JP4782616B2 - Photosensitive resin composition and printed circuit board obtained using the same - Google Patents

Description

  The present invention relates to a photosensitive resin composition and a printed circuit board obtained using the same and having a solder resist.

  For printed circuit boards on which electronic components such as semiconductor elements are mounted by soldering, a polyimide film on which an adhesive layer called a coverlay is formed is punched into a predetermined shape, and is pasted on a conductor pattern. Alternatively, a cover insulating layer (including a solder resist layer) is provided on the conductor pattern such that a heat resistant material called a solder resist is provided on a necessary portion by a screen printing method or an exposure development method. Yes.

  Such a cover insulating layer is required to have characteristics such as solder heat resistance, insulation, flame retardance when mounting a component by solder, and folding resistance in a flexible printed wiring board.

  At present, the cover lay formed by punching the polyimide film with the adhesive layer formed into a predetermined shape is most often used to satisfy the above-mentioned characteristics. There is a problem that a mold is required, and the punched film is manually aligned and bonded, resulting in high costs and difficulty in forming a fine pattern.

In order to solve such a problem, for example, a liquid photosensitive resist material mainly composed of an epoxy resin such as bisphenol A type epoxy resin, bisphenol F type epoxy resin, or novolak type epoxy resin has been proposed (patent). Reference 1, 2, 3). These enable the formation of a fine pattern. This kind of liquid photosensitive resist material, which is excellent in formability, folding resistance and low stress properties of a fine pattern, is mainly composed of urethane acrylate and has excellent folding resistance of a cured product. (See Patent Document 4).
JP-A-7-207211 JP-A-8-134390 Japanese Patent Laid-Open No. 9-5997 JP-A-7-253666

  However, the liquid photosensitive resist material mainly composed of epoxy resin such as bisphenol A type epoxy resin, bisphenol F type epoxy resin, novolac type epoxy resin or the like has the above various epoxy resins as the main component, so that it has folding resistance. And has a problem of poor low stress. Further, there is a problem that the photosensitive resist material having the above-mentioned urethane acrylate as a main component and excellent in folding resistance is not sufficient in terms of solder heat resistance.

  In addition, the printed circuit board is required to have uniform plating on the opening pad portion for mounting electronic components, but there is a problem that this is still insufficient with the above materials.

  The present invention has been made in view of such circumstances, and is a photosensitive resin composition excellent in folding resistance, low stress property, solder heat resistance, and good plating ride uniformity, and wiring obtained using the same. The purpose is to provide a circuit board.

（Ｅ）テトラゾール化合物。
（Ｆ）下記の一般式（２）で表されるエポキシ樹脂。

In order to achieve the above object, the present invention has a photosensitive resin composition containing the following components (A) to ( F ) as a first gist.
(A) A carboxyl group-containing linear polymer.
(B) An ethylenically unsaturated group-containing polymerizable compound.
(C) Photopolymerization initiator.
(D) A heterocyclic mercaptan compound represented by the following general formula (1).

(E) Tetrazole compound.
(F) An epoxy resin represented by the following general formula (2).

  Then, a wiring circuit formed by forming a photosensitive resin composition layer on the conductor circuit pattern using the photosensitive resin composition, and exposing and developing the photosensitive resin composition layer to develop a predetermined pattern to form a cover insulating layer The substrate is a second gist.

That is, the present inventor conducted a series of studies in order to obtain a photosensitive resin composition excellent in folding resistance, low stress property, and solder heat resistance and having good plating ride uniformity. In the course of this research, together with the above carboxyl group-containing linear polymer [component (A)], ethylenically unsaturated group-containing polymerizable compound [component (B)], and photopolymerization initiator [component (C)] The present inventors have found that it is effective to use the heterocyclic mercaptan compound [component (D)] represented by the general formula (1). As a result of further research, when these components and a tetrazole compound [(E) component] and a specific epoxy resin [(F) component] are used in combination, they are excellent in folding resistance, low stress property, solder heat resistance, In addition, the inventors have found that good plating ride uniformity can be obtained and have reached the present invention.

As described above, the photosensitive resin composition of the present invention includes the carboxyl group-containing linear polymer [component (A)], the ethylenically unsaturated group-containing polymerizable compound [component (B)], and a photopolymerization initiator. Along with [component (C)], the heterocyclic mercaptan compound [component (D)] and tetrazole compound [(E) component] represented by the above general formula (1), and the above general formula (2) Contains epoxy resin [component (F)] .

  For this reason, excellent folding resistance, low stress, solder heat resistance, and plating ride uniformity can be achieved. Then, by using the photosensitive resin composition of the present invention, a printed circuit board having excellent characteristics can be obtained by forming a cover insulating layer on the conductor circuit pattern. Such a printed circuit board, for example, flexible printed wiring Electronic components such as LSIs, diodes, transistors, and capacitors are mounted on a board by soldering or the like to form a mounting substrate, which is effectively used for small devices such as mobile phones.

