JP2019045608A - Photosensitive resin composition - Google Patents

Abstract

To provide a photosensitive resin composition capable of giving a cured product excellent in thermal shock resistance and solder heat resistance without impairing various basic characteristics such as coating film hardness, alkali developability, and coating film appearance.SOLUTION: The photosensitive resin composition contains (A) a carboxyl group-containing photosensitive resin, (B) a block copolymer, (C) a photopolymerization initiator, (D) a reactive diluent, and (E) an epoxy compound. The block copolymer (B) contains (b1) a carboxyl group-containing triblock copolymer, (b2) a triblock copolymer containing no carboxyl group, and (b3) a diblock copolymer.SELECTED DRAWING: None

Description

  The present invention relates to a photosensitive resin composition, in particular, a photosensitive resin composition useful as an insulating film of a circuit board, and a printed wiring board having a film obtained by photocuring the photosensitive resin composition.

  A printed wiring board is used to form a pattern of a conductive circuit on a substrate and to mount an electronic component on the soldering land of the pattern by soldering, and the circuit portion excluding the soldering land is used as a protective film. It is coated with a solder resist film. Thereby, when soldering an electronic component to a printed wiring board, while preventing that a solder adheres to an unnecessary part, it prevents that a circuit conductor is directly exposed to air and is corroded by oxidation or humidity. Do.

  Further, as the wiring density of the printed wiring board is made finer, the photosensitive resin composition to be applied as a protective film is also required to have high resolution and high accuracy, but in recent years, the installation environment of the printed wiring board is also It is becoming stricter, and furthermore, the prevention of the deterioration of the protective film due to the heat history and the heat load is also required.

  Therefore, in order to suppress yellowing due to thermal history, a carboxyl group-containing photosensitive resin, a silicon dioxide powder and / or a metal oxide powder produced by a thermal decomposition method, a photopolymerization initiator, a diluent, and an epoxy A photosensitive resin composition containing a compound and titanium oxide has been proposed (Patent Document 1).

  On the other hand, the protective film of the printed wiring board has thermal shock resistance, that is, a characteristic capable of preventing the occurrence of cracks even when the protective film is repeatedly exposed to a low temperature atmosphere and a high temperature atmosphere, and solder heat resistance further. Improvement may be required. However, in patent document 1, there existed a problem that thermal shock resistance and solder heat resistance were not enough.

JP, 2011-133670, A

  In view of the above circumstances, it is an object of the present invention to provide a photosensitive material capable of obtaining a cured product excellent in thermal shock resistance and solder heat resistance without impairing basic properties such as coating film hardness, alkali developability and coating film appearance. It is an object of the present invention to provide a water-soluble resin composition.

The embodiment of the present invention comprises (A) a carboxyl group-containing photosensitive resin, (B) a block copolymer, (C) a photopolymerization initiator, (D) a reactive diluent, and (E) an epoxy compound. And contains
The (B) block copolymer includes (b1) a carboxyl group-containing triblock copolymer, (b2) a carboxyl group-free triblock copolymer, and (b3) a diblock copolymer. It is a photosensitive resin composition characterized by the above.

  The aspect of this invention is photosensitivity which the said (b1) carboxyl group-containing triblock copolymer contains 4.0 mass parts or more and 13 mass parts or less with respect to 100 mass parts of said (A) carboxyl group-containing photosensitive resin. Resin composition.

  The aspect of this invention is a triblock copolymer which does not contain said (b2) carboxyl group with respect to 100 mass parts of said (b1) carboxyl group containing triblock copolymers, and said (b3) diblock copolymer is said The photosensitive resin composition contains 30 parts by mass or more and 400 parts by mass or less in total.

  The aspect of this invention is a photosensitive resin composition which said (B) block copolymer contains 10 mass parts or more and 20 mass parts or less with respect to 100 mass parts of said (A) carboxyl group-containing photosensitive resin. .

  An embodiment of the present invention is a photosensitive resin composition in which the (D) reactive diluent contains (meth) acrylate of ε-caprolactone modified dipentaerythritol.

  An aspect of the present invention is a photosensitive resin composition in which the (E) epoxy compound contains a glycidyl ester type epoxy resin.

  An aspect of the present invention is a printed wiring board characterized in that the photosensitive resin composition is applied.

  According to the embodiment of the photosensitive resin composition of the present invention, as the (B) block copolymer, (b1) a carboxyl group-containing triblock copolymer, and (b2) a carboxyl group-free triblock copolymer And (b3) a diblock copolymer, a cured product excellent in thermal shock resistance and solder heat resistance without impairing basic properties such as coating film hardness, alkali developability, and coating film appearance. You can get it.

  According to the embodiment of the photosensitive resin composition of the present invention, (b1) the carboxyl group-containing triblock copolymer is 4.0 parts by mass or more and 13 parts by mass with respect to 100 parts by mass of the (A) carboxyl group-containing photosensitive resin By containing the following, it is possible to improve the thermal shock resistance and the solder heat resistance in a well-balanced manner.

  According to the embodiment of the photosensitive resin composition of the present invention, (b1) triblock copolymer containing no carboxyl group and (b3) per 100 parts by mass of the carboxyl group-containing triblock copolymer (b1) By containing the diblock copolymer in a total amount of 30 parts by mass or more and 400 parts by mass or less, the thermal shock resistance and the solder heat resistance can be improved in a well-balanced manner.

  According to the aspect of the photosensitive resin composition of the present invention, the (B) block copolymer is contained in an amount of 10 parts by mass to 20 parts by mass with respect to 100 parts by mass of the (A) carboxyl group-containing photosensitive resin Furthermore, excellent thermal shock resistance and solder heat resistance can be obtained.

