Photosensitive resin composition set

Abstract

To provide a photosensitive resin composition set and the like which enable manufacture of an optical waveguide that is excellent in developability and flame retardancy, is low in shrinkage, and is small in optical transmission loss.SOLUTION: There is provided a photosensitive resin composition set containing a resin composition for a core and a resin composition for a clad. The resin composition for the core and the resin composition for the clad each contain (A) a carboxyl group-containing resin, (B) an epoxy resin, (C) a photocurable resin, (D) a photopolymerization initiator, and (E) one or more flame retardants selected from a phosphate-based compound and a phosphazene compound. When Eclad represents a content (mass%) of the component (E) in the resin composition for the clad with a non-volatile component of the resin composition for the clad being 100 mass%, and Ecore represents a content (mass%) of the component (E) in the resin composition for the core with a non-volatile component of the resin composition for the core being 100 mass%, there is satisfied a range of Eclad-Ecore being 0.6 or more and 12 or less.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a photosensitive resin composition set, and further to a photosensitive resin sheet set, the photosensitive resin composition set, an optical waveguide, a method for manufacturing an optical waveguide, an opto-electrical hybrid board, and a method for manufacturing an opto-electrical hybrid board. [Background technology]

[0002] Technological advances such as 5G communications, autonomous driving, IoT, artificial intelligence, and big data are driving demands for ultra-high-speed and high-capacity communications. Semiconductor packages, which underpin these technologies, have traditionally supported high-speed communications by passing high-frequency current through them. However, in recent years, issues such as noise generation, communication loss, and heat generation due to high-speed communications have become apparent. To address these issues, active efforts have been made in recent years to implement optical circuits on electrical wiring boards and achieve energy-saving, low-latency, and high-speed communications (Patent Documents 1 and 2). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2019-211540 [Patent Document 2] Patent No. 5771978 Summary of the Invention [Problem to be solved by the invention]

[0004] Research into the introduction of silicon photonics is being actively conducted, particularly in data centers where high-speed transmission is required. Silicon photonics is highly compatible with conventional LSI manufacturing processes. Therefore, it is expected that the use of silicon photonics will enable the formation of nanometer-sized thin-wire waveguides at low cost, based on the technology cultivated in electronic circuit integration technology.

[0005] For example, silicon photonics is expected to enable the formation of optical integrated circuits on chips using thin-wire waveguides. When manufacturing an optoelectronic hybrid board incorporating such a chip, it is necessary to provide an optical waveguide on the optoelectronic hybrid board in order to extract signal light from the thin-wire waveguide within the chip to the outside of the chip and connect it to the wiring between chips. From the viewpoint of efficiently forming a fine optical waveguide, it is desirable to form the optical waveguide using a cured product of a photosensitive resin composition. Furthermore, since this optoelectronic hybrid board is required to have the same reliability as a printed circuit board, including flame retardancy, it is desirable for there to be no significant change in optical transmission loss, and at the same time, it is desirable for the board to have properties sufficient to withstand the manufacturing process of the printed circuit board.

[0006] Furthermore, when the core and cladding are formed from a cured product of a photosensitive resin composition, it is necessary to change the composition, ratio, etc. of the resin components contained in the photosensitive resin composition in order to adjust the refractive index between the core and the cladding. However, this may result in a decrease in developability or an increase in optical transmission loss due to a change in the shrinkage rate before and after curing the photosensitive resin composition.

[0007] The present invention has been devised in view of the above-mentioned problems, and aims to provide a photosensitive resin composition set capable of producing an optical waveguide having excellent developability and flame retardancy, a low shrinkage rate, and small optical transmission loss; a photosensitive resin sheet set; an optical waveguide; a method for producing an optical waveguide; an opto-electrical hybrid board; and a method for producing an opto-electrical hybrid board. [Means for solving the problem]

[0008] As a result of intensive research, the present inventors have found that the above-mentioned problems can be solved by having the core resin composition and the clad resin composition each contain (A) a resin containing a carboxyl group, (B) an epoxy resin, (C) a photocurable resin, (D) a photopolymerization initiator, and (E) one or more flame retardants selected from phosphate ester compounds and phosphazene compounds, and by adjusting the content of component (E) contained in the core resin composition and the clad resin composition so that the content of component (E) satisfies a predetermined relationship, thereby completing the present invention.

[0009] That is, the present invention includes the following. [1] A photosensitive resin composition set including a core resin composition and a clad resin composition, The core resin composition and the clad resin composition each comprise: (A) a resin containing a carboxyl group, (B) epoxy resin, (C) Photocurable resin, (D) a photoinitiator, and (E) one or more flame retardants selected from phosphate ester compounds and phosphazene compounds, The content (mass%) of component (E) in the clad resin composition is defined as E when the nonvolatile components of the clad resin composition are taken as 100 mass%. clad The content (mass%) of component (E) in the core resin composition is defined as E when the nonvolatile components of the core resin composition are defined as 100 mass%. core When E clad -E core A photosensitive resin composition set in which the value of [2] The photosensitive resin composition set according to [1], wherein the phosphate ester compound in the component (E) has either a compound represented by the following formula (E-1) or a compound represented by the following formula (E-2): [ka] In formula (E-1), R 1 ~R 20 each independently represents a hydrogen atom, a hydroxy group, or an alkyl group having 1 to 6 carbon atoms which may have a substituent; W 1 represents a group represented by formula (E-1a) or a group represented by formula (E-1b). In formula (E-1b), R represents an oxygen atom or a divalent hydrocarbon group having 1 to 20 carbon atoms which may have a substituent. In formula (E-2), R 21 ~R 28each independently represents a hydrogen atom, a hydroxy group, or an alkyl group having 1 to 6 carbon atoms which may have a substituent; R 29 represents a (meth)acryloyl group, an oxygen atom, a divalent hydrocarbon group of 1 to 10 carbon atoms which may have a substituent, a monovalent hydrocarbon group of 1 to 20 carbon atoms which may have a substituent, or a monovalent group consisting of a combination thereof. [3] The photosensitive resin composition set according to [1] or [2], wherein the phosphazene compound in the component (E) has a compound represented by the following formula (E-3): [ka] (In formula (E-3), R 31 and R 32 each independently represents a hydrogen atom, a hydroxy group, or an alkyl group having 1 to 6 carbon atoms which may have a substituent; n represents an integer of 3 to 25; and m1 and m2 each independently represent an integer of 0 to 5. [4] The photosensitive resin composition set according to any one of [1] to [3], wherein the content of phosphorus atoms in the core resin composition is 0.01% by mass or more and 10% by mass or less, when the non-volatile components of the core resin composition are taken as 100% by mass. [5] The photosensitive resin composition set according to any one of [1] to [4], wherein the content of phosphorus atoms in the cladding resin composition is 0.01% by mass or more and 10% by mass or less, when the non-volatile components of the cladding resin composition are taken as 100% by mass. [6] The photosensitive resin composition set according to any one of [1] to [5], wherein the component (A) contains at least one of an aralkyl resin, a naphthol aralkyl resin, and a cardo resin. [7] The content of component (A) when the non-volatile components of the core resin composition are 100% by mass is A core The content of component (B) when the nonvolatile components of the core resin composition are taken as 100% by mass is defined as B core When A core / B core The photosensitive resin composition set according to any one of [1] to [6], wherein is 0.3 or more and 5 or less. [8] The content of component (A) when the non-volatile components of the core resin composition are 100% by mass is A core The content of component (C) when the nonvolatile components of the core resin composition are taken as 100% by mass is defined as C core When A core / C core The photosensitive resin composition set according to any one of [1] to [7], wherein is 0.1 or more and 3 or less. [9] The content of component (A) when the nonvolatile components of the cladding resin composition are 100% by mass is A clad The content of component (B) when the nonvolatile components of the cladding resin composition are taken as 100% by mass is defined as B clad When A clad / B clad The photosensitive resin composition set according to any one of [1] to [8], wherein is 0.3 or more and 5 or less.

[10] The content of component (A) when the nonvolatile components of the cladding resin composition are 100% by mass is A clad The content of component (C) when the nonvolatile components of the cladding resin composition are taken as 100% by mass is defined as C clad When A clad / C clad The photosensitive resin composition set according to any one of [1] to [9], wherein is 0.1 or more and 3 or less.

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

[10] , which is a photosensitive resin composition set for producing an optical waveguide.

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

[11] , which is a photosensitive resin composition set for producing an optical waveguide capable of transmitting light having a wavelength of 1300 nm to 1320 nm.

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

[12] , which is a photosensitive resin composition set for producing a single-mode optical waveguide.

[14] A photosensitive resin sheet set including a core resin sheet and a clad resin sheet, the core resin sheet is provided with a resin composition layer containing the core resin composition in the photosensitive resin composition set according to any one of [1] to

[13] ; A photosensitive resin sheet set, wherein the cladding resin sheet comprises a resin composition layer containing the cladding resin composition in the photosensitive resin composition set according to any one of [1] to

[13] .

[15] An optical waveguide having a core layer and a clad layer, The core layer, (A) a resin containing a carboxyl group, (B) epoxy resin, (C) Photocurable resin, (D) a photoinitiator, and (E) one or more flame retardants selected from phosphate ester compounds and phosphazene compounds, The cladding layer is (A) a resin containing a carboxyl group, (B) epoxy resin, (C) Photocurable resin, (D) a photoinitiator, and (E) one or more flame retardants selected from phosphate ester compounds and phosphazene compounds, The content (mass%) of component (E) in the clad resin composition is defined as E when the nonvolatile components of the clad resin composition are taken as 100 mass%. clad The content (mass%) of component (E) in the core resin composition is defined as E when the nonvolatile components of the core resin composition are defined as 100 mass%. core When E clad -E core An optical waveguide in which

[16] An optical / electrical hybrid board comprising the optical waveguide according to

[15] .

[17] A step of forming a first composition layer containing a cladding resin composition; curing the first composition layer; forming a second composition layer containing a core resin composition on the first composition layer; a step of exposing the second composition layer to light; a step of subjecting the second composition layer to a development treatment; curing the second composition layer; forming a third composition layer containing a cladding resin composition on the second composition layer; and curing the third composition layer in this order, The core resin composition and the clad resin composition each comprise: (A) a resin containing a carboxyl group, (B) epoxy resin, (C) Photocurable resin, (D) a photoinitiator, and (E) one or more flame retardants selected from phosphate ester compounds and phosphazene compounds, The content (mass%) of component (E) in the clad resin composition is defined as E when the nonvolatile components of the clad resin composition are taken as 100 mass%. clad The content (mass%) of component (E) in the core resin composition is defined as E when the nonvolatile components of the core resin composition are defined as 100 mass%. core When E clad -E core A method for manufacturing an optical waveguide, wherein the value satisfies 0.6 to 12.

[18] A step of forming a first composition layer containing a cladding resin composition; curing the first composition layer; forming a second composition layer containing a core resin composition on the first composition layer; a step of exposing the second composition layer to light; a step of subjecting the second composition layer to a development treatment; curing the second composition layer; forming a third composition layer containing a cladding resin composition on the second composition layer; and curing the third composition layer in this order, The core resin composition and the clad resin composition each comprise: (A) a resin containing a carboxyl group, (B) epoxy resin, (C) Photocurable resin, (D) a photoinitiator, and (E) one or more flame retardants selected from phosphate ester compounds and phosphazene compounds, The content (mass%) of component (E) in the clad resin composition is defined as E when the nonvolatile components of the clad resin composition are taken as 100 mass%. clad The content (mass%) of component (E) in the core resin composition is defined as E when the nonvolatile components of the core resin composition are defined as 100 mass%. core When E clad -E core A method for manufacturing an optical / electrical hybrid board, wherein the value satisfies 0.6 to 12. [Effects of the Invention]

[0010] According to the present invention, it is possible to provide a photosensitive resin composition set capable of producing an optical waveguide that has excellent developability and flame retardancy, a low shrinkage rate, and small optical transmission loss; a photosensitive resin sheet set; an optical waveguide; a method for producing an optical waveguide; an opto-electrical hybrid board; and a method for producing an opto-electrical hybrid board. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a perspective view schematically showing an optical waveguide according to one embodiment of the present invention. [Figure 2] FIG. 2 is a schematic cross-sectional view illustrating step (I) of the method for producing an optical waveguide according to one embodiment of the present invention. [Figure 3] FIG. 3 is a schematic cross-sectional view illustrating step (II) of the method for producing an optical waveguide according to one embodiment of the present invention. [Figure 4] FIG. 4 is a schematic cross-sectional view illustrating step (III) of the method for producing an optical waveguide according to one embodiment of the present invention. [Figure 5] FIG. 5 is a schematic cross-sectional view illustrating step (IV) of the method for producing an optical waveguide according to one embodiment of the present invention. [Figure 6] FIG. 6 is a schematic cross-sectional view illustrating step (V) of the method for producing an optical waveguide according to one embodiment of the present invention. [Figure 7]FIG. 7 is a schematic cross-sectional view illustrating step (VI) of the method for producing an optical waveguide according to one embodiment of the present invention. [Figure 8] FIG. 8 is a schematic cross-sectional view illustrating step (VII) of the method for producing an optical waveguide according to one embodiment of the present invention. [Figure 9] FIG. 9 is a schematic cross-sectional view illustrating step (VIII) of the method for producing an optical waveguide according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0012] The photosensitive resin composition set, photosensitive resin sheet set, optical waveguide using them, method for manufacturing an optical waveguide, opto-electrical hybrid board, and method for manufacturing an opto-electrical hybrid board of the present invention will be described in detail below.

[0013] [Photosensitive resin composition set] The photosensitive resin composition set of the present invention includes a core resin composition and a clad resin composition. The core resin composition can be suitably used as a photosensitive resin composition for forming a core layer of an optical waveguide, and the clad resin composition can be suitably used as a photosensitive resin composition for forming a clad layer of an optical waveguide. The photosensitive resin composition set can be used to produce an optical waveguide having a core layer containing a cured product of the core resin composition and a clad layer containing a cured product of the clad resin composition.

[0014] The core resin composition and the clad resin composition of the present invention each contain (A) a resin containing a carboxyl group, (B) an epoxy resin, (C) a photocurable resin, (D) a photopolymerization initiator, and (E) one or more flame retardants selected from phosphate esters and phosphazenes, and the content (mass%) of component (E) in the clad resin composition is defined as E when the nonvolatile components of the clad resin composition are taken as 100 mass%. clad The content (mass%) of component (E) in the core resin composition is defined as E when the nonvolatile components of the core resin composition are defined as 100 mass%. core When E clad -Ecore is 0.6 or more and 12 or less. Such a photosensitive resin composition set allows the production of an optical waveguide with excellent flame retardancy and low optical transmission loss. In addition, the rate of change in optical transmission loss before and after a high temperature storage test (HTS test) is usually small, and since the core and clad resin compositions are photosensitive resin compositions, they also have excellent developability.

[0015] As described above, the core and clad resin compositions each contain (A) a resin containing a carboxyl group, (B) an epoxy resin, (C) a photocurable resin, (D) a photopolymerization initiator, and (E) one or more flame retardants selected from phosphate esters and phosphazenes. clad -E core The types of components and / or their blending ratios are different so that the ρ is 0.6 or more and 12 or less. The core and clad resin compositions may each further contain optional components such as (F) a curing accelerator, (G) a solvent, and (H) other additives, as necessary. Each component contained in the core and clad resin compositions will be described in detail below. Hereinafter, the core resin composition and the clad resin composition will sometimes be collectively referred to simply as the "resin composition."