As described above, in the present invention, when the epoxy resin [component (F)] represented by the general formula (2) is used in addition to the components (A) to (E), a more excellent folding resistance is obtained. It becomes possible to demonstrate.

  Further, when the carboxyl group-containing linear polymer [component (A)] has a weight average molecular weight (Mw) in the range of 5000 to 50000, it is possible to exhibit excellent alkali developability. .

  Further, when the bisphenol A (meth) acrylate compound represented by the general formula (3) is used as the ethylenically unsaturated group-containing polymerizable compound [component (B)], folding resistance, solder heat resistance and alkali It becomes more excellent in developability.

  Here, (meth) acrylic acid in the present invention means acrylic acid and methacrylic acid corresponding thereto, and (meth) acrylate means acrylate and methacrylate corresponding thereto.

The photosensitive resin composition of the present invention comprises a carboxyl group-containing linear polymer (component A), an ethylenically unsaturated group-containing polymerizable compound (component B), a photopolymerization initiator (component C), a heterocyclic ring. It is obtained using a formula mercaptan compound (D component), a tetrazole compound (E component), and a specific epoxy resin (F component) .

  The carboxyl group-containing linear polymer (component A) is not particularly limited. For example, an acid anhydride is opened on the hydroxyl group of a compound obtained by adding (meth) acrylic acid to an epoxy resin. Those added, those obtained by ring-opening addition of acid anhydrides to hydroxyl groups such as polyols and phenoxy resins, linear polymers of ethylenically unsaturated compounds containing (meth) acrylic acid, and polyamic acids are used. In particular, the acid equivalent of the linear polymer can be arbitrarily controlled, and the physical property design such as glass transition temperature (Tg) is easy due to the abundance of raw material monomer types. It is preferable to use a linear polymer of an ethylenically unsaturated compound containing an acid.

  The weight average molecular weight of the carboxyl group-containing linear polymer (component A) is preferably in the range of 5000 to 50000, more preferably 6000 to 40000, and still more preferably in the range of 7000 to 30000. That is, when the weight average molecular weight is less than 5,000, the solder heat resistance tends to deteriorate, and when it exceeds 50,000, the alkali developability tends to deteriorate.

  Moreover, it is preferable that the acid equivalent of the said carboxyl group containing linear polymer (A component) is the range of 200-900, More preferably, it is 250-850, More preferably, it is the range of 300-800. That is, if the acid equivalent is less than 200, a tendency to promote oxidation of copper under high temperature and high humidity is observed, and if it exceeds 900, alkali developability tends to be deteriorated.

  Furthermore, when using the linear polymer of the ethylenically unsaturated compound containing the (meth) acrylic acid as the carboxyl group-containing linear polymer (component A), from the viewpoint of improving folding resistance, phenoxy is used. What uses ethyl (meth) acrylate as a copolymerization component is preferable.

  Specific examples of the carboxyl group-containing linear polymer (component A) comprising such a copolymer include, for example, copolymerization with phenoxyethyl (meth) acrylate, (meth) acrylic acid and other vinyl monomers. And the copolymer obtained.

  Examples of the other vinyl monomers include (meth) acrylic acid methyl ester, (meth) acrylic acid ethyl ester, (meth) acrylic acid alkyl ester such as (meth) acrylic acid alkyl ester, (meth) acrylic acid 2 -Ethylhexyl ester, (meth) acrylic acid tetrahydrofurfuryl ester, (meth) acrylic acid dimethylaminoethyl ester, (meth) acrylic acid diethylaminoethyl ester, styrene, α-styrene, vinyltoluene, N-vinylpyrrolidone, (meth) Examples thereof include 2-hydroxyethyl acrylate, acrylamide, acrylonitrile, methacrylonitrile, N-phenylmaleimide, cyclohexylmaleimide and the like. These may be used alone or in combination of two or more.

  The copolymerization amount of phenoxyethyl (meth) acrylate as the copolymer component is set to 10 to 92 parts by weight (hereinafter abbreviated as “parts”) in the total amount of the copolymer (100 parts by weight, the same shall apply hereinafter). Is more preferable, and the range of 20 to 90 parts is more preferable. That is, when the copolymerization amount is less than 10 parts, folding resistance tends to decrease. When it exceeds 92 parts, folding resistance is obtained, but the alkali developability of the generated solder resist tends to decrease. Because it is.

  Moreover, it is preferable to set the copolymerization amount of the (meth) acrylic acid which is the said copolymerization component to 8-40 parts in the total amount of a copolymer, More preferably, it is the range of 10-35 parts. That is, if the copolymerization amount is less than 8 parts, the development time tends to be long and the workability tends to be reduced, and if it exceeds 40 parts, the copper oxidation tends to be promoted under high temperature and high humidity. is there.

