JP5858734B2 - Novel flexible printed circuit board and method for producing the same - Google Patents

Description

  The present invention relates to a flexible printed wiring board excellent in fine workability, low warpage, flexibility, and crease resistance, and a method for producing the same.

  Conventionally, a coverlay film obtained by applying an adhesive to a molded body such as a polyimide film having excellent electrical insulation reliability, heat resistance, chemical resistance and mechanical properties has been aligned with the insulating film of a flexible printed wiring board. A method of using a cover coat obtained by thermocompression bonding with a hot press or the like, a method in which a solution obtained by dissolving a polyimide resin or the like in an organic solvent is directly applied on a wiring circuit and then cured after drying the solvent, There is a method of using a photosensitive solder resist which is cured after applying a fine processing of an opening by photolithography after directly applying a photosensitive thermosetting resin composition mainly composed of acid-modified epoxy acrylate or epoxy resin on a circuit. Has been taken.

  However, in the case of a method using a coverlay film, it is difficult to provide a highly accurate opening in a thin film, and the alignment at the time of bonding is often performed manually, so the positional accuracy is poor, The workability of pasting was poor and the cost was high. In the case of a method using a cover coat, it is difficult to provide a highly accurate opening because it is necessary to paint the opening and other parts separately by a printing technique such as screen printing (see, for example, Patent Document 1). .) In the case of a method using a photosensitive solder resist, an opening can be formed by photolithography, so that it is excellent in fine workability, but flexibility such as flexibility is poor, and curing shrinkage is large. When laminated on a flexible circuit board, there is a problem that the warpage of the board becomes large. (For example, refer to Patent Document 2). In particular, electronic devices such as mobile phones and digital cameras have a very small space left in the circuit and wiring for miniaturization, weight reduction, high functionality, and high density, making this limited space effective. There is a need for an insulating wiring material that is excellent in low warpage, flexibility, and breakage resistance while maintaining high fine workability so that it can be used.

International Publication No. 2007/125806 JP 2000-241969 A

  With the reduction in mounting space, recent flexible printed wiring boards are required to have mountability such as low warpage, flexibility, and bend resistance in addition to fine workability. In general, for fine processing using a photosensitive solder resist, an exposed (UV cured) part and an unexposed part are formed by irradiating a photosensitive thermosetting resin composition with ultraviolet rays, and then a dilute alkaline aqueous solution. To develop the unexposed area. Under the present circumstances, since the crosslinking density of the photosensitive thermosetting resin composition increases by exposure hardening, an insulating film becomes inevitably fragile. For this reason, it has been very difficult to achieve both fine workability, low warpage, flexibility, and crease resistance in the conventional method for producing a flexible printed wiring board using a photosensitive solder resist.

  As a result of intensive studies on the above problems, the inventors of the present application have found that the insulating film on the same flexible printed wiring board is exposed to heat and heat cured at a first location, and is exposed to heat without being cured. It is possible to obtain a flexible printed wiring board excellent in fine workability, low warpage, flexibility, and bend resistance, and in addition, the first location and the second location are one. Since it can be obtained by coating various types of photosensitive thermosetting resin compositions, it is simpler than the method for producing a flexible printed wiring board in which the photosensitive resin composition and the thermosetting resin composition are separately applied. The manufacturing method which improves productivity was discovered.

  That is, the present invention has a first location where the insulating film on the same flexible printed circuit board is exposed and cured by heat, and a second location where the insulating film is thermally cured without being exposed and cured. The present invention relates to a flexible printed wiring board characterized in that the part and the second part are obtained from the same photosensitive thermosetting resin composition.

  The photosensitive thermosetting resin composition preferably contains at least (A) a base polymer, (B) a radical polymerizable compound, (C) a photopolymerization initiator, and (D) a thermosetting resin.

  Moreover, it is preferable that the said 1st location is patterned.

  Moreover, it is preferable that the first portion is alkali-developed.

  In addition, another invention of the present application is that after the photosensitive thermosetting resin composition is applied and dried on the flexible printed wiring board, the first portion is exposed and cured, and then the first portion and the second portion. It is related with the manufacturing method of the flexible printed wiring board characterized by forming an insulating film by thermosetting this.

  In addition, another invention of the present application is that after applying and drying the photosensitive thermosetting resin composition on the flexible printed wiring board, after thermally curing the second location, the first location is then exposed and cured, Furthermore, it is related with the manufacturing method of the flexible printed wiring board characterized by forming an insulating film by thermosetting a 1st location and a 2nd location.

  As described above, the flexible printed wiring board of the present invention is the first where the insulating film on the same flexible printed wiring board is exposed and cured by heat, and secondly cured without being exposed and cured. The first part and the second part are obtained from the same photosensitive thermosetting resin composition, so that the flexibility excellent in fine workability, low warpage, flexibility, and bending resistance is obtained. A printed wiring board can be obtained. In addition, since the first location and the second location are obtained by applying one type of photosensitive thermosetting resin composition, the photosensitive resin composition and the thermosetting resin composition are applied separately. Compared with the manufacturing method of a flexible printed wiring board, it is a manufacturing method which is simpler and productivity is improved. Therefore, the flexible printed wiring board and the method for producing the same of the present invention can be used for various circuit boards and methods for producing the same, and have excellent effects.

It is a figure which shows an example of the 1st location and the 2nd location on the same flexible printed wiring board. It is a figure which shows an example of the manufacturing method of the flexible printed wiring board which forms an insulating film by heat-curing a 1st location and a 2nd location after exposing and hardening a 1st location. A method for manufacturing a flexible printed wiring board in which an insulating film is formed by heat-curing the first location and the second location after the second location is thermally cured after the second location is thermally cured. It is a figure which shows an example. It is a figure which shows having formed the 1st location and the 2nd location on the comb-shaped pattern. It is a schematic diagram which is doing the flexibility test.

  Hereinafter, about this invention, the method of forming a 1st location and a 2nd location on a photosensitive thermosetting resin composition and the same flexible printed wiring board is demonstrated in detail.

[Photosensitive thermosetting resin composition]
The photosensitive thermosetting resin composition of the present invention is not particularly limited as long as it is a resin composition having photosensitivity and thermosetting property, but preferably at least (A) a base polymer and (B) a radical polymerizable compound. , (C) a photopolymerization initiator, and (D) a resin composition containing a thermosetting resin. In addition, the photosensitive thermosetting resin composition in the present invention is not limited as long as it is a material capable of fulfilling a function required for a cured insulating film. Here, as the above-mentioned required functions, it can be cured at a low temperature (200 ° C. or less), has high flexibility, is excellent in electrical insulation reliability, solder heat resistance, organic solvent resistance, flame resistance, and after curing. It is mentioned that the board warpage is small.

  Here, the present inventors have found that the insulating film of the present invention is excellent in various characteristics, but this is presumed to be due to the following reason.

By thermally curing the photosensitive thermosetting resin composition without exposure curing, the crosslink density of the insulating film decreases, the glass transition temperature (T _g ) decreases, and further, the uncured photosensitive resin becomes an insulating film. In order to act as a plasticizer, it is presumed that low warpage, flexibility, and crease resistance, which are difficult to achieve with an exposure-cured and heat-cured insulating film, have been achieved. Hereinafter, various components will be described in detail.

