JP5799799B2 - Photosensitive resin composition, photosensitive element, resist pattern forming method and printed wiring board manufacturing method - Google Patents

Description

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

  In the field of manufacturing printed wiring boards, photosensitive resin compositions are widely used as resist materials used for etching and plating. A photosensitive resin composition includes a support film and a layer (hereinafter, referred to as “photosensitive resin composition layer”) formed using the photosensitive resin composition on the support film. Often used as a laminate.

  A printed wiring board is manufactured as follows, for example. First, the photosensitive resin composition layer of the photosensitive element is laminated (laminated) on the circuit forming substrate (lamination step). Next, after peeling off and removing the support film, the exposed portion is cured by irradiating a predetermined portion of the photosensitive resin composition layer with actinic rays (exposure step). Thereafter, by removing (developing) the unexposed portion from the substrate, a resist pattern made of a cured product of the photosensitive resin composition is formed on the substrate (developing step). An etching process or a plating process is performed on the obtained resist pattern to form a circuit on the substrate (circuit forming process), and finally the resist is peeled and removed to produce a printed wiring board (peeling process).

  As an exposure method, conventionally, a method of exposing via a photomask using a mercury lamp as a light source has been used, but recently, digital data of a pattern called DLP (Digital Light Processing) or LDI (Laser Direct Imaging) is used. A direct drawing exposure method for drawing directly on the photosensitive resin composition layer has begun to be used. This direct drawing exposure method has a better alignment accuracy than an exposure method through a photomask, and a high-definition pattern can be obtained.

  By the way, various characteristics are required for the photosensitive resin composition. For example, in the exposure process, it is necessary to shorten the exposure time in order to improve production efficiency. However, in the direct drawing exposure method described above, a monochromatic light such as a laser is used as a light source, and light is irradiated while scanning the substrate. Therefore, there is a tendency that much exposure time is required as compared with an exposure method using a conventional photomask. Therefore, in order to shorten the exposure time and increase the production efficiency, it is necessary to improve the sensitivity of the photosensitive resin composition than before.

  Conventionally, various photosensitive resin compositions have been studied in response to these requirements. For example, Patent Documents 1 to 6 disclose a photosensitive resin composition having improved sensitivity and the like by using a specific photopolymerization initiator or a sensitizing dye.

JP 2007-279381 A International Publication No. 07/004619 Pamphlet International Publication No. 10 / 126,006 International Publication No. 09/147031 Pamphlet JP 2010-526846 A Special table 2010-527338 gazette

  With the recent increase in the density of printed wiring boards, there is an increasing demand for a photosensitive resin composition excellent in resolution (resolution) and adhesion. In particular, a photosensitive resin composition capable of forming a resist pattern having an L / S (line width / space width) of about 10/10 (unit: μm) in the manufacture of a package substrate is required.

  However, the conventional photosensitive element has room for improvement in forming a resist pattern having excellent resolution and adhesion while achieving high sensitivity.

  The present invention has been made in view of the above-mentioned problems of the prior art, and is a photosensitive resin composition excellent in sensitivity, resolution, and adhesion, a photosensitive element using the same, a method for forming a resist pattern, and a printed wiring board. A manufacturing method is provided.

  The present invention includes (A) a binder polymer, (B) a photopolymerizable compound, and (C) a photopolymerization initiator, wherein (C) the photopolymerization initiator is represented by the following formula (1). The photosensitive resin composition containing is provided.

［式（１）中、Ｒ^１及びＲ^２は、それぞれ独立に下記式（１ａ）又は（１ｂ）で表される基を示す。］

[In Formula (1), R ¹ and R ² each independently represent a group represented by the following Formula (1a) or (1b). ]

［式（１ａ）及び（１ｂ）中、Ｒは、それぞれ独立に炭素数１〜２０のアルキル基又はフェニル基を示し、複数存在するＲは同一でも異なっていてもよい。］

[In formulas (1a) and (1b), R independently represents an alkyl group having 1 to 20 carbon atoms or a phenyl group, and a plurality of R may be the same or different. ]

  Since the compound represented by the above formula (1) has relatively large absorption not only for light having a wavelength of 350 to 365 nm but also for light having a wavelength of 390 to 410 nm, the photosensitive resin composition of the present invention has a wavelength. Good sensitivity can be obtained for light of 350 to 410 nm. In addition, by including the compound represented by the above formula (1), the photosensitive resin composition of the present invention not only has excellent sensitivity, resolution and adhesion, but also has peeling properties, plating formability and plating contamination. Can be improved.

  Moreover, in the photosensitive resin composition of this invention, it is preferable that the maximum absorption wavelength of the compound represented by said Formula (1) is 350-410 nm. As a result, good sensitivity can be obtained with respect to light having a wavelength of 350 to 410 nm, and at the same time, absorption on the long wavelength side of 500 nm or more is reduced, and stability under yellow light is improved.

  Moreover, in the photosensitive resin composition of this invention, it is preferable that the said (A) binder polymer contains (meth) acrylic acid and styrene or a styrene derivative as a copolymerization component. Thereby, the alkali developability, resolution, and adhesiveness of the photosensitive resin composition are further improved.

  Moreover, this invention provides a photosensitive element provided with a support film and the photosensitive resin composition layer which consists of the said photosensitive resin composition formed on this support film. By using such a photosensitive element, it is possible to efficiently form a resist pattern having good sensitivity, resolution, adhesion, peeling characteristics, plating formability and plating contamination.

  The present invention also includes a laminating step of laminating a photosensitive resin composition layer comprising the above photosensitive resin composition on a substrate, an exposure step of irradiating a predetermined portion of the photosensitive resin composition layer with actinic rays, a photosensitive layer Forming a resist pattern made of a cured product of the photosensitive resin composition on the substrate by removing portions other than the predetermined portion of the photosensitive resin composition layer from the substrate, thereby forming a resist pattern. Provide a method. According to the above method, it is possible to efficiently form a resist pattern having good sensitivity, resolution, adhesion, peeling characteristics, plating formability, and plating contamination.

  Moreover, this invention provides the manufacturing method of a printed wiring board including the process of etching or plating the board | substrate with which the resist pattern was formed by the said method. According to this manufacturing method, a printed wiring board having high-density wiring such as a high-density package substrate can be efficiently manufactured.

  ADVANTAGE OF THE INVENTION According to this invention, the photosensitive resin composition excellent in a sensitivity, resolution, and adhesiveness, the photosensitive element using the same, the formation method of a resist pattern, and the manufacturing method of a printed wiring board can be provided.

It is a schematic cross section showing one embodiment of a photosensitive element. It is a diagram showing ¹ H-NMR spectrum of the product according to the present embodiment (C-1).

  Hereinafter, the best mode for carrying out the present invention will be described in detail. However, the present invention is not limited to the following embodiments. In this specification, (meth) acrylic acid means acrylic acid or methacrylic acid, (meth) acrylate means acrylate or methacrylate, and (meth) acryloyl group means acryloyl group or methacryloyl. Means group. The (poly) oxyethylene chain means an oxyethylene group or a polyoxyethylene chain, and the (poly) oxypropylene chain means an oxypropylene group or a polyoxypropylene chain. Further, “EO-modified” means a compound having a (poly) oxyethylene chain, and “PO-modified” means a compound having a (poly) oxypropylene chain. “PO-modified” means a compound having both a (poly) oxyethylene chain and a (poly) oxypropylene chain.

