CN120936949A - Photosensitive thermosetting resin compositions, dry films, cured products and electronic components - Google Patents

Abstract

This invention provides a photosensitive thermosetting resin composition capable of forming a solder resist film with excellent surface curability, heat resistance, and high reflectivity even with low exposure. The photosensitive thermosetting resin composition comprises a carboxyl-containing resin, a photopolymerization initiator, a white pigment, and a thermosetting resin. The photopolymerization initiator includes oxime ester-based photopolymerization initiators and titanium-based photopolymerization initiators, and the thermosetting resin includes an epoxy resin. The cured product of the photosensitive thermosetting resin composition exhibits a b ^* value of 2.0 or less in the L ^* a ^* b ^* color system and a reflectivity of 85% or more at a wavelength of 450 nm.

Description

Photosensitive thermosetting resin composition, dry film, cured product, and electronic component

Technical Field

The invention relates to a photosensitive thermosetting resin composition, a dry film, a cured product and an electronic component.

Background

A light emitting device in which a light emitting diode (hereinafter, may be abbreviated as LED) is mounted on a printed wiring board is known. In order to efficiently use light of an LED mounted on a printed wiring board, a white solder resist film having a high reflectance may be formed on the printed wiring board (for example, refer to japanese patent application laid-open No. 2008/050768, japanese patent application laid-open No. 2008-134621, japanese patent application laid-open No. 2011-017010, and international publication No. 2012/141124). In addition, JP-A2013-210443 proposes a photocurable and thermosetting resin composition containing a photopolymerization initiator having no phosphorus atom in the molecular structure.

Disclosure of Invention

Problems to be solved by the invention

An object of one embodiment of the present invention is to provide a photosensitive thermosetting resin composition capable of forming a solder resist film excellent in surface curability and heat resistance and having a high reflectance even at a low exposure.

Means for solving the problems

The present invention includes the following aspects.

[1] A photosensitive thermosetting resin composition comprising a carboxyl group-containing resin, a photopolymerization initiator, a white pigment, and a thermosetting resin, wherein,

The photopolymerization initiator comprises an oxime ester photopolymerization initiator and a titanocene photopolymerization initiator,

The thermosetting resin comprises an epoxy resin and,

The b ^* value in the L ^*a^*b^* color system of the cured product of the photosensitive thermosetting resin composition after thermosetting is 2.0 or less, and the reflectance at the wavelength of 450nm is 85% or more.

[2] The photosensitive thermosetting resin composition according to [1], wherein the content ratio of the oxime ester-based photopolymerization initiator to the titanocene-based photopolymerization initiator is in the range of 1:10 to 10:1 on a mass basis with respect to the photopolymerization initiator.

[3] A dry film comprising a resin layer obtained by applying the photosensitive thermosetting resin composition according to [1] or [2] to a first film and drying the same.

[4] A cured product obtained by curing the photosensitive thermosetting resin composition according to [1] or [2 ].

[5] An electronic component, wherein the electronic component comprises the cured product of [4 ].

ADVANTAGEOUS EFFECTS OF INVENTION

According to one embodiment of the present invention, a photosensitive thermosetting resin composition capable of forming a solder resist film excellent in surface curability and heat resistance and having a high reflectance even at a low exposure level can be provided.

Detailed Description

In the present specification, the term "process" includes not only an independent process but also the term if the intended purpose of the process can be achieved even if it cannot be clearly distinguished from other processes. When a plurality of substances corresponding to the respective components are present in the composition, unless otherwise specified, the content of the respective components in the composition means the total amount of the plurality of substances present in the composition. The solid component is a substance from which volatile components (for example, organic solvents) are removed. Further, the upper limit and the lower limit of the numerical range described in the present specification can be arbitrarily selected as numerical values exemplified as the numerical range, respectively, and combined. Hereinafter, embodiments of the present invention will be described in detail. However, the embodiments shown below exemplify a photosensitive thermosetting resin composition, a dry film, a cured product, and an electronic component for embodying the technical concept of the present invention, and the present invention is not limited to the photosensitive thermosetting resin composition, the dry film, the cured product, and the electronic component shown below.

Photosensitive thermosetting resin composition

The photosensitive thermosetting resin composition comprises a carboxyl group-containing resin, a photopolymerization initiator, a white pigment, and a thermosetting resin. The photopolymerization initiator at least comprises an oxime ester photopolymerization initiator and a titanocene photopolymerization initiator. The thermosetting resin contains at least an epoxy resin. The b ^* value in the L ^*a^*b^* color system of the cured product of the photosensitive thermosetting resin composition after heat curing is 2.0 or less, and the reflectance at the wavelength of 450nm is 85% or more.

The photosensitive thermosetting resin composition can form a cured product having excellent surface curability and heat resistance and high reflectance even at a low exposure amount by incorporating a photopolymerization initiator having a specific structure as a photopolymerization initiator. In addition, discoloration of the cured product due to heat, light, or the like can be suppressed. Further, a latent image can be formed with high sensitivity and excellent resolution. This is thought to be caused, for example, by the synergistic effect of the oxime ester-based photopolymerization initiator and the titanocene-based photopolymerization initiator. The low exposure in the present invention is specifically 600mJ/cm ² or less.

Carboxyl group-containing resin

The carboxyl group-containing resin may be any resin having a carboxyl group in the molecule, and may or may not have a photosensitive functional group in the molecule. The photosensitive thermosetting resin composition contains a carboxyl group-containing resin, so that the photo-cured product of the photosensitive thermosetting resin composition obtained by irradiation of active energy rays can be provided with alkali developability. The carboxyl group-containing resin preferably has an ethylenically unsaturated double bond as a photosensitive functional group in a molecule from the viewpoints of photocurability, development resistance, and the like. The ethylenically unsaturated double bond in the molecule may be derived from acrylic acid or methacrylic acid or derivatives thereof. The photosensitive thermosetting resin composition may contain one kind of carboxyl group-containing resin alone or two or more kinds of carboxyl group-containing resins in combination. In the case where the photosensitive thermosetting resin composition contains only a carboxyl group-containing resin having no ethylenically unsaturated double bond as the carboxyl group-containing resin, the photosensitive thermosetting resin composition can be made photocurable by using a photopolymerizable monomer as a compound having a plurality of ethylenically unsaturated groups in the molecule as described later. Specific examples of the carboxyl group-containing resin include the following compounds (which may be any of oligomers and polymers). In the following, the term "(meth) acrylate" refers to a term collectively used for acrylate, methacrylate, and a mixture thereof, and other similar expressions are also similar.

(1) Carboxyl group-containing resins obtained by copolymerizing unsaturated carboxylic acids such as (meth) acrylic acid with unsaturated group-containing compounds such as styrene, α -methylstyrene, lower alkyl (meth) acrylate, isobutylene and the like.

(2) Carboxyl group-containing urethane resins produced by the polyaddition reaction of a diisocyanate such as aliphatic diisocyanate, branched aliphatic diisocyanate, alicyclic diisocyanate or aromatic diisocyanate with a carboxyl group-containing diol compound such as dimethylolpropionic acid or dimethylolbutyric acid, a polycarbonate polyol, a polyether polyol, a polyester polyol, a polyolefin polyol, an acrylic polyol, a bisphenol a-based alkylene oxide adduct glycol, a compound having a phenolic hydroxyl group and an alcoholic hydroxyl group, or the like.

(3) A carboxyl group-containing photosensitive urethane resin produced by the polyaddition reaction of a diisocyanate with a reaction product of a difunctional epoxy resin such as a bisphenol a type epoxy resin, a hydrogenated bisphenol a type epoxy resin, a bisphenol F type epoxy resin, a bisphenol S type epoxy resin, a bisxylenol type epoxy resin, a bisphenol type epoxy resin, and a monocarboxylic acid compound having an ethylenically unsaturated double bond such as (meth) acrylic acid, and a carboxyl group-containing diol compound.

(4) In the synthesis of the resin (2) or (3), a compound having one hydroxyl group and one or more (meth) acryloyl groups in the molecule, such as hydroxyalkyl (meth) acrylate, is added to the resin, and the carboxyl group-containing photosensitive urethane resin obtained by terminal (meth) acryloyl group is obtained.

(5) A carboxyl group-containing photosensitive urethane resin obtained by terminal (meth) acrylation of a compound having one isocyanate group and one or more (meth) acryloyl groups in the molecule, such as an equimolar reactant of isophorone diisocyanate and pentaerythritol triacrylate, is added to the synthesis of the resin of (2) or (3).

(6) A carboxyl group-containing photosensitive resin obtained by reacting a difunctional or more polyfunctional (solid) epoxy resin with (meth) acrylic acid and adding a dibasic acid anhydride to a hydroxyl group present in a side chain.