[(A) Base polymer]
The (A) base polymer used in the present invention is a compound that is soluble in an organic solvent and is formed by polymerization reaction of two or more monomers, and has a molecular weight of 1,000 or more and 1,000,000 or less. The polymer is not particularly limited as long as it is a polymer.

  Examples of the organic solvent include, but are not limited to, sulfoxide solvents such as dimethyl sulfoxide and diethyl sulfoxide, N, N-dimethylformamide, formamide solvents such as N, N-diethylformamide, N, N-dimethylacetamide, Examples thereof include acetamide solvents such as N, N-diethylacetamide, pyrrolidone solvents such as N-methyl-2-pyrrolidone and N-vinyl-2-pyrrolidone, hexamethylphosphoramide, and γ-butyrolactone. Further, if necessary, these organic polar solvents can be used in combination with an aromatic hydrocarbon such as xylene or toluene.

  Furthermore, for example, methyl monoglyme (1,2-dimethoxyethane), methyldiglyme (bis (2-methoxyether) ether), methyltriglyme (1,2-bis (2-methoxyethoxy) ethane), methyltetraglyme (Bis [2- (2-methoxyethoxyethyl)] ether), ethyl monoglyme (1,2-diethoxyethane), ethyldiglyme (bis (2-ethoxyethyl) ether), butyldiglyme (bis (2 Symmetric glycol diethers such as -butoxyethyl) ether), methyl acetate, ethyl acetate, isopropyl acetate, n-propyl acetate, butyl acetate, propylene glycol monomethyl ether acetate, ethylene glycol monobutyl ether acetate, diethylene glycol monoethyl ether Cetate (aka carbitol acetate, 2- (2-butoxyethoxy) ethyl acetate)), diethylene glycol monobutyl ether acetate, 3-methoxybutyl acetate, ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, dipropylene glycol methyl ether Acetates such as acetate, propylene glycol diacetate, 1,3-butylene glycol diacetate, dipropylene glycol methyl ether, tripropylene glycol methyl ether, propylene glycol n-propyl ether, dipropylene glycol n-propyl ether, propylene glycol n-butyl ether, dipropylene glycol n-butyl ether, tripylene glycol n Propyl ether, propylene glycol phenyl ether, dipropylene glycol dimethyl ether, 1,3-dioxolane, ethylene glycol monobutyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, ethers such solvents such as ethyl ether also ethylene glycol.

  The solubility of the organic solvent, which is an index that becomes soluble in the organic solvent, can be measured as a part by weight of the resin that dissolves in 100 parts by weight of the organic solvent and dissolves in 100 parts by weight of the organic solvent. If the weight part of resin is 5 weight part or more, it can be made soluble in an organic solvent. The organic solvent solubility measurement method is not particularly limited. For example, 5 parts by weight of the resin is added to 100 parts by weight of the organic solvent, stirred at 40 ° C. for 1 hour, cooled to room temperature, and left for 24 hours or more. It can measure by the method of confirming that it is a uniform solution without generation | occurrence | production of an insoluble matter and a precipitate.

  The weight average molecular weight of the (A) base polymer of the present invention can be measured, for example, by the following method.

(Weight average molecular weight measurement)
Equipment used: Tosoh HLC-8220GPC equivalent column: Tosoh TSK gel Super AWM-H (6.0 mm ID x 15 cm) x 2 guard columns: Tosoh TSK guard column Super AW-H
Eluent: 30 mM LiBr + 20 mM H3PO4 in DMF
Flow rate: 0.6 mL / min
Column temperature: 40 ° C
Detection conditions: RI: Polarity (+), response (0.5 sec)
Sample concentration: about 5 mg / mL
Standard product: PEG (polyethylene glycol)

  Controlling the weight average molecular weight within the above range is preferable because the resulting insulating film has excellent flexibility and chemical resistance. When the weight average molecular weight is 1,000 or less, flexibility and chemical resistance may decrease, and when the weight average molecular weight is 1,000,000 or more, the viscosity of the resin composition may increase.

  Examples of the polymerization reaction include chain polymerization, sequential polymerization, living polymerization, addition polymerization, polycondensation, addition condensation, radical polymerization, ionic polymerization, cationic polymerization, anionic polymerization, coordination polymerization, ring-opening polymerization, and copolymerization. It is done. Examples of the binder polymer obtained by such a polymerization reaction include, for example, polyurethane resins, poly (meth) acrylic resins, polyvinyl resins, polystyrene resins, polyethylene resins, polypropylene resins, polyimide resins. And polyamide resins, polyacetal resins, polycarbonate resins, polyester resins, polyphenylene ether resins, polyphenylene sulfide resins, polyether sulfone resins, polyether ether ketone resins, and the like.

[(B) Radical polymerizable compound]
The (B) radical polymerizable compound used in the present invention is a compound in which a chemical bond is formed by radicals generated by light or heat. Among them, (C) a compound in which a chemical bond is formed by a photopolymerization initiator, and a compound having at least one unsaturated double bond in the molecule is preferable. Furthermore, the unsaturated double bond is an acryl group (CH ₂ ═CH— group), a methacryloyl group (CH═C (CH ₃ ) — group) or a vinyl group (—CH═CH— group). Is preferred.

