JP6549848B2 - Laminated structure - Google Patents

Description

  The present invention relates to a laminated structure, and more particularly to a laminated structure useful as an insulating film of a flexible printed wiring board, a dry film and a flexible printed wiring board.

  2. Description of the Related Art In recent years, the downsizing of electronic devices by the spread of smartphones and tablet terminals has made it necessary to reduce the space of circuit boards. Therefore, the flexible print which can be bent and stored is expanding the application of the wiring board, and the flexible printed wiring board is also required to have higher reliability than ever.

  On the other hand, at present, as an insulating film for securing the insulation reliability of a flexible printed wiring board, a cover based on polyimide excellent in mechanical characteristics such as heat resistance and flexibility in a bent portion (bent portion) There is a hybrid process using a photosensitive resin composition that is excellent in electrical insulation and solder heat resistance, etc., and capable of microfabrication in the mounting portion (non-bending portion) using a ray (for example, see Patent Documents 1 and 2). It is widely adopted.

  That is, a coverlay based on polyimide excellent in mechanical properties such as heat resistance and flexibility is not suitable for fine wiring because it requires processing by die punching. Therefore, it has been necessary to partially use an alkali-developable photosensitive resin composition (solder resist) which can be processed by photolithography in a chip mounting portion where fine wiring is required.

Japanese Patent Application Laid-Open No. 62-263692 Japanese Patent Application Laid-Open No. 63-110224

  As described above, in the manufacturing process of the flexible printed wiring board, there is no choice but to adopt a mixed process of the process of bonding the cover lay and the process of forming the solder resist, and there was a problem of inferiority in cost performance and workability. .

  On the other hand, application of an insulating film as a solder resist or an insulating film as a coverlay to both the solder resist and the coverlay of a flexible printed wiring board has been studied, but both performance requirements can be sufficiently satisfied. The material has not been put to practical use yet. In particular, in a flexible printed wiring board, durability against bending is one of the most important characteristics, and therefore, a material that is applicable as a solder resist and a cover lay of a flexible printed wiring board and has excellent durability against bending The realization of was required.

  Therefore, an object of the present invention is to provide a structure that satisfies the required performance as an insulating film of a flexible printed wiring board and is also suitable for a batch formation process of a bent portion and a mounting portion, and a cured product thereof It is to provide a flexible printed wiring board having as a protective film, for example, a cover lay or a solder resist.

  As a result of intensive investigations by the present inventors, it is possible to form a structure by laminating an adhesive layer having alkali developability and a protective layer laminated on a flexible printed wiring board via this adhesive layer, and By making elongation rate into a predetermined range, it finds out that the above-mentioned subject can be solved and came to complete the present invention.

  That is, the present invention is a laminated structure comprising an adhesive layer (A) comprising an alkali-developable resin composition, and a protective layer (B) laminated to a flexible printed wiring board via the adhesive layer (A). And the elongation at room temperature of the protective layer (B) as a cured film is 2.5% or more.

  In the laminated structure of the present invention, it is preferable that both the adhesive layer (A) and the protective layer (B) can be patterned by light irradiation. Further, in the laminated structure of the present invention, the protective layer (B) is preferably made of a resin composition containing an alkali-soluble resin having an imide ring or an imide precursor skeleton. The laminated structure of the present invention can be suitably used for at least one of a bent portion and a non-bent portion of a flexible printed wiring board, and specifically, a cover lay of a flexible printed wiring board, a solder resist, and an interlayer It is useful to use at least any one application of the insulating material.

  The dry film of the present invention is characterized in that at least one surface of the above-mentioned laminated structure of the present invention is supported or protected by a film.

Furthermore, in the flexible printed wiring board of the present invention, the layer of the laminated structure of the present invention is directly formed on a flexible printed wiring substrate, or the layer of the laminated structure is formed via the dry film of the present invention. And patterning by irradiation of light, and an insulating film formed by collectively forming a pattern with a developing solution.
In the present invention, "pattern" means a cured product in a pattern, that is, an insulating film.

  According to the present invention, a laminated structure, a dry film, and a flexible printed wiring board are realized that satisfy the required performance of the flexible printed wiring board as an insulating film and are also suitable for the batch formation process of the bent portion and the mounting portion. It became possible.

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 with reference to the drawings.
(Laminated structure)
The laminated structure of the present invention comprises an adhesive layer (A) made of an alkali-developable resin composition, and a protective layer (B) laminated to a flexible printed wiring board via the adhesive layer (A), It is characterized in that the elongation at room temperature as a cured film of the protective layer (B) is 2.5% or more.

  In a flexible printed wiring board, particularly for a material used for a bent portion, it is necessary to have sufficient elongation, and for example, as a cured film, it is required to have an elongation of about 20% at room temperature. On the other hand, in the present invention, as a material applied to a flexible printed wiring board, a protective layer is formed by using a laminated structure in which an adhesive layer (A) and a protective layer (B) are laminated. (B) As the single elongation rate, if it has a low value of about 2.5% or more compared to the case of using a single layer structure, sufficient performance for applying to the bent portion is obtained. It is found that it can be obtained.

(Protective layer (B))
The protective layer (B) needs to have an elongation at room temperature of 2.5% or more as a cured film, preferably 4.0% or more, and the higher, the more preferable. By setting the elongation percentage of the protective layer (B) to 2.5% or more, when applied to the bent portion of the flexible printed wiring board, the bending can be favorably followed, and defects such as cracking may occur. Absent.

  The protective layer (B) may be composed of any composition as long as the cured film has an elongation of 2.5% or more at room temperature, for example, a solder resist composition conventionally Group-containing resin or carboxyl group-containing photosensitive resin, a compound having an ethylenically unsaturated bond, a photocurable thermosetting resin composition containing a photopolymerization initiator and a thermally reactive compound, or carboxyl used A photosensitive thermosetting resin composition containing a group-containing resin, a photobase generator and a thermally reactive compound can be used.

  Among them, the protective layer (B) is preferably made of a resin composition containing an alkali-soluble resin having an imide ring or an imide precursor skeleton.

