the reduced viscosity, t ₀ is the flow time of the NMP solvent, t is the flow time of the NMP solution of soluble polyimide, and c is the solution concentration (g / dl).

  In the present invention, the mechanism of the decrease in the solubility and / or the decrease in the dissolution rate with respect to the alkaline developer in the exposed (light-irradiated) part is presumed to be due to the following action. When there is no terminal structure having a functional group capable of crosslinking, the exposed portion forms a salt between the amine generated from the photobase generator and the carboxyl group in the soluble polyimide (A), and takes a difference in solubility in an alkaline developer. Is possible. Alternatively, by heating at 100 ° C. to 180 ° C. after exposure, the amine generated from the photobase generator and the carboxyl group in the soluble polyimide (A) cause a chemical reaction to generate an amide bond. When the generated amine is bifunctional or more, a crosslinked structure is formed through an amide bond. It is possible to take a difference in solubility in an alkaline developer by forming a salt, blocking a carboxyl group with an amide bond, or forming a crosslinked structure with an amide bond with a bifunctional or higher amine.

  When the terminal structure W can form a crosslinked structure by light, the exposed portion forms a salt with the amine generated from the photobase generator and the carboxyl group in the soluble polyimide (A), and further forms a crosslinked structure with light. The functional group in the terminal structure to be obtained forms a crosslinked structure, so that it is possible to take a difference in solubility in an alkaline developer.

  In the case where the terminal structure W can form a crosslinked structure by light and heat, in the exposed portion, the amine generated from the photobase generator and the carboxyl group in the soluble polyimide (A) form a salt, and further, the crosslinked structure is formed by light. Functional groups in the terminal structure that can be formed form a crosslinked structure. Further, when heated at 100 ° C. to 180 ° C., an amine generated from the photobase generator reacts with a carboxyl group in the soluble polyimide (A) or a functional group in the terminal structure to form a crosslinked structure to form an alkali. It is possible to take a difference in solubility in the developer.

Next, examples performed for clarifying the effects of the present invention will be described.
(Soluble polyimide synthesis example 1)
In a 500 ml separable flask under nitrogen atmosphere, 28.629 g (0.1 mol) of 3,3′-dicarboxy-4,4′-diaminodiphenylmethane (manufactured by Wakayama Seika Co., Ltd.), 82.35 g of N-methylpyrrolidone, After stirring γ-butyrolactone 152.94 g, 0.5925 g (0.004 mol) of phthalic anhydride (manufactured by Wako Pure Chemical Industries, Ltd.) was added and stirred at room temperature for 30 minutes. 29.425 g (0.098 mol) of Ricacid TDA-100 (manufactured by Shin Nippon Chemical Co., Ltd.) was added and stirred at room temperature for 2 hours. A separable flask is equipped with a moisture meter and a condenser, 40 g of toluene, 3.64 g of pyridine, and 3.00 g of γ-valerolactone are added, the reaction temperature is increased to 180 ° C., and water is removed while refluxing. Stir for 3.5 hours. The mixture was further stirred for 2 hours while removing the distilled components, then cooled to room temperature, and the obtained polyimide solution was recovered to obtain a soluble polyimide varnish 1. The polyimide concentration calculated from the charged weight and the recovered weight was 20% by weight (100 parts by weight in terms of polyimide). The reduced viscosity in a 0.5 g / dl NMP solution was 0.57.

(Soluble polyimide synthesis example 2)
Synthesis was carried out in the same manner as in Synthesis Example 1 except that 0.769 g (0.004 mol) of trimellitic anhydride (manufactured by Wako Pure Chemical Industries, Ltd.) was used instead of phthalic anhydride of Synthesis Example 1. This was designated as soluble polyimide varnish 2. The polyimide concentration calculated from the charged weight and the recovered weight was 20% by weight (100 parts by weight in terms of polyimide). The reduced viscosity in a 0.5 g / dl NMP solution was 0.54.

(Photobase generator synthesis example 1)
19.47 g (0.10 mol) of 1,3-phenylenediacetic acid (manufactured by Wako Pure Chemical Industries, Ltd.) and 28.18 g (0.21 mol) of acetophenone oxime are dissolved in DMAc (dimethylacetamide), and dicyclohexylcarbodiimide and 1 are used as a condensing agent. -Hydroxybenzotriazole was added in an amount of 1.05 mol of acetophenone oxime. After stirring at room temperature, the precipitate was removed by filtration, and the resulting reaction solution was added dropwise to water. The precipitated oil was collected and purified with cyclohexane-ethyl acetate to collect the precipitate. The recovered compound was designated as photobase generator 1.

(Evaluation example)
Compounding was performed at the compounding ratio shown in Table 1 below, and each was coated on a silicon substrate with a spin coater, and the solvent was removed at 100 ° C. for 5 minutes to form a polyimide film of about 15 μm on the substrate. The film thickness of the film was measured using a surface shape measuring device DekTak6M (manufactured by ULVAC).

