Photosensitive resin composition

Abstract

To provide a photosensitive resin composition which enables manufacture of an optical waveguide that is excellent in core formability, suppresses occurrence of warpage, and has small absorbance.SOLUTION: A photosensitive resin composition contains (A) an epoxy resin, (B) a resin containing a carboxy group and an ethylenic double bond, and (C) a photopolymerization initiator, wherein the component (B) contains a structure the same as the component (A).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 optoelectronic 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 is increasing. Conventionally, semiconductor packages that support the core of this have been able to handle 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, in recent years, there has been an active effort 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).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] In particular, in data centers where high-speed transmission is required, research on the introduction of silicon photonics has been actively conducted. Silicon photonics is highly compatible with conventional LSI manufacturing processes. Therefore, by utilizing silicon photonics, it is expected that the formation of sub-nanometer-sized thin wire waveguides will be possible at low cost based on the technologies cultivated in electronic circuit integration technology.

[0005] For example, according to silicon photonics, it is expected to form an optical integrated circuit on a chip using a fine wire waveguide. When manufacturing an optoelectronic hybrid substrate on which this chip is mounted, in order to extract signal light from the fine wire waveguide in the chip to the outside of the chip and connect it to the wiring between chips, it is required to provide an optical waveguide on the optoelectronic hybrid substrate. From the viewpoint of efficiently forming a fine optical waveguide, it is desirable to form the optical waveguide with a cured product of a photosensitive resin composition. For this reason, it is desirable to have excellent core formability for forming fine wiring. However, when forming a fine optical waveguide, warping of the core layer may occur after the core layer is formed, and dimensional deviation may occur when forming the cladding layer thereafter. In addition, when the absorbance of the photosensitive resin composition is large, light may be difficult to transmit.

[0006] The present invention was devised in view of the above problems, and an object thereof is to provide a photosensitive resin composition capable of manufacturing an optical waveguide having excellent core formability, suppressed warping, and low absorbance; a resin sheet containing the photosensitive resin composition; a photosensitive resin composition set; an optical waveguide; and an optoelectronic hybrid substrate.

Means for Solving the Problems

[0007] The present inventor intensively studied to solve the above problems. As a result, the present inventor found that by using a photosensitive resin composition containing a combination of (A) an epoxy resin, (B) a resin containing a carboxy group and an ethylenic double bond having the same structure as the component (A), and (C) a photopolymerization initiator, an optical waveguide having excellent core formability, suppressed warping, and low absorbance can be manufactured, and completed the present invention.

[0008] That is, the present invention includes the following. [1] (A) An epoxy resin, (B) A resin containing a carboxy group and an ethylenic double bond, and (C) A photopolymerization initiator, and the component (B) contains the same skeleton as the component (A), a photosensitive resin composition. (B) component contains the same skeleton as the (A) component, a photosensitive resin composition. [2] The photosensitive resin composition according to [1], wherein the component (B) contains the same aromatic skeleton as the component (A). [3] The photosensitive resin composition according to [1] or [2], wherein the component (B) contains the same skeleton as the component (A), and the skeleton accounts for 5% or more of the total mass of one molecule of the component (B). [4] The photosensitive resin composition according to [2], wherein the aromatic skeleton contains a polycyclic aromatic skeleton. [5] The photosensitive resin composition according to any one of [1] to [4], wherein the component (C) contains a photoinitiator having a molecular weight of 420 or more (C1). [6] The photosensitive resin composition according to any one of [1] to [5], wherein the component (C) contains a photoinitiator having a molecular weight of less than 420 (C2). [7] The photosensitive resin composition according to [6], wherein the component (C2) contains any one of an oxime ester-based photoinitiator, an α-amino ketone-based photoinitiator, and an acylphosphine-based photoinitiator. [8] The photosensitive resin composition according to any one of [1] to [7], further containing (D) a photosensitizer. [9] The photosensitive resin composition according to any one of [1] to [8], further containing (E) an inorganic filler having an average particle size of 100 nm or less.

[10] The photosensitive resin composition according to any one of [1] to [9], which is for sodium carbonate development.

[11] The photosensitive resin composition according to any one of [1] to

[10] , which is for manufacturing the core layer of an optical waveguide.

[12] A resin sheet having a support and a photosensitive resin composition layer formed on the support and composed of the photosensitive resin composition according to any one of [1] to

[11] .

[13] The resin sheet according to

[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 including a photosensitive resin composition for a core and a resin composition for a clad, The photosensitive resin composition set, wherein the photosensitive resin composition for a core includes the photosensitive resin composition according to any one of [1] to

[11] .

[15] Having a core layer and a clad layer, An optical waveguide in which a core layer contains a cured product of the photosensitive resin composition according to any one of [1] to

[11] .

[16] The optical waveguide according to

[15] , which is capable of transmitting light having a wavelength of 1300 nm to 1320 nm.

[17] The optical waveguide according to

[15] or

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

[18] An optoelectronic hybrid substrate including the optical waveguide according to any one of

[15] to

[17] . [Effect of the Invention]

[0009] According to the present invention, there can be provided a photosensitive resin composition excellent in core formability, capable of suppressing the occurrence of warpage, and having a small absorbance; a photosensitive resin composition set including the photosensitive resin composition; an optical waveguide; and an optoelectronic hybrid substrate. [Brief Description of the Drawings]

[0010]

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Figure 7

Figure 8

Figure 9

[0011] Hereinafter, the present invention will be described in detail with reference to embodiments and examples. However, the present invention is not limited to the embodiments and examples given below, and can be arbitrarily modified and implemented 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 carboxy group and an ethylenic double bond, and (C) a photopolymerization initiator, and the component (B) contains the same skeleton as the component (A). According to the photosensitive resin composition of the present invention, an optical waveguide excellent in core formability, suppressed in warpage generation, and having a small absorbance can be manufactured. Further, in the present invention, it is usually possible to obtain a cured product having a small optical transmission loss and a low coefficient of thermal expansion (CTE) on average.

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

[0014] In the following description, 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. In the present invention, unless otherwise specified, the content of each component in the photosensitive resin composition is a value based on 100% by mass of the non-volatile components in the photosensitive resin composition.

[0015] <(A) Epoxy resin> The photosensitive resin composition contains, as component (A), an (A) epoxy resin. The (A) epoxy resin is a curable resin having an epoxy group.

[0016] Examples of the (A) epoxy resin include a bixylenol type epoxy resin; 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 resin; novolac type epoxy resins such as tris-phenol type epoxy resin and phenol novolac type epoxy resin; tert-butyl-catechol type epoxy resin; naphthalene skeleton-containing epoxy resins such as naphthalene type epoxy resin, naphthol type epoxy resin, naphthylene ether type epoxy resin, and naphthol novolac type epoxy resin; anthracene type epoxy resin; glycidylamine type epoxy resin; glycidyl ester type epoxy resin; cresol novolac type epoxy resin; phenol aralkyl type epoxy resin; biphenyl skeleton-containing epoxy resin; linear aliphatic epoxy resin; epoxy resin having a butadiene structure; alicyclic epoxy resin; heterocyclic epoxy resin; spiro ring-containing epoxy resin; cyclohexane type epoxy resin; cyclohexanedimethanol type epoxy resin; trimethylol type epoxy resin; tetraphenylethane type epoxy resin; isocyanurate type epoxy resin; phenolphthalimide type epoxy resin, etc. Among them, from the viewpoint of significantly obtaining the effects of the present invention, the (A) epoxy resin preferably contains either a naphthalene skeleton-containing epoxy resin or a biphenyl skeleton-containing epoxy resin. The (A) epoxy resin may be used alone or in combination of two or more.

[0017] (A) From the viewpoint of significantly obtaining the effects of the present invention, the epoxy resin preferably contains an epoxy resin containing an aromatic skeleton. The aromatic skeleton is a chemical structure generally defined as aromatic, and includes a polycyclic aromatic skeleton containing a condensed ring and an aromatic heterocyclic skeleton, and a polycyclic aromatic skeleton is preferred. Examples of the aromatic skeleton include aromatic skeletons containing a phenol skeleton such as bisphenol A skeleton, bisphenol F skeleton, bisphenol S skeleton, bisphenol AF, trisphenol skeleton, tert-butyl-catechol skeleton, cresol novolak skeleton, and phenol novolak skeleton; aromatic skeletons containing a naphthalene skeleton such as naphthol novolak skeleton, naphthalene skeleton, naphthol skeleton, and naphthylene ether skeleton; aromatic skeletons containing an anthracene skeleton; and aromatic skeletons containing a bixylenol skeleton. Among them, from the viewpoint of particularly significantly obtaining the effects of the present invention, an aromatic skeleton containing a naphthalene skeleton is preferred.

[0018] Examples of epoxy resins containing an aromatic skeleton include aromatic skeleton-containing epoxy resins containing a phenol skeleton, such as bisphenol A type epoxy resins, bisphenol F type epoxy resins, bisphenol S type epoxy resins, bisphenol AF type epoxy resins, trisphenol type epoxy resins, tert-butyl-catechol type epoxy resins, cresol novolac type epoxy resins, and phenol novolac type epoxy resins; aromatic skeleton-containing epoxy resins containing a naphthalene skeleton, such as naphthol novolac type epoxy resins, naphthalene type epoxy resins, naphthol type epoxy resins, and naphthylene ether type epoxy resins; Examples of such epoxy resins include thracene type epoxy resins, bixylenol type epoxy resins, glycidylamine type epoxy resins having an aromatic skeleton, glycidyl ester type epoxy resins having an aromatic skeleton, biphenyl type epoxy resins, linear aliphatic epoxy resins having an aromatic skeleton, epoxy resins having a butadiene structure having an aromatic skeleton, alicyclic epoxy resins having an aromatic skeleton, heterocyclic epoxy resins, spiro ring-containing epoxy resins having an aromatic skeleton, cyclohexanedimethanol type epoxy resins having an aromatic skeleton, trimethylol type epoxy resins having an aromatic skeleton, and tetraphenylethane type epoxy resins having an aromatic skeleton. Among these, aromatic skeleton-containing epoxy resins containing a naphthalene skeleton are preferred from the viewpoint of obtaining the effects of the present invention more significantly.

[0019] The photosensitive resin composition of the present invention preferably contains, as the epoxy resin (A), an epoxy resin having two or more epoxy groups in one molecule. The proportion of the epoxy resin having two or more epoxy groups in one molecule relative to 100% by mass of the epoxy resin (A) is preferably 50% by mass or more, more preferably 60% by mass or more, and particularly preferably 70% by mass or more.

[0020] (A) Epoxy resins include solid epoxy resins (hereinafter sometimes referred to as "solid epoxy resins") at a temperature of 20°C and liquid epoxy resins (hereinafter sometimes referred to as "liquid epoxy resins") at a temperature of 20°C. The photosensitive resin composition of the present invention may contain only a liquid epoxy resin as the (A) epoxy resin, or may contain only a solid epoxy resin, or may contain both a liquid epoxy resin and a solid epoxy resin, but it is particularly preferable to contain only a solid epoxy resin.

[0021] As the solid epoxy resin, a solid epoxy resin having 3 or more epoxy groups in one molecule is preferable, and an aromatic solid epoxy resin having 3 or more epoxy groups in one molecule is more preferable.

[0022] Examples of the solid epoxy resin include bixylenol type epoxy resin, naphthalene type epoxy resin, naphthalene type tetrafunctional epoxy resin, naphthol novolak type epoxy resin, cresol novolak type epoxy resin, dicyclopentadiene type epoxy resin, tris-phenol type epoxy resin, naphthol type epoxy resin, biphenyl type epoxy resin, naphthylene ether type epoxy resin, anthracene type epoxy resin, bisphenol A type epoxy resin, bisphenol AF type epoxy resin, phenol aralkyl type epoxy resin, tetraphenylethane type epoxy resin, and phenol phthalimide type epoxy resin. Any of a naphthalene skeleton-containing epoxy resin and a biphenyl skeleton-containing epoxy resin is more preferable, and any of a naphthalene type epoxy resin, a naphthol type epoxy resin, and a biphenyl type epoxy resin is even more preferable.

[0023] Specific examples of the solid epoxy resin include "HP4032H" (naphthalene-type epoxy resin) manufactured by DIC Corporation; "HP-4700", "HP-4710" (naphthalene-type tetrafunctional epoxy resin) manufactured by DIC Corporation; "N-690" (cresol novolak-type epoxy resin) manufactured by DIC Corporation; "N-695" (cresol novolak-type epoxy resin) manufactured by DIC Corporation; "HP-7200", "HP-7200HH", "HP-7200H", "HP-7200L" (dicyclopentadiene-type epoxy resin) manufactured by DIC Corporation; "EXA-7311", "EXA-7311-G3", "EXA-7311-G4", "EXA-7311-G4S", "HP6000" (naphthylene ether-type epoxy resin) manufactured by DIC Corporation; "EPPN-502H" (trisphenol-type epoxy resin) manufactured by Nippon Kayaku Co., Ltd.; "NC7000L" (naphthol novolak-type epoxy resin) manufactured by Nippon Kayaku Co., Ltd.; "NC3000H", "NC3000", "NC3000L", "NC3000FH", "NC3100" (biphenyl-type epoxy resin) manufactured by Nippon Kayaku Co., Ltd.; "ESN475V", "ESN4100V" (naphthalene-type epoxy resin) 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", "YL7890" (bixylenol-type epoxy resin) manufactured by Mitsubishi Chemical Corporation; "YL6121" (biphenyl-type epoxy resin) manufactured by Mitsubishi Chemical Corporation; "YX8800" (anthracene-type epoxy resin) manufactured by Mitsubishi Chemical Corporation; "YX7700" (phenol aralkyl-type epoxy resin) manufactured by Mitsubishi Chemical Corporation; "PG-100", "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; "WHR991S" (phenolphthalimide-type epoxy resin) manufactured by Nippon Kayaku Co., Ltd., and the like.These may be used alone or in combination of two or more.

[0024] As the liquid epoxy resin, a liquid epoxy resin having two or more epoxy groups in one molecule is preferred.

[0025] As the liquid epoxy resin, glycidol type epoxy resin, bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol AF type epoxy resin, naphthalene type epoxy resin, glycidyl ester type epoxy resin, glycidyl amine type epoxy resin, phenol novolac type epoxy resin, alicyclic epoxy resin having an ester skeleton, cyclohexanedimethanol type epoxy resin, cyclic aliphatic glycidyl ether, and epoxy resin having a butadiene structure are preferred.