(7) A carboxyl group-containing photosensitive resin is obtained by reacting a (meth) acrylic acid with a polyfunctional epoxy resin obtained by epoxidizing the hydroxyl groups of a difunctional (solid) epoxy resin with epichlorohydrin, and adding a dibasic acid anhydride to the hydroxyl groups thus formed.

(8) A carboxyl group-containing polyester resin obtained by reacting a difunctional oxetane resin with a dicarboxylic acid such as adipic acid, phthalic acid or hexahydrophthalic acid, and adding a dibasic acid anhydride such as phthalic anhydride, tetrahydrophthalic anhydride or hexahydrophthalic anhydride to the primary hydroxyl group formed.

(9) A carboxyl group-containing photosensitive resin is obtained by reacting an epoxy compound having a plurality of epoxy groups in one molecule with a compound having at least one alcoholic hydroxyl group and one phenolic hydroxyl group in one molecule such as p-hydroxyphenylethanol and a monocarboxylic acid having an unsaturated group such as (meth) acrylic acid, and reacting the alcoholic hydroxyl group of the resultant reaction product with a polybasic acid anhydride such as maleic anhydride, tetrahydrophthalic anhydride, trimellitic anhydride, pyromellitic anhydride, adipic acid, etc.

(10) A carboxyl group-containing photosensitive resin is obtained by reacting a compound having a plurality of phenolic hydroxyl groups in one molecule with an alkylene oxide such as ethylene oxide or propylene oxide, reacting the resultant with a monocarboxylic acid containing an unsaturated group, and reacting the resultant with a polybasic acid anhydride.

(11) A carboxyl group-containing photosensitive resin is obtained by reacting a compound having a plurality of phenolic hydroxyl groups in one molecule with a cyclic carbonate compound such as ethylene carbonate or propylene carbonate, reacting the resultant with an unsaturated group-containing monocarboxylic acid, and reacting the resultant with a polybasic acid anhydride.

(12) The carboxyl group-containing photosensitive resin is obtained by further adding a compound having one epoxy group and one or more (meth) acryl groups in one molecule to the resins of the above (1) to (11).

Among them, from the viewpoint of suppressing warpage of a cured product, heat resistance, reflectance, and the like, it is preferable that the carboxyl group-containing resin is at least one of a carboxyl group-containing photosensitive urethane resin produced by addition polymerization of a diisocyanate such as an aliphatic diisocyanate, a branched aliphatic diisocyanate, an alicyclic diisocyanate, or an aromatic diisocyanate, and a carboxyl group-containing diol compound such as dimethylolpropionic acid or dimethylolbutyric acid, and a dihydroxy compound such as a polycarbonate polyol, a polyether polyol, a polyester polyol, a polyolefin polyol, an acrylic polyol, a bisphenol a-based alkylene oxide adduct glycol, a compound having a phenolic hydroxyl group and an alcoholic hydroxyl group, and a compound having a terminal (meth) acryloyl group, such as a hydroxyalkyl (meth) acrylate, added in the synthesis of the urethane resin. More preferably, the carboxyl group-containing resin is a carboxyl group-containing urethane resin produced by the addition polymerization reaction of an aliphatic diisocyanate such as an aliphatic diisocyanate, a branched aliphatic diisocyanate, or an alicyclic diisocyanate with a carboxyl group-containing diol compound and a dihydroxy compound such as a polycarbonate polyol, a polyether polyol, a polyester polyol, a polyolefin polyol, or an acrylic polyol, and may contain at least one of carboxyl group-containing photosensitive urethane resins obtained by adding a hydroxyalkyl (meth) acrylate to the synthesis of the urethane resin and subjecting the resultant mixture to terminal (meth) acryloyl groups.

In addition, from the viewpoints of heat resistance and reflectance of the cured product, it is preferable that the carboxyl group-containing resin contains at least one of a carboxyl group-containing photosensitive resin obtained by reacting a reaction product obtained by reacting a compound having a plurality of phenolic hydroxyl groups in one molecule with an alkylene oxide such as ethylene oxide or propylene oxide with a monocarboxylic acid containing an unsaturated group and reacting the obtained reaction product with a polybasic acid anhydride.

The acid value of the carboxyl group-containing resin may be, for example, 10 to 150mgKOH/g, preferably 30 to 120 mgKOH/g. The carboxyl group-containing resin has an acid value of 10mgKOH/g or more, and the photosensitive resin composition has good alkali developability. In addition, a good resist pattern can be easily drawn by setting the acid value to 150mgKOH/g or less. The acid value of the carboxyl group-containing resin was measured in accordance with JIS K0070:1992.

The weight average molecular weight of the carboxyl group-containing resin may vary depending on the resin skeleton, and is usually 2000 to 150000, preferably 5000 to 100000. The weight average molecular weight of 2000 or more can improve the surface drying performance, resolution, and the like. In addition, when the weight average molecular weight is 150000 or less, the developability, storage stability, and the like of the photosensitive resin composition can be improved. Here, the weight average molecular weight is a value in terms of polystyrene measured by gel permeation chromatography.

The content of the carboxyl group-containing resin in the photosensitive thermosetting resin composition is, for example, 5 mass% or more and 40 mass% or less, preferably 10 mass% or more and 35 mass% or less, in terms of solid content. The coating film strength can be improved by the content of the carboxyl group-containing resin being 5 mass% or more. Further, the carboxyl group-containing resin content of 40 mass% or less makes the photosensitive resin composition suitable in tackiness and improves processability.

Photosensitive compound

The photosensitive thermosetting resin composition may further contain at least one of photosensitive compounds having no carboxyl group. Examples of the photosensitive compound include a compound having an ethylenically unsaturated bond. The photosensitive compound may be a compound having a plurality of ethylenically unsaturated bonds.

Specific examples of the compound having an ethylenically unsaturated bond include the following compounds. Examples thereof include hydroxyalkyl (meth) acrylates such as 2-hydroxyethyl (meth) acrylate and 2-hydroxypropyl (meth) acrylate, acrylamides such as N, N-dimethyl (meth) acrylamide, N-hydroxymethyl (meth) acrylamide and N, N-dimethylaminopropyl (meth) acrylamide, aminoalkyl (meth) acrylates such as N, N-dimethylaminoethyl (meth) acrylate and N, N-dimethylaminopropyl (meth) acrylate, di (meth) acrylates derived from alkylene glycols such as ethylene glycol, polyethylene glycol, propylene glycol and polypropylene glycol, polyhydric alcohols such as hexanediol, trimethylolpropane, pentaerythritol, dipentaerythritol and trihydroxyethyl isocyanurate, polyhydric (meth) acrylates such as an ethylene oxide adduct, a propylene oxide adduct and epsilon-caprolactone adduct of these, aromatic group-containing polyhydric (meth) acrylates such as ethylene oxide adduct and propylene oxide adduct of bisphenol a, bisphenol F and these phenols, polyhydric (meth) acrylates such as glycidyl ethers, triglycidyl isocyanurate and triglycidyl isocyanurate. Further, the present invention is not limited to the above, and examples thereof include (meth) acrylates and melamine (meth) acrylates obtained by directly (meth) acrylating a polyol such as a polyether polyol, a polycarbonate diol, a hydroxyl-terminated polybutadiene, or a polyester polyol, or by urethane (meth) acrylating a diisocyanate compound.

Further, examples of the epoxy (meth) acrylate resin include epoxy (meth) acrylate resins obtained by reacting a polyfunctional epoxy resin such as cresol novolac type epoxy resin with (meth) acrylic acid, and epoxy urethane (meth) acrylate compounds obtained by further reacting hydroxyl groups of the epoxy (meth) acrylate resins with hydroxyl acrylates such as pentaerythritol tri (meth) acrylate and half-urethane compounds of diisocyanates such as isophorone diisocyanate. The epoxy (meth) acrylate resin can improve the photocurability without reducing the touch dryness.

The photosensitive compound may contain at least aromatic group-containing poly (meth) acrylates derived from bisphenol a, bisphenol F, and ethylene oxide adducts or propylene oxide adducts of these phenols. The photosensitive resin may contain one kind of photosensitive compound alone or two or more kinds of photosensitive compounds in combination.

When the photosensitive thermosetting resin composition contains a photosensitive compound, the content of the photosensitive compound may be, for example, 5 parts by mass or more and 100 parts by mass or less, preferably 10 parts by mass or more and 80 parts by mass or less, in terms of solid content, per 100 parts by mass of the carboxyl group-containing resin. When the content is 5 parts by mass or more, the photocurability is improved, and the pattern formation property by alkali development after irradiation with active energy rays tends to be further improved. In addition, if the amount is 100 parts by mass or less, the solubility in an aqueous alkali solution after irradiation with active energy rays can be sufficiently obtained, and the strength of the formed coating film tends to be further improved.

Photopolymerization initiator

The photosensitive thermosetting resin composition contains at least an oxime ester photopolymerization initiator and a titanocene photopolymerization initiator as photopolymerization initiators.

