Photosensitive resin composition

Abstract

To provide a photosensitive resin composition etc. that can produce an optical waveguide having an excellent core formation property and low optical transmission loss.SOLUTION: Provided is a photosensitive resin composition that contains (A) an epoxy resin, (B) a resin containing a carboxyl group and an ethylenic double bond, (C) a photopolymerization initiator, and (D) a photosensitizer having a molecular weight of 400 or more.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a photosensitive resin composition, a resin sheet, a photosensitive resin composition set, an optical waveguide and a method for manufacturing the same, and a photoelectric hybrid substrate.

Background Art

[0002] Due to technological advancements such as 5G communication, autonomous driving, IoT, artificial intelligence, and big data, the demand for ultra-high-speed and high-capacity communication has been increasing. Conventionally, semiconductor packages that support the foundation of this have been coping with high-speed communication by flowing high-frequency currents. However, in recent years, problems such as noise generation, communication loss, and heat generation due to high-speed communication have become apparent. In order to solve these problems, efforts have been actively made in recent years to mount an optical circuit on an electrical wiring board to achieve energy saving, low latency, and high-speed communication (Patent Documents 1 and 2). [[ID=​​​​​​​​​​​​​​​​​​​​​​​​​​​​For example, in silicon photonics, it is expected that optical integrated circuits will be formed on chips using fine waveguides. When manufacturing an optoelectronic mixed-signal substrate on which such chips are mounted, it is necessary to provide optical waveguides on the optoelectronic mixed-signal substrate in order to extract signal light from the fine waveguides within the chip and connect it to the wiring between chips. From the viewpoint of efficiently forming fine optical waveguides, it is desirable to form the optical waveguides using a cured product of a photosensitive resin composition. For this reason, it is desirable that the material has excellent core-forming properties in order to form a fine core layer. Furthermore, in order to suppress the attenuation of signal light, it is also desirable to suppress the transmission loss of the optical waveguide.

[0006] The present invention was devised in view of the above-mentioned problems, and aims to provide a photosensitive resin composition that can manufacture optical waveguides with excellent core-forming properties and low transmission loss; a resin sheet containing the photosensitive resin composition; a set of photosensitive resin compositions; an optical waveguide; and a photoelectric mixed-signal substrate. [Means for solving the problem]

[0007] The inventors diligently studied to solve the aforementioned problems. As a result, the inventors discovered that by using a photosensitive resin composition containing a combination of (A) epoxy resin, (B) a resin containing a carboxyl group and an ethylenically double bond, (C) a photopolymerization initiator, and (D) a photosensitizer with a molecular weight of 400 or more, it is possible to manufacture an optical waveguide with excellent core-forming properties and low transmission loss, thus completing the present invention.

[0008] In other words, the present invention includes the following: [1] (A) epoxy resin, (B) Resins containing carboxyl groups and ethylenic double bonds, (C) Photopolymerization initiator, and (D) A photosensitive resin composition containing a photosensitizer with a molecular weight of 400 or more. [2] The photosensitive resin composition according to [1], wherein component (C) contains a photopolymerization initiator having a molecular weight of 420 or more. [3] The photosensitive resin composition according to [1] or [2], further comprising (E) an inorganic filler with an average particle size of 100 nm or less. [4] The photosensitive resin composition according to any one of [1] to [3], wherein component (D) contains a tertiary amino group in the molecule. [5] The photosensitive resin composition according to any one of [1] to [4], wherein component (D) contains an aminobenzoyl group in the molecule. [6] The photosensitive resin composition according to any one of [1] to [5], wherein component (A) contains either a naphthalene skeleton-containing epoxy resin or a biphenyl skeleton-containing epoxy resin. [7] A photosensitive resin composition according to any one of [1] to [6], for use in developing sodium carbonate. [8] A photosensitive resin composition according to any one of [1] to [7], for the manufacture of a core layer of an optical waveguide. [9] comprising a support and a photosensitive resin composition layer formed on the support, A resin sheet in which the photosensitive resin composition layer is made of the photosensitive resin composition described in any of [1] to [8].

[10] The resin sheet according to [9], wherein the thickness of the photosensitive resin composition layer is 1 μm or more and 15 μm or less.

[11] A photosensitive resin composition set comprising a core photosensitive resin composition and a cladding resin composition, A set of photosensitive resin compositions, wherein the core photosensitive resin composition includes the photosensitive resin composition described in any of [1] to [8].

[12] comprising a core layer and a cladding layer, An optical waveguide in which the core layer comprises a cured product of a photosensitive resin composition described in any of [1] to [8].

[13] The optical waveguide described in

[12] , capable of transmitting light with wavelengths of 1300 nm to 1320 nm.

[14] The optical waveguide described in

[12] or

[13] , which is a single-mode optical waveguide.

[15] An optoelectronic mixed-signal substrate equipped with an optical waveguide as described in any of

[12] to

[14] . [Effects of the Invention]

[0009] According to the present invention, a photosensitive resin composition capable of producing optical waveguides with excellent core-forming properties and low optical transmission loss; a set of photosensitive resin compositions containing the photosensitive resin composition; an optical waveguide; and a photoelectric mixed-signal substrate can be provided. [Brief explanation of the drawing]

[0010] [Figure 1] Figure 1 is a schematic perspective view showing an optical waveguide according to one embodiment of the present invention. [Figure 2] Figure 2 is a schematic cross-sectional view illustrating step (I) of a method for manufacturing an optical waveguide according to one embodiment of the present invention. [Figure 3] Figure 3 is a schematic cross-sectional view illustrating step (II) of the method for manufacturing an optical waveguide according to one embodiment of the present invention. [Figure 4] Figure 4 is a schematic cross-sectional view illustrating step (III) of the method for manufacturing an optical waveguide according to one embodiment of the present invention. [Figure 5] Figure 5 is a schematic cross-sectional view illustrating step (IV) of the method for manufacturing an optical waveguide according to one embodiment of the present invention. [Figure 6] Figure 6 is a schematic cross-sectional view illustrating step (V) of the method for manufacturing an optical waveguide according to one embodiment of the present invention. [Figure 7] Figure 7 is a schematic cross-sectional view illustrating step (VI) of the method for manufacturing an optical waveguide according to one embodiment of the present invention. [Figure 8] Figure 8 is a schematic cross-sectional view illustrating step (VII) of the method for manufacturing an optical waveguide according to one embodiment of the present invention. [Figure 9] Figure 9 is a schematic cross-sectional view illustrating step (VIII) of the method for manufacturing an optical waveguide according to one embodiment of the present invention. [Modes for carrying out the invention]

[0011] The present invention will be described in detail below with reference to embodiments and examples. However, the present invention is not limited to the embodiments and examples listed below, and may be implemented with modifications as appropriate without departing from the scope of the claims and their equivalents.

[0012] [Photosensitive resin composition] The photosensitive resin composition of the present invention contains (A) an epoxy resin, (B) a resin containing a carboxyl group and an ethylenically double bond, (C) a photopolymerization initiator, and (D) a photosensitizer with a molecular weight of 400 or more. According to the photosensitive resin composition of the present invention, it becomes possible to manufacture optical waveguides with excellent core-forming properties and low optical transmission loss. Furthermore, the present invention also makes it possible to obtain cured products with generally low optical transmission loss.

[0013] The photosensitive resin composition of the present invention may contain any additional components in combination with components (A) to (D). Examples of optional components include (E) an inorganic filler with an average particle size of 100 nm or less, (F) a reactive diluent, (G) a solvent, and (H) other additives. The components contained in the photosensitive resin composition will be described in detail below.

[0014] In the following explanation, unless otherwise specified, the term "(meth)acrylic acid" includes acrylic acid, methacrylic acid, and combinations thereof, and the term "(meth)acrylate" includes acrylate, methacrylate, and combinations thereof.

[0015] Furthermore, in the present invention, unless otherwise specified, the content of each component in the photosensitive resin composition is the value when the non-volatile component in the photosensitive resin composition is taken as 100% by mass.

[0016] <(A) Epoxy resin> The photosensitive resin composition contains (A) epoxy resin as component (A). (A) epoxy resin is a curable resin having epoxy groups.

[0017] (A) Examples of epoxy resins include bixylenol-type epoxy resins; bisphenol-type epoxy resins such as bisphenol A-type epoxy resin, bisphenol F-type epoxy resin, bisphenol S-type epoxy resin, and bisphenol AF-type epoxy resin; dicyclopentadiene-type epoxy resins; novolac-type epoxy resins such as trisphenol-type epoxy resin and phenol novolac-type epoxy resin; tert-butyl-catechol-type epoxy resins; and naphthalene-backbone-containing epoxy resins such as naphthalene-type epoxy resin, naphthol-type epoxy resin, naphthylene ether-type epoxy resin, and naphthol novolac-type epoxy resin. Examples of epoxy resins include: anthracene-type epoxy resins, glycidylamine-type epoxy resins, glycidyl ester-type epoxy resins, cresol novolac-type epoxy resins, phenol aralkyl-type epoxy resins, biphenyl skeleton-containing epoxy resins, linear aliphatic epoxy resins, epoxy resins having a butadiene structure, alicyclic epoxy resins, heterocyclic epoxy resins, spiro-ring-containing epoxy resins, cyclohexane-type epoxy resins, cyclohexanedimethanol-type epoxy resins, trimethylol-type epoxy resins, tetraphenylethane-type epoxy resins, isocyanurate-type epoxy resins, phenolphthaleimidine-type epoxy resins, etc. Among these, (A) epoxy resin is preferably a dicyclopentadiene-type epoxy resin, a naphthalene-type epoxy resin, and a cresol novolac-type epoxy resin, from the viewpoint of obtaining the effects of the present invention in particular. (A) epoxy resin may be used alone or in combination of two or more types.

[0018] The photosensitive resin composition of the present invention preferably contains an epoxy resin having two or more epoxy groups in one molecule as (A) epoxy resin. The proportion of the epoxy resin having two or more epoxy groups in one molecule to 100% by mass of (A) epoxy resin is preferably 50% by mass or more, more preferably 60% by mass or more, and particularly preferably 70% by mass or more.

[0019] (A) Epoxy resins include epoxy resins that are solid at 20°C (hereinafter sometimes referred to as "solid epoxy resins") and epoxy resins that are liquid at 20°C (hereinafter sometimes referred to as "liquid epoxy resins"). The photosensitive resin composition of the present invention may contain only liquid epoxy resin, only solid epoxy resin, or both liquid epoxy resin and solid epoxy resin as (A) epoxy resin, but it is particularly preferable to contain only solid epoxy resin.

[0020] As the solid epoxy resin, a solid epoxy resin having three or more epoxy groups per molecule is preferred, and an aromatic solid epoxy resin having three or more epoxy groups per molecule is more preferred.

[0021] As solid epoxy resins, bixylenol-type epoxy resins, naphthalene-type epoxy resins, naphthalene-type tetrafunctional epoxy resins, naphthol novolac-type epoxy resins, cresol novolac-type epoxy resins, dicyclopentadiene-type epoxy resins, trisphenol-type epoxy resins, naphthol-type epoxy resins, biphenyl-type epoxy resins, naphthylene ether-type epoxy resins, anthracene-type epoxy resins, bisphenol A-type epoxy resins, bisphenol AF-type epoxy resins, phenol aralkyl-type epoxy resins, tetraphenylethane-type epoxy resins, and phenolphthaleimidine-type epoxy resins are preferred, with naphthalene skeleton-containing epoxy resins and biphenyl skeleton-containing epoxy resins being more preferred, and dicyclopentadiene-type epoxy resins, naphthalene-type epoxy resins, and cresol novolac-type epoxy resins being even more preferred.

[0022] Specific examples of solid epoxy resins include DIC's "HP4032H" (naphthalene-type epoxy resin); DIC's "HP-4700" and "HP-4710" (naphthalene-type tetrafunctional epoxy resins); DIC's "N-690" (cresol novolac-type epoxy resin); DIC's "N-695" (cresol novolac-type epoxy resin); DIC's "N-673" (cresol novolac-type epoxy resin); DIC's "HP-7200", "HP-7200HH", "HP-7200H", and "HP-7200L". (Dicyclopentadiene type epoxy resin); "EXA-7311", "EXA-7311-G3", "EXA-7311-G4", "EXA-7311-G4S", "HP6000" manufactured by DIC Corporation (Naphthylene ether type epoxy resin); "EPPN-502H" manufactured by Nippon Kayaku Co., Ltd. (Trisphenol type epoxy resin); "NC7000L" manufactured by Nippon Kayaku Co., Ltd. (Naphthol novolac type epoxy resin); "NC3000H", "NC3000", "NC3000L", "NC3000FH", "NC3100" manufactured by Nippon Kayaku Co., Ltd. (Biphenyl Epoxy resins; "ESN475V" and "ESN4100V" (naphthalene-type epoxy resins) manufactured by Nippon Steel Chemical & Material Co., Ltd.; "ESN485" (naphthol-type epoxy resin) manufactured by Nippon Steel Chemical & Material Co., Ltd.; "ESN375" (dihydroxynaphthalene-type epoxy resin) manufactured by Nippon Steel Chemical & Material Co., Ltd.; "YX4000H", "YX4000", "YX4000HK", and "YL7890" (bixylenol-type epoxy resins) manufactured by Mitsubishi Chemical Corporation; "YL6121" (biphenyl-type epoxy resin) manufactured by Mitsubishi Chemical Corporation; Mitsubishi "YX8800" (anthracene-type epoxy resin) manufactured by Chemical Co., Ltd.; "YX7700" (phenol aralkyl-type epoxy resin) manufactured by Mitsubishi Chemical Corporation; "PG-100" and "CG-500" manufactured by Osaka Gas Chemical Co., Ltd.; "YL7760" (bisphenol AF-type epoxy resin) manufactured by Mitsubishi Chemical Corporation; "YL7800" (fluorene-type epoxy resin) manufactured by Mitsubishi Chemical Corporation; "jER1010" (bisphenol A-type epoxy resin) manufactured by Mitsubishi Chemical Corporation; "jER1031S" (tetraphenylethane-type epoxy resin) manufactured by Mitsubishi Chemical Corporation;Examples include "WHR991S" (phenolphthaleimidine-type epoxy resin) manufactured by Nippon Kayaku Co., Ltd. These can be used individually or in combination of two or more types.

[0023] As the liquid epoxy resin, a liquid epoxy resin having two or more epoxy groups in one molecule is preferred.

[0024] Preferred liquid epoxy resins include glycirol-type epoxy resins, bisphenol A-type epoxy resins, bisphenol F-type epoxy resins, bisphenol AF-type epoxy resins, naphthalene-type epoxy resins, glycidyl ester-type epoxy resins, glycidylamine-type epoxy resins, phenol novolac-type epoxy resins, alicyclic epoxy resins having an ester skeleton, cyclohexanedimethanol-type epoxy resins, cyclic aliphatic glycidyl ethers, and epoxy resins having a butadiene structure.

[0025] Specific examples of liquid epoxy resins include "EX-992L" from Nagase ChemteX, "YX7400" from Mitsubishi Chemical Corporation, "HP4032", "HP4032D", and "HP4032SS" (naphthalene-type epoxy resin) from DIC Corporation; "828US", "jER828EL", "828EL", "825", and "Epicote 828EL" (bisphenol A-type epoxy resin) from Mitsubishi Chemical Corporation; and "jER807" and "1750" from Mitsubishi Chemical Corporation. Bisphenol F type epoxy resin; "jER152" (phenol novolac type epoxy resin) manufactured by Mitsubishi Chemical Corporation; "630", "630LSD", "604" (glycidylamine type epoxy resin) manufactured by Mitsubishi Chemical Corporation; "ED-523T" (glycyrol type epoxy resin) manufactured by ADEKA Corporation; "EP-3950L", "EP-3980S" (glycidylamine type epoxy resin) manufactured by ADEKA Corporation; "EP-4088S" (dicyclopentadiene type epoxy resin) manufactured by ADEKA Corporation; "ZX1059" (mixture of bisphenol A type epoxy resin and bisphenol F type epoxy resin) manufactured by Nippon Steel Chemical & Material Corporation; "EX-721" (glycidyl ester type epoxy resin) manufactured by Nagase ChemteX Corporation; "EX-991L" (epoxy resin containing alkylene oxy skeleton and butadiene skeleton) manufactured by Nagase ChemteX Corporation; "Celoxide 2021P" (alicyclic epoxy resin with ester skeleton) manufactured by Daicel Corporation Examples include "PB-3600" from Daicel Corporation, "JP-100" and "JP-200" from Nippon Soda Co., Ltd. (epoxy resins with a butadiene structure); "ZX1658" and "ZX1658GS" from Nippon Steel Chemical & Material Co., Ltd. (liquid 1,4-glycidylcyclohexane type epoxy resins); "EG-280" from Osaka Gas Chemical Co., Ltd. (fluorene structure-containing epoxy resin); and "EX-201" from Nagase ChemteX Corporation (cyclic aliphatic glycidyl ether).