(Photosensitive resin composition)
The photosensitive resin composition of this embodiment contains (A) a binder polymer, (B) a photopolymerizable compound, and (C) a photopolymerizable compound, and (C) the photopolymerizable compound is represented by the above formula (1). Including the compound represented.

  First, the binder polymer as the component (A) will be described. Examples of the (A) binder polymer include acrylic resins, styrene resins, epoxy resins, amide resins, amide epoxy resins, alkyd resins, and phenol resins. From the viewpoint of alkali developability, an acrylic resin is preferable. These can be used alone or in combination of two or more.

  (A) The binder polymer can be produced, for example, by radical polymerization of a polymerizable monomer. Examples of the polymerizable monomer include polymerizable styrene derivatives such as styrene, vinyltoluene, α-methylstyrene, p-methylstyrene, and p-ethylstyrene; (meth) acrylic acid, α-bromo (meth) Acrylic acid, α-chloro (meth) acrylic acid, β-furyl (meth) acrylic acid, β-styryl (meth) acrylic acid, (meth) acrylic acid alkyl ester, (meth) acrylic acid cycloalkyl ester, (meth) Benzyl acrylate, furfuryl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, glycidyl (meth) acrylate 2,2,2-trifluoroethyl (meth) acryl Rate, (meth) acrylic acid monomers such as 2,2,3,3-tetrafluoropropyl (meth) acrylate; esters of vinyl alcohol such as vinyl-n-butyl ether; maleic acid, maleic anhydride, Examples thereof include maleic monomers such as monomethyl maleate, monoethyl maleate and monoisopropyl maleate; acrylamide, acrylonitrile, fumaric acid, cinnamic acid, α-cyanocinnamic acid, itaconic acid, crotonic acid and propiolic acid. These are used alone or in combination of two or more.

  Examples of the (meth) acrylic acid alkyl ester include, for example, methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, and n- (meth) acrylate. Butyl, tert-butyl (meth) acrylate, pentyl (meth) acrylate, hexyl (meth) acrylate, heptyl (meth) acrylate, octyl (meth) acrylate, 2-ethylhexyl (meth) acrylate and these Structural isomers. These can be used alone or in combination of two or more.

  (A) The binder polymer preferably contains a carboxyl group from the viewpoint of alkali developability, and is produced, for example, by radical polymerization of a polymerizable monomer having a carboxyl group and another polymerizable monomer. be able to. As the polymerizable monomer having a carboxyl group, (meth) acrylic acid is preferable.

  (A) It is preferable that a binder polymer contains styrene or a styrene derivative as a copolymerization component from a viewpoint of an adhesive improvement. When the styrene or styrene derivative is included as a copolymerization component, the content may include 5 to 70% by mass with respect to the entire nonvolatile content of the component (A) from the viewpoint of improving the adhesion and release characteristics in a balanced manner. The content is preferably 10 to 65% by mass, and more preferably 15 to 60% by mass. 5 mass% or more is preferable at the point which is excellent in adhesiveness, 10 mass% or more is more preferable, and 15 mass% or more is still more preferable. In the point which is excellent in peeling characteristics, 70 mass% or less is preferable, 65 mass% or less is more preferable, and 60 mass% or less is still more preferable.

  Moreover, it is preferable that (A) binder polymer contains (meth) acrylic acid benzyl ester as a copolymerization component. When (meth) acrylic acid benzyl ester is included as a copolymerization component, the content thereof is 5 to 70% by mass with respect to the entire nonvolatile content of component (A), from the viewpoint of improving the resolution and release characteristics in a balanced manner. Is preferable, it is more preferably 10 to 65% by mass, and even more preferably 15 to 60% by mass. In terms of excellent resolution, 5% by mass or more is preferable, 10% by mass or more is more preferable, and 15% by mass or more is even more preferable. In the point which is excellent in peeling characteristics, 70 mass% or less is preferable, 65 mass% or less is more preferable, and 60 mass% or less is still more preferable.

  The weight average molecular weight of the (A) binder polymer is preferably 5,000 to 300,000, more preferably 10,000 to 150,000, still more preferably 20,000 to 80,000, and particularly preferably 30,000 to 70,000. . In terms of excellent developer resistance, it is preferably 5000 or more, more preferably 10,000 or more, still more preferably 20000 or more, and particularly preferably 30000 or more. Moreover, in the point which is excellent in resolution and peeling characteristics, 300,000 or less is preferable, 150,000 or less is more preferable, 80000 or less is further more preferable, and 70000 or less is especially preferable. In addition, the weight average molecular weight and number average molecular weight in this embodiment are measured by gel permeation chromatography (GPC), and values converted to standard polystyrene are used.

  The acid value of the component (A) is preferably 50 to 250 mgKOH / g, more preferably 100 to 230 mgKOH / g, and still more preferably 130 to 200 mgKOH / g. In terms of excellent developability, 50 mgKOH / g or more is preferable, 100 mgKOH / g or more is more preferable, and 130 mgKOH / g or more is even more preferable. Moreover, in the point which is excellent in the developing solution resistance (adhesion) of the resist after photocuring, 250 mgKOH / g or less is preferable, 230 mgKOH / g or less is more preferable, and 200 mgKOH / g or less is still more preferable.

  The (A) binder polymer preferably has a dispersity (weight average molecular weight / number average molecular weight) of 1.0 to 3.0 in terms of excellent adhesion and resolution, and is 1.0 to 2.0. More preferably.

  (A) A binder polymer is used individually or in combination of 2 or more types. Examples of the binder polymer used in combination of two or more types include two or more binder polymers composed of different copolymerization components, two or more binder polymers having different weight average molecular weights, and two or more types of binder polymers having different dispersities. Examples thereof include a binder polymer. A polymer having a multimode molecular weight distribution described in JP-A No. 11-327137 can also be used.

  In addition, the (A) binder polymer may have a photosensitive group as necessary.

  The content of the component (A) is preferably 30 to 70 parts by mass with respect to 100 parts by mass of the total amount of the component (A) and the component (B) in terms of excellent film formability, sensitivity, and resolution. It is more preferable to set it as -65 mass parts, and it is still more preferable to set it as 40-60 mass parts.

  Next, the photopolymerizable compound as the component (B) will be described. The component (B) is not particularly limited as long as it can be photocrosslinked, but a compound having an ethylenically unsaturated bond is preferably used. The compound having an ethylenically unsaturated bond includes a compound having one ethylenically unsaturated bond in the molecule, a compound having two ethylenically unsaturated bonds in the molecule, and three ethylenically unsaturated bonds in the molecule. Examples thereof include the compounds described above.

  The component (B) preferably contains 40% by mass or more, more preferably 60% by mass or more of the compound having two ethylenically unsaturated bonds in the molecule with respect to the mass of the entire component (B).

  Examples of compounds having two ethylenically unsaturated bonds in the molecule include bisphenol A di (meth) acrylate compounds, hydrogenated bisphenol A di (meth) acrylate compounds, and di (meth) acrylates having urethane bonds in the molecule. Examples include compounds, polyalkylene glycol di (meth) acrylate compounds having both (poly) oxyethylene chains and (poly) oxypropylene chains in the molecule, and trimethylolpropane di (meth) acrylate.

  Among the above, the component (B) preferably contains a bisphenol A-based di (meth) acrylate compound from the viewpoint of improving resolution and peeling characteristics.

  Examples of the bisphenol A di (meth) acrylate compound include compounds represented by the following formula (2).