Oxime ester photopolymerization initiator

The oxime ester-based photopolymerization initiator may be any photopolymerization initiator having an O-acyl oxime structure in the molecule, and may be, for example, a photopolymerization initiator having a partial structure represented by the following formula (I).

Wherein R ¹ represents a hydrogen atom, a phenyl group which may have a substituent, an alkyl group which may have a substituent and has 1 to 20 carbon atoms, a cycloalkyl group which has 5 to 8 carbon atoms, an alkanoyl group which has 2 to 20 carbon atoms, or a benzoyl group which may have a substituent. R ² represents a phenyl group which may have a substituent, an alkyl group having 1 to 20 carbon atoms which may have a substituent, a cycloalkyl group having 5 to 8 carbon atoms, an alkanoyl group having 2 to 20 carbon atoms, or a benzoyl group which may have a substituent. Examples of the substituent in the phenyl group represented by R ¹ or R ² include an alkyl group having 1 to 6 carbon atoms, a phenyl group, a halogen atom, and the like. The number of substituents in the phenyl group may be 1 to 5. The alkyl group represented by R ¹ or R ² may be linear or branched and may be substituted with one or more hydroxyl groups. In addition, at least one of methylene groups constituting the alkyl group may be substituted with an oxygen atom or a carbonyl group. Examples of the substituent in the benzoyl group represented by R ¹ or R ² include an alkyl group having 1 to 6 carbon atoms, a phenyl group, and the like. The number of substituents in the benzoyl group may be 1 to 5.

Examples of the compound having a partial structure represented by the formula (I) may include diaryl sulfide, 9H-carbazole, thioxanthen-9-one, fluorene, and derivatives thereof. The partial structure represented by the formula (I) may be bonded in place of the hydrogen atom of these compounds or may be bonded through a carbonyl group.

Specifically, examples of the oxime ester photopolymerization initiator including a partial structure represented by the formula (I) include compounds represented by the following formulas (I-1), (I-2) and (I-3).

In formula (I-1), R ¹¹ is as defined for R ¹ in formula (I), and R ¹² is as defined for R ² in formula (I). R ¹³ represents a hydrogen atom, a hydroxyl group, a carboxyl group, a hydroxyalkoxy group, a hydroxyalkoxycarbonyl group, or the like. The number of carbon atoms in the hydroxyalkoxyl group in R ¹³ may be 1 to 20.n represents 0 or 1.

In the formula (I-2), R ²¹ is the same as R ¹ in the formula (I), and R ²² and R ²⁴ each independently represent a phenyl group which may have a substituent, an alkyl group having 1 to 20 carbon atoms which may have a substituent, a cycloalkyl group having 5 to 8 carbon atoms, an alkanoyl group having 2 to 20 carbon atoms, or a benzoyl group which may have a substituent. Examples of the substituent in the phenyl group represented by R ²⁴ include an alkyl group having 1 to 18 carbon atoms, an organic group having an acetal bond, and the like. The organic group having an acetal bond may be, for example, (2, 2-dimethyl-1, 3-dioxolan-4-yl) methoxy. R ²³ represents a hydrogen atom, a halogen atom, an alkyl group having 1 to 12 carbon atoms, a cycloalkyl group having 5 to 12 carbon atoms containing a substituent, a phenyl group, a benzyl group, a benzoyl group, an alkanoyl group having 2 to 12 carbon atoms, an alkoxycarbonyl group having 2 to 12 carbon atoms, or a phenoxycarbonyl group. The alkyl group constituting the alkoxycarbonyl group represented by R ²³ may be substituted with at least one hydroxyl group when the number of carbon atoms is 2 or more, and at least one of the methylene groups constituting the alkyl group may be substituted with an oxygen atom.

In formula (I-3), R ³¹ is as defined for R ¹ in formula (I), and R ³² is as defined for R ² in formula (I). R ³³ represents a hydrogen atom, a halogen atom, an alkyl group having 1 to 12 carbon atoms, a cycloalkyl group having 5 to 12 carbon atoms containing a substituent, or the like.

As the oxime ester photopolymerization initiator containing a structural moiety represented by the formula (I), specifically, 1- [4- (phenylmercapto (sulfanyl)) phenyl ] -1, 2-octanedione 2- (O-benzoyl oxime), 1- {4- [4- (2-hydroxyethoxy) phenylmercapto ] phenyl } propane-1, 2-dione 2- (O-acetyl oxime), 2- (acetoxyiminomethyl) thioxanthen-9-one, 1- [ 9-ethyl-6- (2-methylbenzoyl) -9H-carbazol-3-yl ] ethanone 1- (O-acetyl oxime), 1- [ 9-ethyl-6- (2-methyl-4-tetrahydrofuranylmethoxybenzoyl) -9H-carbazol-3-yl ] ethanone 1- (O-acetyl oxime), 1- [ 9-ethyl-6- { 2-methyl-4- (2, 2-dimethyl-1, 3-dioxolanyl) methoxybenzoyl } -9H-carbazol-3-yl ] ethanone 1- (O-acetyl oxime) can be mentioned 1- [4- [3- [4- [ [2- (acetoxy) ethyl ] sulfonyl ] -2-methylbenzoyl ] -6- [1- [ (acetoxy) imino ] ethyl ] -9H-carbazole ] -9-yl ] phenyloctanone 1- (O-acetyloxime) and the like. These oxime ester photopolymerization initiators may be used singly or in combination of two or more.

As commercial products of oxime ester photopolymerization initiators, ADEKA ARKLS NCI-700, ADEKA ARKLS NCI-730, ADEKA ARKLS NCI-831, ADEKA ARKLS NCI-930, 1-4- [ [4- (2-hydroxyethoxy) phenyl ] thio ] phenyl ] -1, 2-propanedione 2- (O-acetoxime) (manufactured by Ai Dike Co., ltd. (ADEKA CORPORATION) above), DFI-020, DFI-091 (manufactured by Daito Chemix Co., ltd.), CGI-325, irgacure OXE01, irgacure OXE02, 1- [ 9-ethyl-6- (2-methylbenzoyl) -9H-carbazol-3-yl ] ethanone 1- (O-acetoxime), irgacure OXE03, irgacure OXE04 (manufactured by Basoff Japanese Co., ltd.) and the like can also be used.

The content of the oxime ester photopolymerization initiator in the photosensitive thermosetting resin composition may be, for example, 0.01 to 10 parts by mass, preferably 0.02 to 8 parts by mass, and more preferably 0.05 to 5 parts by mass, per 100 parts by mass of the carboxyl group-containing resin, in terms of solid content. When the content of the oxime ester-based photopolymerization initiator is 0.01 part by mass or more, sufficient photocuring can be achieved. In addition, if the amount is 10 parts by mass or less, the balance between surface curing and bottom curing tends to be good. In one embodiment, the content of the oxime ester-based photopolymerization initiator may be 3 parts by mass or less, 2 parts by mass or less, or 1 part by mass or less.

Titanium-dicyclopentadiene-based photopolymerization initiator

The titanocene-based photopolymerization initiator may be a compound represented by the following formula (II).

Wherein R ⁹ and R ¹⁰ each independently represent a halogen atom, an aryl group, a halogenated aryl group containing a heterocycle.

