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

Abstract

To provide a photosensitive composition that can suppress migration of photosensitizer to a polyethylene film.SOLUTION: A photosensitive composition contains a photopolymerizable compound, a hexaarylbiimidazole compound and a compound represented by the following formula (1). In the formula, R1, R2 and R3 independently represent an alkyl group having 5 or less carbon atoms, R4 represents a halogen atom, an alkyl group or an alkoxy group, and m and n independently represent an integral number of 0 or more.SELECTED DRAWING: Figure 1

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to International Application No. PCT / CN2021 / 106686, filed July 16, 2021, the entire contents of which are incorporated herein by reference. [Technical Field]

[0002] The present disclosure relates to a photosensitive composition, a photosensitive element, and a method for manufacturing a wiring substrate. [Background technology]

[0003] In the manufacture of wiring boards, a resist pattern is formed to obtain desired wiring. Photosensitive compositions are widely used to form resist patterns. In recent years, MSAP (Modified Semi-Additive Process) has attracted attention as a method capable of forming fine wiring. In this method, to form fine wiring, it is necessary to form the resist pattern with higher accuracy than conventional methods.

[0004] In order to form a resist pattern with high precision, a photosensitive composition generally contains a photosensitizer 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, and 9,10-dibutoxyanthracene (DBA) is used as the photosensitizer (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] International Publication No. 2007 / 123062 Summary of the Invention [Problem to be solved by the invention]

[0006] According to the studies of the present inventors, when a hexaarylbiimidazole compound is used as a photopolymerization initiator, as in Patent Document 1, further consideration is needed in the selection of a photosensitizer. Specifically, photosensitive compositions are usually used in the form of a photosensitive element sandwiched between polymer films. However, according to the studies of the present inventors, when a photosensitive composition contains DBA in addition to a hexaarylbiimidazole compound, the DBA may migrate into the polymer film, resulting in a problem (migration) in which the desired pattern shape cannot be formed during resist pattern formation. This problem occurs particularly noticeably when the polymer film is a polyethylene film.

[0007] Therefore, an object of one aspect of the present invention is to provide a photosensitive composition that can suppress migration of a photosensitizer into a polyethylene film. [Means for solving the problem]

[0008] The present inventors have found that by selecting a specific compound as a photosensitizer to be used together with a hexaarylbiimidazole compound, migration of the photosensitizer into a polyethylene film can be suppressed compared to when DBA is used as the photosensitizer.

[0009] The present invention includes the following aspects. [1] A photosensitive composition containing a photopolymerizable compound, a hexaarylbiimidazole compound, and a compound represented by the following formula (1): [ka] In the formula, R 1 , R 2 and R 3 each independently represents an alkyl group having 5 or less carbon atoms, and 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.

[0010] [2] R in Equation (1) 1, R 2 and R 3 The photosensitive composition according to [1], wherein the alkyl group represented by the formula (I) has 2 or more carbon atoms. [3] The photosensitive composition according to [1] or [2], wherein m and n in formula (1) are 0. [4] The photosensitive composition according to [1] or [2], wherein m is 1 and n is 0 in formula (1). [5] The photosensitive composition according to [1] or [2], wherein m is 0 and n is 1 in formula (1). [6] The photosensitive composition according to [1] or [2], wherein m is 0 and n is 2 in formula (1).

[0011] [7] The photosensitive composition according to [1] or [2], wherein the compound represented by formula (1) is a compound represented by the following formula (6): [ka] In the formula, R 1 and R 2 is R in Equation (1). 1 and R 2 are synonymous with R 4 represents a halogen atom. [8] The photosensitive composition according to [7], wherein the halogen atom is a chlorine atom.

[0012] [9] A photosensitive element comprising: a support; and a photosensitive layer provided on the support and made of the photosensitive composition according to any one of [1] to [8].

[10] A method for manufacturing a wiring board, comprising the steps of: providing a photosensitive layer made of the photosensitive composition according to any one of [1] to [8] on a substrate; photocuring a portion of the photosensitive layer; removing the uncured portion of the photosensitive layer to form a resist pattern; and forming a wiring layer on a portion of the substrate where the resist pattern is not formed. [Effects of the Invention]

[0013] According to one aspect of the present invention, a photosensitive composition capable of suppressing migration of a photosensitizer into a polyethylene film can be provided. According to another aspect of the present invention, a photosensitive composition having excellent sensitivity (particularly sensitivity when a low-illuminance light source is used) can be provided. According to another aspect of the present invention, a photosensitive composition having excellent adhesion to a substrate can be provided. [Brief explanation of the drawings]

[0014] [Figure 1] FIG. 1 is a schematic cross-sectional view illustrating a photosensitive element according to one embodiment. [Figure 2] 1A to 1C are schematic diagrams illustrating a method for manufacturing a wiring substrate according to an embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0015] Hereinafter, embodiments of the present invention will be described in detail. In this specification, the term "process" refers not only to an independent process, but also to a process that cannot be clearly distinguished from other processes, as long as the intended effect of that process is achieved. A numerical range indicated using "to" indicates a range that includes the numerical values ​​before and after "to" as the minimum and maximum values, respectively. The term "layer" encompasses not only a structure that is formed over the entire surface when observed in a plan view, but also a structure that is formed on a portion of the surface. "(Meth)acrylic acid" means at least one of "acrylic acid" and the corresponding "methacrylic acid." The same applies to other similar expressions, such as a (meth)acryloyl group.

