WO2023284643A1

WO2023284643A1 - Photosensitive composition, photosensitive element, and method of producing wiring board

Info

Publication number: WO2023284643A1
Application number: PCT/CN2022/104595
Authority: WO
Inventors: Akitoshi Tanimoto; Sadaaki Kato; Yasuharu Murakami; Masaru Yamasaki; Minoru Hoshino; Xuesong Jiang; Xiao-dong MA
Original assignee: Showa Denko Materials Co., Ltd.; Shanghai Jiao Tong University
Priority date: 2021-07-16
Filing date: 2022-07-08
Publication date: 2023-01-19
Also published as: CN117693714A; WO2023283915A1; TW202309656A; KR20240035832A

Abstract

A photosensitive composition containing: a photopolymerizable compound; a hexaarylbiimidazole compound; and a compound represented by the following formula (1) wherein R ¹, R ² and R ³ each independently represent an alkyl group having 5 or less carbon atoms, R ⁴ represents a halogen atom, an alkyl group or an alkoxy group, and m and n each independently represent an integer of 0 or more.

Description

PHOTOSENSITIVE COMPOSITION, PHOTOSENSITIVE ELEMENT, AND METHOD OF PRODUCING WIRING BOARD

Cross Reference of Related Application

The present application claims a priority of the PCT Application PCT/CN2021/106686 filed on July 16, 2021, which is incorporated herein by reference in its entirety.

Technical Field

The present disclosure relates to a photosensitive composition, a photosensitive element, and a method of producing a wiring board.

Background Art

In wiring board production, a resist pattern is formed for obtaining a desired wiring pattern. Photosensitive compositions are widely used in resist patterning. In recent years, MSAP (Modified Semi Additive Process) has received attention as a promising method for forming a fine wiring pattern. It is required that a resist pattern is formed with a high accuracy compared to conventional methods to obtain a fine wiring pattern by this method.

A photosensitizer is typically used in the photosensitive composition in addition to a photopolymerizable compound and a photopolymerization initiator. In such a photosensitive composition, for example, a hexaarylbiimidazole compound is used as the photopolymerization initiator. For example, 9, 10-dibutoxyanthracene (DBA) is known as the photosensitizer (see Patent Document 1, for example) .

Citation List

Patent Literature

[Patent Document 1] WO 2007/123062

Summary of Invention

Technical Problem

According to the investigation by the present inventors, when the hexaarylbiimidazole compound is used as the photopolymerization initiator as in Patent Document 1, there is room for further investigation in selecting the photosensitizer. Specifically, the photosensitive composition is usually used in the form of a photosensitive element sandwiched between polymer films, and according to the investigation by the present inventors, when the photosensitive composition contains DBA in addition to the hexaarylbiimidazole compound, DBA migrates to the polymer film, and a problem (migration) that a desired pattern shape cannot be formed during resist pattern formation may occur. This problem occurs especially when the polymer films are polyethylene films.

An object of one aspect of the present invention is to provide a photosensitive composition capable of suppressing the migration of a photosensitizer into a polyethylene film.

Solution to Problem

The present inventors have found that by selecting a specific compound as a photosensitizer to be used together with a hexaarylbiimidazole compound, the migration of the photosensitizer into a polyethylene film can be suppressed as compared with the case of using DBA as the photosensitizer.

The present invention includes the following aspects:

[1] A photosensitive composition comprising: a photopolymerizable compound; a hexaarylbiimidazole compound; and a compound represented by the following formula (1) :

wherein R ¹, R ² and R ³ each independently represent an alkyl group having 5 or less carbon atoms, R ⁴ represents a halogen atom, an alkyl group or an alkoxy group, and m and n each independently represent an integer of 0 or more.

[2] The photosensitive composition according to [1] , wherein the alkyl group represented by R ¹, R ² and R ³ in the formula (1) has 2 or more carbon atoms.

[3] The photosensitive composition according to [1] or [2] , wherein m and n are 0 in the formula (1) .

[4] The photosensitive composition according to [1] or [2] , wherein m is 1 and n is 0 in the formula (1) .

[5] The photosensitive composition according to [1] or [2] , wherein m is 0 and n is 1 in the formula (1) .

[6] The photosensitive composition according to [1] or [2] , wherein m is 0 and n is 2 in the formula (1) .

[7] The photosensitive composition according to [1] or [2] , wherein the compound represented by the formula (1) is a compound represented by the following formula (6) :

wherein R ¹ and R ² have the same meanings as R ¹ and R ² in Formula (1) , respectively, and R ⁴ represents a halogen atom.

[8] The photosensitive composition according to [7] , wherein the halogen atom is chlorine atom.

[9] A photosensitive element comprising: a support; and a photosensitive layer disposed on the support, the photosensitive layer comprising the photosensitive composition according to any one of [1] to [8] .

[10] A method of producing a wiring board, comprising:

disposing a photosensitive layer comprising the photosensitive composition according to any one of [1] to [8] on a substrate; photocuring a part of the photosensitive layer; removing an uncured part of the photosensitive layer to form a resist pattern; and forming a wiring layer on a part of the substrate on which no resist pattern is formed.

Advantageous Effects of Invention

The present invention can provide a photosensitive composition capable of suppressing the migration of a photosensitizer into a polyethylene film. Another aspect of the present invention can provide a photosensitive composition having excellent sensitivity (in particular, sensitivity in the case of using a low-illuminance light source) . Another aspect of the present invention can provide a photosensitive composition having excellent adhesiveness to a substrate.

Brief Description of Drawings

Fig. 1 is a schematic sectional view of a photosensitive element according to an embodiment.

Fig. 2 is a scheme view of a method of producing a wiring board according to an embodiment.