[0026] Specific examples of the liquid epoxy resin include "EX-992L" manufactured by Nagase ChemteX Corporation, "YX7400" manufactured by Mitsubishi Chemical Corporation, "HP4032", "HP4032D", "HP4032SS" (naphthalene-type epoxy resin) manufactured by DIC Corporation; "828US", "jER828EL", "828EL", "825", "Epicoat 828EL" (bisphenol A-type epoxy resin) manufactured by Mitsubishi Chemical Corporation; "jER807", "1750" (bisphenol F-type epoxy resin) manufactured by Mitsubishi Chemical Corporation; "jER152" (phenol novolak-type epoxy resin) manufactured by Mitsubishi Chemical Corporation; "630", "630LSD", "604" (glycidylamine-type epoxy resin) manufactured by Mitsubishi Chemical Corporation; "ED-523T" (glycerol-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" (a mixture of bisphenol A-type epoxy resin and bisphenol F-type epoxy resin) manufactured by Nippon Steel Chemical & Material Co., Ltd.; "EX-721" (glycidyl ester-type epoxy resin) manufactured by Nagase ChemteX Corporation; "EX-991L" (epoxy resin containing an alkyleneoxy skeleton and a butadiene skeleton) manufactured by Nagase ChemteX Corporation; "Celloxide 2021P" (alicyclic epoxy resin having an ester skeleton) manufactured by Daicel Corporation; "PB-3600", "JP-100", "JP-200" (epoxy resin having a butadiene structure) manufactured by Nippon Soda Co., Ltd.; "ZX1658", "ZX1658GS" (liquid 1,4-glycidylcyclohexane-type epoxy resin) manufactured by Nippon Steel Chemical & Material Co., Ltd.; "EG-280" (epoxy resin containing a fluorene structure) manufactured by Osaka Gas Chemical Co., Ltd.; "EX-201" (cyclic aliphatic glycidyl ether) manufactured by Nagase ChemteX Corporation; "850" (bisphenol A-type epoxy resin) manufactured by DIC Corporation, etc.

[0027] (A) When using a combination of a solid epoxy resin and a liquid epoxy resin as the epoxy resin, their mass ratio (solid epoxy resin: 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.

[0028] (A) The epoxy resin preferably contains an epoxy resin having a skeleton selected from a naphthalene skeleton and a biphenyl skeleton, and particularly preferably contains an epoxy resin having a naphthalene skeleton.

[0029] (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., still 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 the resin per equivalent of epoxy groups. This epoxy equivalent can be measured according to JIS K7236.

[0030] (A) The weight average molecular weight (Mw) of the epoxy resin is preferably 100 to 5,000, more preferably 250 to 3,000, and still more preferably 400 to 1,500. The weight average molecular weight of the resin can be measured as a value in terms of polystyrene by gel permeation chromatography (GPC) method.

[0031] (A) When the non-volatile components of the photosensitive resin composition are taken as 100% by mass, from the viewpoint of further improving mechanical strength and insulation reliability, the content of the epoxy resin is preferably 5% by mass or more, more preferably 10% by mass or more, still more preferably 15% by mass or more, and preferably 40% by mass or less, more preferably 35% by mass or less, and still more preferably 30% by mass or less.

[0032] <(B) Resin containing a carboxy group and an ethylenic double bond> The photosensitive resin composition of the present invention contains, as component (B), a resin containing a carboxy group and an ethylenic double bond, and component (B) contains the same skeleton as component (A). The resin containing a carboxy group and an ethylenic double bond as component (B) does not include those corresponding to the above-described component (A). Component (B) may be used alone or in combination of two or more. The same skeleton means that it is the same including substituents, but the number of repeating units of the same skeleton possessed by component (A) and component (B) may be different.

[0033] Since component (B) contains the same skeleton as component (A), the compatibility between component (A) and component (B) is enhanced. As a result, the occurrence of warping is suppressed. Since the cured product of the photosensitive resin composition of the present invention has suppressed warping, when a clad layer is formed after forming a core layer using the photosensitive resin composition of the present invention, the occurrence of dimensional deviation can be suppressed, and an optical waveguide with low optical transmission loss can be manufactured. Further, since component (B) contains the same structure as component (A), fine wiring formation becomes possible.

[0034] As described above, it is preferable that the (A) epoxy resin includes an epoxy resin containing an aromatic skeleton. Therefore, it is preferable that component (B) contains the same aromatic skeleton as component (A). The details of the aromatic skeleton are as described above. As the aromatic skeleton, a polycyclic aromatic skeleton including a condensed ring is preferable, and an aromatic skeleton containing a naphthalene skeleton is more preferable. Examples of the aromatic skeleton containing a naphthalene skeleton include a naphthol novolak skeleton, a naphthalene skeleton, a naphthol skeleton, a naphthylene ether skeleton, and the like.

[0035] (B) component preferably contains the same skeleton as (A) component as a repeating unit. From the viewpoint of significantly obtaining the effects of the present invention, the same skeleton as (A) component contained in (B) component is preferably 5% or more, more preferably 10% or more, still more preferably 15% or more, and preferably 80% or less, more preferably 75% or less, still more preferably 70% or less, based on the total mass of one molecule of (B) component. The ratio of the same skeleton as (A) component to the total mass of one molecule of (B) component can be measured, for example, by NMR (Nuclear Magnetic Resonance) method.

[0036] (B) resin containing a carboxy group and an ethylenic double bond contains a carboxy group which is an acidic group. Therefore, the photosensitive resin composition of the present invention can show solubility in an alkaline developer such as an aqueous sodium carbonate solution of 1 mass%. In the (B) resin containing a carboxy group and an ethylenic double bond, the number of carboxy groups in one molecule may be 1 or 2 or more.

[0037] (B) resin containing a carboxy group and an ethylenic double bond contains an ethylenic double bond as an aliphatic carbon-carbon unsaturated bond. Therefore, the (B) resin containing a carboxy group and an ethylenic double bond can undergo polymerization when a radical is generated by the photoinitiator receiving light.

[0038] (B) resin containing a carboxy group and an ethylenic double bond usually has a group containing the above-mentioned ethylenic double bond. Since this group generally has radical polymerizability, it may be hereinafter referred to as a "radical polymerizable group". Examples of the radical polymerizable group include (meth)acryloyl group (acryloyl group or methacryloyl group), vinyl group, allyl group, propargyl group, butenyl group, ethynyl group, phenylethynyl group, maleimide group, nadimide group, etc. From the viewpoint of the reactivity of radical polymerization, the (meth)acryloyl group is preferred.

[0039] (B) The number of radically polymerizable groups per molecule of the resin containing a carboxy group and an ethylenic double bond may be 1 or may be 2 or more.

[0040] (B) In one embodiment, the resin containing a carboxy group and an ethylenic double bond is preferably an acid-modified epoxy (meth)acrylate resin.

[0041] Since the acid-modified epoxy (meth)acrylate resin has a (meth)acryloyl group, 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 1 or may be 2 or more.

[0042] The acid-modified epoxy (meth)acrylate resin preferably has both a (meth)acryloyl group and a carboxyl group, and is a resin that enables photoradical polymerization and alkali development.

[0043] The acid-modified epoxy (meth)acrylate resin can be produced by acid-modifying an epoxy (meth)acrylate resin by a known method. The epoxy (meth)acrylate resin can be produced, for example, by reacting an epoxy resin with acrylic acid or methacrylic acid.

[0044] As the epoxy resin for the production of the epoxy (meth)acrylate resin, it is a compound having an epoxy group in the molecule and is not particularly limited as long as it has the same skeleton as the component (A).Examples of epoxy resins for the production of epoxy (meth) acrylate resins include bisphenol A type epoxy resins, hydrogenated bisphenol A type epoxy resins, bisphenol F type epoxy resins, hydrogenated bisphenol F type epoxy resins, bisphenol S type epoxy resins, modified bisphenol F type epoxy resins obtained by reacting bisphenol F type epoxy resins with epichlorohydrin to modify them to trifunctional or higher, etc., bisphenol type epoxy resins; biphenol type epoxy resins such as tetramethylbiphenol type; novolak type epoxy resins such as phenol novolak type epoxy resins, cresol novolak type epoxy resins, bisphenol A type novolak type epoxy resins, alkylphenol novolak type epoxy resins; fluorine-containing epoxy resins such as bisphenol AF type epoxy resins and perfluoroalkyl type epoxy resins; naphthalene type epoxy resins, dihydroxynaphthalene type epoxy resins, polyhydroxybinaphthalene type epoxy resins, naphthol type epoxy resins, naphthol aralkyl type epoxy resins, binaphthol type epoxy resins, naphthylene ether type epoxy resins, naphthol novolak type epoxy resins, naphthalene type epoxy resins obtained by the condensation reaction of polyhydroxynaphthalene and aldehydes, etc., epoxy resins having a naphthalene structure (naphthalene structure-containing epoxy resins); bixylenol type epoxy resins; dicyclopentadiene type epoxy resins; tris-phenol type epoxy resins; tert-butyl-catechol type epoxy resins; epoxy resins containing a condensed ring skeleton such as anthracene type epoxy resins; glycidylamine type 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; spiro ring-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 acrylate esters; fluorene type epoxy resins; halogenated epoxy resins, etc.Among them, as the epoxy resin for producing the epoxy (meth)acrylate resin, either a naphthalene-type epoxy resin or a naphthol aralkyl-type epoxy resin is preferable, and a naphthalene-type epoxy resin is more preferable.

[0045] In one embodiment, the acid-modified epoxy (meth)acrylate resin preferably contains an acid-modified epoxy (meth)acrylate resin having a skeleton selected from a naphthol aralkyl skeleton, a naphthalene skeleton, and a biphenyl skeleton, and particularly preferably contains an acid-modified epoxy (meth)acrylate resin having a naphthalene skeleton.

[0046] In one embodiment, the acid-modified epoxy (meth)acrylate resin preferably contains a resin selected from an acid-modified epoxy (meth)acrylate resin in which the hydroxyl group of the epoxy (meth)acrylate resin is 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 group of the epoxy (meth)acrylate resin is urethanized (hereinafter referred to as "urethane-type acid-modified epoxy (meth)acrylate resin"), and particularly preferably contains an ester-type acid-modified epoxy (meth)acrylate resin.

[0047] The ester-type acid-modified epoxy (meth)acrylate resin can be produced, for example, by reacting an epoxy (meth)acrylate resin with a polycarboxylic acid anhydride. The ester-type acid-modified epoxy (meth)acrylate resin may be used alone or in combination of two or more.

[0048] Examples of the polycarboxylic acid anhydride include maleic anhydride, succinic anhydride, itaconic anhydride, phthalic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, trimellitic anhydride, pyromellitic anhydride, benzophenone tetracarboxylic acid dianhydride, etc. These may be used alone or in combination of two or more. Among them, succinic anhydride and tetrahydrophthalic anhydride are preferable, and tetrahydrophthalic anhydride is more preferable.

[0049] The ester-type acid-modified epoxy (meth)acrylate resin only needs to have the same skeleton as the component (A). For example, it preferably includes resins selected from cresol novolak skeleton-containing ester-type acid-modified epoxy (meth)acrylate resins, bisphenol A skeleton-containing ester-type acid-modified epoxy (meth)acrylate resins, bisphenol F skeleton-containing ester-type acid-modified epoxy (meth)acrylate resins, biphenyl skeleton-containing acid ester-type modified epoxy (meth)acrylate resins, naphthalene skeleton-containing ester-type acid-modified epoxy (meth)acrylate resins, and naphthol aralkyl skeleton-containing ester-type acid-modified epoxy (meth)acrylate resins. More preferably, it includes resins selected from naphthalene skeleton-containing ester-type acid-modified epoxy (meth)acrylate resins and naphthol aralkyl skeleton-containing ester-type acid-modified epoxy (meth)acrylate resins.

[0050] The ester-type acid-modified epoxy (meth)acrylate resin can be synthesized by known methods, or commercial products can also be used. Specific examples of commercial products include "CCR-1373H" (cresol novolak 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 novolak skeleton-containing acid-modified epoxy acrylate resin), "ZCR-1797H" (biphenyl skeleton-containing acid-modified epoxy acrylate resin) manufactured by Nippon Kayaku Co., Ltd.; "ZAR-2000" (bisphenol A skeleton-containing acid-modified epoxy acrylate resin), "ZFR-1491H", "ZFR-1533H" (bisphenol F skeleton-containing acid-modified epoxy acrylate resin) manufactured by Nippon Kayaku Co., Ltd.; "PR-300CP" (cresol novolak type acid-modified epoxy acrylate resin) manufactured by Showa Denko KK; "CCR-1179" (cresol novolak skeleton-containing epoxy acrylate resin) manufactured by Nippon Kayaku Co., Ltd., etc.

[0051] The urethane-type acid-modified epoxy (meth)acrylate resin can be produced, for example, by reacting an epoxy (meth)acrylate resin with a diisocyanate compound and a carboxy group-containing diol compound. The urethane-type acid-modified epoxy (meth)acrylate resin may be used alone or in combination of two or more kinds.

[0052] Examples of the diisocyanate compound include aromatic diisocyanate compounds such as phenylenediisocyanate, tolylene diisocyanate, xylylene diisocyanate, tetramethylxylylene diisocyanate, diphenyldiisocyanate, naphthalene diisocyanate; aliphatic diisocyanate compounds such as hexamethylene diisocyanate, dicyclohexylmethane diisocyanate, isophorone diisocyanate, arylene sulfone ether diisocyanate, allyl cyanide diisocyanate, N-acyl diisocyanate, trimethylhexamethylene diisocyanate, 1,3-bis(isocyanatomethyl)cyclohexane.

[0053] Examples of the carboxy group-containing diol compound include dimethylolpropionic acid, dimethylolbutanoic acid, dimethylolnonanoic acid and the like.

[0054] The urethane type acid-modified epoxy (meth)acrylate resin only needs to have the same skeleton as the component (A). For example, it preferably includes resins selected from cresol novolak 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, naphthalene skeleton-containing urethane type acid-modified epoxy (meth)acrylate resin, and naphthol aralkyl skeleton-containing urethane type acid-modified epoxy (meth)acrylate resin. More preferably, it includes resins selected from naphthalene skeleton-containing urethane type acid-modified epoxy (meth)acrylate resin and naphthol aralkyl skeleton-containing urethane type acid-modified epoxy (meth)acrylate resin.

