JP2007304543A - Photosensitive resin composition, photosensitive film, resist pattern forming method, and printed wiring board and method for manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a photosensitive resin composition capable of forming a resist pattern which satisfies flexibility required when used for a FPC and also has excellent flame retardancy and hot pressing resistance. <P>SOLUTION: The photosensitive resin composition comprises (A) a polymer having a carboxyl group, (B) a photopolymerizable compound having an ethylenically unsaturated bond and containing no halogen atom, (C) a photopolymerization initiator, (D) a phenoxyphosphazene compound, (E) a phosphoric ester compound and (F) a halogen-based flame retardant. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a photosensitive resin composition, a photosensitive film, a method for forming a resist pattern, a printed wiring board, and a method for manufacturing the same.

  As one type of printed wiring board, there is a film-like printed wiring board called a flexible printed circuit board (hereinafter referred to as “FPC”). FPC is used in particular for small devices such as cameras, magnetic heads, and mobile phones. This is because the FPC can maintain its function even when it is bent, and thus is suitable as a printed wiring board to be accommodated in a small device as described above.

  In recent years, requests for further miniaturization and weight reduction of various electronic devices have increased. In addition, by adopting FPC for wiring of electronic equipment, it has been possible to meet demands for miniaturization and weight reduction of equipment, and to reduce product costs and simplify design.

  Conventionally, a photosensitive material such as a liquid photosensitive resin composition or a photosensitive film having a film-like photosensitive layer has been used in the production of printed wiring boards. These photosensitive materials are used, for example, to form an etching resist when etching a copper foil of a copper clad laminate, or a solder resist for limiting or protecting a soldering position of a printed wiring board.

  FPC solder resists are required to satisfy characteristics such as organic solvent resistance, high resolution, insulation, and solder heat resistance in the same way as solder resists used in ordinary printed wiring boards. It is also required to have flexibility so as not to be broken when folded. Furthermore, in order to make the FPC partly thick or hard, a reinforcing plate may be attached to the FPC by hot pressing, and the solder resist of the FPC flows excessively to the surroundings during processing by the hot pressing. It is required that no exudation occurs. In addition, since most FPCs are used in electronic devices, the solder resist is also required to have flame retardancy.

  At present, coverlays formed by punching a polyimide film with an adhesive are most often used as FPC solder resists because they are relatively good in terms of various characteristics as described above.

  However, in the case of this cover lay, the mold used for die cutting is very expensive, and when the cover lay is laminated, it is manually aligned and bonded, so that the manufacturing cost is low. There is a problem that it becomes high. Furthermore, formation of a fine pattern is important in order to achieve the purpose of adopting an FPC that meets the demand for miniaturization of electronic equipment, but there is also a problem that it becomes difficult to form a fine pattern when a coverlay is used. .

  In order to solve these problems, a liquid containing an unsaturated group-containing polycarboxylic acid resin obtained by reacting an addition product of a specific epoxy resin and an unsaturated monocarboxylic acid with succinic anhydride or the like. Ink compositions for FPC have been proposed (see, for example, Patent Document 1 and Patent Document 2).

  Further, for the purpose of forming a flexible solder resist, a reaction product obtained by reacting a mixture of a novolak epoxy resin and a rubber-modified bisphenol A type epoxy resin with an ethylenically unsaturated carboxylic acid, and the above mixture A liquid photosensitive resin composition characterized by containing a reaction product obtained by reacting with a polybasic acid or the like has been proposed (see, for example, Patent Document 3).

On the other hand, the film type photosensitive material intended to impart flame retardancy includes those described in Patent Document 4. Patent Document 4 discloses a film made of a photosensitive resin composition containing a specific bromo-substituted monomer and antimony trioxide having a specific particle size or less.
JP-A-7-207211 JP-A-8-134390 Japanese Patent Laid-Open No. 9-5997 Japanese Patent Laid-Open No. 5-27433

  However, the level of flexibility required for FPC is increasing, and conventional liquid FPC ink compositions and photosensitive resin compositions such as those described in Patent Documents 1 to 3 have been used. However, it has become clear that the flexibility currently required for the FPC is not sufficiently satisfied. Further, according to the knowledge of the present inventors, these conventional liquid ink compositions for FPC and photosensitive resin compositions do not sufficiently satisfy the heat-resistant press properties and flame retardancy required for FPC. .

  Furthermore, the present inventors have found that the film-like photosensitive material described in Patent Document 4 has room for improvement in terms of flexibility. This is considered to be mainly due to the incorporation of antimony trioxide in the material for imparting flame retardancy.

  The present invention has been made in view of the above circumstances, and provides a resist pattern that sufficiently satisfies the flexibility required when used in an FPC, and that is sufficiently excellent in flame retardancy and heat-resistant pressability. It aims at providing the photosensitive resin composition which can be formed.

  The photosensitive resin composition according to the present invention includes (A) a polymer having a carboxyl group, (B) a photopolymerizable compound having an ethylenically unsaturated bond and containing no halogen atom, and (C) a photopolymerization initiator. , (D) a phenoxyphosphazene compound, (E) a phosphoric ester compound, and (F) a halogen-based flame retardant.

  By combining these specific components, the photosensitive resin composition according to the present invention sufficiently satisfies the flexibility required when used in an FPC, and also has flame retardancy and heat press resistance. A sufficiently excellent resist pattern can be formed.

  The total content of (D) and (E) is preferably 3 to 50 parts by weight with respect to 100 parts by weight of the total amount of (A) and (B). Thereby, the heat-resistant press property of the resist pattern formed is further improved.

  (D) is preferably a phenoxyphosphazene compound having a cyclic structure represented by the following general formula (1a) or an acyclic structure represented by the following general formula (1b). In the formula (1a), n represents an integer of 2 to 20, and in the formula (1b), m represents an integer of 1 to 20.

  (E) is preferably a phosphate compound represented by the following general formula (2). In formula (2), R represents a hydrogen atom or an alkyl group having 1 to 10 carbon atoms, and a plurality of R in the same molecule may be the same or different.