In formula (2), R ³ and R ⁴ each independently represent a hydrogen atom or a methyl group. XO and YO each independently represent an oxyethylene group or an oxypropylene group. (XO) m ₁ , (XO) m ₂ , (YO) n ₁ and (YO) n ₂ each independently represent a (poly) oxyethylene chain or a (poly) oxypropylene chain. _{m 1, m 2, n 1} , n 2 are each independently an integer of 0 to 40. When XO is an oxyethylene group and YO is an oxypropylene group, m ₁ + m ₂ is 1 to 40, n ₁ + n ₂ is 0 to 20, and when XO is an oxypropylene group and YO is an oxyethylene group, m ₁ + _{m 2} is _{0~20, n} 1 + n ₂ is 1 to 40. The polymerization mode of the (poly) oxyethylene chain or (poly) oxypropylene chain may be random or block. In terms of further improving the resolution and adhesion, and compounds which are among the compounds represented by formula _{(2), m 1 + m} 2 is 1 to 6 _Deli, n 1 + _{n 2} is _{0, m} 1 + m It is preferable to use in combination with a compound in which ₂ is 8 to 40 and n ₁ + n ₂ is 0 to 20.

  Among the compounds represented by the formula (2), 2,2-bis (4- (methacryloxypentaethoxy) phenyl) propane is BPE-500 (trade name, manufactured by Shin-Nakamura Chemical Co., Ltd.) or FA- It is commercially available as 321M (trade name, manufactured by Hitachi Chemical Co., Ltd.), and 2,2-bis (4- (methacryloxypentadecaethoxy) phenyl) propane is BPE-1300 (Shin Nakamura Chemical Co., Ltd.) It is commercially available as a product name. These may be used alone or in any combination of two or more.

  Moreover, it is preferable that (B) component contains polyalkylene glycol di (meth) acrylate from a viewpoint of improving the flexibility of the hardened | cured material (cured film) of the photosensitive resin composition. As content of polyalkylene glycol di (meth) acrylate, it is preferable that it is 3-70 mass% with respect to the mass of the whole (B) component, and it is more preferable that it is 5-60 mass%.

  As the polyalkylene glycol di (meth) acrylate, polyalkylene glycol di (meth) acrylate having both a (poly) oxyethylene chain and a (poly) oxypropylene chain in the molecule is preferable. In the molecule of polyalkylene glycol di (meth) acrylate, the (poly) oxyethylene chain and the (poly) oxypropylene chain may be continuously present in blocks or randomly. The oxypropylene group in the (poly) oxypropylene chain may be either an oxy-n-propylene group or an oxyisopropylene group. In the (poly) oxyisopropylene chain, the secondary carbon of the propylene group may be bonded to an oxygen atom, or the primary carbon may be bonded to an oxygen atom.

  The polyalkylene glycol di (meth) acrylate further includes (poly) oxy-n-butylene chain, (poly) oxyisobutylene chain, (poly) oxy-n-pentylene chain, (poly) oxyhexylene chain, It may have a (poly) oxyalkylene chain having about 4 to 6 carbon atoms, which is a structural isomer or the like.

  As the polyalkylene glycol di (meth) acrylate, a compound represented by the following formula (3), (4) or (5) is particularly preferable. These can be used alone or in combination of two or more.

In formulas (3), (4) and (5), R ^{5 to} R ¹⁰ each independently represent a hydrogen atom or a methyl group, EO represents an oxyethylene group, and PO represents an oxypropylene group. r ¹ , r ² , r ³ and r ⁴ represent the number of repeating structural units composed of oxyethylene groups, s ¹ , s ² , s ³ and s ⁴ represent the number of repeating structural units composed of oxypropylene groups, The total number of repeating oxyethylene groups r ¹ + r ² , r ³ and r ⁴ (average value) each independently represents an integer of 1 to 30, and the total number of repeating oxypropylene groups s ¹ , s ² + s ³ and s ⁴ (average) (Value) each independently represents an integer of 1 to 30.

In the compound represented by the formula (3), (4) or (5), the total number of repeating oxyethylene groups r ¹ + r ² , r ³ and r ⁴ is an integer of 1 to 30, preferably 1 to 10. It is an integer, More preferably, it is an integer of 4-9, More preferably, it is an integer of 5-8. When the total number of repetitions exceeds 30, sufficient resolution, adhesion, and resist shape tend to be difficult to obtain.

The total number of repeating s ¹ , s ² + s ³ and s ⁴ of the oxypropylene group is an integer of 1 to 30, preferably an integer of 5 to 20, more preferably an integer of 8 to 16, and still more preferably. Is an integer from 10 to 14. When the total number of repetitions exceeds 30, it is difficult to obtain sufficient resolution, and sludge tends to be easily generated.

As the compound represented by the formula (3), R ⁵ and R ⁶ = methyl group, r ¹ + r ² = 6 (average value), s ¹ = 12 (average value) vinyl compound (Hitachi Chemical Co., Ltd.) ), Product name “FA-023M”) and the like. As the compound represented by the formula (4), R ⁷ and R ⁸ = methyl group, r ³ = 6 (average value), s ² + s ³ = 12 (average value) vinyl compound (Hitachi Chemical Industry Co., Ltd.) ), Product name “FA-024M”) and the like. As the compound represented by the formula (5), R ⁹ and R ¹⁰ = hydrogen atom, r ⁴ = 1 (average value), s ⁴ = 9 (average value) vinyl compound (Shin Nakamura Chemical Co., Ltd.) Manufactured, sample name “NK ester HEMA-9P”) and the like. These can be used alone or in combination of two or more.

  In the case where the component (B) contains a photopolymerizable compound having one ethylenically unsaturated bond in the molecule, the content is from the viewpoint of improving the resolution, adhesion, resist shape and release characteristics after curing in a well-balanced manner. It is preferable that it is 1-30 mass% with respect to the mass of the whole (B) component, it is more preferable that it is 3-25 mass%, and it is still more preferable that it is 5-20 mass%.

  Examples of the compound having one ethylenically unsaturated bond in the molecule include nonylphenoxypolyethyleneoxyacrylate, phthalic acid compounds, and (meth) acrylic acid alkyl esters.

  Among these, the component (B) preferably contains nonylphenoxypolyethyleneoxyacrylate or a phthalic acid-based compound from the viewpoint of improving the resolution, adhesion, resist shape, and release property after curing in a well-balanced manner.

  Nonylphenoxypolyethyleneoxyacrylate includes nonylphenoxytriethyleneoxyacrylate, nonylphenoxytetraethyleneoxyacrylate, nonylphenoxypentaethyleneoxyacrylate, nonylphenoxyhexaethyleneoxyacrylate, nonylphenoxyheptaethyleneoxyacrylate, nonylphenoxyoctaethyleneoxyacrylate Nonylphenoxynonaethyleneoxyacrylate, nonylphenoxydecaethyleneoxyacrylate, nonylphenoxyundecaethyleneoxyacrylate, and the like. These may be used alone or in any combination of two or more. “Nonylphenoxypolyethyleneoxyacrylate” is also referred to as “nonylphenoxypolyethyleneglycol acrylate”.

  Of these, nonylphenoxyoctaethyleneoxyacrylate is commercially available, for example, as M-114 (trade name, 4-normalnonylphenoxyoctaethyleneoxyacrylate, manufactured by Toagosei Co., Ltd.). Note that “4-normalnonylphenoxyoctaethyleneoxyacrylate” is also referred to as “4-normalnonylphenoxyoctaethylene glycol acrylate”.

