JP6039398B2 - Manufacturing method of flexible printed wiring board - Google Patents

Description

  The present invention relates to a method for manufacturing a flexible printed wiring board having excellent adhesion between an insulating film and a copper foil after a gold plating process.

  Generally, a film-like printed wiring board (hereinafter abbreviated as a flexible printed wiring board) mounted on a small device such as a mobile phone or a digital camera is (1) a circuit forming process of a copper-clad laminate, 2) Circuit board protection process by coverlay and cover coat, (3) Surface treatment process for performing gold plating on exposed copper foil and parts mounting part, (4) Laminating plate, (5) Punching, etc. It is manufactured through the outer shape processing step.

  (2) Circuit board protection process for flexible printed circuit boards: A photosensitive resin composition that excels in insulation, heat resistance, solvent resistance, flame retardancy, etc., is applied to the circuit board in liquid form or pasted in film form. And after forming the film | membrane of the photosensitive resin composition, a fine pattern (insulating film) is easily formed by performing exposure, image development, and heating with a photographic technique, and a circuit board is protected.

  Furthermore, various (3) surface treatment processes are selected for copper foil exposed parts and component mounting parts depending on the application, and gold is plated on flexible printed wiring boards with switch contacts and anisotropic conductive film (ACF) connection terminals. A flexible printed wiring board that is subjected to a high-density mounting is subjected to a gold plating process or a rust prevention (OSP) process.

  In particular, troubles in the use of flexible printed wiring boards include (3) many problems related to the gold plating process in the surface treatment process, and the infiltration of a gold plating chemical into the insulating film / copper interface has been reported. One of the causes is that the oxidation state of the copper foil surface is important. The heat curing of the photosensitive resin composition oxidizes the copper surface at the insulating film / copper interface, causing erosion of the gold plating chemical solution and, in the worst case, until peeling. In order to suppress this, the adhesion of solder resist is improved by roughening the copper surface with a method related to rust prevention treatment of the copper surface, a method of adding an adhesion-imparting agent to the photosensitive resin composition, or a micro-etching agent. The method of making it etc. have been reported (for example, refer patent documents 1-4).

JP 2000-165037 A JP 2004-109555 A Japanese Patent Laid-Open No. 11-160880 Japanese Patent Laid-Open No. 11-29883

  However, in Patent Document 1, the antirust treatment suppresses the infiltration of the gold plating chemical (particularly, the acidic chemical used in the gold plating pretreatment process) into the insulating film / copper interface caused by oxidation of the copper foil. However, infiltration of all chemicals used in the gold plating process (such as chemicals having a reducing action and chemicals having a complexing action) could not be suppressed.

  In Patent Documents 2 and 3, an imidazole compound, a triazole compound, and a mercapto group-containing compound are added to the photosensitive resin composition so that the adhesion-imparting agent directly bonds the insulating film and copper. Although the adhesiveness is improved, there is a case in which the gold plating due to the residue of the photosensitive resin composition on the copper or the gold plating bath derived from the additive is contaminated.

  Further, in Patent Document 4, by roughening the copper surface, the adhesion with the insulating film / copper in a dry state is greatly improved. However, after the gold plating process, the chemical solution penetrates into the insulating film / copper interface. The adhesion could not be maintained because the insulating film became brittle. In particular, in an insulating film obtained from a highly concealable photosensitive resin composition, actinic rays due to exposure are absorbed by the insulating film itself and do not reach the bottom of the insulating film completely, making it difficult to be photocured. As a result, the chemical resistance of the obtained insulating film is reduced, and when performing an extreme chemical treatment like the gold plating treatment step, the gold plating chemical tends to permeate the insulating film / copper interface. The improvement in adhesion after the gold plating process was insufficient.

The inventors of the present application provide a method for manufacturing a flexible printed wiring board in which at least an insulating film is laminated on a copper foil, the manufacturing method including a gold plating treatment step and a heat treatment step after the gold plating treatment step, The breaking strength (E _I ) before performing the gold plating treatment step and the breaking strength (E _II ) after performing the heat treatment step after the gold plating treatment step are (E _II ) / (E _I )> 0.70 It has been found that a flexible printed wiring board having excellent adhesion after the gold plating process can be obtained by adopting a method for producing a flexible printed wiring board characterized by satisfying the above relationship.