  (A) is preferably a copolymer having (meth) acrylic acid as a monomer unit and optionally having an ethylenically unsaturated bond. Moreover, it is preferable that the acid value of (A) is 90-200 mgKOH / g, and the glass transition temperature of (A) is 40-80 degreeC.

  The molecular weight of (B) is preferably 200-5000. Moreover, it is preferable that content of (B) is 10-80 weight part with respect to 100 weight part of total amounts of (A) and (B).

  The content of (F) is preferably 60 to 90 parts by weight with respect to 100 parts by weight of the total amount of (A) and (B).

  The photosensitive resin composition is particularly useful when used for forming a permanent resist.

  The photosensitive film which concerns on this invention is equipped with a support body and the photosensitive layer which consists of one of the said photosensitive resin compositions formed on this support body. The photosensitive film may further include a peelable protective film provided on the surface of the photosensitive layer opposite to the support.

  The method for forming a resist pattern according to the present invention includes a step of laminating a photosensitive layer made of any one of the above photosensitive resin compositions on a substrate, irradiating a predetermined portion of the laminated photosensitive layer with actinic rays, Removing a part of the photosensitive layer to form a resist pattern. Alternatively, a method for forming a resist pattern according to the present invention, a step of laminating the photosensitive layer of the photosensitive film on a substrate, irradiating a predetermined portion of the laminated photosensitive layer with actinic rays, and then a part of the photosensitive layer And a step of forming a resist pattern.

  In the above method, the substrate has an insulating base material and a conductor layer formed on the insulating base material, and a resist pattern is formed so that an opening exposing a part of the conductor layer is formed. It is preferable to do. The conductor layer is preferably patterned so that a circuit pattern is formed.

  The printed wiring board according to the present invention includes a resist pattern formed by the above method as a permanent resist. This printed wiring board uses a resist pattern made of a photocured product of a photosensitive resin composition as a permanent resist. Since this permanent resist is excellent in flame retardancy, electrical insulation and mechanical strength, a highly reliable printed wiring board can be realized.

  According to the photosensitive resin composition of the present invention, a resist pattern that sufficiently satisfies the flexibility required when used in an FPC and that is sufficiently excellent in flame retardancy and heat-resistant pressability is formed. It is possible. Moreover, the resist pattern formed from the photosensitive resin composition according to the present invention is excellent in insulation resistance and mechanical strength, and is very useful as an insulating resin or solder resist for printed wiring boards. Furthermore, the photosensitive resin composition of the present invention is sufficiently excellent in developability, insulation and solder heat resistance, and is extremely useful as a permanent resist for FPC.

  By using the resist pattern formed by the method according to the present invention, etching or plating can be performed with high accuracy, and high density of the printed wiring board can be effectively realized.

  Hereinafter, preferred embodiments of the present invention will be described in detail. However, the present invention is not limited to the following embodiments. In the present specification, “(meth) acrylic acid” means acrylic acid and methacrylic acid corresponding thereto, “(meth) acrylate” means acrylate and methacrylate corresponding thereto, and “(meth) acryloyl group” "Means an acryloyl group and the corresponding methacryloyl group.

  The photosensitive resin composition according to this embodiment includes (A) a polymer having a carboxyl group, (B) a photopolymerizable compound having an ethylenically unsaturated bond and containing no halogen atom, and (C) photopolymerization initiation. Agent, (D) a phenoxyphosphazene compound, (E) a phosphoric ester compound, and (F) a halogen-based flame retardant.

  The component (A) is a polymer having one or more carboxyl groups. The photosensitive resin composition contains 1 type, or 2 or more types of (A) component. The component (A) is typically a copolymer having (meth) acrylic acid as a monomer unit. This copolymer may have an ethylenically unsaturated bond in the side chain and / or terminal. The copolymer is preferably a copolymer of (meth) acrylic acid, (meth) acrylic acid alkyl ester and copolymerized vinyl monomer.

  The (meth) acrylic acid ester is an ester compound formed from (meth) acrylic acid and an alkyl alcohol having no substituent. Examples of the (meth) acrylic acid alkyl ester include (meth) acrylic acid methyl ester, (meth) acrylic acid butyl ester, and (meth) acrylic acid 2-ethylhexyl.

  The copolymerized vinyl monomer constituting the copolymer is a vinyl monomer that can be copolymerized with (meth) acrylic acid alkyl ester and (meth) acrylic acid. Examples of the copolymerized vinyl monomer include (meth) acrylic acid tetrahydrofurfuryl ester, (meth) acrylic acid dimethylaminoethyl ester, (meth) acrylic acid diethylaminoethyl ester, methacrylic acid glycidyl ester, 2,2,2-trimethyl ester, Examples include fluoroethyl (meth) acrylate, 2,2,3,3-tetrafluoropropyl methacrylate, acrylamide, diacetone acrylamide, styrene, and vinyltoluene.

  A copolymer containing these monomers as monomer units can be obtained by a known polymerization method such as radical polymerization. Moreover, it is also possible to obtain as a commercial item.

  An ethylenically unsaturated bond may be introduced into the side chain or terminal of the copolymer via an ester bond, a urethane bond or the like. The ethylenically unsaturated bond is introduced into the copolymer by, for example, a method of copolymerizing a monomer having an ethylenically unsaturated bond. Examples of the monomer having an ethylenically unsaturated bond include UA-11 and UA-13 (both manufactured by Shin-Nakamura Chemical Co., Ltd., trade names), which are monomers having a urethane bond and an acrylate group. Alternatively, an ethylenically unsaturated bond is introduced through an ester bond by a method in which a carboxyl group in the copolymer is reacted with a monomer having a glycidyl group and an ethylenically unsaturated bond.

  (A) It is preferable that the acid value of a component is 90-200 mgKOH / g, and it is more preferable that it is 100-180 mgKOH / g. If the acid value is less than 90 mgKOH / g, the resolution tends to be lowered, and if it exceeds 200 mgKOH / g, the electric corrosion resistance of the resist tends to be lowered.