  In the present invention, the alkali-soluble resin having an imide ring or an imide precursor skeleton is one having an alkali-soluble group such as a carboxyl group or an acid anhydride group, and an imide ring or an imide precursor skeleton. For introducing the imide ring or imide precursor skeleton into the alkali-soluble resin, known and commonly used techniques can be used. For example, there may be mentioned resins obtained by reacting a carboxylic anhydride component with either or both of an amine component and an isocyanate component. The imidization may be carried out by thermal imidization or chemical imidization, or may be produced by using these in combination.

  Here, examples of the carboxylic acid anhydride component include tetracarboxylic acid anhydride and tricarboxylic acid anhydride, but the acid anhydride is not limited to these acid anhydrides, and is an acid anhydride that reacts with an amino group or an isocyanate group As long as it is a compound having a substance group and a carboxyl group, it can be used including its derivatives. Also, these carboxylic acid anhydride components can be used alone or in combination.

  As a tetracarboxylic acid anhydride, for example, pyromellitic dianhydride, 3-fluoro pyromellitic dianhydride, 3, 6- difluoro pyromellitic dianhydride, 3, 6-bis (trifluoromethyl) piro Mellitic acid dianhydride, 3,3 ', 4,4'-benzophenonetetracarboxylic acid dianhydride, 3,3', 4,4'-biphenyltetracarboxylic acid dianhydride, 4,4'-oxydiphthalic acid Anhydride, 2,2'-difluoro-3,3 ', 4,4'-biphenyltetracarboxylic acid dianhydride, 5,5'-difluoro-3,3', 4,4'-biphenyltetracarboxylic acid Anhydride, 6,6'-difluoro-3,3 ', 4,4'-biphenyltetracarboxylic acid dianhydride, 2,2', 5,5 ', 6,6'-hexafluoro-3,3' , 4,4'-biphenyltet Carboxylic acid dianhydride, 2,2′-bis (trifluoromethyl) -3,3 ′, 4,4′-biphenyltetracarboxylic acid dianhydride, 5,5′-bis (trifluoromethyl) -3, 3 ', 4,4'-biphenyltetracarboxylic acid dianhydride, 6,6'-bis (trifluoromethyl) -3,3', 4,4'-biphenyltetracarboxylic acid dianhydride, 2,2 ' 5,5′-tetrakis (trifluoromethyl) -3,3 ′, 4,4′-biphenyltetracarboxylic acid dianhydride, 2,2 ′, 6,6′-tetrakis (trifluoromethyl) -3, 3 ', 4,4'-biphenyltetracarboxylic acid dianhydride, 5,5', 6,6'-tetrakis (trifluoromethyl) -3,3 ', 4,4'-biphenyltetracarboxylic acid dianhydride , And 2,2 ', 5,5', 6,6 Hexakis (trifluoromethyl) -3,3 ′, 4,4′-biphenyltetracarboxylic acid dianhydride, 1,2,3,4-benzenetetracarboxylic acid dianhydride, 3,3 ′ ′, 4,4 “-Terphenyltetracarboxylic acid dianhydride, 3,3 ′ ′, 4,4 ′ ′ ′-quaterphenyltetracarboxylic acid dianhydride, 3,3 ′ ′ ′, 4,4 ′ ′ ′-quinkphenyltetracarboxylic acid Dianhydride, methylene-4,4'-diphthalic acid dianhydride, 1,1-ethynylidene-4,4'-diphthalic acid dianhydride, 2,2-propylidene-4,4'-diphthalic acid 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'-di-f Tarric acid dianhydride, 2,2-bis (3,4-dicarboxyphenyl) -1,1,1,3,3,3-hexafluoropropane dianhydride, difluoromethylene-4,4'-diphthalic acid 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 anhydride , 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-dicarboxyphenyl) 1) 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 acid dianhydride, 1,2,5,6-naphthalene tetracarboxylic acid dianhydride, 3,4,9,10-perylene tetracarboxylic acid dianhydride, 2,3,6,7-anthracene tetracarboxylic acid Acid dianhydride, 1,2,7,8-phenanthrene tetracarboxylic acid dianhydride, 1,2,3,4-butane tetracarboxylic acid dianhydride, 1,2,3,4-cyclobutane tetracarboxylic acid Anhydride, cyclopentane tetracarboxylic acid dianhydride, cyclohexane-1,2,3,4-tetracarboxylic acid dianhydride, cyclohexane-1,2,4,5-tetracarboxylic acid dianhydride, 3,3 ′ 1,4,4'-bicyclohexyltetracarboxylic acid 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 (cyclohexyl) 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 di- Anhydride, 3,3 ', 5,5', 6 6'-hexafluorooxy-4,4'-diphthalic acid dianhydride, 3,3'-bis (trifluoromethyl) oxy-4,4'-diphthalic acid dianhydride, 5,5'-bis (tri acid dianhydride 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, 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'-diful 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'- diphthalic 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 acid dianhydride, 6,6'-difluoro-2,2-perfluoropropylidene-4,4'-diphthalic acid dianhydride 3, 3 ', 5,5', 6,6'-hexafluoro-2,2-perfluoropropylidene-4,4'-diphthalic dianhydride, 3,3'-bis (trifluoromethyl) -2, 2-perfluoropropylidene-4,4'-difta 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'- dif Tar acid dianhydride, 9-phenyl-9- (trifluoromethyl) xanthene-2,3,6,7-tetracarboxylic acid dianhydride, 9,9-bis (trifluoromethyl) xanthene-2,3, 6,7-tetracarboxylic acid dianhydride, bicyclo [2,2,2] oct-7-ene-2,3,5,6-tetracarboxylic acid dianhydride, 9,9-bis [4- (3) , 4-Dicarboxy) phenyl] fluorene dianhydride, 9,9-bis [4- (2,3-dicarboxy) phenyl] fluorene dianhydride, ethylene glycol bis trimellitate dianhydride, 1,2- ( Ethylene) bis (trimellitate anhydride), 1,3- (trimethylene) bis (trimellitate anhydride), 1,4- (tetramethylene) bis (trimellitate anhydride), 1, 5- (pentamethylene) bis (trimelate) Lytate anhydride), 1,6- (hexamethylene) bis (trimellitate anhydride), 1,7- (heptamethylene) bis (trimellitate anhydride), 1,8- (octamethylene) bis (trimellitate anhydride), 1,9- (nonamethylene) bis (trimellitate anhydride), 1,10- (decamethylene) bis (trimellitate anhydride), 1,12- (dodecamethylene) bis (trimellitate anhydride), 1,16- (hexadeca) Methylene) bis (trimellitate anhydride), 1, 18- (octadecamethylene) bis (trimellitate anhydride), etc. may be mentioned.