  And the copolymerization amount of the other vinyl monomer which is the said copolymerization component is preferably 0 to 72 parts, more preferably 0 to 60 parts in the total amount of the copolymer. That is, if the copolymerization amount exceeds 72 parts, the flame retardancy and developability tend to be reduced.

  The ethylenically unsaturated group-containing polymerizable compound (B component) used together with the A component is not particularly limited, but is a bisphenol A (meth) acrylate compound represented by the following general formula (3). Is preferable from the viewpoint of excellent balance of properties such as solder heat resistance, folding resistance and alkali developability.

  In the above formula (3), examples of the alkylene group having 2 to 6 carbon atoms include an ethylene group, a propylene group, an isopropylene group, a butylene group, an isobutylene group, a pentylene group, a neopentylene group, and a hexylene group. In particular, an ethylene group is preferable.

  The isopropylene group is a group represented by —CH (CH 3) CH 2 —, and in — (O—Y 1) — and — (Y 2 —O) — in the above general formula (3), the bonding direction is methylene. There are two types, when the group is bonded to oxygen and when the methylene group is not bonded to oxygen, one bonding direction may be used, or two bonding directions may be mixed.

  When the number of the repeating units-(O-Y1)-and-(Y2-O)-is 2 or more, two or more Y1 and two or more Y2 may be the same or different from each other. And when Y1 and Y2 are comprised by 2 or more types of alkylene groups, 2 or more types of-(O-Y1)-and-(Y2-O)-may exist at random or may be block-like. May be present.

  In the general formula (3), the substitutable positions of the two benzene rings may have one or more substituents or atoms, and have two or more substituents or atoms. In some cases, these substituents or atoms may be the same or different. Examples of the substituent or atom include an alkyl group having 1 to 20 carbon atoms, a cycloalkyl group having 3 to 10 carbon atoms, an aryl group having 6 to 14 carbon atoms, an amino group, a nitro group, a cyano group, and a mercapto. Group, allyl group, alkyl mercapto group having 1 to 10 carbon atoms, hydroxyalkyl group having 1 to 20 carbon atoms, carboxyalkyl group having 1 to 10 carbon atoms in alkyl group, acyl having 1 to 10 carbon atoms in alkyl group Group, a C1-C20 alkoxy group or a group containing a heterocyclic ring, a halogen atom, and the like.

  In the general formula (3), the number of repetitions p and q is a positive integer selected such that p + q is 4 to 40, more preferably a positive integer selected so that p + q is 4 to 15. Particularly preferably, it is a positive integer selected such that p + q is 5 to 13. That is, when p + q is less than 4, folding resistance tends to decrease. When p + q exceeds 40, the entire photosensitive resin composition exhibits hydrophilicity, and insulation reliability under high temperature and high humidity is improved. This is because an inferior tendency is seen. P or q may be 0, but usually a value of 1 is selected as the minimum value.

  Specific examples of the bisphenol A-based (meth) acrylate compound represented by the general formula (3) include 2,2′-bis [4- (meth) acryloxydiethoxyphenyl] propane, 2,2 ′. -Bis [4- (meth) acryloxytetraethoxyphenyl] propane, 2,2'-bis [4- (meth) acryloxypentaethoxyphenyl] propane, 2,2'-bis [4- (meth) acryloxy And diethoxyoctapropoxyphenyl] propane, 2,2′-bis [4- (meth) acryloxytriethoxyoctapropoxyphenyl] propane, and the like. These may be used alone or in combination of two or more.

  Examples of the photopolymerization initiator (component C) used together with the components A and B include substituted or unsubstituted polynuclear quinones (2-ethylanthraquinone, 2-t-butylanthraquinone, octamethylanthraquinone, 1,2- Benzanthraquinone, 2,3-diphenylanthraquinone, etc.), α-ketaldonyl alcohols (benzoin, pivalon, etc.), ethers, α-hydrocarbon-substituted aromatic acyloins (α-phenyl-benzoin, α, α'- Diethoxyacetophenones, etc.), aromatic ketones (benzophenone, 4,4′-bisdialkylaminobenzophenones such as N, N′-tetraethyl-4,4′-diaminobenzophenone, etc.), thioxanthones (2-methylthioxanthone, 2,4-diethylthioxanthone, 2-chlorothioxanthone , 2-isopropylthioxanthone, 2-ethylthioxanthone, etc.), 2-methyl-1- [4- (methylthio) phenyl] -morpholinopropan-1-one, and the like. These may be used alone or in combination of two or more.

  The D component used together with the A to C components is a heterocyclic mercaptan compound represented by the following general formula (1).

  In the above formula (1), the 5-membered ring formed by combining X which is a divalent group and —N═C—S— specifically includes a thiazole ring, a thiazoline ring, a thiadiazole ring, A thiatriazole ring and the like.