Examples of the titanocene-based photopolymerization initiator represented by the formula (II) include bis (cyclopentadienyl) -bis [2, 6-difluoro-3- (2- (1H-pyrrol-1-yl) ethyl) phenyl ] titanium, bis (cyclopentadienyl) -bis [2, 6-difluoro-3- (3- (1H-pyrrol-1-yl) propyl) phenyl ] titanium, bis (cyclopentadienyl) -bis [2, 6-difluoro-3- ((1H-pyrrol-1-yl) methyl) phenyl ] titanium, bis (methylcyclopentadienyl) -bis [2, 6-difluoro-3- ((1H-pyrrol-1-yl) methyl) phenyl ] titanium, bis (cyclopentadienyl) -bis [2, 6-difluoro-3- ((2, 5-dimethyl-1H-pyrrol-1-yl) methyl) phenyl ] titanium, Bis (cyclopentadienyl) -bis [2, 6-difluoro-3- ((2-isopropyl-5-methyl-1H-pyrrol-1, 6-yl) methyl) phenyl ] titanium, bis (cyclopentadienyl) -bis [2, 6-difluoro-3- ((2- (2-methoxyethyl) -5-methyl-1H-pyrrol-1-yl) methyl) phenyl ] titanium, bis (cyclopentadienyl) -bis [2, 6-difluoro-3- ((3-trimethylsilyl-2, 5-dimethyl-1H-pyrrol-1-yl) methyl) phenyl ] titanium, bis (cyclopentadienyl) -bis [2, 6-difluoro-3- ((2, 5-dimethyl-3- (bis (2-methoxyethyl) aminomethyl) -1H-pyrrol-1-yl) methyl) phenyl ] titanium, Bis (cyclopentadienyl) -bis [2, 6-difluoro-3- ((2, 5-bis (morpholinomethyl) -1H-pyrrol-1-yl) methyl) phenyl ] titanium, bis (cyclopentadienyl) -bis [2, 6-difluoro-3- ((2, 5-dimethyl-3- (1, 3-dioxolan-2-yl) -1H-pyrrol-1-yl) methyl) phenyl ] titanium, bis (cyclopentadienyl) -bis [2, 6-difluoro-4- ((2, 5-dimethyl-1H-pyrrol-1-yl) methyl) phenyl ] titanium, bis (cyclopentadienyl) -bis [2, 6-difluoro-3-methyl-4- (2- (1H-pyrrol-1-yl) ethyl) phenyl ] titanium, bis (cyclopentadienyl) -bis [2, 6-difluoro-3- ((2, 3,4, 5-tetramethyl-1H-pyrrol-1-yl) methyl) phenyl ] titanium, bis (cyclopentadienyl) -bis [2,3,5, 6-tetrafluoro-4- (3- (1H-pyrrol-1-yl) propyl) phenyl ] titanium, bis (cyclopentadienyl) -bis [2, 6-difluoro-3- (2- (1H-pyrrol-1-yl) propyl) phenyl ] titanium, bis (cyclopentadienyl) -bis [2, 6-difluoro-3- (1-methyl-2- (1H-pyrrol-1-yl) ethyl) phenyl ] titanium, bis (cyclopentadienyl) -bis [2, 6-difluoro-3- (3- (2-isoindol-2-yl) propyl) phenyl ] titanium, Bis (cyclopentadienyl) -bis [2, 6-difluoro-3- (2- (4, 5,6, 7-tetrahydro-isoindol-2-yl) ethyl) phenyl ] titanium, bis (cyclopentadienyl) -bis [2, 6-difluoro-3- (6- (9-carbazol-9-yl) hexyl) phenyl ] titanium, bis (cyclopentadienyl) -bis [2, 6-difluoro-3- (3- (2, 3,4,5,6,7,8, 9-octahydro-1-carbazol-9-yl) propyl) phenyl ] titanium, bis (cyclopentadienyl) -bis [2, 6-difluoro-3- (3- (4, 5,6, 7-tetrahydro-2-methyl-1-indol-1-yl) propyl) phenyl ] titanium, Bis (cyclopentadienyl) -bis [2, 6-difluoro-3- ((acetylamino) methyl) phenyl ] titanium, bis (cyclopentadienyl) -bis [2, 6-difluoro-3- (2- (propionylamino) ethyl) phenyl ] titanium, bis (cyclopentadienyl) -bis [2, 6-difluoro-3- (3- (acetylamino) propyl) phenyl ] titanium, bis (cyclopentadienyl) -bis [2, 6-difluoro-3- (4- (pivaloylamino) butyl) phenyl ] titanium, bis (cyclopentadienyl) -bis [2, 6-difluoro-3- (2, 2-dimethylpentanoylamino) ethyl) phenyl ] titanium, bis (cyclopentadienyl) -bis [2, 6-difluoro-3- (3- (benzoylamino) propyl) phenyl ] titanium, bis (cyclopentadienyl) -bis [2, 6-difluoro-3- ((2, 2-dimethylpentanamido) methyl) phenyl ] titanium, bis (cyclopentadienyl) -bis [2, 6-difluoro-3- (2, 2-dimethyl-3-chloropropionamido) ethyl) phenyl ] titanium, bis (cyclopentadienyl) -bis [2, 6-difluoro-3- ((2, 2-dimethyl-3-ethoxypropionylamino) methyl) phenyl ] titanium, bis (cyclopentadienyl) -bis [2, 6-difluoro-3- (2- (lauramido) ethyl) phenyl ] titanium, bis (cyclopentadienyl) -bis [2, 6-difluoro-3- (2- (N-allylmethylsulfonylamino) ethyl) phenyl ] titanium, Bis (cyclopentadienyl) -bis [2, 6-difluoro-3- (3- (N-isobutylphenylsulfonylamino) propyl) phenyl ] titanium, bis (cyclopentadienyl) -bis [2, 6-difluoro-3- ((methylsulfonylamino) methyl) phenyl ] titanium, bis (cyclopentadienyl) -bis [2, 6-difluoro-3- (3- (ethylsulfonylamino) propyl) phenyl ] titanium, bis (cyclopentadienyl) -bis [2, 6-difluoro-3- (2- (butylsulfonylamino) ethyl) phenyl ] titanium, bis (cyclopentadienyl) -bis [2, 6-difluoro-3- (4- (trissulfonylamino) propyl) phenyl ] titanium, Bis (. Eta. ⁵ -2, 4-cyclopentadienyl-1-yl) -bis (2, 6-difluoro-3- (1H-pyrrol-1-yl) phenyl) titanium, and the like. These titanocene-based photopolymerization initiators may be used singly or in combination of two or more.

As a commercial product of the titanocene-based photopolymerization initiator, JMT-784 (manufactured by Jin Maotai technologies Co., yueyang Co., ltd.; bis (. Eta. ⁵ -2, 4-cyclopenta-1-yl) -bis (2, 6-difluoro-3- (1H-pyrrol-1-yl) phenyl) titanium) and the like are mentioned.

The content of the titanocene-based photopolymerization initiator in the photosensitive thermosetting resin composition may be, for example, 0.01 to 10 parts by mass, preferably 0.02 to 8 parts by mass, and more preferably 0.05 to 5 parts by mass, per 100 parts by mass of the carboxyl group-containing resin, in terms of solid content. When the content of the titanocene-based photopolymerization initiator is 0.01 part by mass or more, sufficient photocuring can be achieved. In addition, if the amount is 10 parts by mass or less, curing unevenness tends to be suppressed. In one embodiment, the content of the titanocene-based photopolymerization initiator may be 2 parts by mass or less, 1 part by mass or less, or 0.5 part by mass or less.

The content ratio of the oxime ester-based photopolymerization initiator to the titanocene-based photopolymerization initiator in the photopolymerization initiator may be, for example, 1:10 to 10:1, preferably 1:8 to 8:1, more preferably 1:5 to 5:1, and still more preferably 1:2 to 2:1, as the oxime ester-based photopolymerization initiator. If the amount is within the above range, the balance between the surface curability and the deep curability is good, and a good pattern can be formed.

The total content of the titanocene-based photopolymerization initiator and the oxime ester-based photopolymerization initiator in the photosensitive thermosetting resin composition may be, for example, 0.01 parts by mass or more and 10 parts by mass or less, preferably 0.1 parts by mass or more and 2 parts by mass or less, more preferably 0.2 parts by mass or more and 1 part by mass or less, in terms of solid content, per 100 parts by mass of the carboxyl group-containing resin. When the total content of the titanocene-based photopolymerization initiator and the oxime ester-based photopolymerization initiator is 0.01 part by mass or more, sufficient photocuring can be achieved. In addition, if the amount is 10 parts by mass or less, curing unevenness tends to be suppressed.

The photopolymerization initiator may contain, in addition to the oxime ester-based photopolymerization initiator and the titanocene-based photopolymerization initiator, other photopolymerization initiators other than the oxime ester-based photopolymerization initiator and the titanocene-based photopolymerization initiator. Examples of the other photopolymerization initiator include benzophenone-based photopolymerization initiator, acetophenone-based photopolymerization initiator, aminoacetophenone-based photopolymerization initiator, benzoin ether-based photopolymerization initiator, benzyl ketal-based photopolymerization initiator, oxime ether-based photopolymerization initiator, alkylbenzene ketone-based photopolymerization initiator, and acylphosphine oxide-based photopolymerization initiator.

When the photopolymerization initiator includes other photopolymerization initiators, the content thereof may be, for example, 80 mass% or more and 99 mass% or less, and preferably 90 mass% or less and 97 mass% or less in terms of solid content with respect to the total mass of the photopolymerization initiator. In another embodiment, the content may be, for example, 10 mass% or less, preferably 1 mass% or less, and more preferably 0.1 mass% or less.