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

  As the amine component, diamines such as aliphatic diamines and aromatic diamines and polyhydric amines such as aliphatic polyether amines can be used, but the amine components are not limited to these amines. Also, these amine components may be used alone or in combination.

  Examples of the diamine include diamines having one benzene nucleus such as p-phenylenediamine (PPD), 1,3-diaminobenzene, 2,4-toluenediamine, 2,5-toluenediamine, 2,6-toluenediamine, and the like. Diaminodiphenyl ethers such as 4,4'-diaminodiphenyl ether, 3,3'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 4,4'-diaminodiphenylmethane, 3,3'-dimethyl-4,4'-diaminobiphenyl 2,2,2'-Dimethyl-4,4'-diaminobiphenyl, 2,2'-bis (trifluoromethyl) -4,4'-diaminobiphenyl, 3,3'-dimethyl-4,4'-diaminodiphenylmethane 3,3 ', 5,5'-tetramethyl-4,4'-diaminodiphenyl ester , Bis (4-aminophenyl) sulfide, 4,4'-diaminobenzanilide, 3,3'-dichlorobenzidine, 3,3'-dimethylbenzidine (o-tolidine), 2,2'-dimethylbenzidine (m -Tolidine), 3,3'-dimethoxybenzidine, 2,2'-dimethoxybenzidine, 3,3'-diaminodiphenylether, 3,4'-diaminodiphenylether, 4,4'-diaminodiphenylether, 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- 4,4'-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 ' -Diamines of benzene nuclei such as -diaminodiphenyl sulfoxide, 3,3'-dicarboxy-4,4'-diaminodiphenylmethane, etc. 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- (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) (Lufide) 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 and the like Benzene nucleus 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 and 2,2-bis [3- (3-aminophenoxy) phenyl] -1,1,1,3,3,3- Subfluoropropane, 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 4-benzene nuclei 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. Further, as described below, amines having a carboxyl group can also be used.

  Examples of amines having a carboxyl group include diaminobenzoic acids such as 3,5-diaminobenzoic acid, 2,5-diaminobenzoic acid and 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-carboxyphenyl] propane, 2,2-bis [4-amino-3-carboxyphenyl] propane, 2,2-bis [3-amino-4-carboxyphenyl] hexafluoropropane, 4,4'-diamino- Carboxy diphenyl alkanes, such as carboxy diphenyl methane etc., such as 2,2 ', 5,5'- tetracarboxy diphenylmethane, 3,3'- diamino-4,4'- dicarboxy diphenyl ether, 4,4'- diamino-3, 3 Carboxydiphenylether compounds such as '-dicarboxydiphenylether, 4,4'-diamino-2,2'-dicarboxydiphenylether, 4,4'-diamino-2,2', 5,5'-tetracarboxydiphenylether, 3, 3'-Diamino-4,4'-dicarboxydiphenylsulf 4,4'-diamino-3,3'-dicarboxydiphenylsulfone, 4,4'-diamino-2,2'-dicarboxydiphenylsulfone, 4,4'-diamino-2,2 ', 5, Diphenylsulfone compounds such as 5'-tetracarboxydiphenylsulfone, and bis [(carboxyphenyl) phenyl] alkane compounds such as 2,2-bis [4- (4-amino-3-carboxyphenoxy) phenyl] propane, 2, Examples include bis [(carboxyphenoxy) phenyl] sulfone compounds such as 2-bis [4- (4-amino-3-carboxyphenoxy) phenyl] sulfone and the like.

  As the isocyanate component, diisocyanates such as aromatic diisocyanates and their isomers or oligomers, aliphatic diisocyanates, alicyclic diisocyanates and their isomers, and other general-purpose diisocyanates can be used. It is not limited. Also, 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 thereof, polymers, hexamethylene diisocyanate And aliphatic diisocyanates such as isophorone diisocyanate, dicyclohexylmethane diisocyanate and xylylene diisocyanate, or alicyclic diisocyanates and isomers obtained by hydrogenating aromatic diisocyanate, or diisocyanates for other general purpose.

  The alkali-soluble resin having an imide ring or an imide precursor skeleton as described above may have an amide bond. This may be an amide bond obtained by reacting an isocyanate and a carboxylic acid, or may be another reaction. Furthermore, it may have a bond consisting of other additions and condensations.

  In addition, for the introduction of the imide ring or imide precursor skeleton into this alkali-soluble resin, known alkali-soluble polymers, oligomers, monomers having one or both of a carboxyl group and an acid anhydride group are commonly used. For example, a resin obtained by reacting these known and commonly used alkali-soluble resins alone or in combination with the above-mentioned carboxylic anhydride component with the above-mentioned amines / isocyanates It may be.

  In the synthesis of an alkali-soluble resin having such an alkali-soluble group and an imide ring or an imide precursor skeleton, known organic solvents can be used. There is no problem as long as the organic solvent is a solvent which does not react with the raw material carboxylic acid anhydrides, amines, and isocyanates and in which these raw materials are dissolved, and the structure is not particularly limited. Specific examples thereof include amide solvents such as N, N-dimethylformamide, N, N-dimethylacetamide, N-methylpyrrolidone, γ-butyrolactone, γ-valerolactone, δ-valerolactone, γ-caprolactone, ε-caprolactone Cyclic ester solvents such as α-methyl-γ-butyrolactone, carbonate solvents such as ethylene carbonate and propylene carbonate, lactam solvents such as caprolactam, ether solvents such as dioxane, glycol solvents such as triethylene glycol, m-cresol, Phenolic solvents such as p-cresol, 3-chlorophenol, 4-chlorophenol, 4-methoxyphenol, 2,6-dimethylphenol, acetophenone, 1,3-dimethyl-2-imidazolidinone, sulfolane, dimethyl Sulfo Sid, such as tetramethylurea. Furthermore, other common organic solvents, namely, phenol, o-cresol, butyl acetate, ethyl acetate, isobutyl acetate, propylene glycol methyl acetate, ethyl cellosolve, butyl cellosolve, 2-methyl cellosolve acetate, ethyl cellosolve acetate, butyl cellosolve acetate, Tetrahydrofuran, dimethoxyethane, diethoxyethane, dibutyl ether, diethylene glycol dimethyl ether, methyl isobutyl ketone, diisobutyl ketone, cyclohexanone, methyl ethyl ketone, acetone, butanol, ethanol, xylene, toluene, chlorobenzene, turpent, mineral spirit, petroleum naphtha solvent Etc. can also be added and used. Among them, aprotic solvents such as N, N-dimethylformamide, N, N-dimethylacetamide, N-methyl-2-pyrrolidone, dimethylsulfoxide and γ-butyrolactone are preferable because of high solubility of the raw material.

