JP6462983B2 - Photosensitive thermosetting resin composition and flexible printed wiring board - Google Patents

Description

  The present invention relates to a photosensitive thermosetting resin composition and a flexible printed wiring board, and more specifically, a photosensitive thermosetting resin that can be developed with an alkali and is excellent in flame retardancy, folding resistance, and insulation reliability. The present invention relates to a flexible printed wiring board provided with a composition and a cured product of the photosensitive thermosetting resin composition.

  In recent years, the spread of smartphones and tablet terminals and the improvement of performance are progressing rapidly. Information equipment terminals represented by these are highly demanded by consumers for downsizing and thinning, and in order to meet these demands, it is necessary to increase the density of circuit boards inside the products and save space. Therefore, the use of flexible printed wiring boards that can be folded and stored and that can increase the degree of freedom of circuit arrangement is expanding, and the reliability for flexible printed wiring boards is required to be higher than ever. Yes.

  Currently, a cover lay based on polyimide is used for the bent part (bent part) as an insulating film for ensuring the insulation reliability of the flexible printed wiring board, and the mounting part (non-bent part) is photosensitive. A mixed loading process using a conductive resin composition is widely employed (see Patent Documents 1 and 2). Polyimide is excellent in mechanical properties such as heat resistance and flexibility, while the photosensitive resin composition used in the mounting part has characteristics such as excellent electrical insulation and solder heat resistance and can be finely processed. .

  Printed wiring boards, particularly flexible printed wiring boards (hereinafter abbreviated as FPC), are required to have high flame retardancy, and an insulating film that is one of the main components thereof is also excellent in flame retardancy. Is required. An FPC using a polyimide substrate or the like as a substrate is a thin film as compared with a printed wiring board of a glass epoxy substrate. On the other hand, since the required film thickness of the insulating film is the same for both the printed wiring board and the FPC, in the case of a thin FPC, the burden of making the insulating film flame-retardant is relatively increased.

  Therefore, various proposals have conventionally been made for flame retarding of insulating films. For example, a phosphorus-containing compound capable of imparting flame retardancy to a resin composition or an epoxy resin excellent in heat resistance is used to obtain an insulating film. Blending into a curable resin composition has been performed. For example, Patent Document 3 discloses that (a) a binder polymer such as an epoxy resin, (b) a halogenated aromatic ring such as a bromophenyl group, and a polymerizable ethylenically unsaturated bond such as a (meth) acryloyl group in the molecule. A flame retardant photosensitive resin composition for FPC, comprising: (c) a photopolymerization initiator; (d) a blocked isocyanate compound; and (e) a phosphorus-containing compound having a phosphorus atom in the molecule. Is disclosed.

Japanese Patent Application Laid-Open No. Sho 62-263692 Japanese Unexamined Patent Publication No. 63-110224 JP 2007-10794 A

Conventional photosensitive resin compositions contain a (meth) acrylate monomer in order to adjust viscosity, improve physical properties of a cured coating film, and improve sensitivity. Since the (meth) acrylate monomer is relatively flammable and the flame retardancy of the photosensitive resin composition is impaired, it is necessary to add a large amount of a flame retardant such as a phosphorus-containing compound to compensate for it.
However, when a phosphorus-containing compound is added to the photosensitive resin composition, the folding resistance is deteriorated, and cracks are likely to occur in the cured coating film at the time of cutting processing of a wiring board or a thermal shock test. In addition, many phosphorus-containing compounds have a phosphate ester skeleton, and there is a problem that ionic impurities increase due to their blending and the insulation reliability of the photosensitive resin composition decreases.

  Accordingly, an object of the present invention is to provide a photosensitive thermosetting resin composition excellent in flame retardancy, folding resistance and insulation reliability, and a flexible printed wiring board provided with a cured product of the photosensitive thermosetting resin composition. It is to provide.

As a result of intensive studies to solve the above-mentioned problems, the inventors of the present invention have photosensitive thermosetting including a polyimide resin having an imide ring and a carboxyl group, a photobase generator, a thermosetting component, and a reactive flame retardant. It discovered that the said subject could be solved by setting it as a resin composition.
That is, a photobase generator is activated by light irradiation, and a polyimide resin having a carboxyl group and a thermosetting component are subjected to an addition reaction by heating using the generated base as a catalyst, whereby only an unexposed portion is removed with an alkaline solution. It has been found that this is possible. As a result, fine processing by alkali development becomes possible, and it can be expected to obtain a cured product having excellent reliability.
In addition, since the resin having an imide ring is excellent in flame retardancy by itself, it is not necessary to add a large amount of flame retardant, and bending resistance derived from the flame retardant and insulation reliability deterioration can be avoided. Furthermore, it was found that by using a flame retardant as a reactive compound, the compound is incorporated into the curing system, and excellent flame retardancy and insulation reliability can be obtained even in a smaller amount. The present invention has been completed based on such findings.

That is, the photosensitive thermosetting resin composition of the present invention is
(A) a polyimide resin having an imide ring and a carboxyl group,
(B) a photobase generator (C) a thermosetting component, and
(D) Flame retardant
And (D) the flame retardant is a reactive compound.

  In the photosensitive thermosetting resin composition of the present invention, the (D) flame retardant is preferably a compound having reactivity with the (C) thermosetting component, more preferably the (D) flame retardant. Is a phosphorus-containing compound having a phenolic hydroxyl group. Moreover, it is preferable not to contain a (meth) acrylate monomer substantially. Further, the (A) polyimide resin having an imide ring and a carboxyl group preferably has a phenolic hydroxyl group. Furthermore, the (C) thermosetting component is preferably a cyclic ether compound. Furthermore, it is suitable for a flexible wiring board.

  Moreover, the dry film of this invention has a resin layer which consists of the said photosensitive thermosetting resin composition, It is characterized by the above-mentioned.

  Furthermore, the printed wiring board of this invention is equipped with the hardened | cured material formed using the said photosensitive thermosetting resin composition or the said dry film, It is characterized by the above-mentioned.

  According to the present invention, there is provided a photosensitive thermosetting resin composition capable of developing with an alkali and having excellent flame retardancy, folding resistance and insulation reliability, and a cured product of the photosensitive thermosetting resin composition. A flexible printed wiring board can be provided. The photosensitive thermosetting resin composition of the present invention is suitable for a process for forming an insulating film of a flexible printed wiring board, particularly a bent part (bent part) and a mounting part (non-bent part). The photosensitive thermosetting resin composition of the present invention is also suitable as a resin composition for a cover layer of a multilayer coverlay. Here, the cover layer refers to an outer resin layer of a cover lay having a laminated structure of two or more layers that is not in contact with the flexible printed circuit board.

It is process drawing which shows typically an example of the manufacturing method of the flexible printed wiring board of this invention.

Hereinafter, embodiments of the present invention will be described in detail.
The photosensitive thermosetting resin composition of the present invention comprises (A) a polyimide resin having an imide ring and a carboxyl group, (B) a photobase generator, (C) a thermosetting component, and (D) a flame retardant, (D) The flame retardant is a reactive compound.

The photosensitive thermosetting resin composition of the present invention uses a base generated from a photobase generator as a catalyst, causes a polyimide resin having a carboxyl group and a thermosetting component to undergo an addition reaction by heating after exposure, and removes an unexposed portion. It is a resin composition that can be developed by removing it with an alkaline solution. Thereby, it is not necessary to add a (meth) acrylate monomer, which is necessary in a photosensitive resin composition utilizing a polymerization reaction by radicals generated from a conventional photo radical polymerization initiator.
The (meth) acrylate monomer is flammable, and by not containing it substantially, it is possible to avoid a decrease in flame retardancy of the photosensitive thermosetting resin composition. For this reason, it is not necessary to add a large amount of a flame retardant typified by a phosphorus-containing compound, and it becomes possible to suppress a decrease in folding resistance and a decrease in insulation reliability due to the phosphorus-containing compound. Therefore, it is preferable that the photosensitive thermosetting resin composition of this invention does not contain a (meth) acrylate monomer substantially. Here, substantially not containing a (meth) acrylate monomer means that it is not actively blended as a constituent component, and it is not excluded that it is contained in a small amount as long as the effects of the present invention are not impaired. For example, the (meth) acrylate monomer is usually blended in an amount of about 20 to 50 parts by mass with respect to 100 parts by mass of the photosensitive resin in order to obtain the blending effect, but the photosensitive thermosetting resin composition of the present invention. In (A), it is preferably 15 parts by mass or less, more preferably 10 parts by mass or less with respect to 100 parts by mass of the polyimide resin having an imide ring and a carboxyl group as component (A).