[0016] <(A) Carboxyl group-containing resin> The resin composition contains a carboxyl group-containing resin as component (A). By including component (A) in the resin composition, resolution can be improved.

[0017] As component (A), a compound having a carboxyl group and enabling alkaline development can be used. Such a compound is preferably a resin having both a carboxyl group and an ethylenically unsaturated group in one molecule. That is, component (A) is preferably a resin containing an ethylenically unsaturated group and a carboxyl group.

[0018] The ethylenically unsaturated group has a carbon-carbon double bond, and examples thereof include vinyl, allyl, propargyl, butenyl, ethynyl, phenylethynyl, maleimide, nadimide, and (meth)acryloyl groups. From the viewpoint of photoradical polymerization reactivity, (meth)acryloyl groups are preferred. The term "(meth)acryloyl group" encompasses methacryloyl, acryloyl, and combinations thereof. When component (A) contains an ethylenically unsaturated group, photoradical polymerization becomes possible. The number of ethylenically unsaturated groups per molecule of component (A) may be one or two or more. Furthermore, when component (A) contains two or more ethylenically unsaturated groups per molecule, the ethylenically unsaturated groups may be the same or different.

[0019] Furthermore, since component (A) contains a carboxyl group, a resin composition containing component (A) exhibits solubility in an alkaline solution (for example, a 1% by mass aqueous solution of sodium carbonate as an alkaline developer). The number of carboxyl groups per molecule of component (A) may be one or two or more.

[0020] One embodiment of the component (A) is an acid-modified epoxy (meth)acrylate resin.

[0021] In one embodiment, the acid-modified epoxy (meth)acrylate resin may be capable of photoradical polymerization due to the presence of a (meth)acryloyl group. The number of (meth)acryloyl groups per molecule of the acid-modified epoxy (meth)acrylate resin may be one or two or more.

[0022] The acid-modified epoxy (meth)acrylate resin preferably has both a (meth)acryloyl group and a carboxyl group, and is capable of photoradical polymerization and alkali development.

[0023] The acid-modified epoxy(meth)acrylate resin can be produced by acid-modifying an epoxy(meth)acrylate resin by a known method, for example, by reacting an epoxy resin with acrylic acid or methacrylic acid.

[0024] The epoxy resin for producing the epoxy (meth)acrylate resin is not particularly limited as long as it is a compound having an epoxy group in the molecule, and examples thereof include bisphenol-type epoxy resins such as 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, and modified bisphenol F-type epoxy resins obtained by reacting bisphenol F-type epoxy resins with epichlorohydrin to modify them to have three or more functional groups; biphenol-type epoxy resins such as biphenol-type epoxy resins and tetramethylbiphenol-type epoxy resins; novolac-type epoxy resins such as phenol novolac-type epoxy resins, cresol novolac-type epoxy resins, bisphenol A-type novolac-type epoxy resins, and alkylphenol novolac-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, naphtholaralkyl-type epoxy resins, biphenol-type epoxy resins, and the like. Epoxy resins with a naphthalene skeleton (epoxy resins containing a naphthalene skeleton), such as naphthol-type epoxy resins, naphthylene ether-type epoxy resins, naphthol novolac-type epoxy resins, and naphthalene-type epoxy resins obtained by the condensation reaction of polyhydroxynaphthalene with aldehydes; aralkyl-type epoxy resins; bixylenol-type epoxy resins; dicyclopentadiene-type epoxy resins; trisphenol-type epoxy resins; tert-butyl-catechol-type epoxy resins; and epoxy resins containing a condensed ring skeleton, such as anthracene-type epoxy resins; glycerin Diglycidylamine-type epoxy resins;Glycidyl ester-type epoxy resins;Biphenyl-type epoxy resins;Linear aliphatic epoxy resins;Epoxy resins containing butadiene structures;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 acrylic esters;Fluorene-type epoxy resins;Halogenated epoxy resins;Epoxy resins having a cardo structure are also included.

[0025] From the viewpoint of achieving the effects of the present invention more significantly, the epoxy resin used to produce the epoxy (meth)acrylate resin is preferably an epoxy resin containing an aromatic skeleton. Here, the term "aromatic skeleton" encompasses polycyclic aromatics and aromatic heterocycles. Among these, the epoxy resin used to produce the epoxy (meth)acrylate resin is preferably any of an aralkyl epoxy resin, a naphthol aralkyl epoxy resin, and an epoxy resin having a cardo structure, with a naphthol aralkyl epoxy resin being more preferred. A cardo structure refers to a structure in which two aromatic rings are bonded to a carbon atom within the ring.

[0026] In one embodiment, the acid-modified epoxy(meth)acrylate resin preferably includes an acid-modified epoxy(meth)acrylate resin having a skeleton selected from an aralkyl skeleton, a naphthol aralkyl skeleton, and a cardo skeleton, and particularly preferably includes an acid-modified epoxy(meth)acrylate resin having a naphthol aralkyl skeleton.

[0027] 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 a hydroxyl group of an epoxy(meth)acrylate resin has been esterified (hereinafter referred to as an "ester-type acid-modified epoxy(meth)acrylate resin"), and an acid-modified epoxy(meth)acrylate resin in which a hydroxyl group of an epoxy(meth)acrylate resin has been urethanized (hereinafter referred to as a "urethane-type acid-modified epoxy(meth)acrylate resin"), and particularly preferably contains an ester-type acid-modified epoxy(meth)acrylate resin.

[0028] The ester-type acid-modified epoxy(meth)acrylate resin can be produced, for example, by reacting an epoxy(meth)acrylate resin with an acid anhydride. The ester-type acid-modified epoxy(meth)acrylate resin may be used alone or in combination of two or more.

[0029] Examples of acid anhydrides include maleic anhydride, succinic anhydride, itaconic anhydride, phthalic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, trimellitic anhydride, pyromellitic anhydride, and benzophenonetetracarboxylic dianhydride, and these may be used alone or in combination of two or more. Among these, succinic anhydride and tetrahydrophthalic anhydride are preferred, and tetrahydrophthalic anhydride is more preferred.

[0030] The ester-type acid-modified epoxy(meth)acrylate resin preferably contains a resin selected from a cresol novolac skeleton-containing ester-type acid-modified epoxy(meth)acrylate resin, a bisphenol A skeleton-containing ester-type acid-modified epoxy(meth)acrylate resin, a bisphenol F skeleton-containing ester-type acid-modified epoxy(meth)acrylate resin, a biphenyl skeleton-containing acid ester-type modified epoxy(meth)acrylate resin, and a naphthol aralkyl skeleton-containing ester-type acid-modified epoxy(meth)acrylate resin.

[0031] The ester-type acid-modified epoxy (meth)acrylate resin can be synthesized by a known method, but commercially available products may also be used. Specific examples of commercially available products include "CCR-1373H" (cresol novolac skeleton-containing acid-modified epoxy acrylate resin), "ZCR-8001H" (biphenyl skeleton-containing acid-modified epoxy acrylate resin), "ZCR-1569H" (biphenyl skeleton-containing acid-modified epoxy acrylate resin), "CCR-1171H" (cresol novolac skeleton-containing acid-modified epoxy acrylate resin), "ZCR-1797H", and "ZCR-1761H" (biphenyl skeleton-containing acid-modified epoxy acrylate resin), all of which are manufactured by Nippon Kayaku Co., Ltd. Examples of suitable epoxy acrylate resins include "ZAR-2000" (bisphenol A skeleton-containing acid-modified epoxy acrylate resin), "ZFR-1491H" and "ZFR-1533H" (bisphenol F skeleton-containing acid-modified epoxy acrylate resin) manufactured by Nippon Kayaku Co., Ltd., "PR-300CP" (cresol novolac type acid-modified epoxy acrylate resin) manufactured by Showa Denko K.K., and "CCR-1179" (cresol novolac skeleton-containing epoxy acrylate resin) manufactured by Nippon Kayaku Co., Ltd.

[0032] 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 carboxyl group-containing diol compound. The urethane-type acid-modified epoxy(meth)acrylate resin may be used alone or in combination of two or more.

[0033] Examples of diisocyanate compounds include aromatic diisocyanate compounds such as phenylene diisocyanate, tolylene diisocyanate, xylylene diisocyanate, tetramethylxylylene diisocyanate, diphenyl diisocyanate, and naphthalene diisocyanate; and aliphatic diisocyanate compounds such as hexamethylene diisocyanate, dicyclohexylmethane diisocyanate, isophorone diisocyanate, allylene sulfone ether diisocyanate, allyl diisocyanate, N-acyl diisocyanate, trimethylhexamethylene diisocyanate, and 1,3-bis(isocyanatemethyl)cyclohexane.

[0034] Examples of the carboxy group-containing diol compound include dimethylolpropionic acid, dimethylolbutanoic acid, and dimethylolnonanoic acid.

[0035] The urethane-type acid-modified epoxy(meth)acrylate resin preferably contains a resin selected from a cresol novolac skeleton-containing urethane-type acid-modified epoxy(meth)acrylate resin, a bisphenol A skeleton-containing urethane-type acid-modified epoxy(meth)acrylate resin, a bisphenol F skeleton-containing urethane-type acid-modified epoxy(meth)acrylate resin, a biphenyl skeleton-containing acid-urethane-type modified epoxy(meth)acrylate resin, and a naphthol aralkyl skeleton-containing urethane-type acid-modified epoxy(meth)acrylate resin.

[0036] The urethane-type acid-modified epoxy (meth)acrylate resin can be synthesized by a known synthesis method, but a commercially available product may also be used. Examples of known synthesis methods include the method described in JP 2016-199719 A. Specific examples of commercially available products include "UXE-3024," "UXE-3011," "UXE-3012," and "UXE-3024" manufactured by Nippon Kayaku Co., Ltd.

[0037] Another embodiment of component (A) is an unsaturated modified (meth)acrylic resin obtained by reacting an ethylenically unsaturated group-containing epoxy compound with a (meth)acrylic resin having structural units obtained by polymerizing acrylic acid and / or methacrylic acid to introduce an ethylenically unsaturated group. Examples of ethylenically unsaturated group-containing epoxy compounds include glycidyl methacrylate, 4-hydroxybutyl (meth)acrylate glycidyl ether, and 3,4-epoxycyclohexylmethyl (meth)acrylate. Furthermore, it is also possible to react an acid anhydride with the hydroxyl group generated during the introduction of the unsaturated group. The acid anhydride may be the same as the acid anhydride described above. The term "(meth)acrylic resin" encompasses methacrylic resins, acrylic resins, and combinations thereof.

[0038] Such unsaturated modified (meth)acrylic resins can be commercially available products, and specific examples include "SPC-1000" and "SPC-3000" manufactured by Showa Denko K.K., and "Cyclomer P(ACA)Z-250," "Cyclomer P(ACA)Z-251," "Cyclomer P(ACA)Z-254," "Cyclomer P(ACA)Z-300," and "Cyclomer P(ACA)Z-320" manufactured by Daicel-Allnex Corporation.

[0039] From the viewpoint of improving the alkaline developability of the resin composition, the acid value of component (A) is preferably 0.1 mgKOH / g or more, more preferably 0.5 mgKOH / g or more, even more preferably 1 mgKOH / g or more, 10 mgKOH / g or more, still 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 component (A) is preferably 200 mgKOH / g or less, more preferably 150 mgKOH / g or less, even more preferably 120 mgKOH / g or less, particularly preferably 100 mgKOH / g or less.

[0040] The weight average molecular weight of component (A) is preferably 20,000 or less, more preferably 17,000 or less, even more preferably 15,000 or less, and is preferably 500 or more, more preferably 750 or more, even more preferably 900 or more. The weight average molecular weight is the weight average molecular weight in terms of polystyrene measured by gel permeation chromatography (GPC).

[0041] The content of component (A) in the core resin composition is preferably 10% by mass or more, more preferably 15% by mass or more, even more preferably 20% by mass or more, and preferably 40% by mass or less, even more preferably 35% by mass or less, and particularly preferably 30% by mass or less, from the viewpoint of improving developability, assuming that the non-volatile components of the core resin composition are 100% by mass.

[0042] The content of component (A) in the cladding resin composition is preferably 10% by mass or more, more preferably 15% by mass or more, even more preferably 20% by mass or more, and preferably 40% by mass or less, even more preferably 35% by mass or less, and particularly preferably 30% by mass or less, from the viewpoint of improving developability, assuming that the non-volatile components of the cladding resin composition are 100% by mass.

[0043] In the present invention, the content of each component in the core resin composition is a value when the nonvolatile components in the core resin composition are taken as 100% by mass, unless otherwise specified, and the content of each component in the clad resin composition is a value when the nonvolatile components in the clad resin composition are taken as 100% by mass, unless otherwise specified. The nonvolatile components refer to all nonvolatile components in the resin composition excluding the solvent.

[0044] <(B) Epoxy resin> The resin composition contains an epoxy resin as component (B). This epoxy resin (B) as component (B) does not include those corresponding to the above-mentioned component (A). By including component (B), it is possible to improve insulation reliability. The epoxy resin (B) may be used alone or in combination of two or more types.

[0045] (B) Epoxy resins include, for example, bixylenol-type epoxy resins; bisphenol-type epoxy resins such as bisphenol A-type epoxy resins, bisphenol F-type epoxy resins, bisphenol S-type epoxy resins, and bisphenol AF-type epoxy resins; dicyclopentadiene-type epoxy resins; novolac-type epoxy resins such as trisphenol-type epoxy resins and phenol novolac-type epoxy resins; tert-butyl-catechol-type epoxy resins; naphthalene-type epoxy resins, naphthol-type epoxy resins, naphthol aralkyl-type epoxy resins, naphthylene ether-type epoxy resins, and naphthol novolac-type epoxy resins. Examples of epoxy resins include epoxy resins containing an amine skeleton, anthracene-type epoxy resins, glycidylamine-type epoxy resins, glycidyl ester-type epoxy resins, cresol novolac-type epoxy resins, phenol aralkyl-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, cyclohexane-type epoxy resins, cyclohexanedimethanol-type epoxy resins, trimethylol-type epoxy resins, tetraphenylethane-type epoxy resins, isocyanurate-type epoxy resins, and phenolphthalimidine-type epoxy resins. Among these, the epoxy resin (B) preferably contains either a naphthalene-type epoxy resin or a naphthol aralkyl-type epoxy resin, from the viewpoint of achieving the effects of the present invention more significantly.

[0046] The resin composition preferably contains, as the (B) epoxy resin, an epoxy resin having two or more epoxy groups per molecule. The proportion of the epoxy resin having two or more epoxy groups per molecule relative to 100% by mass of the (B) epoxy resin is preferably 50% by mass or more, more preferably 60% by mass or more, and particularly preferably 70% by mass or more.

[0047] (B) Epoxy resins include epoxy resins that are solid at a temperature of 20°C (hereinafter sometimes referred to as "solid epoxy resins") and epoxy resins that are liquid at a temperature of 20°C (hereinafter sometimes referred to as "liquid epoxy resins"). The resin composition may contain only a liquid epoxy resin as (B) 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 that the resin composition contain only a solid epoxy resin.