Description of Embodiments

Embodiments of the present invention will be described below in detail. The term “step” in the present specification refers to an independent step; as well as a step that successfully achieves the intended action of the step and is not clearly differentiated from other steps. A numerical range specified using the word “to” refers to a range that includes the numerical values preceding and following the word “to” as the minimum and the maximum values of the range. The term “layer” refers to a structure that is formed all over the surface of something in a plan view as well as a structure that is formed on a partial surface of something in a plan view. The term “ (meth) acrylic acid” refers to at least one of “acrylic acid” and corresponding “methacrylic acid” . The same applies to other similar expressions such as (meth) acryloyl group.

In the present specification, a content of each component in a composition in the present specification, when there are a plurality of substances contained in the composition that consist the component, refers to the total content of all of these substances in the composition unless otherwise indicated. In the present specification, the term “solid component” refers to nonvolatile component in a photosensitive composition, not including volatile substances (water or solvent, for example) . More specifically, the term “solid component” refers to any component that is not solvent and that does not volatilize but remains after drying a photosensitive composition which is described below, and includes a substance that is in a liquid state, a syrup-like state, or a wax state at room temperature (25℃) .

One embodiment of the present invention is a photosensitive composition containing a photopolymerizable compound, a hexaarylbiimidazole compound, and a compound represented by the following formula (1) :

wherein R ¹, R ² and R ³ each independently represent an alkyl having 5 or less carbon atoms, R ⁴ represents a halogen atom, an alkyl or alkoxy group, and m and n each independently represent an integer of 0 or more.

The photosensitive composition contains one or two or more photopolymerizable compounds. The photopolymerizable compound may be a compound that is polymerized by light, and may be, for example, a compound having an ethylenically unsaturated bond and may be a compound having a (meth) acryloyl group.

The photopolymerizable compound may contain a bisphenol A (meth) acrylate compound from the viewpoint of further improvement in alkaline development properties, resolution, and post-curing peeling properties. Examples of the bisphenol A (meth) acrylate compound include 2, 2-bis (4- ( (meth) acryloxypolyethoxy) phenyl) propane (such as 2, 2-bis (4- ( (meth) acryloxypentaethoxy) phenyl) propane) , 2, 2-bis (4- ( (meth) acryloxypolypropoxy) phenyl) propane, 2, 2-bis (4- ( (meth) acryloxypolybutoxy) phenyl) propane, and 2, 2-bis (4- ( (meth) acryloxypolyethoxypolypropoxy) phenyl) propane. The photopolymerizable compound may contain 2, 2-bis (4- ( (meth) acryloxypolyethoxy) phenyl) propane (such as 2, 2-bis (4- ( (meth) acryloxypentaethoxy) phenyl) propane) from the viewpoint of further improvement in resolution and peeling properties.

The content of the bisphenol A (meth) acrylate compound based on the total content of the photopolymerizable compound may be 20%by mass or more or 40%by mass or more and may be 100%by mass or less, 95%by mass or less, or 90%by mass or less from the viewpoint of further improvement in resist patterning resolution.

The photopolymerizable compound may contain an α, β-unsaturated ester compound obtained by reaction between a polyhydric alcohol and an α, β-unsaturated carboxylic acid from the viewpoint of further proper improvement in resolution and flexibility. Examples of the α, β-unsaturated ester compound include polyalkylene glycol di (meth) acrylates such as polyethylene glycol di (meth) acrylate, polypropylene glycol di (meth) acrylate, and EO-modified polypropylene glycol, trimethylolpropane di (meth) acrylate, trimethylolpropane tri (meth) acrylate, EO-modified trimethylolpropane tri (meth) acrylate, PO-modified trimethylolpropane tri (meth) acrylate, EO·PO-modified trimethylolpropane tri (meth) acrylate, tetramethylolmethane tri (meth) acrylate, and tetramethylolmethane tetra (meth) acrylate.

The content of the α, β-unsaturated ester compound based on the total content of the photopolymerizable compound may be 20%by mass or more or 30%by mass or more from the viewpoint of improvement in flexibility, and may be 70%by mass or less or 60%by mass or less from the viewpoint of further improvement in resolution.

The photopolymerizable compound may include a phthalic acid ester compound, an alkyl (meth) acrylate, nonylphenoxy-polyethyleneoxy-acrylate, a photopolymerizable compound having at least one cationically polymerizable cyclic ether group in the molecule (oxetane compound and the like) , and the like. The photopolymerizable compound may contain a phthalic acid-based compound from the viewpoint of further suitably improving the resolution, adhesion, resist shape, and release characteristics after curing.

The phthalic ester compound may be, for example, a compound having a phthalic acid structure and a (meth) acryloyl group. Such compounds may be, for example, γ-chloro-β-hydroxypropyl-β’- (meth) acryloyloxyethyl-o-phthalate (also called 3-chloro-2-hydroxypropyl-2- (meth) acryloyloxyethylphthalate) , β-hydroxyethyl-β’- (meth) acryloyloxyethyl-o-phthalate, or β-hydroxypropyl-β’- (meth) acryloyloxyethyl-o-phthalate, preferably γ-chloro-β-hydroxypropyl-β’- (meth) acryloyloxyethyl-o-phthalate.

When the photopolymerizable compound contains the phthalic ester compound, the content of the phthalic ester compound based on the total content of the photopolymerizable compound may be 1%by mass or more, 3%by mass or more, or 5%by mass or more and 30%by mass or less, 25%by mass or less, or 20%by mass or less, from the viewpoint of further proper improvement in resolution, adhesion, resist shape, and post-curing peeling properties.

The content of the photopolymerizable compound based on the total content of solid component in the photosensitive composition may be 3%by mass or more, 10%by mass or more, or 25%by mass or more from the viewpoint of further improvement in sensitivity and resolution, and may be 70%by mass or less, 60%by mass or less, or 50%by mass or less from the viewpoint of excellent film formation.