  When X is an aromatic ring and is an atomic group that forms a condensed ring with the 5-membered ring, specific examples of the condensed ring include the following benzothiazole ring, benzothiazoline ring, and benzothiadiazole ring. Can be mentioned.

  These 5-membered or aromatic rings are a halogen atom (for example, chlorine, bromine, etc.), an alkyl group (preferably a lower alkyl group having 1 to 4 carbon atoms, for example, a methyl group, an ethyl group, an n-propyl group). , N-butyl group, etc.), alkoxy groups (preferably alkoxy groups having 1 to 4 carbon atoms such as methoxy group, ethoxy group, n-propoxy group, n-butoxy group, etc.), amino groups, alkylamino groups ( For example, an atom or substituent selected from the group consisting of a methylamino group, an ethylamino group, an n-propylamino group, etc.), an alkoxycarbonyl group (eg, a methoxycarbonyl group, an ethoxycarbonyl group, etc.), a mercapto group, and a phenyl group. And may be the same or different from each other.

  Specific examples of the heterocyclic mercaptan compound (component D) represented by the general formula (1) include, for example, 2-amino-5-mercapto-1,3,4-thiadiazole, 5-chloro-2-mercaptobenzo Thiazole, 6-ethoxy-2-mercaptobenzothiazole, 2-mercaptobenzothiazole, 5,5′-dimethyl-2-mercaptothiazoline, 2-mercaptothiazoline, 4-methoxycarbonyl-5,5′-dimethyl-2-mercapto Thiazoline, 5-amino-2-mercaptothiazole, 2-mercapto-4,5-dimethylthiazole, 2-mercapto-4-methylthiazole, 2-mercapto-4-phenylthiazole, 2-mercaptothiazole, 5-amino-2 -Mercapto-1,3,4-thiadiazole, 3,5-dimerca To-1,2,4-thiadiazole, 2,5-dimercapto-1,3,4-thiadiazole, 5-methylamino-2-mercapto-1,3,4-thiadiazole, 2-mercapto-5-phenyl-1 3,4-thiadiazole, 5-methyl-2-mercapto-1,3,4-thiadiazole, 3-phenyl-5-mercapto-1,2,4-thiadiazole and the like. These may be used alone or in combination of two or more.

  Examples of the tetrazole compound (E component) used together with the A to D components include 1H-tetrazole, 5,5′-bis-1H-tetrazole, 5-methyl-1H-tetrazole, 5-phenyl-1H-tetrazole, 5 5-amino-1H-tetrazole, 5-mercapto-1H-tetrazole such as 5-mercapto-1H-tetrazole, 1-methyl-1H-tetrazole, 1-phenyl-1H-tetrazole, 1-amino-1H-tetrazole, 1-mercapto 1-substituted 1H-tetrazole such as 1H-tetrazole, 1-phenyl-5-methyl-1H-tetrazole, 1-phenyl-5-amino-1H-tetrazole, 1-phenyl-5-mercapto-1H-tetrazole, etc. Examples include 1-substituted-5-substituted-1H-tetrazole. From the viewpoint of copper oxidation prevention, 1H-tetrazole and 5-substituted-1H-tetrazole are more preferable.

In the present invention, in addition to the above A~E components, more solder heat resistance and bending resistance of the object to further improve a special epoxy resin (F component) Ru is used. Examples of the special epoxy resin (F component) include an epoxy resin represented by the following general formula (2).

Epoxy resin represented by the above general formula (2), for example, it can be produced by the method described in JP 2004-15602 4 JP. Specifically, the bifunctional phenol compound represented by the following formula (4) is reacted with divinyl ether of a hydrocarbon compound containing an ether bond, and then the resulting bifunctional phenol resin is reacted with epihalohydrin. Can be manufactured.

  In the photosensitive resin composition of the present invention, each content of the above components A to E and each content in the case of using the F component in addition to this are preferably set as follows.

  First, the content of the component A is set in the range of 20 to 70 parts of the entire photosensitive resin composition in the photosensitive resin composition of the present invention (100 parts (excluding organic solvents), the same applies hereinafter). Preferably, it is 25 to 65 parts. That is, the photosensitive resin composition of the present invention is essentially rich in alkali developability, but if the component A is less than 20 parts, the alkali developability tends to be insufficient, and exceeds 70 parts. This is because the solder heat resistance tends to be insufficient.

  Moreover, it is preferable to set content of the said B component in the range of 5-50 parts of the whole photosensitive resin composition, More preferably, it is 10-40 parts. That is, if the amount is less than 5 parts, the sensitivity tends to be insufficient, and if it exceeds 50 parts, the alkali developability tends to decrease.

  It is preferable to set content of the said C component in the range of 0.1-10 parts of the whole photosensitive resin composition, More preferably, it is 0.2-8 parts. That is, if the amount is less than 0.1 part, the sensitivity tends to be insufficient, and if it exceeds 10 parts, the alkali developability tends to decrease.