In addition, the photosensitive thermosetting resin composition of the present invention has a flame retardant incorporated into the curing system by making the flame retardant a reactive compound, preferably a compound having reactivity with a thermosetting component, Even with a smaller amount, excellent flame retardancy and insulation reliability can be obtained.
More preferably, the flame retardant is a phosphorus-containing compound having a phenolic hydroxyl group. The photosensitive thermosetting resin composition of the present invention causes an alkali-soluble resin having an imide ring and a thermosetting component to undergo an addition reaction by heating after exposure using a base generated from a photobase generator as a catalyst, and thereby unexposed portions. Can be developed with an alkaline solution. However, when a phosphorus-containing compound having a phenolic hydroxyl group is used as a flame retardant, the post-exposure can be performed compared to the case of using a compound having no phenolic hydroxyl group. During the heat curing reaction (at the time of the following PEB step), it is possible to lengthen the time until alkali resistance is achieved by the addition reaction under the same heating temperature. Moreover, the selection range of the heating temperature at the time of thermosetting reaction (at the time of the following PEB process) can be expanded. From these things, the workability | operativity and handleability of a resin composition improve. It is also possible to suppress the occurrence of so-called fogging in which the unexposed portion becomes resistant to alkali.

The photosensitive thermosetting resin composition of the present invention is suitable for resin insulating layers of flexible printed wiring boards, such as coverlays and solder resists.
When forming the resin insulation layer of a flexible printed wiring board using the photosensitive thermosetting resin composition of this invention, a suitable manufacturing method is as follows. That is, a step of forming a resin layer comprising the photosensitive thermosetting resin composition of the present invention on a flexible printed wiring board, a step of irradiating the resin layer with light in a pattern, and a step of heating the resin layer (Post Exposure Bake) ; Also referred to as PEB), and a step of alkali-developing the resin layer to form a resin insulating layer having a pattern. After alkali development, further light irradiation and heat curing (post-cure) are performed to completely cure the resin composition to obtain a highly reliable resin insulation layer.
As described above, the photosensitive thermosetting resin composition of the present invention is preferably a negative by alkaline development by an addition reaction between a carboxyl group and a thermosetting component by selective heat treatment after light irradiation. Mold pattern formation is possible.
Since the resulting cured product is excellent in heat resistance and flexibility and can be finely processed by alkali development, it is not necessary to partially use an alkali development type photosensitive resin composition for polyimide, It can be used for both the bent part (bent part) and the mounting part (non-bent part) of the flexible printed wiring board, and is suitable for the batch formation process of the bent part (bent part) and the mounting part (non-bent part). .
Hereinafter, each component will be described in detail.

上記式（１）で表される部分構造は、下記式（２）または（３）で表されるものであることがより好ましい。

カルボキシル基の位置は特に限定されない。上記イミド環もしくはそれと結合する基の置換基としてカルボキシル基が存在してもよく、アミン成分やイソシアネート成分として、カルボキシル基を有するものを用いて合成することによってカルボキシル基をポリイミド樹脂に導入してもよい。 [(A) Polyimide resin having imide ring and carboxyl group]
In the present invention, (A) a polyimide resin having an imide ring and a carboxyl group is a resin having a carboxyl group and an imide ring.
The polyimide resin as component (A) preferably has a partial structure represented by the following formula (1) as an imide ring. In formula (1), it is preferable that R contains an aromatic ring.

The partial structure represented by the above formula (1) is more preferably one represented by the following formula (2) or (3).

The position of the carboxyl group is not particularly limited. A carboxyl group may be present as a substituent of the imide ring or a group bonded thereto, and the carboxyl group may be introduced into a polyimide resin by synthesis using an amine component or an isocyanate component having a carboxyl group. Good.

  Moreover, what has a phenolic hydroxyl group is preferable as a polyimide resin of the said (A) component. When a phenolic hydroxyl group is present, the time until it becomes alkali resistant by the addition reaction at the same heating temperature during the heat curing reaction after exposure (during the following PEB step) is longer than when it does not exist. Can do. Moreover, the selection range of the heating temperature at the time of thermosetting reaction (at the time of the following PEB process) can be expanded. From these things, the workability | operativity and handleability of a resin composition improve. It is also possible to suppress the occurrence of so-called fogging in which the unexposed portion becomes resistant to alkali.

  A well-known and usual method can be used for the synthesis | combination of the polyimide resin which is (A) component. For example, the resin obtained by making a carboxylic anhydride component react with an amine component and / or an isocyanate component is mentioned. Imidization may be performed by thermal imidization, chemical imidization, or a combination thereof.

  Examples of the carboxylic acid anhydride component include tetracarboxylic acid anhydrides and tricarboxylic acid anhydrides, but are not limited to these acid anhydrides, and acid anhydride groups that react with amino groups and isocyanate groups, and Any compound having a carboxyl group can be used, including derivatives thereof. Moreover, these carboxylic anhydride components may be used individually by 1 type, and may be used in combination of 2 or more type.