(Example of remaining film rate evaluation)
Half of the silicon substrate was shielded with a mask and exposed using a 400 W high pressure mercury lamp exposure machine HC-98 (manufactured by Sen Special Light Source). After the exposure, post-cure was performed on a hot plate at 180 ° C./3 minutes, allowed to cool to room temperature, and then developed with alkali. Alkali development was performed until the substrate was immersed in a 2% NaOH aqueous solution and the unexposed portion shielded from light with a mask was dissolved. After the development, the film was washed with water, and the remaining film ratio was calculated from the film thickness before development and the film thickness after development in the exposed area. The results are shown in Table 2 below. In Table 2, the remaining film rate is 90% or more, ◎, the remaining film rate is 80% or more, ◯, the remaining film rate is 50% or more, and the remaining film rate is less than 50%. As can be seen from Table 2, the remaining film ratio was good in both cases of Formulation 1 and Formulation 2.

Further, the residual film ratio when the exposure amount was 3,000 mJ / cm ² and the post-cure temperature was lowered to 150 ° C. to 180 ° C. was examined in the same manner as described above. The results are shown in Table 3 below. In Table 3, the remaining film ratio is 90% or more, ◎, the remaining film ratio is 80% or more, ◯, the remaining film ratio is 50% or more, and the remaining film ratio is less than 50%. As can be seen from Table 3, the remaining film rate was good in both cases of Formulation 1 and Formulation 2 even when the treatment was performed at a low temperature.

(Example of patterning evaluation)
These substrates were subjected to pattern exposure with a high-pressure mercury lamp using a mask aligner MA-10 (manufactured by Mikasa Co., Ltd.). Exposure was performed at 3,000 mJ / cm ² , and post-cure was performed at 180 ° C./3 minutes on a hot plate. Development was allowed to cool at room temperature, and was performed at 40 ° C. for 30 seconds by immersion in a 2% aqueous NaOH solution.

  In both cases of Formulation 1 and Formulation 2, a negative pattern was confirmed with L / S (line / space) = 50 μm / 50 μm. As shown in these examples, according to the present invention, negative photolithography using polyimide is possible by heat treatment at a low temperature of about 150 ° C. to 180 ° C.

  The present invention is not limited to the embodiment described above, and can be implemented with various modifications. For example, the numerical values, substances, amounts, measuring devices, and the like in the above embodiments can be variously changed and implemented without departing from the scope of the present invention.

  The present invention can be applied to a photosensitive coverlay capable of alkali development.

Claims (14)

A photosensitive resin composition comprising a soluble polyimide (A) represented by the formula (1) and a photobase generator (B) capable of generating an amino group by light irradiation.

(Wherein α is a tetravalent organic group, β is a divalent organic group having at least one carboxyl group, a is a tetravalent organic group, and b is a divalent organic group. X represents an integer of 1 or more, and y represents an integer of 0 or more)   The photosensitive resin composition is a negative photosensitive resin composition that can be developed with an alkaline aqueous solution by causing a difference in solubility and / or a difference in dissolution rate between an irradiated part and an unirradiated part by light irradiation and / or heating. The photosensitive resin composition according to claim 1, wherein the composition is a photosensitive resin composition.   3. The photosensitive resin according to claim 1, wherein the photobase generator (B) is a photobase generator capable of generating 1 to 4 amino groups from one molecule by light irradiation. Composition. The said photobase generator (B) is represented by Formula (2), The photosensitive resin composition in any one of Claims 1-3 characterized by the above-mentioned.

(In the formula, the organic group D is a monovalent to tetravalent organic group, R ¹ is a divalent organic group, R ² and R ³ are each a monovalent organic group, and at least R ² and R ³ One represents an aromatic group, m is 0 or 1, and when m is 0, the organic group of D is not an aromatic group, n is an integer of 1 to 4, and a plurality of R ¹ , R ² and R ³ may be the same or different.   The photosensitive resin composition according to any one of claims 1 to 4, wherein the divalent organic group represented by b in the formula (1) is a divalent organic group having a siloxane skeleton. . The soluble polyimide (A) can be crosslinked only by light irradiation or by light irradiation in the presence of a functional group that can be crosslinked by light irradiation and heating, or an amine derived from the photobase generator (B), or by light irradiation and The photosensitive resin composition according to any one of claims 1 to 5, which has a terminal structure W having a functional group capable of being crosslinked by heating, and is represented by the formula (3).

(Α, β, a, b, x, and y in the formula are the same as those in the formula (1).)   The photosensitive resin composition according to any one of claims 1 to 6, wherein the photosensitive resin composition further contains a photosensitizer (C).   The photosensitive resin composition according to any one of claims 1 to 7, wherein the photosensitive resin composition further contains an amidation catalyst (D).   Using the photosensitive resin composition according to any one of claims 1 to 8, a step of forming a resin composition layer on a substrate having at least wiring, and pattern exposure to the resin composition layer And a step of developing the resin composition layer after the pattern exposure using an alkaline aqueous solution.   A circuit board obtained by the method according to claim 9.   A substrate obtained by exposing and developing the photosensitive resin composition according to any one of claims 1 to 8, which is formed on the substrate so as to cover the wiring and a substrate having wiring. A circuit board comprising: a coverlay comprising:   A film comprising the photosensitive resin composition according to any one of claims 1 to 8.   A laminated film comprising: a carrier film; and the film according to claim 12 provided on the carrier film.   The laminated film according to claim 13, further comprising a cover film formed on the film.