[0026] (A) When using a combination of solid epoxy resin and liquid epoxy resin as the epoxy resin, the mass ratio of the solid epoxy resin to the liquid epoxy resin is preferably 10:1 to 1:50, more preferably 5:1 to 1:20, and particularly preferably 2:1 to 1:10.

[0027] (A) The epoxy resin preferably includes an epoxy resin having a skeleton selected from a naphthalene skeleton and a biphenyl skeleton, and is particularly preferably an epoxy resin having a naphthalene skeleton.

[0028] (A) The epoxy equivalent of the epoxy resin is preferably 50 g / eq. to 5,000 g / eq., more preferably 60 g / eq. to 2,000 g / eq., even more preferably 70 g / eq. to 1,000 g / eq., and even more preferably 80 g / eq. to 500 g / eq. The epoxy equivalent is the mass of resin per equivalent of epoxy groups. This epoxy equivalent can be measured according to JIS K7236.

[0029] (A) The weight-average molecular weight (Mw) of the epoxy resin is preferably 100 to 5,000, more preferably 250 to 3,000, and even more preferably 400 to 1,500. The weight-average molecular weight of the resin can be measured as a polystyrene equivalent by gel permeation chromatography (GPC).

[0030] (A) The epoxy resin content is preferably 5% by mass or more, more preferably 10% by mass or more, even more preferably 15% by mass or more, preferably 40% by mass or less, more preferably 35% by mass or less, and even more preferably 30% by mass or less, when the nonvolatile components of the photosensitive resin composition are considered to be 100% by mass, from the viewpoint of further improving mechanical strength and insulation reliability.

[0031] <(B) Resins containing carboxyl groups and ethylenic double bonds> The photosensitive resin composition of the present invention contains a resin containing a carboxyl group and an ethylenically double bond as component (B). This resin containing a carboxyl group and an ethylenically double bond as component (B) does not include any of the components (A) described above. Component (B) may be used alone or in combination of two or more types.

[0032] (B) The resin containing a carboxyl group and an ethylenically double bond contains an acidic carboxyl group, and therefore the photosensitive resin composition of the present invention may be soluble in an alkaline developer such as a 1% by mass aqueous solution of sodium carbonate. (B) In the resin containing a carboxyl group and an ethylenically double bond, the number of carboxyl groups in one molecule may be one or two or more.

[0033] (B) Resins containing carboxyl groups and ethylenic double bonds contain ethylenic double bonds as aliphatic carbon-carbon unsaturated bonds. Therefore, (B) resins containing carboxyl groups and ethylenic double bonds can undergo polymerization when (C) a photopolymerization initiator generates radicals.

[0034] (B) Resins containing a carboxyl group and an ethylenically double bond typically have a group containing the aforementioned ethylenically double bond. This group generally exhibits radical polymerization properties and is therefore sometimes referred to as a "radical polymerizable group." Examples of radical polymerizable groups include (meth)acryloyl group (acryloyl group or methacryloyl group), vinyl group, allyl group, propagyl group, butenyl group, ethynyl group, phenylethynyl group, maleimide group, nadiimide group, etc., and from the viewpoint of reactivity in radical polymerization, the (meth)acryloyl group is preferred.

[0035] (B) The number of radical polymerizable groups per molecule of the resin containing a carboxyl group and an ethylenic double bond may be one or two or more.

[0036] (B) In one embodiment, the resin containing the carboxyl group and the ethylenic double bond is preferably an acid-modified epoxy (meth)acrylate resin.

[0037] Since the acid-modified epoxy (meth)acrylate resin has (meth)acryloyl groups, in one embodiment, photoradical polymerization may be possible. The number of (meth)acryloyl groups per molecule of the acid-modified epoxy (meth)acrylate resin may be one or two or more.

[0038] The acid-modified epoxy (meth)acrylate resin is preferably a resin that has both (meth)acryloyl groups and carboxyl groups, and that enables photoradical polymerization and alkaline development.

[0039] Acid-modified epoxy (meth)acrylate resins can be produced by acid-modifying epoxy (meth)acrylate resins using known methods. For example, epoxy (meth)acrylate resins can be produced by reacting epoxy resin with acrylic acid or methacrylic acid.

[0040] The epoxy resin used for the production of epoxy (meth)acrylate resins is not particularly limited as long as it is a compound having an epoxy group in its molecule. Examples include bisphenol type epoxy resins such as bisphenol A type epoxy resin, hydrogenated bisphenol A type epoxy resin, bisphenol F type epoxy resin, hydrogenated bisphenol F type epoxy resin, bisphenol S type epoxy resin, and modified bisphenol F type epoxy resin obtained by reacting bisphenol F type epoxy resin with epichlorohydrin to modify it into a trifunctional or more complex resin; biphenol type epoxy resins such as biphenol type epoxy resin and tetramethylbiphenol type epoxy resin; novolac type epoxy resins such as phenol novolac type epoxy resin, cresol novolac type epoxy resin, bisphenol A type novolac type epoxy resin, and alkylphenol novolac type epoxy resin; fluorine-containing epoxy resins such as bisphenol AF type epoxy resin and perfluoroalkyl type epoxy resin; naphthalene type epoxy resin, dihydroxynaphthalene type epoxy resin, polyhydroxybinaphthalene type epoxy resin, naphthol type epoxy resin, and naphthol aralkyl type epoxy resin. Epoxy resins containing a naphthalene skeleton, such as lipids, binaphthol-type epoxy resins, naphthylene ether-type epoxy resins, naphthol novolac-type epoxy resins, and naphthalene-type epoxy resins obtained by the condensation reaction of polyhydroxynaphthalene and aldehydes (naphthalene skeleton-containing epoxy resins); bixylenol-type epoxy resins; dicyclopentadiene-type epoxy resins; trisphenol-type epoxy resins; tert-butyl-catechol-type epoxy resins; anthracene-type epoxy resins; and glycidylamine-type epoxy resins. Examples include epoxy resins; glycidyl ester type epoxy resins; biphenyl type epoxy resins; linear aliphatic epoxy resins; epoxy resins having a butadiene structure; alicyclic epoxy resins; heterocyclic epoxy resins; spiroring-containing epoxy resins; cyclohexanedimethanol type epoxy resins; trimethylol type epoxy resins; tetraphenylethane type epoxy resins; glycidyl group-containing acrylic resins such as polyglycidyl (meth)acrylate and copolymers of glycidyl methacrylate and acrylic acid esters; fluorene type epoxy resins; halogenated epoxy resins, etc.

[0041] For the production of epoxy (meth)acrylate resins, epoxy resins containing an aromatic skeleton are preferred from the viewpoint of significantly obtaining the effects of the present invention. Here, the term "aromatic skeleton" is a concept that includes polycyclic aromatics and aromatic heterocyclics. Among these, any of cresol novolac type epoxy resins, bisphenol A type epoxy resins, bisphenol F type epoxy resins, biphenyl type epoxy resins, and naphthol aralkyl type epoxy resins are preferred, with naphthol aralkyl type epoxy resins being more preferred.

[0042] In one embodiment, the acid-modified epoxy (meth)acrylate resin preferably includes an acid-modified epoxy (meth)acrylate resin having a skeleton selected from a naphthol aralkyl skeleton, a naphthalene skeleton, and a biphenyl skeleton, and is particularly preferably an acid-modified epoxy (meth)acrylate resin having a naphthol aralkyl skeleton.

[0043] In one embodiment, the acid-modified epoxy (meth)acrylate resin preferably includes a resin selected from an acid-modified epoxy (meth)acrylate resin in which the hydroxyl groups of the epoxy (meth)acrylate resin are esterified (hereinafter referred to as "ester-type acid-modified epoxy (meth)acrylate resin") and an acid-modified epoxy (meth)acrylate resin in which the hydroxyl groups of the epoxy (meth)acrylate resin are urethane-modified (hereinafter referred to as "urethane-type acid-modified epoxy (meth)acrylate resin"), and it is particularly preferable that it includes an ester-type acid-modified epoxy (meth)acrylate resin.

[0044] Ester-type acid-modified epoxy (meth)acrylate resins can be produced, for example, by reacting epoxy (meth)acrylate resin with a polycarboxylic acid anhydride. Ester-type acid-modified epoxy (meth)acrylate resins may be used individually or in combination of two or more types.

[0045] Examples of polycarboxylic acid anhydrides include maleic anhydride, succinic anhydride, itaconic anhydride, phthalic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, trimellitic anhydride, pyromellitic anhydride, and benzophenonetetracarboxylic dianhydride. These may be used individually or in combination of two or more. Among these, succinic anhydride and tetrahydrophthalic anhydride are preferred, with tetrahydrophthalic anhydride being more preferred.

[0046] The ester-type acid-modified epoxy (meth)acrylate resin preferably includes a resin selected from cresol novolac skeleton-containing ester-type acid-modified epoxy (meth)acrylate resin, bisphenol A skeleton-containing ester-type acid-modified epoxy (meth)acrylate resin, bisphenol F skeleton-containing ester-type acid-modified epoxy (meth)acrylate resin, biphenyl skeleton-containing acid ester-type modified epoxy (meth)acrylate resin, and naphthol aralkyl skeleton-containing ester-type acid-modified epoxy (meth)acrylate resin.

[0047] Ester-type acid-modified epoxy (meth)acrylate resins can be synthesized by known methods, but commercially available products may also be used. Specific examples of commercially available products include Nippon Kayaku Co., Ltd.'s "CCR-1373H" (cresol novolac skeleton-containing acid-modified epoxy acrylate resin), "ZCR-8001H" (biphenyl skeleton-containing acid-modified epoxy acrylate resin), "ZCR-1569H" (biphenyl skeleton-containing acid-modified epoxy acrylate resin), "CCR-1171H" (cresol novolac skeleton-containing acid-modified epoxy acrylate resin), and "ZCR-1797H" (biphenyl skeleton-containing acid-modified epoxy acrylate resin). Examples of acrylate resins include "ZAR-2000" (bisphenol A skeleton-containing acid-modified epoxy acrylate resin), "ZFR-1491H", and "ZFR-1533H" (bisphenol F skeleton-containing acid-modified epoxy acrylate resins) from Nippon Kayaku Co., Ltd., "PR-300CP" (cresol novolac type acid-modified epoxy acrylate resin) from Showa Denko Corporation, and "CCR-1179" (cresol novolac skeleton-containing epoxy acrylate resin) from Nippon Kayaku Co., Ltd.

[0048] Urethane-type acid-modified epoxy (meth)acrylate resins can be produced, for example, by reacting epoxy (meth)acrylate resin with a diisocyanate compound and a carboxyl group-containing diol compound. Urethane-type acid-modified epoxy (meth)acrylate resins may be used individually or in combination of two or more types.

[0049] Examples of diisocyanate compounds include aromatic diisocyanate compounds such as phenylenediisocyanate, tolylenediisocyanate, xylylenediisocyanate, tetramethylxylylenediisocyanate, diphenyldiisocyanate, and naphthalenediisocyanate; and aliphatic diisocyanate compounds such as hexamethylenediisocyanate, dicyclohexylmethanediisocyanate, isophoronediisocyanate, allylenesulfone etherdiisocyanate, allylcyanidediisocyanate, N-acyldiisocyanate, trimethylhexamethylenediisocyanate, and 1,3-bis(isocyanatemethyl)cyclohexane.

[0050] Examples of carboxyl group-containing diol compounds include dimethylolpropionic acid, dimethylolbutanoic acid, and dimethylolnonanoic acid.

[0051] The urethane-type acid-modified epoxy (meth)acrylate resin preferably contains a resin selected from cresol novolac skeleton-containing urethane-type acid-modified epoxy (meth)acrylate resin, bisphenol A skeleton-containing urethane-type acid-modified epoxy (meth)acrylate resin, bisphenol F skeleton-containing urethane-type acid-modified epoxy (meth)acrylate resin, biphenyl skeleton-containing acid urethane-type modified epoxy (meth)acrylate resin, and naphthol aralkyl skeleton-containing urethane-type acid-modified epoxy (meth)acrylate resin.

[0052] Urethane-type acid-modified epoxy (meth)acrylate resins can be synthesized by known synthesis methods, but commercially available products may also be used. Examples of known synthesis methods include the method described in Japanese Patent Publication No. 2016-199719. Specific examples of commercially available products include "UXE-3024," "UXE-3011," "UXE-3012," and "UXE-3024" manufactured by Nippon Kayaku Co., Ltd.

[0053] The acid value of component (B) is preferably 0.1 mg KOH / g or more, more preferably 0.5 mg KOH / g or more, even more preferably 1 mg KOH / g or more, 10 mg KOH / g or more, even more preferably 20 mg KOH / g or more, 30 mg KOH / g or more, and particularly preferably 40 mg KOH / g or more, 50 mg KOH / g or more, from the viewpoint of improving the alkali developability of the photosensitive resin composition. The upper limit of the acid value of component (B) is preferably 200 mg KOH / g or less, more preferably 150 mg KOH / g or less, even more preferably 120 mg KOH / g or less, and particularly preferably 100 mg KOH / g or less.

[0054] The weight-average molecular weight of component (B) is preferably 20,000 or less, more preferably 17,000 or less, even more preferably 15,000 or less, preferably 1,000 or more, and more preferably 1,500 or more. The weight-average molecular weight is the weight-average molecular weight on a polystyrene basis measured by gel permeation chromatography (GPC).

[0055] (B) The content of component (B), when the nonvolatile components of the photosensitive resin composition are considered to be 100% by mass, is preferably 15% by mass or more, more preferably 25% by mass or more, even more preferably 30% by mass or more, preferably 55% by mass or less, even more preferably 50% by mass or less, and particularly preferably 45% by mass or less.

[0056] The mass ratio of component (B) to epoxy resin (A) (mass of component (B) when the non-volatile components of the photosensitive resin composition are set to 100% by mass (mass%) / mass of component (A) when the non-volatile components of the photosensitive resin composition are set to 100% by mass (mass%)) is preferably 0.1 or more, more preferably 0.5 or more, and even more preferably 1 or more. The upper limit is preferably 10 or less, more preferably 5 or less, and even more preferably 3 or less.

[0057] <(C) Photopolymerization initiator> The photosensitive resin composition of the present invention contains a photopolymerization initiator as component (C). The photopolymerization initiator (C) can normally generate radicals upon receiving light. In addition, the photopolymerization initiator (C) can normally generate radicals by receiving energy from an excited photosensitizer (D). This photopolymerization initiator (C) as component (C) does not include those corresponding to components (A) and (B) described above. Component (C) may be used alone or in combination of two or more types.

[0058] As component (C), a photopolymerization initiator that can efficiently photocur the photosensitive resin composition can be used. Preferably, such a photopolymerization initiator contains either (C1) a photopolymerization initiator with a molecular weight of 420 or more, or (C2) a photopolymerization initiator with a molecular weight of less than 420. Component (C1) and component (C2) may be used in combination, but from the viewpoint of significantly obtaining the effects of the present invention, component (C) preferably contains either component (C1) or component (C2), and more preferably contains component (C1).

[0059] -(C1) Photopolymerization initiator with a molecular weight of 420 or more- The molecular weight of component (C1) is typically 420 or higher, preferably 500 or higher, more preferably 600 or higher, or 700 or higher, from the viewpoint of being able to form a fine core layer and manufacture an optical waveguide with low optical transmission loss. The upper limit is not particularly limited, but is preferably 3000 or lower, more preferably 2500 or lower, and even more preferably 2000 or lower.

[0060] As the (C1) component, a compound can be used that has a molecular weight of 420 or more, has a group that absorbs active light such as ultraviolet light, and can efficiently carry out photopolymerization. For example, such a (C1) component is preferably a compound that contains a structural unit represented by formula (C-1). [ka] (In the formula, R 1 represents an active light-absorbing group, R 2 Each of these independently represents a divalent hydrocarbon group. n represents an integer from 1 to 10. * represents a bond.