[0055] The urethane type acid-modified epoxy (meth)acrylate resin 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 JP-A-2016-199719. Specific examples of commercially available products include "UXE-3024", "UXE-3011", "UXE-3012", "UXE-3024", etc. manufactured by Nippon Kayaku Co., Ltd.

[0056] From the viewpoint of improving the alkali developability of the photosensitive resin composition, the acid value of the component (B) is preferably 0.1 mgKOH / g or more, more preferably 0.5 mgKOH / g or more, still more preferably 1 mgKOH / g or more, 10 mgKOH / g or more, even more preferably 20 mgKOH / g or more, 30 mgKOH / g or more, particularly preferably 40 mgKOH / g or more, 50 mgKOH / g or more. The upper limit of the acid value of the component (B) is preferably 200 mgKOH / g or less, more preferably 150 mgKOH / g or less, still more preferably 120 mgKOH / g or less, particularly preferably 100 mgKOH / g or less.

[0057] The weight average molecular weight of component (B) is preferably 20,000 or less, more preferably 17,000 or less, still more preferably 15,000 or less, and preferably 1,000 or more, more preferably 1,500 or more. The weight average molecular weight is the weight average molecular weight in terms of polystyrene measured by gel permeation chromatography (GPC).

[0058] When the non-volatile components of the photosensitive resin composition are 100% by mass, the content of component (B) is preferably 15% by mass or more, more preferably 25% by mass or more, preferably 55% by mass or less, more preferably 65% by mass or less, still more preferably 60% by mass or less, and particularly preferably 55% by mass or less, from the viewpoint of improving alkali developability.

[0059] The mass ratio of component (B) to component (A) ((B) component / (A) component) is preferably 0.1 or more, more preferably 0.5 or more, and still more preferably 1 or more. The upper limit is preferably 10 or less, more preferably 5 or less, and still more preferably 3 or less.

[0060] <(C) Photoinitiator> The photosensitive resin composition of the present invention contains a (C) photoinitiator as component (C). The (C) photoinitiator as this (C) component does not include those corresponding to the above-described (A) component and (B) component. Component (C) may be used alone or in combination of two or more.

[0061] As component (C), a photoinitiator capable of efficiently photocuring the photosensitive resin composition can be used. Such a photoinitiator preferably includes either (C1) a photoinitiator having a molecular weight of 420 or more or (C2) a photoinitiator having a molecular weight of less than 420. As component (C), from the viewpoint of significantly obtaining the effects of the present invention, it is preferable to include either (C1) component or (C2) component, and more preferably to include (C1) component.

[0062] -(C1) A photoinitiator with a molecular weight of 420 or more (Component (C1) has a large molecular weight of 420 or more, so it is more likely to receive light during exposure than a photoinitiator with a molecular weight less than 420, and the progress rate of photopolymerization becomes faster than that of a photoinitiator with a small molecular weight. As a result, since photopolymerization proceeds before being inhibited by oxygen, the photocuring of the photosensitive resin composition can proceed rapidly, or the solubility in an alkaline developer can be rapidly decreased, enabling the formation of fine wiring. Furthermore, since it is possible to suppress the occurrence of variations in the degree of insolubilization at the surface portion of the core layer due to the influence of oxygen inhibition, it becomes possible to manufacture an optical waveguide with low optical transmission loss.)

[0063] (Regarding the molecular weight of component (C1), from the viewpoint of forming fine wiring and manufacturing an optical waveguide with low optical transmission loss, it is 420 or more, preferably 500 or more, more preferably 600 or more, and 700 or more. The upper limit is not particularly limited, but preferably 3000 or less, more preferably 2500 or less, and even more preferably 2000 or less.)

[0064] (As component (C1), a compound having a molecular weight of 420 or more, having a group that absorbs active light such as ultraviolet rays, and capable of efficiently promoting photopolymerization can be used. As such a component (C1), for example, a compound containing a structural unit represented by formula (C-1) is preferably used.)

Chemical formula

[0065] R 1represents an active ray absorbing group. The active ray absorbing group is a group capable of absorbing active rays such as ultraviolet rays. The active ray absorbing group may be any functional group capable of absorbing active rays. For example, a group having an aminoketone skeleton, a group having an anthraquinone skeleton, a group having a thioxanthone skeleton, a group having a ketal skeleton, a group having a benzophenone skeleton, a group having a xanthone skeleton, a group having an acetophenone skeleton, a group having a benzoin skeleton, a group having a thioxanthone skeleton, a group having a benzoate skeleton, and the like can be mentioned.

[0066] Specific examples of the active ray absorbing group include the following groups (i) to (vii). Among them, as the active ray absorbing group, either (i) or (ii) is preferable. In the formula, * represents a bond.

Chemical formula

[0067] R 2 each independently represents a divalent hydrocarbon group. Examples of the divalent hydrocarbon group include a divalent aliphatic hydrocarbon group and a divalent aromatic hydrocarbon group. From the viewpoint of significantly obtaining the effects of the present invention, a divalent aliphatic hydrocarbon group is preferable.

[0068] As the divalent aliphatic hydrocarbon group, a divalent saturated aliphatic hydrocarbon group is preferred, and examples thereof include an alkylene group and an alkenylene group, with an alkylene group being more preferred. The alkylene group may be linear, branched, or cyclic, with a linear structure 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, and 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, etc., and a methylene group is preferred. The alkenylene group may be linear, branched, or cyclic, with a linear structure being preferred. As 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.

[0069] Examples of the divalent aromatic hydrocarbon group include an arylene group and a heteroarylene group. As the arylene group and the heteroarylene group, an arylene group or a heteroarylene group having 6 to 20 carbon atoms is preferred, and an arylene group or a heteroarylene group having 6 to 10 carbon atoms is more preferred.

[0070] The divalent hydrocarbon group may have a substituent. Examples of the substituent include a halogen atom, an alkyl group, an alkoxy group, an aryl group, an arylalkyl group, a silyl group, an acyl group, an acyloxy group, a carboxy group, a sulfo group, a cyano group, a nitro group, a hydroxy group, a mercapto group, an oxo group, etc.

[0071] n represents an integer from 1 to 10, preferably represents an integer from 1 to 8, more preferably represents an integer from 1 to 5, and even more preferably represents an integer from 1 to 3.

[0072] The 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).

Chemical formula

[0073] R 11 each independently represents an active ray absorbing group, and is the same as the active ray absorbing group represented by R 1 in formula (C-1).

[0074] 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).

[0075] R 13 represents an m-valent hydrocarbon group. Examples of the m-valent hydrocarbon group include an m-valent aliphatic hydrocarbon group and an m-valent aromatic hydrocarbon group, and an m-valent aliphatic hydrocarbon group 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]

[0076] n1 represents an integer from 1 to 10, and is the same as n in formula (C-1).

[0077] m represents an integer from 1 to 4, an integer from 1 to 3 is preferred, and 3 is more preferred.

[0078] R 21 and R23 each independently represents an active ray absorbing group, and R in formula (C-1) 1 is the same as the active ray absorbing group represented by

[0079] R 22 each independently represents a divalent hydrocarbon group, and R in formula (C-1) 2 is the same as the divalent hydrocarbon group represented by

[0080] Specific examples of the component (C1) include the following compounds. However, the component (C1) is not limited to these specific examples. a, b, c, and d each represent an integer from 1 to 10.

Chemical formula

[0081] As the component (C1), commercially available products can be used. Examples of commercially available products include "Omnipol 910", "Omnipol TP", "Omnipol 9210", etc. manufactured by IGM.

[0082] Regarding the content of the component (C1), from the viewpoint of significantly obtaining the effects of the present invention, when the non-volatile components of the photosensitive resin composition are 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.

[0083] Regarding the mass ratio of the component (C1) to the (A) epoxy resin ((C1) component / (A) component), from the viewpoint of significantly obtaining the effects of the present invention, it is preferably 0.01 or more, more preferably 0.05 or more, and even more preferably 0.1 or more. The upper limit is preferably 5 or less, more preferably 1 or less, and even more preferably 0.5 or less.

[0084] (B) The mass ratio of component (C1) to the resin containing a carboxy group and an ethylenic double bond ((C1) component / (B) component) is preferably 0.01 or more, more preferably 0.05 or more, and even more preferably 0.1 or more from the viewpoint of significantly obtaining the effects of the present invention. The upper limit is preferably 5 or less, more preferably 1 or less, and even more preferably 0.5 or less.

[0085] -(C2) A photoinitiator having 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.

[0086] Examples of component (C2) include oxime ester-based photoinitiators, α-amino ketone-based photoinitiators, phosphine oxide-based photoinitiators, α-hydroxy ketone-based photoinitiators, benzoin-based photoinitiators, benzyl ketal-based photoinitiators, acylphosphine-based photoinitiators, and the like.

[0087] Examples of the oxime ester-based photoinitiator include 2-(benzoyloxyimino)-1-[4-(phenylthio)phenyl]octan-1-one (OXE01), [1-[9-ethyl-6-(2-methylbenzoyl)carbazol-3-yl]ethylideneamino]acetate (OXE02), ethanone, 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazol-3-yl]-, 1-(O-acetoxyoxime), and the like.

[0088] Examples of α - amino ketone - based photoinitiators 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, 2 - methyl - 1 - (9,9 - dibutylfluoren - 2 - yl) - 2 - morpholinopropan - 1 - one, and the like.

[0089] Examples of phosphine oxide - based photoinitiators include bis(2,4,6 - trimethylbenzoyl)phenylphosphine oxide, (2,4,6 - trimethylbenzoyl)diphenylphosphine oxide, polyoxyethylene glycerin ether tris[phenyl(2,4,6 - trimethylbenzoyl)phosphinate] (Polymeric TPO - L), and the like.

[0090] Examples of α - hydroxy ketone - based photoinitiators include 1 - hydroxycyclohexyl phenyl ketone, 2 - hydroxy - 2 - methyl - 1 - phenylpropanone, 1 - [4 - (2 - hydroxyethoxy)phenyl] - 2 - hydroxy - 2 - methylpropanone, 2 - hydroxy - 1 - {4 - [4 - (2 - hydroxy - 2 - methylpropionyl)benzyl]phenyl} - 2 - methylpropane - 1 - one, and the like.

[0091] Examples of benzoin - based photoinitiators include benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether, and the like. Examples of benzyl ketal - based photoinitiators include 2,2 - dimethoxy - 2 - phenylacetophenone, and the like. Examples of the acylphosphine-based photopolymerization initiator include bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide and the like.

[0092] (C2) component, in one embodiment, from the viewpoint of significantly obtaining the effects of the present invention, preferably contains any one of an oxime ester-based photopolymerization initiator, an α-amino ketone-based photopolymerization initiator, and an acylphosphine-based photopolymerization initiator.

[0093] (C2) component can use commercially available products. Specific examples of commercially available products of component (D) include "Omnirad907", "Omnirad369", "Omnirad379", "Omnirad379EG", "Omnirad819", "OmniradTPO" manufactured by IGM, "IrgacureTPO", "IrgacureOXE-01", "IrgacureOXE-02" manufactured by BASF, "N-1919" manufactured by ADEKA, and the like.

[0094] (C2) component content, from the viewpoint of significantly obtaining the effects of the present invention, is preferably 0.001% by mass or more, more preferably 0.005% by mass or more, still more preferably 0.01% by mass or more, and preferably 2% by mass or less, more preferably 1.5% by mass or less.

[0095] (C) component content ((C1) component and (C2) component total content), from the viewpoint of significantly obtaining the effects of the present invention, when the non-volatile components of the photosensitive resin composition are 100% by mass, is preferably 0.5% by mass or more, more preferably 1% by mass or more, and preferably 15% by mass or less, more preferably 13% by mass or less, still more preferably 10% by mass or less.

[0096] The photosensitive resin composition may contain, in combination with the component (C), as a photo-polymerization initiation aid, tertiary amines such as ethyl N,N-dimethylaminobenzoate, isoamyl N,N-dimethylaminobenzoate, pentyl 4-dimethylaminobenzoate, triethylamine, and triethanolamine. The photo-polymerization initiation aid may be used alone as one kind, or two or more kinds may be used in combination.

[0097] <(D) Photosensitizer> The photosensitive resin composition of the present invention may contain, as an optional component, a (D) photosensitizer. The (D) photosensitizer as the component (D) does not include those corresponding to the above-described components (A) to (C). By containing the (D) photosensitizer, the photocurability can be improved. The component (D) may be used alone as one kind, or two or more kinds may be used in combination.

[0098] The maximum value of the absorption wavelength of the (D) photosensitizer is preferably from 300 nm to 450 nm, more preferably from 330 nm to 420 nm, and particularly preferably from 350 nm to 400 nm.

[0099] The lowest excited triplet energy level of the (D) photosensitizer is preferably from 60 kcal / mol to 70 kcal / mol, more preferably from 60 kcal / mol to 65 kcal / mol, and particularly preferably from 60 kcal / mol to 63 kcal / mol.

[0100] Specific examples of the (D) photosensitizer include benzophenones, thioxanthones, thioxanthenes, anthraquinones, and the like. The (D) photosensitizer preferably contains a photosensitizer selected from benzophenones and thioxanthones.

[0101] Examples of benzophenones include benzophenone, 4-phenylbenzophenone, 4-phenoxybenzophenone, 4,4'-bis(dimethylamino)benzophenone, 4,4'-bis(diethylamino)benzophenone, methyl o-benzoylbenzoate, 4-methylbenzophenone, and the like.

[0102] Examples of thioxanthones include 2,4-diethylthioxanthen-9-one, 2-isopropylthioxanthen-9-one, 1-isopropylthioxanthen-9-one, 2,4-diisopropylthioxanthen-9-one, and the like.

[0103] Examples of thioxanthenes include thioxanthene, 2-chlorothioxanthene, 2,4-diethylthioxanthene, (2-carboxymethoxythioxanthone)-(polytetramethylene glycol 250) diester, and the like.

[0104] Examples of anthraquinones include 2-ethylanthraquinone, 1-chloroanthraquinone, 2,3-diphenylanthraquinone, and the like.

[0105] As the component (D), commercially available products can be used. Specific examples of commercially available products of the component (D) include "DETX-S" manufactured by Nippon Kayaku Co., Ltd., "EAB" manufactured by Tokyo Chemical Industry Co., Ltd., "OmipolTX" ((2-carboxymethoxythioxanthone)-(polytetramethylene glycol 250) diester) manufactured by IGM, and the like.