That is, a method for manufacturing a flexible printed wiring board in which an insulating film is laminated on a copper foil, wherein the manufacturing method includes a gold plating step and a heat treatment step after the gold plating step, and the gold plating step for the insulating film is performed. The previous breaking strength (E _I ) and the breaking strength (E _II ) after the heat treatment step after the gold plating treatment step satisfy the relationship of (E _II ) / (E _I )> 0.70 It is the manufacturing method of the flexible printed wiring board characterized.

Further, the breaking strength (E _I ) before performing the gold plating treatment of the insulating film and the breaking strength (E _III ) before carrying out the heat treatment step after the gold plating treatment step are (E _III ) / (E _I )> It is preferable to satisfy the relationship of 0.50.

  The insulating film is preferably obtained from a photosensitive resin composition containing at least (A) a binder polymer, (B) a radical polymerizable compound, (C) a photopolymerization initiator, and (D) a thermosetting resin. .

The manufacturing method of the flexible printed wiring board of the present invention is a manufacturing method of a flexible printed wiring board in which at least an insulating film is laminated on a copper foil as described above, and the manufacturing method includes a gold plating process and a gold plating process. after including a heat treatment step, the breaking strength before performing gold plating process of the insulating film and (E _I), the breaking strength after the heat treatment step after the gold plating step and (E _II) but, (E _II ) / (E _I )> 0.70 is satisfied, and a method for manufacturing a flexible printed wiring board having excellent adhesion after a gold plating process is provided. It is something that can be done.

It is the schematic diagram which has measured the curvature amount of the film. It is a schematic diagram (tape laminating method) of a tape peeling test. It is a schematic diagram (tape peeling method) of a tape peeling test.

  The present inventors have found that the flexible printed wiring board of the present invention is excellent in various characteristics, but this is presumed to be due to the following reasons.

The decrease in adhesion at the interface between the insulating film and the copper foil after the gold plating process is due to the fact that a chemical layer in the gold plating process penetrates into the insulating film, so that a fragile layer that easily takes moisture into the adhesion interface between the insulating film and the copper foil. Since it is formed (the original strength of the insulating film is reduced), it is considered that when an external stress such as a tape peel is applied, the insulating film near the interface causes cohesive failure. Therefore, the manufacturing method of the flexible printed wiring board according to the present invention includes a heat treatment process after the gold plating process, and therefore reduces the moisture present at the interface between the insulating film and the copper foil after the gold plating process, thereby reducing the strength of the insulating film. It is believed that it is possible to provide a flexible printed wiring board that can suppress the generation of a suppressed fragile layer and has excellent adhesion after the gold plating process. Furthermore, the breaking strength (E _I ) before performing the gold plating treatment step of the insulating film and the breaking strength (E _II ) after performing the heat treatment step after the gold plating treatment step are (E _II ) / (E _I ) By selecting an insulating film satisfying a relationship of> 0.70, it is possible to provide a flexible printed wiring board having excellent adhesion after the gold plating process.

  Hereinafter, the photosensitive resin composition, the method for forming an insulating film, the gold plating process, the heat treatment process, and the method for measuring the breaking strength will be described for the present invention.

[Photosensitive resin composition]
The photosensitive resin composition of the present invention is not particularly limited as long as it is a photosensitive resin composition, but at least (A) a binder polymer, (B) a radical polymerizable compound, (C) a photopolymerization initiator, (D) It is preferable to contain a thermosetting resin. Moreover, the photosensitive resin composition in this invention will not be limited if it is a material which can fulfill | perform the function calculated | required as a hardened | 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.

  Hereinafter, (A) binder polymer, (B) radical polymerizable compound, (C) photopolymerization initiator, (D) thermosetting resin, and other components will be described.

[(A) Binder polymer]
The (A) binder 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) binder 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 (B) 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.

  In the photosensitive resin composition, the (B) radical 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 excluding the component (B). It is preferable at the point which photosensitivity improves.