The hexaarylbiimidazole compound is a compound capable of functioning as a photopolymerization initiator. The hexaarylbiimidazole compound has a structure represented by the following formula (A) :

wherein Aryl represents an aryl group. The six aryl groups may be the same as or different from each other.

The aryl group may be, for example, a substituted or unsubstituted phenyl group. The substituted phenyl group may be, for example, a group in which one or two or more of the hydrogen atoms in the phenyl group are substituted with a halogen atom, an alkyl group, or an alkoxy group. The halogen atom may be, for example, chlorine atom. The number of carbon atoms of the alkyl group, for example, may be 1 or more, and may be 4 or less. The alkyl group may be, for example, methyl group. The number of carbon atoms of the alkoxy group, for example, may be 1 or more, and may be 4 or less. The alkoxy group may be, for example, methoxy group.

The hexaarylbiimidazole compound may be, for example, 2, 2’-bis (2-chlorophenyl) -4, 4’, 5, 5’-tetraphenyl-1, 2’-biimidazole, 2, 2’-bis (4-methoxyphenyl) -4, 4’, 5, 5’-tetraphenyl-1, 2’-biimidazole and the like, and is preferably 2, 2’-bis (2-chlorophenyl) -4, 4’, 5, 5’-tetraphenyl-1, 2’-biimidazole.

The content of the hexaarylbiimidazole compound may be 0.1%by mass or more, 0.5%by mass or more, or 1%by mass or more, and may be 20%by mass or less, 10%by mass or less, or 5%by mass or less, based on the total solid content of the photosensitive composition, from the viewpoint of further improving sensitivity and adhesiveness.

The compound represented by the above formula (1) is a compound capable of functioning as a photosensitizer. In the above formula (1) , the alkyl group represented by R ¹, R ² and R ³ may be linear or branched. The number of carbon atoms of the alkyl group may be 1 or more or 2 or more, and may be 4 or less or 3 or less, or may be 2. When m is an integer of 2 or more, a plurality of R ³s may be the same as or different from each other.

In the formula (1) , the halogen atom represented by R ⁴ may be, for example, chlorine atom or bromine atom. The alkyl group represented by R ⁴ may be linear or branched. The number of carbon atoms of the alkyl group may be 1 or more, may be 5 or less, 4 or less, 3 or less, or 2 or less, and may be or 1 or 2. The alkoxy group represented by R ⁴ may be linear or branched. The number of carbon atoms of the alkoxy group may be 1 or more and may be 5 or less. When n is an integer of 2 or more, a plurality of R ⁴s may be the same as or different from each other. R ⁴ is preferably halogen atom, and more preferably chlorine atom, from the viewpoint of increasing the sensitivity of the photosensitive composition to both a low-illuminance light source and a high-illuminance light source.

In the formula (1) , m may be an integer of 1 or more, and may be an integer of 3 or less, 2 or less, or 1 or less. n may be an integer of 1 or more, and may be an integer of 3 or less or 2 or less.

In an embodiment, m and n may be 0. That is, in one embodiment, the compound represented by the formula (1) may be a compound represented by the following formula (2) :

wherein R ¹ and R ² have the same meanings as R ¹and R ² in the formula (1) , respectively.

In an embodiment, m may be 1 and n may be 0. That is, in one embodiment, the compound represented by the formula (1) may be a compound represented by the following formula (3) and may be a compound represented by the following formula (4) :

wherein R ¹, R ² and R ³ have the same meanings as R ¹, R ² and R ³ in the formula (1) , respectively.

In an embodiment, m may be 0 and n may be 1. That is, in one embodiment, the compound represented by the formula (1) may be a compound represented by the following formula (5) and may be a compound represented by the following formula (6) :

wherein R ¹, R ² and R ⁴ have the same meanings as R ¹, R ² and R ⁴ in the formula (1) , respectively.

In an embodiment, m may be 0 and n may be 2. That is, in one embodiment, the compound represented by the formula (1) may be a compound represented by the following formula (7) and may be a compound represented by the following formula (8) :

The content of the compound represented by formula (1) may be, for example, 0.01%by mass or more, preferably 0.05%by mass or more, more preferably 0.1%by mass or more, and even more preferably 0.3%by mass or more, based on the total solid content of the photosensitive composition, from the viewpoint of further improving sensitivity. The content of the compound represented by the formula (1) is, for example, 10%by mass or less, preferably 5%by mass or less, more preferably 3%by mass or less, still more preferably 2%by mass or less, and particularly preferably 1%by mass or less, based on the total solid content of the photosensitive composition, from the viewpoint of further improving the accuracy of pattern formation.

The photosensitive composition may further contain a resin (binder resin) . The resin may be an alkali-soluble resin from the viewpoint that development with an alkali can be suitably performed.

Examples of the resin include acrylic resins. The acrylic resin may contain, for example, (meth) acrylic acid as a monomer unit, and may further contain a (meth) acrylic acid ester. Examples of the (meth) acrylic acid esters include alkyl (meth) acrylates, cycloalkyl (meth) acrylates, and aryl (meth) acrylates.

The acrylic resin may further contain styrene or a styrene derivative as a monomer unit from the viewpoint of further improving resolution and adhesiveness. The styrene derivative may be, for example, vinyltoluene, α-methylstyrene, and the like. The acrylic resin preferably contains (meth) acrylic acid, a (meth) acrylic acid ester, and styrene or a styrene derivative as monomer units.