[0106] When the non-volatile components of the photosensitive resin composition are 100% by mass, the content of the component (D) photosensitizer is preferably 0.0001% by mass or more, more preferably 0.0005% by mass or more, still more preferably 0.001% by mass or more, from the viewpoint of further improving photocurability. The upper limit is preferably 5% by mass or less, more preferably 3% by mass or less, still more preferably 2% by mass or less, and particularly preferably 1.5% by mass or less.

[0107] <(E) Inorganic filler with an average particle size of 100 nm or less> The photosensitive resin composition of the present invention may contain, as an optional component, (E) an inorganic filler having an average particle size of 100 nm or less. The (E) inorganic filler is contained in the resin composition in a particulate state.

[0108] From the viewpoint of suppressing light reflection during exposure and obtaining excellent core formability (resolution), the average particle size of the (E) component 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.

[0109] The average particle size of the inorganic filler can be measured by the laser diffraction / scattering method based on the Mie scattering theory. Specifically, it can be measured by creating a volume-based particle size distribution of the inorganic filler using a laser diffraction / scattering type particle size distribution measuring device and taking the median diameter as the average particle size. As the measurement sample, a dispersion of the inorganic filler in water by ultrasonic waves can preferably be used. As the laser diffraction / scattering type particle size distribution measuring device, "LA-500" manufactured by Horiba, Ltd., "SALD-2200" manufactured by Shimadzu Corporation, etc. can be used.

[0110] (E) From the viewpoint of suppressing light reflection during exposure and obtaining excellent core formability (resolution), the specific surface area of the component is preferably 1 m 2 / g or more, more preferably 3 m 2 / g or more, particularly preferably 5 m 2 / g or more. There is no particular upper limit, but preferably 60 m 2 / g or less, 50 m 2 / g or less or 40 m 2 / g or less. The specific surface area can be obtained by adsorbing nitrogen gas on the sample surface using a specific surface area measuring device (Macsorb HM-1210 manufactured by Mountech Co., Ltd.) according to the BET method and calculating the specific surface area using the BET multipoint method.

[0111] As the material of the (E) component, an inorganic compound is used. Examples of the material of the (E) component 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 the silica. The (E) component may be used alone or in combination of two or more in any ratio.

[0112] Commercially available products can be used as the (E) component. Examples of such commercially available products include "Adma Nano Series" manufactured by Admatechs Co., Ltd. such as Y50SZ-AM1, "UFP Series" manufactured by Denki Kagaku Kogyo Co., Ltd., "Sciqas Series" manufactured by Sakai Chemical Industry Co., Ltd., "Sea Hostar Series" manufactured by Nippon Shokubai Co., Ltd., and "BF Series" manufactured by Sakai Chemical Industry Co., Ltd.

[0113] From the viewpoint of enhancing moisture resistance and dispersibility, the (E) component is preferably treated with a surface treatment agent. Examples of the surface treatment agent include fluorine-containing silane coupling agents, aminosilane-based coupling agents, epoxysilane-based coupling agents, mercaptosilane-based coupling agents, silane-based coupling agents, alkoxysilane, organosilazane compounds, and titanate-based coupling agents. The surface treatment agent may be used alone or in any combination of two or more.

[0114] Examples of commercially available surface treatment agents include, for example, "KBM403" (3-glycidoxypropyltrimethoxysilane) manufactured by Shin-Etsu Chemical Co., Ltd., "KBM803" (3-mercaptopropyltrimethoxysilane) manufactured by Shin-Etsu Chemical Co., Ltd., "KBE903" (3-aminopropyltriethoxysilane) manufactured by Shin-Etsu Chemical Co., Ltd., "KBM573" (N-phenyl-3-aminopropyltrimethoxysilane) manufactured by Shin-Etsu Chemical Co., Ltd., "SZ-31" (hexamethyldisilazane) manufactured by Shin-Etsu Chemical Co., Ltd., "KBM103" (phenyltrimethoxysilane) manufactured by Shin-Etsu Chemical Co., Ltd., "KBM-4803" (long-chain epoxy type silane coupling agent) manufactured by Shin-Etsu Chemical Co., Ltd., "KBM-7103" (3,3,3-trifluoropropyltrimethoxysilane) manufactured by Shin-Etsu Chemical Co., Ltd., and the like.

[0115] From the viewpoint of improving the dispersibility of the inorganic filler, the degree of surface treatment with the surface treatment agent preferably falls 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 surface-treated with 0.2% to 3% by mass, and even more preferably surface-treated with 0.3% to 2% by mass.

[0116] The degree of surface treatment with the 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 is preferably 0.02 mg / m 2 or more, more preferably 0.1 mg / m 2 or more, and even more preferably 0.2 mg / m 2 or more. On the other hand, from the viewpoint of preventing an increase in the melt viscosity of the resin composition and the melt viscosity in the sheet form, it is preferably 1.0 mg / m 2 or less, more preferably 0.8 mg / m 2 or less, and even more preferably 0.5 mg / m 2 or less.

[0117] (E) The amount of carbon per unit surface area can be measured after the surface-treated inorganic filler is washed with a solvent (e.g., methyl ethyl ketone (MEK)). Specifically, a sufficient amount of MEK as a solvent is added to the inorganic filler 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 solid content, the amount of carbon per unit surface area of the inorganic filler can be measured using a carbon analyzer. As the carbon analyzer, "EMIA-320V" manufactured by Horiba, Ltd. can be used.

[0118] (E) When the non-volatile components in the photosensitive resin composition are 100% by mass, the content of component (E) is preferably 5% by mass or more, more preferably 10% by mass or more, still more preferably 15% by mass or more, preferably 35% by mass or less, more preferably 30% by mass or less, and still more preferably 25% by mass or less from the viewpoint of significantly obtaining the effects of the present invention.

[0119] <(F) Reactive diluent> The photosensitive resin composition of the present invention may contain (F) a reactive diluent as an optional component. The (F) reactive diluent as this (F) component does not include those corresponding to the above-described (A) to (E) components. The (F) component may be used alone or in combination of two or more.

[0120] (F) By including a reactive diluent in the photosensitive resin composition, the photoreactivity can be improved. As the (F) 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.

[0121] Typical (meth)acrylate compounds include, for example, hydroxyalkyl acrylates such as 2-hydroxyethyl acrylate and 2-hydroxybutyl acrylate; mono- or di-acrylates 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 alcohols such as trimethylolpropane, pentaerythritol, and dipentaerythritol, or polyhydric acrylates of their adducts with ethylene oxide, propylene oxide, or ε-caprolactone; phenol acrylates such as phenoxyacrylate and phenoxyethyl acrylate, or acrylates of their adducts with ethylene oxide or propylene oxide; epoxy acrylates derived from glycidyl ethers such as trimethylolpropane triglycidyl ether, modified epoxy acrylates, melamine acrylates, and / or methacrylates corresponding to the above-mentioned acrylates, etc.Among these, polyvalent acrylates or polyvalent methacrylates are preferred. For example, as trivalent acrylates or methacrylates, trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, trimethylolpropane EO-added tri(meth)acrylate, glycerin PO-added tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, tetrafluorofurfuryl 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, dipentaerythritol hexa(meth)acrylate, (meth)acrylic acid ester of N,N,N',N'-tetrakis(β-hydroxyethyl)ethyldiamine, etc. can be mentioned. As acrylates or methacrylates with a valence of 3 or more, tri(2-(meth)acryloyloxyethyl) phosphate, tri(2-(meth)acryloyloxypropyl) phosphate, tri(3-(meth)acryloyloxypropyl) phosphate, tri(3-(meth)acryloyl-2-hydroxyl oxypropyl) phosphate, di(3-(meth)acryloyl-2-hydroxyl oxypropyl)(2-(meth)acryloyloxyethyl) phosphate, (3-(meth)acryloyl-2-hydroxyl oxypropyl)di(2-(meth)acryloyloxyethyl) phosphate and other phosphate triesters (meth)acrylates can be mentioned. These photosensitive (meth)acrylate compounds may be used alone or in combination of two or more. "EO" refers to ethylene oxide.

[0122] (F) As the reaction diluent, commercially available products can be used. Examples of commercially available products include "DPHA" manufactured by Nippon Kayaku Co., Ltd., "EBECRYL3708" manufactured by Daicel Ornex Co., Ltd., etc.

[0123] (F) The reactive diluent usually has a low viscosity. The specific viscosity of the (F) reactive diluent is usually less than 0.5 Pa·s. The lower limit of the viscosity of the (F) reactive diluent has no particular limitation and can be, for example, 0.001 Pa·s or more, 0.005 Pa·s or more, 0.01 Pa·s or more, etc. The viscosity of the (F) reactive diluent can be measured using an E-type viscometer at 25 ± 2°C.

[0124] As the content of the (F) reactive diluent, when the non-volatile components in the photosensitive resin composition are 100% by mass, from the viewpoint of promoting photocuring, it 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 still more preferably 25% by mass or less.

[0125] <(G) Solvent> The photosensitive resin composition may contain a (G) solvent as a volatile component in combination with the non-volatile components such as the above-described (A) to (F) components. According to the (G) solvent as the (G) component, the viscosity of the photosensitive resin composition can be adjusted. Examples of the (G) solvent include organic solvents.

[0126] (G) Examples of the solvent 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 solvents such as petroleum ether, petroleum naphtha, hydrogenated petroleum naphtha, and solvent naphtha. The (G) solvent may be used alone or in combination of two or more.

[0127] (G) From the viewpoint of the coatability of the photosensitive resin composition, it is preferable to appropriately adjust the amount of the (G) solvent.

[0128] <(H) Optional Additive> The photosensitive resin composition of the present invention may further contain (H) an optional additive as an optional component in a range that does not significantly impair the effects of the present invention in combination with the above-described components (A) to (G). The (H) optional additive does not include those corresponding to the above-described components (A) to (G). The (H) optional additive may be used alone or in combination of two or more.

[0129] Examples of the (H) optional additive include ultraviolet absorbers, silane coupling agents, plasticizers, flame retardants, antistatic agents, antioxidants, antibacterial agents, defoaming agents, leveling agents, thickeners, adhesion promoters, thixotropic agents, release agents, surface treatment agents, dispersants, surface modifiers, stabilizers, and the like.

[0130] The photosensitive resin composition can be produced as a resin varnish by mixing the above components (A) to (C) as essential components, appropriately mixing the above components (D) to (H) as optional components, and kneading or stirring, as necessary, by means of kneading such as a three-roll mill, ball mill, bead mill, sand mill, etc., or stirring means such as a super mixer, planetary mixer, high-speed rotary mixer, etc.

[0131] <Physical properties and uses of the photosensitive resin composition> Since the photosensitive resin composition contains the components (A) to (C) in combination, it exhibits the characteristic that the occurrence of warpage is suppressed. Specifically, the photosensitive resin composition is exposed and developed, and then the photosensitive resin composition is cured to obtain a cured product. The cured product is placed on a horizontal table while fixing one long side of the cured product. The height of the other long side from the table (the warpage amount in the short side direction) is measured. At this time, the warpage amount is preferably less than 10 mm, more preferably less than 5 mm. The lower limit is not particularly limited, but can be 0 mm or more, 0.1 mm or more, etc. The warpage amount can be measured according to the method described in the examples below.

[0132] Since the photosensitive resin composition contains the components (A) to (C) in combination, it usually exhibits the characteristic that the optical transmission loss can be reduced. Specifically, a test substrate having a core layer formed using a clad layer and the photosensitive resin composition is produced. 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 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.

[0133] Since the photosensitive resin composition contains components (A) to (C) in combination, it usually exhibits the property of being excellent in core formation. Specifically, when the photosensitive resin composition is exposed and developed to form a line layer, a line layer with a small minimum fine formation width can be formed. For example, 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. In this case, in any of the line layers, the aspect ratio of the line layer can be preferably 0.6 or more, more preferably 1 or more. Here, in L / S, L (line) represents the width of the line layer, and S (space) represents the interval between the lines. Also, the aspect ratio of the line layer represents the ratio expressed as "layer thickness / line width" of the line layer. According to the resin composition having such excellent core formation properties, a core layer with a small width and interval can be formed, and miniaturization of the optical waveguide can be achieved. The measurement of the minimum fine formation width can be performed according to the method described in the examples below.

[0134] Since the photosensitive resin composition contains components (A) to (C) in combination, it usually exhibits the property of obtaining a cured product with a low average linear thermal expansion coefficient (CTE). Specifically, the photosensitive resin composition is cured to obtain a cured product. Using a thermomechanical analyzer, the CTE of the cured product from 25°C to 150°C is measured. At this time, the CTE is preferably 100 ppm or less, more preferably less than 80 ppm. The lower limit is not particularly limited, but can be 0.1 ppm or more, etc. The average linear thermal expansion coefficient (CTE) can be measured according to the method described in the examples below.

[0135] Since the photosensitive resin composition contains components (A) to (C) in combination, it exhibits the property of obtaining 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 can be 0.0001 or more, etc. The absorbance can be measured according to the method described in the examples below.

[0136] The photosensitive resin composition of the present invention can usually remove the unexposed portion that has not been irradiated with light with a developer. In particular, the photosensitive resin composition of the present invention can be well removed with sodium carbonate as an alkaline developer. Therefore, the photosensitive resin composition of the present invention can be suitably used for sodium carbonate development.

[0137] In addition, the photosensitive resin composition of the present invention is excellent in core formation properties and can reduce optical transmission loss, so it can be suitably used 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 (a photosensitive resin composition for forming the core layer of an optical waveguide), and for forming an optical waveguide capable of transmitting light with a wavelength of 1300 nm to 1320 nm (a photosensitive resin composition for the use of forming an optical waveguide capable of transmitting light with a wavelength 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, it is preferably used for forming a single-mode optical waveguide for light with a wavelength of 1310 nm.

[0138] [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 of the photosensitive resin composition of the present invention provided on the support.

[0139] Examples of the support include polyethylene terephthalate film, polyethylene naphthalate film, polypropylene film, polyethylene film, polyvinyl alcohol film, triacetyl acetate film, etc., and polyethylene terephthalate film is particularly preferred.

[0140] Examples of commercially available supports include polypropylene films such as the product names "Alfan MA-410" and "E-200C" manufactured by Oji Paper Co., Ltd., and those manufactured by Shin-Etsu Film Co., Ltd., and polyethylene terephthalate films such as the PS series with the product name "PS-25" manufactured by Teijin Limited, etc., but are not limited thereto. In order to facilitate the removal of the photosensitive resin composition layer, it is preferable that a release agent such as a silicone coating agent is applied to the surface. 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. By setting the thickness to 5 μm or more, it is possible to suppress the support from being torn during the support peeling performed before development, and by setting the thickness to 50 μm or less, it is possible to improve the resolution when exposing from above the support. Also, a support with low fish-eye is preferred. Here, fish-eye refers to a situation where foreign substances, undissolved substances, oxidation degradation products, etc. of the material are incorporated into the film when the film is manufactured by methods such as heat melting, kneading, extrusion, biaxial stretching, and casting of the material.