  Moreover, it is preferable to set content of the said D component in the range of 0.01-5 parts of the whole photosensitive resin composition, More preferably, it is 0.02-3 parts. That is, if the amount is less than 0.01 part, the solder heat resistance tends to be insufficient, and if it exceeds 5 parts, the contamination of the plating solution increases, and there is a tendency to adversely affect the plating quality.

  Furthermore, it is preferable to set content of the said E component in the range of 0.01-5 parts of the whole photosensitive resin composition, More preferably, it is 0.02-3 parts. That is, if the amount is less than 0.01 part, the plating riding uniformity of the opening is lowered, and if it exceeds 5 parts, the contamination of the plating solution increases and the plating quality tends to be adversely affected.

  The content of the F component is preferably set to 40 parts or less of the entire photosensitive resin composition from the viewpoint of alkali developability. More preferably, it is 2 to 30 parts. That is, if the amount is less than 2 parts, the folding resistance tends to decrease, and if it exceeds 30 parts, the alkali developability tends to slightly decrease.

  In the photosensitive resin composition of the present invention, in addition to the above components, other additives, that is, pigments such as phthalocyanine green and phthalocyanine blue, fillers such as silica, barium sulfate, and talc, antifoam Agents, leveling agents, flame retardants, stabilizers, adhesion-imparting agents, rust preventive agents such as benzotriazole, epoxy resins other than the above F component, thermal crosslinking agents such as blocked isocyanate, and the like can be appropriately blended. These may be used alone or in combination of two or more. And it is preferable to use these other additives within the range of 0.01-20 parts of the whole photosensitive resin composition.

  The photosensitive resin composition of the present invention is obtained by blending and mixing each of the above components so as to have a predetermined content, and usually exhibits a liquid state and is polymerized to form a flexible solid weight. Combined. And the photosensitive resin composition (before superposition | polymerization) of this invention can be mixed and used for an organic solvent as needed. The organic solvent is not particularly limited, and examples thereof include diethylene glycol monoethyl ether acetate, diethylene glycol monobutyl ether acetate, diethylene glycol monoethyl ether, diethylene glycol monomethyl ether, solvent naphtha, N-methylpyrrolidone, γ-butyrolactone, and butyl cellosolve. , Ethyl cellosolve, methyl cellosolve, toluene, xylene, mesitylene, acetone, methyl ethyl ketone, methyl isobutyl ketone, or a mixed solvent thereof can be used.

  Although the usage-amount in the case of using the said organic solvent is not specifically limited, About 0-200 parts of the whole photosensitive resin composition can be mixed and used.

  The photosensitive resin composition of the present invention is useful as, for example, a solder resist material for printed circuit boards such as flexible printed wiring boards, and can also be used for applications such as paints, coating agents, and adhesives.

  When used as a solder resist material for the printed circuit board, for example, it is used as follows. Hereinafter, a flexible printed wiring board will be described as an example.

  Since the photosensitive resin composition of the present invention is in a liquid state, it can be easily dried on a conductive circuit pattern forming surface of a flexible printed wiring board by a screen printing method, a spray method, a roll coating method, an electrostatic coating method, or the like. Can be applied to a thickness of 5 to 50 μm, and after the coating film is dried at 5 to 120 ° C. for about 3 to 60 minutes, the negative or positive mask pattern film is brought into direct contact with the coating film, or The exposed portion can be cured (polymerized) by placing it without contact and then irradiating it with an actinic ray for exposure.

  As the light source of the actinic ray, various known light sources such as a carbon arc lamp, a mercury vapor arc lamp, an ultrahigh pressure mercury lamp, a high pressure mercury lamp, a xenon lamp, etc. that effectively irradiate ultraviolet rays are used. Moreover, what irradiates effectively visible light, such as a photographic flood light bulb, a solar lamp, a metal halide lamp, and a low pressure mercury lamp, is also used.

  Next, using a developing solution such as an alkaline aqueous solution, the unexposed portion is removed and developed by a known method such as spraying, rocking dipping, brushing, scraping, etc. to produce a resist pattern.

  Examples of the alkaline aqueous solution used for the development include a dilute solution of 0.1 to 5 wt% sodium carbonate, a dilute solution of 0.1 to 5 wt% potassium carbonate, a dilute solution of 0.1 to 5 wt% sodium hydroxide, 0 A dilute solution of 1 to 5% by weight sodium tetraborate or the like can be used.

In addition, after development, for the purpose of improving solder heat resistance, chemical resistance, etc., ultraviolet irradiation or heating with a high-pressure mercury lamp can be performed as necessary. The irradiation amount of the ultraviolet rays is preferably set to about 0.2 to 10 J / cm ² , and the heating is preferably performed in the range of about 100 to 180 ° C. for 15 to 120 minutes. Either the ultraviolet irradiation or heating may be performed first, or only one of ultraviolet irradiation and heating may be performed.