The content of (meth) acrylic acid may be, for example, 5%by mass or more, 10%by mass or more, or 20%by mass or more, and may be 80%by mass or less, 60%by mass or less, or 50%by mass or less, based on the total amount of monomer units constituting the acrylic resin. The content of the (meth) acrylic acid ester may be, for example, 5%by mass or more, 10%by mass or more, or 20%by mass or more, and may be 80%by mass or less, 60%by mass or less, or 50%by mass or less, based on the total amount of the monomer units constituting the acrylic resin. The content of styrene and the styrene derivative may be, for example, 5%by mass or more, 10%by mass or more, or 20%by mass or more, and may be 65%by mass or less, 55%by mass or less, or 50%by mass or less, based on the total amount of the monomer units constituting the acrylic resin.

The acid value of the resin may be 100 mgKOH/g or more, 120 mgKOH/g or more, 140 mgKOH/g or more, or 150 mgKOH/g or more from the viewpoint of favorable developability, and may be 250 mgKOH/g or less, 240 mgKOH/g or less, or 230 mgKOH/g or less from the viewpoint of improving the adhesiveness (developer resistance) of the cured product of the photosensitive composition. The acid value of the resin can be adjusted by the content of the monomer unit constituting the resin (for example, the content of (meth) acrylic acid) .

The weight average molecular weight (Mw) of the resin may be 10000 or more, 20000 or more, or 25000 or more, from the viewpoint of excellent adhesion (developer resistance) of the cured product of the photosensitive composition, and may be 100000 or less, 80000 or less, or 60000 or less, from the viewpoint of suitable development. The degree of dispersion (Mw/Mn) of the resin may be, for example, 1.0 or more or 1.5 or more, and may be 3.0 or less or 2.5 or less from the viewpoint of further improving the adhesiveness and the resolution.

The weight average molecular weight and the degree of dispersion may be measured by, for example, gel permeation chromatography (GPC) and use of a calibration curve plotted for standard polystyrene. More specifically, the measurement may be carried out under conditions described in the Examples section. When a compound with a low molecular weight is subjected to measurement and it is difficult to measure the weight average molecular weight by the method described above, the weight average molecular weight of the compound may be determined by measuring the molecular weight of the compound by a different method and then calculating the average value.

The content of the resin based on the total solid content of the photosensitive composition may be 20%by mass or more, 30%by mass or more, or 40%by mass or more, from the viewpoint of excellent film formability, and may be 90%by mass or less, 80%by mass or less, or 65%by mass or less, from the viewpoint of further excellent sensitivity and resolution.

The content of the resin with respect to 100 parts by mass of the total amount of the resin and the photopolymerizable compound may be 30 parts by mass or more, 35 parts by mass or more, or 40 parts by mass or more, from the viewpoint of excellent film formability, and may be 70 parts by mass or less, 65 parts by mass or less, or 60 parts by mass or less, from the viewpoint of further improving sensitivity and resolution.

The photosensitive composition may further contain one, or, two or more additional components other than any of the components described above. Examples of these additional components include a hydrogen donor (such as bis [4- (dimethylamino) phenyl] methane, bis [4- (diethylamino) phenyl] methane, leuco crystal violet, and N-phenylglycine) , a dye (such as malachite green) , tribromophenyl sulfone, a photochromic agent, an agent for preventing thermochromic phenomena, a plasticizer (such as p-toluenesulfonamide) , a pigment, a filler, an antifoaming agent, a flame retardant, a stabilizer, an adhesion promoter, a leveling agent, a peeling promoter, an antioxidant, a perfume, an imaging agent, and a thermal crosslinking agent. The content of the additional components may be 0.005%by mass or more or 0.01%by mass or more, and may be 20%by mass or less, based on the total solid content of the photosensitive composition.

The photosensitive composition may further contain one, or, two or more organic solvents from the viewpoint of viscosity control. Examples of the organic solvents include methanol, ethanol, acetone, methyl ethyl ketone, methyl cellosolve, ethyl cellosolve, toluene, N, N-dimethylformamide, and propylene glycol monomethyl ether. The content of the organic solvents based on the total content of the photosensitive composition may be 40%by mass or more and may be 70%by mass or less.

The photosensitive composition may be suitable for use in resist patterning and may be particularly suitable for use in a method of producing a wiring board described below.

Fig. 1 is a schematic sectional view of a photosensitive element according to an embodiment. As shown in Fig. 1, a photosensitive element 1 includes a support 2, a photosensitive layer 3 disposed on the support 2, and a protective layer 4 disposed on the photosensitive layer 3 on a side opposite to the support 2.

Each of the support 2 and the protective layer 4 may be constituted of a polymer film having heat resistance and solvent resistance; and may be constituted of, for example, a polyester film such as a polyethylene terephthalate film, or a polyolefin film such as a polyethylene film or a polypropylene film. Each of the support 2 and the protective layer 4 may be a film of a hydrocarbon-based polymer other than polyolefin. A film of the hydrocarbon-based polymer including polyolefin may have a low density, and may have, for example, a density of 1.014 g/cm or less. Each of the support 2 and the protective layer 4 may be a stretch film obtained by stretching the hydrocarbon-based polymer film having a low density. The type of the polymer film constituting the protective layer 4 may be the same or different from that of the polymer film constituting the support 2.

These polymer films may be commercially available as, for example, polyethylene terephthalate films such as the PS product line (PS-25, for example) manufactured by Teijin Limited, polyethylene films such as NF-15 manufactured by Tamapoly Co., Ltd., polypropylene films manufactured by Oji Paper Co., Ltd. (Alphan MA-410 and E-200C, for example) , and polypropylene films manufactured by Shin-Etsu Film Co., Ltd.

The thickness of the support 2 may be 1 μm or more or 5 μm or more from the viewpoint of inhibiting potential damage caused to the support 2 while the support 2 is peeled off the photosensitive layer 3; and may be 100 μm or less, 50 μm or less, or 30 μm or less from the viewpoint of proper exposure through the support 2.