  Examples of the phthalic acid compounds include γ-chloro-β-hydroxypropyl-β ′-(meth) acryloyloxyethyl-o-phthalate, β-hydroxyethyl-β ′-(meth) acryloyloxyethyl-o—. Phthalate, β-hydroxypropyl-β ′-(meth) acryloyloxyethyl-o-phthalate, and the like, among others, γ-chloro-β-hydroxypropyl-β ′-(meth) acryloyloxyethyl-o-phthalate Is preferred. γ-Chloro-β-hydroxypropyl-β'-methacryloyloxyethyl-o-phthalate is commercially available as FA-MECH (trade name, manufactured by Hitachi Chemical Co., Ltd.). These can be used alone or in combination of two or more.

  (B) When a component contains the photopolymerizable compound which has three or more ethylenically unsaturated bonds in a molecule | numerator, the content is a viewpoint which improves the resolution, adhesiveness, resist shape, and the peeling property after hardening in a well-balanced manner. Therefore, the content is preferably 5 to 50% by mass and more preferably 10 to 40% by mass with respect to the mass of the entire component (B).

  Examples of the compound having three or more ethylenically unsaturated bonds in the molecule include trimethylolpropane tri (meth) acrylate and EO-modified trimethylolpropane tri (meth) acrylate (one having a total number of repeating oxyethylene groups of 1 to 5). , PO-modified trimethylolpropane tri (meth) acrylate, EO, PO-modified trimethylolpropane tri (meth) acrylate, tetramethylolmethanetri (meth) acrylate, tetramethylolmethanetetra (meth) acrylate, dipentaerythritol penta (meth) Examples thereof include acrylate and dipentaerythritol hexa (meth) acrylate. These can be used alone or in combination of two or more. Among these, A-TMM-3 (manufactured by Shin-Nakamura Chemical Co., Ltd., trade name, tetramethylolmethane triacrylate), TMPT21E, TMPT30E (manufactured by Hitachi Chemical Co., Ltd., sample name) are available. EO-modified trimethylolpropane trimethacrylate) and the like.

  The total content of (B) component is preferably 30 to 70 parts by mass, more preferably 35 to 65 parts by mass with respect to 100 parts by mass of the total amount of component (A) and component (B). More preferably, it is 35-60 mass parts. In terms of excellent sensitivity and resolution, 30 parts by mass or more is preferable, and in terms of excellent resist shape, 70 parts by mass or less is preferable.

  Next, (C) the photopolymerization initiator will be described. The photosensitive resin composition of this invention is characterized by including the compound represented by following formula (1) as (C) photoinitiator.

式（１）中、Ｒ^１及びＲ^２は、それぞれ独立に下記式（１ａ）又は（１ｂ）で表される基を示す。

In formula (1), R ¹ and R ² each independently represent a group represented by the following formula (1a) or (1b).

式（１ａ）及び（１ｂ）中、Ｒは、それぞれ独立に炭素数１〜２０のアルキル基又はフェニル基を示し、反応性の観点から、炭素数１〜３のアルキル基又はフェニル基であることが好ましく、炭素数１〜３のアルキル基であることがより好ましい。複数存在するＲは同一でも異なっていてもよい。

In formulas (1a) and (1b), each R independently represents an alkyl group having 1 to 20 carbon atoms or a phenyl group, and is an alkyl group having 1 to 3 carbon atoms or a phenyl group from the viewpoint of reactivity. Is preferable, and an alkyl group having 1 to 3 carbon atoms is more preferable. A plurality of R may be the same or different.

  The compound represented by the above formula (1) can be represented by the following formula (1c).

  In the formula (1c), each X independently represents S (sulfur atom) or no bond (bonded to form no ring). Moreover, R shows a C1-C20 alkyl group or a phenyl group each independently, From a reactive viewpoint, a C1-C3 alkyl group or a phenyl group is preferable, and a C1-C3 alkyl group Is more preferable.

  The maximum absorption wavelength of the compound represented by the formula (1) is preferably in the range of 350 to 410 nm. As a result, good sensitivity can be obtained with respect to light having a wavelength of 350 to 410 nm, and at the same time, absorption on the long wavelength side of 500 nm or more is reduced, and stability under yellow light is improved.

  The content of the compound represented by the formula (1) is preferably 0.01 to 3 parts by mass with respect to 100 parts by mass of the total amount of the components (A) and (B), and 0.05 to 2 It is more preferable to set it as a mass part, It is still more preferable to set it as 0.05-1 mass part, It is especially preferable to set it as 0.05-0.5 mass part. By using the compound represented by the above formula (1), even if the content is 0.01 to 0.5 parts by mass with respect to 100 parts by mass of the total amount of the component (A) and the component (B), It is highly sensitive to direct drawing exposure with a wavelength of 405 nm, and resolution and adhesion can be improved.

  (C) The component may contain other photoinitiators other than the compound represented by Formula (1) to such an extent that the effect of this invention is not impaired. Examples of other photopolymerization initiators include benzophenone, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butanone-1,2-methyl-1- [4- (methylthio) phenyl]- Aromatic ketones such as 2-morpholino-propanone-1; benzyl derivatives such as benzyldimethyl ketal; 2- (o-chlorophenyl) -4,5-diphenylimidazole dimer, 2- (o-fluorophenyl) -4, 2,4,5-triarylimidazole dimers such as 5-diphenylimidazole dimer; acridine derivatives such as 9-phenylacridine, 1,7- (9,9′-acridinyl) heptane, and acylphosphine oxide derivatives Can be mentioned. These can be used alone or in combination of two or more.

  The content of the component (C) is preferably 0.01 to 10 parts by mass, and 0.05 to 5 parts by mass with respect to 100 parts by mass of the total amount of the components (A) and (B). More preferably, the content is 0.1 to 3 parts by mass. When the content of component (C) is less than 0.01 parts by mass, good sensitivity and resolution tend not to be obtained, and when it exceeds 10 parts by mass, a good shape tends to be difficult to obtain.

  The photosensitive resin composition of the present embodiment may further contain (D) a sensitizing dye and / or (E) a hydrogen donating compound for the purpose of further improving sensitivity.

  (D) Examples of the sensitizing dye include dialkylaminobenzophenones, pyrazolines, anthracene, coumarins, xanthones, oxazoles, benzoxazoles, thiazoles, benzothiazoles, triazoles, stilbenes, and triazines. , Thiophenes, naphthalimides and triarylamines. These are used alone or in combination of two or more.

  (D) The content of the sensitizing dye is preferably 0.01 to 10 parts by mass, and 0.05 to 5 parts by mass with respect to 100 parts by mass of the total amount of the components (A) and (B). More preferably, the content is 0.1 to 2 parts by mass. If the blending amount is less than 0.01 parts by mass, good sensitivity and resolution tend not to be obtained, and if it exceeds 10 parts by mass, a good shape tends to be difficult to obtain. Each is used alone or in combination of two or more.

  Examples of the (E) hydrogen donating compound include bis [4- (dimethylamino) phenyl] methane, bis [4- (diethylamino) phenyl] methane, leucocrystal violet, and N-phenylglycine.

  (E) The content of the hydrogen donor compound is preferably 0.01 to 10 parts by mass, and 0.05 to 5 parts by mass with respect to 100 parts by mass of the total amount of components (A) and (B). More preferably, it is 0.1 to 2 parts by mass. These may be used alone or in combination of two or more.