  According to the embodiment of the photosensitive resin composition of the present invention, the (D) reactive diluent contains (meth) acrylate of ε-caprolactone modified dipentaerythritol, thereby more reliably achieving thermal shock resistance and solder heat resistance. It can be improved.

  According to the aspect of the photosensitive resin composition of the present invention, the (E) epoxy compound contains a glycidyl ester type epoxy resin, thereby more surely improving the thermal shock resistance without impairing the excellent solder heat resistance. Can.

  Next, the photosensitive resin composition of the present invention will be described below. The photosensitive resin composition of the present invention comprises (A) a carboxyl group-containing photosensitive resin, (B) a block copolymer, (C) a photopolymerization initiator, (D) a reactive diluent, and (E) ) An epoxy compound, wherein the (B) block copolymer is (b1) a carboxyl group-containing triblock copolymer, (b2) a carboxyl group-free triblock copolymer, (b3) And a diblock copolymer.

(A) Carboxyl Group-Containing Photosensitive Resin The carboxyl group-containing photosensitive resin is not particularly limited, and examples thereof include resins containing a carboxyl group and having one or more photosensitive unsaturated double bonds. As a carboxyl group-containing photosensitive resin, for example, acrylic acid or methacrylic acid (hereinafter referred to as “(meth) acrylic acid”) is added to at least a part of the epoxy group of a polyfunctional epoxy resin having two or more epoxy groups in one molecule. Or the like, or a radically polymerizable unsaturated monocarboxylic acid such as epoxy) is reacted to obtain a radically polymerizable unsaturated monocarboxylic acid oxidized epoxy resin such as epoxy (meth) acrylate, and the generated hydroxyl group is a polybasic acid or its Mention may be made of polybasic acid-modified radically polymerizable unsaturated monocarboxylic oxidized epoxy resins such as polybasic acid-modified epoxy (meth) acrylates obtained by reacting an anhydride.

  As the polyfunctional epoxy resin, any epoxy resin having two or more functional groups can be used. Although the epoxy equivalent of a polyfunctional epoxy resin is not specifically limited, 1500 or less is preferable, 1000 or less is more preferable, and 100-500 are especially preferable. Examples of multifunctional epoxy resins include rubber-modified epoxy resins such as biphenyl type epoxy resin, naphthalene type epoxy resin, dicyclopentadiene type epoxy resin, silicone-modified epoxy resin, ε-caprolactone modified epoxy resin, bisphenol A type, bisphenol F type, phenol novolac type epoxy resin such as bisphenol AD type, cresol novolac type epoxy resin such as о-cresol novolac type, bisphenol A novolac type epoxy resin, cyclic aliphatic polyfunctional epoxy resin, glycidyl ester type polyfunctional epoxy resin, Glycidylamine type multifunctional epoxy resin, heterocyclic type multifunctional epoxy resin, bisphenol modified novolac type epoxy resin, multifunctional modified novolac type epoxy resin, phenols and phenolic hydroxyl group Examples thereof include condensation type epoxy resins with aromatic aldehydes. Further, those resins into which a halogen atom such as Br or Cl is introduced may be used. These epoxy resins may be used alone or in combination of two or more.

  The radically polymerizable unsaturated monocarboxylic acid is not particularly limited, and examples thereof include acrylic acid, methacrylic acid, crotonic acid, and cinnamic acid. Acrylic acid and methacrylic acid are preferable. These radically polymerizable unsaturated monocarboxylic acids may be used alone or in combination of two or more.

  The reaction method of the epoxy resin and the radically polymerizable unsaturated monocarboxylic acid is not particularly limited. For example, the epoxy resin and the radically polymerizable unsaturated monocarboxylic acid may be reacted by heating in a suitable diluent. it can.

  The polybasic acid or polybasic acid anhydride is for reacting with the hydroxyl group formed by the reaction of the epoxy resin and the radically polymerizable unsaturated monocarboxylic acid to introduce a free carboxyl group into the resin. The polybasic acid or its anhydride is not particularly limited, and either saturated or unsaturated one may be used. Examples of polybasic acids include succinic acid, maleic acid, adipic acid, citric acid, phthalic acid, tetrahydrophthalic acid, 3-methyltetrahydrophthalic acid, 4-methyltetrahydrophthalic acid, 3-ethyltetrahydrophthalic acid, 4-ethyltetrahydrophthalic acid Ethyl tetrahydrophthalic acid, hexahydrophthalic acid, 3-methylhexahydrophthalic acid, 4-methylhexahydrophthalic acid, 3-ethylhexahydrophthalic acid, 4-ethylhexahydrophthalic acid, methyltetrahydrophthalic acid, methylhexahydro Phthalic acid, endomethylene tetrahydrophthalic acid, methyl endomethylene tetrahydrophthalic acid, trimellitic acid, pyromellitic acid, diglycolic acid and the like can be mentioned, and as polybasic acid anhydrides, these anhydrides can be mentioned. These compounds may be used alone or in combination of two or more.

  In the present invention, the above polybasic acid-modified unsaturated monocarboxylic oxidized epoxy resin can also be used as a carboxyl group-containing photosensitive resin, but if necessary, the carboxyl of the above polybasic acid modified unsaturated monocarboxylic oxidized epoxy resin By reacting a glycidyl compound having one or more radically polymerizable unsaturated groups and an epoxy group to a group, a radically polymerizable unsaturated group is further introduced to further improve the photosensitivity. It may be a resin.