White pigment

The photosensitive thermosetting resin composition contains at least one of white pigments. By containing a white pigment, the cured product can be made white. Examples of the white pigment include zinc oxide, potassium titanate, zirconium oxide, antimony oxide, white lead, zinc sulfide, and lead titanate. From the viewpoints of reflectance and discoloration inhibition effect, it is preferable that the white pigment contains at least titanium oxide. As the titanium oxide, titanium oxide produced by a sulfuric acid method, a chlorine method, or the like, rutile titanium oxide, anatase titanium oxide, or titanium oxide obtained by subjecting a surface treatment with an aqueous metal oxide or a surface treatment with an organic compound to a surface treatment can be used. Among these titanium oxides, rutile titanium oxide is preferred from the viewpoint of photocatalytic activity. By using rutile titanium oxide, a more stable cured product (e.g., a solder resist) can be obtained. Specific examples of the rutile type titanium oxide include TR-600, TR-700, TR-750, TR-840 (manufactured by Fuji titanium Co., ltd.), R-550, R-580, R-630, R-820, CR-50, CR-60, CR-90 (manufactured by Shikon Co., ltd.), KR-270, KR-310, KR-380 (manufactured by titanium Co., ltd.), and the like. Among these rutile titanium oxides, titanium oxide having a surface treated with hydrous aluminum oxide or aluminum hydroxide is particularly preferably used from the viewpoints of dispersibility in the composition, storage stability and flame retardancy. The white pigment may be used alone or in combination of two or more.

The volume average particle diameter of the white pigment may be, for example, 10nm to 5 μm, preferably 100nm to 1 μm. The volume average particle diameter of the white pigment is measured as a particle diameter corresponding to 50% of the volume accumulation from the small diameter side in the cumulative particle size distribution based on the volume measured using, for example, a laser diffraction particle size distribution measuring apparatus.

The whiteness of the white pigment may be, for example, 80 or more, preferably 85 or more. The whiteness is measured, for example, using a spectrocolorimeter (PF 10, etc. manufactured by Nippon Denshoku industries Co., ltd.) according to "measurement method of ISO whiteness (diffuse blue reflectance)" of JIS P8148:2018.

The content of the white pigment in the photosensitive thermosetting resin composition may be, for example, 200 parts by mass or more and 1000 parts by mass or less, and preferably 250 parts by mass or more and 800 parts by mass or less, in terms of solid content, relative to 100 parts by mass of the carboxyl group-containing resin. If the content of the white pigment is 200 parts by mass or more, a sufficient reflectance can be achieved in the cured product. In addition, if the amount is 1000 parts by mass or less, the composition can be inhibited from increasing in viscosity, and the coating and molding properties are good, so that brittleness of the cured product tends to be inhibited.

Thermosetting resin

The photosensitive thermosetting resin composition contains at least one of thermosetting resins. As the thermosetting resin, a known and used resin such as an isocyanate compound, a blocked isocyanate compound, an amino resin, a maleimide compound, a benzoxazine resin, a carbodiimide resin, a cyclic carbonate compound, an epoxy resin, a polyfunctional oxetane compound, and an episulfide resin can be used. Among them, the thermosetting resin preferably has at least one of a plurality of cyclic ether groups and cyclic thioether groups (hereinafter, simply referred to as cyclic (thio) ether groups) in one molecule. These thermosetting components having a cyclic (thio) ether group are commercially available in many types, and various properties can be imparted according to the structure thereof.

The thermosetting resin having a plurality of cyclic (thio) ether groups in the molecule is a compound having at least one of a plurality of 3, 4 or 5-membered cyclic ether groups or cyclic thioether groups in the molecule, and examples thereof include a polyfunctional epoxy compound which is a compound having a plurality of epoxy groups in the molecule, a polyfunctional oxetane compound which is a compound having a plurality of oxetane groups in the molecule, an episulfide compound which is a compound having a plurality of thioether groups in the molecule, and the like.

Specific examples of the polyfunctional epoxy compound include bisphenol a type epoxy resin, hydrogenated bisphenol a type epoxy resin, brominated bisphenol a type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, novolac type epoxy resin, phenol novolac type epoxy resin, cresol novolac type epoxy resin, N-glycidyl type epoxy resin, bisphenol a novolac type epoxy resin, xylenol type epoxy resin, bisphenol type epoxy resin, chelate type epoxy resin, glyoxal type epoxy resin, amino group-containing epoxy resin, rubber modified epoxy resin, dicyclopentadiene phenol type epoxy resin, diglycidyl phthalate resin, heterocyclic type epoxy resin, tetraglycidyl xylene acyl ethane (TETRAGLYCIDYL XYLENOYL ETHANE) resin, silicone modified epoxy resin, epsilon-caprolactone modified epoxy resin, and the like. As the multifunctional epoxy resin, a resin having a halogen atom such as chlorine or bromine and an atom such as phosphorus introduced into its structure can be used. This can impart flame retardancy, for example. The multifunctional epoxy resin may be used alone or in combination of two or more.

Examples of the polyfunctional oxetane compound include polyfunctional oxetanes such as bis [ (3-methyl-3-oxetylmethoxy) methyl ] ether, bis [ (3-ethyl-3-oxetylmethoxy) methyl ] ether, 1, 4-bis [ (3-methyl-3-oxetylmethoxy) methyl ] benzene, 1, 4-bis [ (3-ethyl-3-oxetylmethoxy) methyl ] benzene, methyl (3-methyl-3-oxetanyl) acrylate, methyl (3-ethyl-3-oxetanyl) acrylate, methyl (3-methyl-3-oxetanyl) methacrylate, and oligomer or copolymer thereof, and etherified with hydroxyl-group-containing resins such as novolak resins, poly (p-hydroxystyrene), carbo-Lu Duo (Cardo) bisphenols, calixarenes, resorcinol calixarenes, silsesquioxane, and the like. In addition, copolymers of an unsaturated monomer having an oxetane ring and an alkyl (meth) acrylate and the like are also exemplified.

Examples of the episulfide resin include YL7000 (bisphenol A episulfide resin) manufactured by Mitsubishi chemical corporation. In addition, an episulfide resin obtained by replacing an oxygen atom of an epoxy group of a novolac-type epoxy resin with a sulfur atom by the same synthesis method can also be used.

The content of the thermosetting resin in the photosensitive thermosetting resin composition may be, for example, 10 parts by mass or more and 100 parts by mass or less, and preferably 20 parts by mass or more and 80 parts by mass or less, in terms of solid content, relative to 100 parts by mass of the carboxyl group-containing resin. When the content of the thermosetting resin is within the above range, good solder heat resistance can be obtained in the cured product of the photosensitive resin composition, and various characteristics, particularly electrical insulation properties, tend to be good when used as an insulating protective film for a printed wiring board.

The photosensitive thermosetting resin composition may contain a thermosetting catalyst in addition to the thermosetting resin. Examples of the heat curing catalyst include imidazole derivatives such as imidazole, 2-methylimidazole, 2-ethylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 4-phenylimidazole, 1-cyanoethyl-2-phenylimidazole, and 1- (2-cyanoethyl) -2-ethyl-4-methylimidazole, amine compounds such as dicyandiamide, benzyldimethylamine, 4- (dimethylamino) -N, N-dimethylbenzylamine, 4-methoxy-N, N-dimethylbenzylamine, and 4-methyl-N, N-dimethylbenzylamine, hydrazine compounds such as adipic acid dihydrazide and sebacic dihydrazide, and phosphorus compounds such as triphenylphosphine. Examples of the commercially available materials include 2MZ-A, 2MA-OK, 2PHZ-PW, 2P4BHZ-PW (trade names of imidazole compounds, all manufactured by Kagaku Kogyo Co., ltd.), DBU, DBN, U-CATSA102, U-CAT5002 (manufactured by San Apro Co., ltd., all of bicyclic amidine compounds and salts thereof), and the like. In particular, the present invention is not limited to these, and any material may be used as long as it is a thermosetting catalyst for an epoxy resin or an oxetane compound, or a material that promotes a reaction between at least one of an epoxy group and an oxetane group and a carboxyl group. In addition, S-triazine derivatives such as guanamine, acetoguanamine, benzoguanamine, melamine, 2, 4-diamino-6-methacryloxyethyl-S-triazine, 2-vinyl-2, 4-diamino-S-triazine, 2-vinyl-4, 6-diamino-S-triazine-isocyanuric acid adduct, and 2, 4-diamino-6-methacryloxyethyl-S-triazine-isocyanuric acid adduct can also be used. The heat curing catalyst may be used alone or in combination of two or more.

When the photosensitive thermosetting resin composition contains a thermosetting catalyst, the content of the thermosetting catalyst may be, for example, 0.1 to 20 parts by mass, preferably 0.5 to 15 parts by mass, per 100 parts by mass of the thermosetting resin in terms of solid content.

Further, if necessary, at least one filler selected from the group consisting of inorganic fillers and organic fillers may be contained in the photosensitive thermosetting resin composition for the purpose of improving the properties such as adhesion, hardness, heat resistance, and the like. Examples of the inorganic filler include barium sulfate, calcium carbonate, silicon oxide, amorphous silica, talc, clay, hydrotalcite, mica powder, and the like, and examples of the organic filler include silicon powder, nylon powder, fluorine powder, and the like. Among the above fillers, silica is particularly excellent in low hygroscopicity and low volume expansion. The silica may be a mixture of these, regardless of melting and crystallinity, and particularly in the case of silica surface-treated with a coupling agent or the like, electrical insulation can be improved, which is preferable. The average particle diameter of the filler is 25 μm or less, more preferably 10 μm or less, and still more preferably 3 μm or less. When the photosensitive thermosetting resin composition contains a filler, the content of the filler may be, for example, 150 parts by mass or less, preferably 50 parts by mass or less in terms of solid content, per 100 parts by mass of the carboxyl group-containing resin. If the filler content is in the above ratio, the cured film has good folding endurance.