[0061] R 1 The symbol represents an active light-absorbing group. An active light-absorbing group is a group that can absorb active light such as ultraviolet light. Any functional group that can absorb active light can be an active light-absorbing group, and examples include groups having an aminoketone skeleton, an anthraquinone skeleton, a thioxanthone skeleton, a ketal skeleton, a benzophenone skeleton, a xanthone skeleton, an acetophenone skeleton, a benzoin skeleton, a thioxanthone skeleton, a benzoate skeleton, and so on.

[0062] Specific examples of active light-absorbing groups include the following groups (i) to (vii). Among these, (i) and (ii) are preferred as active light-absorbing groups. * represents a bond in the formula. [ka]

[0063] R 2 Each of these independently represents a divalent hydrocarbon group. Examples of divalent hydrocarbon groups include divalent aliphatic hydrocarbon groups and divalent aromatic hydrocarbon groups, and from the viewpoint of significantly obtaining the effects of the present invention, divalent aliphatic hydrocarbon groups are preferred.

[0064] As the divalent aliphatic hydrocarbon group, a divalent saturated aliphatic hydrocarbon group is preferred, such as an alkylene group or an alkenylene group, with the alkylene group being more preferred. The alkylene group may be linear, branched, or cyclic, with the linear form being preferred. As the alkylene group, an alkylene group having 1 to 10 carbon atoms is preferred, an alkylene group having 1 to 6 carbon atoms is more preferred, an alkylene group having 1 to 5 carbon atoms, or an alkylene group having 1 to 3 carbon atoms is even more preferred. Examples of such alkylene groups include a methylene group, an ethylene group, a propylene group, a butylene group, a pentylene group, a hexylene group, a cyclohexylene group, and the methylene group is preferred. The alkenylene group may be linear, branched, or cyclic, with the linear form being preferred. As for the alkenylene group, an alkenylene group having 2 to 10 carbon atoms is preferred, an alkenylene group having 2 to 6 carbon atoms is more preferred, and an alkenylene group having 2 to 5 carbon atoms is even more preferred.

[0065] Examples of divalent aromatic hydrocarbon groups include arylene groups and heteroarylene groups. Preferably, the arylene or heteroarylene groups have 6 to 20 carbon atoms, and more preferably, arylene or heteroarylene groups have 6 to 10 carbon atoms.

[0066] The divalent hydrocarbon group may have substituents. Examples of substituents include halogen atoms, alkyl groups, alkoxy groups, aryl groups, arylalkyl groups, silyl groups, acyl groups, acyloxy groups, carboxyl groups, sulfo groups, cyano groups, nitro groups, hydroxyl groups, mercapto groups, and oxo groups.

[0067] n represents an integer between 1 and 10, preferably between 1 and 8, more preferably between 1 and 5, and even more preferably between 1 and 3.

[0068] Component (C1) preferably contains either a compound represented by the following general formula (C-2) or a compound represented by the following general formula (C-3). [ka] (In general formula (C-2), R 11 each independently represents an actinic ray absorbing group, R 12 each independently represents a divalent hydrocarbon group, and R 13 represents a hydrocarbon group having a valence of m. n1 represents an integer of 1 to 10, and m represents an integer of 1 to 4.) In general formula (C-3), R 21 , R 23 each independently represents an actinic ray absorbing group, and R 22 each independently represents a divalent hydrocarbon group. n2 represents an integer of 1 to 10.)

[0069] R 11 each independently represents an actinic ray absorbing group, and is the same as the actinic ray absorbing group represented by R 1 in formula (C-1).

[0070] R 12 each independently represents a divalent hydrocarbon group, and is the same as the divalent hydrocarbon group represented by R 2 in formula (C-1).

[0071] R 13 represents a hydrocarbon group having a valence of m. Examples of the hydrocarbon group having a valence of m include a hydrocarbon group having a valence of m and an aromatic hydrocarbon group having a valence of m, and a hydrocarbon group having a valence of m is preferred. For example, when m is 3, a trivalent group obtained by removing three hydrogen atoms from an alkane is preferred. Specific examples of the group represented by R 13 include, for example, those shown below. In the formula, "*" represents a bond.) [Chemical formula]

[0072] n1 represents an integer of 1 to 10 and is the same as n in formula (C-1).

[0073] m represents an integer of 1 to 4, an integer of 1 to 3 is preferred, and 3 is more preferred.)

[0074] R 21 and R23 Each of these independently represents an active light-absorbing group, and R in formula (C-1) 1 This is the same as the active light-absorbing group represented by .

[0075] R 22 Each of these independently represents a divalent hydrocarbon group, and in formula (C-1) R 2 This is the same as the divalent hydrocarbon group represented by .

[0076] The following compounds are specific examples of the (C1) component. However, the (C1) component is not limited to these specific examples. a, b, c, and d each represent an integer from 1 to 10. [ka]

[0077] (C1) Component can be a commercially available product. Examples of commercially available products include IGM's "Omnipol910," "OmnipolTP," and "Omnipol9210."

[0078] As for the content of component (C1), from the viewpoint of significantly obtaining the effects of the present invention, when the nonvolatile component of the photosensitive resin composition is taken as 100% by mass, it is preferably 0.05% by mass or more, more preferably 0.1% by mass or more, even more preferably 1% by mass or more, preferably 15% by mass or less, more preferably 13% by mass or less, and even more preferably 10% by mass or less.

[0079] The mass ratio of component (C1) to epoxy resin (A) (mass of component (C1) when the nonvolatile components of the photosensitive resin composition are set to 100% by mass (mass%) / mass of component (A) when the nonvolatile components of the photosensitive resin composition are set to 100% by mass (mass%)) is preferably 0.001 or more, more preferably 0.005 or more, and even more preferably 0.01 or more, from the viewpoint of significantly obtaining the effects of the present invention. The upper limit is preferably 1 or less, more preferably 0.5 or less, and even more preferably 0.3 or less.

[0080] The mass ratio of component (C1) to the resin containing a carboxyl group and an ethylenically double bond (mass %) of component (C1) when the nonvolatile components of the photosensitive resin composition are set to 100% by mass / mass %) of component (B) when the nonvolatile components of the photosensitive resin composition are set to 100% by mass is preferably 0.001 or more, more preferably 0.002 or more, and even more preferably 0.01 or more, from the viewpoint of significantly obtaining the effects of the present invention. The upper limit is preferably 1 or less, more preferably 0.5 or less, and even more preferably 0.1 or less.

[0081] -(C2) Photopolymerization initiator with a molecular weight of less than 420- The molecular weight of component (C2) is less than 420, preferably 418 or less, and more preferably 415 or less, from the viewpoint of significantly obtaining the effects of the present invention. The lower limit is not particularly limited, but is preferably 100 or more, more preferably 200 or more, and even more preferably 300 or more.

[0082] Examples of the (C2) component include oxime ester-based photopolymerization initiators, α-aminoketone-based photopolymerization initiators, phosphine oxide-based photopolymerization initiators, α-hydroxyketone-based photopolymerization initiators, benzoin-based photopolymerization initiators, benzylketal-based photopolymerization initiators, acylphosphine-based photopolymerization initiators, and the like.

[0083] Examples of oxime ester-based photopolymerization initiators include 2-(benzoyloxyimino)-1-[4-(phenylthio)phenyl]octan-1-one (OXE01), [1-[9-ethyl-6-(2-methylbenzoyl)carbazole-3-yl]ethylideneamino]acetate (OXE02), ethanone, 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazole-3-yl]-,1-(O-acetyloxime), and the like.

[0084] Examples of α-aminoketone-based photopolymerization initiators include 2-methyl-1-phenyl-2-morpholinopropan-1-one, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one, 2-methyl-1-(4-hexylphenyl)-2-morpholinopropan-1-one, 2-ethyl-2-(dimethylamino)-1-(4-morpholinophenyl)butan-1-one, 2-benzyl-2-(dimethylamino)-1-(4-morpholinophenyl)butan-1-one, 2-(dimethylamino)-2-(4-methylphenylmethyl)-1-(4-morpholinophenyl)butan-1-one, and 2-methyl-1-(9,9-dibutylfluoren-2-yl)-2-morpholinopropan-1-one.

[0085] Examples of phosphine oxide-based photopolymerization initiators include bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, (2,4,6-trimethylbenzoyl)diphenylphosphine oxide, and polyoxyethylene glycerin ether tris[phenyl(2,4,6-trimethylbenzoyl)phosphine] (Polymeric TPO-L).

[0086] Examples of α-hydroxyketone-based photopolymerization initiators include 1-hydroxycyclohexylphenyl ketone, 2-hydroxy-2-methyl-1-phenylpropanone, 1-[4-(2-hydroxyethoxy)phenyl]-2-hydroxy-2-methylpropanone, and 2-hydroxy-1-{4-[4-(2-hydroxy-2-methylpropionyl)benzyl]phenyl}-2-methylpropan-1-one.

[0087] Examples of benzoin-based photopolymerization initiators include benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, and benzoin isobutyl ether. Examples of benzyl ketal-based photopolymerization initiators include 2,2-dimethoxy-2-phenylacetophenone.

[0088] Examples of acylphosphine-based photopolymerization initiators include bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide.

[0089] In one embodiment, component (C2) preferably contains any of the following, from the viewpoint of significantly obtaining the effects of the present invention: an oxime ester-based photopolymerization initiator, an α-aminoketone-based photopolymerization initiator, and an acylphosphine-based photopolymerization initiator.

[0090] (C2) Component can be a commercially available product. Specific examples of commercially available (C2) components include "Omnirad907", "Omnirad369", "Omnirad379", "Omnirad379EG", "Omnirad819", and "OmniradTPO" from IGM, "IrgacureTPO", "IrgacureOXE-01", and "IrgacureOXE-02" from BASF, and "N-1919" from ADEKA.

[0091] From the viewpoint of significantly obtaining the effects of the present invention, the content of component (C2) is preferably 0.05% by mass or more, more preferably 0.1% by mass or more, even more preferably 1% by mass or more, preferably 15% by mass or less, more preferably 13% by mass or less, and even more preferably 10% by mass or less, when the nonvolatile components of the photosensitive resin composition are taken as 100% by mass.

[0092] The mass ratio of component (C2) to epoxy resin (A) (mass of component (C2) when the nonvolatile components of the photosensitive resin composition are set to 100% by mass (mass%) / mass of component (A) when the nonvolatile components of the photosensitive resin composition are set to 100% by mass (mass%)) is preferably 0.001 or more, more preferably 0.005 or more, and even more preferably 0.01 or more, from the viewpoint of significantly obtaining the effects of the present invention. The upper limit is preferably 1 or less, more preferably 0.5 or less, and even more preferably 0.3 or less.

[0093] The mass ratio of component (C2) to the resin containing the carboxyl group and ethylenically double bond (mass of component (C2) when the nonvolatile components of the photosensitive resin composition are set to 100% by mass (mass%) / mass of component (B) when the nonvolatile components of the photosensitive resin composition are set to 100% by mass (mass%)) is preferably 0.001 or more, more preferably 0.002 or more, and even more preferably 0.01 or more, from the viewpoint of significantly obtaining the effects of the present invention. The upper limit is preferably 1 or less, more preferably 0.5 or less, and even more preferably 0.1 or less.

[0094] As for the content of component (C) (total content of components (C1) and (C2)), from the viewpoint of significantly obtaining the effects of the present invention, when the nonvolatile components of the photosensitive resin composition are taken as 100% by mass, it is preferably 0.05% by mass or more, more preferably 0.1% by mass or more, even more preferably 1% by mass or more, preferably 15% by mass or less, more preferably 13% by mass or less, and even more preferably 10% by mass or less.

[0095] The photosensitive resin composition may, in combination with component (C), contain tertiary amines such as ethyl N,N-dimethylaminobenzoate, isoamyl N,N-dimethylaminobenzoate, pentyl-4-dimethylaminobenzoate, triethylamine, and triethanolamine as photopolymerization initiators. One photopolymerization initiator may be used alone, or two or more may be used in combination.

[0096] <(D) Photosensitizers with a molecular weight of 400 or more> The photosensitive resin composition of the present invention contains a photosensitizer with a molecular weight of 400 or more as component (D). The photosensitizer (D) can normally be excited upon receiving light, but the photosensitizer itself does not generate radicals. In addition, when the photosensitizer (D) is excited, it can normally transfer its energy to the photopolymerization initiator (C). The photosensitizer with a molecular weight of 400 or more as component (D) does not include those corresponding to components (A) to (C) described above. Component (D) may be used alone or in combination of two or more types.

[0097] Component (D) has a large molecular weight of 400 or more, so it absorbs more light and gains more energy than photosensitizers with a molecular weight of less than 400. When component (C) receives this energy, the rate of photopolymerization increases. As a result, photopolymerization proceeds before it is inhibited by oxygen, so the photocuring of the photosensitive resin composition can be accelerated, and the solubility in alkaline developer can be rapidly reduced, allowing for a smaller line width (line) and spacing (space) in the core layer, thus enabling the formation of a fine core layer. Furthermore, variations in the degree of insolubilization on the surface of the core layer due to oxygen inhibition can be suppressed, so the surface roughness of the core layer can be reduced, and therefore the surface irregularities of the lines in the core layer can be reduced. In addition, generally, the molecular size of component (D), which has a large molecular weight, is large. The solubility of such large molecules in developer tends to be lower than that of small molecules. Therefore, the frequency of molecular detachment from the core layer surface due to dissolution during development can be suppressed. For example, it is possible to suppress the frequent detachment of small molecules from the core layer surface, which would otherwise lead to the formation of many minute irregularities. Thus, this also reduces the surface irregularities of the core layer lines, improving core formation.

[0098] The molecular weight of component (D) is 400 or more, preferably 450 or more, and more preferably 500 or more, from the viewpoint of being able to form a fine core layer and to manufacture an optical waveguide with minimal surface irregularities in the core and low optical transmission loss. There is no particular upper limit, but it is preferably 3000 or less, more preferably 2500 or less, and even more preferably 2000 or less.

[0099] (D) The maximum absorption wavelength of the photosensitizer is preferably in the range of 300 nm to 450 nm, more preferably in the range of 330 nm to 420 nm, and particularly preferably in the range of 350 nm to 400 nm.

[0100] The lowest excited triplet energy level of component (D) is preferably 60 kcal / mol to 70 kcal / mol, more preferably 60 kcal / mol to 65 kcal / mol, and particularly preferably 60 kcal / mol to 63 kcal / mol.

[0101] (D) Component (D) preferably contains a tertiary amino group in the molecule, and more preferably contains a tertiary amino group at the terminal end of the molecule, from the viewpoint of obtaining the effects of the present invention to be significantly apparent. It is preferable to have one or more tertiary amino groups in the molecule, and more preferably two or more. There is no particular lower limit, but it is preferably 10 or less, and more preferably 5 or less. The tertiary amino group is preferably a tertiary alkylamino group. Examples of tertiary amino groups include dimethylamino group and diethylamino group, with dimethylamino group being preferred.

[0102] (D) Component (D) is preferably a molecule containing an aminobenzoyl group, and more preferably a molecule containing an aminobenzoyl group at the terminal end, from the viewpoint of significantly obtaining the effects of the present invention. It is preferable to have one or more aminobenzoyl groups in the molecule, and more preferably two or more. There is no particular lower limit, but it is preferably 10 or less, and more preferably 5 or less. The aminobenzoyl group is preferably a tertiary alkylaminobenzoyl group, and examples of aminobenzoyl groups include dimethylaminobenzoyl group and diethylaminobenzoyl group, with dimethylaminobenzoyl group being preferred.

[0103] (D) Component preferably includes a compound represented by formula (D-1) from the viewpoint of significantly obtaining the effects of the present invention. [ka] (In the formula, R 41 , R 42 , R 45 , and R 46 Each of these independently represents an alkyl group having 1 to 6 carbon atoms, and R 43 Each of these independently represents a divalent group selected from the group consisting of an alkylene group with 1 to 6 carbon atoms, an oxygen atom, -NR-, and combinations thereof, where R represents a hydrogen atom or an alkyl group with 1 to 3 carbon atoms, 44 (where r represents a divalent group selected from the group consisting of alkylene groups with 1 to 6 carbon atoms, oxygen atoms, and combinations thereof. r represents an integer from 1 to 10.)