  In this carboxyl group-containing photosensitive resin having improved photosensitivity, the radically polymerizable unsaturated group is bonded to the side chain of the polybasic acid-modified unsaturated monocarboxylic oxidized epoxy resin skeleton by the reaction of the glycidyl compound. And photopolymerization reactivity is high, and can have excellent photosensitivity. Examples of the compound having one or more radically polymerizable unsaturated groups and an epoxy group include glycidyl acrylate, glycidyl methacrylate, allyl glycidyl ether, pentaerythritol triacrylate monoglycidyl ether, pentaerythritol trimethacrylate monoglycidyl ether, etc. It can be mentioned. In addition, you may have multiple glycidyl groups in 1 molecule. The compounds having one or more radically polymerizable unsaturated groups and epoxy groups may be used alone or in combination of two or more.

  The acid value of the carboxyl group-containing photosensitive resin is not particularly limited, but the lower limit thereof is preferably 30 mg KOH / g, particularly preferably 40 mg KOH / g, from the viewpoint of reliable alkali development. On the other hand, the upper limit value of the acid value is preferably 200 mg KOH / g from the viewpoint of the dissolution prevention of the exposed part by the alkaline developer, and particularly preferably 150 mg KOH / g from the viewpoint of the moisture resistance of the cured product and the deterioration prevention of the electrical characteristics.

  Further, the mass average molecular weight of the carboxyl group-containing photosensitive resin is not particularly limited, but the lower limit thereof is preferably 3,000, and particularly preferably 5,000, from the viewpoint of the toughness of the cured product and the contact dryness. On the other hand, the upper limit value of the mass average molecular weight is preferably 200,000, particularly preferably 50,000, from the viewpoint of smooth alkali developability.

(B) Block copolymer In the photosensitive resin composition of the present invention, as the (B) block copolymer, (b1) a carboxyl group-containing triblock copolymer and (b2) a triblock copolymer having no carboxyl group By blending the united body and the (b3) diblock copolymer, a cured product excellent in thermal shock resistance and solder heat resistance can be obtained.

(B1) Carboxyl group-containing triblock copolymer Examples of the carboxyl group-containing triblock copolymer include block copolymers of the [a ¹ ]-[b ¹ ]-[a ² ] structure. The polymer block of [a ¹ ] has a glass transition temperature higher than that of [b ¹ ], and thus has a relatively hard block structure. The glass transition temperature of [a ¹ ] is preferably 100 ° C. or more, particularly preferably 120 ° C. or more, from the viewpoint of thermal shock resistance and solder heat resistance. The polymer block [a ^1], for example, a copolymer of a copolymer component having an alkyl (meth) acrylate and a carboxyl group (alkyl (meth) not acrylate). Therefore, the polymer block of [a ¹ ] is a polymer block having a carboxyl group. Examples of alkyl (meth) acrylates which are monomer raw materials include methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate and hydroxyethyl (meth) acrylate. It can be mentioned. As a copolymerization component which has a carboxyl group which is a monomer raw material, (meth) acrylic acid etc. can be mentioned, for example. The proportion of the polymer alkyl in the block (meth) acrylate ^{[a 1]} is not particularly limited, is preferably 50 to 90 wt%. The glass transition temperature can be measured by differential scanning calorimetry (DSC method).

Similarly to the polymer block of [a ¹ ], the polymer block of [a ² ] has a glass transition temperature higher than that of [b ¹ ], and thus has a relatively hard block structure. The glass transition temperature of ^{[a 2],} as with ^{[a 1],} preferably 100 ° C. or higher from the viewpoint of thermal shock resistance and solder heat resistance, particularly preferably at least 120 ° C.. As the polymer block of [a ² ], for example, as in the polymer block of [a ¹ ], a copolymer of an alkyl (meth) acrylate and a copolymer component having a carboxyl group (not an alkyl (meth) acrylate) It can be mentioned coalescence. Examples of the alkyl (meth) acrylate which is a monomer raw material include methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate as well as the polymer block of [a ¹ ]. ) Acrylate and hydroxyethyl (meth) acrylate etc. can be mentioned. Examples of the copolymerizable component having a carboxyl group is a monomer raw material, for example, as in the polymer block [a ^1], may be mentioned (meth) acrylic acid. The proportion of the polymer alkyl in the block (meth) acrylate ^{[a 2]} is not particularly limited, is preferably 50 to 90 wt%.

The polymer block of [b ¹ ] has a glass transition temperature lower than the polymer block of [a ¹ ] and the polymer block of [a ² ], and thus has a relatively soft block structure. The glass transition temperature of [b ¹ ] is preferably −10 ° C. or less, particularly preferably −30 ° C. or less, from the viewpoint of preventing generation of cracks even when receiving thermal shock by providing flexibility to the cured product. Examples of the polymer block of [b ¹ ] include polymers of alkyl (meth) acrylates. Therefore, the polymer block of [b ¹ ] is a polymer block having no carboxyl group. Examples of the alkyl (meth) acrylate which is a monomer raw material include ethyl (meth) acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate and hydroxyethyl (meth) acrylate.

The content of the polymer block of [b ¹ ] in the carboxyl group-containing triblock copolymer is not particularly limited. For example, from the viewpoint of improving the hardness of the cured product, solder heat resistance and thermal shock resistance in a well-balanced manner 55 mass% is preferable, and 35 to 50 mass% is particularly preferable. Further, the mass average molecular weight of the carboxyl group-containing triblock copolymer is not particularly limited. For example, the lower limit thereof is preferably 10000, and particularly preferably 20000. On the other hand, the upper limit thereof is preferably 200,000, and particularly preferably 150,000.

  The content of the (b1) carboxyl group-containing triblock copolymer is not particularly limited, but the lower limit thereof improves the thermal shock resistance and the solder heat resistance in a well-balanced manner with respect to 100 parts by mass of the carboxyl group-containing photosensitive resin. The content is preferably 2.0 parts by mass from the viewpoint of making it possible, more preferably 4.0 parts by mass, and particularly preferably 6.0 parts by mass from the viewpoint of further improving solder heat resistance. On the other hand, the upper limit thereof is preferably 30 parts by mass from the viewpoint of reliably preventing a decrease in solder heat resistance with respect to 100 parts by mass of the carboxyl group-containing photosensitive resin, and 15 parts by mass from the point of further improving the coating film appearance. A part is more preferable, and 13 parts by mass is particularly preferable in terms of further improving the thermal shock resistance and the solder heat resistance in a well-balanced manner.