  The alkali-soluble resin having an alkali-soluble group such as a carboxyl group or an acid anhydride group as described above and an imide ring or imide precursor skeleton has an acid value of 20 to 200 mg KOH in order to correspond to a photolithography process. / G is preferable, and 60 to 150 mg KOH / g is more preferable. When the acid value is 20 mg KOH / g or more, the solubility in alkali increases and the developability becomes good, and furthermore, the degree of cross-linking with the thermosetting component after light irradiation becomes high, so a sufficient development contrast is obtained be able to. In addition, when the acid value is 200 mg KOH / g or less, so-called heat fogging in the PEB (POST EXPOSURE BAKE) process after light irradiation described later can be suppressed, and the process margin becomes large.

  Moreover, the molecular weight of the alkali-soluble resin is preferably 1,000 to 100,000, and more preferably 2,000 to 50,000, in view of developability and cured coating characteristics. When this molecular weight is 1,000 or more, sufficient development resistance and cured physical properties can be obtained after exposure and PEB. When the molecular weight is 100,000 or less, the alkali solubility is increased and the developability is improved.

  When a photobase generator is used, a resin composition containing an alkali-soluble resin having an imide ring or an imide precursor skeleton usually has, in addition to the alkali-soluble resin, a photobase generator and a thermally reactive compound. When it contains and a photoinitiator is used, in addition to alkali-soluble resin, the compound which has a photoinitiator and an ethylenically unsaturated bond is contained. Moreover, you may use together a carboxyl group-containing urethane resin, a carboxyl group-containing novolak resin etc. as a resin component.

  The photobase generator is one or more species that can function as a catalyst for the polymerization reaction of the heat-reactive compound described later, when the molecular structure is changed by irradiation with light such as ultraviolet light or visible light, or the molecule is cleaved. It is a compound that produces a basic substance. Examples of the basic substance include secondary amines and tertiary amines.

  As the photo base generator, for example, α-aminoacetophenone compounds, oxime ester compounds, acyloxyimino groups, N-formylated aromatic amino groups, N-acylated aromatic amino groups, nitrobenzyl carbamate groups, alcooxybenzyls The compound etc. which have substituents, such as a carbamate group, are mentioned. Among them, oxime ester compounds and α-aminoacetophenone compounds are preferable. As the α-aminoacetophenone compound, one having two or more nitrogen atoms is particularly preferable.

  Other photobase generators include WPBG-018 (trade name: 9-anthrylmethyl N, N'-diethylcarbamate), WPBG-027 (trade name: (E) -1- [3- (2-hydroxyphenyl) -2 -Propenoyl] piperidine, WPBG-082 (trade name: guanidinium 2- (3-benzoylphenyl) propionate), WPBG-140 (trade name: 1- (anthraquinon-2-yl) ethyl imidazole carboxylate), etc. can 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 form a basic substance (amine) that exerts 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) or a solution thereof can be used.

  As the oxime ester compound, any compound can be used as long as it produces a basic substance by light irradiation. As such oxime ester compounds, commercially available products include CGI-325 manufactured by BASF Japan Ltd., Irgacure OXE01, Irgacure OXE02, N-1919 manufactured by Adeka Corporation, NCI-831 and the like. Moreover, the compound which has two oxime ester groups in the molecule | numerator described in the patent 4344400 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, The carbazole oxime ester compounds described in JP-A-2009-040762 and JP-A-2011-80036 can be exemplified.

  As such photobase generators, one type may be used alone, or two or more types may be used in combination. The compounding amount of the photobase generator in the resin composition is preferably 0.1 to 40 parts by mass, and more preferably 0.1 to 30 parts by mass with respect to 100 parts by mass of the heat-reactive compound. In the case of 0.1 mass part or more, the contrast of development resistance of a light irradiation part / unirradiated part can be obtained favorably. When the amount is 40 parts by mass or less, the cured product properties are improved.

  The heat-reactive compound is a resin having a functional group capable of curing by heat, and includes an epoxy resin, a polyfunctional oxetane compound, and the like.

  The epoxy resin is a resin having an epoxy group, and any known epoxy resin can be used. Specific examples thereof include bifunctional epoxy resins having two epoxy groups in the molecule, and polyfunctional epoxy resins having a large number of epoxy groups in the molecule. In addition, the hydrogenated bifunctional epoxy compound may be sufficient.

  As said epoxy compound, bisphenol A type epoxy resin, brominated epoxy resin, novolak type epoxy resin, bisphenol F type epoxy resin, hydrogenated bisphenol A type epoxy resin, glycidyl amine type epoxy resin, hydantoin type epoxy resin, alicyclic Epoxy resin, trihydroxyphenylmethane type epoxy resin, bixylenol type or biphenol type epoxy resin or mixture thereof; bisphenol S type epoxy resin, bisphenol A novolac type epoxy resin, tetraphenylol ethane type epoxy resin, heterocyclic epoxy resin , Diglycidyl phthalate resin, tetraglycidyl xylenoyl ethane resin, naphthalene group-containing epoxy resin, epoxy resin having dicyclopentadiene skeleton, glycidyl meta Acrylate copolymer 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, (3 ′, 4′-epoxy-6′-methyl Mention may be made of cycloaliphatic epoxy resins such as cyclohexylmethyl) -3,4-epoxy-6-methylcyclohexanecarboxylate. One of these epoxy resins may be used alone, or two or more thereof may be used in combination.