  The flexible printed wiring board on which the solder resist is formed in this manner is then mounted by mounting electronic components such as LSI, diodes, transistors, capacitors, etc. by soldering or the like, for example, small devices such as mobile phones Etc. will be mounted.

  Next, examples will be described together with comparative examples.

  First, prior to the examples and comparative examples, the following component materials were prepared.

A. Synthesis of linear polymer containing carboxyl group (component A)
(1) Synthesis of polymer a 70 g of diethylene glycol monoethyl ether acetate was placed in a 300 ml separable flask under a nitrogen atmosphere and heated to 100 ° C. with stirring. After incubating for 30 minutes, a solution in which 20 g of phenoxyethyl acrylate, 20 g of methacrylic acid, 60 g of methyl methacrylate, 100 g of diethylene glycol monoethyl ether acetate and 1.6 g of azobisisobutyronitrile as a catalyst were mixed and dissolved was separated over 3 hours. The reaction was dropped into the flask. After incubating at 100 ° C. for 2 hours, the mixture was cooled to obtain a polymer solution a (solid content: 50% by weight, Mw = 15000).

(2) Synthesis of Polymer b 70 g of diethylene glycol monoethyl ether acetate was placed in a 300 ml separable flask under a nitrogen atmosphere and heated to 100 ° C. with stirring. After incubating for 30 minutes, a solution in which 20 g of phenoxyethyl acrylate, 20 g of methacrylic acid, 60 g of methyl methacrylate, 100 g of diethylene glycol monoethyl ether acetate and 0.4 g of azobisisobutyronitrile as a catalyst were mixed and dissolved was separated over 3 hours. The reaction was dropped into the flask. After incubating at 100 ° C. for 2 hours, the mixture was cooled to obtain a polymer solution b (solid content: 50% by weight, Mw = 45000).

(3) Synthesis of Polymer c 70 g of diethylene glycol monoethyl ether acetate was placed in a 300 ml separable flask under a nitrogen atmosphere and heated to 90 ° C. with stirring. After incubating for 30 minutes, a solution in which 20 g of phenoxyethyl acrylate, 20 g of methacrylic acid, 60 g of methyl methacrylate, 100 g of diethylene glycol monoethyl ether acetate and 0.4 g of azobisisobutyronitrile as a catalyst were mixed and dissolved was separated over 3 hours. The reaction was dropped into the flask. The mixture was kept at 90 ° C. for 2 hours and then cooled to obtain a polymer solution c (solid content: 50% by weight, Mw = 50000).

(4) Synthesis of Polymer d 173 g of diethylene glycol monoethyl ether acetate was placed in a 500 ml separable flask under a nitrogen atmosphere and heated to 140 ° C. with stirring. After incubating for 30 minutes, a solution in which 60 g of phenoxyethyl acrylate, 20 g of methacrylic acid, 20 g of methyl methacrylate, 203 g of diethylene glycol monoethyl ether acetate and 1.6 g of azobisisobutyronitrile as a catalyst were mixed and dissolved was separated over 3 hours. The reaction was dropped into the flask. The mixture was kept at 140 ° C. for 2 hours and then cooled to obtain a polymer solution d (solid content: 33% by weight, Mw = 5000).

(3) Synthesis of Polymer e 70 g of diethylene glycol monoethyl ether acetate was placed in a 300 ml separable flask under a nitrogen atmosphere and heated to 100 ° C. with stirring. After incubating for 30 minutes, a solution in which 20 g of phenoxyethyl acrylate, 20 g of methacrylic acid, 60 g of methyl methacrylate, 100 g of diethylene glycol monoethyl ether acetate and 0.2 g of azobisisobutyronitrile as a catalyst were mixed and dissolved was separable over 3 hours. The reaction was dropped into the flask. After incubating at 100 ° C. for 2 hours, the mixture was cooled to obtain a polymer solution e (solid content: 50% by weight, Mw = 60000).

(4) Synthesis of Polymer f 173 g of diethylene glycol monoethyl ether acetate was placed in a 500 ml separable flask under a nitrogen atmosphere and heated to 150 ° C. with stirring. After incubating for 30 minutes, a solution in which 60 g of phenoxyethyl acrylate, 20 g of methacrylic acid, 20 g of methyl methacrylate, 203 g of diethylene glycol monoethyl ether acetate and 1.6 g of azobisisobutyronitrile as a catalyst were mixed and dissolved was separated over 3 hours. The reaction was dropped into the flask. After incubating at 150 ° C. for 2 hours, the mixture was cooled to obtain a polymer solution f (solid content: 33% by weight, Mw = 4500).

  The composition ratios of the blending components, the polymerization temperature, and the weight average molecular weight in each of the polymer solutions a to f thus obtained are also shown in Table 1 below.