  Examples of the (2) radical polymerizable compound include bisphenol F EO modified (n = 2 to 50) diacrylate, bisphenol A EO modified (n = 2 to 50) diacrylate, and bisphenol S EO modified (n = 2 to 50). ) Diacrylate, bisphenol F EO modified (n = 2-50) dimethacrylate, bisphenol A EO modified (n = 2-50) dimethacrylate, bisphenol S EO modified (n = 2-50) dimethacrylate, 1,6- Hexanediol diacrylate, neopentyl glycol diacrylate, ethylene glycol diacrylate, pentaerythritol diacrylate, trimethylolpropane triacrylate, pentaerythritol triacrylate, dipentaerythritol hexaacrylate, Tramethylolpropane tetraacrylate, tetraethylene glycol diacrylate, 1,6-hexanediol dimethacrylate, neopentyl glycol dimethacrylate, ethylene glycol dimethacrylate, pentaerythritol dimethacrylate, trimethylolpropane trimethacrylate, pentaerythritol trimethacrylate, dipenta Erythritol hexamethacrylate, tetramethylolpropane tetramethacrylate, tetraethylene glycol dimethacrylate, methoxydiethylene glycol methacrylate, methoxypolyethylene glycol methacrylate, β-methacryloyloxyethyl hydrogen phthalate, β-methacryloyloxyethyl hydrogen succinate, 3-chloro 2-hydroxypropyl methacrylate, stearyl methacrylate, phenoxyethyl acrylate, phenoxydiethylene glycol acrylate, phenoxy polyethylene glycol acrylate, β-acryloyloxyethyl hydrogen succinate, lauryl acrylate, ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, Polyethylene glycol dimethacrylate, 1,3-butylene glycol dimethacrylate, 1,6-hexanediol dimethacrylate, neopentyl glycol dimethacrylate, polypropylene glycol dimethacrylate, 2-hydroxy-1,3-dimethacryloxypropane, 2,2 -Bis [4- (methacryloyl Ciethoxy) phenyl] propane, 2,2-bis [4- (methacryloxy / diethoxy) phenyl] propane, 2,2-bis [4- (methacryloxy / polyethoxy) phenyl] propane, polyethylene glycol diacrylate, tripropylene glycol diacrylate , Polypropylene glycol diacrylate, 2,2-bis [4- (acryloxydiethoxy) phenyl] propane, 2,2-bis [4- (acryloxypolyethoxy) phenyl] propane, 2-hydroxy-1-acryloxy-3- Methacryloxypropane, trimethylolpropane trimethacrylate, tetramethylol methane triacrylate, tetramethylol methane tetraacrylate, methoxydipropylene glycol methacrylate, methoxytri Tylene glycol acrylate, nonyl phenoxy polyethylene glycol acrylate, nonyl phenoxy polypropylene glycol acrylate, 1-acryloyloxypropyl-2-phthalate, isostearyl acrylate, polyoxyethylene alkyl ether acrylate, nonyl phenoxy ethylene glycol acrylate, polypropylene glycol dimethacrylate, 1, 4-butanediol dimethacrylate, 3-methyl-1,5-pentanediol dimethacrylate, 1,6-mexanediol dimethacrylate, 1,9-nonanediol methacrylate, 2,4-diethyl-1,5-pentanediol Dimethacrylate, 1,4-cyclohexanedimethanol dimethacrylate, dipropylene glycol diaquo Relate, tricyclodecane dimethanol diacrylate, 2,2-hydrogenated bis [4- (acryloxy polyethoxy) phenyl] propane, 2,2-bis [4- (acryloxy polypropoxy) phenyl] propane, 2,4 -Diethyl-1,5-pentanediol diacrylate, ethoxylated tomethylolpropane triacrylate, propoxylated tomethylolpropane triacrylate, isocyanuric acid tri (ethane acrylate), pentathritol tetraacrylate, ethoxylated pentathritol tetraacrylate, Propoxylated pentathritol tetraacrylate, ditrimethylolpropane tetraacrylate, dipentaerythritol polyacrylate, triallyl isocyanurate, glycidyl methacrylate, Sidyl allyl ether, 1,3,5-triacryloylhexahydro-s-triazine, triallyl 1,3,5-benzenecarboxylate, triallylamine, triallyl citrate, triallyl phosphate, alloverbital, diallylamine, diallyldimethylsilane , Diallyl disulfide, diallyl ether, zalyl sialate, diallyl isophthalate, diallyl terephthalate, 1,3-dialyloxy-2-propanol, diallyl sulfide diallyl maleate, 4,4′-isopropylidene diphenol dimethacrylate, 4,4 ′ -Isopropylidene diphenol diacrylate and the like are preferred, but not limited thereto. In particular, the repeating unit of EO (ethylene oxide) contained in one molecule of diacrylate or methacrylate is preferably in the range of 2-50, more preferably 2-40. By using an EO repeating unit in the range of 2 to 50, the solubility of the resin composition in an aqueous developer typified by an alkaline aqueous solution is improved, and the development time is shortened. Furthermore, it is difficult for stress to remain in the insulating film obtained by curing the photosensitive thermosetting resin composition. For example, among printed wiring boards, printed wiring boards are laminated on a flexible printed wiring board based on polyimide resin. The curl can be suppressed.

  In particular, it is particularly preferable to use the EO-modified diacrylate or dimethacrylate together with an acrylic resin having 3 or more acrylic groups or methacrylic groups in order to improve developability. For example, ethoxylated isocyanuric acid EO-modified triacrylate, Ethoxylated isocyanuric acid EO modified trimethacrylate, ethoxylated trimethylolpropane triacrylate, ethoxylated trimethylolpropane triacrylate, ethoxylated trimethylolpropane triacrylate, trimethylolpropane triacrylate, propoxylated trimethylolpropane triacrylate, pentaerythritol tri Acrylate, ethoxylated pentaerythritol tetraacrylate, ethoxylated pentaerythritol tetraacrylate, ditrimethyl Propanetetraacrylate, ditrimethylolpropane tetraacrylate, propoxylated pentaerythritol tetraacrylate, pentaerythritol tetraacrylate, dipentaerythritol hexaacrylate, 2,2,2-trisacryloyloxymethyl ethyl succinic acid, 2,2, 2-trisacryloyloxymethylethylphthalic acid, propoxylated ditrimethylolpropane tetraacrylate, propoxylated dipentaerythritol hexaacrylate, ethoxylated isocyanuric acid triacrylate, ε-caprolactone modified tris- (2-acryloxyethyl) isocyanurate, Caprolactone-modified ditrimethylolpropane tetraacrylate, the following general formula (1)

(Wherein a + b = 6 and n = 12.), A compound represented by the following general formula (2)

(Wherein a + b = 4 and n = 4), a compound represented by the following formula (3)

A compound represented by the following general formula (4)

(Where m = 1, a = 2, b = 4, or m = 1, a = 3, b = 3, or m = 1, a = 6, b = 0, or m = 2, a = 6 B = 0)), a compound represented by the following general formula (5)

(Wherein a + b + c = 3.6), a compound represented by the following formula (6)

A compound represented by the following general formula (7)

An acrylic resin such as a compound represented by the formula (where m · a = 3, a + b = 3, where “m · a” is a product of m and a) is preferably used.

  In addition, hydroxyl groups, carbonyls in the molecular structure such as 2-hydroxy-3-phenoxypropyl acrylate, phthalic acid monohydroxyethyl acrylate, ω-carboxy-polycaprolactone monoacrylate, acrylic acid dimer, pentaerythritol tri and tetraacrylate Those having a group are also preferably used.

  In addition, any radically polymerizable compound such as an epoxy-modified acrylic (methacrylic) resin, a urethane-modified acrylic (methacrylic) resin, or a polyester-modified acrylic (methacrylic) resin may be used.

  In addition, although it is also possible to use 1 type as a radically polymerizable compound, using 2 or more types together is preferable when improving the heat resistance of the insulating film after photocuring.

  The radically polymerizable compound in the present invention is blended so as to be 10 to 200 parts by weight with respect to 100 parts by weight in total of the components (A), (C), (D) and other components. Is preferable in terms of improving the photosensitivity of the photosensitive resin composition.

  When the amount of the radical polymerizable compound is less than the above range, the alkali resistance of the insulating film is lowered, and it may be difficult to obtain contrast when exposed and developed. In addition, when the amount of the radical polymerizable resin is larger than the above range, productivity decreases because the stickiness of the coating film obtained by applying the photosensitive resin composition on the substrate and drying the solvent increases. In addition, when the crosslinking density becomes too high, the insulating film may be brittle and easily cracked. By making it within the above range, the resolution at the time of exposure / development can be set to an optimum range.