  The glass transition temperature (Tg) of the component (A) is preferably 40 to 80 ° C, and more preferably 45 to 70 ° C. When Tg is less than 40 ° C., the tack after forming the coating film is increased, and workability during lamination is reduced. When Tg exceeds 80 ° C., the flexibility of the formed resist pattern tends to decrease.

  The content of the component (A) is preferably 20 to 90 parts by weight and more preferably 30 to 80 parts by weight when the total amount of the components (A) and (B) is 100 parts by weight. preferable. If this amount is less than 20 parts by weight, the tackiness of the surface at the time of coating film formation, cracking of the coating film, developability, and solder heat resistance tend to decrease, and if it exceeds 90 parts by weight, the sensitivity of the photosensitive resin composition. Tends to decrease.

  The component (B) used in the present embodiment is a photopolymerizable compound having an ethylenically unsaturated bond. This photopolymerizable compound is a copolymer or monomer having an ethylenically unsaturated bond that is polymerized by the action of light or a photopolymerization initiator. The photopolymerizable compound may have any structure such as aliphatic, aromatic, alicyclic and heterocyclic rings. The photopolymerizable compound may have an ester bond, a urethane bond or an amide bond. However, the photopolymerizable compound having a halogen atom is used as the (F) halogen flame retardant described later. That is, the component (B) is a photopolymerizable compound having no halogen atom. The photosensitive resin composition contains 1 type, or 2 or more types of (B) component.

  The component (B) preferably has an acryloyl group or a methacryloyl group as a functional group having an ethylenically unsaturated bond.

  As a photopolymerizable compound having an acryloyl group, it is formed from acrylic acid, an acrylic acid ester having a hydroxyl group such as hydroxylethyl acrylate and hydroxylpropyl acrylate, an aliphatic alcohol such as methyl acrylate and butyl acrylate, and acrylic acid. Acrylic acid ester, acrylic acid ester formed from an alcohol having a heterocyclic ring such as isocyanurate ring and acrylic acid, acrylic acid ester having an epoxy group such as glycidyl acrylate, ethylene glycol diacrylate, polypropylene glycol acrylate, Acrylic esters of polyhydric alcohols such as methylolpropane triacrylate and ethoxylated trimethylolpropane triacrylate, tetrahydrofurfryl acrylate Acrylic acid ester having a cyclic ether structure, diglycidyl etherified epoxy acrylate acrylic acid added bisphenols include acrylic-modified novolak type epoxy resin having acrylic acid added to the novolak type epoxy resin.

  As a photopolymerizable compound having a methacryloyl group, it is formed from methacrylic acid, a methacrylic acid ester having a hydroxyl group such as hydroxylethyl methacrylate and hydroxylpropyl methacrylate, an aliphatic alcohol such as methyl methacrylate and butyl methacrylate, and methacrylic acid. Methacrylic acid esters, methacrylic acid esters formed from methacrylic acid and alcohols having a heterocyclic ring such as isocyanurate ring, methacrylic acid esters having an epoxy group such as glycidyl methacrylate, ethylene glycol dimethacrylate, polypropylene glycol methacrylate, Methacrylates of polyhydric alcohols such as methylolpropane trimethacrylate and ethoxylated trimethylolpropane trimethacrylate, Methacrylic acid ester having cyclic ether structure such as trahydrofurfuryl methacrylate, epoxy methacrylate in which methacrylic acid is added to diglycidyl etherified product of bisphenol, and methacrylic modified novolak type epoxy resin in which methacrylic acid is added to novolac type epoxy resin Can be mentioned.

  Photopolymerizable compounds obtained by adding (meth) acrylic acid to the epoxy group, such as epoxy acrylate and methacryl-modified novolak type epoxy resins, are within the range in which properties such as resolution and moisture resistance insulation are not significantly impaired. The hydroxyl group may be modified by reaction with a saturated and / or carboxylic anhydride.

  The content of the component (B) is preferably 10 to 80 parts by weight and more preferably 20 to 70 parts by weight when the total amount of the component (A) and the component (B) is 100 parts by weight. preferable. If the amount of the component (B) is less than 10 parts by weight, the sensitivity of the photosensitive resin composition tends to decrease, and if it exceeds 80 parts by weight, the tackiness of the surface at the time of coating film formation, cracking of the coating film, developability And there is a tendency that it is not sufficient in terms of solder heat resistance.

  The molecular weight of the component (B) is preferably 200 to 5000, and more preferably 300 to 2000. If the molecular weight is less than 200, the tackiness of the photosensitive resin composition tends to increase, and if it exceeds 5000, the molar concentration of ethylenically unsaturated bonds in the photosensitive resin composition decreases, and the photosensitive resin. The sensitivity of the composition tends to decrease.

  Component (C) is a photopolymerization initiator. (C) component is suitably selected according to the light wavelength etc. of the exposure machine to be used. Examples of the photopolymerization initiator include a radical photopolymerization initiator and a cationic photopolymerization initiator that generates a Lewis acid by light irradiation.

  Specific examples of the radical photopolymerization initiator include acetophenone, benzophenone, 4,4-bisdimethylaminobenzophenone, 4,4-bisdiethylaminobenzophenone, 3,3-dimethyl-4-methoxybenzophenone, benzoin ethyl ether, benzoin butyl ether. Benzoin isobutyl ether, 2,2-dimethoxy-2-phenylacetophenone, 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2-dimethoxy-1-phenylpropan-1-one, 1- (4-isopropylphenyl) -2 -Hydroxy-2-methylpropane, azobisisobutylnitrile, 2-methylthioxanthone, 2,4-diethylthioxanthone, 2,4-diisopropylthioxanthone, 2,4-dimethylthioxanthone, Tilbenzoyl formate, 3,3,4,4-tetra (t-butylperoxycarbonyl) benzophenone, 1,2-di-9-acridinylethane, 1,3-di-9-acridinylpropane, 1,4-di-9-acridinylbutane, 1,7-di-9-acridinylheptane and 1,8-di-9-acridinyloctane.