[0141] Also, in order to reduce the light scattering during exposure with actinic rays such as ultraviolet rays, the support is preferably one with excellent transparency. Specifically, the support preferably has a haze (haze standardized in JIS-K6714) as an index of transparency in the range of 0.1 to 5. Furthermore, the photosensitive resin composition layer may be protected with a protective film.

[0142] By protecting the photosensitive resin composition layer side of the resin sheet with a protective film, it is possible to prevent the adhesion of dust and the like and scratches on the surface of the photosensitive resin composition layer. As the protective film, a film composed of the same material as the above-described support can be used. The thickness of the protective film is not particularly limited, but 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. By setting the thickness to 1 μm or more, the handleability of the protective film can be improved, and by setting it to 40 μm or less, the cost tends to be reduced. Note that, with respect to the adhesive force between the photosensitive resin composition layer and the support, it is preferable that the adhesive force between the photosensitive resin composition layer and the protective film is smaller.

[0143] The resin sheet can be produced, for example, by preparing a resin varnish in which the photosensitive resin composition of the present invention is dissolved in an organic solvent, applying this resin varnish onto a support, and drying the organic solvent by heating or blowing hot air or the like to form a photosensitive resin composition layer. Specifically, first, after completely removing the bubbles in the photosensitive resin composition by a vacuum degassing method or the like, the photosensitive resin composition is applied onto a support, and the solvent is removed and dried by a hot air furnace or an infrared furnace, and then, if necessary, a protective film is laminated on the obtained photosensitive resin composition layer to produce a resin sheet. Specific drying conditions vary depending on the curability of the photosensitive resin composition and the amount of the organic solvent in the resin varnish, but in the case of a resin varnish containing 30% by mass to 60% by mass of the organic solvent, it can be dried at 80°C to 120°C for 3 minutes to 13 minutes. The amount of the residual organic solvent in the photosensitive resin composition layer is preferably 5% by mass or less, more preferably 2% by mass or less, based on the total amount of the photosensitive resin composition layer, from the viewpoint of preventing the diffusion of the organic solvent in the subsequent process. A person skilled in the art can appropriately set suitable drying conditions by simple experiments.

[0144] From the perspective of improving handleability and suppressing a decrease in sensitivity and resolution inside the photosensitive resin composition layer, the thickness of the photosensitive resin composition layer is preferably 1 μm or more, more preferably 2 μm or more, still more preferably 3 μm or more, and preferably 15 μm or less, more preferably 13 μm or less, still more preferably 10 μm or less.

[0145] Examples of the coating method of the photosensitive resin composition include, for example, gravure coating method, microgravure coating method, reverse coating method, kiss reverse coating method, die coating method, slot die method, lip coating method, comma coating method, blade coating method, roll coating method, knife coating method, curtain coating method, chamber gravure coating method, slot orifice method, spray coating method, dip coating method, etc.

[0146] The photosensitive resin composition may be applied in several portions, may be applied once, or may be applied by combining a plurality of different methods. Among them, the die coating method, which is excellent in uniform coating properties, is preferable. Further, in order to avoid foreign matter mixing, etc., it is preferable to carry out the coating process in an environment with less generation of foreign matter such as a clean room.

[0147] [Photosensitive Resin Composition Set] The photosensitive resin composition of the present invention can be suitably used as a photosensitive resin composition for forming a 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 a clad. The photosensitive resin composition set can be used for manufacturing an optical waveguide including a core layer containing a cured product of the photosensitive resin composition of the present invention and a clad layer containing a cured product of the photosensitive resin composition for a clad. As the photosensitive resin composition for a clad, a known photosensitive resin composition can be used. Since both the photosensitive resin composition of the present invention and the photosensitive resin composition for a clad are photosensitive resin compositions, usually, it is possible to efficiently manufacture a fine optical waveguide by a method including exposure and development.

[0148] [Optical Waveguide] The above-described photosensitive resin composition, resin sheet, and photosensitive resin composition set can be used for manufacturing an optical waveguide. Hereinafter, embodiments of the optical waveguide will be described with reference to the drawings.

[0149] FIG. 1 is a perspective view schematically showing an optical waveguide 10 according to an embodiment of the present invention. As shown in FIG. 1, the optical waveguide 10 includes 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, and preferably contains only the cured product of the photosensitive resin composition of the present invention. The cladding layer 200 contains a cured product of a resin composition for cladding, and preferably contains only the cured product of the resin composition for cladding. As the resin composition for cladding, a resin composition capable of obtaining a cured product having a refractive index lower than that of the cured product of the photosensitive resin composition of the present invention can be used. As the resin composition for cladding, a photocurable resin composition or a thermosetting resin composition may be used.

[0150] The core layer 100 is provided in the cladding layer 200. Therefore, the core layer 100 is covered by the cladding layer 200. Usually, 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 with each other without any other layer in between, and thus an interface 100I may be formed between the core layer 100 and the cladding layer 200. Usually, 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 (the incident-side end) 100A to the other end (the emission-side end) 100B of the core layer 100.

[0151] The wavelength of light that can be transmitted by the optical waveguide 10 can be selected in various ways. For example, the preferred wavelength range of the transmitted light can be 840 nm to 860 nm (for example, 850 nm), 1300 nm to 1320 nm (for example, 1310 nm), 1540 nm to 1560 nm (for example, 1550 nm), and the like. Among them, the wavelength range of the light transmitted through the optical transmission path 10 is preferably 1300 nm to 1320 nm.

[0152] The optical waveguide 10 may be a single-mode optical waveguide or a multi-mode optical waveguide, but it is preferably a single-mode optical waveguide. Among them, the optical waveguide 10 is preferably a single-mode optical waveguide for light in the above-mentioned preferred wavelength range. For example, the optical waveguide 10 is preferably a single-mode optical waveguide for light at 1310 nm.

[0153] The width L of the core layer 100 is desirably appropriately set within a range where light transmission is possible. 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 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 as viewed from the thickness direction.

[0154] The interval S between the core layers 100 is desirably appropriately set within a range where light transmission is possible. The specific range of the interval S between 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, particularly preferably 300 μm or less. The interval S between the core layers 100 corresponds to the interval (space) between the core layers as viewed from the thickness direction.

[0155] The thickness T of the core layer 100 is desirably appropriately set within a range where light transmission is possible. 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 be 10 μm or less.

[0156] The thickness of the cladding layer 200 is usually larger than that 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, and preferably 40 μm or less, more preferably 30 μm or less, particularly preferably 20 μm or less.

[0157] The optical waveguide 10 may optionally include any elements other than the core layer 100 and the cladding layer 200. For example, the optical waveguide 10 may include a substrate 300. In the optical waveguide 10 including the substrate 300, usually, the cladding layer 200 is provided on the substrate 300, and the core layer 100 is provided in the cladding layer 200.

[0158] As the substrate 300, a hard substrate such as a glass substrate, a metal substrate, a ceramic substrate, a wafer, or a circuit board may be used. As the wafer, for example, a semiconductor wafer such as a silicon wafer, a gallium arsenide (GaAs) wafer, an indium phosphide (InP) wafer, a gallium phosphide (GaP) wafer, a gallium nitride (GaN) wafer, a gallium telluride (GaTe) wafer, a zinc selenide (ZnSe) wafer, or a silicon carbide (SiC) wafer may be used, or a dummy wafer may be used. As the dummy wafer, for example, a plate-like member including a mold resin and electronic components embedded in the mold resin can be used. Examples of the circuit board include a glass epoxy substrate, a metal substrate, a polyester substrate, a polyimide substrate, a BT resin substrate, and a thermosetting polyphenylene ether substrate. Here, the circuit board refers to a substrate having a conductor layer (circuit) formed by pattern processing on one or both sides of the above-described substrate. Further, as the substrate 300, a film formed of a plastic material such as polyethylene terephthalate, polyimide, or polyester may be used. Further, a flexible circuit board may be employed as the substrate 300.

[0159] Further, the optical waveguide 10 may include, as an optional element, a protective layer (not shown) that protects the core layer 100 and the cladding layer 200. The protective layer may be provided, for example, so as to cover the surface of the cladding layer 200 opposite to the base material 300.

[0160] As described above, the optical waveguide 10 can have a small transmission loss. Further, since the optical waveguide 10 can be formed using a core resin composition and a cladding resin composition having excellent core formability, fine patterning of the core layer is possible, and it can be formed with a small line width L as described above.

[0161] The optical waveguide 10 can be manufactured using the photosensitive resin composition of the present invention. For example, the optical waveguide 10 Step (I) of forming a first composition layer containing a resin composition for cladding; Step (II) of curing the first composition layer; Step (III) of forming a second composition layer containing the photosensitive resin composition of the present invention on the first composition layer; Step (IV) of performing an exposure treatment on the second composition layer; Step (V) of performing a development treatment on the second composition layer; Step (VI) of curing the second composition layer; Step (VII) of forming a third composition layer containing a resin composition for cladding on the second composition layer; Step (VIII) of curing the third composition layer; It can be manufactured by a method including the following steps in this order.

[0162] FIG. 2 is a schematic cross-sectional view for explaining step (I) of a method for manufacturing an optical waveguide according to an embodiment of the present invention. As shown in FIG. 2, the method for manufacturing an optical waveguide according to an 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 the base material 300 will be described.

[0163] There is no particular limitation on the method for forming the first composition layer 210. For example, the first composition layer 210 may be formed by applying a resin composition for a cladding onto a substrate 300. From the viewpoint of smooth application, a varnish-like resin composition for a cladding containing a solvent may be prepared and the varnish-like resin composition for a cladding may be applied.

[0164] Examples of the coating method include, for example, a gravure coating method, a microgravure coating method, a reverse coating method, a kiss reverse coating method, a die coating method, a slot die method, a lip coating method, a comma coating method, a blade coating method, a roll coating method, a knife coating method, a curtain coating method, a chamber gravure coating method, a slot orifice method, a spin coating method, a slit coating method, a spray coating method, a dip coating method, a hot melt coating method, a bar coating method, an applicator method, an air knife coating method, a curtain flow coating method, an offset printing method, a brush painting method, a screen printing method, and the like.

[0165] The resin composition for a cladding may be applied once or may be applied in multiple portions. Further, different coating methods may be combined and implemented. In order to avoid foreign matter contamination, it is preferable that the application is carried out in an environment with less generation of foreign matter such as a clean room.

[0166] After the application of the resin composition for a cladding, if necessary, the first composition layer 210 may be dried. The drying can be carried out by a drying device such as a hot air furnace or a far-infrared furnace. The drying conditions are preferably set appropriately according to the composition of the resin composition for a cladding. As a specific example, the drying temperature is preferably 50°C or higher, more preferably 70°C or higher, particularly preferably 80°C or higher, and preferably 150°C or lower, more preferably 130°C or lower, particularly preferably 120°C or lower. Also, the drying time is preferably 30 seconds or longer, more preferably 60 seconds or longer, particularly preferably 120 seconds or longer, and preferably 60 minutes or shorter, more preferably 20 minutes or shorter, particularly preferably 5 minutes or shorter.

[0167] The formation of the first composition layer 210 may be carried out, for example, using a clad photosensitive resin composition sheet including a clad photosensitive resin composition made of a support and a clad photosensitive resin composition. To give a specific example, the first composition layer 210 can be formed on the base material 300 by laminating the clad photosensitive resin composition layer of the clad resin sheet on the base material 300. Lamination is usually carried out by pressing the clad photosensitive resin composition layer of the resin sheet onto the base material 300 while heating. This lamination is preferably carried out under reduced pressure by the vacuum lamination method. Also, before lamination, a preheating treatment for heating the resin sheet and the base material may be carried out as necessary.

[0168] The conditions for lamination can be, for example, carried out under the conditions of a pressure bonding temperature (lamination temperature) of 70°C to 140°C, a pressure bonding pressure of 1 kgf / cm 2 ~11 kgf / cm 2 (9.8×10 4 N / m 2 ~107.9×10 4 N / m 2 ), and a pressure bonding time of 5 seconds to 300 seconds. Also, lamination is preferably carried out under reduced pressure with an air pressure of 20 mmHg (26.7 hPa) or less. Lamination may be carried out batchwise or continuously using a roll.

[0169] The vacuum lamination method can be carried out using a commercially available vacuum laminator. Examples of commercially available vacuum laminators include, for example, the Vacuum Applicator manufactured by Nikkō Materials Co., Ltd., the Vacuum Pressure Laminator manufactured by Meiki Seisakusho Co., Ltd., the Roll-Type Dry Coater manufactured by Hitachi Industries Co., Ltd., the Vacuum Laminator manufactured by Hitachi AIC Inc., and the like.

[0170] When the first composition layer 210 is formed using a clad resin sheet provided with a support, the support is usually peeled off at an appropriate time before step (III).

[0171] In step (I), the first composition layer 210 formed on the substrate 300 usually contains a resin composition for cladding, and preferably contains only the resin composition for cladding.

[0172] The method for manufacturing an optical waveguide according to an embodiment of the present invention includes step (II) of curing the first composition layer 210 after step (I). In this step (II), for example, the first composition layer 210 may be heat-treated. The heat treatment conditions may be selected according to the type and amount of the resin component in the resin composition for cladding, and preferably may be in the range of 150°C to 250°C for 20 minutes to 180 minutes, more preferably in the range of 160°C to 230°C for 30 minutes to 120 minutes. The heat treatment is preferably performed in an inert atmosphere such as a nitrogen atmosphere.

[0173] Also, the curing of the first composition layer 210 may be performed by an exposure treatment. In one example, the specific range of the exposure amount is preferably 10 mJ / cm 2 or more, more preferably 50 mJ / cm 2 or more, particularly preferably 200 mJ / cm 2 or more, and preferably 10,000 mJ / cm 2 or less, more preferably 8,000 mJ / cm 2 or less, still more preferably 4,000 mJ / cm 2 or less, particularly preferably 1,000 mJ / cm 2 or less. Also, the exposure treatment and the heat treatment may be combined to cure the first composition layer 210.