(B2) Triblock Copolymer Having No Carboxyl Group For a triblock copolymer not having a carboxyl group, for example, a block copolymer having an [a ³ ]-[b ² ]-[a ⁴ ] structure is given. be able to. The polymer block of [a ³ ] has a glass transition temperature higher than that of [b ² ], and thus has a relatively hard block structure. The glass transition temperature of [a ³ ] is preferably 60 ° C. or higher, particularly preferably 90 ° C. or higher, from the viewpoints of thermal shock resistance and solder heat resistance. As the polymer block of [a ³ ], for example, a polymer of an alkyl (meth) acrylate, a copolymer of an alkyl (meth) acrylate and another copolymer component not having a carboxyl group which is not an alkyl (meth) acrylate Coalescence etc. can be mentioned. Examples of alkyl (meth) acrylates which are monomer raw materials include methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate and hydroxyethyl (meth) acrylate. It can be mentioned. As another copolymerization component which does not have a carboxyl group which is a monomer raw material, dimethyl (meth) acrylamide etc. can be mentioned, for example.

The polymer block of [a ⁴ ], like the polymer block of [a ³ ], has a glass transition temperature higher than that of the polymer block of [b ² ], and thus has a relatively hard block structure. The glass transition temperature of [a ^4], like [a ^3], preferably 60 ° C. or higher from the viewpoint of thermal shock resistance and solder heat resistance, particularly preferably at least 90 ° C.. As the polymer block of [a ⁴ ], for example, as with the polymer block of [a ³ ], a polymer of alkyl (meth) acrylate, and a carboxyl group other than alkyl (meth) acrylate and alkyl (meth) acrylate The copolymer etc. with the other copolymerization component which does not have can be mentioned. Examples of alkyl (meth) acrylates which are monomer raw materials include methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate and hydroxyethyl (meth) acrylate. It can be mentioned. As another copolymerization component which does not have a carboxyl group which is a monomer raw material, dimethyl (meth) acrylamide etc. can be mentioned, for example. Polymer block ratio of an alkyl (meth) acrylate in the solution of ^{[a 4]} is not particularly limited, is preferably 50 to 90 wt%.

  The proportion of the other copolymer component which does not have a carboxyl group in the triblock copolymer which does not contain a carboxyl group (raw material conversion) is not particularly limited, but 5 to 20 mass% is preferable, and 10 to 15 mass is preferable. Particularly preferred.

The polymer block of [b ² ] has a glass transition temperature lower than the polymer block of [a ³ ] and the polymer block of [a ⁴ ], and thus has a relatively soft block structure. The glass transition temperature of [b ² ] is preferably −10 ° C. or less, particularly preferably −30 ° C. or less, from the viewpoint of preventing generation of cracks even when receiving thermal shock by providing flexibility to the cured product. Examples of the polymer block of [b ² ] include poly n-butyl (meth) acrylate, polybutadiene, polyisoprene and the like.

The content of [b ² ] in the triblock copolymer not containing a carboxyl group is not particularly limited. For example, from the viewpoint of improving the hardness of the cured product, solder heat resistance and thermal shock resistance in a well-balanced manner % Is preferable, and 40 to 55% by mass is particularly preferable. Moreover, the mass average molecular weight of the triblock copolymer which does not contain a carboxyl group is not specifically limited, For example, 5000 are preferable and, as for the lower limit, 10000 is especially preferable. On the other hand, the upper limit thereof is preferably 100,000, and particularly preferably 50,000.

  The content of the triblock copolymer not containing a carboxyl group (b2) is not particularly limited, but the lower limit thereof balances thermal shock resistance and solder heat resistance with respect to 100 parts by mass of a carboxyl group-containing photosensitive resin. It is preferably 2.0 parts by mass, particularly preferably 3.0 parts by mass, in order to improve the properties. On the other hand, the upper limit thereof is preferably 20 parts by mass, particularly preferably 10 parts by mass, from the viewpoint of reliably preventing a decrease in solder heat resistance with respect to 100 parts by mass of the carboxyl group-containing photosensitive resin.

(B3) Diblock copolymer Examples of the diblock copolymer include block copolymers of the [a ⁵ ]-[b ³ ] structure. Here, the polymer block of [a ⁵ ] has a glass transition temperature higher than that of [b ³ ], and thus has a relatively hard block structure. The glass transition temperature of [a ⁵ ] is preferably 60 ° C. or higher, particularly preferably 90 ° C. or higher, from the viewpoint of hardness of the cured product and solder heat resistance. Examples of the polymer block of [a ⁵ ] include methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate and hydroxyethyl (meth) acrylate. be able to.

The polymer block of [b ³ ] has a glass transition temperature lower than that of [a ⁵ ], and thus has a relatively soft block structure. The glass transition temperature of [b ³ ] is preferably −10 ° C. or less, particularly preferably −30 ° C. or less, from the viewpoint of preventing the occurrence of cracks even when receiving thermal shock by providing flexibility to the cured product. Examples of the polymer block of [b ³ ] include poly n-butyl (meth) acrylate, polybutadiene, polyisoprene and the like.

The content of [b ³ ] in the diblock copolymer is not particularly limited, and is preferably 20 to 70% by mass from the viewpoint of improving the hardness of the cured product, solder heat resistance and thermal shock resistance in a more balanced manner, for example 40 to 65% by mass is particularly preferred. Further, the mass average molecular weight of the diblock copolymer is not particularly limited. For example, the lower limit thereof is preferably 10000, and particularly preferably 20000. On the other hand, the upper limit thereof is preferably 200,000, and particularly preferably 100,000.