[0048] As the solid epoxy resin, a solid epoxy resin having three or more epoxy groups in one molecule is preferred, and an aromatic solid epoxy resin having three or more epoxy groups in one molecule is more preferred.

[0049] Preferred solid epoxy resins include bixylenol-type epoxy resins, naphthalene-type epoxy resins, naphthol aralkyl-type epoxy resins, naphthalene-type tetrafunctional epoxy resins, naphthol novolac-type epoxy resins, cresol novolac-type epoxy resins, dicyclopentadiene-type epoxy resins, trisphenol-type epoxy resins, naphthol-type epoxy resins, biphenyl-type epoxy resins, naphthylene ether-type epoxy resins, anthracene-type epoxy resins, bisphenol A-type epoxy resins, bisphenol AF-type epoxy resins, phenol aralkyl-type epoxy resins, tetraphenylethane-type epoxy resins, and phenolphthalimidine-type epoxy resins, and it is preferable to contain either a naphthalene-type epoxy resin or a naphthol aralkyl-type epoxy resin.

[0050] Specific examples of solid epoxy resins include "HP4032H" (naphthalene type epoxy resin) manufactured by DIC Corporation; "HP-4700" and "HP-4710" (naphthalene type tetrafunctional epoxy resins) manufactured by DIC Corporation; "N-690" (cresol novolac type epoxy resin) manufactured by DIC Corporation; "N-695" (cresol novolac type epoxy resin) manufactured by DIC Corporation; "N-673" (cresol novolac type epoxy resin) manufactured by DIC Corporation; and "HP-7200", "HP-7200HH", "HP-7200H", and "HP-7200L" manufactured by DIC Corporation. (Dicyclopentadiene type epoxy resin); DIC Corporation's "EXA-7311", "EXA-7311-G3", "EXA-7311-G4", "EXA-7311-G4S", and "HP6000" (naphthylene ether type epoxy resin); Nippon Kayaku Co., Ltd.'s "EPPN-502H" (trisphenol type epoxy resin); Nippon Kayaku Co., Ltd.'s "NC7000L" (naphthol novolac type epoxy resin); Nippon Kayaku Co., Ltd.'s "NC3000H", "NC3000", "NC3000L", "NC3000FH", and "NC3100" (biphenyl type epoxy resin). type epoxy resin); "ESN475V" and "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", and "YL7890" (bixylenol type epoxy resin) manufactured by Mitsubishi Chemical Co., Ltd.; "YL6121" (biphenyl type epoxy resin) manufactured by Mitsubishi Chemical Co., Ltd.; "YX8800" (anthracene-type epoxy resin) manufactured by Mitsubishi Chemical Corporation; "YX7700" (phenol aralkyl-type epoxy resin) manufactured by Mitsubishi Chemical Corporation; "PG-100" and "CG-500" manufactured by Osaka Gas Chemicals Co., Ltd.; "YL7760" (bisphenol AF-type epoxy resin) manufactured by Mitsubishi Chemical Corporation; "YL7800" (fluorene-type epoxy resin) manufactured by Mitsubishi Chemical Corporation; "jER1010" (bisphenol A-type epoxy resin) manufactured by Mitsubishi Chemical Corporation; "jER1031S" (tetraphenylethane-type epoxy resin) manufactured by Mitsubishi Chemical Corporation;Examples include "WHR991S" (phenolphthalimidine type epoxy resin) manufactured by Nippon Kayaku Co., Ltd. These may be used alone or in combination of two or more.

[0051] The liquid epoxy resin is preferably a liquid epoxy resin having two or more epoxy groups in one molecule.

[0052] Preferred liquid epoxy resins include glycerol-type epoxy resins, bisphenol A-type epoxy resins, bisphenol F-type epoxy resins, bisphenol AF-type epoxy resins, naphthalene-type epoxy resins, glycidyl ester-type epoxy resins, glycidyl amine-type epoxy resins, phenol novolac-type epoxy resins, alicyclic epoxy resins having an ester skeleton, cyclohexanedimethanol-type epoxy resins, alicyclic glycidyl ethers, and epoxy resins having a butadiene structure.

[0053] Specific examples of liquid epoxy resins include "EX-992L" manufactured by Nagase ChemteX Corporation, "YX7400" manufactured by Mitsubishi Chemical Corporation, "HP4032", "HP4032D", and "HP4032SS" (naphthalene-type epoxy resins) manufactured by DIC Corporation; "828US", "jER828EL", "828EL", "825", and "Epikote 828EL" (bisphenol A-type epoxy resins) manufactured by Mitsubishi Chemical Corporation; and "jER807" and "1750" ( Bisphenol F epoxy resin; Mitsubishi Chemical Corporation's "jER152" (phenol novolac epoxy resin); Mitsubishi Chemical Corporation's "630", "630LSD", and "604" (glycidylamine epoxy resin); ADEKA Corporation's "ED-523T" (glycirol epoxy resin); ADEKA Corporation's "EP-3950L" and "EP-3980S" (glycidylamine epoxy resin); ADEKA Corporation's "EP-4088S" (dicyclopentadiene epoxy resin); Nippon Steel Chemical & Material Corporation's "ZX1059" (mixture of bisphenol A and bisphenol F epoxy resins); Nagase ChemteX Corporation's "EX-721" (glycidyl ester epoxy resin); Nagase ChemteX Corporation's "EX-991L" (epoxy resin containing alkyleneoxy and butadiene skeletons); Daicel Corporation's "Celloxide 2021P" (alicyclic epoxy resin with ester skeleton) ); "PB-3600" manufactured by Daicel Corporation, "JP-100" and "JP-200" manufactured by Nippon Soda Co., Ltd. (epoxy resins having a butadiene structure); "ZX1658" and "ZX1658GS" (liquid 1,4-glycidylcyclohexane type epoxy resins) manufactured by Nippon Steel Chemical & Material Co., Ltd.; "EG-280" (fluorene structure-containing epoxy resin) manufactured by Osaka Gas Chemicals Co., Ltd.; and "EX-201" (cyclic aliphatic glycidyl ether) manufactured by Nagase ChemteX Corporation.

[0054] When a solid epoxy resin and a liquid epoxy resin are used in combination as the (B) epoxy resin, the mass ratio thereof (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.

[0055] The epoxy equivalent of the (B) epoxy resin is preferably 50 g / eq. to 5,000 g / eq., more preferably 60 g / eq. to 2,000 g / eq., even more preferably 70 g / eq. to 1,000 g / eq., and even more preferably 80 g / eq. to 500 g / eq. The epoxy equivalent is the mass of the resin per equivalent of epoxy groups. This epoxy equivalent can be measured according to JIS K7236.

[0056] The weight average molecular weight (Mw) of the (B) epoxy resin is preferably 100 to 5,000, more preferably 250 to 3,000, and even more preferably 400 to 1,500. The weight average molecular weight of the resin can be measured by gel permeation chromatography (GPC) as a polystyrene-equivalent value.

[0057] The content of the (B) epoxy resin in the core resin composition is preferably 20% by mass or more, more preferably 25% by mass or more, and even more preferably 30% by mass or more, and is preferably 50% by mass or less, more preferably 45% by mass or less, and even more preferably 40% by mass or less, from the viewpoint of significantly obtaining the effects of the present invention, assuming that the non-volatile components of the core resin composition are 100% by mass.

[0058] The content of the (B) epoxy resin in the cladding resin composition is preferably 20% by mass or more, more preferably 25% by mass or more, and even more preferably 30% by mass or more, and is preferably 50% by mass or less, more preferably 45% by mass or less, and even more preferably 40% by mass or less, from the viewpoint of significantly obtaining the effects of the present invention, assuming the non-volatile components of the cladding resin composition to be 100% by mass.

[0059] The content of component (A) when the nonvolatile components of the core resin composition are 100% by mass is defined as A core The content of component (B) when the nonvolatile components of the core resin composition are taken as 100% by mass is defined as B core When A core / B coreFrom the viewpoint of significantly obtaining the effects of the present invention, is preferably 0.3 or more, more preferably 0.5 or more, even more preferably 1 or more, and is preferably 5 or less, more preferably 3 or less, even more preferably 2 or less.

[0060] The content of component (A) when the nonvolatile components of the cladding resin composition are 100% by mass is defined as A clad The content of component (B) when the nonvolatile components of the cladding resin composition are taken as 100% by mass is defined as B clad When A clad / B clad From the viewpoint of significantly obtaining the effects of the present invention, is preferably 0.3 or more, more preferably 0.5 or more, even more preferably 1 or more, and is preferably 5 or less, more preferably 3 or less, even more preferably 2 or less.

[0061] <(C) Photocurable resin> The resin composition contains a (C) photocurable resin as component (C). This (C) photocurable resin as component (C) does not include those corresponding to the above-mentioned components (A) and (B). By including component (C) in the resin composition, photoreactivity during exposure can be improved. One type of component (C) may be used alone, or two or more types may be used in combination.

[0062] As the component (C), for example, a (meth)acrylate compound having one or more (preferably two or more) (meth)acryloyl groups in one molecule can be used.

[0063] Examples of the (meth)acrylate compound include hydroxyalkyl acrylates such as 2-hydroxyethyl acrylate and 2-hydroxybutyl acrylate; mono- or diacrylates of glycols such as ethylene glycol, methoxytetraethylene glycol, polyethylene glycol, and propylene glycol; acrylamides such as N,N-dimethylacrylamide and N-methylolacrylamide; aminoalkyl acrylates such as N,N-dimethylaminoethyl acrylate; polyhydric acrylates of polyhydric alcohols such as trimethylolpropane, pentaerythritol, and dipentaerythritol, or their adducts with ethylene oxide, propylene oxide, or ε-caprolactone; acrylates of phenols such as phenoxy acrylate and phenoxyethyl acrylate, or their ethylene oxide or propylene oxide adducts; epoxy acrylates derived from glycidyl ethers such as trimethylolpropane triglycidyl ether; modified epoxy acrylates; melamine acrylates; and / or methacrylates corresponding to the above acrylates.Among these, polyhydric acrylates or polyhydric methacrylates are preferred, and for example, trihydric acrylates or methacrylates include trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, trimethylolpropane EO-adduct tri(meth)acrylate, glycerin PO-adduct tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, tetrafurfuryl alcohol oligo(meth)acrylate, ethyl carbitol oligo(meth)acrylate, 1,4-butanediol oligo(meth)acrylate, 1,6-hexanediol oligo(meth)acrylate, trimethylolpropane oligo(meth)acrylate, pentaerythritol oligo(meth)acrylate, tetramethylolmethane tetra(meth)acrylate, and dipentaerythritol. Examples of the photosensitive (meth)acrylate compounds include hexa(meth)acrylate and (meth)acrylic acid esters of N,N,N',N'-tetrakis(β-hydroxyethyl)ethyldiamine. Examples of the trivalent or higher acrylates or methacrylates include phosphate triester (meth)acrylates such as tri(2-(meth)acryloyloxyethyl)phosphate, tri(2-(meth)acryloyloxypropyl)phosphate, tri(3-(meth)acryloyloxypropyl)phosphate, tri(3-(meth)acryloyl-2-hydroxyloxypropyl)phosphate, di(3-(meth)acryloyl-2-hydroxyloxypropyl)(2-(meth)acryloyloxyethyl)phosphate, and (3-(meth)acryloyl-2-hydroxyloxypropyl)di(2-(meth)acryloyloxyethyl)phosphate. These photosensitive (meth)acrylate compounds may be used alone or in combination of two or more. "EO" refers to ethylene oxide.

[0064] Component (C) can be a commercially available product, such as "DPHA" manufactured by Nippon Kayaku Co., Ltd. or "EBECRYL3708" manufactured by Daicel Allnex Co., Ltd.

[0065] Component (C) typically has a low viscosity. The specific viscosity of component (C) is typically less than 0.5 Pa s. There is no particular lower limit to the viscosity of component (C), and it can be, for example, 0.001 Pa s or more, 0.005 Pa s or more, or 0.01 Pa s or more. The viscosity of component (C) can be measured using an E-type viscometer at 25±2°C.

[0066] The content of component (C) in the core resin composition is preferably 15% by mass or more, more preferably 20% by mass or more, and even more preferably 25% by mass or more, and is preferably 40% by mass or less, more preferably 35% by mass or less, and even more preferably 30% by mass or less, from the viewpoint of promoting photocuring, assuming that the non-volatile components in the core resin composition are 100% by mass.

[0067] The content of component (C) in the cladding resin composition is preferably 15% by mass or more, more preferably 20% by mass or more, and even more preferably 25% by mass or more, and is preferably 50% by mass or less, more preferably 45% by mass or less, and even more preferably 40% by mass or less, from the viewpoint of promoting photocuring, assuming that the non-volatile components in the cladding resin composition are 100% by mass.

[0068] The content of component (C) when the nonvolatile components of the core resin composition are taken as 100% by mass is C core When A core / C core From the viewpoint of significantly obtaining the effects of the present invention, is preferably 0.1 or more, more preferably 0.3 or more, even more preferably 0.5 or more, and is preferably 3 or less, more preferably 2 or less, even more preferably 1.5 or less.

[0069] The content of component (C) when the nonvolatile components of the cladding resin composition are taken as 100% by mass is C clad When A clad / C clad From the viewpoint of significantly obtaining the effects of the present invention, is preferably 0.1 or more, more preferably 0.3 or more, even more preferably 0.5 or more, and is preferably 3 or less, more preferably 2 or less, even more preferably 1.5 or less.

[0070] C clad / C core From the viewpoint of significantly obtaining the effects of the present invention, C is preferably 0.1 or more, more preferably 0.3 or more, even more preferably 0.5 or more, or 0.8 or more, and is preferably 3 or less, more preferably 2 or less, even more preferably 1.5 or less. clad / C core By adjusting the content of component (C) in the core and clad resin compositions so that the shrinkage rate falls within this range, it is possible to suppress changes in the shrinkage rate, and as a result, to suppress decreases in optical transmission loss.

[0071] <(D) Photopolymerization initiator> The resin composition contains a photopolymerization initiator as component (D). This photopolymerization initiator (D) as component (D) does not include those corresponding to the above-mentioned components (A) to (C). By including the photopolymerization initiator (D) in the resin composition, the resin composition can be efficiently photocured. The component (D) may be used alone or in combination of two or more.

[0072] Any compound can be used as the (D) photopolymerization initiator. Examples of such compounds include acylphosphine oxide photopolymerization initiators such as bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide and 2,4,6-trimethylbenzoyldiphenylphosphine oxide; oxime ester photopolymerization initiators such as 1,2-octanedione, 1-4-(phenylthio)-2-(O-benzoyloxime), ethanone, 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazol-3-yl]-, 1-(O-acetyloxime); 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-1-butanone, 2-(dimethylamino)-2-[(4-methylphenyl)methyl]-[4-(4-morpholinyl)phenyl]-1-butanone, and 2-methyl-1-[4-(methyl Examples of photopolymerization initiators include α-aminoalkylphenone-based photopolymerization initiators such as α-(4-(2-hydroxyethoxy)phenyl)-2-morpholinopropan-1-one; benzophenone, methylbenzophenone, o-benzoylbenzoic acid, benzoyl ethyl ether, 2,2-diethoxyacetophenone, 2,4-diethylthioxanthone, diphenyl-(2,4,6-trimethylbenzoyl)phosphine oxide, ethyl-(2,4,6-trimethylbenzoyl)phenylphosphinate, 4,4'-bis(diethylamino)benzophenone, 1-hydroxy-cyclohexyl-phenyl ketone, 2,2-dimethoxy-1,2-diphenylethan-1-one, and 1-[4-(2-hydroxyethoxy)phenyl]-2-hydroxy-2-methyl-1-propan-1-one. Sulfonium salt-based photopolymerization initiators can also be used. These may be used alone or in combination. Among these, from the viewpoint of more efficiently photocuring the resin composition, either an acylphosphine oxide-based photopolymerization initiator or an oxime ester-based photopolymerization initiator is preferred, and an acylphosphine oxide-based photopolymerization initiator is more preferred.