The thickness of the protective layer 4 may be 1 μm or more, 5 μm or more, or 15 μm or more from the viewpoint of inhibiting potential damage caused to the protective layer 4 while the protective layer 4 is peeled off and the photosensitive layer 3 and the support 2 are laminated with a substrate; and may be 100 μm or less, 50 μm or less, or 30 μm or less from the viewpoint of improvement in productivity.

The photosensitive layer 3 is constituted of the photosensitive composition described above. The thickness of the photosensitive layer 3 after drying (or after organic solvent volatilization when the photosensitive composition contains an organic solvent) may be 1 μm or more or 5 μm or more from the viewpoint of easy application and improved productivity; and may be 100 μm or less, 50 μm or less, or 40 μm or less from the viewpoint of further improvement in adhesion and resolution.

The photosensitive element 1 may be obtained as follows, for example. First, the photosensitive layer 3 is formed on the support 2. The formation of the photosensitive layer 3 may be carried out by, for example, applying a photosensitive composition containing an organic solvent to form a coating layer and drying the resulting coating layer. Subsequently, the protective layer 4 is formed on the photosensitive layer 3 on a side opposite to the support 2.

The formation of the coating layer may be carried out by, for example, a known method, such as roll coating, comma coating, gravure coating, air knife coating, die coating, or bar coating. The coating layer is dried in such a way that the amount of the organic solvent remaining in the photosensitive layer 3 becomes 2%by mass or less, for example. More specifically, the drying is carried out at 70℃ to 150℃for about 5 minutes to 30 minutes, for example.

In another embodiment, the photosensitive element may include no protective layer and may further include an additional layer such as a cushioning layer, an adhesive layer, a light-absorbing layer, and a gas barrier layer.

The photosensitive element 1 may be, for example, a photosensitive element sheet or a photosensitive element roll that is a roll of the photosensitive element wound around a core. When the photosensitive element 1 is such a photosensitive element roll, it is preferable that the support 2 be on the outside. The core is made of polyethylene, polypropylene, polystyrene, polyvinyl chloride, or an acrylonitrile-butadiene-styrene copolymer, for example. An end face of the photosensitive element roll may have an end-face separator disposed thereon from the viewpoint of protecting the end face and may have a moisture-proof end-face separator disposed thereon from the viewpoint of avoiding edge fusion. The photosensitive element 1 may be wrapped with a black sheet having low moisture permeability, for example.

The photosensitive element 1 may be suitable for use in resist patterning, particularly suitable for use in a method of producing a wiring board described below. The photosensitive element 1 is capable of inhibiting penetration of a photosensitizer into a polyethylene film compared to a conventional photosensitive element, and therefore at least one of the support 2 and the protective layer 4 can be constituted of a polyethylene film, or can be constituted of the hydrocarbon-based polymer film having a low density or the stretch film thereof.

Fig. 2 is a scheme view showing a method of producing a wiring board (also called printed wiring board) according to an embodiment. In this method, as shown in Fig. 2 (a) , a substrate (for example, a substrate on which a circuit is to be formed) is prepared in which the substrate has an insulating layer 11 and a conductor layer 12 formed on the insulating layer 11. The conductor layer 12 may be a metal copper layer, for example.

Subsequently, as shown in Fig. 2 (b) , a photosensitive layer 13 is formed on the substrate (conductor layer 12) . In this step, the photosensitive layer 13 consisting of the photosensitive composition described above is formed on the substrate (conductor layer 12) by using the photosensitive composition described above or the photosensitive element 1. For example, the formation of the photosensitive layer 13 is carried out by applying the photosensitive composition to the substrate and drying the photosensitive composition. Alternatively, the formation of the photosensitive layer 13 is carried out by removing the protective layer 4 from the photosensitive element 1 and then heating the photosensitive layer 3 of the photosensitive element 1 for thermocompression bonding to the substrate. During the thermocompression bonding, at least one of the photosensitive layer 3 and the substrate may be heated at 70℃ to 130℃, for example. The pressure applied in the thermocompression bonding may be 0.1 MPa to 1.0 MPa, for example.

Subsequently, as shown in Fig. 2 (c) , a mask 14 is placed on the photosensitive layer 13 and an active ray 15 is applied thereto. As a result, an area other than the area with the mask 14 placed thereon is subjected to exposure and thereby the photosensitive layer 13 is photocured. The light source of the active ray 15 may be an ultraviolet light source or a visible light source, such as a carbon arc lamp, a mercury vapor arc lamp, a high-pressure mercury lamp, a xenon lamp, a gas laser (an argon laser, for example) , a solid-state laser (aYAG laser, for example) , or a semiconductor laser.

In another embodiment, instead of the mask 14, a direct image exposure method such as LDI exposure method or DLP exposure method may be used. In that case, the active ray 15 may be applied in a desired pattern so that only a part of the photosensitive layer 13 is exposed to light.

Subsequently, as shown in Fig. 2 (d) , an area (uncured part) other than a photocured part formed by exposure is removed from the substrate by development and thereby a resist pattern 16 consisting of the photocured part (the cured product of the photosensitive layer) is formed. The method of development may be wet development or dry development, for example, preferably wet development.

Wet development is carried out by using a developer solution applicable to the photosensitive composition and by such a technique as dipping, using a paddle, spraying, brushing, slapping, scrubbing, or dipping and shaking. The developer solution is selected as appropriate depending on the composition of the photosensitive composition and may be an alkaline developer solution or an organic solvent developer solution.