  Examples of the polyfunctional oxetane compounds include bis [(3-methyl-3-oxetanylmethoxy) methyl] ether, bis [(3-ethyl-3-oxetanylmethoxy) methyl] ether, and 1,4-bis [(3-methyl] -3-oxetanylmethoxy) methyl] benzene, 1,4-bis [(3-ethyl-3-oxetanylmethoxy) methyl] benzene, (3-methyl-3-oxetanyl) methyl acrylate, (3-ethyl-3-oxetanyl) ) Multi-functional oxetanes such as methyl acrylate, (3-methyl-3-oxetanyl) methyl methacrylate, (3-ethyl-3-oxetanyl) methyl methacrylate and their oligomers or copolymers, as well as oxetane alcohol and novolac resin, Poly (p-hydroxystyrene), cardo type bis fe Lumpur acids, calixarenes, calix resorcin arenes, or the like ethers of a resin having a hydroxyl group such as silsesquioxane and the like. In addition, copolymers of an unsaturated monomer having an oxetane ring and an alkyl (meth) acrylate are also included.

  As a compounding quantity of the said heat-reactive compound, equivalent ratio (alkali-soluble group such as a carboxyl group: heat-reactive group such as an epoxy group) with the alkali-soluble resin is 1: 0.1 to 1:10. Is preferred. By setting it as such a compounding ratio range, development becomes favorable and a fine pattern can be formed easily. The equivalent ratio is more preferably 1: 0.2 to 1: 5.

  As the photopolymerization initiator, known photopolymerization initiators can be used. For example, α-aminoacetophenone photopolymerization initiator, acyl phosphine oxide photopolymerization initiator, benzoin compound, acetophenone compound, anthraquinone compound, thioxanthone Compounds, ketal compounds, benzophenone compounds, tertiary amine compounds, xanthone compounds and the like can be mentioned.

  In addition, as compounds having an ethylenically unsaturated bond, known compounds can be used, and hydroxyalkyl acrylates such as 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, etc .; ethylene glycol, methoxytetraethylene glycol, polyethylene glycol Mono- or di-acrylates of glycols such as propylene glycol; polyhydric alcohols such as hexanediol, trimethylolpropane, pentaerythritol, dipentaerythritol, tris-hydroxyethyl isocyanurate or their ethylene oxide adducts or propylene oxide adducts And other polyhydric acrylates; phenoxy acrylate, bisphenol A diacrylate, and ethylene oxide of these phenols Side adduct or propylene oxide adduct and the like acrylates such.

(Adhesive layer (A))
The alkali-developable resin composition constituting the adhesive layer (A) is a composition containing one or more functional groups among phenolic hydroxyl group, thiol group and carboxyl group and containing a resin developable with an alkaline solution. Any photocurable resin composition or thermosetting resin composition may be used. Preferably, a resin composition containing a compound having two or more phenolic hydroxyl groups, a carboxyl group-containing resin, a compound having a phenolic hydroxyl group and a carboxyl group, and a compound having two or more thiol groups is exemplified. Used.

  Specifically, for example, a carboxyl group-containing resin or a carboxyl group-containing photosensitive resin, which is conventionally used as a solder resist composition, a compound having an ethylenically unsaturated bond, a photopolymerization initiator, and heat reactivity. The photocurable thermosetting resin composition containing a compound is mentioned. Further, a resin composition containing a carboxyl group-containing urethane resin, a resin having a carboxyl group, a photobase generator and a thermosetting component can also be used. Such a resin composition is developed by causing an addition reaction between a urethane resin having a carboxyl group and a thermosetting component by heating after exposure using a base generated from a photobase generator as a catalyst, and removing an unexposed part by an alkaline solution. Is possible.

  As each material which comprises the resin composition used for a contact bonding layer (A), in addition to a well-known and commonly used thing, the thing used in the said protective layer (B) can be used similarly.

  In the present invention, the elongation percentage of the adhesive layer (A) is not particularly limited and is preferably as high as possible, but it is preferably 1 to 50%, more preferably 2 to 40% at room temperature as a cured film.

  In the resin composition used in the adhesive layer (A) and the protective layer (B), a conventional and commonly used polymer resin may be blended for the purpose of improving the flexibility and the touch-drying property of the cured product obtained. it can. Examples of such polymer resins include cellulose-based, polyester-based, phenoxy resin-based polymers, polyvinyl acetal-based, polyvinyl butyral-based, polyamide-based, polyamideimide-based binder polymers, block copolymers, and elastomers. The polymer resin may be used alone or in combination of two or more.

  In addition, in the resin composition used in the adhesive layer (A) and the protective layer (B), in order to suppress the cure shrinkage of the cured product and improve the properties such as adhesion and hardness, an inorganic filler should be blended. Can. As such an inorganic filler, for example, barium sulfate, amorphous silica, fused silica, spherical silica, talc, clay, magnesium carbonate, calcium carbonate, aluminum oxide, aluminum hydroxide, silicon hydroxide, silicon nitride, aluminum nitride, boron nitride, Neuburg-Silichas Earth etc. may be mentioned.

  Furthermore, a well-known and usual coloring agent can be mix | blended with the resin composition used in an adhesive layer (A) and a protective layer (B). Conventionally, at the edge portion of a copper circuit in a printed wiring board, when the coloring power of the pattern layer is insufficient, copper discolors in the heat history after forming the pattern layer, and only a thin portion appears to discolor in appearance. Typical thermal histories include thermal curing of marking, recursion, preheating before mounting, mounting, and the like. For this reason, conventionally, the problem that only the edge portion of the copper circuit appears discolored appears to be solved by blending a large amount of colorant in the pattern layer to enhance the coloring power. However, since the coloring agent has light absorbability, it prevents the light from transmitting to the deep part. As a result, in the composition containing a coloring agent, it is difficult to obtain sufficient adhesion because an undercut easily occurs.

  On the other hand, when the resin composition contains a photobase generator, the base can be chemically grown to the deep part of each layer, so that the resin can be sufficiently cured to the deep part of each layer. It is possible to form a pattern layer which is excellent in concealability and excellent in adhesion.