[0174] FIG. 3 is a schematic cross-sectional view for explaining step (II) of the method for manufacturing an optical waveguide according to an embodiment of the present invention. By curing the first composition layer 210 in step (II), as shown in FIG. 3, a cured first composition layer 220 is obtained on the substrate 300. This cured first composition layer 220 forms a part of the cladding layer 200, and hereinafter may be referred to as the "lower cladding layer" 220.

[0175] FIG. 4 is a schematic cross-sectional view for explaining step (III) of the method for manufacturing an optical waveguide according to an embodiment of the present invention. The method for manufacturing an optical waveguide according to an embodiment of the present invention includes, after step (II), as shown in FIG. 4, step (III) of forming a second composition layer 110 containing the photosensitive resin composition of the present invention on the lower cladding layer 220 as the cured first composition layer.

[0176] There is no particular limitation 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 performing the application smoothly, a varnish-like photosensitive resin composition containing a solvent may be prepared and the varnish-like photosensitive resin composition may be applied. The application of the photosensitive resin composition of the present invention can be performed in the same manner as the application of the resin composition for cladding. Further, after the application of the photosensitive resin composition of the present invention, the second composition layer 110 may be dried as necessary. The drying of the second composition layer 110 can adopt the same method and conditions as the drying of the first composition layer 210.

[0177] The formation of the second composition layer 110 may be performed using a resin sheet, for example. 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 performed in the same manner as the lamination of the resin sheet for cladding. Further, the support of the resin sheet is peeled off at an appropriate time before step (V).

[0178] The second composition layer 110 formed on the lower cladding layer 220 in step (III) usually contains the photosensitive resin composition of the present invention, and preferably contains only the photosensitive resin composition of the present invention.

[0179] FIG. 5 is a schematic cross-sectional view for explaining step (IV) of the method for manufacturing an optical waveguide according to an embodiment of the present invention. The method for manufacturing an optical waveguide according to an embodiment of the present invention includes, as shown in FIG. 5, step (IV) of performing an exposure treatment on the second composition layer 110 after step (III).

[0180] In step (V), a latent image is formed in the second composition layer 110 by an exposure process. Specifically, in the exposure process, light P is selectively irradiated onto specific portions of the second composition layer 110. Thus, when the exposure process is performed, the second composition layer 110 is provided with an exposed portion 111 irradiated with light and an unexposed portion 112 not irradiated with light. Usually, since the core resin composition functions as a negative-type photosensitive resin composition, a latent image corresponding to the core layer is formed by the exposed portion 111.

[0181] From the viewpoint of performing 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. Light P passes through the light-transmitting portion 410 and enters the exposed portion 111, but cannot pass through the light-shielding portion 420 and thus cannot enter the unexposed portion 112. Therefore, the exposed portion 111 and the unexposed 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 brought into close contact with the second composition layer 110 as shown in FIG. 5 (contact exposure method), or exposure may be performed using parallel light rays without bringing it into close contact (non-contact exposure method).

[0182] 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 where the core layer of the optical waveguide is absent. The "planar shape" represents the shape as viewed from the thickness direction unless otherwise specified. The light-transmitting portion 410 formed in the planar shape corresponding to the core layer may be hereinafter referred to as a "mask pattern".

[0183] As the light P used in the exposure process in step (V), it is preferable to use appropriate actinic rays according to the composition of the photosensitive resin composition of the present invention. The wavelength of the actinic rays is usually 190 nm to 1000 nm, preferably 240 nm to 550 nm, but light rays with other wavelengths may also be used. Specific examples of the actinic light source include ultraviolet rays, visible light rays, electron beams, X-rays, etc., and ultraviolet rays are particularly preferable. The exposure amount of the light P is preferably set so that a desired core layer can be formed after curing in step (VII). In one example, the specific range of the exposure amount in step (V) is preferably 10 mJ / cm 2 or more, more preferably 50 mJ / cm 2 or more, particularly preferably 200 mJ / cm 2 or more, and preferably 10,000 mJ / cm 2 or less, more preferably 8,000 mJ / cm 2 or less, even more preferably 4,000 mJ / cm 2 or less, particularly preferably 1,000 mJ / cm 2 or less.

[0184] When the second composition layer 110 is formed using the resin sheet of the present invention, in step (IV), a support (not shown) may exist on the second composition layer 110. When a support exists on the second composition layer 110, exposure may be performed through the support, or exposure may be performed after peeling off the support.

[0185] Since the photosensitive resin composition of the present invention functions as a negative-type photosensitive resin composition, the solubility in the developer decreases in the exposed portion 111. On the other hand, the solubility in the developer is high in the unexposed portion 112. Utilizing the difference in solubility between this exposed portion 111 and the unexposed portion 112, the development process in the subsequent step (VI) is performed.

[0186] In the method for manufacturing an optical waveguide according to an embodiment of the present invention, from the viewpoint of curing the second composition layer 110 after step (IV) and before step (V), a step (IX) of heating the second composition layer 110 may be included. By step (IX), the solubility of the exposed portion 111 in the developer can be rapidly decreased. The heating in step (IX) may be performed on a hot plate or in an oven. The heating temperature can be, for example, 40°C or higher and 110°C or lower. Also, the heating time can be, for example, 30 seconds or longer and 60 minutes or shorter.

[0187] FIG. 6 is a schematic cross-sectional view for explaining step (V) of the method for manufacturing an optical waveguide according to an embodiment of the present invention. The method for manufacturing an optical waveguide according to an embodiment of the present invention includes a step (V) of subjecting the second composition layer 110 to a development process after step (IV). According to the development process, the latent image formed in step (IV) can be developed. Since the photosensitive resin composition of the present invention functions as a negative photosensitive resin composition, as shown in FIG. 6, the exposed portion 111 is not removed by the development process, while the unexposed portion 112 (see FIG. 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 FIG. 5) of the mask 400 used in step (IV).

[0188] As the development method, usually, a wet development method of bringing the second composition layer 110 into contact with a developer is performed. As the developer, an alkaline aqueous solution is usually used.

[0189] Examples of the alkaline aqueous solution as the developer include aqueous solutions of alkali metal compounds. Examples of the 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; alkali metal pyrophosphates such as sodium pyrophosphate and potassium pyrophosphate, and the like. Further, examples of the alkaline aqueous solution include aqueous solutions of organic bases containing no metal ions, such as tetraalkylammonium hydroxide. The alkaline aqueous solution may be used alone or in combination of two or more. Among them, from the viewpoint of significantly obtaining the effects of the present invention, the solute of the developer is preferably an alkali metal carbonate or bicarbonate, and sodium carbonate is more preferable.

[0190] The developer may contain additives such as a surfactant and an antifoaming agent, if necessary, to improve the developing action.

[0191] The developing time is preferably from 10 seconds to 5 minutes. The temperature of the developer during development is not particularly defined, but is preferably 20°C or higher, preferably 50°C or lower, and more preferably 40°C or lower.

[0192] Examples of the developing method include a paddle method, a spray method, a dipping method, a brushing method, a slapping method, an ultrasonic method, and the like. Among them, the spray method is suitable for improving the resolution. The spray pressure when the spray method is adopted is preferably from 0.05 MPa to 0.3 MPa.

[0193] After development using the developer, the second composition layer 110 may be further rinsed. The rinsing is preferably performed with a solvent different from the developer. For example, rinsing may be performed using the same type of solvent or water contained in the core resin composition. The rinsing time is preferably from 5 seconds to 1 minute.

[0194] Further, after development using a developer, a desmear treatment may be performed to remove non-exposed portions that cannot be completely removed by development. The desmear treatment may be carried out according to various methods known to those skilled in the art and used in the manufacture of printed wiring boards.

[0195] The method for manufacturing an optical waveguide according to an embodiment of the present invention includes a step (VI) of curing the second composition layer 110 after step (V). This step (VI) generally includes heat-treating the second composition layer 110. The heat treatment conditions may be selected according to the type and amount of the resin component in the photosensitive resin composition of the present invention. For example, the heat treatment conditions in step (VI) may be the same as those for the heat treatment of the first composition layer 210 in step (II).

[0196] FIG. 7 is a schematic cross-sectional view for explaining step (VI) of the method for manufacturing an optical waveguide according to an embodiment of the present invention. By curing the second composition layer 110 in step (VI), as shown in FIG. 7, a core layer 100 as the cured second composition layer is obtained on the lower cladding layer 220.

[0197] FIG. 8 is a schematic cross-sectional view for explaining step (VII) of the method for manufacturing an optical waveguide according to an embodiment of the present invention. As shown in FIG. 8, the method for manufacturing an optical waveguide according to an embodiment of the present invention includes a step (VII) of forming a third composition layer 230 containing a resin composition for cladding on the core layer 100 after step (VI). The third composition layer 230 is generally formed so as 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 so as to cover the core layer 100 and is also formed on the lower cladding layer 220.

[0198] There is no particular limitation on the method for forming the third composition layer 230. For example, the third composition layer 230 may be formed by applying a resin composition for a clad onto the core layer 100 (and, if necessary, onto the lower clad layer 220). The application of the resin composition for a clad to form the third composition layer 230 can be carried out in the same manner as the application of the resin composition for a clad to form the first composition layer 210. Further, after the application of the resin composition for a clad, if necessary, the third composition layer 230 may be dried. The drying of the third composition layer 230 can adopt the same method and conditions as the drying of the first composition layer 210.

[0199] The formation of the third composition layer 230 may be carried out, for example, using a resin sheet for a clad. Specifically, by laminating the photosensitive resin composition layer of the resin sheet for a clad onto the core layer 100 (and, if necessary, the lower clad layer 220), the third composition layer 230 can be formed on the core layer 100. The lamination of the resin sheet for a clad to form the third composition layer 230 can be carried out in the same manner as the lamination of the resin sheet for a clad to form the first composition layer 210. When the third composition layer 230 is formed using a resin sheet for a clad provided with a support, the support may be peeled off in any step.

[0200] The third composition layer 230 formed on the core layer 100 in step (VII) usually contains a resin composition for a clad, and preferably contains only the resin composition for a clad.

[0201] The method for manufacturing an optical waveguide according to an 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 this step (VIII) can usually be carried out in the same manner as the curing of the first composition layer 210.

[0202] FIG. 9 is a schematic cross-sectional view for explaining step (VIII) of a method for manufacturing an optical waveguide according to an embodiment of the present invention. By curing the third composition layer 230 in step (VIII), as shown in FIG. 9, a cured third composition layer 240 is obtained on the core layer 100. This cured third composition layer 240 forms a part of the cladding layer 200, and hereinafter may be referred to as the "upper cladding layer" 240. Then, the cladding layer 200 is formed from this upper cladding layer 240 and the lower cladding layer 220. Therefore, an optical waveguide 10 including the cladding layer 200 including the lower cladding layer 220 and the upper cladding layer 240, and the core layer 100 provided in this cladding layer 200 can be obtained.

[0203] The method for manufacturing the optical waveguide 10 may further include an arbitrary step in combination with the steps described above.

[0204] The method for manufacturing the optical waveguide 10 may include, for example, a step of forming a protective layer (not shown). Further, the method for manufacturing the optical waveguide 10 may include, for example, a step of dicing the manufactured optical waveguide 10.

[0205] The method for manufacturing the optical waveguide 10 may repeat the steps described above. For example, steps (I) to (XI) may be repeated to manufacture an optical waveguide having a multilayer structure in which a core layer and a cladding layer are alternately provided in the thickness direction on the substrate 300.

[0206] [Optoelectronic Hybrid Substrate] The optoelectronic hybrid substrate according to an embodiment of the present invention includes the above-described optical waveguide. Generally, an optoelectronic hybrid 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 the electronic components include passive components such as capacitors, inductors, and resistors; active components such as semiconductor chips; and the like. And the optical waveguide and the wiring of the electrical circuit board can be connected via an optoelectronic conversion element. The optoelectronic conversion element may include a combination of a light-emitting element (e.g., a surface-emitting light-emitting diode) capable of converting electricity into light and a light-receiving element (e.g., a photodiode) capable of converting light into electricity. Further, the optoelectronic hybrid substrate may include an optical element such as a mirror for optical path adjustment.

[0207] As an example of a preferable optoelectronic hybrid substrate, there is one including a chip in which an optical integrated circuit is formed on a silicon wafer. Early practical application of this chip using silicon photonics is expected, and for example, mounting on a semiconductor package is anticipated. The optoelectronic hybrid substrate including 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 and the chip or to connect between a plurality of chips.

[0208] In a chip manufactured by silicon photonics, generally, light with wavelengths of 1310 nm and 1550 nm is often used, and particularly 1310 nm is the mainstream (Shougo Yoshida, Daisuke Suganuma, Akihisa Ishibashi, "Fabrication and Loss Reduction of Single-Mode Polymer Waveguides by Mosquito Method", The 28th Spring Conference of the Electronics Packaging Society, 2014). Therefore, it is preferable that the optical waveguide can transmit light with wavelengths of 1310 nm and 1550 nm or wavelengths close thereto. For example, it is preferable that the optical waveguide can transmit light with a wavelength of 1300 nm to 1320 nm. According to the optical waveguide according to the above-described embodiment, light with these wavelengths can be transmitted.

[0209] Generally, in single-mode and multi-mode, single-mode can achieve faster transmission. Therefore, from the perspective of high-speed transmission, a single-mode optical waveguide is preferred as the optical waveguide applied to the optoelectronic hybrid circuit. In a single-mode optical waveguide, it is preferable that the width of the core layer is small. For example, it is preferable to form a core layer with a width of 10 μm or less, or 5 μm or less. Further, such an optical waveguide having a core layer with a small width is also preferable from the perspective of increasing the degree of freedom in the design of the package when the optical waveguide is applied to a semiconductor package. According to the optical waveguide according to the above-described embodiment, it is possible to reduce the width of the core layer as described above.

[0210] On the other hand, when connecting a plurality of optoelectronic hybrid substrates, those substrates may be connected via an optical fiber. For example, a plurality of optoelectronic hybrid substrates may be installed in a rack, and those optoelectronic hybrid substrates may be connected to each other by an optical fiber. The optical fiber for connecting between such substrates is mainly multi-mode. Therefore, from the perspective of enabling connection with the optical fiber, a multi-mode optical waveguide may be adopted as the optical waveguide provided on the optoelectronic hybrid substrate.