The alkaline developer solution may be an aqueous solution containing such a base as an alkali hydroxide, such as a hydroxide of lithium, sodium, or potassium; an alkali carbonate, such as a carbonate or a bicarbonate of lithium, sodium, potassium, or ammonium; an alkali metal phosphate, such as potassium phosphate or sodium phosphate; an alkali metal pyrophosphate, such as sodium pyrophosphate or potassium pyrophosphate; borax; sodium metasilicate; tetramethylammonium hydroxide; ethanolamine; ethylenediamine; diethylenetriamine; 2-amino-2-hydroxymethyl-1, 3-propanediol; 1, 3-diamino-2-propanol; or morpholine.

The alkaline developer solution may be, for example, an aqueous solution of sodium carbonate at 0.1%by mass to 5%by mass, an aqueous solution of potassium carbonate at 0.1%by mass to 5%by mass, an aqueous solution of sodium hydroxide at 0.1%by mass to 5%by mass, or an aqueous solution of sodium tetraborate at 0.1%by mass to 5%by mass. The alkaline developer solution may have pH9 to pH11, for example.

The alkaline developer solution may further contain a surfactant, an antifoaming agent, and/or an organic solvent, for example. Examples of the organic solvent include acetone, ethyl acetate, an alkoxyethanol having a C1 to C4 alkoxy group, ethyl alcohol, isopropyl alcohol, butyl alcohol, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, and diethylene glycol monobutyl ether. The content of the organic solvent based on the total amount of the alkaline developer solution may be 2%by mass to 90%by mass.

The organic solvent developer solution may contain an organic solvent such as 1, 1, 1-trichloroethane, N-methylpyrrolidone, N, N-dimethylformamide, cyclohexanone, methyl isobutyl ketone, or γ-butyrolactone. The organic solvent developer solution may further contain 1%by mass to 20%by mass of water.

In this step, following the removal of the unexposed part, the resultant may be heated at 60℃ to 250℃ or subjected to further exposure at 0.2 J/cm ² to 10 J/cm ² as needed for further curing the resist pattern 16.

Subsequently, as shown in Fig. 2 (e) , the part of the conductor layer 12 on which the resist pattern 16 is not formed is subjected to plating treatment, for example, and thereby a wiring layer 17 is formed on that part. The type of material constituting the wiring layer 17 may be the same as or different from that of the conductor layer 12. Trace layer 17 may be a metal copper layer, for example. As the plating treatment, either or both of electrolytic plating treatment and electroless plating treatment may be employed.

Subsequently, as shown in Fig. 2 (f) , the resist pattern 16 is removed and a part of the conductor layer 12 disposed at a position corresponding to the resist pattern 16 is removed. As a result, a wiring board 18 is obtained which is constituted of the substrate and the wiring layer 17 formed on the substrate.

The removal of the resist pattern 16 may be carried out by, for example, development with the use of an aqueous solution of strong alkali by such a technique as dipping or spraying. The aqueous solution of strong alkali may be an aqueous solution of sodium hydroxide at 1%by mass to 10%by mass or an aqueous solution of potassium hydroxide at 1%by mass to 10%by mass, for example.

The removal of the conductor layer 12 may be carried out by etching treatment. The etchant liquid is selected as appropriate depending on the type of the conductor layer 12 and may be a cupric chloride solution, a ferric chloride solution, an alkaline etchant solution, or a hydrogen peroxide etchant liquid, for example.

Examples

Next, the present invention is further more specifically described referring to examples. These examples are by no means limitative of the scope of the present invention.

[Synthesis of compound (1-1) : 9, 10-dipropionyloxyanthracene]

9,10-anthraquinone (3.00 g, 14.42 mmol) , Zn (9.43 g, 144.23 mmol) , K ₂CO ₃ (19.93 g, 144.23 mmol) , and THF (60.0 mL) were put into a 100 mL three flask equipped with a stirrer, a nitrogen-introducing tube, a reflux condenser, a dropping funnel, and a thermometer. Propionic anhydride (17.5 mL, 144.23 mmol) was added thereto and stirred for 5 hours.

After completion of the reaction, Zn and K ₂CO ₃ were removed by filtration, 0.1 M HCl was added, dichloroethane (30 mL) was added, and the mixture was stirred, and the organic layer was collected. After the collected organic layer was washed with water and brine, the organic layer was collected again and anhydrous MgSO ₄ was added.

Subsequently, anhydrous MgSO ₄ was removed by filtration, and after drying under reduced pressure, the remaining solid was washed three times each with hexane (30 mL) and diethyl ether (30 mL) to obtain a compound (1-1) represented by the following formula (1-1) : 9, 10-dipropionyloxyanthracene.

[Synthesis of compound (1-2) : 9, 10-diacetoxyanthracene]

A compound (1-2) represented by the following formula (1-2) : 9, 10-diacetoxyanthracene was synthesized in the same manner as the compound (1-1) except that propionic anhydride was changed to acetic acid anhydride.

[Synthesis of compound (1-3) : 2-bromo-9, 10-dipropionyloxyanthracene]

A compound (1-3) represented by the following formula (1-3) : 2-bromo-9, 10-dipropionyloxyanthracene was synthesized in the same manner as the compound (1-1) except that 9, 10-anthraquinone was changed to 2-bromo-9, 10-anthraquinone.

[Synthesis of compound (1-4) : 2, 3-dimethyl-9, 10-dipropionyloxyanthracene]

A compound (1-4) represented by the following formula (1-4) : 2, 3-dimethyl-9, 10-dipropionyloxyanthracene was synthesized in the same manner as the compound (1-1) except that 9, 10-anthraquinone was changed to 2, 3-dimethyl-9, 10-anthraquinone.

[Synthesis of compound (1-5) : 2-ethyl-9, 10-dipropionyloxyanthracene]

A compound (1-5) represented by the following formula (1-5) : 2-ethyl-9, 10-dipropionyloxyanthracene was synthesized in the same manner as the compound (1-1) except that 9, 10-anthraquinone was changed to 2-ethyl-9, 10-anthraquinone.