  Examples of the tetracarboxylic acid anhydride include pyromellitic dianhydride, 3-fluoropyromellitic dianhydride, 3,6-difluoropyromellitic dianhydride, 3,6-bis (trifluoromethyl) pyro Merit acid dianhydride, 3,3 ′, 4,4′-benzophenone tetracarboxylic dianhydride, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, 4,4′-oxydiphthalic acid Anhydride, 2,2′-difluoro-3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, 5,5′-difluoro-3,3 ′, 4,4′-biphenyltetracarboxylic acid Anhydride, 6,6′-difluoro-3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, 2,2 ′, 5,5 ′, 6,6′-hexafluoro-3,3 ′ , 4,4'-biphenyltet Carboxylic dianhydride, 2,2′-bis (trifluoromethyl) -3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, 5,5′-bis (trifluoromethyl) -3, 3 ′, 4,4′-biphenyltetracarboxylic dianhydride, 6,6′-bis (trifluoromethyl) -3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, 2,2 ′ , 5,5′-tetrakis (trifluoromethyl) -3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, 2,2 ′, 6,6′-tetrakis (trifluoromethyl) -3, 3 ′, 4,4′-biphenyltetracarboxylic dianhydride, 5,5 ′, 6,6′-tetrakis (trifluoromethyl) -3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride , And 2,2 ', 5,5', 6,6 -Hexakis (trifluoromethyl) -3,3 ', 4,4'-biphenyltetracarboxylic dianhydride, 1,2,3,4-benzenetetracarboxylic dianhydride, 3,3 ", 4,4 "-Terphenyltetracarboxylic dianhydride, 3,3 '", 4,4' "-quaterphenyltetracarboxylic dianhydride, 3,3" ", 4,4" "-kinkphenyltetracarboxylic acid Dianhydride, methylene-4,4′-diphthalic dianhydride, 1,1-ethynylidene-4,4′-diphthalic dianhydride, 2,2-propylidene-4,4′-diphthalic dianhydride 1,2-ethylene-4,4′-diphthalic dianhydride, 1,3-trimethylene-4,4′-diphthalic dianhydride, 1,4-tetramethylene-4,4′-diphthalic acid Anhydride, 1,5-pentamethylene-4,4'-diph Talic dianhydride, 2,2-bis (3,4-dicarboxyphenyl) -1,1,1,3,3,3-hexafluoropropane dianhydride, difluoromethylene-4,4′-diphthal Acid dianhydride, 1,1,2,2-tetrafluoro-1,2-ethylene-4,4′-diphthalic dianhydride, 1,1,2,2,3,3-hexafluoro-1, 3-trimethylene-4,4′-diphthalic dianhydride, 1,1,2,2,3,3,4,4-octafluoro-1,4-tetramethylene-4,4′-diphthalic dianhydride 1,1,2,2,3,3,4,4,5,5-decafluoro-1,5-pentamethylene-4,4′-diphthalic dianhydride, thio-4,4′- Diphthalic dianhydride, sulfonyl-4,4′-diphthalic dianhydride, 1,3-bis (3,4-dicarboxyphene) ) -1,1,3,3-tetramethylsiloxane dianhydride, 1,3-bis (3,4-dicarboxyphenyl) benzene dianhydride, 1,4-bis (3,4-dicarboxyphenyl) ) Benzene dianhydride, 1,3-bis (3,4-dicarboxyphenoxy) benzene dianhydride, 1,4-bis (3,4-dicarboxyphenoxy) benzene dianhydride, 1,3-bis [ 2- (3,4-Dicarboxyphenyl) -2-propyl] benzene dianhydride, 1,4-bis [2- (3,4-dicarboxyphenyl) -2-propyl] benzene dianhydride, bis [ 3- (3,4-dicarboxyphenoxy) phenyl] methane dianhydride, bis [4- (3,4-dicarboxyphenoxy) phenyl] methane dianhydride, 2,2-bis [3- (3,4- Dicarboxyphenoxy Phenyl] propane dianhydride, 2,2-bis [4- (3,4-dicarboxyphenoxy) phenyl] propane dianhydride, 2,2-bis [3- (3,4-dicarboxyphenoxy) phenyl] -1,1,1,3,3,3-hexafluoropropane dianhydride, 2,2-bis [4- (3,4-dicarboxyphenoxy) phenyl] propane dianhydride, bis (3,4- Dicarboxyphenoxy) dimethylsilane dianhydride, 1,3-bis (3,4-dicarboxyphenoxy) -1,1,3,3-tetramethyldisiloxane dianhydride, 2,3,6,7-naphthalene Tetracarboxylic dianhydride, 1,2,5,6-naphthalenetetracarboxylic dianhydride, 3,4,9,10-perylenetetracarboxylic dianhydride, 2,3,6,7-anthracenetetracarboxylic Acid dianhydride, 1,2,7,8-phenanthrenetetracarboxylic dianhydride, 1,2,3,4-butanetetracarboxylic dianhydride, 1,2,3,4-cyclobutanetetracarboxylic acid Anhydride, cyclopentanetetracarboxylic dianhydride, cyclohexane-1,2,3,4-tetracarboxylic dianhydride, cyclohexane-1,2,4,5-tetracarboxylic dianhydride, 3,3 ′ , 4,4′-bicyclohexyltetracarboxylic dianhydride, carbonyl-4,4′-bis (cyclohexane-1,2-dicarboxylic acid) dianhydride, methylene-4,4′-bis (cyclohexane-1, 2-dicarboxylic acid) dianhydride, 1,2-ethylene-4,4′-bis (cyclohexane-1,2-dicarboxylic acid) dianhydride, 1,1-ethynylidene-4,4′-bis (cyclohexane) San-1,2-dicarboxylic acid) dianhydride, 2,2-propylidene-4,4'-bis (cyclohexane-1,2-dicarboxylic acid) dianhydride, 1,1,1,3,3,3 -Hexafluoro-2,2-propylidene-4,4'-bis (cyclohexane-1,2-dicarboxylic acid) dianhydride, oxy-4,4'-bis (cyclohexane-1,2-dicarboxylic acid) dianhydride Thio-4,4′-bis (cyclohexane-1,2-dicarboxylic acid) dianhydride, sulfonyl-4,4′-bis (cyclohexane-1,2-dicarboxylic acid) dianhydride, 3,3 ′ -Difluorooxy-4,4'-diphthalic dianhydride, 5,5'-difluorooxy-4,4'-diphthalic dianhydride, 6,6'-difluorooxy-4,4'-diphthalic acid Anhydride, 3, 3 ', 5, 5', 6 6′-hexafluorooxy-4,4′-diphthalic dianhydride, 3,3′-bis (trifluoromethyl) oxy-4,4′-diphthalic dianhydride, 5,5′-bis (tri Fluoromethyl) oxy-4,4′-diphthalic dianhydride, 6,6′-bis (trifluoromethyl) oxy-4,4′-diphthalic dianhydride, 3,3 ′, 5,5′- Tetrakis (trifluoromethyl) oxy-4,4′-diphthalic dianhydride, 3,3 ′, 6,6′-tetrakis (trifluoromethyl) oxy-4,4′-diphthalic dianhydride, 5, 5 ', 6,6'-tetrakis (trifluoromethyl) oxy-4,4'-diphthalic dianhydride, 3,3', 5,5 ', 6,6'-hexakis (trifluoromethyl) oxy- 4,4'-diphthalic dianhydride, 3,3'-diflu Orosulfonyl-4,4′-diphthalic dianhydride, 5,5′-difluorosulfonyl-4,4′-diphthalic dianhydride, 6,6′-difluorosulfonyl-4,4′-diphthalic dianhydride 3,3 ′, 5,5 ′, 6,6′-hexafluorosulfonyl-4,4′-diphthalic dianhydride, 3,3′-bis (trifluoromethyl) sulfonyl-4,4′- Diphthalic dianhydride, 5,5′-bis (trifluoromethyl) sulfonyl-4,4′-diphthalic dianhydride, 6,6′-bis (trifluoromethyl) sulfonyl-4,4′-diphthalic acid Dianhydride, 3,3 ′, 5,5′-tetrakis (trifluoromethyl) sulfonyl-4,4′-diphthalic dianhydride, 3,3 ′, 6,6′-tetrakis (trifluoromethyl) sulfonyl -4,4'-diphthalate Dianhydride, 5,5 ′, 6,6′-tetrakis (trifluoromethyl) sulfonyl-4,4′-diphthalic dianhydride, 3,3 ′, 5,5 ′, 6,6′-hexakis ( Trifluoromethyl) sulfonyl-4,4′-diphthalic dianhydride, 3,3′-difluoro-2,2-perfluoropropylidene-4,4′-diphthalic dianhydride, 5,5′-difluoro -2,2-perfluoropropylidene-4,4'-diphthalic dianhydride, 6,6'-difluoro-2,2-perfluoropropylidene-4,4'-diphthalic dianhydride, 3, 3 ′, 5,5 ′, 6,6′-hexafluoro-2,2-perfluoropropylidene-4,4′-diphthalic dianhydride, 3,3′-bis (trifluoromethyl) -2, 2-perfluoropropylidene-4,4'-diphthalate Acid dianhydride, 5,5′-bis (trifluoromethyl) -2,2-perfluoropropylidene-4,4′-diphthalic dianhydride, 6,6′-difluoro-2,2-perfluoro Propylidene-4,4′-diphthalic dianhydride, 3,3 ′, 5,5′-tetrakis (trifluoromethyl) -2,2-perfluoropropylidene-4,4′-diphthalic dianhydride 3,3 ′, 6,6′-tetrakis (trifluoromethyl) -2,2-perfluoropropylidene-4,4′-diphthalic dianhydride, 5,5 ′, 6,6′-tetrakis ( Trifluoromethyl) -2,2-perfluoropropylidene-4,4′-diphthalic dianhydride, 3,3 ′, 5,5 ′, 6,6′-hexakis (trifluoromethyl) -2,2 -Perfluoropropylidene-4,4'-diph Talic dianhydride, 9-phenyl-9- (trifluoromethyl) xanthene-2,3,6,7-tetracarboxylic dianhydride, 9,9-bis (trifluoromethyl) xanthene-2,3 6,7-tetracarboxylic dianhydride, bicyclo [2,2,2] oct-7-ene-2,3,5,6-tetracarboxylic dianhydride, 9,9-bis [4- (3 , 4-Dicarboxy) phenyl] fluorene dianhydride, 9,9-bis [4- (2,3-dicarboxy) phenyl] fluorene dianhydride, ethylene glycol bistrimellitic dianhydride, 1,2- ( Ethylene) bis (trimellitic anhydride), 1,3- (trimethylene) bis (trimellitic anhydride), 1,4- (tetramethylene) bis (trimellitic anhydride), 1,5- (pentamethylene) bis (trimetic anhydride) Retate anhydride), 1,6- (hexamethylene) bis (trimellitic anhydride), 1,7- (heptamethylene) bis (trimellitate anhydride), 1,8- (octamethylene) bis (trimellitic anhydride), 1,9- (nonamethylene) bis (trimellitic anhydride), 1,10- (decamethylene) bis (trimellitic anhydride), 1,12- (dodecamethylene) bis (trimellitic anhydride), 1,16- (hexadeca) Methylene) bis (trimellitate anhydride), 1,18- (octadecamethylene) bis (trimellitate anhydride), and the like.

  Examples of the tricarboxylic acid anhydride include trimellitic acid anhydride and nuclear hydrogenated trimellitic acid anhydride.

  Examples of the amine component include diamines such as aliphatic diamines and aromatic diamines, and polyvalent amines such as aliphatic polyether amines, but are not limited to these amines. These amine components may be used alone or in combination.