[0073] Specific examples of the (D) photopolymerization initiator include "Omnirad907," "Omnirad369," "Omnirad379," "Omnirad819," and "OmniradTPO" manufactured by IGM Resins; "IrgacureOXE-01," "IrgacureOXE-02," "IrgacureTPO," and "Irgacure819" manufactured by BASF; and "N-1919" manufactured by ADEKA Corporation.

[0074] The content of the (D) photopolymerization initiator in the core resin composition is preferably 1% by mass or more, more preferably 1.5% by mass or more, and even more preferably 2% by mass or more, based on 100% by mass of the nonvolatile components of the core resin composition, from the viewpoint of sufficiently photocuring the core resin composition. On the other hand, from the viewpoint of suppressing deterioration in developability due to excessive sensitivity, the upper limit is preferably 10% by mass or less, more preferably 8% by mass or less, and even more preferably 5% by mass or less.

[0075] The content of the photopolymerization initiator (D) in the cladding resin composition is preferably 1% by mass or more, more preferably 1.5% by mass or more, and even more preferably 2% by mass or more, based on 100% by mass of the nonvolatile components of the cladding resin composition, from the viewpoint of sufficiently photocuring the cladding resin composition. On the other hand, from the viewpoint of suppressing deterioration of developability due to excessive sensitivity, the upper limit is preferably 10% by mass or less, more preferably 8% by mass or less, and even more preferably 5% by mass or less.

[0076] The content of component (D) when the nonvolatile components of the core resin composition are taken as 100% by mass is defined as D core When A core / D core From the viewpoint of significantly obtaining the effects of the present invention, is preferably 3 or more, more preferably 5 or more, even more preferably 8 or more, and is preferably 20 or less, more preferably 15 or less, even more preferably 13 or less.

[0077] The content of component (D) when the nonvolatile components of the cladding resin composition are taken as 100% by mass is defined as D clad When Aclad / D clad From the viewpoint of significantly obtaining the effects of the present invention, is preferably 3 or more, more preferably 5 or more, even more preferably 8 or more, and is preferably 20 or less, more preferably 15 or less, even more preferably 13 or less.

[0078] The resin composition may further contain, in combination with component (D), a tertiary amine such as N,N-dimethylaminobenzoic acid ethyl ester, N,N-dimethylaminobenzoic acid isoamyl ester, pentyl-4-dimethylaminobenzoate, triethylamine, triethanolamine, etc. as a photopolymerization initiation aid, or may contain a photosensitizer such as pyrarizones, anthracenes, coumarins, xanthones, thioxanthones, etc. These may be used alone or in combination of two or more.

[0079] <(E) One or more flame retardants selected from phosphate ester compounds and phosphazene compounds> The resin composition contains, as component (E), one or more flame retardants selected from (E) phosphate ester compounds and phosphazene compounds. The one or more flame retardants selected from (E) phosphate ester compounds and phosphazene compounds as component (E) do not include those corresponding to the above-mentioned components (A) to (D). By including component (E) in the resin composition, it is possible to improve flame retardancy, maintain a single mode, and effectively suppress optical transmission loss in the optical waveguide.

[0080] From the viewpoint of improving flame retardancy, the content of phosphorus atoms in the resin composition is preferably 0.01% by mass or more, more preferably 0.02% by mass or more, even more preferably 0.03% by mass or more, 0.05% by mass or more, or 0.1% by mass or more, based on 100% by mass of the non-volatile components in the resin composition. The upper limit is preferably 10% by mass or less, more preferably 5% by mass or less, even more preferably 3% by mass or less, 1% by mass or less, 0.8% by mass or less, or 0.5% by mass or less. Here, the content of phosphorus atoms refers to the concept of including not only the phosphorus atoms contained in component (E) but also the content of phosphorus atoms contained in components (A) to (H) excluding component (C).

[0081] Component (E) includes either a phosphate ester compound or a phosphazene compound. Examples of the phosphate ester compound include compounds represented by the following formula (E-1): compounds represented by the following formula (E-2): non-halogenated aliphatic phosphate esters such as trimethyl phosphate, triethyl phosphate, tributyl phosphate, and trioctyl phosphate; trixylenyl phosphate, triphenyl phosphate, cresyl diphenyl phosphate, dicresyl phenyl phosphate, tricresyl phosphate, cresyl di-2,6-xylenylphenyl phosphate, tris(2,6-dimethylphenyl)phosphate, tris(4-isopropylphenyl)phosphate, tris(4-tert-butylphenyl)phosphate, and bis(4-tert-butylphenyl). non-halogenated aromatic phosphate esters such as tris(1-chloro-2-propyl)phosphate, tris(1,3-dichloro-2-propyl)phosphate, tris[3-bromo-2,2-bis(bromomethyl)propyl]phosphate; and (meth)acrylic phosphate esters such as 2-methacryloyloxyethyl acid phosphate and diphenyl-2-methacryloyloxyethyl phosphate.

[0082] Among these, from the viewpoint of significantly achieving the effects of the present invention, it is preferable that the phosphate ester compound contains either a compound represented by formula (E-1) or a compound represented by formula (E-2). [ka] In formula (E-1), R 1 ~R 20 each independently represents a hydrogen atom, a hydroxy group, or an alkyl group having 1 to 6 carbon atoms which may have a substituent; W 1 represents a group represented by formula (E-1a) or a group represented by formula (E-1b). In formula (E-1b), R represents an oxygen atom or a divalent hydrocarbon group having 1 to 20 carbon atoms which may have a substituent. In formula (E-2), R 21 ~R 28 each independently represents a hydrogen atom, a hydroxy group, or an alkyl group having 1 to 6 carbon atoms which may have a substituent; R 29 represents a (meth)acryloyl group, an oxygen atom, a divalent hydrocarbon group of 1 to 10 carbon atoms which may have a substituent, a monovalent hydrocarbon group of 1 to 20 carbon atoms which may have a substituent, or a monovalent group consisting of a combination thereof.

[0083] In formula (E-1), R 1 ~R 20 each independently represents a hydrogen atom, a hydroxy group, or an alkyl group having 1 to 6 carbon atoms which may have a substituent. The number of carbon atoms in the substituent is not included in the number of carbon atoms. The alkyl group having 1 to 6 carbon atoms may be linear, branched, or cyclic. The alkyl group having 1 to 6 carbon atoms is preferably an alkyl group having 1 to 3 carbon atoms, and more preferably an alkyl group having 1 or 2 carbon atoms. Examples of the alkyl group having 1 to 6 carbon atoms include a methyl group, an ethyl group, an n-propyl group, an i-propyl group, an n-butyl group, a t-butyl group, a pentyl group, and a hexyl group.

[0084] R 1~R 20 The alkyl group having 1 to 6 carbon atoms represented by may or may not have a substituent. The substituent is not particularly limited. For example, a halogen atom, a hydroxy group, -O-C 1-6 alkyl group, -N(C 1-10 alkyl group)2, C 1-10 alkyl group, C 6-10 aryl group, -NH2, -CN, -C(O)O-C 1-10 alkyl group, -COOH, -C(O)H, -NO2, etc. Here, the term "C p-q "(p and q are positive integers and satisfy p < q.) represents that the number of carbon atoms of the organic group described immediately after this term is p to q. For example, the expression "C 1-10 alkyl group" indicates an alkyl group having 1 to 10 carbon atoms. These substituents may be bonded to each other to form a ring, and the ring structure includes a spiro ring and a condensed ring.

[0085] The above-mentioned substituents may further have a substituent (hereinafter sometimes referred to as a "secondary substituent"). Unless otherwise specified, the same substituents as those described above may be used as the secondary substituent.

[0086] In formula (E-1), R 1 , R 5 , R 6 , R 10 , R 11 , R 15 , R 16 , and R 20 preferably represent an alkyl group having 1 to 6 carbon atoms which may or may not have a substituent, and R 2 ~R 4 , R 7 ~R​​​​​​​​​​​​​​​represents a group represented by formula (E-1a) or a group represented by formula (E-1b). Examples of the group represented by formula (E-1a) include the groups represented by the following (E-1a-1) to (E-1a-3), with the group represented by formula (E-1a-3) being preferred. In the formula, * represents a bond. [ka]

[0088] In formula (E-1b), R represents an oxygen atom or a divalent hydrocarbon group of 1 to 20 carbon atoms which may have a substituent. The number of carbon atoms does not include the number of carbon atoms of the substituent. The divalent hydrocarbon group of 1 to 20 carbon atoms which may have a substituent represented by R preferably has 1 to 10 carbon atoms, more preferably 1 to 8 carbon atoms, and even more preferably 1 to 6 carbon atoms. The divalent hydrocarbon group may be linear, branched, or cyclic, with cyclic divalent hydrocarbon groups being preferred. Examples of divalent hydrocarbon groups include divalent aliphatic hydrocarbon groups and divalent aromatic hydrocarbon groups, with divalent aliphatic hydrocarbon groups being preferred. The divalent hydrocarbon group may be either a divalent saturated hydrocarbon group or a divalent unsaturated hydrocarbon group, with divalent saturated hydrocarbon groups being preferred. Specific examples of divalent hydrocarbon groups include alkylene groups, alkenylene groups, alkynylene groups, and arylene groups.

[0089] Examples of the alkylene group include ethylene, propylene, butylene, pentylene, hexylene, heptylene, octylene, nonylene, and decylene groups, as well as groups of the following formula (E-2a-1) and (E-2a-2), with the group of the following formula (E-2a-1) being preferred: In the formula, * represents a bond. [ka]

[0090] Examples of the alkenylene group include an ethenylene group, a propenylene group, a butenylene group, a pentenylene group, a hexenylene group, a heptenylene group, an octenylene group, a nonenylene group, and a decenylene group.

[0091] Examples of the alkynylene group include an ethynylene group, a propynylene group, a butynylene group, a pentynylene group, a hexynylene group, a heptynylene group, an octynylene group, a nonynylene group, and a decynylene group.

[0092] Examples of the arylene group include a phenylene group and a naphthylene group.

[0093] Among these, in formula (E-1b), R is preferably an alkylene group of 1 to 20 carbon atoms which may have a substituent, more preferably an alkylene group of 1 to 10 carbon atoms which may have a substituent, even more preferably an alkylene group of 1 to 8 carbon atoms which may have a substituent, still more preferably an alkylene group of 1 to 6 carbon atoms which may have a substituent, and a group of formula (E-2a-1) is particularly preferred.

[0094] The divalent hydrocarbon group having 1 to 20 carbon atoms represented by R may or may not have a substituent. Examples of the substituent include R in formula (E-1). 1 Among these, the substituents that the divalent hydrocarbon group having 1 to 20 carbon atoms represented by R may have are the same as those that C 1-10 An alkyl group is preferred, and a methyl group is preferred.

[0095] Examples of the group represented by formula (E-1b) include the following groups (E-1b-1) to (E-1b-6), with the group (E-1b-1) being preferred. In the formula, R is the same as R in formula (E-1b). In the formula, * represents a bond. [ka]

[0096] Examples of the compound represented by formula (E-1) include, but are not limited to, the compounds exemplified below. [ka]

[0097] In formula (E-2), R 21 ~R 28 each independently represents a hydrogen atom, a hydroxy group, or an alkyl group having 1 to 6 carbon atoms which may have a substituent, and R in formula (E-1) 1 Among them, R 21 ~R 28 preferably represents a hydrogen atom.

[0098] In formula (E-2), R 29 represents a (meth)acryloyl group, an oxygen atom, a divalent hydrocarbon group of 1 to 10 carbon atoms which may have a substituent, a monovalent hydrocarbon group of 1 to 20 carbon atoms which may have a substituent, or a monovalent group consisting of a combination thereof. The divalent hydrocarbon group of 1 to 10 carbon atoms which may have a substituent is the same as the divalent hydrocarbon group of 1 to 10 carbon atoms which may have a substituent represented by R in formula (E-1b).

[0099] The monovalent hydrocarbon group having 1 to 20 carbon atoms, which may have a substituent, preferably has 1 to 15 carbon atoms, more preferably 1 to 10 carbon atoms, and even more preferably 1 to 6 carbon atoms. The number of carbon atoms does not include the number of carbon atoms of the substituent. The monovalent hydrocarbon group may be linear, branched, or cyclic, with linear monovalent hydrocarbon groups being preferred. Examples of monovalent hydrocarbon groups include monovalent aliphatic hydrocarbon groups and monovalent aromatic hydrocarbon groups, with monovalent aromatic hydrocarbon groups being preferred. The monovalent hydrocarbon group may be either a monovalent saturated hydrocarbon group or a monovalent unsaturated hydrocarbon group, with monovalent unsaturated hydrocarbon groups being preferred. Specific examples of monovalent hydrocarbon groups include alkyl groups, alkenyl groups, alkynyl groups, and aryl groups. The substituent that the monovalent hydrocarbon group having 1 to 20 carbon atoms may have is R in formula (E-1). 1 Among these, the substituent that the monovalent hydrocarbon group having 1 to 20 carbon atoms may have is preferably a hydroxy group.

[0100] Examples of the alkyl group include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, a sec-butyl group, an isobutyl group, a tert-butyl group, and a pentyl group.

[0101] Examples of the alkenyl group include an ethynyl group, a propynyl group, a butynyl group, and a pentynyl group.

[0102] Examples of the alkynyl group include an ethynyl group, a propynyl group, a butynyl group, a sec-butynyl group, an isobutynyl group, a tert-butynyl group, and a pentynyl group.

[0103] Examples of the aryl group include a phenyl group, a naphthyl group, and a 2,5-dihydroxyphenyl group, with the 2,5-dihydroxyphenyl group being preferred.

[0104] As the monovalent group formed from these combinations, a monovalent group formed by combining a (meth)acryloyl group, an oxygen atom, and a divalent hydrocarbon group of 1 to 10 carbon atoms which may have a substituent is preferred, a monovalent group formed by combining a (meth)acryloyl group and an alkylene group of 1 to 10 carbon atoms which may have a substituent is more preferred, and a monovalent group formed by combining a (meth)acryloyl group and a methylene group is even more preferred.

[0105] R 29 is preferably a monovalent group formed by combining an aryl group or (meth)acryloyl group which may have a substituent, an oxygen atom, and a divalent hydrocarbon group of 1 to 10 carbon atoms which may have a substituent, more preferably a monovalent group formed by combining an aryl group or (meth)acryloyl group which may have a substituent, and an alkylene group of 1 to 10 carbon atoms which may have a substituent, and even more preferably a monovalent group formed by combining a 2,5-dihydroxyphenyl group, or a (meth)acryloyl group, and a methylene group.