  If necessary, the photosensitive resin composition of the present embodiment includes a photopolymerizable compound (such as an oxetane compound) having at least one cationically polymerizable cyclic ether group in the molecule, a cationic polymerization initiator, malachite green, and the like. Dye, photochromic agent such as tribromophenylsulfone, leucocrystal violet, thermochromic inhibitor, plasticizer such as p-toluenesulfonamide, pigment, filler, antifoaming agent, flame retardant, stabilizer, adhesion promoter , Leveling agents, peeling accelerators, antioxidants, fragrances, imaging agents, thermal crosslinking agents, and the like. These are used alone or in combination of two or more. These contents are preferably about 0.01 to 20 parts by mass with respect to 100 parts by mass of the total amount of component (A) (binder polymer) and component (B) (photopolymerizable compound).

(Photosensitive resin composition solution)
The photosensitive resin composition of this embodiment can be dissolved in an organic solvent and used as a solution (coating liquid) of the photosensitive resin composition having a solid content of about 30 to 60% by mass. Examples of the organic solvent include methanol, ethanol, acetone, methyl ethyl ketone, methyl cellosolve, ethyl cellosolve, toluene, N, N-dimethylformamide, propylene glycol monomethyl ether, or a mixed solvent thereof.

  The said coating liquid is apply | coated on surfaces, such as a metal plate, and the photosensitive resin composition layer which consists of the photosensitive resin composition of this embodiment can be formed by making it dry. Examples of the metal plate include iron alloys such as copper, copper alloys, nickel, chromium, iron, and stainless steel, preferably copper, copper alloys, and iron alloys.

  The thickness of the photosensitive resin composition layer varies depending on its use, but is preferably about 1 to 100 μm after drying. You may coat | cover the surface on the opposite side to the metal plate of the photosensitive resin composition layer with a protective film. Examples of the protective film include polymer films such as polyethylene and polypropylene.

  The photosensitive resin composition layer of the present embodiment has not only excellent sensitivity, resolution, and adhesion, but also excellent plating formability and resist peeling property after plating, and has an effect of low contamination to plating.

(Photosensitive element)
Next, the photosensitive resin composition layer and photosensitive element according to this embodiment will be described. FIG. 1 is a schematic cross-sectional view showing an example of a photosensitive element. The photosensitive element 1 is a laminated body in which a support film 2, a photosensitive resin composition layer 3, and a protective film 4 in some cases are laminated in this order.

  The photosensitive resin composition layer 3 made of the photosensitive resin composition can be formed on the support film 2 by applying the solution of the photosensitive resin composition onto the support film 2 and drying it. Thus, the photosensitive element of this embodiment provided with the support film 2 and the said photosensitive resin composition layer 3 formed on this support film 2 is obtained.

  As the support film 2, a polymer film having heat resistance and solvent resistance such as polyester such as polyethylene terephthalate, polypropylene, and polyethylene can be used. The thickness of the support film (polymer film) is preferably 1 to 100 μm, more preferably 5 to 50 μm, and still more preferably 5 to 30 μm.

  Application of the photosensitive resin composition solution onto the support film 2 can be performed by a known method such as roll coating, comma coating, gravure coating, air knife coating, die coating, or bar coating.

  It is preferable to dry the solution of the photosensitive resin composition at 70 to 150 ° C. for about 5 to 30 minutes. After drying, the amount of the remaining organic solvent in the photosensitive resin composition layer 3 is preferably 2% by mass or less from the viewpoint of preventing diffusion of the organic solvent in the subsequent step.

  The thickness of the photosensitive resin composition layer 3 in the photosensitive element 1 varies depending on the use, but is preferably 1 to 100 μm, more preferably 1 to 50 μm, and more preferably 5 to 50 μm after drying. Is more preferable, and it is especially preferable that it is 10-40 micrometers. When this thickness is less than 1 μm, it tends to be difficult to apply industrially, and when it exceeds 100 μm, it tends to be difficult to obtain sufficient adhesion and resolution.

  The ultraviolet light transmittance with respect to the photosensitive resin composition layer 3 is preferably 5 to 75%, more preferably 10 to 65%, and more preferably 15 to 55% with respect to the ultraviolet light having a wavelength of 405 nm. Further preferred. If this transmittance is less than 5%, sufficient adhesion tends to be difficult to obtain, and if it exceeds 75%, sufficient resolution tends to be difficult to obtain. The transmittance can be measured with a UV spectrometer. An example of the UV spectrometer is a 228A type W beam spectrophotometer manufactured by Hitachi, Ltd.

  The photosensitive element 1 may be provided with the protective film 4 which coat | covers the surface on the opposite side to the support film 2 of the photosensitive resin composition layer 3 as needed.

  As the protective film 4, one having an adhesive force to the photosensitive resin composition layer 3 smaller than an adhesive force of the support film 2 to the photosensitive resin composition layer is preferable, and a film having a low fish eye is preferable. Here, “fish eye” means that when a material is heat-melted, kneaded, extruded, biaxially stretched, casting method, etc., foreign materials, undissolved materials, oxidatively deteriorated materials, etc. are present in the film. It means what was taken in. That is, “low fish eye” means that the above-mentioned foreign matter or the like in the film is small.

  Specifically, as the protective film 4, a polymer film having heat resistance and solvent resistance such as polyester such as polyethylene terephthalate, polypropylene, and polyethylene can be used. Commercially available products include polypropylene films such as Alphan MA-410 and E-200C manufactured by Oji Paper Co., Ltd., Shin-Etsu Film Co., Ltd., and PS series such as PS-25 manufactured by Teijin Limited. A terephthalate film etc. are mentioned. The protective film 4 may be the same as the support film.

  The thickness of the protective film 4 is preferably 1 to 100 μm, more preferably 5 to 50 μm, still more preferably 5 to 30 μm, and particularly preferably 15 to 30 μm. When the thickness is less than 1 μm, the protective film 4 tends to be broken when the photosensitive resin composition layer 2 and the protective film 4 are laminated (laminated) on the substrate. Tends to be insufficient.

  The photosensitive element may further include an intermediate layer such as a cushion layer, an adhesive layer, a light absorption layer, and a gas barrier layer.

  The obtained photosensitive element 1 can be stored in the form of a sheet or a roll wound around a core. When winding in roll form, it is preferable to wind up so that the support film 2 may become an outer side. Examples of the core include plastics such as polyethylene resin, polypropylene resin, polystyrene resin, polyvinyl chloride resin, and ABS resin (acrylonitrile-butadiene-styrene copolymer). An end face separator is preferably installed on the end face of the roll-shaped photosensitive element thus obtained from the viewpoint of protecting the end face, and a moisture-proof end face separator is preferably installed from the viewpoint of edge fusion resistance. As a packaging method, it is preferable to wrap and package in a black sheet with low moisture permeability.

(Method for forming resist pattern)
A resist pattern can be formed using the photosensitive resin composition. The resist pattern forming method according to the present embodiment includes (i) a lamination step of laminating a photosensitive resin composition layer composed of the photosensitive resin composition on a substrate, and (ii) a predetermined photosensitive resin composition layer. An exposure step of irradiating a portion with an actinic ray to expose and cure the predetermined portion; and (iii) removing a portion other than the predetermined portion of the photosensitive resin composition layer on the substrate, And a development step of forming a resist pattern made of a cured product of the photosensitive resin composition.

(I) Lamination process First, the photosensitive resin composition layer which consists of a photosensitive resin composition is laminated | stacked on a board | substrate. As the substrate, a substrate (circuit forming substrate) including an insulating layer and a conductor layer formed on the insulating layer can be used.

  Lamination of the photosensitive resin composition layer on the substrate is performed, for example, by removing the protective film of the photosensitive element and then pressing the photosensitive resin composition layer of the photosensitive element on the substrate while heating. Is called. Thereby, the laminated body which consists of a board | substrate, the photosensitive resin composition layer, and the support film, and these were laminated | stacked in order is obtained.