B. Ethylenically unsaturated group-containing polymerizable compound (component B)
As an ethylenically unsaturated group-containing polymerizable compound, BPE500 manufactured by Shin-Nakamura Chemical Co., Ltd. and ethylene oxide-modified bisphenol A methacrylate [p + q = 10 in the above formula (3)] were prepared.

C. Photopolymerization initiator (component C)
As a photopolymerization initiator, Irgacure369 manufactured by Ciba Geigy Corporation was prepared.

D. Heterocyclic mercaptan compound (component D)
As a heterocyclic mercaptan compound, 2-amino-5-mercapto-1,3,4-thiadiazole and 2,5-dimercapto-1,3,4-thiadiazole were prepared.

E. Tetrazole compound (E component)
5-Amino-1H-tetrazole, 1H-tetrazole, and 5-methyl-1H-tetrazole were prepared as tetrazole compounds.

F. Epoxy resin (F component)
As an epoxy resin (F component), triethylene glycol divinyl ether-modified bisphenol A type epoxy resin [wherein X in the formula (2) is a di (ethyleneoxy) ethyl group, R _{1 to} R ₂ are methyl groups, and R _{3 to} R ₆ is a hydrogen atom, and the average value of n is 1.2].

G. Epoxy resin other than component (F) As an epoxy resin other than component (F), Epicoat 1010 manufactured by Japan Epoxy Resin Co., Ltd. and bisphenol A type epoxy resin (weight average molecular weight of about 5500) were prepared.

H. Pigment Phthalocyanine green was prepared as a pigment.

[ Reference Example 1, Examples 1-6 , Comparative Examples 1-5]
A photosensitive resin composition was prepared by blending and mixing each of the above-described component raw materials in the proportions shown in Tables 2 to 3 below (the numbers in the table are parts by weight of the nonvolatile content (solid content)). is there).

  Characteristic evaluation was performed according to the method shown below using each photosensitive resin composition thus obtained. The results are also shown in Tables 4 to 5 below.

[Folding resistance]
Prepare a flexible printed wiring board in which a linear copper pattern with a thickness of 18 μm and L / S (pattern width / pattern interval) = 50 μm / 50 μm is directly formed on a polyimide film with a thickness of 25 μm. The copper surface was leveled. Thereafter, the photosensitive resin composition solution is applied onto the flexible printed wiring board so that the thickness after drying is 20 μm, dried (80 ° C. × 30 minutes), and further, the thickness of 38 μm is further formed thereon. The polyethylene film was brought into close contact, and irradiated with ultraviolet rays at an exposure amount of 300 mJ / cm ² with a 250 W ultrahigh pressure mercury lamp. Thereafter, the polyethylene film was peeled off, and heat treatment was performed at 150 ° C. for 30 minutes in a hot air circulating dryer.

The flexible printed wiring board thus provided with the photosensitive resin composition layer is bent 180 ° in the direction parallel to the copper circuit pattern with the copper circuit pattern facing outward, and the photosensitive resin composition of the bent portion The occurrence of cracks in the material layer was visually evaluated according to the following criteria.
(Double-circle): The crack did not generate | occur | produce at all.
○: Almost no cracks occurred.
X: A crack occurred.

[Alkali developability]
After degreasing, the above photosensitive resin composition solution was applied on a 35 μm thick copper foil whose surface was smoothed by soft etching, and dried (80 ° C. × 30 minutes) so that the thickness after drying was 20 μm. Further, a 38 μm thick polyethylene film was further adhered thereon, and irradiated with ultraviolet rays at an exposure amount of 300 mJ / cm ² with a 250 W ultrahigh pressure mercury lamp. Thereafter, the polyethylene film was peeled off and developed for 90 seconds at a pressure of 0.2 MPa using a 1 wt% aqueous sodium carbonate solution at 30 ° C. The unexposed part after development was visually observed and evaluated according to the following criteria.
○: There was no residue of the photosensitive resin composition.
X: There was a residue of the photosensitive resin composition.

[Uniformity of plating ride]
A two-layer base material for flexible printed wiring boards in which a copper layer having a thickness of 18 μm was directly formed on a polyimide film was degreased and soft etched to level the copper surface. Next, on the copper layer, the photosensitive resin composition solution was applied so as to have a thickness after drying of 20 μm, and dried (80 ° C. × 30 minutes) to form a coating film. A polyethylene film having a mold release treatment of 38 μm in thickness was brought into close contact therewith, and in that state, ultraviolet rays were irradiated through a glass mask provided with a square negative pattern having a side of 5 mm with a high-pressure mercury lamp at an exposure amount of 300 mJ / cm ² . Thereafter, the polyethylene film is peeled off, developed with a 1 wt% aqueous sodium carbonate solution (30 ° C.) at a pressure of 0.2 MPa for 90 seconds, washed with ion-exchanged water for 30 seconds, and then heated at 150 ° C. in a hot air circulating dryer. A heat treatment was performed for 30 minutes to prepare a plating ride evaluation substrate in which an opening exposing the copper surface was formed. The substrate for evaluation was subjected to electroless Ni / Au plating, and the plating riding uniformity was evaluated according to the following criteria.
○: The plating surface gloss is uniform by visual observation.
X: The plating surface gloss is nonuniform by visual observation.