[0106] Examples of the compound represented by formula (E-2) include, but are not limited to, the compounds exemplified below. [ka]

[0107] The phosphazene compound is not particularly limited as long as it is a cyclic compound containing nitrogen and phosphorus as constituent elements, but the phosphazene compound is preferably a phosphazene compound having a phenolic hydroxyl group.

[0108] The phosphazene compound is preferably a compound represented by the following formula (E-3). [ka] (In formula (E-3), R 31 and R 32 each independently represents a hydrogen atom, a hydroxy group, or an alkyl group having 1 to 6 carbon atoms which may have a substituent; n represents an integer of 3 to 25; and m1 and m2 each independently represent an integer of 0 to 5.

[0109] R 31 and R 32 and each independently represent a hydrogen atom, a hydroxy group, or an alkyl group having 1 to 6 carbon atoms which may have a substituent, and the alkyl group having 1 to 6 carbon atoms which may have a substituent is represented by R 1 is the same as the alkyl group having 1 to 6 carbon atoms, which may have a substituent, represented by R 31 and R 32 Preferably, each independently represents a hydrogen atom, a hydroxy group, or a methyl group.

[0110] n represents an integer of 3 to 25, preferably an integer of 3 to 15, more preferably an integer of 3 to 10, and even more preferably 3.

[0111] m1 and m2 each independently represent an integer of 0 to 5, preferably an integer of 0 to 3, and more preferably 0 or 1.

[0112] Examples of the compound represented by formula (E-3) include, but are not limited to, the compounds exemplified below: In the formula, n represents an integer of 3 to 25. [ka]

[0113] Commercially available products can be used for component (E). Examples of commercially available products include "HCA-HQ," "HCA-HQ-HS," and "HCA=NQ" manufactured by Sankosha, "SR-3000" and "PX-200" manufactured by Daihachi Industrial Chemical Co., Ltd., "SPS-100" manufactured by Otsuka Chemical Co., Ltd., "FP-100" manufactured by Fushimi Pharmaceutical Co., Ltd., "SPH-100," "SPS-100," "SPB-100," and "SPE-100" manufactured by Otsuka Chemical Co., Ltd., "FP-100," "FP-110," "FP-300," "FP-400," and "FP-390" manufactured by Fushimi Pharmaceutical Co., Ltd., and "FRM-1000" manufactured by Nippon Kayaku Co., Ltd.

[0114] The content of component (E) in the core resin composition is preferably 0.01% by mass or more, more preferably 0.05% by mass or more, and even more preferably 0.1% by mass or more, and is preferably 1% by mass or less, more preferably 0.5% by mass or less, and even more preferably 0.3% by mass or less, from the viewpoint of promoting photocuring, assuming that the non-volatile components in the core resin composition are 100% by mass.

[0115] The content of component (E) in the cladding resin composition is preferably 0.1% by mass or more, more preferably 0.3% by mass or more, and even more preferably 0.5% by mass or more, based on 100% by mass of the non-volatile components in the cladding resin composition, from the viewpoint of promoting photocuring, and is preferably 10% by mass or less, more preferably 8% by mass or less, and even more preferably 5% by mass or less, 4% by mass or less, or 3% by mass or less.

[0116] The content (mass%) of component (E) in the clad resin composition is defined as E when the nonvolatile components of the clad resin composition are taken as 100 mass%. cladThe content (mass%) of component (E) in the core resin composition is defined as E when the nonvolatile components of the core resin composition are defined as 100 mass%. core When E clad -E core is 0.6 or more, preferably 1 or more, more preferably 1.5 or more, and even more preferably 2 or more. The upper limit is 12 or less, preferably 10 or less, more preferably 5 or less, and even more preferably 4 or less, or 3 or less. E clad -E core By adjusting the content of component (E) in the core and clad resin compositions so that the content falls within this range, the change in shrinkage rate is suppressed, and as a result, it becomes possible to suppress the decrease in optical transmission loss.

[0117] A core / E core From the viewpoint of significantly obtaining the effects of the present invention, is preferably 50 or more, more preferably 100 or more, even more preferably 130 or more, and is preferably 300 or less, more preferably 250 or less, even more preferably 200 or less.

[0118] A clad / E clad From the viewpoint of significantly obtaining the effects of the present invention, is preferably 1 or more, more preferably 1.5 or more, even more preferably 2 or more, and is preferably 100 or less, more preferably 75 or less, even more preferably 50 or less.

[0119] <(F) Curing accelerator> The resin composition may contain a curing accelerator (F) as an optional component. The curing accelerator (F) as component (F) does not include components (A) to (E) described above. The curing accelerator (F) functions as a catalyst for the reaction of components such as the epoxy resin (B) contained in the resin composition, thereby accelerating the curing of the resin composition.

[0120] Examples of the curing accelerator include imidazole-based curing accelerators, phosphorus-based curing accelerators, urea-based curing accelerators, guanidine-based curing accelerators, metal-based curing accelerators, and amine-based curing accelerators. Among these, imidazole-based curing accelerators are preferred. (F) The curing accelerator may be used alone or in combination of two or more.

[0121] Examples of the imidazole curing accelerator include 2-methylimidazole, 2-undecylimidazole, 2-heptadecylimidazole, 1,2-dimethylimidazole, 2-ethyl-4-methylimidazole, 1,2-dimethylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, 1-benzyl-2-methylimidazole, and 1-benzyl-2-methylimidazole. Phenylimidazole, 1-cyanoethyl-2-methylimidazole, 1-cyanoethyl-2-undecylimidazole, 1-cyanoethyl-2-ethyl-4-methylimidazole, 1-cyanoethyl-2-phenylimidazole, 1-cyanoethyl-2-undecylimidazole, 1-cyanoethyl-2-phenylimidazolium trimellitate, 1-cyanoethyl-2-phenylimidazolium trimellitate, 2,4-diamino-6-[2'-methylimidazolyl -(1')]-ethyl-s-triazine, 2,4-diamino-6-[2'-undecylimidazolyl-(1')]-ethyl-s-triazine, 2,4-diamino-6-[2'-ethyl-4'-methylimidazolyl-(1')]-ethyl-s-triazine, 2,4-diamino-6-[2'-methylimidazolyl-(1')]-ethyl-s-triazine isocyanuric acid adduct, 2-phenylimidazole isocyanuric acid adduct Examples of imidazole compounds include 2-phenyl-4,5-dihydroxymethylimidazole, 2-phenyl-4-methyl-5-hydroxymethylimidazole, 2,3-dihydro-1H-pyrrolo[1,2-a]benzimidazole, 1-dodecyl-2-methyl-3-benzylimidazolium chloride, 2-methylimidazoline, and 2-phenylimidazoline, as well as adducts of imidazole compounds with epoxy resins. Commercially available imidazole curing accelerators include "1B2PZ," "2E4MZ," "2MZA-PW," "2MZ-OK," "2MA-OK," "2MA-OK-PW," "2PHZ," "2PHZ-PW," "Cl1Z," "Cl1Z-CN," "Cl1Z-CNS," and "C11Z-A" manufactured by Shikoku Chemicals Corporation; and "P200-H50" manufactured by Mitsubishi Chemical Corporation.

[0122] Examples of the phosphorus-based curing accelerator include aliphatic phosphonium salts such as tetrabutylphosphonium bromide, tetrabutylphosphonium chloride, tetrabutylphosphonium acetate, tetrabutylphosphonium decanoate, tetrabutylphosphonium laurate, bis(tetrabutylphosphonium)pyromellitate, tetrabutylphosphonium hydrogenhexahydrophthalate, tetrabutylphosphonium 2,6-bis[(2-hydroxy-5-methylphenyl)methyl]-4-methylphenolate, and di-tert-butyldimethylphosphonium tetraphenylborate; methyltriphenylphosphonium bromide, ethyltriphenylphosphonium bromide, propyltriphenylphosphonium bromide, butyltriphenylphosphonium bromide, benzyltriphenylphosphonium chloride, tetraphenylphosphonium bromide, p-tolyltriphenylphosphonium tetra-p-tolylborate, and tetraphenylphosphonium tetra-p-tolylborate. aromatic phosphonium salts such as tetraphenylborate, tetraphenylphosphonium tetra-p-tolylborate, triphenylethylphosphonium tetraphenylborate, tris(3-methylphenyl)ethylphosphonium tetraphenylborate, tris(2-methoxyphenyl)ethylphosphonium tetraphenylborate, (4-methylphenyl)triphenylphosphonium thiocyanate, tetraphenylphosphonium thiocyanate, and butyltriphenylphosphonium thiocyanate; aromatic phosphine-borane complexes such as triphenylphosphine-triphenylborane; aromatic phosphine-quinone adducts such as triphenylphosphine-p-benzoquinone adduct; aliphatic phosphines such as tributylphosphine, tri-tert-butylphosphine, trioctylphosphine, di-tert-butyl(2-butenyl)phosphine, di-tert-butyl(3-methyl-2-butenyl)phosphine, and tricyclohexylphosphine;Dibutylphenylphosphine, di-tert-butylphenylphosphine, methyldiphenylphosphine, ethyldiphenylphosphine, butyldiphenylphosphine, diphenylcyclohexylphosphine, triphenylphosphine, tri-o-tolylphosphine, tri-m-tolylphosphine, tri-p-tolylphosphine, tris(4-ethylphenyl)phosphine, tris(4-propylphenyl)phosphine, tris(4-isopropylphenyl)phosphine, tris(4-butylphenyl)phosphine, tris(4-tert-butylphenyl)phosphine, tris(2,4-dimethylphenyl)phosphine, tris(2,5-dimethylphenyl)phosphine, tris(2,6-dimethylphenyl)phosphine aromatic phosphines such as benzene, tris(3,5-dimethylphenyl)phosphine, tris(2,4,6-trimethylphenyl)phosphine, tris(2,6-dimethyl-4-ethoxyphenyl)phosphine, tris(2-methoxyphenyl)phosphine, tris(4-methoxyphenyl)phosphine, tris(4-ethoxyphenyl)phosphine, tris(4-tert-butoxyphenyl)phosphine, diphenyl-2-pyridylphosphine, 1,2-bis(diphenylphosphino)ethane, 1,3-bis(diphenylphosphino)propane, 1,4-bis(diphenylphosphino)butane, 1,2-bis(diphenylphosphino)acetylene, and 2,2'-bis(diphenylphosphino)diphenyl ether;

[0123] Examples of the urea-based curing accelerator include 1,1-dimethylurea; aliphatic dimethylureas such as 1,1,3-trimethylurea, 3-ethyl-1,1-dimethylurea, 3-cyclohexyl-1,1-dimethylurea, and 3-cyclooctyl-1,1-dimethylurea; 3-phenyl-1,1-dimethylurea, 3-(4-chlorophenyl)-1,1-dimethylurea, 3-(3,4-dichlorophenyl)-1,1-dimethylurea, 3-(3-chloro-4-methylphenyl)-1,1-dimethylurea, 3-(2-methylphenyl)-1,1-dimethylurea, 3-(4-methylphenyl)-1,1-dimethylurea, and 3-(3,4-dimethylphenyl)-1,1-dimethylurea. aromatic dimethylureas such as toluene bis(dimethylurea), 3-(4-isopropylphenyl)-1,1-dimethylurea, 3-(4-methoxyphenyl)-1,1-dimethylurea, 3-(4-nitrophenyl)-1,1-dimethylurea, 3-[4-(4-methoxyphenoxy)phenyl]-1,1-dimethylurea, 3-[4-(4-chlorophenoxy)phenyl]-1,1-dimethylurea, 3-[3-(trifluoromethyl)phenyl]-1,1-dimethylurea, N,N-(1,4-phenylene)bis(N',N'-dimethylurea), and N,N-(4-methyl-1,3-phenylene)bis(N',N'-dimethylurea) [toluene bisdimethylurea].

[0124] Examples of guanidine curing accelerators include dicyandiamide, 1-methylguanidine, 1-ethylguanidine, 1-cyclohexylguanidine, 1-phenylguanidine, 1-(o-tolyl)guanidine, dimethylguanidine, diphenylguanidine, trimethylguanidine, tetramethylguanidine, pentamethylguanidine, 1,5,7-triazabicyclo[4.4.0]dec-5-ene, 7-methyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene, 1-methylbiguanide, 1-ethylbiguanide, 1-n-butylbiguanide, 1-n-octadecylbiguanide, 1,1-dimethylbiguanide, 1,1-diethylbiguanide, 1-cyclohexylbiguanide, 1-allylbiguanide, 1-phenylbiguanide, and 1-(o-tolyl)biguanide.

[0125] Examples of metal-based curing accelerators include organometallic complexes or organometallic salts of metals such as cobalt, copper, zinc, iron, nickel, manganese, and tin. Specific examples of organometallic complexes include organic cobalt complexes such as cobalt(II) acetylacetonate and cobalt(III) acetylacetonate, organic copper complexes such as copper(II) acetylacetonate, organic zinc complexes such as zinc(II) acetylacetonate, organic iron complexes such as iron(III) acetylacetonate, organic nickel complexes such as nickel(II) acetylacetonate, and organic manganese complexes such as manganese(II) acetylacetonate. Examples of organometallic salts include zinc octoate, tin octoate, zinc naphthenate, cobalt naphthenate, tin stearate, and zinc stearate.

[0126] Examples of the amine curing accelerator include trialkylamines such as triethylamine and tributylamine, 4-dimethylaminopyridine, benzyldimethylamine, 2,4,6-tris(dimethylaminomethyl)phenol, 1,8-diazabicyclo(5,4,0)-undecene, etc. Commercially available amine curing accelerators may be used, such as "MY-25" manufactured by Ajinomoto Fine-Techno Co., Inc.

[0127] The content of component (F) in the core resin composition is preferably 0.1% by mass or more, more preferably 0.2% by mass or more, and even more preferably 0.3% by mass or more, and is preferably 1.5% by mass or less, more preferably 1% by mass or less, and even more preferably 0.8% by mass or less, from the viewpoint of promoting photocuring, assuming that the non-volatile components in the core resin composition are 100% by mass.

[0128] The content of component (F) in the cladding resin composition is preferably 0.1% by mass or more, more preferably 0.2% by mass or more, and even more preferably 0.3% by mass or more, and is preferably 1.5% by mass or less, more preferably 1% by mass or less, and even more preferably 0.5% by mass or less, from the viewpoint of promoting photocuring, assuming that the non-volatile components in the cladding resin composition are 100% by mass.

[0129] <(G) Solvent> The resin composition may further contain a (G) solvent as an optional component. The viscosity of the varnish can be adjusted by adding a (G) solvent. Examples of the (G) solvent include organic solvents.

[0130] Examples of (G) solvents include ketones such as ethyl methyl ketone (MEK) and cyclohexanone; aromatic hydrocarbons such as toluene, xylene, and tetramethylbenzene; glycol ethers such as diethylene glycol monoethyl ether acetate, ethyl diglycol acetate (EDGAc), 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; esters such as ethyl acetate, butyl acetate, butyl cellosolve acetate, carbitol acetate, and ethyl diglycol acetate; aliphatic hydrocarbons such as octane and decane; and petroleum-based solvents such as petroleum ether, petroleum naphtha, hydrogenated petroleum naphtha, and solvent naphtha. These solvents may be used alone or in combination. When a solvent is used, the content can be appropriately adjusted from the viewpoint of the coatability of the resin composition.