The photosensitive thermosetting resin composition may contain other additives than the above components. Examples of the additives include tackifiers such as organobentonite and montmorillonite, defoamers such as silicone-based, fluorine-based and polymer-based, fiber-reinforced materials such as glass fiber, carbon fiber and boron nitride fiber, and the like. Further, if necessary, an adhesion promoter, a thermal polymerization inhibitor, a peroxide decomposer, an ultraviolet absorber, a thiazole-based silane coupling agent, a triazole-based silane coupling agent, a dispersant, a defoaming agent, a plasticizer, a foaming agent, a flame retardant, an antistatic agent, an anti-aging agent, an antibacterial/antifungal agent, and the like can be added.

The photosensitive thermosetting resin composition may further contain at least one of a radical extender and a peroxide decomposer, as required. This can suppress the functional degradation of the cured product. The free radical extender and peroxide decomposer may be so-called antioxidants.

Examples of the radical extender include phenol compounds such as hydroquinone, 4-t-butylcatechol, 2-t-butylhydroquinone, hydroquinone monomethyl ether, 2, 6-di-t-butyl-p-cresol, 2-methylene-bis (4-methyl-6-t-butylphenol), 1, 3-tris (2-methyl-4-hydroxy-5-t-butylphenyl) butane, 1,3, 5-trimethyl-2, 4, 6-tris (3, 5-di-t-butyl-4-hydroxybenzyl) benzene, 1,3, 5-tris (3 ',5' -di-t-butyl-4-hydroxybenzyl) -S-triazine-2, 4,6- (1 h,3h,5 h) trione, quinone compounds such as methoquinone (methoquinone), benzoquinone, and amine compounds such as bis (2, 6-tetramethyl-4-piperidyl) -sebacate and phenothiazine.

The radical supplements may be commercially available products, and include ADKSTAB (registered trademark) AO-30, ADKSTABAO-330, ADKSTABAO-20, ADKSTABLA-77, ADKSTABLA-57, ADKSTABLA-67, ADKSTABLA-68, ADKSTABLA-87 (all made by Ai Dike Co., ltd.), irganox (registered trademark) 1010, irganox 1035, irganox1076, irganox 1135, tinuvin (registered trademark) 111FDL, tinuvin 123, tinuvin144, tinuvin 152, tinuvin 292, tinuvin 5100 (all made by Bass Japanese Co., ltd.), and the like.

The ultraviolet absorber may be commercially available, and for example, Tinuvin PS、Tinuvin 99-2、Tinuvin 109、Tinuvin 384-2、Tinuvin 900、Tinuvin 928、Tinuvin 1130、Tinuvin 400、Tinuvin 405、Tinuvin 460、Tinuvin 479( is manufactured by basf japan).

The photosensitive thermosetting resin composition may further contain an organic solvent. By containing an organic solvent, the components can be easily dissolved or dispersed. In addition, the viscosity can be easily adjusted to be suitable for a method of applying such as coating. Examples of the organic solvent include aromatic solvents such as toluene, xylene, ethylbenzene and nitrobenzene, aliphatic hydrocarbon solvents such as cyclohexane, ether solvents such as diethylene glycol dimethyl ether and ethylene glycol diethyl ether, ester solvents such as carbitol acetate, propylene glycol methyl ether acetate, propylene glycol ethyl ether acetate, dipropylene glycol methyl ether acetate, methyl methoxypropionate, ethyl methoxypropionate, methyl ethoxypropionate, ethyl acetate, N-butyl acetate, isoamyl acetate, ethyl lactate and γ -butyrolactone, ketone solvents such as acetone, methyl ethyl ketone, cyclohexanone and isophorone, amide solvents such as N, N-dimethylformamide, N-dimethylacetamide and N-methylpyrrolidone, sulfoxide solvents such as dimethylsulfoxide, halogenated hydrocarbon solvents such as chloroform and methylene chloride, and the like. The organic solvent may be used alone or in combination of two or more. The content of the organic solvent may be appropriately set according to the desired viscosity or the like.

The photosensitive thermosetting resin composition is obtained by dissolving or dispersing the above components using a mixer, for example, a disperser, a kneader, a three-roll mill, a bead mill, or the like.

In one embodiment, the photosensitive thermosetting resin composition includes a photosensitive resin, a photopolymerization initiator, a white pigment, and an epoxy resin, the photosensitive resin includes a carboxyl group-containing resin, the photopolymerization initiator includes an oxime ester-based photopolymerization initiator and a titanocene-based photopolymerization initiator, and a mass ratio of a content of the white pigment to a content of the photosensitive resin is 1.2 or more and 5 or less, and a mass ratio of a total content of the oxime ester-based photopolymerization initiator and the titanocene-based photopolymerization initiator to a content of the white pigment may be 0.0004 or more and 0.002 or less. By having the content of the white pigment in the range and the photopolymerization initiator in the range, excellent whiteness and high reflectance at a wavelength of 450nm can be achieved.

Cured product

The cured product of the photosensitive thermosetting resin composition can exhibit high whiteness and excellent reflectance at a wavelength of 450 nm. The cured product of the photosensitive thermosetting resin composition can be obtained, for example, under the following curing conditions.

Curing conditions

The photosensitive thermosetting resin composition was applied to a substrate so that the film thickness after thermosetting became 55 μm, and then dried at 80℃for 30 minutes. Development (30 ℃ C., 0.2MPa, 1% by mass aqueous Na ₂CO₃) was carried out for 60 seconds using a high-pressure mercury lamp at 400mJ/cm ². Then, a cured product can be obtained by performing heat curing at 150 ℃ under 60 minutes.

The b ^* value of the L ^*a^*b^* color system of the cured product of the photosensitive thermosetting resin composition after thermosetting is 2.0 or less. The value of b ^* is preferably 1.8 or less, more preferably 1.5 or less. The b ^* value in the color system of L ^*a^*b^* was measured by a spectrocolorimeter (model: CM-5, manufactured by Konica Minolta, konicamata) on a cured product having a thickness of 55 μm produced under the above-mentioned production conditions. When the b ^* value of the cured product falls within the above range, yellowing due to heating tends to be suppressed.

The cured product has a reflectance of 85% or more at a wavelength of 450 nm. The reflectance at a wavelength of 450nm is preferably 88% or more. The reflectance at a wavelength of 450nm was measured by measuring 8mm in diameter by the SCI method of a spectrocolorimeter (manufactured by Konica Minolta, model: CM-5) for a cured product having a thickness of 55 μm produced under the above-mentioned curing conditions. When the reflectance of the cured product is within the above range, the light extraction efficiency in the display is improved, and the reflected light tends to be effectively utilized.

A cured product formed from the photosensitive thermosetting resin composition exhibits excellent heat resistance and can maintain whiteness and reflectance. Specifically, for example, Δeab ^* after the primary heat treatment (reflow step) is performed at a maximum temperature of 260 ℃ for 10 seconds may be 2.0 or less, and preferably 1.0 or less. Here, Δeab ^* is a value obtained by the following formula (1) using Δl ^*、Δa^*、Δb^*, which is a difference between L ^*、a^*、b^* before heat treatment and L ^*、a^*、b^* after heat treatment, and is an index indicating the degree of discoloration.

ΔEab^*＝((ΔL^*)²+(Δa^*)²+(Δb^*)²)^(1/2)(1)

The reflectance at a wavelength of 450nm may be reduced by, for example, 5% or less, and preferably 2% or less. The reflectance decrease range is calculated by subtracting the reflectance (%) measured in the cured product after the heat treatment from the reflectance (%) measured in the cured product before the heat treatment.

The photosensitive thermosetting resin composition can be applied to a printed board by a method selected from commonly used methods of application to form a resin composition layer. Further, the resin composition can be used in various forms and applications such as dry films and prepregs. Various solvents can be used depending on the method of use, etc., but in some cases, not only a good solvent but also a poor solvent may be used.