[0016] In this specification, the amount of each component in the composition means the total amount of the components present in the composition unless otherwise specified, when the composition contains multiple substances corresponding to each component. In this specification, the term "solid content" refers to the non-volatile content of the photosensitive composition excluding volatile substances (water, solvent, etc.). In other words, the term "solid content" refers to components other than the solvent that remain unvolatilized during drying of the photosensitive composition, as described below, and includes those that are liquid, syrup-like, or waxy at room temperature (25°C).

[0017] <Photosensitive composition> 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). [ka] In the formula, R 1 , R 2 and R 3 each independently represents an alkyl group having 5 or less carbon atoms, and 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.

[0018] The photosensitive composition contains one or more photopolymerizable compounds. The photopolymerizable compound may be any compound that can be polymerized by light, such as a compound having an ethylenically unsaturated bond or a compound having a (meth)acryloyl group.

[0019] The photopolymerizable compound may contain a bisphenol A (meth)acrylate compound from the viewpoint of further improving alkali developability, resolution, and release properties after curing. Examples of the bisphenol A (meth)acrylate compound include 2,2-bis(4-((meth)acryloxypolyethoxy)phenyl)propane (2,2-bis(4-((meth)acryloxypentaethoxy)phenyl)propane, etc.), 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. From the viewpoint of further improving resolution and peeling properties, the photopolymerizable compound may contain 2,2-bis(4-((meth)acryloxypolyethoxy)phenyl)propane (e.g., 2,2-bis(4-((meth)acryloxypentaethoxy)phenyl)propane).

[0020] From the viewpoint of further improving the resolution of the resist, the content of the bisphenol A type (meth)acrylate 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, based on the total amount of the photopolymerizable compound.

[0021] To further improve resolution and flexibility, the photopolymerizable compound may contain an α,β-unsaturated ester compound obtained by reacting a polyhydric alcohol with an α,β-unsaturated carboxylic acid. 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.

[0022] The content of the α,β-unsaturated ester compound may be 20% by mass or more or 30% by mass or more, based on the total amount of the photopolymerizable compound, from the viewpoint of improving flexibility, and may be 70% by mass or less or 60% by mass or less, from the viewpoint of further improving resolution.

[0023] The photopolymerizable compound may include a phthalate ester compound, a (meth)acrylic acid alkyl ester, nonylphenoxy polyethyleneoxyacrylate, a photopolymerizable compound having at least one cationically polymerizable cyclic ether group in the molecule (such as an oxetane compound), etc. The photopolymerizable compound may include a phthalate compound from the viewpoint of further suitably improving the resolution, adhesion, resist shape, and release properties after curing.

[0024] The phthalate ester compound may be, for example, a compound having a phthalate ester structure and a (meth)acryloyl group. Such a compound may be γ-chloro-β-hydroxypropyl-β'-(meth)acryloyloxyethyl-o-phthalate (also known as 3-chloro-2-hydroxypropyl-2-(meth)acryloyloxyethyl phthalate), β-hydroxyethyl-β'-(meth)acryloyloxyethyl-o-phthalate, β-hydroxypropyl-β'-(meth)acryloyloxyethyl-o-phthalate, or the like, and is preferably γ-chloro-β-hydroxypropyl-β'-(meth)acryloyloxyethyl-o-phthalate.

[0025] When the photopolymerizable compound contains a phthalate ester-based compound, the content of the phthalate ester-based compound may be 1% by mass or more, 3% by mass or more, or 5% by mass or more, and may be 30% by mass or less, 25% by mass or less, or 20% by mass or less, based on the total amount of the photopolymerizable compound, from the viewpoint of further suitably improving the resolution, adhesion, resist shape, and release properties after curing.

[0026] The content of the photopolymerizable compound may be 3% by mass or more, 10% by mass or more, or 25% by mass or more, based on the total solid content of the photosensitive composition, from the viewpoint of further improving 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 formability.

[0027] The hexaarylbiimidazole compound is a compound that can function as a photopolymerization initiator and has a structure represented by the following formula (A). [ka] In the formula, Aryl represents an aryl group, and the six aryl groups may be the same or different from each other.