[0104] R 41 , R 42 , R 45 , and R 46 Each of these independently represents an alkyl group having 1 to 6 carbon atoms. The alkyl group may be linear, branched, or cyclic, with linear being preferred. Of the alkyl groups having 1 to 6 carbon atoms, alkyl groups having 1 to 5 carbon atoms are preferred, alkyl groups having 1 to 3 carbon atoms are more preferred, and methyl groups are even more preferred.

[0105] R 43Each of these independently represents a divalent group selected from the group consisting of alkylene groups with 1 to 6 carbon atoms, an oxygen atom, -NR-, and combinations thereof, where R represents a hydrogen atom or an alkyl group with 1 to 3 carbon atoms.

[0106] R represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms. Examples of alkyl groups having 1 to 3 carbon atoms include methyl, ethyl, and propyl groups. R is preferably an alkyl group having 1 to 3 carbon atoms, more preferably an alkyl group having 1 or 2 carbon atoms, and even more preferably a methyl group.

[0107] The alkylene group may be linear, branched, or cyclic, with linear being preferred. Of the alkylene groups having 1 to 6 carbon atoms, alkylene groups having 1 to 5 carbon atoms are preferred, alkylene groups having 1 to 3 carbon atoms are more preferred, and alkylene groups having 1 or 2 carbon atoms, or ethylene groups, are even more preferred.

[0108] Divalent groups selected from the group of combinations include, for example, divalent groups consisting of oxyalkylene aminoalkyl structures such as oxymethyleneaminomethyl group, oxyethyleneaminomethyl group, oxypropyleneaminomethyl group, oxybutyleneaminomethyl group, oxypentyleneaminomethyl group, oxyhexyleneaminomethyl group, oxymethyleneaminoethyl group, oxypropyleneaminoethyl group, oxybutyleneaminoethyl group, oxypentyleneaminoethyl group, oxyhexyleneaminoethyl group, etc.; divalent groups consisting of oxyalkylene structures such as oxymethylene group, oxyethylene group, oxypropylene group, oxybutylene group, oxypentylene group, oxyhexylene group, etc.; and methyleneoxy group, ethyleneoxy group, propyleneoxy group, butyleneoxy group, pentyleneoxy group, hexyleneoxy group, etc. Examples include: divalent groups consisting of alkylene oxy structures; divalent groups consisting of oxyalkylene oxy structures such as oxymethylene oxy groups, oxyethylene oxy groups, oxypropylene oxy groups, oxybutylene oxy groups, oxypentylene oxy groups, oxyhexylene oxy groups, etc.; divalent groups consisting of alkylene oxyalkylene structures such as methylene oxymethylene groups, ethylene oxyethylene groups, propylene oxypropylene groups, butylene oxybutylene groups, pentylene oxypentylene groups, hexylene oxyhexylene oxy groups, etc.; and divalent groups consisting of alkylene oxyalkylene oxyalkylene structures such as methylene oxymethylene oxy groups, ethylene oxyethylene oxy groups, propylene oxypropylene oxy groups, butylene oxybutylene oxy groups, pentylene oxypentylene oxy groups, hexylene oxyhexylene oxy groups, etc.

[0109] Among them, R 43 From the viewpoint of significantly obtaining the effects of the present invention, it is preferable that the group is either a divalent group consisting of an oxyalkylene aminoalkyl structure or a divalent group consisting of an oxyalkylene oxy structure. As the divalent group consisting of an oxyalkylene aminoalkyl structure, an oxyethyleneaminomethyl group is preferred. As the divalent group consisting of an oxyalkylene oxy structure, an oxyethylene oxy group is preferred.

[0110] R 44 R represents a divalent group selected from the group consisting of alkylene groups with 1 to 6 carbon atoms, oxygen atoms, and combinations thereof. 43 This is the same as a divalent group selected from the group consisting of alkylene groups with 1 to 6 carbon atoms, or combinations thereof.

[0111] R 44 From the viewpoint of significantly obtaining the effects of the present invention, it is preferable that the group is a divalent group consisting of an alkylene oxy structure. As the divalent group consisting of an alkylene oxy structure, an ethylene oxy group is preferred.

[0112] r represents an integer from 1 to 10, preferably an integer from 1 to 5, more preferably an integer from 1 to 4, and more preferably 3 or 4.

[0113] The nitrogen atom bonded to the benzene ring may be bonded at the ortho, meta, or para position, but from the viewpoint of obtaining the effects of the present invention in particular, it is preferable that it be bonded at the para position.

[0114] R 41 , R 42 , R 45 , and R 46 The alkyl group having 1 to 6 carbon atoms represented by, and R 43 and R 44 The alkylene group having 1 to 6 carbon atoms represented by may have substituents. Examples of substituents include halogen atoms, alkoxy groups, aryl groups, arylalkyl groups, silyl groups, acyl groups, acyloxy groups, carboxyl groups, sulfo groups, cyano groups, nitro groups, hydroxyl groups, mercapto groups, oxo groups, and the like.

[0115] Specific examples of component (D) include the following compounds. However, component (D) is not limited to these specific examples. r1 represents 3 or 4. [ka]

[0116] (D) Component can be a commercially available product. Examples of commercially available products include "Omnipol ASA" and "Esacure A 198" from IGM.

[0117] (D) In ​​terms of the content of component (D), from the viewpoint of significantly obtaining the effects of the present invention, when the nonvolatile component of the photosensitive resin composition is taken as 100% by mass, it is preferably 0.5% by mass or more, more preferably 1% by mass or more, preferably 15% by mass or less, more preferably 13% by mass or less, and even more preferably 10% by mass or less.

[0118] The mass ratio of component (D) to component (A) (mass of component (D) when the non-volatile components of the photosensitive resin composition are set to 100% by mass (mass%) / mass of component (A) when the non-volatile components of the photosensitive resin composition are set to 100% by mass (mass%)) is preferably 1 or more, more preferably 2 or more, and even more preferably 3 or more. The upper limit is preferably 15 or less, more preferably 10 or less, and even more preferably 8 or less.

[0119] The mass ratio of component (D) to component (B) (mass of component (D) when the non-volatile components of the photosensitive resin composition are set to 100% by mass (mass%) / mass of component (B) when the non-volatile components of the photosensitive resin composition are set to 100% by mass (mass%)) is preferably 0.01 or higher, more preferably 0.02 or higher, and even more preferably 0.03 or higher. The upper limit is preferably 1 or lower, more preferably 0.5 or lower, and even more preferably 0.2 or lower.

[0120] The mass ratio of component (D) to component (C) (mass of component (D) when the nonvolatile components of the photosensitive resin composition are set to 100% by mass (mass%) / mass of component (C) when the nonvolatile components of the photosensitive resin composition are set to 100% by mass (mass%)) is preferably 0.1 or higher, more preferably 0.2 or higher, and even more preferably 0.3 or higher. Its upper limit is preferably 35 or lower, more preferably 10 or lower, and even more preferably 5 or lower, and 3 or lower.

[0121] <(E) Inorganic fillers with an average particle size of 100 nm or less> The photosensitive resin composition of the present invention may optionally contain (E) an inorganic filler with an average particle size of 100 nm or less. (E) The inorganic filler is included in the photosensitive resin composition in the form of particles.

[0122] The average particle size of component (E) is 100 nm or less, preferably 90 nm or less, more preferably 80 nm or less, preferably 5 nm or more, and more preferably 10 nm or more, from the viewpoint of suppressing light reflection during exposure and obtaining excellent core formation and developability.

[0123] The average particle size of inorganic fillers can be measured by the laser diffraction-scattering method based on Mie scattering theory. Specifically, a volume-based particle size distribution of the inorganic filler is created using a laser diffraction-scattering particle size distribution analyzer, and the median diameter is used as the average particle size for measurement. A sample of inorganic filler dispersed in water using ultrasound is preferably used for measurement. Suitable laser diffraction-scattering particle size distribution analyzers include the "LA-500" from Horiba, Ltd. and the "SALD-2200" from Shimadzu Corporation.

[0124] (E) The specific surface area of ​​component (E) is preferably 1 m² from the viewpoint of suppressing light reflection during exposure and obtaining excellent core formation properties. 2 / g or more, comfortably 3m 2 / g or more, particularly preferably 5m 2 It must be 1 / g or more. There is no particular upper limit, but preferably 60m 2 / g or less, 50m 2 / g or less or 40m 2 The value is less than / g. The specific surface area is obtained by adsorbing nitrogen gas onto the sample surface using a specific surface area measuring device (Macsorb HM-1210, manufactured by Mountec Co., Ltd.) according to the BET method, and then calculating the specific surface area using the BET multipoint method.

[0125] Inorganic compounds are used as the material for component (E). Examples of materials for component (E) include silica, alumina, glass, cordierite, silicon oxide, barium sulfate, barium carbonate, talc, clay, mica powder, zinc oxide, hydrotalcite, boehmite, aluminum hydroxide, magnesium hydroxide, calcium carbonate, magnesium carbonate, magnesium oxide, boron nitride, aluminum nitride, manganese nitride, aluminum borate, strontium carbonate, strontium titanate, calcium titanate, magnesium titanate, bismuth titanate, titanium oxide, zirconium oxide, barium titanate, barium zirconate titanate, barium zirconate, calcium zirconate, zirconium phosphate, and zirconium tungstate phosphate. Among these, silica is particularly preferred. Examples of silica include amorphous silica, fused silica, crystalline silica, synthetic silica, and hollow silica. Spherical silica is preferred as silica. Component (E) may be used alone or in combination of two or more in any ratio.

[0126] (E) Component can be a commercially available product. Examples of such commercially available products include Admatex's "Admanano series" such as Y50SZ-AM1, Denki Kagaku Kogyo's "UFP series", Sakai Kagaku Kogyo's "Sciqas series", Nippon Shokubai's "Seahostar series", and Sakai Kagaku Kogyo's "BF series".

[0127] Component (E) is preferably treated with a surface treatment agent from the viewpoint of improving moisture resistance and dispersibility. Examples of surface treatment agents include fluorine-containing silane coupling agents, aminosilane coupling agents, epoxysilane coupling agents, mercaptosilane coupling agents, silane coupling agents, alkoxysilanes, organosilazane compounds, titanate coupling agents, etc. Furthermore, the surface treatment agent may be used alone or in any combination of two or more types.

[0128] Examples of commercially available surface treatment agents include "KBM403" (3-glycidoxypropyltrimethoxysilane), "KBM803" (3-mercaptopropyltrimethoxysilane), "KBE903" (3-aminopropyltriethoxysilane), "KBM573" (N-phenyl-3-aminopropyltrimethoxysilane), "SZ-31" (hexamethyldisilazane), "KBM103" (phenyltrimethoxysilane), "KBM-4803" (long-chain epoxy-type silane coupling agent), and "KBM-7103" (3,3,3-trifluoropropyltrimethoxysilane), all manufactured by Shin-Etsu Chemical Co., Ltd.

[0129] From the viewpoint of improving the dispersibility of the inorganic filler, the degree of surface treatment by the surface treatment agent is preferably within a predetermined range. Specifically, 100% by mass of the inorganic filler is preferably surface-treated with 0.2% to 5% by mass of the surface treatment agent, more preferably with 0.2% to 3% by mass, and even more preferably with 0.3% to 2% by mass.

[0130] The degree of surface treatment by a surface treatment agent can be evaluated by the amount of carbon per unit surface area of ​​the inorganic filler. From the viewpoint of improving the dispersibility of the inorganic filler, the amount of carbon per unit surface area of ​​the inorganic filler should be 0.02 mg / m². 2 The above is preferred, and 0.1 mg / m² 2 The above is more preferable, 0.2 mg / m²2 The above is even more preferable. On the other hand, from the viewpoint of preventing an increase in the melt viscosity of the resin composition and the melt viscosity in sheet form, 1.0 mg / m² 2 The following is preferred: 0.8 mg / m² 2 The following is more preferable: 0.5 mg / m² 2 The following are even more preferable.

[0131] The amount of carbon per unit surface area of ​​component (E) can be measured after cleaning the inorganic filler with a solvent (e.g., methyl ethyl ketone (MEK)) following surface treatment. Specifically, a sufficient amount of MEK is added to the inorganic filler that has been surface-treated with a surface treatment agent, and ultrasonic cleaning is performed at 25°C for 5 minutes. After removing the supernatant and drying the solids, the amount of carbon per unit surface area of ​​the inorganic filler can be measured using a carbon analyzer. A carbon analyzer such as the "EMIA-320V" manufactured by Horiba, Ltd. can be used.

[0132] The content of component (E), when the nonvolatile components in the photosensitive resin composition are considered to be 100% by mass, is preferably 5% by mass or more, more preferably 10% by mass or more, even more preferably 15% by mass or more, preferably 35% by mass or less, more preferably 30% by mass or less, and even more preferably 25% by mass or less, from the viewpoint of significantly obtaining the effects of the present invention.

[0133] <(F) Reactive Diluent> The photosensitive resin composition of the present invention may contain a reactive diluent (F) as an optional component. This reactive diluent (F) does not include any of the components (A) to (E) described above. Component (F) may be used alone or in combination of two or more types.

[0134] (F) Photoreactivity can be improved by including a reactive diluent in the photosensitive resin composition. (F) As the reactive diluent, for example, a (meth)acrylate compound having one or more (preferably two or more) (meth)acryloyl groups in one molecule can be used.

[0135] Representative (meth)acrylate compounds include, for example, hydroxyalkyl acrylates such as 2-hydroxyethyl acrylate and 2-hydroxybutyl acrylate; mono- or diacrylates of glycols such as ethylene glycol, methoxytetraethylene glycol, polyethylene glycol, and propylene glycol; acrylamides such as N,N-dimethylacrylamide and N-methylolacrylamide; aminoalkyl acrylates such as N,N-dimethylaminoethyl acrylate; polyhydric acrylates of polyhydric alcohols such as trimethylolpropane, pentaerythritol, and dipentaerythritol, or adducts thereof to ethylene oxide, propylene oxide, or ε-caprolactone; acrylates of phenols such as phenoxyacrylate and phenoxyethyl acrylate, or their ethylene oxide or propylene oxide adducts; epoxy acrylates derived from glycidyl ethers such as trimethylolpropane triglycidyl ether; modified epoxy acrylates; melamine acrylates; and / or methacrylates corresponding to the above acrylates.Among these, polyvalent acrylates or polyvalent methacrylates are preferred. For example, trivalent acrylates or methacrylates include trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, trimethylolpropane EO-added tri(meth)acrylate, glycerin PO-added tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, tetrafurfuryl alcohol oligo(meth)acrylate, ethyl carbitol oligo(meth)acrylate, 1,4-butanediol oligo(meth)acrylate, 1,6-hexanediol oligo(meth)acrylate, trimethylolpropane oligo(meth)acrylate, pentaerythritol oligo(meth)acrylate, tetramethylolmethane tetra(meth)acrylate, and dipentaerythritol Examples include trivalent (meth)acrylates such as hexa(meth)acrylate and N,N,N',N'-tetrakis(β-hydroxyethyl)ethyldiamine (meth)acrylic acid esters. Examples of trivalent or higher acrylates or methacrylates include phosphate triester (meth)acrylates such as tri(2-(meth)acryloyloxyethyl) phosphate, tri(2-(meth)acryloyloxypropyl) phosphate, tri(3-(meth)acryloyloxypropyl) phosphate, tri(3-(meth)acryloyl-2-hydroxyloxypropyl) phosphate, di(3-(meth)acryloyl-2-hydroxyloxypropyl)(2-(meth)acryloyloxyethyl) phosphate, and (3-(meth)acryloyl-2-hydroxyloxypropyl)di(2-(meth)acryloyloxyethyl) phosphate. These photosensitive (meth)acrylate compounds may be used individually or in combination of two or more. "EO" refers to ethylene oxide.

[0136] (F) A commercially available reaction diluent may be used. Examples of commercially available products include "DPHA" manufactured by Nippon Kayaku Co., Ltd. and "EBECRYL3708" manufactured by Daicel Ornex Co., Ltd.

[0137] (F) Reactive diluents typically have low viscosity. (F) The specific viscosity of reactive diluents is usually less than 0.5 Pa·s. (F) There is no particular lower limit to the viscosity of reactive diluents; for example, it may be 0.001 Pa·s or higher, 0.005 Pa·s or higher, 0.01 Pa·s or higher, etc. (F) The viscosity of reactive diluents can be measured using an E-type viscometer at 25 ± 2°C.