For the photosensitive thermosetting resin composition, for example, the organic solvent is used to adjust the viscosity suitable for the imparting method, and the composition is applied to a substrate, and the organic solvent contained in the composition is volatilized and dried (pre-dried) at a temperature of about 60 ℃ to 100 ℃, whereby a surface-dried resin composition layer can be formed. Examples of the application method include dip coating, flow coating, roll coating, bar coating, screen printing, curtain coating, and spray coating. The photosensitive thermosetting resin composition may be coated on a carrier film, and a substrate may be bonded with the dried photosensitive thermosetting resin composition as a film wound up to form a resin composition layer. Then, by contact (or non-contact method), the resist pattern (pattern image) is formed by selectively exposing the patterned photomask with active energy rays or directly exposing the pattern by a laser direct exposure machine, and developing the unexposed portion with a dilute alkali aqueous solution (for example, 0.3 to 3 mass% aqueous sodium carbonate solution). The exposure conditions are as follows. Further, for example, the carboxyl group (or further the phenolic hydroxyl group) of the carboxyl group-containing resin is reacted with the cyclic (thio) ether group of the thermosetting resin by heating at a temperature of about 140 ℃ to 180 ℃ and thermally curing, and flexibility and high reflectance are achieved in a high level in balance in addition to the properties of adhesion to a substrate, folding endurance, low warpage, electroless gold plating resistance, soldering heat resistance, electrical insulation and the like, and a white cured film in which decrease in reflectance and decrease in whiteness with time are suppressed is formed.

As the base material, a copper-clad laminate, a polyimide film, a PET film, a glass substrate, a ceramic substrate, a wafer sheet, or the like of all grades (FR-4, or the like) using a composite material such as a paper-phenol resin, a paper-epoxy resin, a glass cloth-epoxy resin, a glass-polyimide, a glass cloth/nonwoven fabric-epoxy resin, a glass cloth/paper-epoxy resin, a synthetic fiber-epoxy resin, a fluororesin-polyethylene-PPO-cyanate ester, or the like can be used. The circuit may be formed on the substrate, or a structure such as a transistor may be formed and mounted.

The volatilization drying performed after the photosensitive resin composition is applied can be performed using a hot air circulation type drying furnace, an IR furnace, a hot plate, a convection oven, or the like (a method of bringing hot air in a dryer into convection contact using a device having a heat source of an air heating system based on steam, and a method of spraying the hot air from a nozzle onto a support).

The photosensitive resin composition is applied to a substrate, and after drying by evaporation, the obtained resin composition layer is exposed to light (irradiation with active energy rays). The exposed portion (portion irradiated with active energy rays) of the resin composition layer is cured.

Examples of the exposure apparatus for irradiating the active energy rays include a direct drawing apparatus (for example, a laser direct imaging apparatus for directly drawing an image with laser light using CAD data from a computer), an exposure apparatus equipped with a metal halide lamp, an exposure apparatus equipped with a (ultra) high-pressure mercury lamp, an exposure apparatus equipped with a mercury short-arc lamp, and a direct drawing apparatus using an ultraviolet lamp such as a (ultra) high-pressure mercury lamp. The active energy ray may be a laser beam having a maximum wavelength in the range of 350nm to 450 nm. The active energy ray may be irradiated with, for example, a gas laser, a solid-state laser, or the like. The exposure amount may be appropriately selected depending on the film thickness, and is usually 5mJ/cm ² to 800mJ/cm ², and may preferably be in the range of 5mJ/cm ² to 500mJ/cm ². As the direct drawing device, for example, a device manufactured by obotech corporation of japan may be used, and any device may be used as long as it emits laser light having a maximum wavelength of 350nm to 450 nm.

Examples of the developing method include dipping, spraying, brushing, and the like. As the developer, an aqueous alkali solution such as potassium hydroxide, sodium carbonate, potassium carbonate, sodium phosphate, sodium silicate, ammonia, or an amine can be used.

The photosensitive thermosetting resin composition may be used in the form of a dry film having a resin composition layer formed by previously applying the photosensitive thermosetting resin composition to a film such as polyethylene terephthalate and drying, in addition to a method of directly applying the photosensitive thermosetting resin composition to a substrate in a liquid state. An example of using the photosensitive resin composition as a dry film is shown below.

Dry film

The dry film has a resin composition layer obtained by applying the photosensitive thermosetting resin composition to a film and drying the film. The dry film may have a structure in which a first film, a resin composition layer, and a releasable second film, which are used as needed, are laminated in this order. The resin composition layer is, for example, a layer obtained by applying a photosensitive thermosetting resin composition to the first film or the second film and drying the same. The dry film can be obtained by forming a resin composition layer on the first film and then laminating a second film thereon, or by laminating a laminate obtained by forming a resin composition layer on the second film on the first film.

As the first film, a thermoplastic film such as a polyester film having a thickness of 2 μm to 150 μm is used. The resin composition layer is formed by uniformly applying a photosensitive thermosetting resin composition to the first film or the second film with a thickness of 10 μm to 150 μm using a blade coater, a lip coater, a comma coater, a film coater, or the like, and drying the resultant film. As the second film, a polyethylene film, a polypropylene film, or the like can be used, but it is preferable that the bonding force with the resin composition layer is smaller than that of the first film.

In order to produce a protective film (permanent protective film) on a substrate using a dry film, the second film is peeled off, a resin composition layer is laminated on a circuit-formed substrate, and the resin composition layer is formed on the circuit-formed substrate using a laminator or the like. The cured coating film can be formed by exposing, developing and heat curing the resin composition layer formed in the same manner as described above. The first film may be peeled off before or after exposure.

Electronic component

The electronic component comprises a cured product of the photosensitive thermosetting resin composition. Examples of the electronic component include a printed wiring board and a light source module. The printed wiring board comprises a substrate having a patterned conductor, and a cured product of a photosensitive thermosetting resin composition disposed on the substrate. The cured product disposed on the substrate may be patterned into a desired shape. The light source module includes a printed wiring board and a semiconductor light emitting element disposed on the printed wiring board and connected to the pattern conductor. In the light source module, the semiconductor light emitting element may be covered with a cured resin layer. The cured resin layer covering the semiconductor light emitting element may contain, for example, silicone resin.

As another aspect of the present invention, the photosensitive thermosetting resin composition used in the production of a dry film or an electronic component, and the photosensitive thermosetting resin composition used in the production of a dry film or an electronic component are also included.

Examples

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

Hereinafter, a material for preparing a photosensitive thermosetting resin composition is prepared.

Carboxyl group-containing resin

Synthesis example 1 varnish A-1

2400G (3 moles) of a polycarbonate diol derived from 1, 5-pentanediol and 1, 6-hexanediol (TJ 5650J, number average molecular weight 800, manufactured by Asahi Kabushiki Kaisha), 603g (4.5 moles) of dimethylolpropionic acid, and 238g (2.6 moles) of 2-hydroxyethyl acrylate as a monohydroxy compound were charged into a reaction vessel equipped with a stirring device, a thermometer, and a condenser. Then, 1887g (8.5 moles) of isophorone diisocyanate (polyisocyanate) was charged, heated to 60℃with stirring and stopped, and the reaction was terminated after the stirring was continued at 80℃with reheating at the point where the temperature in the reaction vessel began to drop, and the disappearance of the absorption spectrum (2280 cm ^-1) of the isocyanate group was confirmed by infrared absorption spectrum. The solid content was 50 mass%, and carbitol acetate was added thereto to obtain varnish A-1. The acid value of the solid matter was 50mgKOH/g, and the weight-average molecular weight Mw was about 17000.

Synthesis example 2 varnish A-2

220G of cresol novolac type epoxy resin (EPICLON N-695, epoxy equivalent: 220g/eq. Manufactured by DIC Co., ltd.) was placed in a four-necked flask equipped with a stirrer and a reflux condenser, 214g of carbitol acetate was added, and the mixture was heated and dissolved. Then, 0.1g of hydroquinone as a polymerization inhibitor and 2.0g of dimethylbenzylamine as a reaction catalyst were added. The mixture was heated to 95-105 ℃ and acrylic acid 72g was slowly added dropwise to react for 16 hours. The reaction product is cooled to 80-90 ℃, 106g of tetrahydrophthalic anhydride is added to react for 8 hours, and the reaction product is taken out after cooling. The solid content of the thus-obtained carboxyl group-containing resin varnish A-2 was 65%, the acid value of the solid was 100mgKOH/g, and the weight-average molecular weight Mw was about 3500.

Photosensitive compound

BPE-900, ethoxylated bisphenol A dimethacrylate, manufactured by Xinzhongcun chemical Co., ltd.

Photopolymerization initiator

Oxime ester system

ADEKA ARKLS NCI-930, ai Dike, 1-4- [ [4- (2-hydroxyethoxy) phenyl ] thio ] phenyl ] -1, 2-propanedione 2- (O-acetyloxime).

ADEKA ARKLS NCI-730, ai Dike, inc.

Irgacure OXE04, manufactured by Basf Japan Co.

Irgacure OXE02 manufactured by Basoff Japan Co., ltd.; 1- [ 9-ethyl-6- (2-methylbenzoyl) -9H-carbazol-3-yl ] ethanone 1- (O-acetyloxime).

Titanium dicyclopentadiene system

JMT-784, manufactured by Jin Maotai technologies Inc., yueyang, inc., bis (. Eta. ⁵ -2, 4-cyclopenta-1-yl) -bis (2, 6-difluoro-3- (1H-pyrrol-1-yl) phenyl) titanium).