[(C) Photopolymerization initiator]
The photopolymerization initiator in the present invention is a compound that is activated by energy such as exposure to start and accelerate the photopolymerization reaction. Examples of such photopolymerization initiators include Michler's ketone, 4,4′-bis (diethylamino) benzophenone, 4,4 ′, 4 ″ -tris (dimethylamino) triphenylmethane, and 2,2′-bis ( 2-chlorophenyl) -4,4 ′, 5,5′-tetraphenyl-1,2′-diimidazole, acetophenone, benzoin, 2-methylbenzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether -Tell, benzoin isobutyl ether, 2-t-butylanthraquinone, 1,2-benzo-9,10-anthraquinone, methylanthraquinone, thioxanthone, 2,4-diethylthioxanthone, 2-isopropylthioxanthone, 1-hydroxycyclohexylphenyl Ketone, diacetylbenzyl, benzyldimethylketa , Benzyldiethylketal, 2 (2′-furylethylidene) -4,6-bis (trichloromethyl) -S-triazine, 2 [2 ′ (5 ″ -methylfuryl) ethylidene] -4,6- Bis (trichloromethyl) -S-triazine, 2 (p-methoxyphenyl) -4,6-bis (trichloromethyl) -S-triazine, 2,6-di (p-azidobenzal) -4-methylcyclohexanone, 4, 4'-diazidochalcone, di (tetraalkylammonium) -4,4'-diazidostilbene-2,2'-disulfonate, 2,2-dimethoxy-1,2-diphenylethane-1-one, 1 -Hydroxy-cyclohexyl-phenyl-ketone, 2-hydroxy-2-methyl-1-phenyl-propan-1-one, 1- [4- (2-hydroxyethoxy) -pheny ] -2-Hydroxy-2-methyl-1-propan-1-one, 2-methyl-1- [4- (methylthio) phenyl] -2-morpholinopropan-1-one, 2-benzyl-2-dimethyl Amino-1- (4-morpholinophenyl) -butane-1, bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide, bis (2,6-dimethoxybenzoyl) -2,4,4-trimethyl -Pentylphosphine oxide, 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide, 2-hydroxy-2-methyl-1-phenyl-propane-1-ketone, bis (n5-2,4-cyclopentadiene- 1-yl) -bis (2,6-difluoro-3- (1H-pyrrol-1-yl) -phenyl) titanium, 1,2-octa Dione, 1- [4- (phenylthio)-, 2- (O-benzoyloxime)], iododium, (4-methylphenyl) [4- (2-methylpropyl) phenyl] -hexafluorophosphate (1 -), Ethyl-4-dimethylaminobenzoate, 2-ethylhexyl-4-dimethylaminobenzoate, ethanone, 1- [9-ethyl-6- (2-methylbenzoyl) -9H-carbazol-3-yl]-, 1 -(O-acetyloxyome) etc. are mentioned. The photopolymerization initiator is preferably selected as appropriate, and it is desirable to use a mixture of one or more.

  The photoinitiator in this invention is mix | blended so that it may become 0.1-50 weight part with respect to a total of 100 weight part of (A) component, (B) component, (C) component, and another component. It is preferable.

  Since the photosensitivity of a resin composition improves by making it the said mixture ratio, it is preferable.

  When the photopolymerization initiator component is less than the above range, the reaction of the radical polymerizable group at the time of light irradiation hardly occurs and the curing is often insufficient. Moreover, when there are more photoinitiator components than the said range, adjustment of light irradiation amount becomes difficult and may be in an overexposed state. Therefore, in order to advance the photocuring reaction efficiently, it is preferable to adjust within the above range.

[(D) Thermosetting resin]
The (D) thermosetting resin in the present invention is a compound that generates a crosslinked structure by heating and functions as a thermosetting agent. For example, thermosetting resins such as epoxy resin, bismaleimide resin, bisallyl nadiimide resin, acrylic resin, methacrylic resin, hydrosilyl cured resin, allyl cured resin, unsaturated polyester resin; A side chain reactive group type thermosetting polymer having a reactive group such as a group, a vinyl group, an alkoxysilyl group, and a hydrosilyl group can be used. These can be used alone or in combination of two or more.

  Among these, as (D) thermosetting resin in this invention, it is preferable to use an epoxy resin. The epoxy resin in the present invention includes all monomers, oligomers, polymers, etc., regardless of molecular weight, as long as it has at least one epoxy group in the molecule. It is a compound that functions as an agent. By containing an epoxy resin, heat resistance can be imparted to an insulating film obtained by curing the resin composition, and adhesion to a conductor such as a metal foil or a circuit board can be imparted. The epoxy resin is a compound containing at least two epoxy groups in the molecule. For example, as a bisphenol A type epoxy resin, product names jER828, jER1001, jER1002, and ADEKA manufactured by Japan Epoxy Resin Co., Ltd. Trade names of Adeka Resin EP-4100E, Adeka Resin EP-4300E, trade names RE-310S and RE-410S manufactured by Nippon Kayaku Co., Ltd., trade names Epicron 840S, Epicron 850S, Epicron 1050 and Epicron 7050 manufactured by Dainippon Ink, Inc. The product names Epototo YD-115, Epototo YD-127, Epototo YD-128, and bisphenol F type epoxy resins manufactured by Toto Kasei Co., Ltd. are trade names jER806 and jER8 manufactured by Japan Epoxy Resin Co., Ltd. 7. Trade names Adeka Resin EP-4901E, Adeka Resin EP-4930, Adeka Resin EP-4950 manufactured by Adeka Co., Ltd., trade names RE-303S, RE-304S, RE-403S, RE-404S, DIC manufactured by Nippon Kayaku Co., Ltd. Product names Epicron 830 and Epicron 835 manufactured by Co., Ltd. Product names Epototo YDF-170, Epototo YDF-175S, Epototo YDF-2001, and Bisphenol S type epoxy resin manufactured by Toto Kasei Co., Ltd. As Epiklon EXA-1514 and hydrogenated bisphenol A type epoxy resin, trade names jERYX8000, jERYX8034, jERYL7170, and ADEKA RESIN EP-408 manufactured by ADEKA Corporation are available. E, DIC Corporation trade name Epicron EXA-7015, Toto Kasei Co., Ltd. trade name Epototo YD-3000, Epototo YD-4000D, biphenyl type epoxy resin, Japan Epoxy Resin Corporation trade name jERYX4000, jERYL6121H, jERYL6640, jERYL6667, Nippon Kayaku Co., Ltd. trade name NC-3000, NC-3000H, phenoxy type epoxy resin, Japan Epoxy Resin Co., Ltd. trade name jER1256, jER4250, jER4275, naphthalene type epoxy resin Are DIC Corporation trade names Epicron HP-4032, Epicron HP-4700, Epicron HP-4200, Nippon Kayaku Co., Ltd. trade names NC-7000L, Phenol As the borak type epoxy resin, trade names jER152 and jER154 manufactured by Japan Epoxy Resin Co., Ltd., trade names EPPN-201-L manufactured by Nippon Kayaku Co., Ltd., trade names Epicron N-740 manufactured by DIC Corporation, and Epicron N- 770, product names Epototo YDPN-638 manufactured by Tohto Kasei Co., Ltd., and cresol novolak type epoxy resins include product names EOCN-1020, EOCN-102S, EOCN-103S, EOCN-104S, DIC shares manufactured by Nippon Kayaku Co., Ltd. Brand names EPIKRON N-660, Epicron N-670, Epicron N-680, Epicron N-695, and trisphenol methane type epoxy resins manufactured by the company include trade names EPPN-501H and EPPN-501HY manufactured by Nippon Kayaku Co., Ltd. EPPN-502H, As the cyclopentadiene type epoxy resin, trade name XD-1000 manufactured by Nippon Kayaku Co., Ltd., the product name Epicron HP-7200 manufactured by DIC Co., Ltd., and as the amine type epoxy resin, trade name Epototo YH- of Toto Kasei Co., Ltd. 434, Epototo YH-434L, as flexible epoxy resin, trade names jER871, jER872, jERYL7175, jERYL7217, manufactured by Japan Epoxy Resin Co., Ltd., trade name Epicron EXA-4850, manufactured by DIC Corporation, and urethane-modified epoxy resin Adeka Resin EPU-6, Adeka Resin EPU-73, Adeka Resin EPU-78-11, Adeka Resin EPR-4023, Adeka Resin EPR-4023, Adeka Resin Resin EPR-4026, Adeka Resin EPR-1309, as a chelate-modified epoxy resin, ADEKA Corporation under the trade name Adeka Resin EP-49-10, and the like Adecaresin EP-49-20. These can be used alone or in combination of two or more.