This lamination operation is preferably performed under reduced pressure from the viewpoint of adhesion and followability. The photosensitive resin composition layer and / or the substrate is preferably heated at a temperature of 70 to 130 ° C. at a pressure of about 0.1 to 1.0 MPa (about 1 to 10 kgf / cm ² ). Although pressure bonding is preferable, these conditions are not particularly limited. In addition, if the photosensitive resin composition layer is heated to 70 to 130 ° C., it is not necessary to pre-heat the substrate in advance, but the substrate can be pre-heated in order to further improve the stackability.

(Ii) Exposure Step Next, the predetermined portion of the photosensitive resin composition layer on the substrate is irradiated with actinic rays to expose and cure the predetermined portion. In this case, when the support film present on the photosensitive resin composition layer is transmissive to actinic rays, it can be irradiated with actinic rays through the support film, but the support film is light-shielding. In this case, after removing the support film, the photosensitive resin composition layer is irradiated with actinic rays.

  Examples of the exposure method include a method (mask exposure method) of irradiating an image with active light through a negative or positive mask pattern called an artwork. Alternatively, a method of irradiating actinic rays in the form of an image by a direct drawing exposure method such as an LDI (Laser Direct Imaging) exposure method or a DLP (Digital Light Processing) exposure method may be employed.

  As the actinic ray light source, a known light source can be used. For example, a carbon arc lamp, a mercury vapor arc lamp, a high pressure mercury lamp, a xenon lamp, a gas laser such as an argon laser, a solid laser such as a YAG laser, a semiconductor laser, etc. Those that effectively emit ultraviolet light, visible light, and the like are used.

  The wavelength of the actinic ray (exposure wavelength) is preferably in the range of 350 to 420 nm from the viewpoint of more reliably obtaining the effects of the present invention.

(Iii) Development Step Furthermore, a resist pattern made of a cured product of the photosensitive resin composition is formed on the substrate by removing portions other than the predetermined portion of the photosensitive resin composition layer from the substrate. When the support film is present on the photosensitive resin composition layer, the support film is removed, and then the portion (unexposed portion) other than the predetermined portion (exposed portion) is removed (developed). Development methods include wet development and dry development, but wet development is widely used.

  In the case of wet development, development is performed by a known development method using a developer corresponding to the photosensitive resin composition. Examples of the developing method include a method using a dip method, a battle method, a spray method, brushing, slapping, scraping, rocking immersion, and the like. From the viewpoint of improving the resolution, the high pressure spray method is most suitable. You may develop by combining these 2 or more types of methods.

  Examples of the developer include an alkaline aqueous solution, an aqueous developer, an organic solvent developer, and the like.

  The alkaline aqueous solution is safe and stable when used as a developer, and has good operability. Examples of the base of the alkaline aqueous solution include alkali hydroxides such as lithium, sodium, or potassium hydroxide; alkali carbonates such as lithium, sodium, potassium, or ammonium carbonate or bicarbonate; potassium phosphate, sodium phosphate, and the like. Alkali metal phosphates; alkali metal pyrophosphates such as sodium pyrophosphate and potassium pyrophosphate are used.

  As alkaline aqueous solution, 0.1-5 mass% dilute solution of sodium carbonate, 0.1-5 mass% dilute solution of potassium carbonate, 0.1-5 mass% dilute solution of sodium hydroxide, 0.1-5 A dilute solution of mass% sodium tetraborate is preferred. The pH of the alkaline aqueous solution is preferably in the range of 9 to 11, and the temperature is adjusted according to the alkali developability of the photosensitive resin composition layer. In the alkaline aqueous solution, a surfactant, an antifoaming agent, a small amount of an organic solvent for promoting development, and the like may be mixed.

  The aqueous developer is, for example, a developer composed of water or an alkaline aqueous solution and one or more organic solvents. Here, as the base of the alkaline aqueous solution, in addition to the substances described above, for example, borax, sodium metasilicate, tetramethylammonium hydroxide, ethanolamine, ethylenediamine, diethylenetriamine, 2-amino-2-hydroxymethyl-1 , 3-propanediol, 1,3-diaminopropanol-2, morpholine and the like. The pH of the aqueous developer is preferably as low as possible within a range where development is sufficiently performed, preferably pH 8 to 12, and more preferably pH 9 to 10.

  Examples of the organic solvent used in the aqueous developer include acetone, ethyl acetate, alkoxyethanol having an alkoxy group having 1 to 4 carbon atoms, ethyl alcohol, isopropyl alcohol, butyl alcohol, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether. Etc. These are used alone or in combination of two or more. In general, the concentration of the organic solvent in the aqueous developer is preferably 2 to 90% by mass, and the temperature can be adjusted according to alkali developability. A small amount of a surfactant, an antifoaming agent or the like can be mixed in the aqueous developer.

  Examples of the organic solvent developer include organic solvents such as 1,1,1-trichloroethane, N-methylpyrrolidone, N, N-dimethylformamide, cyclohexanone, methyl isobutyl ketone, and γ-butyrolactone. It is preferable to add water to these organic solvents in the range of 1 to 20% by mass in order to prevent ignition.

After removing the unexposed portion, the resist pattern may be further cured by heating at about 60 to 250 ° C. or exposure at about 0.2 to 10 J / cm ² as necessary.

(Printed wiring board manufacturing method)
A printed wiring board can be manufactured by etching or plating a substrate on which a resist pattern is formed by the above method. Etching or plating of the substrate is performed on the conductor layer of the substrate using the formed resist pattern as a mask.

  Etching solutions used for etching include cupric chloride solution, ferric chloride solution, alkaline etching solution, and hydrogen peroxide etching solution. It is preferable to use an iron solution.

  The plating methods for plating include copper plating such as copper sulfate plating and copper pyrophosphate plating, solder plating such as high-throw solder plating, watt bath (nickel sulfate-nickel chloride) plating, nickel plating such as nickel sulfamate, Gold plating such as hard gold plating and soft gold plating can be used.

  After the etching or plating is completed, the resist pattern can be peeled off with a stronger alkaline aqueous solution than the alkaline aqueous solution used for development, for example. As this strongly alkaline aqueous solution, for example, a 1 to 10% by mass sodium hydroxide aqueous solution, a 1 to 10% by mass potassium hydroxide aqueous solution, an amine stripper and the like are used. Of these, an amine stripper is preferable.

  Examples of the resist pattern peeling method include an immersion method and a spray method, which may be used alone or in combination. The printed wiring board on which the resist pattern is formed may be a multilayer printed wiring board or may have a small diameter through hole.

  The preferred embodiment of the present invention has been described above, but the present invention is not limited to the above embodiment.

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

(Examples 1-10 and Comparative Examples 1-3)
(Preparation of solution of photosensitive resin composition)
By mixing the components shown in Table 1 below in the blending amounts shown in the same table, solutions of the photosensitive resin compositions of Examples 1 to 10 and Comparative Examples 1 to 3 were prepared. In addition, the compounding quantity of (A) component shown in Table 1 and Table 2 is the mass (solid content) of a non volatile matter. Details of each component shown in the following Tables 1 and 2 are as follows.

<(A) Binder polymer>
[Synthesis of Binder Polymer (A-1)]
A polymerizable monomer (monomer) of 150 g of methacrylic acid, 125 g of benzyl methacrylate, 25 g of methyl methacrylate and 200 g of styrene (mass ratio 30/25/5/40), and 9.0 g of azobisisobutyronitrile. The solution obtained by mixing was designated as “Solution a”.