Alkylbenzene ketone system

Omnirad 184: 1-hydroxycyclohexyl phenyl ketone, manufactured by IGM Japan Co.

Alpha-aminoacetophenone system

Omnirad 379, manufactured by IGM Japan Co., ltd., 2-dimethylamino-2- (4-methylbenzyl) -1- (4-morpholin-4-yl-phenyl) -butan-1-one.

Omnirad 907, manufactured by IGM Japan Co., ltd., 2-methyl-1- [4- (methylthio) phenyl ] -2-morpholinopropan-1-one.

White pigment

CR-90, from Shiyuan Co., ltd., rutile type titanium oxide.

Thermosetting resin

JER834, mitsubishi chemical Co., ltd., bisphenol A type epoxy resin, epoxy equivalent weight 250g/eq.

Heat curing catalyst

DICY7, dicyandiamide, mitsubishi chemical Co.

Wetting dispersant

Disperbyk-111 manufactured by Pick chemical Japan Co.

Defoaming agent

KS-66, manufactured by Xinyue chemical Co., ltd., silicone oil complex type antifoaming agent.

Preparation of photosensitive resin composition

Using the obtained varnishes A-1 and A-2, the respective components shown in Table 1 were blended in the proportions (parts by mass) described, premixed by a mixer, and kneaded by a three-roll mill, to prepare photosensitive thermosetting resin compositions of examples 1 to 13 and comparative examples 1 to 5. Values in the tables are parts by mass unless otherwise indicated. In table 1 and table 2, "-" indicates that it was not added or evaluated (because it was not evaluated).

The photosensitive thermosetting resin compositions of examples 1 to 13 and comparative examples 1 to 5 thus obtained were evaluated as follows. The results are shown together in tables 1 and 2.

Fabrication of evaluation substrate

The photosensitive thermosetting resin compositions of examples 1 to 13 and comparative examples 1 to 5 were printed twice on an all-copper substrate by screen printing, and a coating film was formed so that the total film thickness after thermosetting became 55 μm. Specifically, the entire surface of the all-copper substrate was coated by screen printing, and dried for 10 minutes using a hot air circulation type drying oven at 80 ℃ to form a first layer, and the entire surface was further coated by screen printing, and dried for 20 minutes using a hot air circulation type drying oven at 80 ℃ to form a second layer. The formed coating film was exposed to light with an optimum exposure amount using an exposure apparatus (Mms 60: manufactured by velcade corporation (ORC MANUFACTURING co., ltd.), and developed for 60 seconds (30 ℃, 0.2MPa, 1 mass% aqueous Na ₂CO₃ solution). Then, a resin layer was formed by thermally curing the resin layer at 150 ℃ for 60 minutes using a hot air circulation type drying furnace, and an evaluation substrate was produced. The optimum exposure amount was set to a pattern of 15 to 20 exposure levels by exposing the dry coating film with a high-pressure mercury lamp-mounted exposure apparatus (Mms 60: manufactured by the company corporation) via a Stouffer 41-level stepwise exposure meter (StepTablet) and developing for 60 seconds with a 1 mass% aqueous Na ₂CO₃ solution having a jet pressure of 0.2MPa and a liquid temperature of 30 ℃.

Evaluation of surface curability

In addition to setting the exposure to "400mJ/cm ²" from the "optimum exposure", the surface of the substrate was visually observed after the production of the evaluation substrate, after the production and before the heat curing. The evaluation criteria for the surface curability are as follows.

The surface is not rough and is good.

Roughness is observed in a portion of the surface.

Roughness was observed over the whole surface.

Evaluation of reflectance

The reflectance and b-type of the resin layer formed on each evaluation substrate obtained in the production of the evaluation substrate were measured at a diameter of 8mm by the SCI method of a spectrocolorimeter (manufactured by Konica Minolta, model: CM-5). The measurement results are shown in the "reflectance" and b ^* lines in table 1.

The above-mentioned evaluation substrate was subjected to a one-time reflow process at a maximum temperature of 260℃for 10 seconds using a reflow apparatus (NIS-20-82C, manufactured by Ai Taike electronic technologies Co., ltd.). Then, the reflectance and b ^* were measured in the same manner as described above. The measurement results are shown in Table 1 as reflectance after heat resistance test and b ^* after heat resistance test.

Evaluation of ΔEab ^*

Δeab ^* is a value obtained by the following formula (1) using L ^*、a^*、b^* before reflow and L ^*、a^*、b^* after reflow, and is an index indicating the degree of discoloration. Measured by a spectrocolorimeter (model: CM-5, manufactured by Konikoku Meida Co.). The calculation results are shown in row Δeab ^* in table 1.

ΔEab^*＝((ΔL^*)²+(Δa^*)²+(Δb^*)²)^(1/2) (1)

Evaluation of solder Heat resistance

Rosin-based flux was applied to each of the above-obtained substrates for evaluation, and immersed in a solder bath set at 260 ℃ in advance for 10 seconds. Then, after the flux was washed with the modified alcohol, the swelling and peeling of the resin layer were visually evaluated. The evaluation criteria for heat resistance are as follows.

After 10 seconds of impregnation, the resin layer did not swell and delaminate.

After 5 seconds of impregnation, the resin layer did not swell and delaminate.

After 5 seconds of impregnation, the swelling and peeling of the resin layer was evident.

Evaluation of deep curability (undercut (Undercut))

The photosensitive thermosetting resin compositions of examples 1 to 13 and comparative examples 1 to 5 were printed twice on an all-copper substrate by screen printing, and a coating film was formed so that the total film thickness after thermosetting became 55 μm. Specifically, the entire surface of the all-copper substrate was coated by screen printing, and dried for 10 minutes using a hot air circulation type drying oven at 80 ℃ to form a first layer, and the entire surface was further coated by screen printing, and dried for 20 minutes using a hot air circulation type drying oven at 80 ℃ to form a second layer. The formed coating film was subjected to pattern exposure at 400mJ/cm ² using an exposure apparatus (Mms 60: manufactured by Kelvin corporation) mounted on a high-pressure mercury lamp, and developed for 60 seconds (30 ℃, 0.2MPa, 1% by mass aqueous Na ₂CO₃ solution). The cross section of the opening portion of the obtained pattern was observed, and the lengths of the upper portion (air side) and the lower portion (substrate side) were measured. Undercut was calculated by the following formula and the deep curability was evaluated.

Side etching= (length of upper part-length of lower part)/2

TABLE 1

TABLE 2

As described above, according to the present invention, it is possible to provide a photosensitive resin composition which is less likely to cause discoloration after a heating step and which can maintain a high reflectance. In particular, the amount of the oxime ester photopolymerization initiator and the titanocene photopolymerization initiator blended was small, the amount of the white pigment blended was higher than that of examples 2 and 4 in example 3, and the b ^* value, the surface curability and the weld heat resistance were all excellent. This is considered to be because, for example, the synergistic effect of the oxime ester photopolymerization initiator and the titanocene initiator can exhibit desired properties even with a small amount of the initiator.

In comparative example 1, although a coating film could be formed, a strong enough pattern for evaluating undercut did not remain after development, and thus deep curability could not be evaluated. In comparative example 2, since a coating film could not be formed, all evaluation items could not be evaluated. In comparative examples 4 and 5, the resin layer could not be formed with the exposure amount evaluated for the surface curability and deep curability, and therefore could not be evaluated.

The disclosure of Japanese patent application No. 2023-055267 (application date: 2023, 3, 30) is incorporated by reference in its entirety into this specification. All documents, patent applications and technical standards cited in this specification are incorporated by reference to the same extent as if each document, patent application and technical standard were specifically and individually indicated to be incorporated by reference.

Claims (5)

1. A photosensitive thermosetting resin composition comprising a carboxyl group-containing resin, a photopolymerization initiator, a white pigment, and a thermosetting resin, wherein,

The photopolymerization initiator comprises an oxime ester photopolymerization initiator and a titanocene photopolymerization initiator,

The thermosetting resin comprises an epoxy resin and,

The b ^* value in the L ^*a^*b^* color system of the cured product of the photosensitive thermosetting resin composition after thermosetting is 2.0 or less, and the reflectance at the wavelength of 450nm is 85% or more.

2. The photosensitive thermosetting resin composition according to claim 1, wherein a mass-based content ratio of the oxime ester-based photopolymerization initiator to the titanocene-based photopolymerization initiator is in a range of 1:10 to 10:1.

3. A dry film comprising a resin layer obtained by applying the photosensitive thermosetting resin composition according to claim 1 or 2 to a first film and drying the same.

4. A cured product obtained by curing the photosensitive thermosetting resin composition according to claim 1 or 2.

5. An electronic component comprising the cured product according to claim 4.