  Although it does not specifically limit as a hardening | curing agent of the epoxy resin in this invention, For example, phenol resins, such as a phenol novolak resin, a cresol novolak resin, a naphthalene type phenol resin, an amino resin, a urea resin, a melamine, a dicyandiamide, etc. It can be used alone or in combination of two or more.

  Further, the curing accelerator is not particularly limited, but for example, phosphine compounds such as triphenylphosphine; amine compounds such as tertiary amine, trimethanolamine, triethanolamine and tetraethanolamine; 1,8- Borate compounds such as diaza-bicyclo [5,4,0] -7-undecenium tetraphenylborate, imidazole, 2-ethylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 2-un Imidazoles such as decylimidazole, 1-benzyl-2-methylimidazole, 2-heptadecylimidazole, 2-isopropylimidazole, 2,4-dimethylimidazole, 2-phenyl-4-methylimidazole; 2-methylimidazoline, 2- Ethyl imidazoline, 2 Imidazolines such as isopropylimidazoline, 2-phenylimidazoline, 2-undecylimidazoline, 2,4-dimethylimidazoline, 2-phenyl-4-methylimidazoline; 2,4-diamino-6- [2′-methylimidazolyl- ( 1 ′)]-ethyl-s-triazine, 2,4-diamino-6- [2′-undecylimidazolyl- (1 ′)]-ethyl-s-triazine, 2,4-diamino-6- [2 ′ Examples include azine-based imidazoles such as -ethyl-4'-methylimidazolyl- (1 ')]-ethyl-s-triazine, and these can be used alone or in combination of two or more.

  The (D) thermosetting resin component in the present invention is preferably 0.5 to 100 parts by weight, more preferably 1 to 100 parts by weight in total of the components (A) to (C) and other components. -50 parts by weight, particularly preferably 5-20 parts by weight. By adjusting the amount of the thermosetting resin component within the above range, it is preferable because the heat resistance, chemical resistance and electrical insulation reliability of the insulating film obtained by curing the resin composition can be improved.

  If the thermosetting resin component is less than the above range, the insulating film obtained by curing the resin composition may be inferior in heat resistance and electrical insulation reliability. Moreover, when there are more thermosetting resin components than the said range, the insulating film obtained by hardening a resin composition becomes weak, it is inferior to a softness | flexibility, and the curvature of an insulating film may also become large.

[Other ingredients]
In addition to (A) base polymer, (B) radical polymerizable compound, (C) photopolymerization initiator, and (D) thermosetting resin, the photosensitive thermosetting resin composition in the present invention is used as necessary. You may contain additives, such as a filler, a flame retardant, a coloring agent, an adhesion imparting agent, a polymerization inhibitor, and an organic solvent.

  The filler used in the present invention is not particularly limited as long as the filler is an organic filler, inorganic filler, organic-organic composite fine particles, and organic-inorganic composite fine particles, but the shape is spherical or powdery. , Fibers, needles, scales and the like. Examples of the organic filler include polyethylene, benzoguanamine, melamine, phthalocyanine powder and the like, as well as a multi-layered core shell using silicone, acrylic, styrene butadiene rubber, butadiene rubber, and the like. Examples of the inorganic filler include silica, titanium oxide, alumina, silicon nitride, boron nitride, calcium carbonate, calcium hydrogen phosphate, calcium phosphate, and mica. These can be used alone or in combination of two or more. Various fillers may be added for the purpose of controlling other characteristics such as slidability, thermal conductivity, conductivity, corona resistance, and loop stiffness.

  Further, the average particle diameter of the filler is particularly preferably from 0.1 μm to 25 μm. Below this range, the modification effect by the filler hardly appears, and further the dispersibility and the stability of the dispersion may be significantly impaired. On the other hand, if it exceeds this range, the patterning property and the mechanical properties of the insulating film may be greatly impaired.

  The filler is added in an amount of 0.01 to 50 parts by weight, preferably 1 to 30 parts by weight, more preferably 5 to 20 parts by weight, based on a total of 100 parts by weight of the components other than the filler in the insulating film of the present invention. Part. If the amount of filler added is less than this range, the effect of modification by the filler hardly appears, and if it exceeds this range, the mechanical properties of the insulating film may be greatly impaired.

The method of adding filler is
1. 1. A method of adding to a polymerization reaction solution before or during polymerization 2. A method of kneading fillers using three rolls after the completion of polymerization. Any method such as a method of preparing a dispersion containing a filler and mixing it with a resin composition solution may be used. The filler is preferably selected as appropriate, and one or more fillers can be mixed and used. Further, in order to disperse the filler satisfactorily and stabilize the dispersion state, a dispersant, a thickener and the like can be used within a range not affecting the film physical properties.

  The flame retardant in the present invention is a compound used to make an insulating film flame retardant. For example, a phosphoric ester compound, a halogen-containing compound, a metal hydroxide, an organic phosphorus compound, a silicone, or the like can be used, and the method of use can be used as an additive flame retardant or a reactive flame retardant. . Moreover, you may use a flame retardant suitably combining 1 type (s) or 2 or more types. Among these, as the flame retardant, it is more preferable to use a non-halogen compound from the viewpoint of environmental pollution, and a phosphorus flame retardant is particularly preferable.

  Moreover, it is preferable that the addition amount of a flame retardant mix | blends so that it may become 1-100 weight part with respect to a total of 100 weight part of components other than the flame retardant in the insulating film of this invention. The flame retardance is improved without impairing the folding resistance of the insulating film obtained by the above blending ratio, which is preferable. When there are few flame retardant components than the said range, the flame retardance of an insulating film may become inadequate.

  As colorants in the present invention, phthalocyanine compounds, azo compounds, carbon black, titanium oxide, adhesion imparting agents, silane coupling agents, triazole compounds, tetrazole compounds, triazine compounds, polymerization inhibitors These include hydroquinone, hydroquinone monomethyl ether and the like, and these can be used alone or in combination of two or more.