  Examples of the diamine include one diamine nucleus diamine such as p-phenylenediamine (PPD), 1,3-diaminobenzene, 2,4-toluenediamine, 2,5-toluenediamine, and 2,6-toluenediamine. , 4′-diaminodiphenyl ether, 3,3′-diaminodiphenyl ether, diaminodiphenyl ethers such as 3,4′-diaminodiphenyl ether, 4,4′-diaminodiphenylmethane, 3,3′-dimethyl-4,4′-diaminobiphenyl 2,2′-dimethyl-4,4′-diaminobiphenyl, 2,2′-bis (trifluoromethyl) -4,4′-diaminobiphenyl, 3,3′-dimethyl-4,4′-diaminodiphenylmethane 3,3 ′, 5,5′-tetramethyl-4,4′-diaminodiphenylme , Bis (4-aminophenyl) sulfide, 4,4′-diaminobenzanilide, 3,3′-dichlorobenzidine, 3,3′-dimethylbenzidine (o-tolidine), 2,2′-dimethylbenzidine (m -Toridine), 3,3'-dimethoxybenzidine, 2,2'-dimethoxybenzidine, 3,3'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl ether, 3,3'-diamino Diphenyl sulfide, 3,4'-diaminodiphenyl sulfide, 4,4'-diaminodiphenyl sulfide, 3,3'-diaminodiphenyl sulfone, 3,4'-diaminodiphenyl sulfone, 4,4'-diaminodiphenyl sulfone, 3, 3'-diaminobenzophenone, 3,3'-diamino- , 4′-dichlorobenzophenone, 3,3′-diamino-4,4′-dimethoxybenzophenone, 3,3′-diaminodiphenylmethane, 3,4′-diaminodiphenylmethane, 4,4′-diaminodiphenylmethane, 2,2- Bis (3-aminophenyl) propane, 2,2-bis (4-aminophenyl) propane, 2,2-bis (3-aminophenyl) -1,1,1,3,3,3-hexafluoropropane, 2,2-bis (4-aminophenyl) -1,1,1,3,3,3-hexafluoropropane, 3,3′-diaminodiphenyl sulfoxide, 3,4′-diaminodiphenyl sulfoxide, 4,4 ′ -Two diamine diamines such as diaminodiphenyl sulfoxide, 3,3'-dicarboxy-4,4'-diaminodiphenylmethane 1,3-bis (3-aminophenyl) benzene, 1,3-bis (4-aminophenyl) benzene, 1,4-bis (3-aminophenyl) benzene, 1,4-bis (4-aminophenyl) ) Benzene, 1,3-bis (4-aminophenoxy) benzene, 1,4-bis (3-aminophenoxy) benzene, 1,4-bis (4-aminophenoxy) benzene, 1,3-bis (3- Aminophenoxy) -4-trifluoromethylbenzene, 3,3′-diamino-4- (4-phenyl) phenoxybenzophenone, 3,3′-diamino-4,4′-di (4-phenylphenoxy) benzophenone, 1 , 3-bis (3-aminophenyl sulfide) benzene, 1,3-bis (4-aminophenyl sulfide) benzene, 1,4-bis (4-aminophenyl) Rufido) benzene, 1,3-bis (3-aminophenylsulfone) benzene, 1,3-bis (4-aminophenylsulfone) benzene, 1,4-bis (4-aminophenylsulfone) benzene, 1,3- Bis [2- (4-aminophenyl) isopropyl] benzene, 1,4-bis [2- (3-aminophenyl) isopropyl] benzene, 1,4-bis [2- (4-aminophenyl) isopropyl] benzene, etc. Benzene nucleus of three diamines, 3,3′-bis (3-aminophenoxy) biphenyl, 3,3′-bis (4-aminophenoxy) biphenyl, 4,4′-bis (3-aminophenoxy) biphenyl, 4 , 4′-bis (4-aminophenoxy) biphenyl, bis [3- (3-aminophenoxy) phenyl] ether, bis [3- ( -Aminophenoxy) phenyl] ether, bis [4- (3-aminophenoxy) phenyl] ether, bis [4- (4-aminophenoxy) phenyl] ether, bis [3- (3-aminophenoxy) phenyl] ketone, Bis [3- (4-aminophenoxy) phenyl] ketone, bis [4- (3-aminophenoxy) phenyl] ketone, bis [4- (4-aminophenoxy) phenyl] ketone, bis [3- (3-amino Phenoxy) phenyl] sulfide, bis [3- (4-aminophenoxy) phenyl] sulfide, bis [4- (3-aminophenoxy) phenyl] sulfide, bis [4- (4-aminophenoxy) phenyl] sulfide, bis [ 3- (3-aminophenoxy) phenyl] sulfone, bis [3- (4-aminophenoxy) ) Phenyl] sulfone, bis [4- (3-aminophenoxy) phenyl] sulfone, bis [4- (4-aminophenoxy) phenyl] sulfone, bis [3- (3-aminophenoxy) phenyl] methane, bis [3 -(4-aminophenoxy) phenyl] methane, bis [4- (3-aminophenoxy) phenyl] methane, bis [4- (4-aminophenoxy) phenyl] methane, 2,2-bis [3- (3- Aminophenoxy) phenyl] propane, 2,2-bis [3- (4-aminophenoxy) phenyl] propane, 2,2-bis [4- (3-aminophenoxy) phenyl] propane, 2,2-bis [4 -(4-aminophenoxy) phenyl] propane, 2,2-bis [3- (3-aminophenoxy) phenyl] -1,1,1,3,3,3-he Safluoropropane, 2,2-bis [3- (4-aminophenoxy) phenyl] -1,1,1,3,3,3-hexafluoropropane, 2,2-bis [4- (3-aminophenoxy) ) Phenyl] -1,1,1,3,3,3-hexafluoropropane, 2,2-bis [4- (4-aminophenoxy) phenyl] -1,1,1,3,3,3-hexa Aromatic diamines such as four diamines of benzene nucleus such as fluoropropane, 1,2-diaminoethane, 1,3-diaminopropane, 1,4-diaminobutane, 1,5-diaminopentane, 1,6-diaminohexane, 1,7-diaminoheptane, 1,8-diaminooctane, 1,9-diaminononane, 1,10-diaminodecane, 1,11-diaminoundecane, 1,12-diaminododecane, 1 It includes aliphatic diamines of 2-diaminocyclohexane, etc., the aliphatic polyether amines, polyvalent amines ethylene glycol and / or propylene glycol and the like. Moreover, the amine which has a carboxyl group can also be used as follows.

  Examples of the amine having a carboxyl group include 3,5-diaminobenzoic acid, 2,5-diaminobenzoic acid, diaminobenzoic acids such as 3,4-diaminobenzoic acid, and 3,5-bis (3-aminophenoxy) benzoic acid. Aminophenoxybenzoic acids such as 3,5-bis (4-aminophenoxy) benzoic acid, 3,3′-diamino-4,4′-dicarboxybiphenyl, 4,4′-diamino-3,3′-di Carboxybiphenyl compounds such as carboxybiphenyl, 4,4′-diamino-2,2′-dicarboxybiphenyl, 4,4′-diamino-2,2 ′, 5,5′-tetracarboxybiphenyl, 3,3 ′ -Diamino-4,4'-dicarboxydiphenylmethane, 3,3'-dicarboxy-4,4'-diaminodiphenylmethane, 2,2-bis [3-amino-4-carbo Cyphenyl] propane, 2,2-bis [4-amino-3-carboxyphenyl] propane, 2,2-bis [3-amino-4-carboxyphenyl] hexafluoropropane, 4,4′-diamino-2,2 Carboxydiphenylalkanes such as carboxydiphenylmethane such as', 5,5'-tetracarboxydiphenylmethane, 3,3'-diamino-4,4'-dicarboxydiphenyl ether, 4,4'-diamino-3,3'-di Carboxydiphenyl ether compounds such as carboxydiphenyl ether, 4,4′-diamino-2,2′-dicarboxydiphenyl ether, 4,4′-diamino-2,2 ′, 5,5′-tetracarboxydiphenyl ether, 3,3′- Diamino-4,4′-dicarboxydiphenylsulfone, 4,4′-dia Mino-3,3′-dicarboxydiphenyl sulfone, 4,4′-diamino-2,2′-dicarboxydiphenyl sulfone, 4,4′-diamino-2,2 ′, 5,5′-tetracarboxydiphenyl sulfone Bis [(carboxyphenyl) phenyl] alkane compounds such as 2,2-bis [4- (4-amino-3-carboxyphenoxy) phenyl] propane, 2,2-bis [4- ( And bis [(carboxyphenoxy) phenyl] sulfone compounds such as 4-amino-3-carboxyphenoxy) phenyl] sulfone.

  In order to introduce a phenolic hydroxyl group into a polyimide resin, a method of synthesizing with a diamine having a phenolic hydroxyl group can be used. Examples of the diamine having a phenolic hydroxyl group include diaminophenols such as 2,4-diaminophenol, 3,3′-diamino-4,4′-dihydroxybiphenyl, 4,4′-diamino-3,3′-. Hydroxybiphenyl compounds such as dihydroxybiphenyl, 4,4′-diamino-2,2′-dihydroxybiphenyl, 4,4′-diamino-2,2 ′, 5,5′-tetrahydroxybiphenyl, 3,3′- Diamino-4,4′-dihydroxydiphenylmethane, 4,4′-diamino-3,3′-dihydroxydiphenylmethane, 4,4′-diamino-2,2′-dihydroxydiphenylmethane, 2,2-bis [3- Amino-4-hydroxyphenyl] propane, 2,2-bis [4-amino-3-hydroxyphenyl] propane, 2 , 2-bis [3-amino-4-hydroxyphenyl] hexafluoropropane, hydroxydiphenylalkanes such as hydroxydiphenylmethane such as 4,4′-diamino-2,2 ′, 5,5′-tetrahydroxydiphenylmethane, 3 , 3′-diamino-4,4′-dihydroxydiphenyl ether, 4,4′-diamino-3,3′-dihydroxydiphenyl ether, 4,4′-diamino-2,2′-dihydroxydiphenyl ether, 4,4′-diamino Hydroxydiphenyl ether compounds such as 2,2 ′, 5,5′-tetrahydroxydiphenyl ether, 3,3′-diamino-4,4′-dihydroxydiphenylsulfone, 4,4′-diamino-3,3′-dihydroxydiphenyl Sulfone, 4,4'-diamino-2,2'- Diphenylsulfone compounds such as hydroxydiphenylsulfone, 4,4′-diamino-2,2 ′, 5,5′-tetrahydroxydiphenylsulfone, 2,2-bis [4- (4-amino-3-hydroxyphenoxy) phenyl Bis [(hydroxyphenyl) phenyl] alkane compounds such as propane, bis (hydroxyphenoxy) biphenyl compounds such as 4,4′-bis (4-amino-3-hydroxyphenoxy) biphenyl, 2,2- Bis [(hydroxyphenoxy) phenyl] sulfone compounds such as bis [4- (4-amino-3-hydroxyphenoxy) phenyl] sulfone, 4,4′-diamino-3,3′-dihydroxydiphenylmethane, 4,4 ′ -Carboxydiphenyl such as diamino-2,2'-dihydroxydiphenylmethane Bis (hydroxyphenoxy) biphenyl compounds such as alkanes, 4,4′-diamino-2,2′-dihydroxydiphenylmethane, 4,4′-bis (4-amino-3-hydroxyphenoxy) biphenyl, 1,3 And bis (hydroxyphenoxy) benzene compounds such as bis (3-amino-4-hydroxyphenoxy) benzene and 1,3-bis (4-amino-3-hydroxyphenoxy) benzene.