  The content of the diblock copolymer (b3) is not particularly limited, but the lower limit thereof is from the point of improving the thermal shock resistance and the solder heat resistance in a well-balanced manner with respect to 100 parts by mass of the carboxyl group-containing photosensitive resin. 2.0 parts by mass is preferable, and 3.0 parts by mass is particularly preferable. On the other hand, the upper limit thereof is preferably 20 parts by mass, particularly preferably 10 parts by mass, from the viewpoint of reliably preventing a decrease in solder heat resistance with respect to 100 parts by mass of the carboxyl group-containing photosensitive resin.

  The ratio of the total of (b2) carboxyl group-free triblock copolymer and (b3) diblock copolymer to (b1) carboxyl group-containing triblock copolymer is not particularly limited, but (b2) carboxyl The total amount of the triblock copolymer containing no groups and the (b3) diblock copolymer is a good balance between solder heat resistance and thermal shock resistance with respect to 100 parts by mass of the (b1) carboxyl group-containing triblock copolymer. 30 mass parts or more are preferable from the point to improve, 50 mass parts or more are more preferable, and 80 mass parts or more are especially preferable from the point which further improves solder heat resistance. On the other hand, the total of the (b2) triblock copolymer not containing a carboxyl group and the (b3) diblock copolymer is the solder heat resistance with respect to 100 parts by mass of the (b1) carboxyl group-containing triblock copolymer. And 500 parts by mass or less is preferable from the viewpoint of improving the thermal shock resistance in a well-balanced manner, 400 parts by mass or less is more preferable, and 160 parts by mass or less is particularly preferable from the point of further improving solder heat resistance.

  The content of the block copolymer (B) is not particularly limited, but the lower limit thereof is 10 from the point of improving the solder heat resistance and the thermal shock resistance in a well-balanced manner with respect to 100 parts by mass of the carboxyl group-containing photosensitive resin. Parts by weight are preferred, and 12 parts by weight are particularly preferred. On the other hand, the upper limit thereof is preferably 30 parts by mass, particularly preferably 20 parts by mass, from the viewpoint of improving the solder heat resistance and the thermal shock resistance in a well-balanced manner with respect to 100 parts by mass of the carboxyl group-containing photosensitive resin.

(C) Photopolymerization initiator The photopolymerization initiator is not particularly limited as long as it is generally used, and, for example, ethanone, 1- [9-ethyl-6- (2-methylbenzoyl) -9H- Carbazol-3-yl] -1- (0-acetyloxime), 2,4,6-trimethyl benzoyl diphenyl phosphine oxide, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin n-butyl ether, benzoin isobutyl Ether, acetophenone, dimethylaminoacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2,2-diethoxy-2-phenylacetophenone, 2-methyl-4 '-(methylthio) -2-morpholinopropiophenone, 2- Benzyl-2- (N, N-dimethyl) Mino) -1- (4-morpholinophenyl) butan-1-one, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1-hydroxycyclohexyl phenyl ketone, 4- (2-hydroxyethoxy) Phenyl-2- (hydroxy-2-propyl) ketone, benzophenone, p-phenyl benzophenone, 4,4'-diethylamino benzophenone, dichloro benzophenone, 2-methyl anthraquinone, 2-ethyl anthraquinone, 2-tertiary butyl anthraquinone, 2 -Aminoanthraquinone, 2-methylthioxanthone, 2-ethylthioxanthone, 2-chlorothioxanthone, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, benzyl dimethyl ketal, acetophenone dimethyl ketal, P-dimethylaminobenzoic acid ethyl ester and the like can be mentioned. These may be used alone or in combination of two or more.

  Although content of a photoinitiator is not specifically limited, 5-30 mass parts is preferable with respect to 100 mass parts of carboxyl group-containing photosensitive resin, and 7-20 mass parts is especially preferable.

(D) Reactive Diluent The reactive diluent is, for example, a photopolymerizable monomer, and is a compound having at least one, preferably at least two polymerizable double bonds per molecule per molecule. The reactive diluent is used to sufficiently cure the photosensitive resin composition to obtain a cured product having acid resistance, heat resistance, alkali resistance and the like.

  The reactive diluent is not particularly limited as long as it is the above-mentioned compound, and, for example, 2-hydroxyethyl methacrylate, phenoxyethyl methacrylate, diethylene glycol monomethacrylate, 2-hydroxy-3-phenoxypropyl acrylate, 1,4- Butanediol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, neopentyl glycol adipate di (meth) acrylate, hydroxypivalate neo Pentyl glycol di (meth) acrylate, dicyclopentanyl di (meth) acrylate, caprolactone modified dicyclopentenyl di (meth) acrylate, ethylene oxide modified phosphoric acid di (meth) acrylate , Allylated cyclohexyl di (meth) acrylate, isocyanurate di (meth) acrylate, trimethylolpropane tri (meth) acrylate, ditrimethylolpropane tetra (meth) acrylate, dipentaerythritol tri (meth) acrylate, dipentaerythritol tri (Meth) acrylate, pentaerythritol tri (meth) acrylate, propylene oxide modified trimethylolpropane tri (meth) acrylate, tris (acryloxyethyl) isocyanurate, propionic acid modified dipentaerythritol penta (meth) acrylate, dipentaerythritol hexamer Caprolactone modified dipentanes such as (meth) acrylate, caprolactone modified dipentaerythritol hexa (meth) acrylate, etc. (Meth) acrylates of Risuritoru include urethane (meth) acrylate and the like. These may be used alone or in combination of two or more.