  Specific examples of the cationic photopolymerization initiator include triphenyl sulfone hexafluoroantimonate, triphenyl sulfone hexafluorophosphate, p-methoxybenzenediazonium hexafluorophosphate, p-chlorobenzenediazonium hexafluorophosphate, diphenyliodonium hexa Fluorophosphate, 4,4-di-t-butylphenyliodonium hexafluorophosphate, and (1-6-n-cumene) (n-dicopentadiniel) iron hexafluorophosphate.

  The content of the component (C) is preferably 0.1 to 10% by mass, and 0.5 to 5.0% by mass with respect to the total solid content of each component in the photosensitive resin composition. It is more preferable.

  The component (D) is a phenoxyphosphazene compound. The phenoxyphosphazene compound includes a structure represented by the following general formula (10). The photosensitive resin composition contains 1 type, or 2 or more types (D) component.

  More specifically, the component (D) is a phenoxyphosphazene oligomer having a cyclic structure represented by the general formula (1a) or an acyclic structure represented by (1b). Formula (1a) represents the cyclic structure comprised by connecting the structure of said Formula (10) continuously. In formula (1a), m is an integer of 2-20, Preferably it is 3-15. N in Formula (1b) is an integer of 1-20, Preferably it is 2-15.

  As the phenoxyphosphazene oligomer represented by the formula (1a) or (1b), for example, SPS-100, SPB-100 and SPE-100 (all manufactured by Otsuka Chemical Co., Ltd., trade names) are commercially available. It is.

  (E) A component is a phosphate ester compound which has a phosphate ester group. (E) As a component, the compound represented by the said General formula (2) is preferable. In Formula (2), R is a hydrogen atom or a C1-C10 alkyl group, Preferably it is a methyl group. The photosensitive resin composition contains 1 type, or 2 or more types of (E) component. As for the phosphoric acid ester compound of the formula (2), for example, CR-747 (manufactured by Daihachi Chemical Industry Co., Ltd., trade name) is commercially available.

  The total content of the component (D) and the component (E) is preferably 3 to 50 parts by weight with respect to 100 parts by weight of the total amount of the components (A) and (B), and 5 to 45 parts by weight. It is more preferable that If this amount is less than 3 parts by weight, the flame resistance and plasticity of the resist pattern to be formed tend to decrease, and if it exceeds 50 parts by weight, the tack tends to increase excessively or the heat resistant pressability tends to decrease. .

  The content of the component (E) is preferably 0.1 to 20 parts by weight and more preferably 0.2 to 10 parts by weight with respect to 1 part by weight of the component (D).

  The component (F) is a halogen flame retardant composed of a compound containing a halogen atom. This halogen flame retardant may be provided with reactivity. The photosensitive resin composition contains 1 type, or 2 or more types of (F) component.

  The halogen-based flame retardant is, for example, a compound having one or two or more halogenated aromatic rings. In this case, a plurality of halogenated aromatic rings in the same molecule may be the same or different. Examples of the halogenated aromatic ring include bromobenzene rings having 1 to 5 bromine atoms such as dibromophenylene, tribromophenyl and pentabromophenyl.

  The halogen flame retardant may be a photopolymerizable compound containing a halogen atom and having an oxyalkylene group such as an oxyethylene group. In this case, the number of repeating units of the oxyalkylene group is preferably 1 to 10, more preferably 1 to 5, and still more preferably 1 to 3.

  Examples of the halogen-based flame retardant having an oxyalkylene group include bis- (3-methacryloyl-2-hydroxypropyl) ether of tetrabromobisphenol A and bis- (3-acryloxy-2-hydroxypropyl) of tetrabromobisphenol A. Ether, bis- (2-methacrylmethacryloyloxyethyl) ether of tetrabromobisphenol A, bis- (2-acrylmethacryloyloxyethyl) ether of tetrabromobisphenol A, 2-tribromo-phenoxyethyl (meth) acrylate, 2- ( 2-tribromophenoxyethoxy) ethyl (meth) acrylate, tribromophenyl acrylate and pentabromobenzyl (meth) acrylate.

  These photopolymerizable compounds can be synthesized by conventional methods, and can also be obtained as commercial products. As a commercial item, BR-31, GX-6094 (above, Dai-ichi Kogyo Seiyaku make, brand name) is mentioned, for example.

  The content of the component (F) is preferably 60 to 90 parts by weight, and more preferably 65 to 80 parts by weight with respect to 100 parts by weight of the total amount of the components (A) and (B). If this content is less than 60 parts by weight, the flame retardancy tends to decrease, and if it exceeds 90 parts by weight, the plasticity of the film tends to decrease.

  The photosensitive resin composition may contain a thermosetting agent as long as the effects obtained by the present invention are not significantly impaired. A thermosetting agent is a compound which has the effect | action which forms a crosslinked structure in the photosensitive resin composition by heating, Comprising: The compound which does not correspond to any of said (A)-(F) is meant. Examples of thermosetting agents include those that themselves crosslink to form a crosslinked structure, and those that react with the carboxyl group of component (A) to form a crosslinked structure.

  A bismaleimide compound is mentioned as a thermosetting agent which bridge | crosslinks itself by heating. Specific examples of the bismaleimide compound include m-di-N-maleimidylbenzene, bis (4-N-maleimidylphenyl) methane, 2,2-bis (4-N-malemidylphenyl) propane, 2,2-bis (4-N-maleimidyl 2,5-dibromophenyl) propane, 2,2-bis [(4-N-maleimidylphenoxy) phenyl] propane and 2,2-bis [(4-N -Maleimidyl-2-methyl-5-ethyl) phenyl] propane. These bismaleimide compounds may be used alone or in combination. The bismaleimide compound can also be used as a modified product with various resins.