[0138] (F) The content of the reaction diluent is preferably 5% by mass or more, more preferably 10% by mass or more, preferably 40% by mass or less, more preferably 35% by mass or less, and even more preferably 30% by mass or less, when the nonvolatile components in the photosensitive resin composition are considered to be 100% by mass, from the viewpoint of promoting photocuring.

[0139] <(G) Solvent> The photosensitive resin composition may contain a solvent (G) as a volatile component in combination with the non-volatile components such as components (A) to (F) described above. The viscosity of the photosensitive resin composition can be adjusted depending on the solvent (G) used as component (G). Examples of solvents (G) include organic solvents.

[0140] (G) Examples of solvents include ketone solvents such as ethyl methyl ketone (MEK) and cyclohexanone; aromatic hydrocarbon solvents such as toluene, xylene, and tetramethylbenzene; glycol ether solvents such as methyl cellosolve, butyl cellosolve, methyl carbitol, butyl carbitol, propylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol diethyl ether, and triethylene glycol monoethyl ether; ester solvents such as ethyl acetate, butyl acetate, butyl cellosolve acetate, carbitol acetate, and ethyl diglycol acetate; ether ester solvents such as propylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, ethyl diglycol acetate, γ-butyrolactone, and methyl methoxypropionate; aliphatic hydrocarbon solvents such as octane and decane; and petroleum-based solvents such as petroleum ether, petroleum naphtha, hydrogenated petroleum naphtha, and solvent naphtha. (G) Solvents may be used individually or in combination of two or more types.

[0141] (G) The amount of solvent is preferably adjusted appropriately from the viewpoint of the applicability of the photosensitive resin composition.

[0142] <(H) Any additives> The photosensitive resin composition of the present invention may further contain (H) any additive as an optional component, in combination with the components (A) to (G) described above, to the extent that it does not significantly impair the effects of the present invention. This optional additive (H) does not include any components (A) to (G) described above. The optional additive (H) may be used alone or in combination of two or more types.

[0143] (H) Examples of optional additives include photosensitizers, UV absorbers, silane coupling agents, plasticizers, flame retardants, antistatic agents, anti-aging agents, antibacterial agents, defoaming agents, leveling agents, thickeners, adhesion promoters, thixotropic agents, mold release agents, surface treatment agents, dispersants, surface modifiers, stabilizers, etc., with a molecular weight of less than 400.

[0144] A photosensitive resin composition can be manufactured as a resin varnish by mixing the above components (A) to (D) as essential components, appropriately mixing the above components (E) to (H) as optional components, and kneading or stirring the mixture using a kneading means such as a three-roll mill, ball mill, bead mill, or sand mill, or a stirring means such as a super mixer, planetary mixer, or high-speed rotary mixer, as needed.

[0145] <Physical properties and applications of photosensitive resin compositions> The photosensitive resin composition described above can be used to form the core layer of an optical waveguide. The formed core layer usually contains a cured product of the photosensitive resin composition described above. The photosensitive resin composition can usually be cured by light, and preferably by light and heat. Generally, among the components contained in the photosensitive resin composition, (G) solvent is a volatile component and may volatilize due to the heat during curing, but other non-volatile components do not volatilize due to the heat during curing. Therefore, the cured product of the photosensitive resin composition may contain the non-volatile components of the photosensitive resin composition or their reaction products. Preferably, the core layer contains only the cured product of the photosensitive resin composition.

[0146] The photosensitive resin composition exhibits excellent core-forming properties because it contains a combination of components (A) to (D). Specifically, when the photosensitive resin composition is exposed and developed to form line layers corresponding to the core layer, it is possible to form line layers with a small minimum fine formation width. For example, when the photosensitive resin composition is exposed and developed to form line layers with L / S (line / space) of 10 μm / 10 μm, 5 μm / 5 μm, and 3 μm / 3 μm, the aspect ratio of the line layer can be preferably 0.6 or higher, more preferably 0.8 or higher, and even more preferably 1 or higher. Here, in L / S, L (line) represents the width of the line layer, and S (space) represents the spacing between lines. The aspect ratio of the line layer represents the ratio expressed as "layer thickness / line width" of the line layer. With a photosensitive resin composition having such excellent core-forming properties, it is possible to form core layers with small widths and spacings, thereby achieving miniaturization of optical waveguides. The minimum fine formation width can be measured according to the method described in the examples below.

[0147] The photosensitive resin composition contains a combination of components (A) to (D), and therefore exhibits excellent core-forming properties. Specifically, it can suppress the formation of surface irregularities on the line layer corresponding to the core layer. For example, when a line layer is formed by exposure and development of the photosensitive resin composition, the formation of surface irregularities on the line layer is suppressed. For example, when line layers with L / S (line / space) of 10 μm / 10 μm, 5 μm / 5 μm, and 3 μm / 3 μm are formed by exposure and development of the photosensitive resin composition. In this case, there are no irregularities on the surface of any of the line layers. With a photosensitive resin composition in which the occurrence of surface irregularities is suppressed in this way, a core layer without surface irregularities can be formed, and optical transmission loss can be reduced. Surface irregularities can be evaluated according to the method described in the examples below.

[0148] The photosensitive resin composition exhibits the characteristic of reducing optical transmission loss because it contains a combination of components (A) to (D). Specifically, a test substrate is prepared having a cladding layer and a core layer formed using the photosensitive resin composition. The optical transmission loss is measured using this test substrate. At this time, the optical transmission loss is preferably less than 2 dB / cm, more preferably less than 1 dB / cm. The lower limit is not particularly limited, but it can be 0 dB / cm or more, 0.1 dB / cm or more, etc. The optical transmission loss can be measured according to the method described in the examples below.

[0149] The photosensitive resin composition contains a combination of components (A) to (D), and therefore typically exhibits the characteristic of yielding a cured product with excellent absorbance at 1310 nm. Specifically, the photosensitive resin composition is dissolved in a solvent to prepare a photosensitive resin composition solution. The absorbance of this photosensitive resin composition solution at 1310 nm is measured using an ultraviolet-visible-near-infrared spectrophotometer. At this time, the absorbance is preferably less than 0.0100, more preferably less than 0.0050, and even more preferably less than 0.0025. The lower limit is not particularly limited, but it may be 0.0001 or higher. The absorbance can be measured according to the method described in the examples below.

[0150] The photosensitive resin composition of the present invention can typically have its unexposed areas, which have not been irradiated with light, removed by a developer. In particular, the photosensitive resin composition of the present invention can be effectively removed by a sodium carbonate solution as an alkaline developer. Therefore, the photosensitive resin composition of the present invention can be suitably used for sodium carbonate development.

[0151] Furthermore, the photosensitive resin composition of the present invention exhibits excellent core-forming properties and can reduce optical transmission loss, making it suitable for use as a photosensitive resin composition for forming the core layer of an optical waveguide. Therefore, the photosensitive resin composition of the present invention can be suitably used for manufacturing the core layer of an optical waveguide (photosensitive resin composition for forming the core layer of an optical waveguide) and for forming an optical waveguide capable of transmitting light with wavelengths of 1300 nm to 1320 nm (photosensitive resin composition for the application of forming an optical waveguide capable of transmitting light with wavelengths of 1300 nm to 1320 nm). The photosensitive resin composition of the present invention is preferably used for forming a single-mode optical waveguide, for example, for light with a wavelength of 1310 nm.

[0152] [Resin sheet] The photosensitive resin composition of the present invention can be suitably used in the form of a resin sheet in which a photosensitive resin composition layer is formed on a support. That is, the resin sheet includes a support and a photosensitive resin composition layer formed on the support, which is made of the photosensitive resin composition of the present invention.

[0153] Examples of support materials include polyethylene terephthalate film, polyethylene naphthalate film, polypropylene film, polyethylene film, polyvinyl alcohol film, and triacetyl acetate film, with polyethylene terephthalate film being particularly preferred.

[0154] Examples of commercially available supports include, but are not limited to, polypropylene films such as "Alfan MA-410" and "E-200C" from Oji Paper Co., Ltd., and polyethylene terephthalate films such as the PS series "PS-25" from Teijin Corporation. These supports are preferably coated with a release agent such as a silicone coating agent on their surface to facilitate the removal of the photosensitive resin composition layer. The thickness of the support is preferably in the range of 5 μm to 50 μm, and more preferably in the range of 10 μm to 25 μm. A thickness of 5 μm or more can suppress tearing of the support when peeling it off before development, and a thickness of 50 μm or less can improve the resolution when exposing the support. Furthermore, a low-fisheye support is preferred. Here, "fisheye" refers to the incorporation of foreign matter, undissolved material, oxidized degradation products, etc., into the film when the material is heat-melted, kneaded, extruded, biaxially stretched, cast, etc.

[0155] Furthermore, in order to reduce light scattering during exposure by active light such as ultraviolet rays, the support material is preferably one with excellent transparency. Specifically, the support material is preferably one with a turbidity (haze, as standardized in JIS-K6714), which is an indicator of transparency, of 0.1 to 5. In addition, the photosensitive resin composition layer may be protected by a protective film.

[0156] By protecting the photosensitive resin composition layer of the resin sheet with a protective film, it is possible to prevent dust and other debris from adhering to the surface of the photosensitive resin composition layer and to prevent scratches. The protective film can be made of the same material as the support described above. The thickness of the protective film is not particularly limited, but it is preferably in the range of 1 μm to 40 μm, more preferably in the range of 5 μm to 30 μm, and even more preferably in the range of 10 μm to 30 μm. A thickness of 1 μm or more improves the handling of the protective film, while a thickness of 40 μm or less tends to improve cost-effectiveness. It is preferable that the adhesive strength between the photosensitive resin composition layer and the protective film is less than the adhesive strength between the photosensitive resin composition layer and the support.

[0157] A resin sheet can be manufactured, for example, by preparing a resin varnish by dissolving the photosensitive resin composition of the present invention in an organic solvent, applying this resin varnish to a support, and drying the organic solvent by heating or hot air blowing to form a photosensitive resin composition layer. Specifically, a resin sheet can be manufactured by first completely removing bubbles from the photosensitive resin composition by a vacuum degassing method or the like, then applying the photosensitive resin composition to a support, removing the solvent using a hot air furnace or far-infrared furnace and drying it, and then laminating a protective film on the obtained photosensitive resin composition layer as needed. The specific drying conditions vary depending on the curability of the photosensitive resin composition and the amount of organic solvent in the resin varnish, but for a resin varnish containing 30% to 60% by mass of organic solvent, it can be dried at 80°C to 120°C for 3 to 13 minutes. The amount of residual organic solvent in the photosensitive resin composition layer is preferably 5% by mass or less, and more preferably 2% by mass or less, relative to the total amount of the photosensitive resin composition layer, in order to prevent the diffusion of the organic solvent in subsequent processes. Those skilled in the art can determine suitable drying conditions through simple experiments.

[0158] The thickness of the photosensitive resin composition layer is preferably 1 μm or more, more preferably 2 μm or more, even more preferably 3 μm or more, preferably 15 μm or less, more preferably 13 μm or less, and even more preferably 10 μm or less, from the viewpoint of improving handling and suppressing a decrease in sensitivity and resolution inside the photosensitive resin composition layer.

[0159] Examples of coating methods for photosensitive resin compositions include gravure coating, microgravure coating, reverse coating, kiss reverse coating, die coating, slot die coating, lip coating, comma coating, blade coating, roll coating, knife coating, curtain coating, chamber gravure coating, slot orifice coating, spray coating, and dip coating.

[0160] The photosensitive resin composition may be applied in several stages, in a single stage, or by combining multiple different methods. Among these, the die-coating method is preferred because it offers excellent uniformity. Furthermore, to avoid contamination with foreign matter, it is preferable to carry out the coating process in an environment with minimal foreign matter generation, such as a cleanroom.

[0161] [Photosensitive resin composition set] The photosensitive resin composition of the present invention can be suitably used as a photosensitive resin composition for forming the core layer of an optical waveguide. Therefore, the photosensitive resin composition set includes the photosensitive resin composition of the present invention and a photosensitive resin composition for cladding. The photosensitive resin composition set can be used for manufacturing an optical waveguide comprising a core layer containing a cured product of the photosensitive resin composition of the present invention and a cladding layer containing a cured product of the photosensitive resin composition for cladding. A known photosensitive resin composition can be used as the photosensitive resin composition for cladding. Since both the photosensitive resin composition of the present invention and the photosensitive resin composition for cladding are photosensitive resin compositions, it is usually possible to efficiently manufacture fine optical waveguides by a method including exposure and development.

[0162] [Optical waveguide] The photosensitive resin composition, resin sheet, and photosensitive resin composition set described above can be used in the manufacture of optical waveguides. Hereinafter, embodiments of such optical waveguides will be described with reference to the drawings.

[0163] Figure 1 is a schematic perspective view showing an optical waveguide 10 according to one embodiment of the present invention. As shown in Figure 1, the optical waveguide 10 comprises a core layer 100 and a cladding layer 200. The core layer 100 contains a cured product of the photosensitive resin composition of the present invention, preferably containing only the cured product of the photosensitive resin composition of the present invention. The cladding layer 200 contains a cured product of a cladding resin composition, preferably containing only the cured product of the cladding resin composition. As the cladding resin composition, a resin composition that yields a cured product having a lower refractive index than the cured product of the photosensitive resin composition of the present invention can be used. As the cladding resin composition, a photocurable resin composition or a thermosetting resin composition may be used.

[0164] The core layer 100 is provided within the cladding layer 200. Therefore, the core layer 100 is covered by the cladding layer 200. Typically, the entire circumferential surface of the core layer 100 is covered by the cladding layer 200. The core layer 100 and the cladding layer 200 are in direct contact without any other layers in between, and therefore, an interface 100I can be formed between the core layer 100 and the cladding layer 200. Typically, the core layer 100 has a higher refractive index than the cladding layer 200, and therefore, light (not shown) can be transmitted through the core layer 100 from one end (incident end) 100A to the other end (exit end) 100B.

[0165] The wavelengths of light that the optical waveguide 10 can transmit can be selected from a variety of options. For example, preferred wavelength ranges for the transmitted light may be 840nm to 860nm (e.g., 850nm), 1300nm to 1320nm (e.g., 1310nm), 1540nm to 1560nm (e.g., 1550nm), etc. Among these, the preferred wavelength range for the light transmitted through the optical transmission path 10 is 1300nm to 1320nm.

[0166] The optical waveguide 10 may be a single-mode optical waveguide or a multi-mode optical waveguide, but it is preferable that it be a single-mode optical waveguide. In particular, it is preferable that the optical waveguide 10 is a single-mode optical waveguide for light in the preferred wavelength range mentioned above. For example, it is preferable that the optical waveguide 10 is a single-mode optical waveguide for light at 1310 nm.

[0167] The width L of the core layer 100 is preferably set appropriately within a range that allows light transmission. The specific range of the line width L of the core layer 100 is preferably 0.5 μm or more, more preferably 1 μm or more, particularly preferably 2 μm or more, preferably 50 μm or less, more preferably 30 μm or less, particularly preferably 20 μm or less, and may also be 10 μm or less or 5 μm or less. The width L of the core layer 100 corresponds to the line width (line) of the core layer 100 when viewed from the thickness direction.

[0168] The spacing S of the core layers 100 should preferably be set appropriately within a range that allows light transmission. Specifically, the range of the spacing S of the core layers 100 is preferably 50 μm or more, more preferably 70 μm or more, particularly preferably 100 μm or more, preferably 1000 μm or less, more preferably 500 μm or less, and particularly preferably 300 μm or less. The spacing S of the core layers 100 corresponds to the spacing (space) of the core layers as viewed from the thickness direction.

[0169] The thickness T of the core layer 100 is preferably set appropriately within a range that allows light transmission. The specific range of the thickness T of the core layer 100 is preferably 0.5 μm or more, more preferably 1 μm or more, particularly preferably 2 μm or more, preferably 50 μm or less, more preferably 30 μm or less, particularly preferably 20 μm or less, and may also be 10 μm or less.

[0170] The thickness of the cladding layer 200 is usually greater than the thickness of the core layer 100. The specific thickness of the cladding layer 200 is preferably 5 μm or more, more preferably 7 μm or more, particularly preferably 10 μm or more, preferably 40 μm or less, more preferably 30 μm or less, and particularly preferably 20 μm or less.

[0171] The optical waveguide 10 may include any elements other than the core layer 100 and the cladding layer 200, as needed. For example, the optical waveguide 10 may include a substrate 300. In an optical waveguide 10 that includes a substrate 300, the cladding layer 200 is usually provided on the substrate 300, and the core layer 100 is provided within the cladding layer 200.