[0028] The aryl group may be, for example, a substituted or unsubstituted phenyl group. The substituted phenyl group may be, for example, a phenyl group in which one or more hydrogen atoms have been substituted with a halogen atom, an alkyl group, or an alkoxy group. The halogen atom may be, for example, a chlorine atom. The number of carbon atoms in the alkyl group may be, for example, one or more and four or less. The alkyl group may be, for example, a methyl group. The number of carbon atoms in the alkoxy group may be, for example, one or more and four or less. The alkoxy group may be, for example, a methoxy group.

[0029] 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, etc., and is preferably 2,2'-bis(2-chlorophenyl)-4,4',5,5'-tetraphenyl-1,2'-biimidazole.

[0030] From the viewpoint of further improving sensitivity and adhesion, the content of the hexaarylbiimidazole compound may be 0.1 mass % or more, 0.5 mass % or more, or 1 mass % or more, and may be 20 mass % or less, 10 mass % or less, or 5 mass % or less, based on the total solid content of the photosensitive composition.

[0031] The compound represented by the above formula (1) is a compound that can function as a photosensitizer. 1 , R 2 and R 3 The alkyl group represented by the formula (I) may be linear or branched. The number of carbon atoms in the alkyl group may be 1 or more, 2 or more, 4 or less, 3 or less, or even 2. When m is an integer of 2 or more, a plurality of R 3 may be the same or different from each other.

[0032] In formula (1), R 4 The halogen atom represented by R may be, for example, a chlorine atom or a bromine atom.4 The alkyl group represented by the formula (I) may be linear or branched. The number of carbon atoms in the alkyl group may be 1 or more, 5 or less, 4 or less, 3 or less, or 2 or less, or may be 1 or 2. 4 The alkoxy group represented by the formula (I) may be linear or branched. The number of carbon atoms in the alkoxy group may be 1 or more and 5 or less. When n is an integer of 2 or more, a plurality of R 4 may be the same or different. 4 is preferably a halogen atom, more preferably a chlorine atom, from the viewpoint of increasing the sensitivity of the photosensitive composition to both low-intensity and high-intensity light sources.

[0033] In formula (1), m may be an integer of 1 or greater, and may be an integer of 3 or less, 2 or less, or 1 or less. n may be an integer of 1 or greater, and may be an integer of 3 or less, or 2 or less.

[0034] In one embodiment, m and n may be 0. That is, in one embodiment, the compound represented by formula (1) may be a compound represented by the following formula (2). [ka] In the formula, R 1 and R 2 is R in Eq. (1) 1 and R 2 are synonymous with each other.

[0035] In one embodiment, m may be 1 and n may be 0. That is, in one embodiment, the compound represented by formula (1) may be a compound represented by the following formula (3) or a compound represented by the following formula (4). [ka] [ka] In the formula, R 1 , R 2 and R 3 is R in Eq. (1) 1 , R 2 and R 3 are synonymous with each other.

[0036] In one embodiment, m may be 0 and n may be 1. That is, in one embodiment, the compound represented by formula (1) may be a compound represented by the following formula (5) or a compound represented by the following formula (6). [ka] [ka] In the formula, R 1 , R 2 and R 4 is R in Eq. (1) 1 , R 2 and R 4 are synonymous with each other.

[0037] In one embodiment, m may be 0 and n may be 2. That is, in one embodiment, the compound represented by formula (1) may be a compound represented by the following formula (7) or a compound represented by the following formula (8). [ka] [ka] In the formula, R 1 , R 2 and R 4 is R in Eq. (1) 1 , R 2 and R 4 are synonymous with each other.

[0038] From the viewpoint of further improving sensitivity, 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 the accuracy of pattern formation, the content of the compound represented by formula (1) is, for example, 10% by mass or less, preferably 5% by mass or less, more preferably 3% by mass or less, even 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.

[0039] The photosensitive composition may further contain a resin (binder resin). The resin may be an alkali-soluble resin from the viewpoint of enabling suitable development with an alkali.

[0040] Examples of the resin include acrylic resins. The acrylic resins 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 ester include a (meth)acrylic acid alkyl ester, a (meth)acrylic acid cycloalkyl ester, and a (meth)acrylic acid aryl ester.

[0041] From the viewpoint of further improving resolution and adhesion, the acrylic resin may further contain styrene or a styrene derivative as a monomer unit. The styrene derivative may be, for example, vinyltoluene, α-methylstyrene, etc. The acrylic resin preferably contains, as monomer units, (meth)acrylic acid, a (meth)acrylic acid ester, and styrene or a styrene derivative.

[0042] 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 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 (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 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 styrene and styrene derivatives may be, for example, 5% by mass or more, 10% by mass or more, or 20% by mass or more, and 65% by mass or less, 55% by mass or less, or 50% by mass or less, based on the total amount of monomer units constituting the acrylic resin.

[0043] 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 enabling suitable development, 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 adhesion (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 units constituting the resin (for example, the content of (meth)acrylic acid).