  The solvent in the present invention may be any solvent that can dissolve the resin composition components. For example, sulfoxide solvents such as dimethyl sulfoxide and diethyl sulfoxide, methyl monoglyme (1,2-dimethoxyethane), methyl diglyme (bis (2-methoxyether) ether), methyl triglyme (1,2-bis (2) -Methoxyethoxy) ethane), methyltetraglyme (bis [2- (2-methoxyethoxyethyl)] ether), ethyl monoglyme (1,2-diethoxyethane), ethyldiglyme (bis (2-ethoxyethyl)) Ether), symmetric glycol diethers such as butyl diglyme (bis (2-butoxyethyl) ether), γ-butyrolactone, methyl acetate, ethyl acetate, isopropyl acetate, n-propyl acetate, butyl acetate, propylene glycol monomethyl ether acetate , Et Glycol monobutyl ether acetate, diethylene glycol monoethyl ether acetate (also known as carbitol acetate, 2- (2-butoxyethoxy) ethyl acetate), diethylene glycol monobutyl ether acetate, 3-methoxybutyl acetate, ethylene glycol monomethyl ether acetate, ethylene glycol Acetates such as monoethyl ether acetate, dipropylene glycol methyl ether acetate, propylene glycol diacetate, 1,3-butylene glycol diacetate, dipropylene glycol methyl ether, tripropylene glycol methyl ether, propylene glycol n-propyl ether, Dipropylene glycol n-propyl ether, propylene glycol n -Butyl ether, dipropylene glycol n-butyl ether, tripylene glycol n-propyl ether, propylene glycol phenyl ether, dipropylene glycol dimethyl ether, 1,3-dioxolane, ethylene glycol monobutyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, ethylene glycol Examples include ethers such as monoethyl ether, and these can be used alone or in combination of two or more. The amount of the solvent in the present invention is preferably 10 to 400 parts by weight, more preferably 20 to 200 parts by weight, particularly preferably based on 100 parts by weight of the total components other than the solvent in the photosensitive thermosetting resin composition. Is 40 to 100 parts by weight. It is preferable to adjust the amount of the solvent within the above range because the viscosity and viscosity of the resin composition can be adjusted within a range suitable for coating such as screen printing. When the solvent is less than the above range, the viscosity of the resin composition becomes very high, coating becomes difficult, and foam entrainment during coating and leveling properties may be inferior. Moreover, when there are more solvents than the said range, the viscosity of a resin composition will become very low, application | coating will become difficult and the circuit coverage may be inferior.

[Method for Forming First Location and Second Location on the Same Flexible Printed Circuit Board]
Hereinafter, a method for forming the first location A and the second location B (see FIG. 1) on the same flexible printed wiring board of the present invention will be described in detail with reference to the drawings. At least one flexible print On the wiring board 2, there is a first location A that is exposed and cured by heat, and a second location B that is cured without being exposed and cured, and the first location A and the second location B are present. If it is obtained from the same photosensitive thermosetting resin composition 1, it will not specifically limit.

[Method of forming an insulating film by thermally curing the first location A and the second location B after the first location A is exposed and cured] (see FIG. 2)
<Step 1>
The photosensitive thermosetting resin composition 1 is applied to the flexible printed wiring board 2 and dried. Application to the flexible printed wiring board 2 can be performed by screen printing, curtain roll, river roll, spray coating, spin coating using a spinner, or the like. Drying of the coating film (preferably thickness: 5 to 100 μm, particularly 10 to 100 μm) is performed at 120 ° C. or less, preferably 40 to 100 ° C.

<Step 2>
A negative-type photomask 3 is placed on the dried coating film, and exposure and curing is performed by irradiating actinic rays 4 such as ultraviolet rays, visible rays, and electron beams.

<Step 3>
The negative photomask 3 is removed, and the second portion B is masked with the polyimide tape 6. At this time, the material used for the mask of the second portion B is not particularly limited as long as the second portion B can be protected from development <Step 4>, but in <Step 5>, it is peeled off without damaging the coating film surface. What can do is preferable.

<Step 4>
The unexposed portion is developed with a developer using various methods such as shower, paddle, immersion, or ultrasonic wave. Since the time until the pattern is exposed varies depending on the spraying pressure and flow rate of the developing device and the temperature of the etching solution, it is desirable to find the optimum device conditions as appropriate.

  As the developer, an alkaline aqueous solution is preferably used. This developer may contain a water-soluble organic solvent such as methanol, ethanol, n-propanol, isopropanol, or N-methyl-2-pyrrolidone. Examples of the alkaline compound that gives the alkaline aqueous solution include hydroxides, carbonates, hydrogen carbonates, amine compounds, and the like of alkali metals, alkaline earth metals, or ammonium ions, specifically sodium hydroxide. , Potassium hydroxide, ammonium hydroxide, sodium carbonate, potassium carbonate, ammonium carbonate, sodium bicarbonate, potassium bicarbonate, ammonium bicarbonate, tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetraisopropylammonium Hydroxide, N-methyldiethanolamine, N-ethyldiethanolamine, N, N-dimethylethanolamine, triethanolamine, triisopropanolamine, triisopro Etc. can be mentioned triethanolamine, aqueous solution with compounds of other long as it exhibits basicity can also be naturally used. Further, the temperature of the developer depends on the composition of the resin composition and the composition of the alkaline developer, and is generally 0 ° C. or higher and 80 ° C. or lower, more generally 10 ° C. or higher and 60 ° C. or lower. It is preferable to do.

  The fine opening formed by the development process is rinsed to remove unnecessary residues. Examples of the rinsing liquid include water and acidic aqueous solutions.

  Here, the first portion A in the insulating film of the flexible printed wiring board is patterned by alkali development or the like.

<Step 5>
The polyimide tape 6 that has masked the second portion B is peeled off. At this time, it may be coated as long as it does not affect the characteristics of the manufactured flexible printed wiring board, or the polyimide tape 6 masked after the thermosetting <Step 6> is removed. Also good.

<Step 6>
Hot air 8 is applied to the first location A and the second location B to perform thermosetting. By performing thermosetting, an insulating film having excellent heat resistance and chemical resistance can be obtained. Although the thickness of an insulating film is determined in consideration of the thickness of a flexible printed wiring board, etc., it is preferable that it is about 2-50 micrometers. The final heat treatment temperature at this time is preferably 100 ° C. or more and 250 ° C. or less, more preferably 120 ° C. or more and 200 ° C. for the purpose of preventing the oxidation of the wiring and the like and not reducing the adhesion with the flexible printed wiring board. It is below, Especially preferably, they are 130 degreeC or more and 180 degrees C or less. When the heat treatment temperature increases, the oxidative deterioration of the wiring or the like progresses, and the adhesion with the substrate may decrease.

  Here, it has the 1st location by which exposure hardening and thermosetting were carried out, and the 2nd location by which heat curing was carried out without exposure hardening, and the 1st location and the 2nd location are the same photosensitive thermosetting. A flexible printed wiring board having an insulating film obtained from the conductive resin composition is manufactured.