[0172] As the substrate 300, a hard substrate such as a glass substrate, metal substrate, ceramic substrate, wafer, or circuit board may be used. As the wafer, for example, a semiconductor wafer such as a silicon wafer, gallium arsenide (GaAs) wafer, indium phosphide (InP) wafer, gallium phosphide (GaP) wafer, gallium nitride (GaN) wafer, gallium tellurium (GaTe) wafer, zinc selenium (ZnSe) wafer, or silicon carbide (SiC) wafer may be used, or a pseudo-wafer may be used. As a pseudo-wafer, for example, a plate-shaped member comprising a mold resin and electronic components embedded in the mold resin may be used. As the circuit board, for example, a glass epoxy substrate, metal substrate, polyester substrate, polyimide substrate, BT resin substrate, thermosetting polyphenylene ether substrate, etc. Here, a circuit board refers to a substrate on which a conductive layer (circuit) with a pattern is formed on one or both sides of the above substrate. Furthermore, as the substrate 300, a film made of a plastic material such as polyethylene terephthalate, polyimide, or polyester may be used. Furthermore, a flexible circuit board may be used as the board 300.

[0173] Furthermore, the optical waveguide 10 may optionally include a protective layer (not shown) that protects the core layer 100 and the cladding layer 200. The protective layer may, for example, be provided to cover the side of the cladding layer 200 opposite to the substrate 300.

[0174] As described above, the optical waveguide 10 can have low transmission loss. Furthermore, since the core layer 100 of the optical waveguide 10 has excellent core-forming properties, the occurrence of surface irregularities can be suppressed and the core layer can be made finely wired, making it possible to form it with a small line width L as described above.

[0175] The optical waveguide 10 can be manufactured using the photosensitive resin composition of the present invention. For example, the optical waveguide 10 is Step (I) of forming a first composition layer containing a cladding resin composition, The first composition layer is cured (II), Step (III) is to form a second composition layer containing the photosensitive resin composition of the present invention on a first composition layer, Step (IV) of applying an exposure treatment to the second composition layer, Step (V) involves developing the second composition layer, The process of curing the second composition layer (VI), Step (VII) of forming a third composition layer containing a cladding resin composition on a second composition layer, The third composition layer is cured (VIII), It can be manufactured by a method that includes these elements in this order.

[0176] Figure 2 is a schematic cross-sectional view illustrating step (I) of a method for manufacturing an optical waveguide according to one embodiment of the present invention. As shown in Figure 2, the method for manufacturing an optical waveguide according to one embodiment of the present invention includes step (I) of forming a first composition layer 210 containing a photosensitive resin composition for cladding. In this embodiment, an example of forming the first composition layer 210 on a substrate 300 will be shown and explained.

[0177] There are no particular restrictions on the method for forming the first composition layer 210. For example, the first composition layer 210 may be formed by applying the cladding resin composition onto the substrate 300. From the viewpoint of smooth application, a varnish-like cladding resin composition containing a solvent may be prepared and this varnish-like cladding resin composition may be applied.

[0178] Examples of coating methods include gravure coating, microgravure coating, reverse coating, kiss reverse coating, die coating, slot die coating, lip coating, comma coating, blade coating, roll coating, knife coating, curtain coating, chamber gravure coating, slot orifice coating, spin coating, slit coating, spray coating, dip coating, hot melt coating, bar coating, applicator coating, air knife coating, curtain flow coating, offset printing, brush coating, and screen printing.

[0179] The cladding resin composition may be applied in a single application or in multiple applications. Alternatively, different application methods may be combined. To avoid contamination, application is preferably carried out in an environment with minimal foreign matter generation, such as a cleanroom.

[0180] After applying the cladding resin composition, the first composition layer 210 may be dried as needed. Drying can be performed using a drying apparatus such as a hot air furnace or a far-infrared furnace. The drying conditions are preferably set appropriately according to the composition of the cladding resin composition. Specifically, the drying temperature is preferably 50°C or higher, more preferably 70°C or higher, particularly preferably 80°C or higher, preferably 150°C or lower, more preferably 130°C or lower, and particularly preferably 120°C or lower. The drying time is preferably 30 seconds or more, more preferably 60 seconds or more, particularly preferably 120 seconds or more, preferably 60 minutes or less, more preferably 20 minutes or less, and particularly preferably 5 minutes or less.

[0181] The first composition layer 210 may be formed, for example, using a cladding resin sheet that includes a cladding photosensitive resin composition layer comprising a support and a cladding photosensitive resin composition. Specifically, the first composition layer 210 can be formed on the substrate 300 by laminating the cladding photosensitive resin composition layer of the cladding resin sheet to the substrate 300. Lamination is usually performed by pressing the cladding photosensitive resin composition layer of the resin sheet onto the substrate 300 while heating it. This lamination is preferably performed under reduced pressure by a vacuum lamination method. Alternatively, a preheating treatment may be performed on the resin sheet and substrate before lamination, if necessary.

[0182] Lamination conditions include, for example, a bonding temperature of 70°C to 140°C and a bonding pressure of 1 kgf / cm². 2 ~11 kgf / cm² 2 (9.8 × 10 4 N / m 2 ~107.9×10 4 N / m 2 The lamination can be carried out under conditions of a crimping time of 5 to 300 seconds. Furthermore, it is preferable to perform the lamination under reduced pressure with an air pressure of 20 mmHg (26.7 hPa) or less. Lamination may be carried out in a batch manner or in a continuous manner using a roll.

[0183] Vacuum lamination can be performed using a commercially available vacuum laminator. Examples of commercially available vacuum laminators include the vacuum applicator manufactured by Nikko Materials, the vacuum pressure laminator manufactured by Meiki Seisakusho, the roll-type dry coater manufactured by Hitachi Industries, and the vacuum laminator manufactured by Hitachi AIC.

[0184] When the first composition layer 210 is formed using a cladding resin sheet with a support, the support is usually peeled off at an appropriate time prior to step (III).

[0185] The first composition layer 210 formed on the substrate 300 in step (I) usually contains a cladding resin composition, and preferably contains only a cladding resin composition.

[0186] A method for manufacturing an optical waveguide according to one embodiment of the present invention includes a step (II) for curing the first composition layer 210 after step (I). Step (II) may be, for example, heat treatment of the first composition layer 210. The heat treatment conditions may be selected according to the type and amount of resin component in the cladding resin composition, preferably in the range of 150°C to 250°C for 20 minutes to 180 minutes, and more preferably in the range of 160°C to 230°C for 30 minutes to 120 minutes. The heat treatment is preferably carried out in an inert atmosphere such as a nitrogen atmosphere.

[0187] Furthermore, the curing of the first composition layer 210 may be carried out by exposure treatment. In one example, the specific exposure amount range is preferably 10 mJ / cm². 2 More specifically, 50 mJ / cm² 2 The above is particularly preferably 200 mJ / cm². 2 The above is preferable, preferably 10,000 mJ / cm². 2 More preferably, 8,000 mJ / cm² 2 More preferably, 4,000 mJ / cm² 2 The following is particularly preferred: 1,000 mJ / cm² 2 The following applies. Furthermore, the first composition layer 210 may be cured by combining exposure treatment and heat treatment.

[0188] Figure 3 is a schematic cross-sectional view illustrating step (II) of a method for manufacturing an optical waveguide according to one embodiment of the present invention. By curing the first composition layer 210 in step (II), a cured first composition layer 220 is obtained on the substrate 300, as shown in Figure 3. This cured first composition layer 220 forms a part of the cladding layer 200 and may hereinafter be referred to as the "lower cladding layer" 220.

[0189] Figure 4 is a schematic cross-sectional view illustrating step (III) of a method for manufacturing an optical waveguide according to one embodiment of the present invention. The method for manufacturing an optical waveguide according to one embodiment of the present invention includes, after step (II), step (III) of forming a second composition layer 110 containing the photosensitive resin composition of the present invention on a lower cladding layer 220 as a cured first composition layer, as shown in Figure 4.

[0190] There are no particular restrictions on the method for forming the second composition layer 110. For example, the second composition layer 110 may be formed by applying the photosensitive resin composition of the present invention onto the lower cladding layer 220. From the viewpoint of smooth application, a varnish-like photosensitive resin composition containing a solvent may be prepared and this varnish-like photosensitive resin composition may be applied. The application of the photosensitive resin composition of the present invention can be carried out in the same manner as the application of the cladding resin composition. Furthermore, after the application of the photosensitive resin composition of the present invention, the second composition layer 110 may be dried as needed. The drying of the second composition layer 110 can be carried out using the same method and conditions as the drying of the first composition layer 210.

[0191] The second composition layer 110 may be formed, for example, using a resin sheet. Specifically, the second composition layer 110 can be formed on the lower cladding layer 220 by laminating the photosensitive resin composition layer of the resin sheet onto the lower cladding layer 220. The lamination of the resin sheet can be carried out in the same way as the lamination of the cladding resin sheet. The support of the resin sheet is peeled off at an appropriate time before step (V).

[0192] In step (III), the second composition layer 110 formed on the lower cladding layer 220 typically contains the photosensitive resin composition of the present invention, and preferably contains only the photosensitive resin composition of the present invention.

[0193] Figure 5 is a schematic cross-sectional view illustrating step (IV) of a method for manufacturing an optical waveguide according to one embodiment of the present invention. As shown in Figure 5, the method for manufacturing an optical waveguide according to one embodiment of the present invention includes step (IV), in which the second composition layer 110 is subjected to an exposure treatment after step (III).

[0194] In step (V), a latent image is formed in the second composition layer 110 by exposure treatment. Specifically, in the exposure treatment, light P is selectively irradiated onto a specific portion of the second composition layer 110. Therefore, after exposure treatment, the second composition layer 110 is provided with an exposed portion 111 that has been irradiated with light and an unexposed portion 112 that has not been irradiated with light. Typically, the core resin composition functions as a negative-type photosensitive resin composition, so a latent image corresponding to the core layer is formed by the exposed portion 111.

[0195] From the viewpoint of selective exposure, the exposure process in step (V) is usually performed using a mask 400. Specifically, in this exposure process, light P is irradiated onto the second composition layer 110 through a mask 400 having a light-transmitting portion 410 and a light-shielding portion 420. The light P passes through the light-transmitting portion 410 and enters the exposure portion 111, but cannot pass through the light-shielding portion 420 and therefore cannot enter the non-exposure portion 112. Thus, the exposure portion 111 and the non-exposure portion 112 corresponding to the light-transmitting portion 410 and the light-shielding portion 420 can be provided in the second composition layer 110. The mask 400 may be in close contact with the second composition layer 110 as shown in Figure 5 (contact exposure method), or exposure may be performed using parallel light rays without contact (non-contact exposure method).

[0196] Generally, the light-transmitting portion 410 of the mask 400 is formed to have a planar shape corresponding to the core layer of the optical waveguide. Therefore, the light-shielding portion 420 of the mask 400 is formed to have a planar shape corresponding to the portion of the optical waveguide that does not have a core layer. Unless otherwise specified, "planar shape" refers to the shape as viewed from the thickness direction. The light-transmitting portion 410 formed to have a planar shape corresponding to the core layer may hereafter be referred to as the "mask pattern".

[0197] In the exposure treatment in step (V), it is preferable to use an appropriate active light P depending on the composition of the photosensitive resin composition of the present invention. The wavelength of the active light is usually 190 nm to 1000 nm, preferably 240 nm to 550 nm, but other wavelengths of light may also be used. Specific examples of active light sources include ultraviolet light, visible light, electron beams, X-rays, etc., with ultraviolet light being particularly preferred. The exposure amount of light P is preferably set so that a desired core layer can be formed after curing in step (VII). In one example, the specific exposure amount range in step (V) is preferably 10 mJ / cm². 2 More specifically, 50 mJ / cm² 2 The above is particularly preferably 200 mJ / cm². 2 The above is preferable, preferably 10,000 mJ / cm². 2 More preferably, 8,000 mJ / cm² 2 More preferably, 4,000 mJ / cm² 2 The following is particularly preferred: 1,000 mJ / cm² 2 The following applies:

[0198] When the second composition layer 110 is formed using the resin sheet of the present invention, a support (not shown) may be present on the second composition layer 110 in step (IV). If a support is present on the second composition layer 110, exposure may be performed through the support, or exposure may be performed after the support has been removed.

[0199] Since the photosensitive resin composition of the present invention functions as a negative-type photosensitive resin composition, its solubility in the developer decreases in the exposed area 111. On the other hand, its solubility in the developer is high in the unexposed area 112. This difference in solubility between the exposed area 111 and the unexposed area 112 is utilized to perform the development process in the subsequent step (VI).

[0200] A method for manufacturing an optical waveguide according to one embodiment of the present invention may include a step (IX) after step (IV) and before step (V), in which the second composition layer 110 is heated, from the viewpoint of curing the second composition layer 110. Step (IX) can quickly reduce the solubility of the exposed portion 111 in the developer. The heating in step (IX) may be performed using a hot plate or an oven. The heating temperature may be, for example, 40°C to 110°C. The heating time may be, for example, 30 seconds to 60 minutes.

[0201] Figure 6 is a schematic cross-sectional view illustrating step (V) of a method for manufacturing an optical waveguide according to one embodiment of the present invention. The method for manufacturing an optical waveguide according to one embodiment of the present invention includes step (V) of applying a developing treatment to the second composition layer 110 after step (IV). The developing treatment allows the latent image formed in step (IV) to be developed. Since the photosensitive resin composition of the present invention functions as a negative-type photosensitive resin composition, as shown in Figure 6, the exposed portion 111 is not removed by the developing treatment, while the unexposed portion 112 (see Figure 5) is removed. The exposed portion 111 of the second composition layer 110 remaining after development may have the same planar shape as the mask pattern of the light-transmitting portion 410 (see Figure 5) of the mask 400 used in step (IV).

[0202] The development method typically involves a wet development method in which the second composition layer 110 is brought into contact with the developer. An alkaline aqueous solution is usually used as the developer.

[0203] Examples of alkaline aqueous solutions used as developing solutions include aqueous solutions of alkali metal compounds. Examples of alkali metal compounds include alkali metal hydroxides such as lithium hydroxide, sodium hydroxide, and potassium hydroxide; alkali metal carbonates or bicarbonates such as sodium carbonate and sodium bicarbonate; alkali metal phosphates such as sodium phosphate and potassium phosphate; and alkali metal pyrophosphates such as sodium pyrophosphate and potassium pyrophosphate. Examples of alkaline aqueous solutions include aqueous solutions of organic bases that do not contain metal ions, such as tetraalkylammonium hydroxide. One type of alkaline aqueous solution may be used alone, or two or more types may be used in combination. Among these, alkali metal carbonates or bicarbonates are preferred from the viewpoint of obtaining the effects of the present invention in particular, and sodium carbonate is more preferred.

[0204] The developing solution may contain additives such as surfactants and defoamers, if necessary, to improve the developing action.

[0205] The development time is preferably 10 seconds to 5 minutes. The temperature of the developer solution during development is not particularly specified, but is preferably 20°C or higher, preferably 50°C or lower, and more preferably 40°C or lower.

[0206] Examples of development methods include the paddle method, spray method, immersion method, brushing method, slapping method, and ultrasonic method. Among these, the spray method is suitable for improving resolution. When using the spray method, a spray pressure of 0.05 MPa to 0.3 MPa is preferred.

[0207] After development using the developer, the second composition layer 110 may be rinsed. Rinsing is preferably performed with a solvent different from the developer. For example, rinsing may be performed using the same type of solvent as that contained in the core resin composition, or water. The rinsing time is preferably 5 seconds to 1 minute.

[0208] Furthermore, after development using a developer, desmear treatment may be performed to remove unexposed areas that could not be removed by development. Desmear treatment may be carried out according to various methods known to those skilled in the art that are used in the manufacture of printed circuit boards.

[0209] A method for manufacturing an optical waveguide according to one embodiment of the present invention includes a step (VI) for curing the second composition layer 110 after step (V). This step (VI) typically includes heat treatment of the second composition layer 110. The heat treatment conditions may be selected according to the type and amount of resin components in the photosensitive resin composition of the present invention. For example, the heat treatment conditions in step (VI) may be the same as the heat treatment conditions for the first composition layer 210 in step (II).