  In the resin composition used in the adhesive layer (A) and the protective layer (B), an organic solvent is used for preparation of the resin composition, and for viscosity adjustment for coating on a substrate or carrier film Can. As such an organic solvent, ketones, aromatic hydrocarbons, glycol ethers, glycol ether acetates, esters, alcohols, aliphatic hydrocarbons, petroleum solvents and the like can be mentioned. Such an organic solvent may be used individually by 1 type, and may be used as 2 or more types of mixtures.

  The resin composition used in the adhesive layer (A) and the protective layer (B) may further contain components such as a mercapto compound, an adhesion promoter, an antioxidant, and an ultraviolet light absorber, if necessary. As these, conventional ones known in the field of electronic materials can be used. In addition, known conventional thickeners such as fine powder silica, hydrotalcite, organic bentonite and montmorillonite, antifoaming agents and leveling agents such as silicone type, fluorine type and polymer type, silane coupling agents, antirust agents, etc. Such known and commonly used additives can be suitably blended.

  In the laminated structure of the present invention, the adhesive layer 3 is preferably thicker than the protective layer 4 from the viewpoint of the ability to follow a copper circuit.

  The laminated structure of the present invention can be used for at least one of bent portions and non-bent portions of a flexible printed wiring board, preferably both, and thereby flexible printed wiring having sufficient durability against bending. A board can be obtained while improving cost and workability. Specifically, the laminated structure of the present invention can be used for at least any one of a coverlay of a flexible printed wiring board, a solder resist, and an interlayer insulating material.

(Method of manufacturing flexible printed wiring board)
In the present invention, the layer of the above laminated structure is formed directly or via a dry film on a flexible printed wiring substrate, patterned by light irradiation, and patterns are collectively formed by a developer to form an insulating film. By forming, a flexible printed wiring board can be obtained. In the single layer of the conventional solder resist layer, the properties such as flexibility are poor, but according to the present invention, the laminated structure comprising the adhesive layer 3 and the protective layer 4 is used, and the protective layer 4 is a room temperature as a cured film. To provide an insulating film for a flexible printed wiring board having sufficient durability against bending while improving cost performance and workability by using a material having an elongation percentage of at least 2.5%. It has become possible.

  Below, about an example of the method of manufacturing the flexible printed wiring board of this invention from the laminated structure of this invention, a resin composition containing a photobase generator and a heat-reactive compound about both the contact bonding layer 3 and the protective layer 4 The case where an object is used will be described based on the process chart shown in FIG. It contains a carboxyl group-containing resin or a carboxyl group-containing photosensitive resin, a compound having an ethylenically unsaturated bond, a photopolymerization initiator, and a thermally reactive compound, which are conventionally used as a solder resist composition. When using a photocurable thermosetting resin composition, the same process as a solder resist can be taken.

[Lamination process]
The laminating step is a step of forming the laminated structure of the present invention on a substrate. In the laminating step in FIG. 1, a laminated structure including an adhesive layer 3 made of an alkali-developable resin composition and a protective layer 4 is formed on the flexible printed wiring substrate 1 on which the copper circuit 2 is formed. Show the condition.

  Here, each layer constituting the laminated structure is formed by, for example, sequentially applying and drying the resin composition constituting the adhesive layer 3 and the protective layer 4 on the base material. It can form directly by laminating the thing which made the form of a dry film the resin composition which forms adhesion layer 3 and protective layer 4 into a dry film one by one to a substrate one by one. Moreover, you may form by the method of laminating the laminated structure made into the dry film form of 2 layer structure on a base material. In this case, at least one side of the laminated structure can be supported or protected by a film. As a film to be used, a plastic film which can be peeled off from the laminated structure can be used. Although there is no restriction | limiting in particular about the thickness of a film, Generally, it selects suitably in 10-150 micrometers. From the viewpoint of coating film strength, the interface between each layer may be compatible.

  The method for applying the resin composition to the substrate may be a known method such as a blade coater, a lip coater, a comma coater, or a film coater. In addition, the drying method is a method of making the hot air in the dryer countercurrently contact, using a hot air circulation type drying furnace, an IR furnace, a hot plate, a convection oven, or the like provided with a heat source of heating by steam. A known method such as a method of spraying on a support may be used.

  Here, the substrate is a flexible printed wiring substrate on which a circuit is formed in advance. In addition to the intended effect, an additional layer may be provided between the adhesive layer 3 and the protective layer 4 in order to obtain other effects.

[Light irradiation process]
The light irradiation step is a step of activating the photobase generator contained in the resin composition by light irradiation in a negative pattern, and curing the light irradiation portion. In this light irradiation step, the mask 5 is disposed on the protective layer 4 and light is irradiated in a negative pattern to activate the photo base generator contained in the resin composition and cure the light irradiation portion. .

  In this step, the photobase generator is destabilized by the base generated in the light irradiation part, and a basic substance (hereinafter sometimes abbreviated as "base") is generated from the photobase generator, and this generation occurs. The photobase generator is destabilized by the base to further generate a base. Thus, it is considered that the base can be sufficiently cured to the deep part of each layer by generating and chemically propagating to the deep part of each layer. In the subsequent heat curing, the addition reaction proceeds while the base acts as a catalyst for the addition reaction between the alkali developable resin and the thermally reactive compound, so that in the light irradiation section, each layer is sufficiently deep Thermoset. Curing of the resin composition in this case is, for example, a ring-opening reaction of epoxy by thermal reaction, so that distortion and curing shrinkage can be suppressed as compared with the case of proceeding by photo reaction.

  As a light irradiator used for light irradiation, a direct drawing device (for example, a laser direct imaging device that draws an image directly by a laser according to CAD data from a computer), a light irradiator equipped with a metal halide lamp, (ultra) high pressure mercury lamp A light irradiator equipped with a mercury irradiator, a light irradiator equipped with a mercury short arc lamp, or a direct drawing apparatus using an ultraviolet lamp such as a (super) high pressure mercury lamp can be used. The pattern-like light irradiation mask is a negative mask.

As active energy rays, it is preferable to use laser light or scattered light having a maximum wavelength in the range of 350 to 410 nm. By setting the maximum wavelength in this range, the photobase generator can be efficiently activated. As long as a laser beam within this range is used, the type of laser may be either a gas laser or a solid laser. The amount of light irradiation varies depending on the film thickness and the like, but can generally be in the range of 100 to 1,500 mJ / cm ² , preferably 300 to 1,500 mJ / cm ² .