[0211] From the perspective of enhancing versatility, it is desirable that the optical waveguide is applicable to both single-mode and multi-mode. Furthermore, it is desirable to reduce the minimum width of the core layer of those optical waveguides to increase the degree of freedom in the line width of the core layer. According to the optical waveguide according to the above-described embodiment, by using the photosensitive resin composition of the present invention having excellent core-forming properties in the core, a high fine wiring forming ability can be achieved, so that the minimum width of the core layer can be reduced. Also, according to the optical waveguide according to the above-described embodiment, both single-mode and multi-mode optical waveguides can be obtained. Therefore, the optical waveguide according to the above-described embodiment can be applied in a wide range. And while being applicable in such a wide range, the optical waveguide according to the above-described embodiment can suppress the optical transmission loss, so it is suitable for application to the optoelectronic hybrid substrate.

Example

[0212] Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited to these examples. In the following description, "parts" and "%" representing amounts mean "parts by mass" and "mass %", respectively, unless otherwise specified. Also, the operations described below were carried out in the atmosphere at normal temperature and pressure (23°C and 1 atm) unless otherwise specified.

[0213] <Synthesis Example 1: Synthesis of a resin containing a carboxy group and an ethylenic double bond> 325 parts of an epoxy resin having a naphthol aralkyl skeleton with an epoxy equivalent of 330 g / eq. ("ESN-475V", manufactured by Nippon Steel Chemical & Material Co., Ltd.) was placed in a flask equipped with a gas introduction tube, a stirrer, a condenser, and a thermometer, 340 parts of carbitol acetate was added, and the mixture was heated and dissolved. Then, 0.46 part of hydroquinone and 1 part of triphenylphosphine were added. This mixture was heated to 95 - 105°C, 72 parts of acrylic acid was gradually added dropwise, and the reaction was carried out for 16 hours. The reaction product was cooled to 80 - 90°C, 80 parts of tetrahydrophthalic anhydride was added, and the reaction was carried out for 8 hours and then cooled. The amount of the solvent was adjusted to obtain a resin solution (nonvolatile content 70%) with an acid value of 60 mgKOH / g for the solid matter. 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 contained as a repeating unit and accounted for 55% of the total mass of one molecule.

[0214] <Synthesis Example 2: Synthesis of a resin containing a carboxy group and an ethylenic double bond> 162 parts of 1,1'-bis(2,7-diglycidyloxynaphthyl)methane with an epoxy equivalent of 162 g / eq. (「EXA-4700」, manufactured by Dainippon Ink and Chemicals, Inc.) were placed in a flask equipped with a gas inlet tube, a stirrer, a condenser, and a thermometer. 340 parts of carbitol acetate were added, and the mixture was heated and dissolved. 0.46 part of hydroquinone and 1 part of triphenylphosphine were added. The mixture was heated to 95 - 105 °C, and 72 parts of acrylic acid were gradually added dropwise and reacted for 16 hours. The reaction product was cooled to 80 - 90 °C, 80 parts of tetrahydrophthalic anhydride were added, and the mixture was reacted for 8 hours and then cooled. In this way, a resin solution (non-volatile content 70%) with an acid value of 90 mgKOH / g of solid matter was obtained. The weight average molecular weight was 2500. The naphthalene skeleton contained in the obtained naphthalene skeleton-containing ester type acid-modified epoxy acrylate resin was contained as a repeating unit and accounted for 29% of the total mass of one molecule.

[0215] <Production Example 1: Production of Clad Resin Composition> 25 parts of the naphthol aralkyl skeleton-containing ester type acid-modified epoxy acrylate resin (non-volatile fraction 70%) obtained in Synthesis Example 1, 10 parts of a naphthol aralkyl skeleton epoxy resin (「ESN-475V」 manufactured by Nippon Steel Chemical & Material Co., Ltd., epoxy equivalent about 330 g / eq.), 1.3 parts of a photopolymerization initiator (「Omnipol910」 manufactured by IGM), 10 parts of a reactive diluent (「DPHA」 manufactured by Nippon Kayaku Co., Ltd., dipentaerythritol hexaacrylate), and spherical silica surface-treated with an amino-based silane coupling agent (「180nmSX-C1」 manufactured by Admatechs Co., Ltd., specific surface area 20 m 2 / g, average particle size 0.2 μm) 30 parts were mixed with 10 parts of methyl ethyl ketone, and a varnish-like resin composition was prepared using a high-speed rotary mixer.

[0216] <Example 1: Production of Photosensitive Resin Composition> 25 parts of the naphthalene skeleton-containing ester-type acid-modified epoxy acrylate resin (non-volatile content: 70%) obtained in Synthesis Example 2, 10 parts of a naphthalene-type polyfunctional epoxy resin (“HP-4710” manufactured by DIC Corporation, epoxy equivalent: approximately 170 g / eq.), 1.3 parts of a photopolymerization initiator (“Omnipol910” manufactured by IGM), 10 parts of a reactive diluent (“DPHA” manufactured by Nippon Kayaku Co., Ltd., dipentaerythritol hexaacrylate), and 10 parts of methyl ethyl ketone were mixed, and a varnish-like photosensitive resin composition was prepared using a high-speed rotary mixer.

[0217] <Examples 2 to 13, Comparative Examples 1 to 3: Production of Photosensitive Resin Composition> 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 mean parts by mass and are the actually used amounts.

[0218]

Table 1

[0219] The abbreviations, etc. in the table are as follows. (Component (A)) · HP-4710: Naphthalene-type tetrafunctional epoxy resin (“HP-4710” manufactured by DIC Corporation, epoxy equivalent: 170 g / eq.) · ESN-475V: Naphthol aralkyl skeleton epoxy resin (“ESN-475V” manufactured by Nippon Steel Chemical & Material Co., Ltd., epoxy equivalent: approximately 330 g / eq.) · NC3000H: Biphenyl-type epoxy resin (“NC3000H” manufactured by Nippon Kayaku Co., Ltd., epoxy equivalent: 290 g / eq.) · 850: Bisphenol A-type epoxy resin (“850” manufactured by DIC Corporation, epoxy equivalent: approximately 188 g / eq.) (Component (B)) · Synthesis Example 1: Resin containing a carboxy group and an ethylenic double bond synthesized in Synthesis Example 1, non-volatile content: 70%, containing 55% of a naphthol aralkyl skeleton with respect to the entire mass of one molecule · Synthesis Example 2: A resin containing a carboxy group and an ethylenic double bond synthesized in Synthesis Example 2, having a non-volatile content of 70% and containing 29% of a naphthalene skeleton with respect to the total mass of one molecule · CCR-1171H: Cresol novolak skeleton-containing acid-modified epoxy acrylate resin (manufactured by Nippon Kayaku Co., Ltd., acid value 99 mgKOH / g, non-volatile content rate 60%, solvent PGMEA, molecular weight 7500, containing 35% of a cresol novolak skeleton with respect to the total mass of one molecule) · ZCR-1761H: Biphenyl skeleton-containing acid-modified epoxy acrylate resin (manufactured by Nippon Kayaku Co., Ltd., acid value 60 mgKOH / g, non-volatile content rate 60%, solvent PGMEA, molecular weight 3000, containing 57% of a biphenyl skeleton with respect to the total mass of one molecule) (C1) component · Omnipol910: A compound represented by the following structure (manufactured by IGM, molecular weight is 850 or more) In the formula, d represents an integer from 1 to 10.

Chemical formula

Chemical formula

Chemical formula

Chemical formula

[0220] (Manufacture of resin sheet) Using the photosensitive resin compositions produced in Examples 1 to 13 and Comparative Examples 1 to 3 above, a plurality of resin sheets each having a photosensitive resin composition layer with different thicknesses were produced by the following method.

[0221] A polyethylene terephthalate film (Lumirror T6AM manufactured by Toray Industries, Inc., thickness 38 μm, softening point 130 °C) was prepared as a support. The photosensitive resin compositions produced in Examples 1 to 13 and Comparative Examples 1 to 3 were uniformly applied to such a support with a die coater so that the thickness of the photosensitive resin composition layer after drying was 5 μm, 10 μm, or 15 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 stretched polypropylene film, MA-411 manufactured by Oji Fibrex Co., Ltd.) was placed on the surface of the photosensitive resin composition layer and laminated at 80 °C to produce a resin sheet having a three-layer structure of support / photosensitive resin composition layer / cover film.

[0222] A polyethylene terephthalate film (「Lumirror T6AM」manufactured by Toray Industries, Inc., thickness 38 μm, softening point 130 °C) was prepared as a support. The resin composition produced in Production Example 1 was uniformly coated with a die coater so that the thickness of the resin composition layer after drying would be 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 stretched polypropylene film, 「MA-411」manufactured by Oji F-Tex Corporation) was placed on the surface of the photosensitive resin composition layer and laminated at 80 °C to produce a resin sheet having a three-layer structure of support / photosensitive resin composition layer / cover film.

[0223] [Measurement of Coefficient of Thermal Expansion (CTE)] The cover film was peeled off from a resin film having a photosensitive resin composition layer with a thickness of 15 μm, which was produced using the photosensitive resin compositions of Examples 1 to 13 and Comparative Examples 1 to 3. Thereafter, the photosensitive resin composition layer was heat-cured by performing ultraviolet irradiation of 2 J and heating at 170 °C for 60 minutes in a nitrogen atmosphere. Thereafter, the support was peeled off to obtain a cured product for evaluation. The cured product for evaluation was cut to obtain test pieces with a width of 5 mm and a length of 15 mm. Using a thermomechanical analyzer (Thermo Plus, TMA8310 manufactured by Rigaku Corporation), thermomechanical analysis of the above test pieces was performed by the tensile loading method. In the above thermomechanical analysis, after mounting the test piece on the apparatus, two consecutive measurements were performed under the measurement conditions of a load of 1 g and a heating rate of 5 °C / min. By calculating the coefficient of linear thermal expansion (ppm) from 25 °C to 150 °C in the second measurement, the coefficient of linear thermal expansion of the cured product was measured and evaluated according to the following criteria. 〇: Coefficient of linear thermal expansion is less than 80 ppm △: Coefficient of linear thermal expansion is 80 ppm or more and less than 100 ppm ×: Coefficient of linear thermal expansion is 100 ppm or more

[0224] [Evaluation of Warpage] The photosensitive resin composition layer (with a thickness of 15 μm) of the resin sheet with a support was laminated on one side of a core material (manufactured by Showa Denko Materials Co., Ltd., "E700GR", size: 16 cm × 12 cm) from which all 200-μm-thick copper had been etched out using a vacuum laminator (manufactured by Nikkō Materials Co., Ltd., VP160) to produce an evaluation laminate B in which the core material, the photosensitive resin composition layer, and the support were laminated in this order. The crimping conditions were a vacuum evacuation time of 30 seconds, a crimping temperature of 80°C, a crimping pressure of 0.7 MPa, and a pressurization time of 30 seconds. After producing the evaluation laminate B, it was left standing at room temperature (25°C) for 30 minutes or more.

[0225] Using a pattern forming device from above the support of the evaluation laminate B, ultraviolet exposure was performed at an exposure energy at which the number of remaining gloss steps of the 41-step tablet was 8 steps. A quartz glass mask with no exposure pattern was used. After leaving it standing at room temperature for 30 minutes, the support was peeled off from the evaluation laminate B. A 1% by mass aqueous sodium carbonate solution at 30°C was sprayed onto the entire surface of the photosensitive resin composition layer on the evaluation laminate B for 1 minute at a spray pressure of 0.2 MPa for spray development. After spray development, ultraviolet irradiation at 2 J / cm 2 was performed, and further heat treatment at 170°C for 1 hour was performed to cure the photosensitive resin composition layer to obtain an evaluation core material A. Each evaluation core material A was placed on a horizontal table, one long side was fixed to the table, and the height of the other long side from the table (the amount of warp in the short side direction) was measured and evaluated according to the following criteria. 〇: The amount of warp in the short side direction is less than 5 mm △: The amount of warp in the short side direction is greater than 5 mm and less than 10 mm ×: The amount of warp in the short side direction is 10 mm or more

[0226] [Evaluation of resolution (core formation ability)] A glass epoxy substrate (copper-clad laminate) having a copper layer with a thickness of 18 μm was roughened with a surface treatment agent (CZ8100, manufactured by Meck) containing an organic acid to prepare a substrate. A resin sheet with a photosensitive resin composition layer having a thickness of 5 μm, which was produced using the resin composition prepared in Production Example 1, was laminated on the previous substrate at 80 °C, and the support was peeled off to form a photosensitive resin composition layer. Then, using a projection exposure apparatus ("UFX-2240" manufactured by Ushio Electric Co., Ltd.), ultraviolet exposure was performed at an exposure energy at which the number of remaining gloss steps of a 41-step tablet was 8 steps. A quartz glass mask without an exposure pattern was used. After standing at room temperature for 30 minutes, the support was peeled off. A 1% by mass aqueous sodium carbonate solution at 30 °C was sprayed onto the entire surface of the photosensitive resin composition layer for 1 minute at a spray pressure of 0.2 MPa for spray development. After spray development, ultraviolet irradiation at 2 J / cm 2 was performed, and further heat treatment was carried out at 170 °C for 1 hour in a nitrogen atmosphere to form a lower cladding layer on the copper-clad laminate.

[0227] A cover film was peeled off from a resin sheet having a photosensitive resin composition layer with a thickness of 10 μm, which was produced using the photosensitive resin composition manufactured 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 laminated using a vacuum laminator ("VP160" manufactured by Nikko Materials Co., Ltd.) to form a photosensitive resin composition layer on the lower cladding layer. The lamination conditions were a vacuum evacuation time of 30 seconds, a crimping temperature of 100 °C, a crimping pressure of 0.7 MPa, and a pressurization time of 30 seconds. Thereby, a laminate including a copper-clad laminate, a lower cladding layer, and a resin sheet in this order was obtained. Then, the support was peeled off to expose the photosensitive resin composition layer.

[0228] Using a projection exposure apparatus (USHIO INC.'s "UFX-2240"), ultraviolet exposure was performed on the photosensitive resin composition layer at an exposure energy at which the number of remaining gloss steps of the 41-step tablet was 8 steps. The exposure was performed using a quartz glass mask having a first mask pattern for drawing a straight line at an L / S (line / space) of 10 μm / 10 μm, a second mask pattern for drawing a straight line at an L / S (line / space) of 5 μm / 5 μm, and a third mask pattern for drawing a straight line at an L / S (line / space) of 3 μm / 3 μm. After the exposure, the sample was allowed to stand at room temperature for 30 minutes, and then the support was peeled off. A 1 mass% aqueous sodium carbonate solution at 30 °C was sprayed onto the entire surface of the photosensitive resin composition layer for 1 minute at a spray pressure of 0.2 MPa for spray development. After the spray development, ultraviolet irradiation at 2 J / cm 2 was performed, and further heat treatment at 170 °C for 1 hour was performed in a nitrogen atmosphere to obtain a sample including a copper-clad laminate, a lower cladding layer, and a line layer (a layer formed of a cured product of the resin composition) in this order.