[0131] <(H) Other Additives> The resin composition may further contain (H) other additives to the extent that the object of the present invention is not impaired. Examples of (H) other additives include inorganic fillers, organic fillers, fine particles such as melamine and organic bentonite, colorants such as phthalocyanine blue, phthalocyanine green, iodine green, diazo yellow, crystal violet, titanium oxide, carbon black, and naphthalene black, polymerization inhibitors such as hydroquinone, phenothiazine, methylhydroquinone, hydroquinone monomethyl ether, catechol, and pyrogallol, thickeners such as bentone and montmorillonite, silicone-based, fluorine-based, and vinyl resin-based antifoaming agents, and thermosetting resins such as phenolic curing agents and cyanate ester-based curing agents.

[0132] The resin composition can be produced by mixing the essential components (A) to (E) and the optional components (F) to (H), and kneading or stirring the mixture, if necessary, using a kneading device such as a triple roll mill, a ball mill, a bead mill, or a sand mill, or a stirring device such as a super mixer or a planetary mixer.

[0133] <Physical properties of the photosensitive resin composition set> The refractive index of the cured product obtained by heating the core resin composition at 190°C for 90 minutes is preferably 1.3 or more, more preferably 1.4 or more, and even more preferably 1.5 or more, and is preferably 2 or less, more preferably 1.9 or less, and even more preferably 1.8 or less. The refractive index can be measured according to the method described in the examples below.

[0134] The refractive index of the cured product obtained by heating and curing the cladding resin composition at 190°C for 90 minutes is preferably 1.3 or more, more preferably 1.4 or more, and even more preferably 1.5 or more, and is preferably 2 or less, more preferably 1.9 or less, and even more preferably 1.8 or less. The refractive index can be measured according to the method described in the examples below.

[0135] The photosensitive resin composition set of the present invention has a refractive index n such that the numerical aperture NA, represented by the following formula (1), falls within a specific range: core and refractive index n clad may have:

number

[0136] In formula (1), n core represents the refractive index of the cured product of the core resin composition, and n clad represents the refractive index of the cured product of the cladding resin composition. core and refractive index n clad The measurement wavelength is the wavelength of light transmitted through the optical waveguide, and is, for example, 1310 nm. The numerical aperture NA is, specifically, for example, 0.03 or more, preferably 0.04 or more, more preferably 0.05 or more, or 0.06 or more. The upper limit of the numerical aperture NA is, for example, less than 0.3, preferably 0.2 or less, more preferably 0.18 or less, and even more preferably 0.16 or less, or 0.15 or less. The numerical aperture NA can be measured according to the method described in the Examples below.

[0137] The photosensitive resin composition set of the present invention can produce an optical waveguide having a small difference in shrinkage rate between the core layer and the clad layer. For example, when the shrinkage rate S of the core layer is core and the shrinkage rate S of the cladding layer clad The difference between (|S core -S clad |) is preferably less than 0.05, more preferably 0.05 or less, and even more preferably 0.04 or less, 0.03 or less, 0.02 or less, or 0.01 or less. There is no particular lower limit, but it may be 0 or more, 0.0001 or more, etc. The difference in shrinkage rate can be measured according to the method described in the examples below.

[0138] The resin composition contains a combination of components (A) to (E), and therefore exhibits excellent developability (resolution). This allows for the formation of an optical waveguide with excellent fine-line waveguide formability. For example, when attempting to form a line layer with a thickness of 5 μm and an L / S (line / space) of 5 μm / 5 μm, and a line layer with a thickness of 50 μm and an L / S (line / space) of 50 μm / 50 μm, it is preferable to be able to form at least one of them, and particularly preferable to be able to form both. The developability can be evaluated according to the method described in the Examples below.

[0139] The cured product obtained by thermally curing the resin composition at 190°C for 90 minutes exhibits excellent flame retardancy. This results in an optical waveguide with excellent flame retardancy. Specifically, a core resin composition and a clad resin composition are layered together, and the layered core and clad resin compositions are thermally cured at 190°C for 90 minutes to obtain a sample. The flame retardancy of this sample is preferably such that, in a flame retardancy test (UL-94), no combustible material falls, no test piece is completely burned, and the test piece burns for a period of 50 to 250 seconds, more preferably no combustible material falls, no test piece is completely burned, and the test piece burns for a period of less than 50 seconds, and even more preferably, a period of more than 50 seconds. Flame retardancy can be measured according to the method described in the Examples below.

[0140] The resin composition contains a combination of components (A) to (E), and therefore exhibits the property of being able to reduce optical transmission loss before high-temperature storage testing (HTS testing). Specifically, a test substrate having a cladding layer and a core layer formed using the photosensitive resin composition set is produced. The optical transmission loss is measured using this test substrate. In this case, the optical transmission loss is preferably less than 0.5 dB / cm, more preferably less than 0.4 dB / cm. There is no particular lower limit, but it can be 0 dB / cm or more, 0.1 dB / cm or more, etc. The optical transmission loss can be measured according to the method described in the Examples below.

[0141] The resin composition contains a combination of components (A) to (E), and therefore typically exhibits the property of being able to reduce the rate of change in optical transmission loss before and after a high-temperature storage test (HTS test). Specifically, a test substrate having a cladding layer and a core layer formed using the photosensitive resin composition set is prepared. The optical transmission loss before and after the HTS test is measured using this test substrate. In this case, the rate of change in optical transmission loss is preferably less than 30%, more preferably less than 20%, and even more preferably less than 15%. There is no particular lower limit, but it can be 0% or more, 0.1% or more, for example. The rate of change in optical transmission loss can be measured according to the method described in the Examples below.

[0142] [Photosensitive resin sheet set] Photosensitive resin compositions such as a core resin composition and a clad resin composition may be used as a resin sheet. The resin sheet is a sheet having a resin composition layer containing the resin composition. Therefore, a resin sheet having a resin composition layer containing the core resin composition (hereinafter, sometimes referred to as a "core resin sheet") can be obtained from the core resin composition. Furthermore, a resin sheet having a resin composition layer containing the clad resin composition (hereinafter, sometimes referred to as a "clad resin sheet") can be obtained from the clad resin composition. Then, a photosensitive resin sheet set including the core resin sheet and the clad resin sheet can be obtained as a sheet set for manufacturing an optical waveguide. The photosensitive resin sheet set can provide the same advantages as the photosensitive resin composition set described above, and further, it enables the manufacture of an optical waveguide by a lamination method, making the manufacture of an optical waveguide easier.

[0143] <Core resin sheet> The resin composition layer of the core resin sheet usually contains the core resin composition, and preferably contains only the core resin composition. The thickness of the resin composition layer of the core resin sheet can be set depending on the thickness of the core layer. Specific ranges include a thickness of preferably 0.5 μm or more, more preferably 1 μm or more, and even more preferably 3 μm or more, and preferably 100 μm or less, more preferably 50 μm or less, and particularly preferably 20 μm or less.

[0144] The core resin sheet may include a support. For example, the core resin sheet may include a support and a resin composition layer formed on the support. Examples of the support include a polyethylene terephthalate film, a polyethylene naphthalate film, a polypropylene film, a polyethylene film, a polyvinyl alcohol film, and a triacetyl acetate film, with a polyethylene terephthalate film being particularly preferred.

[0145] Examples of commercially available supports include polyethylene terephthalate films such as those manufactured by Oji Paper Co., Ltd. under the product names "Alphan MA-410" and "E-200C," polypropylene films manufactured by Shin-Etsu Film Co., Ltd., and the PS series manufactured by Teijin Ltd. under the product name "PS-25." To facilitate peeling of the support after lamination, the surface of the support may be coated with a release agent such as an alkyd-based release agent or a silicone coating agent.

[0146] The thickness of the support is preferably in the range of 5 μm to 100 μm, and more preferably in the range of 10 μm to 50 μm.

[0147] In addition, in order to reduce scattering of light during exposure to actinic rays such as ultraviolet rays, the support is preferably one with excellent transparency. Specifically, the support is preferably one with a turbidity (haze standardized by JIS-K6714), which is an index of transparency, of 0.1 to 5. Furthermore, the resin composition layer may be protected with a protective film.

[0148] The core resin sheet may be provided with a protective film that protects the resin composition layer. Typically, the protective film is provided on the side of the resin composition layer opposite the support. As the protective film, for example, a film formed from the same material as the support can be used. The adhesive strength between the protective film and the resin composition layer is preferably smaller than the adhesive strength between the support and the resin composition layer. Typically, the core resin sheet is used after peeling off the protective film. Note that it is preferable that the adhesive strength between the resin composition layer and the protective film is smaller than the adhesive strength between the resin composition layer and the support.

[0149] The core resin sheet can be produced, for example, by preparing a resin varnish by dissolving the core resin composition in an organic solvent, applying the resin varnish to a support, and drying the organic solvent by heating or hot air blowing to form a resin composition layer. Specifically, after completely removing bubbles from the core resin composition using a vacuum degassing method or the like, the core resin composition is applied to a support, the solvent is removed using a hot air oven or far-infrared oven, and the resulting resin composition layer is dried. If necessary, a protective film is then laminated on the resulting resin composition layer to produce the core resin sheet. The specific drying conditions vary depending on the curability of the core resin composition and the amount of organic solvent in the resin varnish. For a resin varnish containing 30% to 60% by weight of organic solvent, drying can be performed at 80°C to 120°C for 3 to 13 minutes. The amount of residual organic solvent in the core resin composition layer is preferably 5% by weight or less, more preferably 2% by weight or less, relative to the total amount of the resin composition layer, in order to prevent diffusion of the organic solvent in subsequent processes. Those skilled in the art can determine suitable drying conditions through simple experiments.

[0150] Examples of methods for applying the core resin composition include gravure coating, microgravure coating, reverse coating, kiss reverse coating, die coating, slot die coating, lip coating, comma coating, blade coating, roll coating, knife coating, curtain coating, chamber gravure coating, slot orifice coating, spray coating, and dip coating.

[0151] The core resin composition may be applied in several batches, in one batch, or by a combination of different methods. Among these, the die coating method is preferred because it provides excellent uniformity. To avoid contamination, the application process is preferably carried out in an environment where foreign matter is less likely to be generated, such as a clean room.

[0152] <Clad resin sheet> The resin composition layer of the clad resin sheet usually contains a clad resin composition, and preferably contains only a clad resin composition. The thickness of the resin composition layer of the clad resin sheet can be set depending on the thickness of the clad layer. Specific ranges include a thickness of preferably 5 μm or more, more preferably 7 μm or more, and even more preferably 10 μm or more, and preferably 40 μm or less, more preferably 30 μm or less, and particularly preferably 20 μm or less.

[0153] The clad resin sheet may be the same as the core resin sheet, except that it includes the resin composition layer containing the clad resin composition instead of the resin composition layer containing the core resin composition. Therefore, the clad resin sheet may include a support. The support of the clad resin sheet may be the same as the support of the core resin sheet. Furthermore, the clad resin sheet may include a protective film. The protective film of the clad resin sheet may be the same as the protective film of the core resin sheet. Usually, the clad resin sheet is used after peeling off the protective film.

[0154] The clad resin sheet can be produced by the same method as the core resin sheet, except that the clad resin composition is used instead of the core resin composition.

[0155] The resin composition layer of the clad resin sheet may contain a solvent, but the amount of the solvent is preferably small. In one example, the amount of solvent contained in the resin composition layer of the clad resin sheet may be in the same range as the amount of solvent contained in the resin composition layer of the core resin sheet.

[0156] [Optical Waveguide and Method for Manufacturing Optical Waveguide] The above-described photosensitive resin composition set and photosensitive resin sheet set can be used to manufacture an optical waveguide. Hereinafter, an embodiment of the optical waveguide will be described with reference to the drawings.

[0157] FIG. 1 is a perspective view schematically illustrating an optical waveguide 10 according to one 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 includes a cured product of the core resin composition of the present invention, and preferably includes only the cured product of the core resin composition of the present invention. The cladding layer 200 includes a cured product of the cladding resin composition of the present invention, and preferably includes only the cured product of the cladding resin composition of the present invention. The cured product of the cladding resin composition preferably has a lower refractive index than the cured product of the core resin composition.

[0158] The core layer 100 is provided in the clad layer 200. Thus, the core layer 100 is covered by the clad layer 200. Usually, the entire peripheral surface of the core layer 100 is covered by the clad layer 200. The core layer 100 and the clad layer 200 are in direct contact with each other without any other layer therebetween, and therefore, an interface 100I can be formed between the core layer 100 and the clad layer 200. Usually, the core layer 100 has a higher refractive index than the clad layer 200, and therefore, light (not shown) can be transmitted within the core layer 100 from one end (incident end) 100A of the core layer 100 to the other end (exit end) 100B.

[0159] The wavelength of light that can be transmitted through the optical waveguide 10 can be selected from a variety of wavelengths. For example, preferred wavelength ranges of the transmitted light can be 840 nm to 860 nm (e.g., 850 nm), 1300 nm to 1320 nm (e.g., 1310 nm), 1540 nm to 1560 nm (e.g., 1550 nm), etc. Among these, the wavelength range of the light transmitted through the optical transmission line 10 is preferably 1300 nm to 1320 nm.

[0160] The optical waveguide 10 may be a single-mode optical waveguide or a multi-mode optical waveguide, but is preferably a single-mode optical waveguide. In particular, the optical waveguide 10 is preferably a single-mode optical waveguide for light in the preferred wavelength range described above. For example, the optical waveguide 10 is preferably a single-mode optical waveguide for light of 1310 nm.

[0161] It is desirable to set the width L of the core layer 100 appropriately within a range that allows light transmission. A 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, and particularly preferably 2 μm or more, and is preferably 50 μm or less, more preferably 30 μm or less, and 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 when viewed in the thickness direction.

[0162] The spacing S of the core layers 100 is desirably set appropriately within a range that allows light transmission. A specific range for the spacing S of the core layers 100 is preferably 50 μm or more, more preferably 70 μm or more, and particularly preferably 100 μm or more, and is preferably 1000 μm or less, more preferably 500 μm or less, and particularly preferably 300 μm or less. The spacing S of the core layers 100 corresponds to the spacing (space) between the core layers as viewed in the thickness direction.

[0163] It is desirable to set the thickness T of the core layer 100 appropriately within a range that allows light transmission. A specific range of the thickness T of the core layer 100 is preferably 0.5 μm or more, more preferably 1 μm or more, and particularly preferably 2 μm or more, and is preferably 50 μm or less, more preferably 30 μm or less, and particularly preferably 20 μm or less, and may be 10 μm or less.

[0164] The thickness of the cladding layer 200 is usually greater than the thickness of the core layer 100. The specific thickness of the cladding layer 200 is preferably 5 μm or more, more preferably 7 μm or more, and particularly preferably 10 μm or more, and is preferably 40 μm or less, more preferably 30 μm or less, and particularly preferably 20 μm or less.