[Heating process]
A heating process hardens a light irradiation part by heating, and can be hardened to a deep part with a base generated at a light irradiation process. This heating process is a process of curing the light irradiation part by heating the adhesive layer 3 and the protective layer 4 after the light irradiation process, and is a process called a so-called PEB (POST EXPOSURE BAKE) process. Thus, each layer can be sufficiently cured to the deep portion with the base generated in the light irradiation step, and a pattern layer having excellent curing characteristics can be obtained.

  For example, the heating step is preferably performed at a temperature lower than the heat generation start temperature or heat generation peak temperature of the non-irradiated resin composition and higher than the heat generation start temperature or heat generation peak temperature of the light irradiated resin composition. . By heating in this manner, only the light irradiation part can be selectively cured.

  Here, it is preferable that the heating temperature at this time is a temperature at which the light irradiated portion of the resin composition is thermally cured but the non-irradiated portion is not thermally cured. The heating temperature is, for example, 80 to 140 ° C. By setting the heating temperature to 80 ° C. or more, the light irradiation part can be sufficiently cured. On the other hand, by setting the heating temperature to 140 ° C. or less, only the light irradiation portion can be selectively cured. The heating time is, for example, 10 to 100 minutes. The heating method is the same as the above-mentioned drying method. In the non-irradiated part, since the photobase generator does not generate a base, the thermal curing is suppressed.

[Development process]
In the development step, the non-irradiated part is removed by alkali development to form a negative pattern layer. The developing step in FIG. 1 shows a step of developing the adhesive layer 3 and the protective layer 4 with an alkaline aqueous solution to remove the non-irradiated part, thereby forming a negative pattern layer. The developing method may be a known method such as a dipping method, a shower method, a spray method or a brush method. Further, as a developer, amines such as potassium hydroxide, sodium hydroxide, sodium carbonate, potassium carbonate, sodium phosphate, sodium silicate, sodium silicate, ammonia, ethanolamine and the like, alkalis such as aqueous solution of tetramethyl ammonium hydroxide (TMAH) An aqueous solution or a mixture thereof can be used.

[Second light irradiation process]
After the developing step, it is preferable to include a second light irradiation step. The second light irradiation step is a step of irradiating ultraviolet light as desired in order to generate a base by activating the photobase generator remaining without being activated in the pattern layer of the light irradiation step. . The wavelength of the ultraviolet light and the light irradiation amount (exposure amount) in the second light irradiation step may be the same as or different from the light irradiation step. The light irradiation amount (exposure amount) is, for example, 150 to 2000 mJ / cm ² .

[Thermosetting process]
After the development step, it is preferable to further include a heat curing (post curing) heat curing step. The heat curing step is a step of performing heat curing (post curing) as necessary in order to heat cure the pattern layer sufficiently. When the second light irradiation step and the heat curing step are both performed after the development step, the heat curing step is preferably performed after the second light irradiation step.

  In this heat curing step, the pattern layer is sufficiently heat cured by the base generated from the photobase generator in the light irradiation step or the light irradiation step and the second light irradiation step. At the time of the heat curing step, since the non-irradiated part has already been removed, the heat curing step can be performed at a temperature higher than the curing reaction start temperature of the non-irradiated resin composition. Thereby, the pattern layer can be sufficiently thermally cured. The heating temperature is, for example, 150 ° C. or more.

Hereinafter, the present invention will be described in more detail using examples.
Synthesis Example 1
<Synthesis of Alkali-Soluble Resin Having Imide Ring>
In a separable 3-neck flask equipped with a stirrer, a nitrogen inlet tube, a fractional ring and a cooling ring, 12.2 g of 3,5-diaminobenzoic acid, 2,2'-bis [4- (4-aminophenoxy) Add 8.2 g of phenyl] propane, 30 g of NMP, 30 g of γ-butyrolactone, 27.9 g of 4,4'-oxydiphthalic anhydride, 3.8 g of trimellitic anhydride, and add 100 rpm under a nitrogen atmosphere at room temperature. Stir for 4 hours. Next, 20 g of toluene was added, and stirring was carried out for 4 hours while distilling off toluene and water at a silicon bath temperature of 180 ° C. and 150 rpm to obtain an imide ring-containing alkali-soluble resin solution. Then, (gamma) -butyrolactone was added so that solid content might be 30 mass%. The obtained resin solution had a solid content acid value of 86 mg KOH / g and a Mw of 10000.

(Composition example 2)
<Carboxyl group-containing urethane resin>
In a reaction vessel equipped with a stirrer, a thermometer and a condenser, 2400 g of polycarbonate diol (Asahi Kasei Chemicals Co., Ltd. T5650 J, number average molecular weight 800) derived from 1,5-pentanediol and 1,6-hexanediol (3 moles), 603 g (4.5 moles) of dimethylol propionic acid, and 238 g (2.6 moles) of 2-hydroxyethyl acrylate as a monohydroxyl compound were charged. Next, 1887 g (8.5 mol) of isophorone diisocyanate as polyisocyanate is added, heating to 60 ° C. with stirring and stopping, and when the temperature in the reaction vessel starts to decrease, it is heated again and stirred at 80 ° C. The reaction was terminated after confirming that the absorption spectrum (2280 cm ⁻¹ ) of the isocyanate group disappeared in the infrared absorption spectrum. Then, carbitol acetate was added so that solid content might be 50 mass%. The acid value of the solid content of the obtained carboxyl group-containing resin was 50 mg KOH / g.

<Preparation of Resin Composition Constituting Each Layer>
According to the composition described in Tables 1 and 2 below, the materials described in the Examples and Comparative Examples are respectively compounded, pre-mixed by a stirrer, and then kneaded by a three-roll mill to form an adhesive layer and a protective layer. Prepared. The values in the table are parts by mass unless otherwise specified.