[0044] The weight average molecular weight (Mw) of the resin may be 10,000 or more, 20,000 or more, or 25,000 or more from the viewpoint of excellent adhesion (developer resistance) of a cured product of the photosensitive composition, and may be 100,000 or less, 80,000 or less, or 60,000 or less from the viewpoint of suitable development. The polydispersity (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 adhesion and resolution.

[0045] The weight-average molecular weight and dispersity can be measured, for example, by gel permeation chromatography (GPC) using a calibration curve of standard polystyrene. More specifically, they can be measured under the conditions described in the Examples. For compounds with low molecular weights, if it is difficult to measure the weight-average molecular weight using the above-mentioned method, the molecular weight can be measured by another method and the average can be calculated.

[0046] The resin content may be 20% by mass or more, 30% by mass or more, or 40% by mass or more, based on the total solid content of the photosensitive composition, 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 even better sensitivity and resolution.

[0047] The resin content may be 30 parts by mass or more, 35 parts by mass or more, or 40 parts by mass or more, relative to 100 parts by mass of the total amount of the resin and the photopolymerizable compound, 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.

[0048] The photosensitive composition may further contain one or more other components in addition to the components described above. Examples of other components include hydrogen donors (such as bis[4-(dimethylamino)phenyl]methane, bis[4-(diethylamino)phenyl]methane, leucocrystal violet, and N-phenylglycine), dyes (such as malachite green), tribromophenyl sulfone, photocoloring agents, thermal color-developing inhibitors, plasticizers (such as p-toluenesulfonamide), pigments, fillers, antifoaming agents, flame retardants, stabilizers, adhesion promoters, leveling agents, release promoters, antioxidants, fragrances, imaging agents, and thermal crosslinkers. The content of these other 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 solids content of the photosensitive composition.

[0049] The photosensitive composition may further contain one or more organic solvents to adjust the viscosity. Examples of 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 solvent may be 40% by mass or more and 70% by mass or less, based on the total amount of the photosensitive composition.

[0050] The photosensitive composition can be suitably used for forming a resist pattern, and can be particularly suitably used in the method for producing a wiring board described below.

[0051] <Photosensitive element> Fig. 1 is a schematic cross-sectional view of a photosensitive element according to one embodiment. As shown in Fig. 1, the photosensitive element 1 includes a support 2, a photosensitive layer 3 provided on the support 2, and a protective layer 4 provided on the side of the photosensitive layer 3 opposite the support 2.

[0052] The support 2 and the protective layer 4 may each be a polymer film having heat resistance and solvent resistance, such as a polyester film such as a polyethylene terephthalate film, or a polyolefin film such as a polyethylene film or a polypropylene film. The support 2 and the protective layer 4 may each be a film of a hydrocarbon-based polymer other than polyolefin. A film of a hydrocarbon-based polymer including polyolefin may have a low density, for example, a density of 1.014 g / cm or less. The support 2 and the protective layer 4 may each be a stretched film obtained by stretching such a low-density hydrocarbon-based polymer film. The type of polymer film constituting the protective layer 4 may be the same as or different from the type of polymer film constituting the support 2.

[0053] These polymer films are commercially available, for example, as polyethylene terephthalate films such as the PS series (e.g., PS-25) manufactured by Teijin Limited, polyethylene films such as NF-15 manufactured by Tamapoly Co., Ltd., or polypropylene films manufactured by Oji Paper Co., Ltd. (e.g., Alphan MA-410, E-200C) and Shin-Etsu Film Co., Ltd.

[0054] The thickness of the support 2 may be 1 μm or more or 5 μm or more from the viewpoint of preventing damage to the support 2 when peeling the support 2 from the photosensitive layer 3, and may be 100 μm or less, 50 μm or less, or 30 μm or less from the viewpoint of enabling suitable exposure even when exposure is performed through the support 2.

[0055] 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 suppressing damage to the protective layer 4 when the photosensitive layer 3 and the support 2 are laminated onto the substrate while peeling off the protective layer 4, and may be 100 μm or less, 50 μm or less, or 30 μm or less from the viewpoint of improving productivity.

[0056] The photosensitive layer 3 is made of the above-described photosensitive composition. The thickness of the photosensitive layer 3 after drying (after volatilization of the organic solvent if the photosensitive composition contains an organic solvent) may be 1 μm or more or 5 μm or more from the viewpoints of facilitating coating and improving productivity, and may be 100 μm or less, 50 μm or less, or 40 μm or less from the viewpoints of further improving adhesion and resolution.

[0057] The photosensitive element 1 can be obtained, for example, as follows. First, a photosensitive layer 3 is formed on a support 2. The photosensitive layer 3 can be formed, for example, by applying a photosensitive composition containing an organic solvent to form a coating layer and drying this coating layer. Next, a protective layer 4 is formed on the surface of the photosensitive layer 3 opposite the support 2.