  Diisocyanates such as aromatic diisocyanates and isomers and multimers, aliphatic diisocyanates, alicyclic diisocyanates and isomers thereof, and other general-purpose diisocyanates can be used as the isocyanate component. It is not limited. These isocyanate components may be used alone or in combination.

  Examples of diisocyanates include aromatic diisocyanates such as 4,4′-diphenylmethane diisocyanate, tolylene diisocyanate, naphthalene diisocyanate, xylylene diisocyanate, biphenyl diisocyanate, diphenyl sulfone diisocyanate, diphenyl ether diisocyanate, and isomers, multimers, hexamethylene diisocyanate, isophorone. Examples thereof include aliphatic diisocyanates such as diisocyanate, dicyclohexylmethane diisocyanate, and xylylene diisocyanate, alicyclic diisocyanates and isomers obtained by hydrogenation of the aromatic diisocyanate, and other general-purpose diisocyanates.

  The polyimide resin as component (A) may have an amide bond. This may be an amide bond obtained by reacting an isocyanate and a carboxylic acid, or may be caused by other reaction. Furthermore, you may have the coupling | bonding which consists of another addition and condensation.

  For the synthesis of the polyimide resin as the component (A), a publicly known and commonly used alkali-soluble polymer, oligomer or monomer having a carboxyl group and / or an acid anhydride group may be used. Resins obtained by reacting with the above amines / isocyanates alone or in combination with the above carboxylic anhydride component may also be used.

  The polyimide resin as component (A) preferably has an acid value of 20 to 200 mgKOH / g, more preferably 60 to 150 mgKOH / g in order to correspond to the alkali development step. When the acid value is 20 mgKOH / g or more, the solubility in alkali increases, the developability becomes good, and further, the degree of crosslinking with the thermosetting component after light irradiation becomes high, so that sufficient development contrast is obtained. be able to. Moreover, when this acid value is 200 mgKOH / g or less, what is called a hot fog in the PEB process after light irradiation mentioned later can be suppressed, and a process margin becomes large.

The molecular weight of the polyimide resin as component (A) is preferably 1,000 to 100,000, more preferably 2,000 to 50,000, considering developability and cured coating film characteristics.
When the molecular weight is 1,000 or more, sufficient development resistance and cured properties can be obtained after exposure and PEB. On the other hand, when the molecular weight is 100,000 or less, alkali solubility increases and developability improves.

[(B) Photobase generator]
(B) The photobase generator is a catalyst for an addition reaction between a polyimide resin having a carboxyl group and a thermosetting component when the molecular structure is changed by light irradiation such as ultraviolet light or visible light, or when the molecule is cleaved. Is a compound that produces one or more basic substances that can function as Examples of basic substances include secondary amines and tertiary amines.
Examples of photobase generators include α-aminoacetophenone compounds, oxime ester compounds, acyloxyimino groups, N-formylated aromatic amino groups, N-acylated aromatic amino groups, nitrobenzyl carbamate groups, and alkoxyoxybenzyl carbamates. And compounds having a substituent such as a group. Of these, oxime ester compounds and α-aminoacetophenone compounds are preferred. As the α-aminoacetophenone compound, those having two or more nitrogen atoms are particularly preferable.

  Other photobase generators include WPBG-018 (trade name: 9-anthrylmethylN, N'-diethylcarbamate), WPBG-027 (trade name: (E) -1- [3- (2-hydroxyphenyl) -2-propenoyl ] piperidine), WPBG-082 (trade name: guanidinium2- (3-benzoylphenyl) propionate), WPBG-140 (trade name: 1- (anthraquinon-2-yl) ethyl imidazolecarboxylate), and the like can also be used.

  The α-aminoacetophenone compound has a benzoin ether bond in the molecule, and when irradiated with light, cleavage occurs in the molecule to produce a basic substance (amine) that exhibits a curing catalytic action. Specific examples of the α-aminoacetophenone compound include (4-morpholinobenzoyl) -1-benzyl-1-dimethylaminopropane (Irgacure 369, trade name, manufactured by BASF Japan Ltd.) and 4- (methylthiobenzoyl) -1-methyl. -1-morpholinoethane (Irgacure 907, trade name, manufactured by BASF Japan Ltd.), 2- (dimethylamino) -2-[(4-methylphenyl) methyl] -1- [4- (4-morpholinyl) phenyl]- A commercially available compound such as 1-butanone (Irgacure 379, trade name, manufactured by BASF Japan Ltd.) or a solution thereof can be used.

（式中、Ｒ^１は、水素原子、無置換または炭素数１〜６のアルキル基、フェニル基もしくはハロゲン原子で置換されたフェニル基、無置換または１個以上の水酸基で置換された炭素数１〜２０のアルキル基、１個以上の酸素原子で中断された該アルキル基、無置換または炭素数１〜６のアルキル基もしくはフェニル基で置換された炭素数５〜８のシクロアルキル基、無置換または炭素数１〜６のアルキル基もしくはフェニル基で置換された炭素数２〜２０のアルカノイル基又はベンゾイル基を表し、
Ｒ^２は、無置換または炭素数１〜６のアルキル基、フェニル基もしくはハロゲン原子で置換されたフェニル基、無置換または１個以上の水酸基で置換された炭素数１〜２０のアルキル基、１個以上の酸素原子で中断された該アルキル基、無置換または炭素数１〜６のアルキル基もしくはフェニル基で置換された炭素数５〜８のシクロアルキル基、無置換または炭素数１〜６のアルキル基もしくはフェニル基で置換された炭素数２〜２０のアルカノイル基又はベンゾイル基を表す。） Any oxime ester compound can be used as long as it is a compound that generates a basic substance by light irradiation. As such an oxime ester compound, an oxime ester photobase generator having a group represented by the following general formula (4) is preferable.

(Wherein R ¹ is a hydrogen atom, an unsubstituted or alkyl group having 1 to 6 carbon atoms, a phenyl group substituted with a phenyl group or a halogen atom, unsubstituted or substituted with one or more hydroxyl groups. -20 alkyl group, the alkyl group interrupted by one or more oxygen atoms, unsubstituted, C1-C6 alkyl group or phenyl group substituted with C5-C8 cycloalkyl group, unsubstituted Or an alkanoyl group having 2 to 20 carbon atoms or a benzoyl group substituted with an alkyl group having 1 to 6 carbon atoms or a phenyl group,
R ² represents an unsubstituted or alkyl group having 1 to 6 carbon atoms, a phenyl group substituted with a phenyl group or a halogen atom, an unsubstituted or alkyl group having 1 to 20 carbon atoms substituted with one or more hydroxyl groups, The alkyl group interrupted by one or more oxygen atoms, unsubstituted or a cycloalkyl group having 5 to 8 carbon atoms substituted by an alkyl group having 1 to 6 carbon atoms or a phenyl group, unsubstituted or having 1 to 6 carbon atoms An alkanoyl group having 2 to 20 carbon atoms or a benzoyl group substituted with an alkyl group or a phenyl group is represented. )

  Examples of commercially available oxime ester photobase generators include CGI-325, Irgacure OXE01, Irgacure OXE02 manufactured by BASF Japan, N-1919, NCI-831 manufactured by Adeka. Moreover, the compound which has two oxime ester groups in the molecule | numerator described in the patent 4344400 gazette can also be used suitably.

  In addition, JP-A-2004-359639, JP-A-2005-097141, JP-A-2005-220097, JP-A-2006-160634, JP-A-2008-094770, JP-A-2008-509967, Specific examples include carbazole oxime ester compounds described in JP2009-040762A and JP2011-80036A.

  Such a photobase generator may be used individually by 1 type, and may be used in combination of 2 or more type. The blending amount of the photobase generator in the alkali development type thermosetting resin composition is preferably 0.1 to 40 parts by mass, more preferably 0.1 to 30 parts by mass with respect to 100 parts by mass of the thermosetting component. Part by mass. In the case of 0.1 parts by mass or more, the development resistance contrast of the light irradiated part / non-irradiated part can be favorably obtained. Moreover, in 40 mass parts or less, hardened | cured material characteristic improves.