  Among these, caprolactone-modified dipentaerythritol (meth) acrylates such as caprolactone-modified dipentaerythritol hexa (meth) acrylate are preferable in that they also contribute to more reliably improving thermal shock resistance and solder heat resistance.

  The content of the reactive diluent is not particularly limited, and for example, 2.0 to 300 parts by mass is preferable, and 10 to 100 parts by mass is particularly preferable with respect to 100 parts by mass of the carboxyl group-containing photosensitive resin.

(E) Epoxy Compound The epoxy compound is for increasing the crosslink density of the cured coating film to obtain a cured coating film of sufficient strength. For example, an epoxy resin is added. Examples of the epoxy resin include biphenyl type epoxy resin, bisphenol A type epoxy resin, novolac type epoxy resin (phenol novolac type epoxy resin, o-cresol novolac type epoxy resin, p-tert-butylphenol novolac type, etc.), bisphenol F and the like Bisphenol F type or bisphenol S type epoxy resin obtained by reacting epichlorohydrin with bisphenol S, cycloaliphatic epoxy resin having cyclohexene oxide group, tricyclodecane oxide group, cyclopentene oxide group, etc., tris (2,3-) Triglycidyl isocyanurate having a triazine ring such as epoxypropyl) isocyanurate, triglycidyl tris (2-hydroxyethyl) isocyanurate, dicyclopentadi Resin type epoxy resin, adamantane type epoxy resin, glycidyl ester type epoxy resin (eg, diglycidyl phthalic acid ester, diglycidyl ester of hexahydrophthalic acid, diglycidyl ester of isophthalic acid, diglycidyl ester of dimer acid, etc.) it can. These compounds may be used alone or in combination of two or more.

  Among these, glycidyl ester type epoxy resins are preferable in that they also contribute to more surely improving the thermal shock resistance without impairing the excellent solder heat resistance.

  The content of the epoxy compound is not particularly limited, but it is preferably 10 to 70 parts by mass, and 20 to 60 parts by mass with respect to 100 parts by mass of the carboxyl group-containing photosensitive resin from the viewpoint of obtaining a coating film having sufficient strength after curing. Parts are particularly preferred.

  In the photosensitive resin composition of the present invention, in addition to the components (A) to (E) described above, various components such as fillers, pigments, various additives, solvents and the like may be contained as needed. be able to.

  The filler is for increasing the physical strength of the coating film of the photosensitive resin composition, and examples thereof include talc, barium sulfate, hydrophobic silica, alumina, aluminum hydroxide and mica. Although content of a filler is not specifically limited, For example, 10-70 mass parts is preferable with respect to 100 mass parts of carboxyl group-containing photosensitive resin, and 20-60 mass parts is especially preferable.

  The pigment is not particularly limited, and, for example, titanium oxide which is a white colorant, and organic pigments such as phthalocyanine green such as phthalocyanine green and phthalocyanine blue as an colorant other than white, anthraquinone, and azo, carbon black Etc. can be mentioned.

  Various additives include, for example, antifoaming agents such as silicones, hydrocarbons, and acrylics, coupling agents such as silanes, titanates and aluminas, boron trifluoride-amine complex, dicyandiamide (DICY), Its derivatives, organic acid hydrazide, diaminomaleonitrile (DAMN) and its derivatives, guanamine and its derivatives, melamine and its derivatives, latent curing agents such as amine imides (AI) and polyamines, acetylacenate Zn, acetylacenate Cr, etc. Metal salts of acetylacetone, enamines, tin octylate, quaternary sulfonium salts, imidazoles such as triphenylphosphine and 2-mercaptobenzimidazole, imidazolium salts, thermosetting accelerators such as triethanolamine borate, and polycarboxylic acids A And the like can be mentioned thixotropic agent such as Ido.

  The solvent is for controlling the drying property of the photosensitive resin composition. Examples of solvents include ketones such as methyl ethyl ketone and cyclohexanone; aromatic hydrocarbons such as toluene, xylene and tetramethylbenzene; methyl cellosolve, ethyl cellosolve, butyl cellosolve, methyl carbitol, butyl carbitol, propylene glycol monomethyl ether, Glycol ethers such as diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, dipropylene glycol monoethyl ether, triethylene glycol monoethyl ether; ethyl acetate, butyl acetate, cellosolve acetate, diethylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, propylene glycol Monomethyl ether acetate and the above glyco Esters such as esters of ethers; ethanol, can be mentioned propanol, ethylene glycol, and alcohols such as propylene glycol.

  The method for producing the photosensitive resin composition of the present invention described above is not limited to a specific method, but, for example, it may be produced by mixing and dispersing the above-mentioned respective components in predetermined proportions with three rolls at room temperature. it can. Moreover, you may pre-mix with a stirrer before the said mixing dispersion | distribution as needed.

  Next, an example of how to use the photosensitive resin composition of the present invention will be described. Here, a method of applying the photosensitive resin composition of the present invention to a printed wiring board to form an insulating film such as a solder resist film will be described as an example.

  The printed wiring board is coated with the photosensitive resin composition of the present invention manufactured as described above at a desired thickness, for example, a thickness of 5 to 100 μm. As a means for coating, any known means can be used, and it is possible to select as appropriate. For example, screen printing, bar coater, spray coating, applicator, blade coater, knife coater, roll coater, gravure coater etc. It can be mentioned. After coating, if necessary, the photosensitive resin composition is preliminarily dried in a hot air oven or far-infrared oven or the like to volatilize the solvent from the photosensitive resin composition to make the surface of the coating film tack-free. The predrying temperature is preferably 60 to 80 ° C., and the predrying time is preferably 15 to 60 minutes. Thereafter, a negative film having a pattern in which portions other than the lands of the circuit pattern are made translucent is brought into close contact with the applied photosensitive resin composition, and ultraviolet light is applied from above. Then, the coating film is developed by removing the non-exposed area corresponding to the land with a dilute alkaline aqueous solution. For example, a spray method, a shower method or the like is used for the development method, and a 0.5 to 5% by mass sodium carbonate aqueous solution can be used as the dilute alkaline aqueous solution, for example. Then, an insulating film having a target pattern can be formed on the printed wiring board by performing post curing for 20 to 80 minutes with a hot air circulating dryer at 130 to 170 ° C. or the like.