  A solution obtained by dissolving 1.2 g of azobisisobutyronitrile in 100 g of a mixed solution (mass ratio 3: 2) of 60 g of methyl cellosolve and 40 g of toluene was designated as “Solution b”.

  Into a flask equipped with a stirrer, reflux condenser, thermometer, dropping funnel and nitrogen gas introduction tube, 450 g of a mixed solution of 270 g of methyl cellosolve and 180 g of toluene (mass ratio 3: 2) was charged, and nitrogen gas was introduced into the flask. While stirring, the mixture was stirred and heated to 80 ° C.

  The solution a was added dropwise to the mixed solution in the flask over 4 hours, and then kept at 80 ° C. for 2 hours with stirring. Next, the solution b was added dropwise to the solution in the flask over 10 minutes, and then the solution in the flask was kept at 80 ° C. for 3 hours while stirring. Further, the temperature of the solution in the flask was raised to 90 ° C. over 30 minutes, kept at 90 ° C. for 2 hours, and then cooled to obtain a solution of binder polymer (A-1).

The binder polymer (A-1) had a non-volatile content (solid content) of 47.8% by mass, a weight average molecular weight of 30000, and an acid value of 196 mgKOH / g. The weight average molecular weight was measured by gel permeation chromatography (GPC) and derived by conversion using a standard polystyrene calibration curve. The GPC conditions are shown below.
(GPC conditions)
Pump: Hitachi L-6000 type [manufactured by Hitachi, Ltd.]
Column: Gelpack GL-R420 + Gelpack GL-R430 + Gelpack GL-R440 (3 in total) (above, manufactured by Hitachi Chemical Co., Ltd., trade name)
Eluent: Tetrahydrofuran Measurement temperature: 40 ° C
Flow rate: 2.05 mL / min Detector: Hitachi L-3300 type RI (manufactured by Hitachi, Ltd.)

<(B) Photopolymerizable compound>
TMPT21E: Trimethylolpropane polyoxyethylene ether trimethacrylate (trade name, manufactured by Hitachi Chemical Co., Ltd.)
FA-321M: 2,2-bis (4- (methacryloxypentaethoxy) phenyl) propane) (manufactured by Hitachi Chemical Co., Ltd., trade name)
FA-024M: Compound represented by the above formula (4), wherein R ⁷ and R ⁸ = methyl group, r ³ = 6 (average value), s ² + s ³ = 12 (average value) (Hitachi) Kasei Kogyo Co., Ltd., trade name)
BPE-200: 2,2-bis (4- (methacryloxypolyethoxy) phenyl) propane) (4 moles of ethylene oxide chain contained in one molecule) (trade name, manufactured by Shin-Nakamura Chemical Co., Ltd.)
M-114: 4-normal nonylphenoxy octaethylene glycol acrylate (trade name, manufactured by Toagosei Co., Ltd.)

<Photopolymerization initiator (C)>
[Photoinitiator (C-1): Synthesis of OXE-TPABP]
To the flask, 4.14 g (0.17 mol) of sodium hydride and 150 mL of anhydrous DMF were added, stirred at room temperature for 30 minutes under a nitrogen atmosphere, 33.98 g (0.20 mol) of diphenylamine was added, and then bis (4-fluoro Phenyl) methanone (15.27 g, 0.07 mol) was added, and the mixture was stirred at 150 ° C. for 12 hours. Thereafter, water was poured into the reaction solution, and the reaction product was filtered by suction filtration. Recrystallization from ethanol gave a yellow solid A.

  Next, the solid A4 obtained while cooling in an ice bath to a solution obtained by adding 13.87 g (20 mmol) of aluminum chloride, 2.95 mL (41.6 mmol) of acetyl chloride and 60 mL of dichloromethane to a 200 mL flask under a nitrogen atmosphere. A solution of 2 g (8 mmol) dissolved in 40 mL of dichloromethane was added dropwise. After completion of the dropwise addition, the reaction was continued for 1 hour in an ice bath and 7 hours in the air, the reaction product was poured into ice water, and the organic layer was taken out with a separatory funnel. The organic layer was washed with water three times, the solvent was distilled off with a rotary evaporator, and then dried overnight in a vacuum dryer (60 ° C.) to obtain a product B.

  Dissolve 1.0 g (1.5 mmol) of product B in 30 mL of N, N-dimethylacetamide, add 0.834 g (12 mmol) of hydroxylamine hydrochloride and 1.132 g (13.8 mmol) of sodium acetate, Stir for hours. Next, the reaction product was poured into water, and the precipitate was isolated by filtration and then dried in a vacuum dryer to obtain product C.

  To a solution of product C dissolved in chloroform / dichloromethane = 1/1 solution (40 mL), 1.0 mL (10.8 mmol) of acetic anhydride was added dropwise over 30 minutes, followed by reaction for 7 hours. The reaction solution was neutralized with 5 mL of 5% by mass aqueous sodium hydroxide solution, washed 3 times with water, and the organic layer was dried over anhydrous magnesium sulfate. Subsequently, the organic layer was separated by filtration, the solvent was distilled off with a rotary evaporator, and then recrystallized with ethanol to obtain the desired product (C-1): OXE-TPABP.

  From the 1H-NMR spectrum shown in FIG. 2, it was confirmed that the product (C-1) was a compound having a structure represented by the following formula.

[Photoinitiator (C-2): Synthesis of OXE-TPSBP]
In the synthesis of the photopolymerization initiator (C-1), a compound (C) having the structure represented by the following formula is used in the same manner as the synthesis of (C-1) except that phenothiazine is used instead of diphenylamine. -2) was obtained.

[Synthesis of Photopolymerization Initiator (C-3)]
In the synthesis of the photopolymerization initiator (C-1), except that 4-fluorobenzophenone was used instead of bis (4-fluorophenyl) methanone, the following formula was used. The compound (C-3) which has a structure represented by this was obtained.

[Synthesis of Photopolymerization Initiator (C-4)]
In the synthesis of the photopolymerization initiator (C-1), 4-fluorobenzophenone was used instead of bis (4-fluorophenyl) methanone, and phenothiazine was used instead of diphenylamine. In the same manner as above, a compound (C-4) having a structure represented by the following formula was obtained.

[Other photopolymerization initiators]
BCIM: 2,2′-bis (2-chlorophenyl) -4,4 ′, 5,5′-tetraphenylbisimidazole (product name, manufactured by Hampton)

<(D) Sensitizing dye>
Nikka Flow MC: (Nippon Chemical Industry Co., Ltd .: 7-diethylamino-4-methylcoumarin)
<(E) Hydrogen donating compound>
LCV: leuco crystal violet (manufactured by Yamada Chemical Co., Ltd., trade name)
MBO: 2-mercaptobenzoxazole NPG: N-phenylglycine

(Photosensitive element)
The above photosensitive resin composition solution was uniformly applied onto a polyethylene terephthalate film (trade name “HTF-01” manufactured by Teijin Ltd.) having a thickness of 16 μm, and hot air convection drying at 70 ° C. and 110 ° C. The photosensitive resin composition layer whose film thickness after drying was 40 micrometers was formed with the container. A protective film (manufactured by Tamapoly Co., Ltd., trade name “NF-15”) is laminated on the photosensitive resin composition layer, and a polyethylene terephthalate film (support film), the photosensitive resin composition layer, and a protective film A photosensitive element in which was stacked in order was obtained.