[(C) Thermosetting component]
(C) The thermosetting component has a functional group capable of addition reaction with a carboxyl group or a phenolic hydroxyl group by heat. As the thermosetting component, for example, a compound having a cyclic (thio) ether group is preferable, and examples thereof include an epoxy resin and a polyfunctional oxetane compound.

  The epoxy resin is a resin having an epoxy group, and any known one can be used. Examples thereof include a bifunctional epoxy resin having two epoxy groups in the molecule, and a polyfunctional epoxy resin having many epoxy groups in the molecule. In addition, a hydrogenated bifunctional epoxy compound may be used.

  Examples of the epoxy compound include bisphenol A type epoxy resin, brominated epoxy resin, novolac type epoxy resin, bisphenol F type epoxy resin, hydrogenated bisphenol A type epoxy resin, glycidylamine type epoxy resin, hydantoin type epoxy resin, and alicyclic type. Epoxy resin, trihydroxyphenylmethane type epoxy resin, bixylenol type or biphenol type epoxy resin or a mixture thereof; bisphenol S type epoxy resin, bisphenol A novolac type epoxy resin, tetraphenylolethane type epoxy resin, heterocyclic epoxy resin , Diglycidyl phthalate resin, tetraglycidyl xylenoyl ethane resin, naphthalene group-containing epoxy resin, epoxy resin having dicyclopentadiene skeleton, glycidyl methacrylate Relate copolymerization system epoxy resins, copolymerized epoxy resins of cyclohexylmaleimide and glycidyl methacrylate, and a CTBN modified epoxy resin.

  Other liquid bifunctional epoxy resins include vinylcyclohexene diepoxide, (3 ′, 4′-epoxycyclohexylmethyl) -3,4-epoxycyclohexanecarboxylate, and (3 ′, 4′-epoxy-6′-methyl). And alicyclic epoxy resins such as (cyclohexylmethyl) -3,4-epoxy-6-methylcyclohexanecarboxylate. These epoxy resins may be used individually by 1 type, and may use 2 or more types together.

  In addition, you may mix | blend well-known and usual compounds, such as a maleimide compound, a block isocyanate compound, an amino resin, a benzoxazine resin, a carbodiimide resin, a cyclocarbonate compound, an episulfide resin, as a thermosetting component (C).

  (C) As a compounding quantity of a thermosetting component, equivalence ratio (a carboxyl group: thermoreactive groups, such as an epoxy group) with the polyimide resin which is (A) component is 1: 0.1-1: 10. Is preferred. By setting the blending ratio in such a range, development becomes favorable and a fine pattern can be easily formed. The equivalent ratio is more preferably 1: 0.2 to 1: 5.

[(D) Flame retardant]
The photosensitive thermosetting resin composition of the present invention contains a reactive compound as a flame retardant. As the flame retardant having such reactivity, for example, phosphorus-containing compounds can be mentioned, and one kind may be used alone, or two or more kinds may be used in combination.

（式中、Ｒ^５、Ｒ^６及びＲ^７は、それぞれ独立に、ハロゲン原子以外の置換基を示す。） Examples of the phosphorus-containing compound having reactivity include those known as organophosphorus flame retardants. Among such organic phosphorus flame retardants, preferred are phosphoric acid esters and condensed phosphoric acid esters, phosphorus element-containing (meth) acrylates, phosphorus compounds having a carboxyl group, phosphorus-containing compounds having a phenolic hydroxyl group, The compound etc. which are represented with general formula (I) are mentioned.

(In the formula, R ⁵ , R ⁶ and R ⁷ each independently represent a substituent other than a halogen atom.)

The phosphorus element-containing (meth) acrylate is preferably a compound having a phosphorus element and having a plurality of (meth) acryloyl groups in the molecule. Specifically, R ⁵ in the above general formula (I) and Examples include compounds in which R ⁶ is a hydrogen atom and R ⁷ is a (meth) acrylate derivative. Generally, it can be synthesized by a Michael addition reaction between 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide and a known and commonly used polyfunctional (meth) acrylate monomer.

In the photosensitive thermosetting resin composition of the present invention, a more preferable flame retardant is a phosphorus-containing compound having a phenolic hydroxyl group from the viewpoints of workability and handleability of the resin composition as described above. Such phosphorus-containing compounds have the advantages of high hydrophobicity and heat resistance, no deterioration in electrical properties due to hydrolysis, and high solder heat resistance. Further, as an appropriate combination, when an epoxy resin is used among thermosetting resins, there is an advantage that it does not bleed out after curing because it reacts with the epoxy group and is taken into the network. Among the phosphorus-containing compounds having a phenolic hydroxyl group, in the general formula (I), R ⁵ and R ⁶ are hydrogen atoms or alkyl groups having 1 to 4 carbon atoms, and R ⁷ is 2 , 5-dihydroxyphenyl group, or 3,5-di-t-butyl-4-hydroxyphenyl group, but is not limited thereto.

  Commercially available products of the phosphorus-containing compound represented by the general formula (I) include HCA, SANKO-220, M-ESTER, HCA-HQ (all are trade names of Sankosha), and the like.

Further, a phosphorus-containing compound that is an oligomer or polymer having a phenolic hydroxyl group is preferable because it is less likely to bend due to the influence of an alkyl chain and has a large molecular weight, so that there is no bleeding out after curing.
Moreover, the phosphorus element containing dicarboxylic acid represented by the following general formula (II) or its anhydride can also be used as an oligomer which has carboxylic acid.

Examples of the hydrocarbon group having 1 to 6 carbon atoms represented by R ⁸ and R ⁹ in the general formula (II) include an alkyl group having 1 to 6 carbon atoms and an alkenyl having 1 to 6 carbon atoms. Group, cycloalkyl group and phenyl group. Examples of the alkyl group having 1 to 6 carbon atoms include methyl group, ethyl group, propyl group, isopropyl group, butyl group, secondary butyl group, tertiary butyl group, isobutyl group, pentyl group, isopentyl group, and tertiary pentyl group. Examples of the alkenyl group having 1 to 6 carbon atoms such as hexyl group include vinyl group, allyl group, 3-butenyl group, isobutenyl group, 4-pentenyl group, and 5-hexenyl group. The hydrocarbon group having 1 to 6 carbon atoms may be branched or substituted.

  Examples of the phosphorus element-containing dicarboxylic acid or anhydride thereof include compounds obtained by reacting 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide with itaconic acid and anhydrides thereof. Thing etc. are mentioned.

  The reactive phosphorus-containing compound may be used alone or in combination of two or more. In order to obtain a good flame retardant effect, and to obtain the bending resistance and insulation reliability of the cured product, the compounding amount of the reactive phosphorus-containing compound is the phosphorus content in the photosensitive thermosetting resin composition. The content of is preferably 0.01 to 3.0 mass%, more preferably 0.01 to 2.5 mass%.

(Resin having a phenolic hydroxyl group)
The photosensitive thermosetting resin composition of the present invention preferably contains a resin having a phenolic hydroxyl group. When a resin having a phenolic hydroxyl group is present, the time until the alkali resistance is obtained by the addition reaction at the same heating temperature at the time of the heat curing reaction after exposure (at the time of the following PEB process) as compared with the case where it does not exist. Can be long. Moreover, the selection range of the heating temperature at the time of thermosetting reaction (at the time of the following PEB process) can be expanded. From these things, the workability | operativity and handleability of a resin composition improve. It is also possible to suppress the occurrence of so-called fogging in which the unexposed portion becomes resistant to alkali.
The resin having a phenolic hydroxyl group is not particularly limited as long as it has a phenolic hydroxyl group in the main chain or side chain, that is, a hydroxyl group bonded to a benzene ring. Similarly to the carboxyl group, the phenolic hydroxyl group can undergo an addition reaction with the thermosetting component.

As the resin having a phenolic hydroxyl group, one having an imide ring is preferable. Examples of the imide ring are the same as those described above. As the resin having an imide ring and a phenolic hydroxyl group, for example, a polyimide resin synthesized using a diamine having a phenolic hydroxyl group with respect to the carboxylic acid anhydride as described above is preferable.
The molecular weight of the resin having a phenolic hydroxyl group is preferably a mass average molecular weight of 1,000 to 100,000, more preferably 2,000 to 50, in consideration of developability after exposure and PEB, development resistance and cured coating film properties. 000 is more preferable.

(Polymer resin)
The photosensitive thermosetting resin composition of the present invention can be blended with conventionally known polymer resins for the purpose of improving the flexibility and dryness of the touch of the resulting cured product. Examples of the polymer resin include cellulose, polyester, phenoxy resin, polyvinyl acetal, polyvinyl butyral, polyamide, polyamideimide binder polymer, block copolymer, elastomer and the like. The above polymer resins may be used alone or in combination of two or more.