[0058] The coating layer is formed by a known method such as roll coating, comma coating, gravure coating, air knife coating, die coating, bar coating, etc. The coating layer is dried so that the amount of organic solvent remaining in the photosensitive layer 3 is, for example, 2% by mass or less, and specifically, for example, at 70 to 150°C for about 5 to 30 minutes.

[0059] In another embodiment, the photosensitive element may not include a protective layer, and may further include other layers such as a cushion layer, an adhesive layer, a light-absorbing layer, and a gas barrier layer.

[0060] The photosensitive element 1 may be, for example, in the form of a sheet, or may be in the form of a photosensitive element roll wound around a core. In the photosensitive element roll, the photosensitive element 1 is preferably wound with the support 2 facing outward. The core is formed of, for example, polyethylene, polypropylene, polystyrene, polyvinyl chloride, acrylonitrile-butadiene-styrene copolymer, or the like. An end separator may be provided on the end face of the photosensitive element roll from the viewpoint of end face protection, and a moisture-proof end face separator may be provided from the viewpoint of edge fusion resistance. The photosensitive element 1 may be wrapped, for example, in a black sheet with low moisture permeability.

[0061] The photosensitive element 1 can be suitably used for forming a resist pattern, and is particularly suitable for use in the method for producing a wiring board described below. Compared to conventional photosensitive elements, the photosensitive element 1 can suppress migration of the photosensitizer into the polyethylene film, so at least one of the support 2 and the protective layer 4 may be a polyethylene film, or the above-mentioned low-density hydrocarbon-based polymer film or a stretched film thereof.

[0062] <Method of manufacturing wiring board> 2A and 2B are schematic diagrams illustrating a method for manufacturing a wiring board (also called a printed wiring board) according to one embodiment. In this manufacturing method, first, as shown in FIG. 2A, a substrate (e.g., a circuit-forming substrate) is prepared, which includes an insulating layer 11 and a conductor layer 12 formed on the insulating layer 11. The conductor layer 12 may be, for example, a metallic copper layer.

[0063] Next, as shown in FIG. 2(b), a photosensitive layer 13 is provided on the substrate (conductor layer 12). In this step, the photosensitive layer 13 made of the photosensitive composition described above is formed on the substrate (conductor layer 12) using the photosensitive composition or photosensitive element 1 described above. For example, the photosensitive layer 13 is formed by applying the photosensitive composition to the substrate and drying it. Alternatively, the photosensitive layer 13 is formed by removing the protective layer 4 from the photosensitive element 1, and then pressing the photosensitive layer 3 of the photosensitive element 1 to the substrate while heating. During the pressing, at least one of the photosensitive layer 3 and the substrate may be heated, for example, to 70 to 130°C. The pressure during the pressing may be, for example, 0.1 to 1.0 MPa.

[0064] 2(c), a mask 14 is placed on the photosensitive layer 13, and actinic rays 15 are irradiated to expose areas other than the area where the mask 14 is placed, thereby photo-curing the photosensitive layer 13. The light source for the actinic rays 15 may be an ultraviolet or 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 (such as an argon laser), a solid-state laser (such as a YAG laser), or a semiconductor laser.

[0065] In another embodiment, the mask 14 is not used, and a part of the photosensitive layer 13 may be exposed by irradiating the active light 15 in a desired pattern by a direct imaging exposure method such as LDI exposure or DLP exposure.

[0066] 2(d), the areas (uncured areas) other than the photocured areas formed by exposure are removed from the substrate by development to form a resist pattern 16 consisting of the photocured areas (cured product of the photosensitive layer). The development method may be, for example, wet development or dry development, with wet development being preferred.

[0067] Wet development is carried out using a developer suitable for the photosensitive composition by, for example, a dipping method, a puddle method, a spray method, brushing, slapping, scrubbing, swinging immersion, etc. The developer is appropriately selected depending on the constitution of the photosensitive composition, and may be an alkaline developer or an organic solvent developer.

[0068] The alkaline developer may be an aqueous solution containing a base such as an alkali hydroxide such as lithium, sodium, or potassium hydroxide; an alkali carbonate such as lithium, sodium, potassium, or ammonium carbonate or bicarbonate; 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; morpholine, etc.

[0069] The alkaline developer may be, for example, a 0.1 to 5 mass % aqueous sodium carbonate solution, a 0.1 to 5 mass % aqueous potassium carbonate solution, a 0.1 to 5 mass % aqueous sodium hydroxide solution, a 0.1 to 5 mass % aqueous sodium tetraborate solution, etc. The pH of the alkaline developer may be, for example, 9 to 11.

[0070] The alkaline developer may further contain a surfactant, an antifoaming agent, an organic solvent, etc. Examples of the organic solvent include acetone, ethyl acetate, an 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, and diethylene glycol monobutyl ether. The content of the organic solvent may be 2 to 90 mass % based on the total amount of the alkaline developer.