  A block isocyanate compound is mentioned as a thermosetting agent which reacts with the carboxyl group of (A) component by heating and forms a crosslinked structure. Examples of the blocked isocyanate compound include polyisocyanate compounds blocked with a blocking agent such as an alcohol compound, a phenol compound, ε-caprolactam, an oxime compound, and an active methylene compound.

  Examples of blocked polyisocyanate compounds include 4,4-diphenylmethane disissocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, naphthalene 1,5-diisocyanate, o-xylene diisocyanate, m-xylene. Aromatic polyisocyanates such as diisocyanate and 2,4-tolylene dimer, aliphatic polyisocyanates such as hexamethylene diisocyanate, 4,4-methylenebis (cyclohexyl isocyanate) and isophorone diisocyanate, and alicyclic polyisocyanates such as bicycloheptane triisocyanate Isocyanates. An aromatic polyisocyanate is preferable from the viewpoint of heat resistance, and an aliphatic polyisocyanate or an alicyclic polyisocyanate is preferable from the viewpoint of preventing coloring.

  The photosensitive resin composition may contain a thermosetting resin as long as the effects obtained by the present invention are not significantly impaired. Examples of the thermosetting resin include a copolymer or monomer having a functional group other than an ethylenically unsaturated bond that can be crosslinked by the radical photopolymerization initiator.

  The photosensitive resin composition may contain a thermal polymerization initiator. A well-known thing can be utilized as a thermal-polymerization initiator. Specific examples of thermal polymerization initiators include ketone peroxides such as benzoyl peroxide and methyl ethyl ketone peroxide, alkyl peroxides such as tertiary butyl peroxide, peroxydicarbonates, peroxyketals, and peroxyesters. As well as alkyl peresters.

  The content of the thermal polymerization initiator is preferably 0.1 to 40% by mass and more preferably 0.5 to 30% by mass with respect to the total solid content of each component in the photosensitive resin composition. preferable.

  The photosensitive resin composition may contain a filler as long as the resolution and flame retardancy are not significantly impaired. As fillers, inorganic fine particles such as silica, fused silica, talc, alumina, hydrated alumina, barium sulfate, aluminum hydroxide, magnesium hydroxide, calcium hydroxide, aerosil and calcium carbonate, powdered epoxy resin, powdered polyimide particles and Examples thereof include organic fine particles such as powdered polyfluorinated ethylene fiber particles. These fillers may be subjected to a coupling treatment in advance.

  The filler is dispersed by a known kneading method such as a kneader, ball mill, bead mill, or three rolls.

  The content of the filler is preferably 2 to 20% by mass and more preferably 5 to 15% by mass with respect to the total solid content of each component in the photosensitive resin composition.

  The photosensitive resin composition may further contain other components such as a polymerization stabilizer, a leveling agent, a pigment, a dye, and an adhesion improver. These selections are made under the same considerations as for ordinary photosensitive resin compositions. These addition amounts are within a range in which the characteristics of the photosensitive resin composition are not significantly impaired. Specifically, it is preferably added in a proportion of 0.01 to 10% by mass in the photosensitive resin composition.

  The photosensitive resin composition can be used in the form of a solution diluted with a solvent when forming a resist pattern. Examples of the solvent include ketone compounds such as methyl ethyl ketone, acetone and cyclohexanone, aromatic hydrocarbon compounds such as xylene and toluene, and amide compounds such as N, N-dimethylformamide and N, N-dimethylacetamide. These solvents are used alone or in a mixed system. In order to dissolve the photosensitive resin composition efficiently, ethylene glycol monoethyl ether, ethyl ethoxypropionate, or the like may be used depending on the solubility.

  The amount of the solvent is preferably 10 to 200 parts by weight and more preferably 30 to 100 parts by weight with respect to 100 parts by weight of the photosensitive resin composition. When the amount of the solvent is less than 10 parts by weight, the viscosity of the solution tends to increase and it becomes difficult to mix uniformly, and when the amount of the solvent exceeds 100 parts by weight, the photosensitive layer is formed by decreasing the viscosity. It tends to be difficult to control the thickness of the layer when formed. Also. There is a tendency that the amount of the solvent used increases and the production cost increases.

  FIG. 1 is a cross-sectional view showing an embodiment of a photosensitive element. The photosensitive element 1 shown in FIG. 1 has a configuration in which a support 11, a photosensitive layer 12, and a protective film 13 are laminated in this order.

  The photosensitive layer 12 is formed from the above-described photosensitive resin composition. The thickness of the photosensitive layer 12 is not particularly limited, but is typically in the range of 10 to 150 μm.

  The photosensitive layer 12 is formed, for example, by a method in which a solution obtained by dissolving a photosensitive resin composition in a solvent is applied on the support 11 to a uniform thickness, and the applied solution is heated to remove the solvent. . Application of the solution is performed using a comma coater, a blade coater, a lip coater, a rod coater, a squeeze coater, a reverse coater, a transfer roll coater, or the like.

  The support 11 is a film that functions as a carrier film that supports the photosensitive layer 12 and the protective film 13. As the support 11, for example, a film such as a polyester film, a polyimide film, a polyamideimide film, a polypropylene film, and a polystyrene film is preferably used.

  The support 11 may have a single layer structure or a multilayer structure in which a plurality of films having different compositions are laminated. The surface of the support 11 opposite to the photosensitive layer 12 may be subjected to processing such as embossing and corona processing. Although the thickness in particular of the support body 11 is not restrict | limited, Preferably it is 5-150 micrometers, More preferably, it is 8-20 micrometers, More preferably, it is 10-16 micrometers. If the thickness of the support 11 is less than 5 μm, the support 11 tends to be easily broken when the support 11 is peeled and removed from the photosensitive film 1, and if it exceeds 150 μm, the flexibility of the entire photosensitive film 1 decreases. Thus, when the photosensitive film 1 is laminated on the uneven surface, the followability to the uneven surface tends to decrease.