(Inorganic filler)
An inorganic filler can be blended in the photosensitive thermosetting resin composition of the present invention. An inorganic filler is used in order to suppress the curing shrinkage of the cured product of the photosensitive thermosetting resin composition and to improve properties such as adhesion and hardness. Examples of the inorganic filler include barium sulfate, amorphous silica, fused silica, spherical silica, talc, clay, magnesium carbonate, calcium carbonate, aluminum oxide, aluminum hydroxide, silicon nitride, aluminum nitride, boron nitride, and Neuburg Examples include rich earth. The said inorganic filler may be used individually by 1 type, and may use 2 or more types together.

(Coloring agent)
Furthermore, a coloring agent can be mix | blended with the photosensitive thermosetting resin composition of this invention. As the colorant, conventionally known colorants such as red, blue, green, yellow, white, and black can be used, and any of pigments, dyes, and pigments may be used.

(Organic solvent)
In the photosensitive thermosetting resin composition of the present invention, an organic solvent can be used for preparing the resin composition and adjusting the viscosity for application to a substrate or a carrier film.
Examples of such organic solvents include ketones, aromatic hydrocarbons, glycol ethers, glycol ether acetates, esters, alcohols, aliphatic hydrocarbons, petroleum solvents, and the like. Such an organic solvent may be used individually by 1 type, and may be used as a 2 or more types of mixture.

(Other optional ingredients)
If necessary, the photosensitive thermosetting resin composition of the present invention may further contain components such as a mercapto compound, an adhesion promoter, an antioxidant, and an ultraviolet absorber. As these, those known in the field of electronic materials can be used. The photosensitive thermosetting resin composition includes a known and commonly used thickener such as finely divided silica, hydrotalcite, organic bentonite, and montmorillonite, an antifoaming agent such as silicone, fluorine, and polymer. // Known additives such as a leveling agent, a silane coupling agent, and a rust preventive agent can be blended.

[Dry film]
The dry film of the present invention is characterized by having a resin layer comprising the photosensitive thermosetting resin composition of the present invention.
In forming a dry film, for example, the photosensitive thermosetting resin composition of the present invention is diluted with an organic solvent to adjust to an appropriate viscosity, and a uniform thickness is formed on the carrier film by a known method such as a comma coater. Apply. Thereafter, drying is usually performed at a temperature of 50 to 130 ° C. for 1 to 30 minutes to form a resin layer on the carrier film.

  A plastic film is used as the carrier film. Although there is no restriction | limiting in particular about the thickness of a carrier film, Generally, it selects suitably in the range of 10-150 micrometers. After forming the resin layer on the carrier film, a peelable cover film may be further laminated on the surface of the resin layer.

[Flexible printed wiring board and manufacturing method thereof]
The flexible printed wiring board of the present invention is characterized by having a cured product composed of a photosensitive thermosetting resin composition or a resin layer of a dry film.
The method for producing a flexible printed wiring board of the present invention includes a step of forming a resin layer made of a photosensitive thermosetting resin composition on a flexible printed wiring board, a step of irradiating the resin layer with light in a pattern, and a resin layer. A step of heating, and a step of alkali-developing the resin layer to form at least one of a coverlay and a solder resist.

[Resin layer forming step]
In this step, at least one resin layer made of an alkali development type thermosetting resin composition is formed on the flexible printed wiring board.
Examples of the method for forming the resin layer include a coating method and a laminating method.
In the case of the application method, the alkali development type thermosetting resin composition is applied onto the flexible printed wiring board by a method such as screen printing and dried to form a resin layer.
In the case of the laminating method, first, the alkali development type thermosetting resin composition is diluted with an organic solvent to adjust to an appropriate viscosity, applied onto a carrier film, and dried to prepare a dry film having a resin layer. Next, after bonding together so that a resin layer may contact a flexible printed wiring board with a laminator etc., a carrier film is peeled.

  Moreover, another layer can be interposed between the resin layer and the flexible printed wiring board. The other layer is preferably made of an alkali development type photosensitive resin composition. As the alkali development type photosensitive resin composition, a known composition can be used. For example, a carboxyl group-containing resin or a carboxyl group-containing photosensitive resin conventionally used as a solder resist composition, and an ethylenic resin A photocurable thermosetting resin composition containing a compound having an unsaturated bond, a photopolymerization initiator, and a thermoreactive compound, a carboxyl group-containing resin, a photobase generator, and a thermoreactive compound A photosensitive thermosetting resin composition or the like can be used. Thus, by setting it as the laminated structure including another layer, the hardened | cured material which was further excellent in impact resistance and flexibility can be obtained. The interface between the layers of the laminated structure may be familiar.

[Light irradiation process]
This step activates the photobase generator contained in the resin layer by light irradiation in a negative pattern to cure the light irradiation part. In this step, the photobase generator is destabilized by the base generated in the light irradiation part, and the base is chemically proliferated, whereby the resin layer can be sufficiently cured to the deep part.

As the light irradiator, a direct writer, a light irradiator equipped with a metal halide lamp, or the like can be used. The patterned light irradiation mask is a negative mask.
As the active energy ray used for light irradiation, it is preferable to use laser light or scattered light having a maximum wavelength in the range of 350 to 450 nm. By setting the maximum wavelength within this range, the photobase generator can be activated efficiently. If a laser beam in this range is used, either a gas laser or a solid laser may be used. Moreover, although the light irradiation amount changes with film thicknesses etc., it can generally be set as 100-1500 mJ / cm < ² >.

[Heating process]
In this step, after the light irradiation, the light irradiation part is cured by heating the resin layer. By this process, it is possible to cure to a deep part by the base generated in the light irradiation process. The heating temperature is, for example, 80 to 140 ° C. The heating time is, for example, 10 to 100 minutes.
Since the curing of the photosensitive thermosetting resin composition in the present invention is, for example, a ring-opening reaction of an epoxy resin by a thermal reaction, it can suppress distortion and curing shrinkage compared to the case where curing proceeds by a photoradical reaction. it can.

[Development process]
In the development step, the unirradiated portion is removed by alkali development to form a negative patterned insulating film, particularly a coverlay and a solder resist.
The developing method can be a known method such as dipping. Moreover, as a developing solution, a well-known and usual thing can be used, for example, alkaline aqueous solutions, such as potassium hydroxide, amines, imidazoles, tetramethylammonium hydroxide aqueous solution (TMAH), or these liquid mixture are used. Can do.
Note that the insulating film may be further irradiated with light after the development step. For example, you may heat at 150 degreeC or more.

  Next, an example of a method for producing the flexible printed wiring board of the present invention from the photosensitive thermosetting resin composition of the present invention will be described based on the process diagram of FIG. FIG. 1 shows a case where the resin layer has a laminated structure, but it may be composed of only one layer.

In the laminating process of FIG. 1, a laminated structure composed of the resin layer 3 and the resin layer 4 is formed on the flexible printed wiring substrate 1 on which the copper circuit 2 is formed.
The resin layer 3 is made of an alkali development type photosensitive resin composition containing a carboxyl group-containing resin or the like.
The resin layer 4 is formed on the resin layer 3 and is a photosensitive heat containing a polyimide resin having one or more imide rings and one or more carboxyl groups in one molecule, a photobase generator, and a thermosetting component. It consists of a curable resin composition.

  The light irradiation process of FIG. 1 activates the photobase generator contained in the photosensitive thermosetting resin composition by disposing a mask 5 on the resin layer 4 and irradiating light in a negative pattern. This is a step of curing the light irradiation part. The heating process of FIG. 1 is a process (PEB process) of curing the light irradiation part by heating the resin layer after the light irradiation process. The development process in FIG. 1 is a process in which an unirradiated portion is removed by developing with an alkaline aqueous solution, and a negative pattern layer is formed.

  In addition, the 2nd light irradiation process of FIG. 1 is a process for activating the remaining photobase generator as needed, and generating a base, and a thermosetting process is a pattern layer as needed. This is a process for sufficient heat curing.

  EXAMPLES Hereinafter, although an Example and a comparative example demonstrate this invention further in detail, this invention is not restrict | limited by these Examples and a comparative example.

<Synthesis example of polyimide resin solution having imide ring and carboxyl group>
12.5 g of 3,5-diaminobenzoic acid, 2,2′-bis [4- (4-aminophenoxy) was added to a separable three-necked flask equipped with a stirrer, a nitrogen inlet tube, a fractional ring, and a cooling ring. Phenyl] propane (8.2 g), NMP (30 g), γ-butyrolactone (30 g), 4,4′-oxydiphthalic anhydride (27.9 g) and trimellitic anhydride (3.8 g) were added. For 4 hours. Next, 20 g of toluene was added and stirred for 4 hours while distilling off toluene and water at a silicon bath temperature of 180 ° C. and 150 rpm to obtain a polyimide resin solution (PI-1) having an imide ring and a carboxyl group.
The acid value of the obtained resin (solid content) was 85 mgKOH / g, and the weight average molecular weight (Mw) was 10,000.