[0071] The organic solvent developer may contain an organic solvent such as 1,1,1-trichloroethane, N-methylpyrrolidone, N,N-dimethylformamide, cyclohexanone, methyl isobutyl ketone, γ-butyrolactone, etc. The organic solvent developer may further contain 1 to 20% by mass of water.

[0072] In this step, after removing the unexposed portion, if necessary, heating at 60 to 250°C or applying 0.2 to 10 J / cm 2 The resist pattern 16 may be further hardened by further exposure to light at 1000 K.

[0073] 2(e), a wiring layer 17 is formed on the portion of the conductor layer 12 where the resist pattern 16 is not formed, for example, by plating. The wiring layer 17 may be formed of the same material as the conductor layer 12, or may be formed of a different material. The wiring layer 17 may be, for example, a metallic copper layer. The plating may be one or both of an electrolytic plating process and an electroless plating process.

[0074] 2(f), the resist pattern 16 is removed, and the conductor layer 12 provided in a position corresponding to the resist pattern 16 is also removed, thereby obtaining a wiring substrate 18 in which the wiring layer 17 is formed on the substrate.

[0075] The resist pattern 16 can be removed by, for example, developing using a strong alkaline aqueous solution by immersion, spraying, etc. The strong alkaline aqueous solution may be, for example, a 1 to 10 mass % sodium hydroxide aqueous solution, a 1 to 10 mass % potassium hydroxide aqueous solution, or the like.

[0076] The conductive layer 12 can be removed by etching. The etching solution is appropriately selected depending on the type of conductive layer 12, and may be, for example, a cupric chloride solution, a ferric chloride solution, an alkaline etching solution, a hydrogen peroxide etching solution, or the like. [Example]

[0077] The present invention will be explained in more detail below with reference to examples, but the present invention is not limited to these examples.

[0078] [Synthesis of Compound (1-1): 9,10-dipropionyloxyanthracene] 9,10-Anthraquinone (3.00 g, 14.42 mmol), Zn (9.43 g, 144.23 mmol), KCO (19.93 g, 144.23 mmol), and THF (60.0 mL) were placed in a 100 mL three-neck flask equipped with a stirrer, a nitrogen inlet tube, a reflux condenser, a dropping funnel, and a thermometer, and the mixture was stirred at room temperature under a nitrogen atmosphere. After that, propionic anhydride (17.5 mL, 144.23 mmol) was added and the mixture was stirred for 5 hours. After the reaction was completed, the mixture was filtered to remove Zn and K2CO3, and 0.1 M HCl was added. After that, dichloroethane (30 mL) was added and stirred, and the organic layer was recovered. The recovered organic layer was washed with water and brine, and then the organic layer was recovered again and anhydrous MgSO4 was added. Subsequently, the anhydrous MgSO4 was removed by filtration, and the mixture was dried under reduced pressure. The remaining solid was then washed three times each with hexane (30 mL) and diethyl ether (30 mL) to obtain a compound (1-1): 9,10-dipropionyloxyanthracene represented by the following formula (1-1). [ka]

[0079] [Synthesis of Compound (1-2): 9,10-Diacetoxyanthracene] Compound (1-2): 9,10-diacetoxyanthracene represented by the following formula (1-2) was synthesized in the same manner as compound (1-1), except that propionic anhydride was changed to acetic anhydride. [ka]

[0080] [Synthesis of Compound (1-3): 2-Bromo-9,10-dipropionyloxyanthracene] Compound (1-3): 2-bromo-9,10-dipropionyloxyanthracene represented by the following formula (1-3) was synthesized in the same manner as compound (1-1), except that 9,10-anthraquinone was changed to 2-bromo-9,10-anthraquinone. [ka]

[0081] [Synthesis of Compound (1-4): 2,3-dimethyl-9,10-dipropionyloxyanthracene] Compound (1-4): 2,3-dimethyl-9,10-dipropionyloxyanthracene represented by the following formula (1-4) was synthesized in the same manner as compound (1-1), except that 9,10-anthraquinone was changed to 2,3-dimethyl-9,10-anthraquinone. [ka]

[0082] [Synthesis of Compound (1-5): 2-ethyl-9,10-dipropionyloxyanthracene] Compound (1-5): 2-ethyl-9,10-dipropionyloxyanthracene represented by the following formula (1-5) was synthesized in the same manner as compound (1-1), except that 9,10-anthraquinone was changed to 2-ethyl-9,10-anthraquinone. [ka]

[0083] [Synthesis of Compound (1-6): 2,9,10-Tripropionyloxyanthracene] Compound (1-6): 2,9,10-tripropionyloxyanthracene represented by the following formula (1-6) was synthesized in the same manner as compound (1-1), except that 9,10-anthraquinone was changed to 2-hydroxy-9,10-anthraquinone. [ka]