  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 the (C) photopolymerization initiator include Mihilaz 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, benzoin isobutyl ether, 2-t-butylanthraquinone, 1,2-benzo-9,10-anthraquinone, methylanthraquinone, thioxanthone, 2,4-diethylthioxanthone, 2-isopropylthioxanthone, 1- Hydroxycyclohexyl phenyl ketone, diacetylbenzyl, benzyldimethyl Ketal, 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)- Enyl] -2-hydroxy-2-methyl-1-propan-1-one, 2-methyl-1- [4- (methylthio) phenyl] -2-morpholinopropan-1-one, 2-benzyl-2- Dimethylamino-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- Kutandione, 1- [4- (phenylthio)-, 2- (O-benzoyloxime)], iodium, (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 (C) photopolymerization initiator in the present invention is preferably blended in an amount of 0.1 to 50 parts by weight with respect to a total of 100 parts by weight of the components excluding the component (C).

  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, and unsaturated polyester resin; allyl on the side chain or terminal of the polymer chain 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 Etototo YH- 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 50 parts by weight, particularly 100 parts by weight of the total component excluding the component (D). Preferably, it is 5 to 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) binder polymer, (B) radical polymerizable compound, (C) photopolymerization initiator, and (D) thermosetting resin, the photosensitive resin composition in the present invention includes a filler flame retardant as necessary. Further, additives such as a colorant, an adhesion imparting agent, a polymerization inhibitor and an organic solvent may be contained.

  Although it will not specifically limit if the filler in this invention is what is called an organic filler or an inorganic filler, As a shape, spherical shape, powder shape, fibrous shape, needle shape, scale shape, etc. are mentioned. Examples of the organic filler include polytetrafluoroethylene powder, polyethylene, benzoguanamine, melamine, phthalocyanine powder and the like, as well as a multi-layer core shell using silicone, acrylic, styrene butadiene rubber, butadiene rubber, and the like. Examples of the inorganic filler include silica, metal oxides such as titanium oxide and alumina, metal nitrogen compounds such as silicon nitride and boron nitride, metal salts such as calcium carbonate, calcium hydrogen phosphate, calcium phosphate, and aluminum phosphate. These can be used alone or in combination of two or more. Particularly when it is a metal oxide, a metal nitrogen compound, or a metal salt, it has a high affinity with oxygen atoms, hydroxyl groups, adsorbed water, etc., which are defects on the copper surface, and can improve the adhesion with the insulating film / copper. Therefore, it is preferable.

  Further, the surface of the filler may be coated with a silane coupling agent, other organic compounds, etc., and surface modification such as hydrophilicity or hydrophobicity may be performed. These can be used alone or in combination of two or more.

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 using three rolls after completion of polymerization. Any method such as a method of preparing a dispersion containing a filler and mixing it with the photosensitive 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 a photosensitive resin composition 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. It is preferable that 1-100 weight part is mix | blended with respect to a total of 100 weight part of components other than a flame retardant in the photosensitive resin composition of this invention. The blending ratio is preferable because flame retardancy is improved without impairing the developability and photosensitivity of the photosensitive resin composition and the bending resistance of the resulting cured film. When there are few flame retardant components than the said range, the flame retardance of the cured film of the photosensitive resin composition may become inadequate. Moreover, when there are more flame retardant components than the said range, the developability and photosensitivity of the photosensitive resin composition may fall.

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

  As a solvent in this invention, what is necessary is just a solvent which can dissolve the photosensitive resin composition component. 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 40 parts by weight based on 100 parts by weight of the total components other than the solvent in the photosensitive resin composition. ~ 100 parts by weight. It is preferable to adjust the amount of the solvent within the above range since the viscosity and viscosity of the photosensitive 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 photosensitive 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 the photosensitive resin composition will become very low, application | coating will become difficult and the circuit coverage may be inferior.