[Synthesis of compound (1-6) :

2,9, 10-tripropionyloxyanthracene]

A compound (1-6) represented by the following formula (1-6) :

2,9, 10-tripropionyloxyanthracene was synthesized in the same manner as the compound (1-1) except that 9, 10-anthraquinone was changed to 2-hydroxy-9, 10-anthraquinone.

[Synthesis of compound (1-7) :

2-chloro-9, 10-dipropionyloxyanthracene]

A compound (1-7) represented by the following formula (1-7) :

2-chloro-9, 10-dipropionyloxyanthracene was synthesized in the same manner as the compound (1-1) except that 9, 10-anthraquinone was changed to 2-chloro-9, 10-anthraquinone.

UVS-581 (trade name, manufactured by Kawasaki Kasei Chemicals Ltd. ) was used as a compound (1-8) : 9, 10-dioctanoyloxyanthracene (acompound represented by the following formula (1-8) ) .

UVS-1331 (trade name, manufactured by Kawasaki Kasei Chemicals Ltd. ) was used as a compound (1-9) : 9, 10-dibutoxyanthracene (DBA, a compound represented by the following formula (1-9) ) .

[Synthesis of acrylic resin]

A 1000 mL three flask equipped with a stirrer, a nitrogen inlet tube, a reflux condenser, a dropping funnel, and a thermometer was charged with 96g of propylene glycol monomethyl ether (MFG) and 64g of toluene, and the temperature was increased to 80 ℃ under a nitrogen atmosphere. A mixture of 36g of methacrylic acid, 48g of styrene, 36g of benzyl methacrylate (mass ratio 30/40/30) , and 9g of azobisisobutyronitrile (AIBN) was added dropwise to the flask over 3 hours, a mixture of 6 g of MFG, 4g of toluene, and 0.20g of AIBN was added dropwise over 2 hours, and 6 g of MFG and 4g of toluene were added dropwise to carry out the reaction. The reaction solution was heated to 95℃ and stirred for 1.5 hours, and then cooled to room temperature to obtain a solution of an alkali-soluble acrylic resin. The nonvolatile content (solid content) of the solution was 40%by mass.

[Preparation of photosensitive composition]

(Example 1)

A photosensitive composition was obtained by mixing 25 parts by mass of 2, 2-bis (4- (methacryloxypentaethoxy) phenyl) propane (FA-321M (trade name) , manufactured by Showa Denko Materials Co., Ltd. ) , 10 parts by mass of polyalkylene glycol di (meth) acrylate (FA-023M (trade name) , manufactured by Showa Denko Materials Co., Ltd. ) , 5 parts by mass of 2-hydroxy-3-chloro propyl-2-methacryloyloxyethyl phthalate (FA-MECH (trade name) , manufactured by Showa Denko Materials Co., Ltd. ) , as photopolymerizable compounds, 3.7 parts by mass of 2, 2’-bis (2-chlorophenyl) -4, 4’, 5, 5’-tetraphenyl-1, 2’-biimidazole (manufactured by Hampford, referred to as "photopolymerization initiator (A-1) " ) as a photopolymerization initiator, 0.7 parts by mass of the compound (1-1) as a photosensitizer, 60 parts by mass of the alkali-soluble acrylic resin (binder resin) synthesized by the above procedure, 0.5 parts by mass of leuco crystal violet (manufactured by Yamada Chemical Co., Ltd. ) as a hydrogen donor compound, and 0.03 parts by mass of malachite green (manufactured by Osaka Organic Chemical Industry Ltd. ) as a dye.

(Examples 2 to 7 and Comparative Examples 1 and 2)

Photosensitive compositions were obtained in the same manner as in Example 1 except that any one of the compounds (1-2) to (1-9) shown in Table 1 was used as the photosensitizer instead of the compound (1-1) .

(Comparative Example 3)

A photosensitive composition was obtained in the same manner as in Example 1 except that 2-hydroxy-2-methyl-1-phenylpropan-1-one (referred to as "photopolymerization initiator (A-2) " ) was used as the photopolymerization initiator instead of the photopolymerization initiator (A-1) , and the compound (1-2) was used as the photosensitizer instead of the compound (1-1) .

[Preparation of photosensitive element]

The photosensitive composition was applied onto a polyethyleneterephthalate (PET) film (manufactured by Teijin Film Solutions Co., Ltd., trade name "G2J" ) (support) having a thickness of 16 μm, and dried in hot air convection dryers at 75℃ and 125℃sequentially to form a photosensitive layer having a thickness of 25 μm after drying. A polyethylene film (manufactured by Tamapoly Co., Ltd., product name "NF-15" ) (protection layer) was bonded onto the photosensitive layer to obtain a photosensitive element in which the support, the photosensitive layer, and the protection layer were laminated in this order.

[Evaluation of migration of photosensitizer into polyethylene film]

The photosensitive element produced above was packed with a black sheet and left to stand in an environment of yellow light for 24 hours, and then the polyethylene film was peeled off from the photosensitive element. The peeled polyethylene film was measured for absorbance Abs (Sample) at 405 nm using an ultraviolet-visible spectrophotometer (manufactured by Shimadzu Corporation (UV-1800) ) . Further, the absorbance Abs (Ref) at 405 nm of the same polyethylene film (new) as that used in the production of the photosensitive element was measured in the same manner as described above. From the measured absorbance, the presence or absence of migration was evaluated based on the following criteria:

Absence of migration: Abs (Sample) -Abs (Ref) < 0.01

Presence of migration: Abs (Sample) -Abs (Ref) ≥ 0.01.