[0084] [Synthesis of Compound (1-7): 2-chloro-9,10-dipropionyloxyanthracene] Compound (1-7): 2-chloro-9,10-dipropionyloxyanthracene represented by the following formula (1-7) was synthesized in the same manner as compound (1-1), except that 9,10-anthraquinone was changed to 2-chloro-9,10-anthraquinone. [ka]

[0085] Compound (1-8): UVS-581 (trade name, manufactured by Kawasaki Chemical Industries, Ltd.) was used as 9,10-dioctanoyloxyanthracene (a compound represented by the following formula (1-8)). [ka]

[0086] Compound (1-9): UVS-1331 (trade name, manufactured by Kawasaki Chemical Industries, Ltd.) was used as 9,10-dibutoxyanthracene (DBA, a compound represented by the following formula (1-9)). [ka]

[0087] [Synthesis of acrylic resin] A 1000 mL three-neck flask equipped with a stirrer, nitrogen inlet tube, reflux condenser, dropping funnel, and thermometer was charged with 96 g of propylene glycol monomethyl ether (MFG) and 64 g of toluene and heated to 80 °C under a nitrogen atmosphere. A mixture of 36 g of methacrylic acid, 48 g of styrene, 36 g of benzyl methacrylate (30 / 40 / 30 by mass), and 9 g of azobisisobutyronitrile (AIBN) was added dropwise to the flask over 3 hours, followed by the dropwise addition of a mixture of 6 g of MFG, 4 g of toluene, and 0.20 g of AIBN over 2 hours. Further addition of 6 g of MFG and 4 g of toluene was then performed. The reaction mixture was heated to 95 °C and stirred for 1.5 hours, then cooled to room temperature to yield a solution of an alkali-soluble acrylic resin. The nonvolatile content (solids content) of the solution was 40% by mass.

[0088] [Preparation of Photosensitive Composition] Example 1 The photopolymerizable compound was 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.), and 5 parts by mass of 2-hydroxy-3-chloropropyl-2-methacryloyloxyethyl phthalate (FA-MECH (trade name), manufactured by Showa Denko Materials Co., Ltd.), and the photopolymerization initiator was 2,2'-bis(2-chlorophenyl)propane. A photosensitive composition was obtained by mixing 3.7 parts by mass of (4,4',5,5'-tetraphenyl-1,2'-biimidazole (manufactured by Hampford, referred to as "photopolymerization initiator (A-1)"), 0.7 parts by mass of the above 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 (Osaka Organic Chemical Industry Ltd.) as a dye.

[0089] (Examples 2 to 7 and Comparative Examples 1 and 2) A photosensitive composition was obtained in the same manner as in Example 1, except that, instead of the compound (1-1), one of the compounds (1-2) to (1-9) shown in Table 1 was used as the photosensitizer.

[0090] (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 that the compound (1-2) was used as the photosensitizer instead of the compound (1-1).

[0091] [Preparation of photosensitive element] The photosensitive composition was applied to a 16 μm-thick polyethylene terephthalate (PET) film (Teijin Film Solutions Limited, product name "G2J") (support) and dried sequentially in a hot air convection dryer at 75°C and 125°C to form a photosensitive layer with a thickness of 25 μm after drying. A polyethylene film (Tamapoly Corporation, product name "NF-15") (protective layer) was laminated onto this photosensitive layer to obtain photosensitive elements in which the support, photosensitive layer, and protective layer were laminated in this order.

[0092] [Evaluation of migration of photosensitizers into polyethylene films] The photosensitive element prepared above was wrapped in a black sheet and left to stand under yellow light for 24 hours, after which the polyethylene film was peeled off from the photosensitive element. The absorbance Abs(Sample) of the peeled polyethylene film at 405 nm was measured using an ultraviolet-visible spectrophotometer (Shimadzu Corporation (UV-1800)). Furthermore, the absorbance Abs(Ref) of a new polyethylene film identical to the polyethylene film used in preparing the photosensitive element described above was measured at 405 nm in the same manner as above. The presence or absence of migration was evaluated from the measured absorbance based on the following criteria: No migration: Abs(Sample)-Abs(Ref)<0.01 Migration: Abs(Sample)-Abs(Ref)≧0.01

[0093] [Laminate fabrication] A copper-clad laminate (manufactured by Showa Denko Materials Co., Ltd., product name "MCL-E-67") in which copper foil (thickness: 35 μm) was laminated on both sides of a glass fiber-reinforced epoxy resin layer was washed with water, pickled, and then washed with water, and then dried with an air flow. The copper-clad laminate was then heated to 80°C, and a photosensitive element was laminated on the copper surface of the copper-clad laminate. Lamination was performed using a heat roll at 110°C, while removing the protective layer, at a pressure of 0.4 MPa and a roll speed of 1.0 m / min. This resulted in a laminate in which the copper-clad laminate, photosensitive layer, and support were laminated in this order.