[0210] Figure 7 is a schematic cross-sectional view illustrating step (VI) of a method for manufacturing an optical waveguide according to one embodiment of the present invention. By curing the second composition layer 110 in step (VI), a core layer 100 as a cured second composition layer is obtained on the lower cladding layer 220, as shown in Figure 7.

[0211] Figure 8 is a schematic cross-sectional view illustrating step (VII) of a method for manufacturing an optical waveguide according to one embodiment of the present invention. As shown in Figure 8, the method for manufacturing an optical waveguide according to one embodiment of the present invention includes step (VII), after step (VI), a third composition layer 230 containing a cladding resin composition, on the core layer 100. The third composition layer 230 is usually formed to cover the entire surface of the circumferential surface of the core layer 100 that is not in contact with the lower cladding layer 220. Therefore, the third composition layer 230 is formed to cover the core layer 100 and is also formed on the lower cladding layer 220.

[0212] There are no particular restrictions on the method for forming the third composition layer 230. For example, the third composition layer 230 may be formed by applying the cladding resin composition onto the core layer 100 (and, if necessary, onto the lower cladding layer 220). The application of the cladding resin composition for forming the third composition layer 230 can be carried out in the same manner as the application of the cladding resin composition for forming the first composition layer 210. Furthermore, after the application of the cladding resin composition, the third composition layer 230 may be dried if necessary. The drying of the third composition layer 230 can be carried out using the same method and conditions as the drying of the first composition layer 210.

[0213] The third composition layer 230 may be formed, for example, using a cladding resin sheet. Specifically, the third composition layer 230 can be formed on the core layer 100 by laminating the photosensitive resin composition layer of the cladding resin sheet to the core layer 100 (and, if necessary, the lower cladding layer 220). Lamination of the cladding resin sheet for forming the third composition layer 230 can be carried out in the same manner as lamination of the cladding resin sheet for forming the first composition layer 210. When the third composition layer 230 is formed using a cladding resin sheet with a support, the support may be peeled off at any step.

[0214] The third composition layer 230 formed on the core layer 100 in step (VII) usually contains a cladding resin composition, and preferably contains only a cladding resin composition.

[0215] A method for manufacturing an optical waveguide according to one embodiment of the present invention includes a step (VIII) of curing the third composition layer 230 after step (VII). The effect of the third resin composition layer 230 in step (VIII) can usually be carried out in the same way as the curing of the first composition layer 210.

[0216] Figure 9 is a schematic cross-sectional view illustrating step (VIII) of a method for manufacturing an optical waveguide according to one embodiment of the present invention. By curing the third composition layer 230 in step (VIII), a cured third composition layer 240 is obtained on the core layer 100, as shown in Figure 9. This cured third composition layer 240 forms a part of the cladding layer 200 and may hereafter be referred to as the "upper cladding layer" 240. The cladding layer 200 is then formed from this upper cladding layer 240 and the lower cladding layer 220. Therefore, an optical waveguide 10 can be obtained comprising a cladding layer 200 including the lower cladding layer 220 and the upper cladding layer 240, and a core layer 100 provided within this cladding layer 200.

[0217] The method for manufacturing the optical waveguide 10 may include any additional steps in addition to the steps described above.

[0218] The method for manufacturing the optical waveguide 10 may include, for example, a step of forming a protective layer (not shown). Alternatively, the method for manufacturing the optical waveguide 10 may include, for example, a step of dicing the manufactured optical waveguide 10.

[0219] The manufacturing method for the optical waveguide 10 may involve repeatedly performing the steps described above. For example, by repeatedly performing steps (I) to (XI), a multilayer optical waveguide having alternating core layers and cladding layers in the thickness direction may be manufactured on the substrate 300.

[0220] [Photoelectric mixed-signal substrate] An optoelectronic mixed-signal substrate according to one embodiment of the present invention includes the optical waveguide described above. Typically, an optoelectronic mixed-signal substrate includes an optical waveguide and an electrical circuit board. The electrical circuit board may include electronic components and wiring connected to the electronic components. Examples of electronic components include passive components such as capacitors, inductors, and resistors; active components such as semiconductor chips; and so on. The optical waveguide and the wiring of the electrical circuit board may be connected via a photoelectric conversion element. The photoelectric conversion element may include a combination of a light-emitting element capable of converting electricity into light (e.g., a surface-emitting light-emitting diode) and a light-receiving element capable of converting light into electricity (e.g., a photodiode). Furthermore, the optoelectronic mixed-signal substrate may include optical elements such as mirrors for adjusting the optical path.

[0221] A preferred example of an optoelectronic hybrid substrate is one that includes a chip formed by creating an optical integrated circuit on a silicon wafer. This chip is expected to be put into practical use early on using silicon photonics, and is anticipated to be mounted, for example, in semiconductor packages. An optoelectronic hybrid substrate containing this chip includes, for example, an electrical circuit board, a chip mounted on the electrical circuit board, and an optical waveguide. The optical waveguide can be used to connect the wiring of the electrical circuit board to the chip, or to connect multiple chips.

[0222] In chips manufactured using silicon photonics, light with wavelengths of 1310 nm and 1550 nm is commonly used, with 1310 nm being particularly prevalent (Sho Yoshida, Daisuke Suganuma, Takaaki Ishigure, "Fabrication and Low-Loss Improvement of Single-Mode Polymer Waveguides by Mosquito Method," 28th Spring Conference of the Japan Society for Electronics Packaging, 2014). Therefore, it is preferable that the optical waveguide is capable of transmitting light with wavelengths of 1310 nm and 1550 nm or close to them, for example, it is preferable that it is capable of transmitting light with wavelengths of 1300 nm to 1320 nm. According to the optical waveguide of the embodiment described above, it is possible to transmit light of these wavelengths.

[0223] Generally, single-mode optical waveguides can achieve faster transmission speeds than multi-mode waveguides. Therefore, from the viewpoint of high-speed transmission, single-mode optical waveguides are preferred as optical waveguides applied to optical-electric mixed-signal circuits. In single-mode optical waveguides, it is preferable to have a small core layer width. For example, it is preferable to form a core layer with a width of 10 μm or less, or 5 μm or less. Furthermore, optical waveguides with such small core layers are also preferable from the viewpoint of increasing the degree of freedom in package design when the optical waveguide is applied to a semiconductor package. According to the optical waveguide of the embodiment described above, it is possible to reduce the width of the core layer as described above.

[0224] On the other hand, when connecting multiple optical-electric mixed-signal substrates, these substrates may be connected via optical fibers. For example, multiple optical-electric mixed-signal substrates may be installed in a rack and connected to each other with optical fibers. Multimode optical fibers are the mainstream for connecting substrates in this way. Therefore, from the standpoint of enabling connection with such optical fibers, a multimode optical waveguide may be adopted as the optical waveguide provided in the optical-electric mixed-signal substrate.

[0225] From the standpoint of increasing versatility, it is desirable that the optical waveguide be applicable to both single-mode and multi-mode applications. Furthermore, it is desirable to reduce the minimum width of the core layer of these optical waveguides to increase the degree of freedom in the line width of the core layer. According to the optical waveguide of the embodiment described above, by using the photosensitive resin composition of the present invention for the core, a fine core can be formed and the occurrence of surface irregularities of the core can be suppressed, so the minimum width of the core layer can be reduced. In addition, according to the optical waveguide of the embodiment described above, both single-mode and multi-mode optical waveguides can be obtained. Therefore, the optical waveguide of the embodiment described above is applicable to a wide range of applications. And, while being applicable to such a wide range of applications, it can suppress optical transmission loss, so the optical waveguide of the embodiment described above is suitable for application to optoelectronic mixed-signal substrates. [Examples]

[0226] The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. In the following description, "parts" and "%" refer to "parts by mass" and "mass%" respectively, unless otherwise specified. Furthermore, the operations described below were carried out in ambient air at normal temperature and pressure (23°C and 1 atm), unless otherwise specified.

[0227] <Synthesis Example 1: Synthesis of resins containing carboxyl groups and ethylenic double bonds> 325 parts of epoxy resin ("ESN-475V", manufactured by Nippon Steel Chemical & Material Co., Ltd.) having a naphthol aralkyl skeleton with an epoxy equivalent weight of 325330 g / eq. were placed in a flask equipped with a gas inlet tube, stirrer, condenser, and thermometer. 340 parts of carbitol acetate were added and heated until dissolved. 0.46 parts of hydroquinone and 1 part of triphenylphosphine were then added. This mixture was heated to 95-105°C, and 72 parts of acrylic acid were gradually added dropwise, reacting for 16 hours. The reaction product was cooled to 80-90°C, 80 parts of tetrahydrophthalic anhydride were added, reacted for 8 hours, and then cooled. The amount of solvent was adjusted to obtain a resin solution (non-volatile content 70%) with a solid acid value of 60 mg KOH / g. The weight-average molecular weight was 1000. The naphthol aralkyl skeleton contained in the obtained naphthol aralkyl skeleton-containing ester-type acid-modified epoxy acrylate resin was present as a repeating unit, accounting for 55% of the total mass of one molecule.

[0228] <Manufacturing Example 1: Manufacturing of Cladding Resin Compositions> 25 parts of naphthol aralkyl skeleton-containing ester-type acid-modified epoxy acrylate resin (non-volatile content 70%) obtained in Synthesis Example 1, 10 parts of dicyclopentadiene-type epoxy resin (DIC Corporation "HP-7200H", epoxy equivalent 270 g / eq.), 1.3 parts of photopolymerization initiator (IGM Corporation "Omnirad 379EG"), 10 parts of reactive diluent (Nippon Kayaku Co., Ltd. "DPHA", dipentaerythritol hexaacrylate), and spherical silica (Admatex Corporation "180nmSX-C1", specific surface area 20 m²) surface-treated with an amino-based silane coupling agent. 230 parts of the synthetic resin particles (average particle size: 0.2 μm) were mixed with 10 parts of methyl ethyl ketone, and a varnish-like resin composition was prepared using a high-speed rotary mixer.

[0229] <Example 1> 25 parts of the naphthol aralkyl skeleton-containing ester type acid-modified epoxy acrylate resin (non-volatile content: 70%) obtained in Synthesis Example 1, 10 parts of a dicyclopentadiene type epoxy resin (“HP-7200H” manufactured by DIC Corporation, epoxy equivalent: 270 g / eq.), 1.3 parts of a photopolymerization initiator (“Omnirad 379EG” manufactured by IGM), 10 parts of a photosensitizer (“Omnipol ASA” manufactured by IGM), 10 parts of a reactive diluent (“DPHA” manufactured by Nippon Kayaku Co., Ltd., dipentaerythritol hexaacrylate), and 1 part of methyl ethyl ketone were mixed, and a varnish-like resin composition was prepared using a high-speed rotary mixer.

[0230] <Examples 2 to 12, Comparative Examples 1 to 3: Production of Photosensitive Resin Compositions> A varnish-like photosensitive resin composition was prepared in the same manner as in Example 1, except that the components were mixed with the formulation compositions shown in the following table. In the table, the blending amounts of the respective components are in parts by mass and represent the actual amounts used.

[0231]

Table 1

[0232] The abbreviations, etc. in the table are as follows. (Component (A))<(0000912)>· HP-7200H: Dicyclopentadiene type epoxy resin (“HP-7200H” manufactured by DIC Corporation, epoxy equivalent: 270 g / eq.) <(0000913)>· HP-4710: Naphthalene type tetrafunctional epoxy resin (“HP-4710” manufactured by DIC Corporation, epoxy equivalent: 170 g / eq.) <(0000914)>· N-673: Cresol novolak type epoxy resin (“N-673” manufactured by DIC Corporation, epoxy equivalent: approximately 210 g / eq.) <(0000915)>(Component (B)) <(0000916)>• Synthesis Example 1: A resin containing carboxyl groups and ethylenic double bonds synthesized in Synthesis Example 1, with a non-volatile content of 70% and containing a naphthol aralkyl skeleton at 55% of the total mass of one molecule. • ZCR-1569H: Biphenyl skeleton-containing acid-modified epoxy acrylate resin (manufactured by Nippon Kayaku Co., Ltd., "ZCR-1569H", acid value 98 mg KOH / g, non-volatile content 70%, solvent PGMEA, molecular weight 4500) (C) Component • Omnirad 379EG: A compound represented by the following structure (manufactured by IGM, molecular weight 380.5, 2-dimethylamino-2-(4-methyl-benzyl)-1-(4-morpholin-4-yl-phenyl)-butan-1-one, CAS 119344-86-4) [ka] • Irgacure OXE-02: A compound represented by the following structure (manufactured by BASF, molecular weight 412.5, ethanone, 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazol-3-yl]-, 1-(o-acetyloxime)) [ka] • Omnirad 819: A compound represented by the structure shown below (manufactured by IGM, molecular weight 418.5, Bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide) [ka] • Omnipol TP: A compound represented by the following structure (manufactured by IGM, molecular weight 900 or higher). In the formula, a, b, and c each represent an integer between 1 and 10. [ka] • Omnipol 910: A compound represented by the following structure (manufactured by IGM, molecular weight 850 or higher). In the formula, d represents an integer from 1 to 10. [ka] (D) Component ·Omnipol ASA: Manufactured by IGM, molecular weight approximately 510, Poly(ethylene glycol)bis(p-dimethylaminobenzoate), where r1 represents 3 or 4.

Chem.

Chem.

Chem.

Chem.

[0233] <Manufacture of Resin Sheet> Using the photosensitive resin compositions produced in Examples 1 to 12 and Comparative Examples 1 to 3 described above, multiple resin sheets having photosensitive resin composition layers of different thicknesses were manufactured by the following method.

[0234] A polyethylene terephthalate film (Toray Industries, Ltd. "Lumirror T6AM", 38 μm thick, softening point 130°C) was prepared as a support. The photosensitive resin compositions produced in Production Example 1, Examples 1-12, and Comparative Examples 1-3 were uniformly applied to the support using a die coater so that the thickness of the photosensitive resin composition layer after drying was 5 μm or 10 μm, and the photosensitive resin composition layer was formed by drying at 80°C to 110°C (maximum temperature 110°C) for 6 minutes. Next, a cover film (biaxially oriented polypropylene film, Oji F-Tex Corporation "MA-411") was placed on the surface of the photosensitive resin composition layer and laminated at 80°C to produce a resin sheet with a three-layer structure of support / photosensitive resin composition layer / cover film.

[0235] A polyethylene terephthalate film (Toray Industries, Ltd. "Lumirror T6AM", 38 μm thick, softening point 130°C) was prepared as a support. The resin composition produced in Production Example 1 was uniformly applied using a die coater so that the thickness of the dried resin composition layer was 5 μm, 10 μm, or 20 μm, and dried at 80°C to 110°C (maximum temperature 110°C) for 6 minutes to form a photosensitive resin composition layer. Next, a cover film (biaxially oriented polypropylene film, Oji F-Tex Corporation "MA-411") was placed on the surface of the photosensitive resin composition layer and laminated at 80°C to produce a resin sheet with a three-layer structure of support / photosensitive resin composition layer / cover film.

[0236] [Evaluation of core formation ability] (Evaluation of minimum wire formation width) A glass epoxy substrate (copper-clad laminate) with an 18 μm thick copper layer was prepared by roughening the copper layer with a surface treatment agent containing an organic acid (CZ8100, manufactured by MEC). A resin sheet with a 5 μm thick photosensitive resin composition layer, manufactured using the resin composition prepared in Manufacturing Example 1, was laminated onto the substrate at 80°C, and the support was peeled off to form the photosensitive resin composition layer. Subsequently, ultraviolet exposure was performed using a projection exposure apparatus (UFX-2240, manufactured by Ushio Inc.) at an exposure energy that resulted in 8 steps of gloss remaining on a 41-step tablet. A quartz glass mask without an exposure pattern was used. After standing at room temperature for 30 minutes, the support was peeled off. The entire surface of the photosensitive resin composition layer was spray-developed with a 1% by mass aqueous sodium carbonate solution at 30°C at a spray pressure of 0.2 MPa for 1 minute. After spray development, 2 J / cm 2 By irradiating the copper-clad laminate with ultraviolet light and then performing a heat treatment at 170°C for 1 hour in a nitrogen atmosphere, a lower cladding layer was formed on the copper-clad laminate.