[0229] The obtained sample was observed with a scanning electron microscope (SEM) (magnification: 2000 times), and the minimum fine line formation width (the width of the line layer having the smallest width among the formed line layers) was measured. The aspect ratio was calculated by dividing the thickness of the line layer by the minimum fine line formation width. The resolution was evaluated according to the following criteria. The line width represents the width of the line layer. 〇: The aspect ratio is 1 or more for all line layers having a line width of 10 μm or less. △: The aspect ratio is 0.6 or more and less than 1 for all line layers having a line width of 10 μm or less. ×: The aspect ratio of at least one of the line layers having a line width of 10 μm or less is less than 0.6.

[0230] [Measurement of Optical Transmission Loss] (1-1. Formation of Lower Cladding Layer) A cover film was peeled off from a resin sheet having a photosensitive resin composition layer with a thickness of 10 μm, which was produced using the resin composition produced in Production Example 1. The resin sheet was placed on a 4-inch silicon wafer such that the photosensitive resin composition layer was in contact with the silicon wafer, and laminated using a vacuum laminator (“VP160” manufactured by Nippon Materials Co., Ltd.). The lamination conditions were a vacuum evacuation time of 30 seconds, a crimping temperature of 100° C., a crimping pressure of 0.7 MPa, and a pressurization time of 30 seconds. Thereafter, the support was peeled off to obtain an intermediate laminate I including a silicon wafer and a photosensitive resin composition layer.

[0231] The photosensitive resin composition layer of the intermediate laminate I was subjected to ultraviolet exposure using a projection exposure apparatus (“UFX-2240” manufactured by USHIO INC.) at an exposure energy such that the number of remaining gloss steps of a 41-step tablet was 8 steps. After the exposure, ultraviolet irradiation of 2 J / cm 2 was performed. The intermediate laminate I was placed in a clean oven, heated from room temperature to 170° C., and after reaching 170° C., heat treatment was performed for 60 minutes in a nitrogen atmosphere to cure the photosensitive resin composition layer. By curing the photosensitive resin composition layer, a lower cladding layer was formed, and an intermediate laminate II including a silicon wafer and the lower cladding layer was obtained.

[0232] (1-2. Formation of core layer) A cover film was peeled off from a resin sheet having a photosensitive resin composition layer with a thickness of 5 μm, which was produced using the photosensitive resin composition produced in the Examples and Comparative Examples. The resin sheet was placed on the surface of the lower cladding layer of the intermediate laminate II such that the photosensitive resin composition layer was in contact with the lower cladding layer, and laminated using a vacuum laminator (“VP160” manufactured by Nippon Materials Co., Ltd.). The lamination conditions were a vacuum evacuation time of 30 seconds, a crimping temperature of 100° C., a crimping pressure of 0.7 MPa, and a pressurization time of 30 seconds. Thereafter, the support was peeled off to obtain an intermediate laminate III including a silicon wafer, an undercladding layer, and a photosensitive resin composition layer in this order.

[0233] On the photosensitive resin composition layer of the intermediate laminate III, ultraviolet exposure was performed using a projection exposure apparatus ("UFX-2240" manufactured by USHIO INC.) at an exposure energy at which the number of remaining gloss steps of the 41-step tablet was 8 steps. The exposure was performed using a quartz glass mask having a mask pattern capable of drawing a plurality of straight lines with a length of 1 cm at L / S (line / space) of 5 μm / 100 μm, a mask pattern capable of drawing a plurality of straight lines with a length of 2 cm at L / S (line / space) of 5 μm / 100 μm, and a mask pattern capable of drawing a plurality of straight lines with a length of 3 cm at 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 interval between the core layers. After exposure, it was allowed to stand at room temperature for 30 minutes, and then the support was peeled off. A 1 mass% aqueous sodium carbonate solution at 30 °C was sprayed on the entire surface of the photosensitive resin composition layer for 1 minute at a spray pressure of 0.2 MPa for spray development. After spray development, ultraviolet irradiation of 2 J / cm 2 was performed. Thereafter, the intermediate laminate III was put into a clean oven, heated from room temperature to 170 °C, and after reaching 170 °C, heat treatment was performed for 60 minutes in a nitrogen atmosphere to cure the photosensitive resin composition layer.

[0234] By curing the photosensitive resin composition layer, a core layer was formed, and an intermediate laminate IV including a silicon wafer, a lower cladding layer, and a core layer in this order was obtained.

[0235] (1-3. Formation of the upper cladding layer) The cover film was peeled off from a resin sheet having a photosensitive resin composition layer with a thickness of 20 μm, which was produced using the resin composition produced in Production Example 1. The resin sheet was placed on the core layer of the intermediate laminate IV so that the photosensitive resin composition layer and the core layer were in contact with each other, and they were laminated using a vacuum laminator ("VP160" manufactured by Nippon Materials Co., Ltd.). The lamination conditions were a vacuum evacuation time of 30 seconds, a crimping temperature of 100 °C, a crimping pressure of 0.7 MPa, and a pressurization time of 30 seconds. Thereafter, the support was peeled off to obtain an intermediate laminate V including a silicon wafer, a lower cladding layer, a core layer, and a photosensitive resin composition layer in this order. On the photosensitive resin composition layer of the intermediate laminate V, ultraviolet exposure was performed using a projection exposure apparatus ("UFX-2240" manufactured by USHIO INC.) at an exposure energy such that the number of remaining gloss steps of the 41-step tablet was 8 steps. After exposure, ultraviolet irradiation of 2 J / cm 2 was performed. The intermediate laminate V was put into a clean oven, heated from room temperature to 170 °C, and after reaching 170 °C, heat treatment was performed for 60 minutes in a nitrogen atmosphere to cure the photosensitive resin composition layer. By curing the photosensitive resin composition layer, an upper cladding layer was formed, and a sample laminate including a silicon wafer, a lower cladding layer, a core layer, and an upper cladding layer in this order was obtained.

[0236] In this sample laminate, the combination of the lower cladding layer and the upper cladding layer constituted the cladding layer. Therefore, an optical waveguide including the cladding layer and the core layer in the cladding layer was obtained. Further, in this sample laminate, the core layer had linear patterns with lengths of 1 cm, 2 cm, and 3 cm corresponding to the mask patterns of the quartz glass mask, and the widths (line widths) and intervals (spaces) of the core layers included in those patterns were the same as the widths (line widths) and intervals (spaces) of the mask patterns.

[0237] [Evaluation of optical waveguide] [Measurement of optical transmission loss of calibration optical system] The transmission loss of an optical system having a configuration excluding the test substrate and the condenser module from the optical system for measuring the transmission loss of the test substrate described later was measured. That is, on a vibration isolation table covered with a dark curtain, a light source (1310 nm light source, "LPSC-1310-FC" manufactured by THORLABS) and a light receiver (optical power meter "N7742" manufactured by Keysight Technologies) were connected via an optical fiber (input fiber) to obtain a calibration optical system. The light source was caused to emit light, and the intensity of the light that entered the light receiver was measured by the light receiver to measure the loss of this calibration optical system.

[0238] [Preparation of test substrate] From the sample laminates manufactured using the resin compositions of the examples and comparative examples, the core layer and the clad layer around it were cut out at the portion where the core layer was formed to obtain a test substrate provided with an optical transmission path.

[0239] (Measurement of optical transmission loss) The test substrate was placed on a vibration isolation table covered with a dark curtain. A condensing module (numerical aperture 0.18) was connected to one end (incident end) of the optical waveguide of the test substrate, and a light source (1310 nm light source, "LPSC-1310-FC" manufactured by THORLABS) was connected to the condensing module via an optical fiber (incident fiber). Also, another condensing module (numerical aperture 0.18) was connected to the other end (emission end) of the optical waveguide of the test substrate, and a light receiver (optical power meter "N7742" manufactured by Keysight Technologies) was connected to the condensing module via an optical fiber (emission fiber). By the above operations, an optical system was obtained in which the light emitted from the light source passed through the optical fiber (incident fiber), condensing module, optical waveguide, condensing module, and optical fiber (emission fiber) in this order and then entered the light receiver. Hereinafter, this optical system may be referred to as a sample optical system. The light source was made to emit light, and the intensity of the light that entered the light receiver was measured by the light receiver to measure the loss of the sample optical system.

[0240] From the loss of the sample optical system, the loss of the calibration optical system was subtracted to obtain the loss of the optical waveguide included in the test substrate.

[0241] (Measurement of transmission loss (dB / cm) of optical waveguide) The measurement of the loss of the optical waveguide was performed for each of an optical waveguide with a length of 1 cm, an optical waveguide with a length of 2 cm, and an optical waveguide with a length of 3 cm. Then, the measurement results were plotted in a coordinate system with the length of the optical waveguide on the horizontal axis and the loss of the optical waveguide on the vertical axis to obtain three coordinate points representing the measurement results. The approximate straight line of these three points was calculated by the least squares method, and the slope of the approximate straight line was obtained as the loss per unit distance (transmission loss) of the optical waveguide and evaluated according to the following criteria. 〇: Optical transmission loss is less than 1 dB / cm △: Optical transmission loss is greater than 1 dB / cm and less than 2 dB / cm ×: Optical transmission loss is greater than 2 dB / cm

[0242] (Mode confirmation) The light receiver was removed and replaced with an infrared camera (InGaAs camera with a 100x objective lens). The light source was made to emit light, and the light emitted from the end of the optical fiber (output fiber) was photographed with the infrared camera. When only one circular light edge was observed, it was determined to be single mode. Also, when multiple edges were observed, it was determined to be multimode.

[0243] [Measurement of absorbance of solution of photosensitive resin composition] A solution of the photosensitive resin composition contained in the resin varnish produced in the above-described production example was prepared, and the absorbance of the solution was measured by the following method. That is, MEK (methyl ethyl ketone) and a mixed solvent of cyclopentanone (MEK:pentanone = 1:1) were mixed with the photosensitive resin compositions of Examples 1 to 13 and Comparative Examples 1 to 3 to prepare a solution of the photosensitive resin composition with a concentration of 20% by mass. This solution was put into a 1-cm quartz cell, and the absorbance Abs at a wavelength of 1310 nm was measured with an ultraviolet-visible-near-infrared spectrophotometer (V-770 manufactured by Nippon Bunko Co., Ltd.), and evaluated according to the following criteria. ◎: Absorbance is less than 0.0025 〇: Absorbance is 0.0025 or more and less than 0.0050 △: Absorbance is 0.0050 or more and less than 0.0100 ×: Absorbance is 0.0100 or more

[0244]

Table 2

[0245] Examples 1 to 13 using a photosensitive resin composition containing component (A) and component (B) having the same skeleton as component (A), and component (C) are excellent in core formation, suppress the occurrence of warpage, and reduce optical transmission loss. It can also be seen that the average linear thermal expansion rate and absorbance also give good results. On the other hand, Comparative Examples 1 to 2 using component (B) that does not contain the same skeleton as component (A) are inferior in at least one of core formation, warpage occurrence, and optical transmission loss compared to Examples 1 to 13, and furthermore, at least one of the average linear thermal expansion rate and absorbance is inferior compared to Examples 1 to 13.

Explanation of symbols

[0246] 10 Optical waveguide 100 Core layer 110 Second composition layer 111 Exposed part 112 Unexposed part 200 Clad layer 210 First composition layer 220 Cured first composition layer (lower clad layer) 230 Third composition layer 240 Cured third composition layer (upper clad layer) 300 Substrate 400 Mask 410 Light-transmitting part 420 Light-shielding part

Claims

1. (A) an epoxy resin, (B) an acid-modified epoxy (meth)acrylate resin, and (C) a photopolymerization initiator, and contains the skeleton B other than the epoxy-modified part in the component (B) is the same skeleton as the skeleton A other than the epoxy group in the component (A), the skeleton B other than the epoxy-modified part in the component (B) contains an aromatic skeleton, the aromatic skeleton contains a polycyclic aromatic skeleton, when the content of the component (A) is 100% by mass of the non-volatile components of the photosensitive resin composition, it is 10% by mass or more and 40% by mass or less, when the content of the component (B) is 100% by mass of the non-volatile components of the photosensitive resin composition, it is 25% by mass or more and 65% by mass or less, a photosensitive resin composition.

2. The photosensitive resin composition according to claim 1, wherein the skeleton B other than the epoxy-modified part in the component (B) is 5% or more based on the total mass of one molecule of the component (B).

3. The photosensitive resin composition according to claim 1, wherein the polycyclic aromatic skeleton contains a condensed ring.

4. The photosensitive resin composition according to claim 1, wherein the skeleton A and the skeleton B contain a naphthalene skeleton or a naphthol aralkyl skeleton.

5. The photosensitive resin composition according to claim 1, wherein the component (C) contains a photopolymerization initiator (C1) having a molecular weight of 420 or more.

6. The photosensitive resin composition according to claim 1, wherein the component (C) contains a photopolymerization initiator (C2) having a molecular weight of less than 420.

7. The photosensitive resin composition according to claim 6, wherein the component (C2) contains any one of an oxime ester-based photopolymerization initiator, an α-amino ketone-based photopolymerization initiator, and an acylphosphine-based photopolymerization initiator.

8. The photosensitive resin composition according to claim 1, further containing (D) a photosensitizer.

9. The photosensitive resin composition according to claim 1, further containing (E) an inorganic filler having an average particle diameter of 100 nm or less.

10. The photosensitive resin composition according to claim 1, which is for sodium carbonate development.

11. The photosensitive resin composition according to claim 1, which is for manufacturing a core layer of an optical waveguide.

12. A resin sheet having a support and a photosensitive resin composition layer formed on the support and composed 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 including a photosensitive resin composition for a core and a resin composition for a clad, The photosensitive resin composition set, wherein the photosensitive resin composition for the core includes the photosensitive resin composition according to any one of claims 1 to 11.

15. A optical waveguide comprising a core layer and a clad layer, The optical waveguide, wherein the core layer includes a cured product of the photosensitive resin composition according to any one of claims 1 to 11.

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

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

18. An optoelectronic hybrid mounting substrate including the optical waveguide according to claim 15.

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