[Circuit board]
The circuit board used for the flexible printed wiring board in this invention can be manufactured using the copper-laminated laminated board which bonded together base films, such as a polyimide, and copper foil, for example. For the bonding of the base film and copper foil, you can choose between those that use an adhesive and those that do not use an adhesive. For those that do not use an adhesive, choose the cast method, laminate method, or metallization method. Can do. Thereafter, a circuit can be formed by a subtracting method (for example, a method of forming a circuit in the order of a via hole processing step, a desmear treatment step, a via plating step, an etching resist formation step, an etching step, and a resist removal step) as necessary. . Another method of manufacturing the circuit board of the present invention is a semi-additive method (a base layer such as polyimide is provided with a seed layer such as nickel chrome, a copper sputter layer is provided, and then electrolytic copper plating is performed. It is also possible to select a method of forming a circuit in the order of the forming step, the exposing step, the developing step, the copper plating step, and the plating resist removing step. Thereafter, the copper foil on the circuit board can be used after roughening.

  Moreover, as a roughening method of copper foil, physical grinding | polishing, such as buff grinding | polishing, scrub grinding | polishing, or grinder grinding | polishing, chemical grinding | polishing using a microetching agent, etc. are mentioned. In particular, microetching is preferable for processing a substrate having a fine pattern. As the micro-etching agent, an etching agent mainly composed of sulfuric acid / hydrogen peroxide, an etching agent mainly composed of iron (III) chloride or iron (III) sulfate, or an organic acid based etching agent is used. Can do. Examples of such a micro-etching agent include Mec Etch Bond STZ-3100, STL-3300, CZ-8100, CZ-8101, Mec V Bond BO-7780V, BO-7790V, Mec Bright CB-5004, CB manufactured by Mec Corporation. -5530, SF-5420, CA-91Y, CB-801Y, CB-5602AY, and the like.

  Furthermore, the copper foil of the circuit board may have a rust prevention layer and / or an organic or inorganic primer layer. Moreover, what has the effect of a rust prevention layer and a primer layer simultaneously is also contained. Examples of such a rust inhibitor and primer treatment agent include MEC Etch Bond CL-8300, CL-8301, and MEC BRIGHT CAU-5232C manufactured by MEC Co., Ltd. Examples of the rust prevention treatment and primer treatment include a method of immersing the circuit board in a chemical solution and a method of spraying with a spray.

[Method of forming insulating film]
Moreover, the photosensitive resin composition in this invention can form an insulating film as follows. First, the photosensitive resin composition is applied onto the circuit board and dried to remove the solvent. The substrate can be applied by screen printing, roller coating, curtain coating, spray coating, spin coating using a spinner, or the like. The coating film (preferably having a thickness of 5 μm to 100 μm) is dried at 120 ° C. or lower, preferably 40 to 100 ° C. After drying, a negative photomask is placed on the dried coating film and irradiated with actinic rays such as ultraviolet rays, visible rays, and electron beams. Next, the pattern can be obtained by washing the unexposed portion with a developing solution using various methods such as shower, paddle, dipping or ultrasonic waves. Since the time until the pattern is exposed varies depending on the spray pressure and flow velocity of the developing device and the temperature of the developer, it is preferable to find the optimum device conditions as appropriate. As the developer, an aqueous alkali solution is preferably used. The developer is water-soluble such as methanol, ethanol, n-propanol, isopropanol, N-methyl-2-pyrrolidone and the like. An organic solvent may be contained. 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, trii Propylamine and the like, aqueous solution compound other than this as long as it exhibits basicity can also be used.

  Moreover, the density | concentration of the alkaline compound which can be used suitably for the image development process of the photosensitive resin composition in this invention becomes like this. Preferably it is 0.01 to 10 weight%, Most preferably, it is 0.05 to 5 weight%. It is preferable. The temperature of the developer depends on the composition of the photosensitive resin composition (A) and the developer, and is generally 0 ° C. or higher and 80 ° C. or lower, more generally 20 ° C. or higher and 50 ° C. or lower. It is preferable to use at a temperature of 0 ° C.

  The pattern formed by the development step is rinsed to remove unnecessary developer residue. Examples of the rinsing liquid include water and acidic aqueous solutions.

  Next, a cured film rich in heat resistance and flexibility can be obtained by performing heat curing treatment. Although a cured film is determined in consideration of wiring thickness etc., it is preferable that thickness is about 2-50 micrometers. The final curing temperature at this time is desired to be cured by heating at a low temperature for the purpose of preventing oxidation of the wiring and the like and not reducing the adhesion between the wiring and the substrate. The heat curing temperature at this time is preferably 100 ° C. or higher and 250 ° C. or lower, more preferably 120 ° C. or higher and 200 ° C. or lower, and particularly preferably 130 ° C. or higher and 190 ° C. or lower. When the final heating temperature becomes high, the wiring may be oxidized and deteriorated.