  The protective film 13 is peeled off before the photosensitive film 1 is laminated. Therefore, as the protective film 13, a film that has flexibility, can be peelably bonded to the photosensitive layer 12, and is not damaged at the temperature of the drying furnace is used. The protective film 13 may be transparent or non-transparent, and may have been subjected to a release treatment.

  The thickness of the protective film is not particularly limited, but is preferably 10 to 30 μm, more preferably 10 to 25 μm, and more preferably 10 to 20 μm in view of the size when wound in a roll shape. Is more preferable.

  Specific examples of the protective film 13 include polyesters such as polyethylene terephthalate, polyolefins such as polymethylpentene, polypropylene and polyethylene, halogen-containing vinyl polymers such as polyvinyl fluoride and polyvinyl chloride, polyamides such as nylon, and celluloses such as cellophane. And films such as polystyrene. Paper such as release paper may be used as the protective film 13.

  Examples of the protective film available as a commercial product include product name E-200H manufactured by Oji Paper Co., Ltd., and product name NF-13 manufactured by Tamapoli Co., Ltd.

  FIG. 2 is a cross-sectional view illustrating an embodiment of a resist pattern forming method and a printed wiring board manufacturing method. In the embodiment shown in FIG. 2, the step of laminating the photosensitive layer 12 on the substrate 20, irradiating a predetermined portion of the laminated photosensitive layer 12 with active light, and then removing a part of the photosensitive layer 12 to form a resist. Forming the pattern 24.

  In the present embodiment, first, a substrate having an insulating base material 22 and conductor layers 21 and 23 formed on the insulating base material 22 is prepared ((a) of FIG. 2). The conductor layer 23 is patterned so that a predetermined circuit pattern is formed. The conductor layer 21 covers the entire surface of the insulating substrate 22 without being patterned. The board | substrate 20 is obtained by the well-known method of etching the single side | surface of a double-sided metal clad laminated board (for example, double-sided copper clad laminated board), for example.

  The photosensitive layer 12 is laminated on the surface of the substrate 20 on the patterned conductor layer 23 side ((b) of FIG. 2). The photosensitive layer 12 is formed by laminating the above-described photosensitive film 1 after peeling off the protective film 13 on the substrate 20 in a direction in which the photosensitive layer 12 is adjacent to the substrate 20 and heating and pressurizing using a hot roll laminator or the like. Laminated by method. After laminating the photosensitive layer 12, the support 11 may be peeled off, or exposure may be performed with the support 11 left.

  Alternatively, the photosensitive layer 12 may be formed by applying a solution of the photosensitive resin composition onto the substrate 20 and heating the applied solution to remove most of the solvent. In this case, examples of the solution application method include a dip coating method, a roll coating method, a flow coating method, a screen printing method, a spray method, and an electrostatic spray method.

  Next, actinic rays are irradiated in an image form through the mask 5 of the laminated photosensitive layer 12, and a part of the photosensitive layer 12 is photocured ((c) in FIG. 2). The mask 5 may be placed directly on the photosensitive layer 12 or may be disposed on the photosensitive layer 12 with a transparent film interposed therebetween.

  As the exposure light source, a well-known light source such as a carbon arc lamp, a mercury vapor arc lamp, an ultrahigh pressure mercury lamp, a high pressure mercury lamp, a xenon lamp, a metal halide lamp, or the like is used. Moreover, what emits visible light effectively, such as a photographic flood light bulb and a solar lamp, is also used.

  Note that an image resin film can be formed on the photosensitive layer 12 by a printing method, a laser drilling method using a carbon dioxide laser, a YAG laser, an excimer laser, or the like.

  After the exposure, portions other than the photocured portion of the photosensitive layer 12 are removed by development using an alkaline aqueous solution as a developer. The remaining photosensitive layer forms a resist pattern 24 having a pattern in which an opening 26 from which a part of the conductor layer 13 is exposed is formed ((d) in FIG. 2). The development is performed by a known method such as spraying, rocking dipping, brushing, scraping or the like. As the developer, an alkali developer is typically used. However, there is no particular limitation on the type as long as it selectively elutes the unexposed part without damaging the exposed part, and depending on the composition of the photosensitive resin composition used, semi-aqueous development It can be appropriately selected from common ones such as a liquid and a solvent developer. For example, an emulsion developer containing water and an organic solvent described in JP-A-7-234524 can be used.

  For example, organic solvents such as propylene glycol monomethyl ether acetate, ethylene glycol ethyl ether acetate, 2,2-butoxyethoxyethanol, butyl lactate, cyclohexyl lactate, ethyl benzoate, and 3-methyl-3-methoxybutyl acetate are used as the organic solvent component. An emulsion developer containing 10 to 40% by weight is particularly useful.

  When an alkali developer is used, an alkaline aqueous solution containing potassium hydroxide, sodium hydroxide, sodium carbonate, potassium carbonate, sodium phosphate, sodium silicate, sodium 4-borate, ammonia, amines, etc. and the above organic An emulsion developer with a solvent can also be used.

After forming the resist pattern 24, post-curing may be further performed by exposure at 1 to 5 J / cm ² and / or heating at 100 to 200 ° C. for 30 minutes to 12 hours.

  As described above, the substrate 20 on which the conductor layer 23 patterned so as to form a circuit pattern is formed on the insulating base material 22 and the opening 26 where a part of the conductor layer 23 is exposed are formed. A printed wiring board 2 having a resist pattern 24 patterned in this manner is obtained.

  Since the opening 26 is formed in the printed wiring board 2, a mounting component such as CSP or BGA can be joined to the conductor layer 24 having a circuit pattern by soldering or the like. That is, so-called surface mounting is possible.

  The resist pattern 24 is made of a cured product of the photosensitive resin composition. The resist pattern 24 functions as a solder resist that prevents solder from adhering to unnecessary portions on the conductor layer when mounting components are joined. In addition, after bonding the mounted components, it functions as a permanent mask for protecting the conductor layer 23. That is, the resist pattern 24 is a permanent resist.