[Preparation of stack]

A copper-clad laminate (trade name "MCL-E -67" , manufactured by Showa Denko Materials Co., Ltd. ) in which a copper foil (thickness: 35 μm) was laminated on both surfaces of a glass fiber-reinforced epoxy layer was washed with water, pickled, washed with water, and dried with an air stream. The copper clad laminate was then heated to 80℃ and the photosensitive element was laminated to the copper surface of the copper clad laminate. The lamination was performed using a heat roll at 110℃ under a pressure of 0.4 MPa of substrate at a roll speed of 1.0 m/min while removing the protection layer. Thus, stack in which the copper-clad laminate, the photosensitive layer, and support were laminated in this order was obtained.

[Evaluation of sensitivity]

(Evaluation using low-illuminance light source)

A 41 stage step tablet (manufactured by Showa Denko Materials Co., Ltd. ) was placed on the obtained support of stack, and exposure was performed at 100 mJ/cm ² using a direct drawing exposure machine (manufactured by Via Mechanics Co., Ltd. (DE-1UH) , exposure wavelength: 405 nm) .

Next, the photosensitive layer was developed with a 1%by mass sodium carbonate aqueous solution at 30℃, and the developing time at which the residual film became zero was measured. Development processing was performed for 2 times the obtained development time, and the number of steps of the step tablet remaining on the substrate (the number of ST steps) was evaluated. A larger number of ST stages means higher sensitivity. The results are shown in Table 1. Table 1 shows relative values when the number of ST stages of Comparative Example 2 is 1.0.

(Evaluation using high-illuminance light source)

The sensitivity was evaluated in the same manner as in the evaluation using the low-illuminance light source, except that the exposure was performed at 40 100 mJ/cm ² using a direct drawing exposure machine (manufactured by Orbotech (Fine 8) , exposure wavelength: 405 nm) as an exposure machine.

[Evaluation of adhesiveness]

A pattern was drawn on the support of the stack with an exposure amount corresponding to the number of ST stages = 16 stages using a direct drawing exposure machine (manufactured by Via Mechanics Co., Ltd. (DE-1UH) , exposure wavelength: 405 nm) . After the development treatment, the size n (μm) of the line portion in the isolated pattern in which the line portion (μm) /space portion (μm) = n (μm) /400 (μm) is the smallest was measured in the resist pattern in which the space portion (unexposed portion) was completely removed and the line portion (exposed portion) was formed without meandering or chipping. A smaller size means higher adhesion. The results are shown in Table 1.

[Absorbance of photosensitive element]

The polyethylene film was peeled from the produced photosensitive element, and the absorbance at 405 nm was measured using an ultraviolet-visible spectrophotometer (manufactured by Shimadzu Corporation (UV-1800) ) . The results are shown in Table 1.

As can be seen from Table 1, in a case where the hexaarylbiimidazole compound is used as the photopolymerization initiator, when DBA or the like is used as the photosensitizer, the migration to the polyethylene film occurs (Comparative Examples 1 and 2) , whereas when the compound represented by the formula (1) is used as the photosensitizer, the migration to the polyethylene film is suppressed (Examples 1 to 7) . On the other hand, when a compound other than the hexaarylbiimidazole compound is used as the photopolymerization initiator and the compound represented by the formula (1) is used as the photosensitizer (Comparative Example 3) , the migration to the polyethylene film is suppressed, however, the sensitivity (in particular, sensitivity when a low-illuminance light source is used) is lower than when the hexaarylbiimidazole compound is used as the photopolymerization initiator and the compound represented by the formula (1) is used as the photosensitizer (Examples 1 to 7) . In addition, the photosensitive compositions containing the combination of the hexaarylbiimidazole compound and the compound represented by the formula (1) (Examples 1 to 7) are also excellent in terms of adhesiveness to the substrate.

Reference Signs List

1: photosensitive element, 2: support, 3, 13: photosensitive layer, 4: protective layer, 16: resist pattern, 17: wiring layer, 18: wiring board.

Claims

A photosensitive composition comprising:

a photopolymerizable compound;

a hexaarylbiimidazole compound; and

a compound represented by the following formula (1) :

wherein R ¹, R ² and R ³ each independently represent an alkyl group having 5 or less carbon atoms, R ⁴ represents a halogen atom, an alkyl group or an alkoxy group, and m and n each independently represent an integer of 0 or more.
The photosensitive composition according to claim 1, wherein the alkyl group represented by R ¹, R ² and R ³ in the formula (1) has 2 or more carbon atoms.
The photosensitive composition according to claim 1 or 2, wherein m and n are 0 in the formula (1) .
The photosensitive composition according to claim 1 or 2, wherein m is 1 and n is 0 in the formula (1) .
The photosensitive composition according to claim 1 or 2, wherein m is 0 and n is 1 in the formula (1) .
The photosensitive composition according to claim 1 or 2, wherein m is 0 and n is 2 in the formula (1) .
The photosensitive composition according to claim 1 or 2, wherein the compound represented by the formula (1) is a compound represented by the following formula (6) :

wherein R ¹ and R ² have the same meanings as R ¹ and R ² in Formula (1) , respectively, and R ⁴ represents a halogen atom.
The photosensitive composition according to claim 7, wherein the halogen atom is chlorine atom.
A photosensitive element comprising:

a support; and

a photosensitive layer disposed on the support, the photosensitive layer comprising the photosensitive composition according to claim 1 or 2.
A method of producing a wiring board, comprising:

disposing a photosensitive layer comprising the photosensitive composition according to claim 1 or 2 on a substrate;

photocuring a part of the photosensitive layer;

removing an uncured part of the photosensitive layer to form a resist pattern; and

forming a wiring layer on a part of the substrate on which no resist pattern is formed.