  In this way, the flexible printed wiring board on which the insulating films are laminated is subjected to gold plating in order to mount the switch contacts, anisotropic conductive film (ACF) connection terminals, and components.

[Gold plating process]
The gold plating process in the present invention comprises at least (I) a degreasing process, (II) an etching process, (III) a catalytic process, (IV) an electroless nickel plating process, and (V) a gold plating process. There is no particular limitation as long as it is a processing step called electrolytic gold plating or electroless gold plating.

  In addition, as the gold plating chemical used in the gold plating process (V) in the present invention, at least a gold salt such as potassium gold cyanide, potassium gold cyanide, or sodium gold sulfite, an organic acid salt, a sulfate, boric acid, Buffers such as phosphate or sulfamic acid, ethylenediaminetetraacetic acid (EDTA), N ′-(2-hydroxyethyl) ethylenediamine-N, N, N′-triacetic acid (HEDTA), nitrilotriacetic acid (NTA), Metal concealing agents such as diethylenetriaminepentaacetic acid (DTPA), triethylenetetraminehexaacetic acid (TTHA), or hydroxyethylidenephosphone (HEDP), cobalt, nickel, silver, iron, palladium, copper, thallium, lead, arsenic, etc. Consists of a crystal modifier. Examples of such gold-plated chemicals include trade names Flash Gold 2000, Flash Gold VT, Flash Gold 330, Flash Gold NC, Denno Noble AU, Self Gold OTK-IT, and Uemura Kogyo Co., Ltd. Product names of Cobrite TMX-22, Cobrite TMX-23, Cobrite TMX-40, Cobrite TSB-71, Cobrite TSB-72, Cobrite TCU-37, Cobrite TUC-38, Cobrite TAM-LC, Cobrite TCL-61, Cobrite TIG-10, Cobrite TAW-66, orical TKK-51, etc. can be mentioned.

[Heat treatment process]
The heat treatment step after the gold plating treatment step in the present invention is performed for the purpose of removing moisture in the insulating film after the gold plating treatment step, the breaking strength (E _I ) before performing the gold plating treatment step of the insulating film, and the gold plating. There is no particular limitation as long as the breaking strength (E _II ) after the heat treatment step after the treatment step satisfies the relationship of (E _II ) / (E _I )> 0.70. A preferable heating temperature range is 50 to 200 ° C., more preferably 80 to 170 ° C., a preferable heat treatment time is 10 seconds or more, more preferably 15 minutes or more, and the heating temperature and the treatment time are within a range in which the characteristics of the insulating film can be maintained. Can be appropriately selected.

  Then, a flexible printed wiring board is manufactured by passing through the process of sticking a reinforcement plate and external processing processes, such as punching.

[Measurement method of breaking strength]
The breaking strength in the present invention indicates the value of stress when the material breaks due to external force, and can be obtained as the stress applied to the cross-sectional unit area. The breaking strength can be measured, for example, using a tensile tester (Autograph S-100-C) manufactured by Shimadzu Corporation according to ASTM-D882.

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

(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 resin solution of 50% by weight of (A) binder polymer having a weight average molecular weight of 10,000.

(Formulation examples 1-5)
A photosensitive resin composition was prepared by adding (A) a binder polymer, (B) a radical polymerizable compound, (C) a photopolymerization initiator, (D) a thermosetting resin, and other components. Table 1 shows the blending amount of each constituent raw material in the resin solid content and the kind of the raw material. After mixing the mixed solution with three rolls, bubbles in the solution were completely defoamed with a defoaming apparatus, and the following evaluation was performed.