  The resist pattern 24 is suppressed in insulating deterioration under high temperature and high humidity, and is excellent in electric corrosion resistance. Further, discoloration and blistering in the PCT test are also suppressed.

  Etching of the conductor layer or plating on the conductor layer can be performed using the photosensitive resin composition according to the present embodiment and using the resist pattern as a mask. In this case, etching or plating is performed in the opening portion of the resist pattern where the conductor layer is exposed.

  Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the following examples.

1. Preparation Example 1 of Photosensitive Resin Composition Solution
The following materials were mixed to prepare a photosensitive resin composition solution.
(A) Polymer having carboxyl group
A copolymer obtained by copolymerizing methacrylic acid, methyl methacrylate, methyl acrylate and styrene in a weight ratio of 16: 35: 39: 10 (weight average molecular weight 90,000, acid value 104 mg / g, Tg 49.9 ° C.) : 70 parts by weight (solid content)
(B) Photopolymerizable compound having an ethylenically unsaturated bond and containing no halogen atom Urethane bond-containing monomer (UF-TCB-50, manufactured by Kyoei Chemical Co., Ltd., trade name): 30 parts by weight (solid content)
(C) Photopolymerization initiator Irgacure 369 (Ciba Geigy Corp., trade name): 5 parts by weight (D) Phenoxyphosphazene compound SPB-100 (Otsuka Chemical Co., Ltd., trade name): 20 parts by weight (E) Phosphate ester compound CR-747 (trade name, manufactured by Daihachi Chemical Co., Ltd.): 5 parts by weight (F) Halogen-based flame retardant Bromine-containing acrylate having one ethylenically unsaturated bond (BR-31, Daiichi Kogyo Seiyaku Co., Ltd.) Manufactured): 50 parts by weight Bromine-containing acrylate having two ethylenically unsaturated bonds (GX6094, manufactured by Daiichi Kogyo Seiyaku Co., Ltd., trade name) 20 parts by weight (solvent)
Methyl ethyl ketone: 20 parts by weight

Example 2
As a component (A), a copolymer obtained by copolymerizing methacrylic acid, methyl methacrylate, methyl acrylate and styrene in a weight ratio of 18: 32: 40: 10 (weight average molecular weight 90,000, acid value 117 mg / g) , Tg 49.4 ° C.): A photosensitive resin composition solution was prepared in the same manner as in Example 1 except that 70 parts by weight (solid content) was used.

Example 3
(D) The photosensitive resin composition solution was prepared like Example 1 except having used 20 weight part of SPS-100 (made by Otsuka Chemical Co., Ltd., brand name) as a component.

Example 4
A photosensitive resin composition solution was prepared in the same manner as in Example 1 except that the amount of the phenoxyphosphazene compound (SPB-100) was 60 parts by weight and the amount of the phosphate ester compound (CR-747) was 60 parts by weight. Prepared.

Comparative Example 1
A photosensitive resin composition solution was prepared in the same manner as in Example 1 except that the component (D), the phenoxyphosphazene compound (SPB-100), was not used.

Comparative Example 2
(E) The photosensitive resin composition solution was prepared like Example 1 except not having used the phosphoric acid ester compound (CR-747) of a component.
.

2. Evaluation of photosensitive resin composition Each of the prepared photosensitive resin composition solutions was uniformly applied on a 16 μm-thick polyethylene terephthalate film (trade name “G2-16”, manufactured by Teijin Limited) as a support, The coating film was heated and dried at 100 ° C. for about 10 minutes using a convection dryer. Most of the solvent was removed by drying to obtain a photosensitive film in which a photosensitive layer having a film thickness of 38 μm was formed on the support.

The surface of the copper foil of a flexible printed wiring board substrate (trade name “F30VC1” manufactured by Nikkan Kogyo Co., Ltd.) in which an 18 μm-thick copper foil was laminated on a polyimide base material was acid-treated, washed with water, and dried. Next, the photosensitive film obtained above was laminated on a flexible printed wiring board substrate so that the photosensitive layer was in close contact with the copper foil. The lamination is performed using a press-type vacuum laminator (trade name “MVLP-500” manufactured by Meiki Seisakusho Co., Ltd.), a lamination temperature of 60 ° C., a lamination pressure of 0.4 MPa, a degree of vacuum of 10 × 10 ⁴ , a vacuum time of 20 seconds, The pressure time was 20 seconds.

  Using the HMW-201GX type exposure machine manufactured by Oak Manufacturing Co., Ltd. with respect to the laminated photosensitive layer, from the side of the polyethylene terephthalate film with an energy amount such that the number of remaining steps after development of the Topher 21-step tablet is 8.0. Exposure was performed. Thereafter, the polyethylene terephthalate film was peeled off and developed by spraying a 1% by mass aqueous sodium carbonate solution at 30 ° C. for 40 seconds. After development, the film was dried by heating at 80 ° C. for 10 minutes.

Then, the photosensitive layer was irradiated with ultraviolet rays with an energy amount of 1 J / cm ² using an ultraviolet irradiation device manufactured by Oak Manufacturing Co., Ltd., and further heated at 160 ° C. for 60 minutes.

  As described above, an evaluation flexible printed wiring board (evaluation FPC) in which a resist pattern was formed as a cover lay which is a permanent resist on the flexible printed wiring board substrate was obtained. For the FPCs for evaluation produced using the photosensitive resin composition solutions of Examples 1 to 3 and Comparative Examples 1 and 2, the flexibility and the heat press resistance were evaluated as follows.