(Laminated substrate)
The copper surface of a copper-clad laminate (made by Hitachi Chemical Co., Ltd., trade name “MCL-E-67”) composed of a glass epoxy material and copper foil (thickness 35 μm) formed on both sides thereof is Polishing was performed using a polishing machine (manufactured by Sankei Co., Ltd.) having a brush equivalent to 600, washed with water, and then dried with an air stream. After heating this copper clad laminated board (henceforth "a board | substrate") and heating up at 80 degreeC, the photosensitive element which concerns on Examples 1-10 and Comparative Examples 1-3 is applied to the copper surface of a board | substrate. Laminated. Lamination was performed under the conditions of a temperature of 120 ° C. and a lamination pressure of 4 kgf / cm ² so that the photosensitive resin composition layer of each photosensitive element was in close contact with the copper surface of the substrate while removing the protective film. Thus, the laminated substrate by which the photosensitive resin composition layer and the polyethylene terephthalate film were laminated | stacked on the copper surface of the board | substrate was obtained.

(Evaluation of sensitivity)
The obtained laminated substrate was allowed to cool and when the temperature reached 23 ° C., on the polyethylene terephthalate film of the laminated substrate, a concentration region of 0.00 to 2.00, a concentration step of 0.05, and a tablet size of 20 mm × 187 mm. A photo tool having a 41-step tablet having a size of 3 mm × 12 mm for each step was brought into close contact. Using a direct drawing machine “DE-1AH” (trade name) manufactured by Hitachi Via Mechanics Co., Ltd. with a blue-violet laser diode having a wavelength of 405 nm as a light source, a photo tool and a polyethylene terephthalate film with a predetermined energy amount (exposure amount) Then, the photosensitive resin composition layer was exposed to light. The illuminance was measured using an ultraviolet illuminometer (trade name “UIT-150” manufactured by USHIO INC.) Using a 405 nm probe.

After the exposure, the polyethylene terephthalate film was peeled from the laminated substrate, the photosensitive resin composition layer was exposed, and a 1% by mass aqueous sodium carbonate solution was sprayed at 30 ° C. for 60 seconds to remove unexposed portions. Thus, the cured film which consists of hardened | cured material of the photosensitive resin composition was formed on the copper surface of a board | substrate. The sensitivity of the photosensitive resin composition was evaluated by the exposure amount (mJ / cm ² ) when the number of remaining steps of the step tablet obtained as a cured film was 20. The smaller this value, the better the sensitivity. The results are shown in Tables 3 and 4.

(Evaluation of resolution and adhesion)
The remaining 41-step tablet using a drawing pattern having a line width (L) / space width (S) (hereinafter referred to as “L / S”) of 5/5 to 30/30 (unit: μm) Exposure (drawing) was performed on the photosensitive resin composition layer of the multilayer substrate with an energy amount of 20 steps. After the exposure, the same development processing as in the sensitivity evaluation was performed.

  After development, the space part (unexposed part) is removed cleanly, and the line part (exposed part) has a resolution that is the smallest line width / space width value among the resist patterns formed without meandering or chipping. And the adhesion was evaluated. A smaller value means better resolution and adhesion. The results are shown in Tables 3 and 4.

(Evaluation of peeling properties)
After exposing the obtained multilayer substrate with an energy amount that the remaining number of steps of the 41-step tablet is 20 steps, the polyethylene terephthalate film is peeled off from the laminate substrate to expose the photosensitive resin composition layer, By performing spray development using a 1% by mass aqueous sodium carbonate solution, a test piece (40 mm × 50 mm) having a cured film formed on the substrate was produced. After leaving this test piece for a whole day and night at room temperature, it peeled off using 3 mass% sodium hydroxide aqueous solution of 50 degreeC. The time from the start of stirring until the cured film was completely peeled and removed from the substrate was defined as the peeling time. Moreover, the size of the peeling piece after peeling was observed visually, and the following references | standards evaluated. The shorter the peeling time and the smaller the peeling piece size, the better the peeling characteristics. The results are shown in Tables 3 and 4.

(Evaluation of plating formability)
The test piece after peeling obtained by the evaluation of the peeling characteristics was observed using an optical microscope, and the plating formability was evaluated by the smallest plating width formed without disconnection or short circuit of the plating pattern. A smaller value means better plating formability. The results are shown in Tables 3 and 4.

(Evaluation of plating contamination)
Each photosensitive element is cut into a size of 40 mm x 50 mm, the protective film is removed, and the photosensitive resin composition layer is exposed with an exposure amount that makes the step tablet 20 steps, and the polyethylene terephthalate film is peeled off and cured. A membrane was obtained. The cured film was immersed in a copper sulfate / sulfuric acid aqueous plating solution for 3 days, and then the copper-clad laminate (substrate) was subjected to electrolytic copper plating using a Hull Cell test bath (manufactured by Yamamoto Metal Tester Co., Ltd.). The plating appearance of the substrate in the case of using the plating solution in which the cured film was immersed was visually observed using the plating solution in which the cured film was not immersed as a reference. The case where there was no difference in plating appearance compared to the reference was judged as no contamination, and the case where there was a difference was judged as contamination. The results are shown in Tables 3 and 4.

  The photosensitive resin compositions of Examples 1 to 10 are highly sensitive to direct drawing exposure at a wavelength of 405 nm, have excellent resolution, adhesion, peeling properties and plating formability, and can prevent plating contamination. confirmed. In contrast, the photosensitive resin compositions of Comparative Examples 1 to 3 were inferior to the photosensitive resin compositions of Examples 1 to 10 in terms of resolution, adhesion, and plating formability. Moreover, the sensitivity of the photosensitive resin compositions of Comparative Examples 2 and 3 was not sufficient.

  ADVANTAGE OF THE INVENTION According to this invention, the photosensitive resin composition excellent in a sensitivity, resolution, and adhesiveness, the photosensitive element using the same, the formation method of a resist pattern, and the manufacturing method of a printed wiring board can be provided.

  DESCRIPTION OF SYMBOLS 1 ... Photosensitive element, 2 ... Support film, 3 ... Photosensitive resin composition layer, 4 ... Protective film.

Claims (6)

(A) A photosensitive resin composition containing a binder polymer, (B) a photopolymerizable compound, and (C) a photopolymerization initiator, wherein the (C) photopolymerization initiator is represented by the following formula (1) The photosensitive resin composition containing the compound represented by this.

[In formula (I), R ¹ and R ² each independently represent a group represented by the following formula (1a) or (1b). ]

[In formulas (1a) and (1b), R independently represents an alkyl group having 1 to 20 carbon atoms or a phenyl group, and a plurality of R may be the same or different. ]   The photosensitive resin composition according to claim 1, wherein the maximum absorption wavelength of the compound represented by the formula (1) is within a range of 350 to 410 nm.   The photosensitive resin composition according to claim 1 or 2, wherein the (A) binder polymer contains (meth) acrylic acid and styrene or a styrene derivative as a copolymerization component.   A photosensitive element provided with a support body and the photosensitive resin composition layer which consists of the photosensitive resin composition as described in any one of Claims 1-3 formed on this support body. A laminating step of laminating a photosensitive resin composition layer comprising the photosensitive resin composition according to any one of claims 1 to 3 on a substrate;
An exposure step of irradiating a predetermined portion of the photosensitive resin composition layer with an actinic ray;
A developing step of forming a resist pattern made of a cured product of the photosensitive resin composition on the substrate by removing portions other than the predetermined portion of the photosensitive resin composition layer from the substrate;
A resist pattern forming method including:   The manufacturing method of a printed wiring board including the process of etching or plating the board | substrate with which the resist pattern was formed by the method of Claim 5.

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