  EXAMPLES Next, examples of the present invention will be described, but the present invention is not limited to these examples as long as the purpose of the present invention is not exceeded.

Examples 1 to 9 and Comparative Examples 1 to 4
Each component shown in the following Tables 1 and 2 is compounded in the mixing ratio shown in the following Tables 1 and 2, mixed and dispersed at room temperature using a three-roll, Examples 1 to 9 (shown in Table 1), Photosensitive resin compositions used in Comparative Examples 1 to 4 (shown in Table 2) were prepared. And the prepared photosensitive resin composition was coated as follows, and the test piece was produced. The numbers in Tables 1 and 2 below indicate parts by mass. Moreover, the blank in Tables 1 and 2 below means no blending.

  In addition, the detail about each component in Table 1, 2 is as follows.

(A) Carboxyl Group-Containing Photosensitive Resin · Lipoxy SP-4621: At least a part of the epoxy group of a cresol novolac epoxy resin is reacted with acrylic acid to obtain epoxy acrylate, and the generated hydroxyl group is reacted with a polybasic acid Acid-modified epoxy acrylate, which is a structure obtained by 65% solid content, Showa Denko KK.

(B1) Carboxyl group-containing triblock copolymer SM4032XM10: [a ¹ ]-[b ¹ ]-[a ² ]
(Wherein [a ¹ ] is a copolymer of methyl methacrylate and a carboxyl group-containing (meth) acrylic copolymer component (glass transition temperature 120 ° C. to 140 ° C.), [b ¹ ] is polybutyl acrylate (glass Transition temperature -54 ° C), [a ² ] is a copolymer of methyl methacrylate and a carboxyl group-containing (meth) acrylic copolymer component (glass transition temperature 120 ° C to 140 ° C), [a ¹ ] and [a ² ] Sum of the mass of / 2 [mass of [b ¹ ] = 3/2). Arkema company with a mass average molecular weight of 130000.

(B2) Triblock copolymer having no carboxyl group · Nanostrength M52N: [a ³ ]-[b ² ]-[a ⁴ ]
(Wherein [a ³ ] is polymethyl methacrylate (glass transition temperature 120 ° C. to 140 ° C.) obtained by copolymerizing N, N-dimethyl acrylamide, and [b ² ] is polybutyl acrylate (glass transition temperature -65 ° C.-- 45 ° C.), [a ⁴ ] is a polymethyl methacrylate copolymerized with N, N-dimethyl acrylamide (glass transition temperature 120 ° C. to 140 ° C.), the total mass of [a ³ ] and [a ⁴ ] / [b ^2] ] Mass = 1/1). A polymerization ratio of N, N-dimethyl acrylamide is 10 to 15% by mass (raw material conversion) with respect to the total mass of the triblock copolymer (raw material conversion), mass average molecular weight 15,000, Arkema.

(B3) Diblock copolymer · LA 1114: polymethyl methacrylate-polybutyl acrylate diblock copolymer, one end PMMA, content of butyl acrylate is 60% by mass or more, weight average molecular weight 80 000, acid value O mg KOH / g , Inc. Kuraray.

(C) Photopolymerization initiator Irgacure 369: Ciba Specialty Chemicals.
-SPEEDCURE TPO: Nihon Shiver Hegner.
-KAYACURE DETX: Nippon Kayaku Co., Ltd.

(D) Reactive Diluent KAYARAD DPCA-60: Nippon Kayaku Co., Ltd.
DPHA: Toagosei Co., Ltd.
(E) Epoxy compound jER 871, YX-4000HK: Mitsubishi Chemical Corporation.
EPICRON N-695: DIC Corporation.

Filler barium sulfate B-34: Sakai Chemical Industry Co., Ltd.
-FH 105: Fuji Talc Co., Ltd.
· AEROSIL # 2000: Nippon Aerosil Co., Ltd.
Pigment · first gen green: DIC.
Additives and melamine: Nissan Chemical Industries, Ltd.
DICY-7: Japan Epoxy Resins Co., Ltd.
・ Ange MB: Kawaguchi Chemical Industry Co., Ltd.
-BYK-405: Big Chemie.
Solvent · EDGAC: Sanyo Chemical Industries, Ltd.

Test piece production process board: Printed wiring board (glass epoxy board "FR-4", board thickness 1.6 mm, conductor (Cu foil) thickness 50 μm)
Substrate surface treatment: Buffing coating: Screen printing DRY film thickness: 20 to 25 μm
Pre-drying: 80 ° C., 20 minutes exposure: 300 mJ / cm ² (Oak "HMW-680 GW") on the photosensitive resin composition
Alkali development: 1% by mass Na ₂ CO ₃ , solution temperature 30 ° C., spray pressure 0.2 MPa, development time 60 seconds Post cure: 150 ° C., 60 minutes