Flexibility (fold resistance)
The FPC for evaluation was repeatedly folded 180 ° by goblet folding five times, and the occurrence of cracks in the coverlay at that time was visually observed and evaluated according to the following criteria. The evaluation results are shown in Table 1.
“A”: No crack was found in the coverlay “B”: No crack was found in the coverlay

Heat-resistant pressability The evaluation FPC was pressed in the thickness direction for 30 minutes under the conditions of a press temperature of 175 ° C. and a press pressure of 1470 N (150 kgf) using a 30-t hand press machine (manufactured by Toyo Seiki Seisakusho Co., Ltd.). At that time, the presence or absence of the photosensitive resin composition component from the coverlay was visually observed and evaluated according to the following criteria. The evaluation results are shown in Table 1.
“A”: No exudation of photosensitive resin composition component from coverlay “B”: No exudation of photosensitive resin composition component from coverlay

The copper foil of the flame retardant copper foil-clad laminate (manufactured by Nippon Steel Chemical Co., Ltd., trade name “ESPANEX MB”) was removed by etching to obtain a polyimide film having a thickness of 25 μm. A photosensitive film is laminated on both sides of this polyimide film in the same manner as in the case of the above-described evaluation FPC, and the entire surface is exposed and heated under the same conditions as in the case of the evaluation FPC on the photosensitive layer. A sample for flame retardancy evaluation in which a cured photosensitive layer was formed on both sides of the polyimide film was obtained. This flame retardant evaluation sample was subjected to a thin material vertical combustion test based on the UL94 standard. Evaluation was expressed as VTM-0 or VTM-1 based on the UL94 standard. The evaluation results are shown in Table 1.

  As shown in Table 1, Examples 1 to 4 exhibited excellent characteristics in all points of flexibility (folding resistance), heat press resistance, and flame retardancy. In particular, Examples 1-3 in which the total amount of the component (D) and the component (E) is in the range of 3 to 50 parts by weight with respect to 100 parts by weight of the total amount of the components (A) and (B) are as follows: Compared with Example 4, the heat resistant pressability was further improved. On the other hand, Comparative Examples 1 and 2 were not necessarily sufficient in any one of flexibility (folding resistance), heat press resistance, and flame retardancy.

It is sectional drawing which shows one Embodiment of the photosensitive film. It is sectional drawing which shows one Embodiment of the formation method of a resist pattern, and the manufacturing method of a printed wiring board.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Photosensitive film, 2 ... Printed wiring board, 11 ... Support body, 12 ... Photosensitive layer, 13 ... Protective film, 20 ... Board | substrate, 21 ... Conductive layer, 22 ... Insulating base material, 23 ... Conductive layer, 24 ... Permanent resist (resist pattern), 26... Opening.

Claims (20)

(A) a polymer having a carboxyl group,
(B) a photopolymerizable compound having an ethylenically unsaturated bond and containing no halogen atom,
(C) a photopolymerization initiator,
(D) a phenoxyphosphazene compound,
A photosensitive resin composition containing (E) a phosphoric ester compound, and (F) a halogen-based flame retardant.   2. The photosensitive resin according to claim 1, wherein the total content of (D) and (E) is 3 to 50 parts by weight with respect to 100 parts by weight of the total amount of (A) and (B). Composition. The photosensitive of claim 1 or 2, wherein (D) is a phenoxyphosphazene compound having a cyclic structure represented by the following general formula (1a) or an acyclic structure represented by the following general formula (1b). Resin composition.

[In Formula (1a), n represents an integer of 2 to 20, and in Formula (1b), m represents an integer of 1 to 20. ] The photosensitive resin composition as described in any one of Claims 1-3 whose said (E) is a phosphate ester compound represented by following General formula (2).

[In Formula (2), R shows a hydrogen atom or a C1-C10 alkyl group, and several R in the same molecule | numerator may be the same or different. ]   The photosensitivity as described in any one of Claims 1-4 whose said (A) is a copolymer which has a (meth) acrylic acid as a monomer unit and may have an ethylenically unsaturated bond. Resin composition. The acid value of (A) is 90 to 200 mgKOH / g,
The glass transition temperature of (A) is 40 to 80 ° C.
The photosensitive resin composition as described in any one of Claims 1-5.   The photosensitive resin composition as described in any one of Claims 1-6 whose molecular weight of the said (B) is 200-5000.   The photosensitive property as described in any one of Claims 1-7 whose content of said (B) is 10-80 weight part with respect to 100 weight part of total amounts of said (A) and said (B). Resin composition.   The photosensitive property as described in any one of Claims 1-8 whose content of said (F) is 60-90 weight part with respect to 100 weight part of total amounts of said (A) and said (B). Resin composition.   The photosensitive resin composition as described in any one of Claims 1-9 used for formation of a permanent resist.   A photosensitive film provided with a support body and the photosensitive layer which consists of the photosensitive resin composition as described in any one of Claims 1-8 formed on this support body.   The photosensitive film of Claim 11 further equipped with the peelable protective film provided on the surface on the opposite side to the said support body of the said photosensitive layer. Laminating a photosensitive layer comprising the photosensitive resin composition according to any one of claims 1 to 9 on a substrate;
Irradiating a predetermined part of the laminated photosensitive layer with actinic rays, and then removing a part of the photosensitive layer to form a resist pattern;
A method for forming a resist pattern. A step of laminating the photosensitive layer of the photosensitive film according to claim 11 or 12 on a substrate;
Irradiating a predetermined part of the laminated photosensitive layer with actinic rays, and then removing a part of the photosensitive layer to form a resist pattern;
A method for forming a resist pattern. The substrate has an insulating base material and a conductor layer formed on the insulating base material,
The method for forming a resist pattern according to claim 13 or 14, wherein the resist pattern is formed so that an opening from which a part of the conductor layer is exposed is formed.   The method for forming a resist pattern according to claim 15, wherein the conductor layer is patterned so that a circuit pattern is formed.   The method for forming a resist pattern according to any one of claims 13 to 16, wherein the resist pattern is a permanent resist.   A method for manufacturing a printed wiring board, comprising a step of forming a resist pattern on a substrate by the method according to claim 15 or 16.   The manufacturing method of the printed wiring board of Claim 18 provided with the process of etching or plating in the opening part of the resist pattern which the conductor layer has exposed. A printed wiring board comprising a resist pattern formed by the method according to claim 15 or 16 as a permanent resist.

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