<Formation of Adhesive Layer (A)>
A flexible printed wiring substrate on which a circuit with a copper thickness of 18 μm was formed was prepared, and was pretreated using CZ-8100 manufactured by MEC Corporation. Then, the resin composition for each adhesive layer was apply | coated so that the film thickness after drying might be set to 25 micrometers to the flexible printed wiring base material which pre-processed. Then, it dried at 90 degreeC / 30 minutes in a hot-air circulation type drying furnace, and formed the contact bonding layer (A) which consists of a resin composition. In Comparative Examples 2 and 3, no adhesive layer was formed.

<Formation of Protective Layer (B)>
The resin composition for each protective layer was apply | coated so that the film thickness after drying might be set to 10 micrometers on the said contact bonding layer (A). Then, it dried at 90 degreeC / 30 minutes in a hot-air circulation type drying furnace, and formed the protective layer (B) which consists of resin compositions. In Comparative Example 4, the protective layer (B) was not formed.

  The cured film of each adhesive layer (A) and the protective layer (B) was subjected to a tensile rate of 1.0 mm / min according to JIS K 7127 using a tensile tester (manufactured by Shimadzu Corporation, AGS-G100W). Elongation (tensile fracture elongation) was measured at 23 ° C.

<Alkali developability (patterning) and bendability evaluation>
The substrate provided with the adhesive layer and the protective layer obtained above was irradiated with a negative pattern at a dose of 500 mJ / cm ² with HMW 680 GW (a metal halide lamp, scattered light) manufactured by ORC. Then, heat treatment was performed at 90 ° C. for 60 minutes. Thereafter, the substrate was immersed in an aqueous solution of sodium carbonate at 30 ° C. and 1% by mass, and development was performed for 3 minutes to evaluate the alkali developability.

  Next, heat treatment was carried out at 150 ° C./60 minutes using a hot air circulation type drying furnace to obtain a cured film in the form of a pattern. The obtained cured coating film was subjected to MIT test (R = 0.38 mm / using UPILEX 12.5 μm substrate manufactured by Ube Industries, Ltd.) to evaluate flexibility. If it is about 120 cycles or more, the flexibility as a flexible printed wiring board can be satisfied.

  In addition, the obtained cured coating was used for cold folding, and the number of times before the crack was entered was recorded. The case where the sheet was bent three times or more is represented by ○, and the case where the number of bendings is two or less is represented by x.

  The obtained results are shown in Tables 1 and 2 below.

※１：合成例１の樹脂
※２：合成例２の樹脂
※３：カルボキシル基含有ノボラック樹脂（酸価１０４ｍｇＫＯＨ／ｇ，Ｂｉｓ Ａ／フェノールノボラック樹脂）
※４：トリメチロールプロパンＥＯ変性トリアクリレート（東亞合成（株）製）
※５：ビスフェノールＡ型エポキシ樹脂（分子量９００）（三菱化学（株）製）
※６：ビスフェノールＡ型エポキシ樹脂（分子量４００）（三菱化学（株）製）
※７：オキシム型光重合開始剤（ＢＡＳＦジャパン社製）
※８：アシルホスフィンオキサイド系光重合開始剤（ＢＡＳＦジャパン社製）
※９：ビスフェノールＦ型変性エポキシアクリレート（日本化薬（株）製）

* 1: Resin of Synthesis Example 1 * 2: Resin of Synthesis Example 2 * 3: Carboxyl group-containing novolak resin (acid value: 104 mg KOH / g, Bis A / phenol novolac resin)
* 4: Trimethylolpropane EO modified triacrylate (manufactured by Toagosei Co., Ltd.)
* 5: Bisphenol A epoxy resin (molecular weight 900) (Mitsubishi Chemical Corporation)
※ 6: Bisphenol A epoxy resin (molecular weight 400) (Mitsubishi Chemical Corporation)
* 7: Oxime type photopolymerization initiator (manufactured by BASF Japan Ltd.)
* 8: Acyl phosphine oxide photopolymerization initiator (manufactured by BASF Japan Ltd.)
※ 9: Bisphenol F type modified epoxy acrylate (manufactured by Nippon Kayaku Co., Ltd.)

  As apparent from the evaluation results shown in Tables 1 and 2 above, an adhesive layer (A) comprising an alkali-developable resin composition, and a protective layer having an elongation of 2.5% or more at room temperature as a cured film ( The flexible printed wiring board of each of the examples and reference examples using the laminated structure obtained by laminating B) has good developability and Comparative Example 1 which does not satisfy the condition of elongation, and an adhesive layer or protection As compared with the flexible printed wiring boards of Comparative Examples 2 to 4 comprising single layers of only one of the layers, it was confirmed to be excellent in both the MIT test and the fold test. Further, from the comparison between Example 1 and Comparative Example 2, even if the elongation rate is the same 5%, by using a laminated structure instead of a single layer, the flexibility is significantly improved, and the wire is folded It can be seen that the performance is improving.

1 flexible printed wiring substrate 2 copper circuit 3 adhesive layer 4 protective layer 5 mask

Claims (6)

A laminated structure comprising: an adhesive layer (A) comprising an alkali-developable resin composition; and a protective layer (B) laminated to a flexible printed wiring board via the adhesive layer (A),
The protective layer (B) is composed of a resin composition containing an alkali-soluble resin having an imide ring or an imide precursor skeleton, a photobase generator, and a thermally reactive compound.
The elongation of the adhesive layer (A) at room temperature as a cured film is 2% or more and 40% or less, and the elongation of the protective layer (B) as a cured film at room temperature is 2.5% or more Laminated structure characterized by being 40% or less .   The laminated structure according to claim 1, wherein both the adhesive layer (A) and the protective layer (B) can be patterned by light irradiation. The laminated structure according to claim 1 or 2, which is used in at least one of a bent portion and a non-bent portion of a flexible printed wiring board. The laminated structure according to any one of claims 1 to 3 , which is used for at least one application among a coverlay of a flexible printed wiring board, a solder resist, and an interlayer insulating material. A dry film characterized in that at least one surface of the laminated structure according to any one of claims 1 to 4 is supported or protected by a film. The layer of the laminated structure according to any one of claims 1 to 4 is directly formed on the flexible printed wiring board, or the layer of the laminated structure is formed through the dry film according to claim 5 What is claimed is: 1. A flexible printed wiring board comprising: an insulating film formed by patterning a pattern by light irradiation and collectively forming a pattern with a developing solution.

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