[Method for forming an insulating film by thermally curing the first location A and then thermally curing the first location A and the second location B after the second location B is thermally cured] ( (See Figure 3)
<Step 1>
The photosensitive thermosetting resin composition 1 is applied to the flexible printed wiring board 2 and dried. Application to the flexible printed wiring board 2 can be performed by screen printing, curtain roll, river roll, spray coating, spin coating using a spinner, or the like. Drying of the coating film (preferably thickness: 5 to 100 μm, particularly 10 to 100 μm) is performed at 120 ° C. or less, preferably 40 to 100 ° C.

<Step 2>
The second location B is thermoset. At this time, it is desirable that the solubility of the unexposed portion of the first portion A is not impaired, and the second portion B is heat-cured within a range not developed in the development <Step 4>. As such a thermosetting method, for example, a method of thermosetting with warm air such as a dryer or a heat gun, a Teflon (registered trademark) sheet is placed on the surface of the dried coating film, and a heated metal is brought into contact with the heat curing. There are methods. Moreover, in order to prevent the thermosetting of the 1st location A, you may protect the 1st location A with a heat sink.

<Step 3>
A negative-type photomask 3 is placed on the dried coating film, and exposure and curing is performed by irradiating actinic rays 4 such as ultraviolet rays, visible rays, and electron beams.

<Step 4>
The negative photomask 3 is removed, and the unexposed portion is developed with a developer using various methods such as shower, paddle, immersion, or ultrasonic wave. Since the time until the pattern is exposed varies depending on the spraying pressure and flow rate of the developing device and the temperature of the etching solution, it is desirable to find the optimum device conditions as appropriate.

  As the developer, an alkaline aqueous solution is preferably used. This developer may contain a water-soluble organic solvent such as methanol, ethanol, n-propanol, isopropanol, or N-methyl-2-pyrrolidone. Examples of the alkaline compound that gives the alkaline aqueous solution include hydroxides, carbonates, hydrogen carbonates, amine compounds, and the like of alkali metals, alkaline earth metals, or ammonium ions, specifically sodium hydroxide. , Potassium hydroxide, ammonium hydroxide, sodium carbonate, potassium carbonate, ammonium carbonate, sodium bicarbonate, potassium bicarbonate, ammonium bicarbonate, tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetraisopropylammonium Hydroxide, N-methyldiethanolamine, N-ethyldiethanolamine, N, N-dimethylethanolamine, triethanolamine, triisopropanolamine, triisopro Etc. can be mentioned triethanolamine, aqueous solution with compounds of other long as it exhibits basicity can also be naturally used. Further, the temperature of the developer depends on the composition of the resin composition and the composition of the alkaline developer, and is generally 0 ° C. or higher and 80 ° C. or lower, more generally 10 ° C. or higher and 60 ° C. or lower. It is preferable to do.

  The fine opening formed by the development process is rinsed to remove unnecessary residues. Examples of the rinsing liquid include water and acidic aqueous solutions.

  Here, the first portion A in the insulating film of the flexible printed wiring board is patterned by alkali development or the like.

  Further, since the solubility of the unexposed portion of the first location A is not impaired and the second location B is thermally cured in a range not developed in development <Step 4>, unlike the previous method, It is not necessary to mask the second portion B, which is an unexposed portion, using a polyimide tape or the like.

<Step 5>
Hot air 8 is applied to the first location A and the second location B to perform thermosetting. By performing thermosetting, an insulating film having excellent heat resistance and chemical resistance can be obtained. Although the thickness of an insulating film is determined in consideration of the thickness of a flexible printed wiring board, etc., it is preferable that it is about 2-50 micrometers. The final heat treatment temperature at this time is preferably 100 ° C. or more and 250 ° C. or less, more preferably 120 ° C. or more and 200 ° C. for the purpose of preventing the oxidation of the wiring and the like and not reducing the adhesion with the flexible printed wiring board. It is below, Especially preferably, they are 130 degreeC or more and 180 degrees C or less. When the heat treatment temperature increases, the oxidative deterioration of the wiring or the like progresses, and the adhesion with the substrate may decrease.

  Here, it has the 1st location by which exposure hardening and thermosetting were carried out, and the 2nd location by which heat curing was carried out without exposure hardening, and the 1st location and the 2nd location are the same photosensitive thermosetting. A flexible printed wiring board having an insulating film obtained from the conductive resin composition is manufactured.

  EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited to these examples.

<Synthesis of base polymer>
(Synthesis Example 1)
In a separable flask equipped with a stirrer, a thermometer, a dropping funnel, a reflux tube and a nitrogen introduction tube, 17.5 g of 1,2-bis (2-methoxyethoxy) ethane was charged as a polymerization solvent, and then norbornene diisocyanate ( (Molecular weight: 206.4 g) 20.6 g was charged and dissolved by heating to 80 ° C. To this solution, 50.0 g of polycarbonate diol (manufactured by Asahi Kasei Corporation: trade name PCDL T5652, average molecular weight 2000) and 8.1 g of dimethylolbutanoic acid (molecular weight: 148.2 g) were added 1,2-bis (2-methoxyethoxy). ) A solution dissolved in 50.0 g of ethane was added over 1 hour, followed by heating under reflux for 5 hours to obtain an intermediate. Thereafter, 1 g of methanol was added and stirred for 5 hours to obtain a solution containing 50% by weight of a polyurethane resin having a weight average molecular weight of 10,000.

<Preparation of photosensitive thermosetting resin composition>
(A) A base polymer, (B) a radical polymerizable compound, (C) a photopolymerization initiator, and (D) a thermosetting resin and other components were added to prepare a photosensitive resin composition. Table 1 shows the blending amount of each constituent raw material in the resin solid content and the kind of the raw material. In addition, 1,2-bis (2-methoxyethoxy) ethane which is a solvent in the table is the total amount of solvent including the solvent and the like contained in the resin solution synthesized in the above synthesis example. The following evaluation was carried out by completely defoaming the foam in the solution with a defoaming device.

The photosensitive thermosetting resin composition is coated with the photosensitive thermosetting resin composition prepared on the surface of a polyimide film having a thickness of 25 μm (Akane 25NPI manufactured by Kaneka Corporation) in an oven at 80 ° C. Then, a negative mask with a line width / space width = 100/100 μm is placed, and the entire surface is exposed to ultraviolet rays with an integrated exposure amount of 300 mJ / cm ² and exposed to 1% by weight of carbonic acid at 30 ° C. After developing with an aqueous sodium solution for 90 seconds, the surface of the insulating film obtained by thermosetting in an oven at 150 ° C. for 30 minutes is observed, and a photosensitive pattern of line width / space width = 100/100 μm is obtained. It was drawn, and it was observed that there was no fluctuation of the line due to peeling of the line part, and there was no undissolved residue in the space part.

<1> Product name of radically polymerizable compound (urethane-modified epoxy (meth) acrylate, solid content acid value 97.7 mgKOH / g) manufactured by Nippon Kayaku Co., Ltd. <2> Radical polymerizable compound (EO) manufactured by Hitachi Chemical Co., Ltd. Product name of modified bisphenol A dimethacrylate, solid content acid value of 0.11 mg KOH / g) <3> Product name of photopolymerization initiator manufactured by BASF Japan Co., Ltd. <4> Bisphenol A type epoxy resin manufactured by Japan Epoxy Resin Co., Ltd. (epoxy) Product name <5> made by Nippon Aerosil Co., Ltd. product name <6> made by Ciba Japan Co., Ltd. product name <7> product made by Kyoeisha Chemical Co., Ltd.