The evaluation and measurement items are as follows.
(1) Thermal shock resistance 100 test pieces prepared in the above test piece preparation step are subjected to a thermal shock tester (Hitachi Appliances, Ltd., Hitachi Heat Shock Tester “ES-76 LMS”) at −65 ° C. A test of 1000 cycles was performed with one cycle of / 30 minutes to 125 ° C / 30 minutes. Then, the coating film of the printed wiring board was observed with a microscope (x 200), and the crack generation rate of the coating film was evaluated based on the following criteria. The observation position of the coating film was each corner of the coating film alkali-developed in a square shape (2.4 mm square) so as to surround the exposed Cu foil (2.0 mm square pad).
:: Crack incidence rate is 10% or less ○: Crack incidence rate is 11 to 30%
:: 31 to 50% crack occurrence rate
X: Crack incidence rate is 50% or more

(2) Soldering heat resistance The cured coating film of the test piece prepared in the above test piece preparing step is dipped in a solder bath at 260 ° C. for 30 seconds in accordance with the test method of JIS C-6481, and then with a cellophane adhesive tape The peeling test (peeling test) was made into 1 cycle, the coating-film state after repeating this 1-3 times was observed visually, and the following references | standards evaluated.
◎: No change in coating film observed even after 3 cycles
○: change in the coating is observed after 3 cycles, Δ: change in the coating after 2 cycles, ×: change in the coating in 1 cycle

(3) Coating film hardness About the coating film on Cu foil of the test piece produced at the said test piece production process, pencil hardness was evaluated in accordance with the test method of JISK-5600-5-4.

(4) Alkali developability The time required for developing (at 30 ° C., using 1% by mass sodium carbonate developer) at a spray pressure of 0.2 MPa the coating film after the preliminary drying in the test piece preparation step The time was taken as the breakpoint. The evaluation was performed in the following three stages.
○: Breakpoint less than 30 seconds :: Breakpoint greater than 30 seconds and less than 60 seconds ×: Breakpoint greater than 60 seconds

(5) Coating film appearance The coating film state of the test piece prepared in the test piece preparing step was visually observed and evaluated according to the following criteria.
○: no abnormality in the film Δ: some whitening in the film ×: the surface of the film is lost

  The evaluation results of Examples 1 to 9 are shown in Table 1 below, and the evaluation results of Comparative Examples 1 to 4 are shown in Table 2 below.

  As shown in Table 1 above, as the (B) block copolymer, (b1) a carboxyl group-containing triblock copolymer, (b2) a triblock copolymer not containing a carboxyl group, and (b3) a diblock In each of the examples containing a copolymer, a cured coating film excellent in thermal shock resistance and solder heat resistance could be obtained without impairing the coating film hardness, the alkali developability, and the coating film appearance. In particular, the total of the (b2) triblock copolymer not containing a carboxyl group and the (b3) diblock copolymer is at least 100 parts by mass with respect to 100 parts by mass of the (b1) carboxyl group-containing triblock copolymer. In Examples 1 and 2 in the range of not more than parts by mass, a cured coating film in which both the thermal shock resistance and the solder heat resistance were further improved could be obtained.

  From the comparison of Example 1 and Examples 7 and 9, when the dimer acid diglycidyl ester was blended as the epoxy compound, it also contributed to the improvement of the thermal shock resistance. From the comparison of Example 1 and Examples 8 and 9, when an acrylate of ε-caprolactone modified dipentaerythritol was blended as a reactive diluent, it also contributed to the improvement of the thermal shock resistance and the solder heat resistance.

  On the other hand, as shown in Table 2 above, solder heat resistance was not obtained in Comparative Example 1 in which the (b1) carboxyl group-containing triblock copolymer was not blended. Moreover, although the (b1) carboxyl group-containing triblock copolymer was blended, the thermal shock resistance was not obtained in Comparative Example 2 in which the (b3) diblock copolymer was not blended. In Comparative Example 3 in which (b1) a carboxyl group-containing triblock copolymer is blended but (b2) a carboxyl group-free triblock copolymer is not blended, the acceptable level of thermal shock resistance is Although obtained, solder heat resistance was not obtained. In Comparative Example 4 in which the block copolymer (B) was not blended, acceptable solder heat resistance was obtained, but thermal shock resistance was not obtained.

  The photosensitive resin composition of the present invention can obtain a cured product excellent in thermal shock resistance and solder heat resistance without deteriorating basic characteristics such as coating film hardness, alkali developability, and coating film appearance. For example, it is highly useful in the field of printed wiring boards.

Claims (7)

(A) a carboxyl group-containing photosensitive resin, (B) a block copolymer, (C) a photopolymerization initiator, (D) a reactive diluent, and (E) an epoxy compound,
The (B) block copolymer includes (b1) a carboxyl group-containing triblock copolymer, (b2) a carboxyl group-free triblock copolymer, and (b3) a diblock copolymer. The photosensitive resin composition characterized by the above-mentioned.   The photosensitivity according to claim 1, wherein the (b1) carboxyl group-containing triblock copolymer contains 4.0 parts by mass or more and 13 parts by mass or less with respect to 100 parts by mass of the (A) carboxyl group-containing photosensitive resin. Resin composition.   100 parts by mass of the (b1) carboxyl group-containing triblock copolymer, 30 parts by mass in total of the (b2) carboxyl group-free triblock copolymer and the (b3) diblock copolymer The photosensitive resin composition according to claim 1 or 2, which contains 400 parts by mass or less.   The said (B) block copolymer is 10 mass parts or more and 20 mass parts or less containing with respect to 100 mass parts of said (A) carboxyl group-containing photosensitive resin of any one of Claims 1 thru | or 3. Photosensitive resin composition.   The photosensitive resin composition according to any one of claims 1 to 4, wherein the (D) reactive diluent contains (meth) acrylate of ε-caprolactone modified dipentaerythritol.   The photosensitive resin composition according to any one of claims 1 to 5, wherein the (E) epoxy compound contains a glycidyl ester type epoxy resin.   The photosensitive resin composition of any one of Claims 1 thru | or 6 was apply | coated, The printed wiring board characterized by the above-mentioned.