[Insulation]
A flexible printed wiring board in which a comb-shaped copper pattern for bias test having a thickness of 18 μm and L / S (pattern width / pattern interval) = 50 μm / 50 μm is formed on a polyimide film having a thickness of 25 μm is prepared. The copper surface was leveled by soft etching. Thereafter, the photosensitive resin composition solution is applied onto the flexible printed wiring board so as to have a thickness after drying of 20 μm and dried (80 ° C. × 30 minutes), and further, a thickness of 38 μm is formed thereon. The polyethylene film was closely attached, and irradiated with ultraviolet rays at an exposure amount of 300 mJ / cm ² with a 250 W ultrahigh pressure mercury lamp. Thereafter, the polyethylene film is peeled off, developed with a 1 wt% sodium carbonate aqueous solution (30 ° C.) at a pressure of 0.2 MPa for 90 seconds, washed with ion-exchanged water for 30 seconds, and then heated at 150 ° C. in a hot air circulating dryer. A heat treatment was performed for 30 minutes to produce a printed wiring board for insulation test. This insulation test printed wiring board is put into a constant temperature and humidity chamber of 85 ° C. × 85% RH, a voltage of 50 V is applied between both electrodes of the comb pattern, and the insulation resistance is measured in the chamber until 1000 hours have passed. Then, the following criteria were evaluated.
○: An insulation resistance value of 10 ⁶ Ω or more even after 1000 hours.
X: Insulation resistance value less than 10 ⁶ Ω within 1000 hours.

[Solder heat resistance]
The photosensitive resin composition solution is applied on a copper foil having a thickness of 35 μm, which has been degreased and soft-etched, and dried (80 ° C. × 30 minutes) so that the thickness after drying is 20 μm. Then, a polyethylene film having a thickness of 38 μm was brought into close contact therewith, and was irradiated with ultraviolet rays at an exposure amount of 300 mJ / cm ² with a 250 W ultra-high pressure mercury lamp through a glass mask on which a square negative pattern having a side of 5 mm was formed. Thereafter, the polyethylene film was peeled off, developed with a 1 wt% sodium carbonate aqueous solution at 30 ° C. for 90 seconds at a pressure of 0.2 MPa, washed with ion-exchanged water for 30 seconds, and then heated at 150 ° C. in a hot air circulating dryer. X A heat treatment for 30 minutes was performed to produce a solder heat resistance test substrate.

Next, rosin-based flux MH-820V (manufactured by Tamura Kaken Co., Ltd.) was applied on the substrate, and then immersed in a solder bath at 260 ° C. for 10 seconds to perform a soldering process. Then, it evaluated visually according to the following reference | standard.
A: Solder dive, solder resist float, and peeling did not occur at all.
○: Solder dive, solder resist float and peeling hardly occurred.
X: Solder dive or solder resist float and peeling occurred.

From the above results, it is clear that the example product can provide a flexible printed wiring board that is satisfactory in all of folding resistance, alkali developability, insulation, and solder heat resistance. In particular , the example products using the epoxy resin (F component) had more excellent results regarding solder heat resistance and folding resistance.

  On the other hand, Comparative Examples 1, 2, and 5 were inferior in solder heat resistance, and Comparative Examples 3-5 were inferior in plating riding uniformity. In addition, the comparative example 4 product was inferior in alkali developability.

Claims (4)

The photosensitive resin composition containing the following (A)-( F ) component.
(A) A carboxyl group-containing linear polymer.
(B) An ethylenically unsaturated group-containing polymerizable compound.
(C) Photopolymerization initiator.
(D) A heterocyclic mercaptan compound represented by the following general formula (1).

(E) Tetrazole compound.
(F) An epoxy resin represented by the following general formula (2).

(A) above weight average molecular weight of the carboxyl group-containing linear polymer is a component, the photosensitive resin composition of claim 1 Symbol placement is 5,000 to 50,000. The photosensitive resin composition of Claim 1 or 2 in which the ethylenically unsaturated group containing polymeric compound which is the said (B) component contains the bisphenol A type (meth) acrylate compound represented by following General formula (3). object.

By forming a photosensitive resin composition layer on the conductor circuit pattern using the photosensitive resin composition according to any one of claims 1 to 3 , and exposing and developing the photosensitive resin composition layer to a predetermined pattern. A printed circuit board formed with an insulating cover layer.