Example 1
<Method for forming an insulating film by thermally curing the first location and the second location after the first location is exposed and cured>
The above-mentioned photosensitive thermosetting resin composition is applied onto a comb-shaped flexible printed wiring board using a baker type applicator so that the dry thickness on the copper foil is 20 μm, and then in an oven at 80 ° C. Dry for 20 minutes.

  The comb-shaped flexible circuit board has a line width / space width = 100 μm / 100 μm after a 12 μm thick copper foil is bonded to a polyimide film (Apical 25 NPI) manufactured by Kaneka Corporation with a polyimide-based adhesive. After being immersed in a 10% by volume sulfuric acid aqueous solution for 1 minute, the one prepared by copper etching was washed with pure water and subjected to a copper foil surface treatment.

Next, a negative mask was placed so that half of the dried coating film on the copper wiring could be exposed, and exposure was performed by irradiating the entire surface with ultraviolet rays of an integrated exposure amount of 300 mJ / cm ² . Thereafter, a polyimide tape was attached to the remaining half, and development was performed with a 1 wt% sodium carbonate aqueous solution at 30 ° C. for 90 seconds. Thereafter, the polyimide tape was peeled off and heat-cured in an oven at 150 ° C. for 30 minutes. (See FIG. 4).

(Example 2)
<The method of forming an insulating film by thermally curing the first location and then curing the first location and the second location after thermally curing the second location>
In the same manner as in Example 1, the photosensitive thermosetting resin composition was applied onto a comb-shaped flexible printed wiring board using a Baker-type applicator so that the dry thickness on the copper foil was 20 μm, and then And dried in an oven at 80 ° C. for 20 minutes.

  Next, a Teflon (registered trademark) sheet was placed on one half of the dried coating film on the copper wiring, and heat-cured for 30 minutes using a silicon rubber heater so that the temperature of the coating film surface was 160 ° C. The temperature of the coating surface was measured using a thermocouple.

After that, a negative mask is placed so that the remaining half of the coating film on the copper wiring can be exposed, and the entire surface is exposed by irradiating with an ultraviolet ray of an integrated exposure amount of 300 mJ / cm ² , and a 1 wt% sodium carbonate aqueous solution at 30 ° C. The film was developed for 90 seconds at 150 ° C. and then thermally cured in an oven at 150 ° C. for 30 minutes.

  The evaluation of Examples 1 and 2 was performed as follows, and the results are shown in Table 2.

(I) Insulation reliability Applying 100V DC current to both terminals of the test piece in the 85 ° C and 85% RH environmental test machine, the insulation resistance value changes and migration occurs. Observed.
○: A resistance value of 10 8 or more in 1000 hours after the start of the test, and no occurrence of migration or dendrite.
X: Migration, dendrite, etc. occurred in 1000 hours after the start of the test.

(Ii) Flexibility The second portion of the produced insulating film was bent 10 times at 180 ° perpendicular to the comb pattern, and the coating film was visually confirmed to check for cracks. (See Figure 5.)
○: There is no crack in the insulating film.
X: The insulating film has a crack.

(Iii) Solvent resistance The produced insulating film was immersed in methyl ethyl ketone at 25 ° C. for 15 minutes and then air-dried, and the state of the film surface was observed.
○: There is no abnormality in the coating film.
X: Abnormality such as swelling or peeling occurs in the coating film.

(Comparative Example 1)
<Method of forming an insulating film by thermally curing the entire surface after exposing and curing the entire surface>
In the same manner as in Example 1, the photosensitive thermosetting resin composition was applied on a comb-shaped flexible printed wiring board using a Baker type applicator so that the dry thickness on the copper foil was 20 μm, and then 80 Dry in an oven at 20 ° C. for 20 minutes.

Next, the entire surface of the dried coating film on the copper wiring was exposed to 300 mJ / cm ² of an ultraviolet ray with an integrated exposure amount. Thereafter, development was performed with a 1 wt% sodium carbonate aqueous solution at 30 ° C. for 90 seconds, followed by thermal curing in an oven at 150 ° C. for 30 minutes.

(Comparative Example 2)
<Method of forming an insulating film by thermally curing the entire surface and then exposing and curing the entire surface>
In the same manner as in Example 1, the photosensitive thermosetting resin composition was applied on a comb-shaped flexible printed wiring board using a Baker type applicator so that the dry thickness on the copper foil was 20 μm, and then 80 Dry in an oven at 20 ° C. for 20 minutes.

The dried coating was then heat cured in a 150 ° C. oven for 30 minutes. Thereafter, the entire surface of the insulating film is exposed by irradiating an ultraviolet ray with an accumulated exposure amount of 300 mJ / cm ² , developed with a 1 wt% sodium carbonate aqueous solution at 30 ° C. for 90 seconds, and then in an oven at 150 ° C. for 30 seconds. Heat cured over a period of minutes.

  Evaluation of Comparative Examples 1 and 2 was carried out in the same manner as in the Examples, and the results are shown in Table 2.

A 1st location B 2nd location 1 Photosensitive thermosetting resin composition 2 Flexible printed wiring board 3 Negative mask 4 Actinic ray 5 Exposed portion in the first location 6 Polyimide tape 7 Second location before thermosetting 8 Hot air 9 Exposure-cured and heat-cured portion 10 Heat-cured portion without exposure-curing 11 Copper wiring 12 Polyimide film 13 First location on comb pattern 14 Second location on comb-shaped pattern

Claims (7)

The insulating film on the same flexible printed circuit board has a first location that is exposed and cured by heat, and a second location that is thermally cured without being exposed and cured, and the first location and the second location. A flexible printed wiring board characterized in that the portions are obtained from the same photosensitive thermosetting resin composition.   The photosensitive thermosetting resin composition contains at least (A) a base polymer, (B) a radical polymerizable compound, (C) a photopolymerization initiator, and (D) a thermosetting resin. 1. The flexible printed wiring board according to 1.   The flexible printed wiring board according to claim 1, wherein the first portion is patterned. After the photosensitive thermosetting resin composition is applied and dried on the flexible printed wiring board, the first portion is exposed and cured, and then the first portion and the second portion are thermally cured to form an insulating film. It forms, The manufacturing method of the flexible printed wiring board of any one of Claims 1-3 characterized by the above-mentioned. The first film is exposed and cured, and then the first film is alkali-developed, and then the first film and the second film are thermally cured to form an insulating film. Item 5. A method for producing a flexible printed wiring board according to Item 4. After the photosensitive thermosetting resin composition is applied and dried on the flexible printed wiring board, the second portion is thermally cured, and then the first portion is exposed and cured, and the first portion and the second portion are further cured. method of manufacturing a flexible printed wiring board according to any one of claims 1 to 3, the locations and forming an insulating film by thermal curing. After the first portion is exposed and cured, the first portion is alkali-developed, and further, the first portion and the second portion are thermally cured to form an insulating film. The manufacturing method of the flexible printed wiring board of Claim 6.