[0094] [Sensitivity evaluation] (Evaluation using a low-intensity light source) A 41-step step tablet (manufactured by Showa Denko Materials Co., Ltd.) was placed on the support of the obtained laminate, and a direct imaging exposure machine (Via Mechanics Co., Ltd. (DE-1UH), exposure wavelength 405 nm) was used to expose the laminate to 100 mJ / cm . 2 The exposure was carried out so that Next, the photosensitive layer was developed in a 1% by mass aqueous solution of sodium carbonate at 30°C, and the development time until no remaining film was observed was measured. Development was continued for twice the obtained development time, and the number of step tablets remaining on the substrate (ST step number) was evaluated. A larger ST step number indicates higher sensitivity. The results are shown in Table 1. Table 1 shows the relative values ​​when the ST step number of Comparative Example 2 is set to 1.0.

[0095] (Evaluation using a high-intensity light source) A direct exposure machine (Orbotech (Fine8), exposure wavelength 405 nm) was used as the exposure machine, and the exposure was performed at 40 mJ / cm 2 The sensitivity was evaluated in the same manner as in the evaluation using a low-intensity light source, except that the exposure was carried out so that the sensitivity was 100%.

[0096] [Adhesion evaluation] A pattern was written on the support of the laminate using a direct writing exposure machine (Via Mechanics Co., Ltd. (DE-1UH), exposure wavelength 405 nm) with an exposure dose equivalent to 16 ST steps. After development, the space portions (unexposed portions) were cleanly removed, and the line portions (exposed portions) were formed without meandering or chipping. Of the resist patterns, the dimension of the line portion: n (μm) in the isolated pattern where the ratio line portion (μm) / space portion (μm) = n (μm) / 400 (μm) was smallest was measured. The smaller this dimension, the higher the adhesion. The results are shown in Table 1.

[0097] [Absorbance of photosensitive element] The polyethylene film was peeled off from the prepared photosensitive element, and the absorbance at 405 nm was measured using an ultraviolet-visible spectrophotometer (Shimadzu Corporation (UV-1800)). The results are shown in Table 1.

[0098] [Table 1]

[0099] As can be seen from Table 1, when a hexaarylbiimidazole compound is used as a photopolymerization initiator and DBA or the like is used as a photosensitizer, migration to the polyethylene film occurs (Comparative Examples 1 and 2), whereas when a compound represented by formula (1) is used as a photosensitizer, migration to the polyethylene film is suppressed (Examples 1 to 7). On the other hand, when a compound other than a hexaarylbiimidazole compound is used as a photopolymerization initiator and a compound represented by formula (1) is used as a photosensitizer (Comparative Example 3), migration to the polyethylene film is suppressed, but sensitivity (particularly sensitivity when using a low-intensity light source) is inferior to when a hexaarylbiimidazole compound is used as a photopolymerization initiator and a compound represented by formula (1) is used as a photosensitizer (Examples 1 to 7). Furthermore, the photosensitive compositions containing a combination of a hexaarylbiimidazole compound and a compound represented by formula (1) (Examples 1 to 7) also exhibit excellent adhesion to substrates. [Explanation of symbols]

[0100] 1... photosensitive element, 2... support, 3, 13... photosensitive layer, 4... protective layer, 16... resist pattern, 17... wiring layer, 18... wiring board.

Claims

1. a photopolymerizable compound; a hexaarylbiimidazole compound; A photosensitive composition comprising a compound represented by the following formula (1): 【Chemical 1】 [In the formula, R １ , R ２ and R ３ each independently represents 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. R in the formula (1) １ , R ２ and R ３ The photosensitive composition according to claim 1 , wherein the number of carbon atoms in the alkyl group represented by the formula (I) is 2 or more.

3. 3. The photosensitive composition according to claim 1, wherein m and n in formula (1) are 0.

4. 3. The photosensitive composition according to claim 1, wherein m is 1 and n is 0 in formula (1).

5. 3. The photosensitive composition according to claim 1, wherein m is 0 and n is 1 in formula (1).

6. 3. The photosensitive composition according to claim 1, wherein m is 0 and n is 2 in formula (1).

7. 3. The photosensitive composition according to claim 1, wherein the compound represented by formula (1) is a compound represented by formula (6): 【Chemistry 2】 [In the formula, R １ and R ２ is R in the formula (1). １ and R ２ and R ４ represents a halogen atom.]

8. 8. The photosensitive composition of claim 7, wherein the halogen atom is a chlorine atom.

9. A support; a photosensitive layer provided on the support and comprising the photosensitive composition according to claim 1 or 2; A photosensitive element comprising:

10. providing a photosensitive layer made of the photosensitive composition according to claim 1 or 2 on a substrate; photocuring a portion of the photosensitive layer; removing uncured portions of the photosensitive layer to form a resist pattern; forming a wiring layer on a portion of the substrate where the resist pattern is not formed; A method for manufacturing a wiring board, comprising:

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