<Synthesis example of polyimide resin solution having imide ring, phenolic hydroxyl group, carboxyl group>
To a separable three-necked flask equipped with a stirrer, a nitrogen introduction tube, a fractionation ring, and a cooling ring, 22.4 g of 3,3′-diamino-4,4′-dihydroxydiphenylsulfone, 2,2′-bis [4 -(4-aminophenoxy) phenyl] propane 8.2 g, NMP 30 g, γ-butyrolactone 30 g, 4,4′-oxydiphthalic anhydride 27.9 g, trimellitic anhydride 3.8 g, The mixture was stirred at room temperature and 100 rpm for 4 hours under a nitrogen atmosphere. Next, 20 g of toluene was added and stirred for 4 hours while distilling off toluene and water at a silicon bath temperature of 180 ° C. and 150 rpm to obtain an alkali-soluble resin solution (PI-2) having an imide ring.
The acid value of the obtained resin (solid content) was 18 mgKOH / g, Mw was 10,000, and the hydroxyl group equivalent was 390.

<Preparation of photosensitive thermosetting resin composition>
In accordance with the formulation shown in Table 1 below, the materials described in the examples were respectively mixed, preliminarily mixed with a stirrer, and then kneaded with a three-roll mill to prepare a photosensitive thermosetting resin composition. The values in the table are parts by mass unless otherwise specified.

<Insulation reliability>
The compositions of the above Examples and Comparative Examples were applied to the entire surface of a polyimide substrate (Espanex manufactured by Nippon Steel Chemical Co., Ltd.) with L / S = 50/50 μm by screen printing, dried at 80 ° C. for 30 minutes, and room temperature. It was left to cool. The obtained substrate is exposed to a resist pattern with an optimal exposure amount using an exposure apparatus (HMW-680-GW20) equipped with a metal halide lamp, and a 1 wt% Na ₂ CO ₃ aqueous solution at 30 ° C. is sprayed at a pressure of 0.2 MPa. Development was performed for 60 seconds to obtain a resist pattern, and this substrate was cured by heating at 150 ° C. for 60 minutes. A bias voltage of DC 50 V was applied to the obtained evaluation substrate, and 85 ° C., 85% R.D. H. The resistance value was confirmed by continuous measurement in a constant temperature and humidity chamber. The judgment criteria are as follows.
○: No occurrence of short circuit and discoloration of copper foil after 1000 hours.
Δ: No short circuit occurred after 1000 hours, but there was discoloration of the copper foil.
×: Short circuit occurred within 1000 hours.

<Low warpage>
A sample prepared in the same manner as the sample for evaluation of flexibility (folding resistance) was cut into 50 mm × 50 mm □, and the average value was obtained by measuring four-angle warpage, and evaluated according to the following criteria.
○: The warp is less than 4 mm.
(Triangle | delta): The curvature is 4 mm or more and less than 8 mm.
X: The warp is 8 mm or more.

<Flame retardance>
The composition of each of the above Examples and Comparative Examples was applied on the entire surface by screen printing onto a polyimide film having a thickness of 25 μm and a thickness of 12.5 μm (manufactured by Toray DuPont, Kapton 100H (25 μm), Kapton 50H (12.5 μm)). It dried at 30 degreeC for 30 minutes, and stood to cool to room temperature. Further, the entire back surface was similarly applied by screen printing, dried at 80 ° C. for 30 minutes, and allowed to cool to room temperature to obtain a double-side coated substrate. The obtained double-sided substrate is exposed to the entire surface of the solder resist with an optimum exposure amount using an exposure apparatus (HMW-680-GW20) equipped with a metal halide lamp, and a 1 wt% Na ₂ CO ₃ aqueous solution at 30 ° C. is sprayed at a pressure of 2 kg / cm ^2. Development was performed for 60 seconds under the above conditions, and thermosetting was performed at 150 ° C. for 60 minutes to obtain an evaluation sample. This flame retardant evaluation sample was subjected to a thin material vertical combustion test based on the UL94 standard. In the evaluation, the flame retardant test pass was indicated as “◯” and the failure was indicated as “X”.

<Flexibility (breaking resistance)>
The compositions of the above Examples and Comparative Examples were applied to the entire surface of a 25 μm thick polyimide film (Kapton 100H manufactured by Toray DuPont) by screen printing, dried at 80 ° C. for 30 minutes, and allowed to cool to room temperature. The obtained substrate is exposed to a resist pattern with an optimal exposure amount using an exposure apparatus (HMW-680-GW20) equipped with a metal halide lamp, and a 1 wt% Na ₂ CO ₃ aqueous solution at 30 ° C. is sprayed at a pressure of 0.2 MPa. Development was performed for 60 seconds to obtain a resist pattern, and this substrate was cured by heating at 150 ° C. for 60 minutes.
The obtained evaluation substrate was subjected to 180 ° folding by goblet folding several times, and the occurrence of cracks in the coating film at that time was observed visually and with a 200-fold optical microscope until cracks were generated. The number of bendings was measured and evaluated according to the following criteria.
A: The number of times of bending is 6 times or more.
○: The number of bending is 4 to 5 times.
(Triangle | delta): The frequency | count of bending is 2-3 times.
X: The number of times of bending is 0 to 1 times.
The results of the above evaluation tests are summarized in Table 1.

※１ 上記合成例に従い合成したイミド環及びカルボキシル基を有するポリイミド樹脂溶液である。
※２ 上記合成例に従い合成したイミド環、フェノール性水酸基、カルボキシル基を有するポリイミド樹脂溶液である。
※３ 三菱化学社製 Ｅ８２８
※４ ＢＡＳＦ社製 イルガキュアＯＸＥ−０２
※５ 和光純薬社製 ＷＰＲＧ−０２７
※６ クラリアント社製 エクソリットＯＰ９３５ ホスフィン酸金属塩
※７ 三光社製 ＨＣＡ−ＨＱ
※８ 明和化成社製 水酸基価２８４、軟化点100℃のフェノール性水酸基を有する難燃剤

* 1 A polyimide resin solution having an imide ring and a carboxyl group synthesized according to the above synthesis example.
* 2 A polyimide resin solution having an imide ring, a phenolic hydroxyl group and a carboxyl group synthesized according to the above synthesis example.
* 3 E828 manufactured by Mitsubishi Chemical Corporation
* 4 Irgacure OXE-02 manufactured by BASF
* 5 WPRG-027 manufactured by Wako Pure Chemical Industries, Ltd.
* 6 Clariant Exolit OP935 Phosphinic acid metal salt * 7 Sanko HCA-HQ
* 8 A flame retardant having a hydroxyl value of 284 and a phenolic hydroxyl group with a softening point of 100 ° C manufactured by Meiwa Kasei Co., Ltd.

  As apparent from Table 1 above, the resin compositions of Examples 1 to 4 according to the present invention have good flame retardancy despite the small amount of flame retardant, insulation reliability, and low warpage. Excellent in resistance and folding resistance. On the other hand, the comparative example 1 which does not mix | blend a flame retardant is inferior in a flame retardance, and in addition to the (A)-(C) component of this invention, a large amount of the flame retardant which does not have reactivity. In Comparative Example 2 included in the above, flame retardancy was good, but insulation reliability was poor and low warpage was poor.

DESCRIPTION OF SYMBOLS 1 Flexible printed wiring board 2 Copper circuit 3 Resin layer 4 Resin layer 5 Mask

Claims (7)

(A) a polyimide resin having an imide ring and a carboxyl group,
(B) a photobase generator (C) a thermosetting component, and
(D) Flame retardant
Containing substantially no (meth) acrylate monomer,
Ri compound der wherein the (D) a flame retardant having reactivity with the (C) thermosetting component,
The (B) photobase generator is activated by light irradiation, the (A) the polyimide resin having a carboxyl group and the (C) thermosetting component are subjected to a heat addition reaction using the generated base as a catalyst, and fine by alkali development. A photosensitive thermosetting resin composition characterized in that it is used for applications that can be processed (here, (A) the imide ring and the carboxyl group are not substantially contained in (meth) acrylate monomer. The said (meth) acrylate monomer represents that it is 10 mass parts or less with respect to 100 mass parts of polyimide resin which has.   The photosensitive thermosetting resin composition according to claim 1, wherein the flame retardant (D) is a phosphorus-containing compound having a phenolic hydroxyl group.   The photosensitive thermosetting resin composition according to claim 1 or 2, wherein the (A) polyimide resin having an imide ring and a carboxyl group has a phenolic hydroxyl group.   The photosensitive thermosetting resin composition according to claim 1, wherein the thermosetting component (C) is a cyclic ether compound.   It is for flexible wiring boards, The photosensitive thermosetting resin composition as described in any one of Claims 1-4.   It has a resin layer which consists of a photosensitive thermosetting resin composition as described in any one of Claims 1-5, The dry film characterized by the above-mentioned.   A printed wiring board comprising the photosensitive thermosetting resin composition according to claim 1 or a cured product formed using the dry film according to claim 6.

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