[0165] The optical waveguide 10 may include any element other than the core layer 100 and the clad layer 200, as needed. For example, the optical waveguide 10 may include a substrate 300. In the optical waveguide 10 including the substrate 300, the clad layer 200 is usually provided on the substrate 300, and the core layer 100 is provided within the clad layer 200.

[0166] The substrate 300 may be a hard substrate such as a glass substrate, a metal substrate, a ceramic substrate, a wafer, or a circuit board. Examples of the wafer include semiconductor wafers such as silicon wafers, gallium arsenide (GaAs) wafers, indium phosphide (InP) wafers, gallium phosphide (GaP) wafers, gallium nitride (GaN) wafers, gallium telluride (GaTe) wafers, zinc selenium (ZnSe) wafers, and silicon carbide (SiC) wafers, or pseudo wafers. Examples of the pseudo wafer include a plate-shaped member including a molding resin and electronic components embedded in the molding resin. 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 patterned conductor layer (circuit) formed on one or both sides of the above-mentioned substrate. Furthermore, the substrate 300 may be a film formed of a plastic material such as polyethylene terephthalate, polyimide, or polyester. Furthermore, a flexible circuit board may be employed as the substrate 300 .

[0167] The optical waveguide 10 may also include, as an optional element, a protective layer (not shown) that protects the core layer 100 and the cladding layer 200. For example, the protective layer may be provided so as to cover the surface of the cladding layer 200 opposite to the substrate 300.

[0168] As described above, the optical waveguide 10 can have a small transmission loss. Furthermore, the optical waveguide 10 can be formed using a core resin composition and a cladding resin composition that have excellent core formability and can suppress the occurrence of surface irregularities, so that the core layer can be formed into fine wiring, and it can be formed with a small line width L as described above.

[0169] The optical waveguide 10 can be produced using either the photosensitive resin composition set of the present invention or the photosensitive resin sheet set of the present invention. Step (I) of forming a first composition layer containing a cladding resin composition; Step (II) of curing the first composition layer; Step (III) of forming a second composition layer containing a core resin composition on the first composition layer; a step (IV) of exposing the second composition layer to light; a step (V) of subjecting the second composition layer to a development treatment; Step (VI) of curing the second composition layer; Step (VII) of forming a third composition layer containing a cladding resin composition on the second composition layer; Step (VIII) of curing the third composition layer; It can be produced by a method comprising the steps of:

[0170] 2 is a schematic cross-sectional view illustrating step (I) of a method for manufacturing an optical waveguide according to one embodiment of the present invention. As shown in FIG. 2, the method for manufacturing an optical waveguide according to one embodiment of the present invention includes step (I) of forming a first composition layer 210 containing a cladding resin composition. In this embodiment, an example of forming the first composition layer 210 on a substrate 300 will be described.

[0171] There are no particular limitations on the method for forming the first composition layer 210. For example, the first composition layer 210 may be formed by applying a cladding resin composition onto the substrate 300. From the viewpoint of smooth application, a varnish-like cladding resin composition containing a solvent may be prepared, and the varnish-like cladding resin composition may be applied.

[0172] Examples of coating methods include gravure coating, microgravure coating, reverse coating, kiss reverse coating, die coating, slot die coating, lip coating, comma coating, blade coating, roll coating, knife coating, curtain coating, chamber gravure coating, slot orifice coating, spin coating, slit coating, spray coating, dip coating, hot melt coating, bar coating, applicator coating, air knife coating, curtain flow coating, offset printing, brush coating, and screen printing.

[0173] The cladding resin composition may be applied in one application or in multiple applications. It may also be applied by a combination of different application methods. To avoid contamination, it is preferable to apply the composition in an environment where foreign matter is unlikely to be generated, such as a clean room.

[0174] After application of the cladding resin composition, the first composition layer 210 may be dried, if necessary. Drying can be performed using a drying device such as a hot air oven or a far-infrared oven. Drying conditions are preferably set appropriately depending on the composition of the cladding resin composition. Specific examples include a drying temperature of preferably 50°C or higher, more preferably 70°C or higher, and particularly preferably 80°C or higher, and a drying time of preferably 30 seconds or higher, more preferably 60 seconds or higher, and particularly preferably 120 seconds or higher, and a drying time of preferably 60 minutes or shorter, more preferably 20 minutes or shorter, and particularly preferably 5 minutes or shorter.

[0175] The first composition layer 210 may be formed, for example, using a clad resin sheet including a support and a resin composition layer made of a clad resin composition. Specifically, the first composition layer 210 can be formed on the substrate 300 by laminating the clad resin composition layer of the clad resin sheet onto the substrate 300. Lamination is typically performed by heating the clad resin composition layer of the resin sheet while pressing it onto the substrate 300. This lamination is preferably performed under reduced pressure by a vacuum lamination method. Furthermore, prior to lamination, a preheating treatment may be performed, in which the resin sheet and substrate are heated, if necessary.

[0176] The lamination conditions are, for example, a pressure bonding temperature (lamination temperature) of 70°C to 140°C and a pressure bonding pressure of 1 kgf / cm. 2 ~11kgf / cm 2 (9.8×10 4 N / m 2 ~107.9×10 4 N / m 2) and a pressure bonding time of 5 to 300 seconds. Furthermore, 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 in a batch system or continuously using a roll.

[0177] The vacuum lamination method can be performed using a commercially available vacuum laminator, such as a vacuum applicator manufactured by Nikko Materials Co., Ltd., a vacuum pressure laminator manufactured by Meiki Seisakusho Co., Ltd., a roll-type dry coater manufactured by Hitachi Industries Co., Ltd., or a vacuum laminator manufactured by Hitachi AIC Corporation.

[0178] 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 the step (III).

[0179] The first composition layer 210 formed on the substrate 300 in step (I) usually contains a cladding resin composition, and preferably contains only a cladding resin composition.

[0180] The method for producing an optical waveguide according to one embodiment of the present invention includes, after step (I), step (II) of curing the first composition layer 210. This step (II) may involve, for example, heat treating the first composition layer 210. The conditions for the heat treatment may be selected depending on the type and amount of the resin component in the cladding resin composition, and may be preferably 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 carried out in an inert atmosphere such as a nitrogen atmosphere.

[0181] Alternatively, the first composition layer 210 may be cured by exposure treatment. In one example, the specific exposure dose range is preferably 10 mJ / cm 2 2 More preferably, 50 mJ / cm 2 More than 200 mJ / cm 2 or more, preferably 10,000 mJ / cm 2Less than or equal to 8,000 mJ / cm 2 or less, more preferably 4,000 mJ / cm 2 Below 1,000 mJ / cm, particularly preferably 2 The first composition layer 210 may also be cured by a combination of exposure treatment and heat treatment.

[0182] 3 is a schematic cross-sectional view illustrating step (II) of the method for producing an optical waveguide according to one embodiment of the present invention. By curing the first composition layer 210 in step (II), a cured first composition layer 220 is obtained on the substrate 300, as shown in FIG. 3. This cured first composition layer 220 forms a part of the cladding layer 200, and may be referred to as the "lower cladding layer" 220 hereinafter.

[0183] 4 is a schematic cross-sectional view illustrating step (III) of the method for producing an optical waveguide according to one embodiment of the present invention. The method for producing an optical waveguide according to one embodiment of the present invention includes, after step (II), step (III) of forming a second composition layer 110 containing a core resin composition on a lower clad layer 220 as a cured first composition layer, as shown in FIG.

[0184] There are no particular limitations on the method for forming the second composition layer 110. For example, the second composition layer 110 may be formed by applying a core resin composition onto the lower clad layer 220. From the viewpoint of smooth application, a varnish-like core resin composition containing a solvent may be prepared and then applied. The core resin composition may be applied in the same manner as the clad resin composition. After application of the core resin composition, the second composition layer 110 may be dried, if necessary. The second composition layer 110 may be dried using the same method and conditions as those for drying the first composition layer 210.

[0185] The second composition layer 110 may be formed, for example, using a core resin sheet. As a specific example, the resin composition layer of the core resin sheet is laminated onto the lower clad layer 220, thereby forming the second composition layer 110 on the lower clad layer 220. The core resin sheet can be laminated in the same manner as the clad resin sheet. The support for the core resin sheet is peeled off at an appropriate time before step (V).

[0186] The second composition layer 110 formed on the lower clad layer 220 in step (III) usually contains a core resin composition, and preferably contains only a core resin composition.

[0187] 5 is a schematic cross-sectional view illustrating step (IV) of the method for producing an optical waveguide according to one embodiment of the present invention. As shown in FIG. 5, the method for producing an optical waveguide according to one embodiment of the present invention includes, after step (III), step (IV) of exposing the second composition layer 110 to light.

[0188] In step (V), a latent image is formed in the second composition layer 110 by exposure treatment. Specifically, in the exposure treatment, light P is selectively irradiated onto specific portions of the second composition layer 110. Therefore, after the exposure treatment, the second composition layer 110 is provided with exposed portions 111 that have been irradiated with light and unexposed portions 112 that have not been irradiated with light. Typically, the core resin composition functions as a negative-type photosensitive resin composition, so the exposed portions 111 form a latent image corresponding to the core layer.

[0189] From the viewpoint of performing selective exposure, the exposure treatment in step (V) is usually performed using a mask 400. Specifically, in this exposure treatment, light P is irradiated onto the second composition layer 110 through the mask 400 having light-transmitting portions 410 and light-shielding portions 420. The light P passes through the light-transmitting portions 410 and enters the exposed portions 111, but cannot pass through the light-shielding portions 420 and therefore cannot enter the non-exposed portions 112. Thus, the exposed portions 111 and non-exposed portions 112 corresponding to the light-transmitting portions 410 and light-shielding portions 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 (contact exposure method) as shown in FIG. 5 , or exposure may be performed using parallel light without being in close contact (non-contact exposure method).

[0190] Generally, the light-transmitting portion 410 of the mask 400 is formed to have a planar shape corresponding to the core layer of the optical waveguide. Therefore, the light-shielding portion 420 of the mask 400 is formed to have a planar shape corresponding to the portion of the optical waveguide where the core layer is not present. Unless otherwise specified, the "planar shape" refers to the shape as viewed from the thickness direction. The light-transmitting portion 410 formed in a planar shape corresponding to the core layer may be referred to as a "mask pattern" hereinafter.

[0191] As the light P used in the exposure treatment in step (V), it is preferable to use an appropriate actinic ray according to the composition of the core resin composition. The wavelength of the actinic ray is usually 190 nm to 1000 nm, preferably 240 nm to 550 nm, but light of other wavelengths may also be used. Specific examples of actinic light sources include ultraviolet light, visible light, electron beams, X-rays, etc., with ultraviolet light being particularly preferred. The exposure dose 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 dose in step (V) is preferably 10 mJ / cm 2 More preferably, 50 mJ / cm 2 More than 200 mJ / cm 2 or more, preferably 10,000 mJ / cm 2 Less than or equal to 8,000 mJ / cm 2 or less, more preferably 4,000 mJ / cm 2Below 1,000 mJ / cm, particularly preferably 2 The following is the result.

[0192] When the second composition layer 110 is formed using the resin sheet of the present invention, in step (IV), a support (not shown) may be present on the second composition layer 110. When a support is present on the second composition layer 110, exposure may be performed through the support, or exposure may be performed after peeling off the support.

[0193] The core resin composition generally functions as a negative photosensitive resin composition, and therefore has reduced solubility in a developer in the exposed areas 111. On the other hand, the non-exposed areas 112 have high solubility in a developer. Utilizing this difference in solubility between the exposed areas 111 and the non-exposed areas 112, the subsequent development process in step (VI) is carried out.

[0194] The method for producing an optical waveguide according to one embodiment of the present invention may include step (IX) of heating the second composition layer 110 after step (IV) and before step (V) in order to harden the second composition layer 110. Step (IX) can quickly reduce the solubility of the exposed portion 111 in a developer. Heating in step (IX) may be performed using a hot plate or an oven. The heating temperature may be, for example, 40°C or higher and 110°C or lower. The heating time may be, for example, 30 seconds or higher and 60 minutes or lower.

[0195] FIG. 6 is a schematic cross-sectional view illustrating step (V) of a method for producing an optical waveguide according to one embodiment of the present invention. The method for producing an optical waveguide according to one embodiment of the present invention includes step (V) of subjecting the second composition layer 110 to a development treatment after step (IV). The development treatment allows the latent image formed in step (IV) to be developed. Since the core resin composition typically functions as a negative photosensitive resin composition, as shown in FIG. 6, the development treatment does not remove the exposed portion 111, but removes the unexposed portion 112 (see FIG. 5). 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).

[0196] The developing method is usually a wet developing method in which the second composition layer 110 is brought into contact with a developer, and an alkaline aqueous solution is usually used as the developer.

[0197] Examples of alkaline aqueous solutions used as developers include aqueous solutions of alkali metal compounds. Examples of alkali metal compounds include alkali metal hydroxides such as lithium hydroxide, sodium hydroxide, and potassium hydroxide; alkali metal carbonates or bicarbonates such as sodium carbonate and sodium bicarbonate; alkali metal phosphates such as sodium phosphate and potassium phosphate; and alkali metal pyrophosphates such as sodium pyrophosphate and potassium pyrophosphate. Examples of alkaline aqueous solutions include aqueous solutions of metal ion-free organic bases such as tetraalkylammonium hydroxide. One type of alkaline aqueous solution may be used alone, or two or more types may be used in combination. Among these, alkali metal carbonates or bicarbonates are preferred, with sodium carbonate being more preferred, from the viewpoint of achieving the effects of the present invention more significantly.

[0198] The developer may contain additives such as surfactants and antifoaming agents, if necessary, to improve the developing action.

[0199] The development time is preferably 10 seconds to 5 minutes. The temperature of the developer during development is not particularly limited, but is preferably 20°C or higher and 50°C or lower, more preferably 40°C or lower.

[0200] Examples of development methods include puddle, spray, immersion, brushing, slapping, and ultrasonic methods. Among these, the spray method is suitable for improving resolution. When using the spray method, the spray pressure is preferably 0.05 MPa to 0.3 MPa.

[0201] After development using the developer, the second composition layer 110 may be further rinsed. Rinsing is preferably carried out with a solvent different from the developer. For example, rinsing may be carried out with the same type of solvent contained in the core resin composition or water. The rinsing time is preferably 5 seconds to 1 minute.

[0202] After development using a developer, a desmear treatment may be carried out to remove unexposed areas 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.

[0203] The method for producing an optical waveguide according to one embodiment of the present invention includes, after step (V), step (VI) of curing the second composition layer 110. This step (VI) typically includes heat-treating the second composition layer 110. The conditions for the heat treatment may be selected depending on the type and amount of the resin component in the core resin composition. For example, the conditions for the heat treatment in step (VI) may be the same as the conditions for the heat treatment of the first composition layer 210 in step (II).

[0204] 7 is a schematic cross-sectional view illustrating step (VI) of the method for producing an optical waveguide according to one embodiment of the present invention. By curing second composition layer 110 in step (VI), core layer 100 is obtained as a cured second composition layer on lower cladding layer 220, as shown in FIG.

[0205] 8 is a schematic cross-sectional view illustrating step (VII) of the method for producing an optical waveguide according to one embodiment of the present invention. As shown in FIG. 8, the method for producing an optical waveguide according to one embodiment of the present invention includes, after step (VI), step (VII) of forming a third composition layer 230 containing a cladding resin composition on the core layer 100. The third composition layer 230 is usually formed so as to cover the entire peripheral 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.