<1> Nippon Kayaku Co., Ltd. Binder polymer (urethane-modified epoxy (meth) acrylate, solid content acid value 97.7 mgKOH / g) product name <2> Nippon Kayaku Co., Ltd. binder polymer (bisphenol F type epoxy acrylate) Product name of solid content acid value 100 mgKOH / g) <3> product name of radically polymerizable compound (EO-modified bisphenol A dimethacrylate) manufactured by Hitachi Chemical Co., Ltd. <4> product of radically polymerizable compound manufactured by Nippon Kayaku Co., Ltd. ( Product name <5> Product name of photopolymerization initiator manufactured by BASF Japan <6> Product name of bisphenol A type epoxy resin (epoxy equivalent 188 g / eq) manufactured by Japan Epoxy Resin Co., Ltd. <7> Japan Epoxy Resin Co., Ltd. p-aminophen Product name <8> product name of enol type epoxy resin (epoxy equivalent 96g / eq) <8> Product name of filler (melamine resin / silica composite particles, average particle size 6.5 μm) <9> Clariant Japan Co., Ltd. Product name of filler (aluminum diethylphosphinate, average particle diameter 2.5 μm) <10> Product name of epoxy curing agent (dicyandiamide) manufactured by Japan Epoxy Resin Co., Ltd. Product name of anhydrous silica manufactured by Nippon Aerosil Co., Ltd.

  Moreover, evaluation of the photosensitivity etc. of the photosensitive resin composition was separately performed by the following method. The evaluation results are shown in Table 2.

<Preparation of cured film on polyimide film>
The above photosensitive resin composition was cast and applied to an area of 100 mm × 100 mm on a 75 μm polyimide film (manufactured by Kaneka Corporation: trade name 75 NPI) using a Baker type applicator so that the final dry thickness was 25 μm. After drying at 80 ° C. for 20 minutes, a negative photomask with a line width / space width of 50 mm × 50 mm = 100 μm / 100 μm was placed and irradiated with ultraviolet rays with an integrated exposure amount of 300 mJ / cm ² to be exposed. Subsequently, spray development was performed for 60 seconds at a discharge pressure of 1.0 kgf / mm ² using a solution obtained by heating a 1.0 wt% sodium carbonate aqueous solution to 30 ° C. After development, the film was sufficiently washed with pure water, and then cured by heating in an oven at 160 ° C. for 90 minutes to prepare a cured film of the photosensitive resin composition.

(I) Photosensitivity The photosensitivity of the photosensitive resin composition was determined by observing the surface of the cured film obtained in the above item <Preparation of cured film on polyimide film>.
◯: A clear photosensitive pattern with a line width / space width = 100/100 μm is drawn on the polyimide film surface, the line does not shake due to the peeling of the line portion, and there is no residual residue in the space portion. thing.
(Triangle | delta): The thing with which the clear line width / space width = 100/100 micrometer photosensitive pattern was not drawn on the polyimide film surface (those with the line width of line width).
X: A photosensitive pattern of line width / space width = 100/100 μm is not drawn on the surface of the polyimide film, and a dissolution residue is generated.

(Ii) Solvent resistance The solvent resistance of the cured film obtained in the above item <Preparation of cured film on polyimide film> was evaluated. In the evaluation method, the film was dipped 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.

(Iii) Folding resistance The cured film of the photosensitive resin composition is laminated on the surface of a polyimide film having a thickness of 25 μm (Apical 25NPI manufactured by Kaneka Corporation) in the same manner as in the above item <Preparation of coating film on polyimide film>. A film was prepared. The cured film laminated film was cut into a 30 mm × 10 mm strip, bent 10 times at 180 ° at 15 mm, and the coating film was visually confirmed to check for cracks.
○: The cured film has no cracks.
Δ: The cured film has some cracks.
X: The cured film has cracks.

(Iv) Warpage A cured film laminated film of a photosensitive resin composition was applied to the surface of a 25 μm-thick polyimide film (Apical 25NPI manufactured by Kaneka Corporation) in the same manner as in the above item <Preparation of coating film on polyimide film>. Produced. The produced cured film laminated film is processed into a 5 cm square, and the warp heights at the four corners are measured. A schematic diagram of measuring the amount of warpage of the film is shown in FIG.
○: The average warp height is less than 10 mm.
Δ: The average warp height is 10 mm or more and less than 20 mm.
X: The average of the warp height is 20 mm or more.