[0237] The cover film was peeled off from a resin sheet having a 10 μm thick photosensitive resin composition layer, which was manufactured using the photosensitive resin compositions produced in each of the above-described examples and comparative examples. The resin sheet was placed on the lower cladding layer so that the photosensitive resin composition layer of the resin sheet was in contact with the lower cladding layer, and the layers were laminated using a vacuum laminator (Nikko Materials Co., Ltd. "VP160") to form a photosensitive resin composition layer on the lower cladding layer. The lamination conditions were a vacuuming time of 30 seconds, a pressing temperature of 100°C, a pressing pressure of 0.7 MPa, and a pressing time of 30 seconds. This resulted in a laminate comprising a copper-clad laminate, a lower cladding layer, and a resin sheet in that order. Subsequently, the support was peeled off to expose the photosensitive resin composition layer.

[0238] A photosensitive resin composition layer was exposed to ultraviolet light using a projection exposure apparatus (UFX-2240, manufactured by Ushio Inc.) at an exposure energy that resulted in 8 remaining gloss steps on a 41-step tablet. Exposure was performed using a quartz glass mask having a first mask pattern that drew straight lines at L / S (line / space) 10 μm / 10 μm, a second mask pattern that drew straight lines at L / S (line / space) 5 μm / 5 μm, and a third mask pattern that drew straight lines at L / S (line / space) 3 μm / 3 μm. After exposure, the support was left to stand at room temperature for 30 minutes before being peeled off. The entire surface of the photosensitive resin composition layer was spray-developed with a 1% by mass aqueous sodium carbonate solution at 30°C at a spray pressure of 0.2 MPa for 1 minute. After spray development, the temperature was 2 J / cm². 2 By irradiating the sample with ultraviolet light and then performing a heat treatment at 170°C for 1 hour in a nitrogen atmosphere, a sample was obtained that had a copper-clad laminate, a lower cladding layer, and a line layer (a layer formed from cured resin composition) in that order.

[0239] The obtained samples were observed using a scanning electron microscope (SEM) (magnification 2000x), and the minimum nanowire formation width (the width of the narrowest line layer among the formed line layers) was measured. The aspect ratio was calculated by dividing the line layer thickness by the minimum nanowire formation width. The minimum nanowire formation width for core formation was evaluated according to the following criteria. Line width refers to the width of the line layer. ◎: All line layers with a line width of 10 μm or less have an aspect ratio of 1 or greater. ○: For all line layers with a line width of 10 μm or less, the aspect ratio is 0.8 or greater and less than 1. △: For all line layers with a line width of 10 μm or less, the aspect ratio is 0.6 or greater and less than 0.8. ×: At least one aspect ratio of a line layer with a line width of 10 μm or less is less than 0.6.

[0240] (Evaluation of surface irregularities) The line layer, in which the minimum fine wire formation width was measured, was observed using a scanning electron microscope (SEM) (magnification 2000x), and the surface condition was evaluated according to the following criteria. ○: The surface of the line layer is smooth and free of irregularities. ×: The surface of the line layer has irregularities.

[0241] [Measurement of optical transmission loss] (1-1. Formation of the lower cladding layer) A cover film was peeled off a resin sheet having a 10 μm thick photosensitive resin composition layer, which was manufactured using the resin composition produced in Manufacturing Example 1. The resin sheet was placed on a 4-inch silicon wafer so that the photosensitive resin composition layer and the silicon wafer were in contact, and the layers were laminated using a vacuum laminator (Nikko Materials Co., Ltd. "VP160"). The lamination conditions were a vacuum evacuation time of 30 seconds, a bonding temperature of 100°C, a bonding pressure of 0.7 MPa, and a pressing time of 30 seconds. After that, the support was peeled off to obtain an intermediate laminate I comprising a silicon wafer and a photosensitive resin composition layer.

[0242] The photosensitive resin composition layer of the intermediate laminate I was exposed to ultraviolet light using a projection exposure apparatus (UFX-2240, manufactured by Ushio Inc.) at an exposure energy that resulted in 8 remaining glossy step steps on a 41-step tablet. After exposure, 2 J / cm 2 Ultraviolet irradiation was performed. Intermediate laminate I was placed in a clean oven and heated from room temperature to 170°C. After reaching 170°C, a heat treatment was performed for 60 minutes under a nitrogen atmosphere to cure the photosensitive resin composition layer. The curing of the photosensitive resin composition layer formed a lower cladding layer, yielding intermediate laminate II comprising a silicon wafer and a lower cladding layer.

[0243] (1-2. Formation of the core layer) A cover film was peeled off a resin sheet having a 5 μm thick photosensitive resin composition layer, which was manufactured using the photosensitive resin compositions produced in the examples and comparative examples. The resin sheet was placed on the surface of the lower cladding layer of intermediate laminate II so that the photosensitive resin composition layer and the lower cladding layer were in contact, and lamination was performed using a vacuum laminator (Nikko Materials Co., Ltd. "VP160"). The lamination conditions were a vacuuming time of 30 seconds, a bonding temperature of 100°C, a bonding pressure of 0.7 MPa, and a pressing time of 30 seconds. After that, the support was peeled off to obtain intermediate laminate III having a silicon wafer, a base cladding layer, and a photosensitive resin composition layer in that order.

[0244] The photosensitive resin composition layer of the intermediate laminate III was exposed to ultraviolet light using a projection exposure apparatus (UFX-2240, manufactured by Ushio Inc.) at an exposure energy that resulted in 8 remaining glossy steps on a 41-step tablet. The exposure was performed using a quartz glass mask having a mask pattern capable of drawing multiple straight lines of 1 cm in length with an L / S (line / space) of 5 μm / 100 μm, a mask pattern capable of drawing multiple straight lines of 2 cm in length with an L / S (line / space) of 5 μm / 100 μm, and a mask pattern capable of drawing multiple straight lines of 3 cm in length with an L / S (line / space) of 5 μm / 100 μm. In the L / S of this quartz glass mask, the line corresponds to the width of the core layer, and the space corresponds to the spacing between core layers. After exposure, the mask was left to stand at room temperature for 30 minutes before the support was peeled off. The entire surface of the photosensitive resin composition layer was spray-developed with a 1% by mass aqueous sodium carbonate solution at 30°C at a spray pressure of 0.2 MPa for 1 minute. After spray development, the yield was 2 J / cm². 2 Ultraviolet irradiation was performed. Then, the intermediate laminate III was placed in a clean oven, heated from room temperature to 170°C, and after reaching 170°C, a 60-minute heat treatment was carried out under a nitrogen atmosphere to cure the photosensitive resin composition layer.

[0245] A core layer was formed by curing the photosensitive resin composition layer, resulting in an intermediate laminate IV comprising a silicon wafer, a lower cladding layer, and a core layer in that order.

[0246] (1-3. Formation of the upper cladding layer) A cover film was peeled off a resin sheet having a 20 μm thick photosensitive resin composition layer, which was manufactured using the resin composition produced in Manufacturing Example 1. The resin sheet was placed on the core layer of intermediate laminate IV so that the photosensitive resin composition layer and the core layer were in contact, and the laminate was constructed using a vacuum laminator (Nikko Materials "VP160"). The lamination conditions were a vacuuming time of 30 seconds, a bonding temperature of 100°C, a bonding pressure of 0.7 MPa, and a pressing time of 30 seconds. After that, the support was peeled off to obtain intermediate laminate V having a silicon wafer, a lower cladding layer, a core layer, and a photosensitive resin composition layer in that order. The photosensitive resin composition layer of the intermediate laminate V was subjected to ultraviolet exposure using a projection exposure apparatus (UFX-2240, manufactured by Ushio Inc.) at an exposure energy that resulted in 8 remaining glossy step steps on a 41-step tablet. After exposure, 2 J / cm² 2 Ultraviolet irradiation was performed. The intermediate laminate V was placed in a clean oven and heated from room temperature to 170°C. After reaching 170°C, a heat treatment was performed for 60 minutes under a nitrogen atmosphere to cure the photosensitive resin composition layer. The curing of the photosensitive resin composition layer formed an upper cladding layer, and a sample laminate was obtained having a silicon wafer, a lower cladding layer, a core layer, and an upper cladding layer in that order.

[0247] In this sample laminate, the combination of the lower cladding layer and the upper cladding layer constituted the cladding layer. Therefore, an optical waveguide was obtained that included the cladding layer and the core layer within the cladding layer. Furthermore, in this sample laminate, the core layer had linear patterns of lengths 1 cm, 2 cm, and 3 cm, corresponding to the mask pattern of the quartz glass mask, and the width (line width) and spacing (space) of the core layers included in these patterns matched the width (line width) and spacing (space) of the mask pattern.

[0248] [Evaluation of optical waveguides] (Measurement of optical transmission loss in a calibration optical system) The transmission loss of an optical system was measured using a configuration that excluded the test substrate and focusing module from the optical system used for measuring the transmission loss of the test substrate described later. Specifically, a calibration optical system was obtained by connecting a light source (1310 nm light source, THORLABS "LPSC-1310-FC") and a photodetector (Keysight optical power meter "N7742") via an optical fiber (incident fiber) on a vibration isolation table covered with a blackout curtain. The light source was emitted, and the intensity of the light entering the photodetector was measured by the photodetector to determine the loss of this calibration optical system.

[0249] (Preparation of the test circuit board) From the sample laminates prepared using the photosensitive resin compositions of the examples and comparative examples, the core layer and the surrounding cladding layer were cut out at the portion where the core layer was formed to obtain a test substrate equipped with an optical transmission path.

[0250] (Measurement of optical transmission loss) A test substrate was placed on a vibration isolation table covered with a blackout curtain. A focusing module (numerical aperture 0.18) was connected to one end (entry end) of the optical waveguide of the test substrate, and a light source (1310 nm light source, THORLABS "LPSC-1310-FC") was further connected to the focusing module via an optical fiber (entry fiber). Another focusing module (numerical aperture 0.18) was connected to the other end (exit end) of the optical waveguide of the test substrate, and a photodetector (Keysight optical power meter "N7742") was further connected to this focusing module via an optical fiber (exit fiber). Through the above operation, an optical system was obtained in which light emitted from the light source passes through the optical fiber (entry fiber), focusing module, optical waveguide, focusing module, and optical fiber (exit fiber) in that order before entering the photodetector. Hereafter, this optical system may be referred to as the sample optical system. The light source was illuminated, and the intensity of the light entering the photodetector was measured by the photodetector to determine the loss of the sample optical system.

[0251] The loss of the optical waveguide contained in the test substrate was determined by subtracting the loss of the calibration optical system from the loss of the sample optical system.

[0252] (Measurement of transmission loss (dB / cm) in optical waveguides) The optical waveguide loss was measured for optical waveguides of lengths 1 cm, 2 cm, and 3 cm. The measurement results were plotted on a coordinate system with the optical waveguide length on the horizontal axis and the optical waveguide loss on the vertical axis to obtain three coordinate points representing the measurement results. The approximate straight line between these three points was calculated using the least squares method, and the slope of this approximate straight line was determined as the loss per unit distance of the optical waveguide (transmission loss), and evaluated according to the following criteria. ○: Optical transmission loss is less than 1 dB / cm △: Optical transmission loss is between 1 dB / cm and less than 2 dB / cm ×: Optical transmission loss is 2 dB / cm or more

[0253] (Checking the mode) The photodetector was removed and replaced with an infrared camera (InGaAs camera with a 100x objective lens). The light source was activated, and the light emitted from the end of the optical fiber (output fiber) was photographed with the infrared camera. If only one perfectly circular edge of light was observed, it was determined to be single-mode. If multiple edges were observed, it was determined to be multi-mode. In the table, "S" means single mode and "M" means multi-mode.

[0254] [Measurement of absorbance of a solution of a photosensitive resin composition] Solutions of the photosensitive resin compositions prepared in Examples 1-11 and Comparative Examples 1-3 were prepared, and the absorbance of these solutions was measured by the following method. Specifically, a mixed solvent of MEK (methyl ethyl ketone) and cyclopentanone (MEK:pentanone = 1:1) was mixed with the photosensitive resin compositions of Examples 1-12 and Comparative Examples 1-3 to prepare a photosensitive resin composition solution with a concentration of 20% by mass. This solution was placed in a 1 cm quartz cell, and the absorbance Abs at a wavelength of 1310 nm was measured using a UV-Vis-Near-Infrared spectrophotometer (JASCO Corporation, V-770), and evaluated according to the following criteria. ○: Absorbance less than 0.0050 △: Absorbance is between 0.0050 and less than 0.0100 ×: Absorbance is 0.0100 or higher

[0255] [Table 2]

[0256] Examples 1 to 12, which use photosensitive resin compositions containing a combination of components (A) to (D), exhibit excellent core formation, suppression of surface irregularities in the line layer, and reduced optical transmission loss. In contrast, Comparative Examples 1 to 3, which do not contain component (D), show inferior core formation, surface irregularity, and optical transmission loss compared to Examples 1 to 12. [Explanation of Symbols]

[0257] 10 Optical waveguide 100 core layers 110 Second composition layer 111 Exposure area 112 Unexposed area 200 Clad layer 210 First composition layer 220 Cured first composition layer (lower cladding layer) 230 Third composition layer 240 Cured third composition layer (upper cladding layer) 300 Base material 400 masks 410 Translucent part 420 Light-shielding part

Claims

1. (A) Epoxy resin, (B) Resins containing carboxyl groups and ethylenic double bonds, (C) A photopolymerization initiator containing a structural unit represented by the following formula (C-1) and having a molecular weight of 420 or more, and (D) A photosensitive resin composition containing a photosensitizer having a molecular weight of 400 or more. 【Chemistry 1】 (In the formula, R1 represents an active light-absorbing group, and R2 independently represents a divalent hydrocarbon group. n represents an integer from 1 to 10. * represents a bond.)

2. The photosensitive resin composition according to claim 1, wherein R1 in formula (C-1) is an active light-absorbing group of either formula (i) or (ii) below. 【Chemistry 2】 (In the formula, * represents a bond.)

3. The photosensitive resin composition according to claim 1, wherein component (C) comprises a photopolymerization initiator represented by the following formula. 【Transformation 3】 (In the formula, d represents an integer between 1 and 10.)

4. The photosensitive resin composition according to claim 1, wherein component (B) comprises an acid-modified epoxy (meth)acrylate resin having a naphthol aralkyl skeleton.

5. Furthermore, the photosensitive resin composition according to claim 1, further comprising (E) an inorganic filler with an average particle size of 100 nm or less.

6. The photosensitive resin composition according to claim 1, wherein component (D) contains a tertiary amino group in the molecule.

7. The photosensitive resin composition according to claim 1, wherein component (D) contains an aminobenzoyl group in the molecule.

8. The photosensitive resin composition according to claim 1, wherein component (D) comprises a compound represented by the following formula (D-1). 【Chemistry 4】 (In the formula, R 41, R 42, R 45, and R 46 each independently represent an alkyl group having 1 to 6 carbon atoms, R 43 each independently represent a divalent group selected from the group consisting of an alkylene group having 1 to 6 carbon atoms, an oxygen atom, -NR-, and combinations thereof, R represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and R 44 represents a divalent group selected from the group consisting of an alkylene group having 1 to 6 carbon atoms, an oxygen atom, and combinations thereof. r represents an integer from 1 to 10.)

9. The photosensitive resin composition according to claim 1, wherein component (A) contains either a naphthalene skeleton-containing epoxy resin or a biphenyl skeleton-containing epoxy resin.

10. The photosensitive resin composition according to claim 1, for use in developing sodium carbonate.

11. A photosensitive resin composition according to claim 1, for use in manufacturing the core layer of an optical waveguide.

12. The device comprises a support and a photosensitive resin composition layer formed on the support, A resin sheet in which the photosensitive resin composition layer is made of the photosensitive resin composition according to any one of claims 1 to 11.

13. The resin sheet according to claim 12, wherein the thickness of the photosensitive resin composition layer is 1 μm or more and 15 μm or less.

14. A photosensitive resin composition set comprising a core photosensitive resin composition and a cladding resin composition, A photosensitive resin composition set comprising a photosensitive resin composition for cores, the photosensitive resin composition described in any one of claims 1 to 11.

15. It comprises a core layer and a cladding layer, An optical waveguide in which the core layer comprises a cured product of the photosensitive resin composition described in any one of claims 1 to 11.

16. The optical waveguide according to claim 15, capable of transmitting light with a wavelength of 1300 nm to 1320 nm.

17. The optical waveguide according to claim 15, which is a single-mode optical waveguide.

18. A photoelectric mixed-signal substrate equipped with an optical waveguide as described in claim 15.

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