(V) Insulation reliability Line width / space width = 100 μm on a flexible copper-clad laminate (copper foil thickness 12 μm, polyimide film is Apical 25 NPI manufactured by Kaneka Corporation, and copper foil is bonded with polyimide adhesive) A / 100 μm comb-shaped pattern was prepared, immersed in a 10% by volume sulfuric acid aqueous solution for 1 minute, washed with pure water, and subjected to a copper foil surface treatment. Thereafter, a cured film of the photosensitive resin composition was prepared on the comb pattern by the same method as the above <Preparation of cured film on polyimide film>, and the test piece was adjusted. A 100 V direct current was applied to both terminals of the test piece in an environmental test machine at 85 ° C. and 85% RH, and changes in the insulation resistance value and occurrence of migration were 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.

(Vi) Press resistance A cured film laminated film of a photosensitive resin composition was prepared on the surface of a 35-μm-thick copper foil by the same method as in the above item <Preparation of coating film on polyimide film>. However, the exposure was performed by using a 100 μm square opening mask and irradiating with an ultraviolet ray with an integrated exposure amount of 300 mJ / cm ² . Then, the cured film laminated film of the photosensitive resin composition produced above was heated and pressurized at 165 ° C./90 min with a hot press, and the deformation amount of the square opening was measured.
○: Opened by 90 μm or more after hot pressing.
(Triangle | delta): 80-90 micrometers opening after hot press.
X: Opening of 80 μm or less after hot pressing.
Further, level 2 was not opened and the test could not be performed.

(Vii) Solder heat resistance In the same manner as in the above item <Preparation of cured film on polyimide film>, a cured film of a photosensitive resin composition is laminated on the surface of a polyimide film 75 μm thick (Apical 75NPI manufactured by Kaneka Corporation). A film was prepared. However, the exposure was performed by irradiating the entire surface with ultraviolet rays having an accumulated exposure amount of 300 mJ / cm ² without using a negative mask.
The cured film was floated so that the surface coated with the cured film of the photosensitive resin composition was in contact with a solder bath in which the cured film was completely dissolved at 260 ° C., and then pulled up 10 seconds later. The operation was performed three times, and the adhesive strength of the cured film was evaluated by a cross-cut tape method according to JIS K5400.
○: No peeling by cross-cut tape method.
Δ: 95% or more of the cells remain.
X: The remaining amount of the mesh is less than 80%.

<Method for producing copper foil with insulating film>
Using a baker type applicator, the photosensitive resin compositions of Formulation Examples 1 to 5 were made into copper foil (Mitsui Metal Mining Special Electrolytic Copper Foil 3EC-VLP, thickness 35 μm, roughness 0.2 μm) with a final dry thickness of 20 μm. After casting and coating to an area of 100 mm × 100 mm and drying at 80 ° C. for 20 minutes, a negative photomask of 50 mm × 50 mm area line width / space width = 100 μm / 100 μm is placed and 300 mJ / cm Exposure was performed by irradiating with an ultraviolet ray of ² accumulated exposure amount. Subsequently, spray development was performed for 60 seconds at a discharge pressure of 1.0 kgf / mm ² using a solution obtained by heating a 1.0 wt% sodium carbonate aqueous solution to 30 ° C. After development, the substrate was thoroughly washed with pure water and then heat-cured in an oven at 160 ° C. for 90 minutes to produce a copper foil with an insulating film.

<Tape peeling evaluation method after electroless gold plating>
An electroless gold plating process was performed according to the following using the copper foil with an insulating film produced above. The electroless gold plating process was performed as follows according to the standard process of Okuno Pharmaceutical Co., Ltd. electroless gold plating Flash Gold 330.
(I) Degreasing treatment, ICP Clean S-135K, 40 ° C., 4 minutes (II) Etching treatment, sulfuric acid 10 mL / L, sodium persulfate 100 g / L, copper sulfate pentahydrate, 8 g / L, ion exchange Prepared to 1 L with water, 30 ° C., 1 minute (III) catalyzed treatment, ICP accelerator (Pd: 0.04%), 30 ° C., 1 minute (IV) electroless nickel plating treatment, ICP-Nicolon FPF, 84 ℃, 30 minutes (V) gold plating treatment, flash gold 330, 80 ℃, 8 minutes.
After the electroless gold plating treatment, the substrate was washed with water at room temperature, and heat treatment was performed at 80 ° C. for 15 minutes, at 100 ° C. for 10 seconds, and at 150 ° C. for 30 minutes. Moreover, after water washing, what wiped off the water | moisture content of the copper foil with an insulating film was made into the heat processing process without (unprocessed), and the tape peeling test was implemented within 30 minutes after the gold plating process.

(Viii) Tape peel test As shown in FIG. 2, the tape peel test is performed by attaching a Nichiban cellophane tape (18 mm width) to the line / space photosensitive pattern so as to be perpendicular to the line / space direction, and rubbing firmly. Paste so that air does not get into the part. Thereafter, as shown in FIG. 3, a peel test was performed at a peeling direction of about 60 °. The results are shown in Table 3.
○: No tape peeling.
Δ: Some tape peeling occurred and the remaining fine line pattern was 80%.
X: Tape peeling occurred and the thin line pattern remaining was less than 80%.

<Measurement of breaking strength>
The photosensitive resin composition was cast and applied to a 250 mm × 200 mm area on a 12.5 μm copper foil using a Baker applicator so that the final dry thickness was 8 μm, and dried at 80 ° C. for 20 minutes. Then, exposure was performed by irradiating with an ultraviolet ray having an accumulated exposure amount of 300 mJ / cm ² . Subsequently, spray development was performed for 60 seconds at a discharge pressure of 1.0 kgf / mm ² using a solution obtained by heating a 1.0 wt% sodium carbonate aqueous solution to 30 ° C. After development, the film was sufficiently washed with pure water, and then cured by heating in an oven at 160 ° C. for 90 minutes to prepare a cured film of the photosensitive resin composition. The cured film was immersed in an aqueous ferric chloride solution (40%) at 30 ° C. to dissolve only the copper foil, and then sufficiently washed with water to wipe off the moisture on the surface, thereby obtaining a single-layer cured film.

  The obtained single-layer cured film was left to stand at 25 ° C. and 50% RH for 24 hours, and then the tensile strength was measured according to ASTM-D882 using a Shimadzu tensile tester (Autograph S-100-C). . The width of the test piece is 15 mm, the thickness is 8 μm, the distance between chucks is 100 mm, and the total length is 200 mm. The average value of N = 5 of measured values was used as the value of breaking strength.

In addition, after the single layer cured film is processed in the electroless gold plating process, it is heated at 80 ° C. for 15 minutes, at 100 ° C. for 10 seconds and at 150 ° C. for 30 minutes without the heat treatment process. The break strength was measured in the same manner for the treated sample. The breaking strengths of those without heat treatment step (untreated) are (E _III ), and the breaking strengths of those subjected to heat treatment at 80 ° C. for 15 minutes, 100 ° C. for 10 seconds and 150 ° C. for 30 minutes are (E _II 1), (E _II 2) and (E _II 3).
Table 4 shows the relationship (ratio) between the results and the breaking strength.

DESCRIPTION OF SYMBOLS 1 Polyimide film which laminated the photosensitive resin composition 2 Warpage amount 3 Smooth stand 4 Copper foil 5 Insulating film (line part)
6 Cellophane tape

Claims (2)

A method for manufacturing a flexible printed wiring board in which an insulating film is laminated on a copper foil, wherein the manufacturing method includes a gold plating treatment step and a heat treatment step after the gold plating treatment step, and before performing the gold plating treatment step of the insulation film and the breaking strength (E _I), the breaking strength after the heat treatment step after the gold plating step and (E _II) but meets the relationship _{(E II) / (E I} )> 0.70, and,
The breaking strength (E _I ) before the gold plating treatment of the insulating film and the breaking strength (E _III ) before the heat treatment step after the gold plating treatment step are (E _III ) / (E _I )> 0. method of manufacturing a flexible printed wiring board, characterized in Succoth meet the 50 relationships. The insulating film is obtained from a photosensitive resin composition containing at least (A) a binder polymer, (B) a radical polymerizable compound, (C) a photopolymerization initiator, and (D) a thermosetting resin. The manufacturing method of the flexible printed wiring board of Claim 1 to do .