[0206] There are no particular limitations on the method for forming the third composition layer 230. For example, the third composition layer 230 may be formed by applying a cladding resin composition to the core layer 100 (and, if necessary, on the lower cladding layer 220). The application of the cladding resin composition to form the third composition layer 230 may be carried out in the same manner as the application of the cladding resin composition to form the first composition layer 210. Furthermore, after application of the cladding resin composition, the third composition layer 230 may be dried, if necessary. The third composition layer 230 may be dried using the same method and conditions as those used to dry the first composition layer 210.

[0207] The third composition layer 230 may be formed using, for example, a clad resin sheet. As a specific example, the third composition layer 230 can be formed on the core layer 100 by laminating a resin composition layer of the clad resin sheet onto the core layer 100 (and, if necessary, the lower clad layer 220). The lamination of the clad resin sheet to form the third composition layer 230 can be performed in the same manner as the lamination of the clad resin sheet to form the first composition layer 210. When the third composition layer 230 is formed using a clad resin sheet provided with a support, the support may be peeled off in any step.

[0208] The third composition layer 230 formed on the core layer 100 in step (VII) usually contains a cladding resin composition, and preferably contains only a cladding resin composition.

[0209] The method for producing an optical waveguide according to one embodiment of the present invention includes, after step (VII), step (VIII) of curing the third composition layer 230. The effect of the third resin composition layer 230 in step (VIII) can usually be achieved in the same way as the curing of the first composition layer 210.

[0210] 9 is a schematic cross-sectional view illustrating step (VIII) of the method for producing an optical waveguide according to one embodiment of the present invention. By curing the third composition layer 230 in step (VIII), a cured third composition layer 240 is obtained on the core layer 100, as shown in FIG. 9. This cured third composition layer 240 forms a part of the cladding layer 200 and may be referred to as the "upper cladding layer" 240 hereinafter. The cladding layer 200 is formed from this upper cladding layer 240 and the lower cladding layer 220. Therefore, an optical waveguide 10 can be obtained, which includes 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.

[0211] The method for manufacturing the optical waveguide 10 may further include any optional steps in combination with the steps described above.

[0212] The method for manufacturing the optical waveguide 10 may include, for example, a step of forming a protective layer (not shown). The method for manufacturing the optical waveguide 10 may also include, for example, a step of dicing the manufactured optical waveguide 10.

[0213] The above-described steps may be repeated in the method for manufacturing the optical waveguide 10. For example, steps (I) to (VIII) may be repeated to manufacture an optical waveguide having a multilayer structure in which core layers and clad layers are alternately provided on the substrate 300 in the thickness direction.

[0214] [Opto-electric hybrid board and its manufacturing method] An opto-electrical hybrid board according to one embodiment of the present invention includes the optical waveguide described above. Typically, the opto-electrical hybrid board includes an optical waveguide and an electric circuit board. The electric 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; and active components such as semiconductor chips. The optical waveguide and the wiring of the electric circuit board may be connected via an opto-electrical conversion element. The opto-electrical conversion element may include a combination of a light-emitting element (e.g., a surface-emitting light-emitting diode) capable of converting electricity to light and a light-receiving element (e.g., a photodiode) capable of converting light to electricity. Furthermore, the opto-electrical hybrid board may include an optical element such as a mirror for adjusting the optical path.

[0215] A preferred example of an opto-electrical hybrid substrate is one that includes a chip in which an optical integrated circuit is formed on a silicon wafer. This chip is expected to be put to practical use in the near future using silicon photonics, and is expected to be mounted, for example, in a semiconductor package. An opto-electrical hybrid substrate that includes this chip includes, for example, an electric circuit board, a chip mounted on the electric circuit board, and an optical waveguide. The optical waveguide can be used to connect the wiring of the electric circuit board to the chip or to connect multiple chips together.

[0216] Chips manufactured using silicon photonics generally use light with wavelengths of 1310 nm and 1550 nm, with 1310 nm being the most common (Sho Yoshida, Daisuke Suganuma, and Takaaki Ishigure, "Fabrication of Single-Mode Polymer Waveguides Using the Mosquito Method and Low Loss," 28th Spring Conference of the Japan Institute of Electronics Packaging, 2014). Therefore, it is preferable that the optical waveguide be capable of transmitting light with wavelengths of 1310 nm and 1550 nm or close to these wavelengths, and for example, it is preferable that the optical waveguide be capable of transmitting light with wavelengths of 1300 nm to 1320 nm. The optical waveguides according to the above-described embodiments are capable of transmitting light with these wavelengths.

[0217] Generally, between single mode and multimode, single mode can achieve faster transmission. Therefore, from the viewpoint of high-speed transmission, single mode optical waveguides are preferable as optical waveguides applied to opto-electrical hybrid circuits. In single mode optical waveguides, 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. Furthermore, optical waveguides having such a narrow core layer are preferable from the viewpoint of increasing the degree of freedom in package design when the optical waveguide is applied to a semiconductor package. According to the optical waveguides of the above-described embodiments, it is possible to reduce the width of the core layer as described above.

[0218] On the other hand, when connecting multiple opto-electrical hybrid boards, the boards may be connected via optical fibers. For example, multiple opto-electrical hybrid boards may be installed in a rack and connected to each other via optical fibers. Multimode optical fibers are the mainstream for connecting boards in this way. Therefore, from the perspective of enabling connection with optical fibers, a multimode optical waveguide may be used as the optical waveguide provided in the opto-electrical hybrid board.

[0219] From the viewpoint of enhancing versatility, it is desirable that the optical waveguide be applicable to both single-mode and multi-mode. Furthermore, it is desirable to reduce the minimum width of the core layer of such optical waveguides to increase the degree of freedom in the line width of the core layer. According to the optical waveguides of the above-described embodiments, by using a core resin composition, it is possible to form a fine core and suppress the occurrence of core surface irregularities, thereby reducing the minimum width of the core layer. Furthermore, according to the optical waveguides of the above-described embodiments, both single-mode and multi-mode optical waveguides can be obtained. Therefore, the optical waveguides of the above-described embodiments can be applied in a wide range of applications. Furthermore, because the optical waveguides of the above-described embodiments are applicable in such a wide range of applications and can suppress optical transmission loss, they are suitable for application to opto-electrical hybrid boards.

[0220] Since the opto-electric hybrid board includes the optical waveguide described above, the manufacturing method of the opto-electric hybrid board includes the same method as the manufacturing method of the optical waveguide. [Example]

[0221] The present invention will be described in detail below 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 "% by mass", respectively, unless otherwise specified. Furthermore, the operations described below were carried out in air at room temperature and normal pressure (23°C, 1 atmosphere) unless otherwise specified. However, Example 10 is a reference example.

[0222] <Synthesis Example 1: Synthesis of Naphthol Aralkyl Skeleton-Containing Acid-Modified Epoxy Acrylate Resin> 325 parts of a naphthol aralkyl epoxy resin ("ESN-475V" manufactured by Nippon Steel Chemical & Material Co., Ltd.) with an epoxy equivalent of 330 g / eq. was placed in a flask equipped with a gas inlet tube, a stirrer, a condenser, and a thermometer. 340 parts of propylene glycol monomethyl ether was added and dissolved by heating. 0.46 parts of hydroquinone and 1 part of triphenylphosphine were then added. The mixture was heated to 95-105°C, and 72 parts of acrylic acid were slowly added dropwise and allowed to react for 16 hours. The reaction product was cooled to 80-90°C, and 130 parts of tetrahydrophthalic anhydride was added. The reaction was allowed to react for 8 hours and then cooled. The solvent was removed to obtain an acid-modified epoxy acrylate resin with an acid value of 90 mgKOH / g and a solids content of 70% by mass. The weight-average molecular weight was 1,000.

[0223] <Production Example 1: Production of Core Resin Composition>

[0049] 21.5 parts of the naphthol aralkyl skeleton-containing ester-type acid-modified epoxy acrylate resin 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: approximately 330 g / eq.), 5 parts of a naphthalene-type tetrafunctional epoxy resin ("HP-4710" manufactured by DIC Corporation, epoxy equivalent: 170 g / eq.), 12.5 parts of a photoreactive resin ("DPHA" manufactured by Nippon Kayaku Co., Ltd., dipentaerythritol hexaacrylate), 12.5 parts of a photopolymerization initiator ("Omnirad" manufactured by IGM Co., Ltd.), 10 parts of a naphthol aralkyl skeleton epoxy resin ("ESN-475V" manufactured by Nippon Steel Chemical & Material Co., Ltd., epoxy equivalent: approximately 330 g / eq.), 5 parts of a naphthalene-type tetrafunctional epoxy resin ("HP-4710" manufactured by DIC Corporation, epoxy equivalent: 170 g / eq.), 12.5 parts of a photoreactive resin ("DPHA" manufactured by Nippon Kayaku Co., Ltd., dipentaerythritol hexaacrylate), 10 parts of a photopolymerization initiator ("Omnirad" manufactured by IGM Co., Ltd.), 10 parts of a naphthol aralkyl skeleton epoxy resin ("ESN-475V" manufactured by Nippon Steel Chemical & Material Co., Ltd., epoxy equivalent: approximately 330 g / eq.), 10 parts of a naphthalene-type tetrafunctional epoxy resin ("HP-4710" manufactured by DIC Corporation, epoxy equivalent: 170 g / eq.), 10 parts of a photopolymerization initiator ("Omnirad" manufactured by IGM Co., Ltd.), 10 parts of a photopolymerization initiator ("Omnirad" 1.5 parts of a curing accelerator (2-phenyl-1-benzyl-1H-imidazole, manufactured by Shikoku Chemical Industries, Ltd.), 0.2 parts of a flame retardant (FP-100, manufactured by Fushimi Pharmaceutical Co., Ltd.), 15 parts of methyl ethyl ketone, and 1.5 parts of propylene glycol monomethyl ether were mixed together and used in a high-speed rotating mixer to prepare a varnish-like core resin composition.

[0224] <Production Examples 2 to 14: Production of core and clad resin compositions> Core and clad resin compositions were produced in the same manner as in Example 1, except that the components were mixed according to the formulation shown in the table below. In the table, the blend amount of each component means parts by mass and represents the actual amount used. Production Examples 1, 2, and 10 are core resin compositions, and Production Examples 2 to 9 and 11 to 14 are clad resin compositions. [Table 1]

[0225] The abbreviations in the table are as follows: Component (A) Synthesis Example 1: Carboxy group-containing resin synthesized in Synthesis Example 1 (B) Component HP-4710: Naphthalene-type tetrafunctional epoxy resin (DIC "HP-4710", epoxy equivalent 170g / eq.) ESN-475V: Naphthalene-type epoxy resin (Nippon Steel Chemical & Material Co., Ltd. "ESN-475V", epoxy equivalent: approx. 330g / eq.) (C) Component DPHA: Dipentaerythritol hexaacrylate (Nippon Kayaku Co., Ltd., acrylic equivalent: approximately 96 g / eq.) (D) Component Omnirad 379EG: Compound represented by the following structure (manufactured by IGM, molecular weight 380.5, 2-dimethylamino-2-(4-methyl-benzyl)-1-(4-morpholin-4-yl-phenyl)-butan-1-one, CAS 119344-86-4) [ka] (E) Component FP-100: A compound represented by the following structure (manufactured by Fushimi Pharmaceutical Co., Ltd.) [ka] SPS-100: A compound represented by the following structure (manufactured by Otsuka Chemical Co., Ltd.) [ka] SR-3000: A compound represented by the following structure (manufactured by Daihachi Chemical Industry Co., Ltd.) [ka] PX-200: A compound represented by the following structure (manufactured by Daihachi Chemical Industry Co., Ltd.) [ka] FP-390: A compound represented by the following structure (manufactured by Fushimi Pharmaceutical Co., Ltd.) In the formula, n represents an integer of 3 to 25. [ka] HCA-HQ: The compound represented by the following structure (manufactured by Sankosha) was crushed and divided into particles using the following method. 50 mg of HCA-HQ powder, 2 g of nonionic dispersant ("T208.5" manufactured by NOF Corporation), and 40 g of pure water were weighed into a vial and dispersed ultrasonically for 20 minutes. The particle size distribution was measured using a laser diffraction particle size analyzer (LA-950 manufactured by Horiba, Ltd.) using the batch cell method, and the average particle size was calculated. The average particle size was 0.65 μm. [ka] (F) Component 1B2PZ: 2-phenyl-1-benzyl-1H-imidazole, manufactured by Shikoku Chemical Industry Co., Ltd. (H) Component Melamine: Nissan Chemical Co., Ltd.

[0226] <Preparation of core and clad resin sheets> A polyethylene terephthalate film ("Lumirror T6AM" manufactured by Toray Industries, Inc., thickness 38 μm, softening point 130°C) was prepared as a support. The varnish-like resin composition prepared above was uniformly applied to the support using a die coater so that the thickness of the resin composition layer after drying would be 5 μm, 6.5 μm, 10 μm, 20 μm, and 50 μm, and the support was dried at 80°C to 110°C (maximum temperature 110°C) for 7 minutes to form each resin composition layer. Next, a protective film (biaxially oriented polypropylene film, "MA-411" manufactured by Oji F-Tex Co., Ltd.) was placed on the surface of the resin composition layer and laminated at 80°C to produce a resin sheet with a three-layer structure of support / resin composition layer / protective film.

[0227] <Measurement of refractive index of cured resin composition> The protective film was peeled off from a resin sheet having a 6.5 μm-thick resin composition layer. The resin sheet was then laminated onto a silicon wafer at 80°C, and the support was peeled off to form a 6.5 μm-thick resin composition layer on the silicon wafer. Thereafter, the resin composition layer was exposed to light at an optimum exposure dose of 5000 mJ using a projection exposure device (Ushio Inc.'s "UFX-2240"). After exposure, a 1.0 mass% aqueous solution of tetramethylammonium hydroxide at 23°C was sprayed onto the resin composition layer as a developer at a spray pressure of 0.1 MPa for 30 seconds to perform spray development. After spray development, the resin composition layer was exposed to light at 3 J / cm 2 The resin composition layer was then subjected to ultraviolet irradiation at 190°C for 90 minutes in a nitrogen atmosphere to obtain a sample formed of a cured resin composition layer. The refractive index (1310 nm) of the obtained sample was measured at room temperature and atmospheric pressure using a 2010M type prism coupler (manufactured by Metricon) with a 1310 nm laser beam.

[0228] <Measurement of shrinkage rate> The protective film was peeled off from a resin sheet having a 10 μm-thick resin composition layer. The resin sheet was placed on a 6-inch silicon wafer so that the resin composition layer and the silicon wafer were in contact, and laminated using a vacuum laminator ("VP160" manufactured by Nikko Materials Co., Ltd.). The lamination conditions were a vacuum time of 30 seconds, a pressure bonding temperature of 60°C, a pressure bonding pressure of 0.3 MPa, and a pressure application time of 30 seconds. The support was then peeled off to obtain a laminate having a silicon wafer and a resin composition layer.

[0229] The resin composition layer of the obtained laminate was exposed to ultraviolet light using a projection exposure device (Ushio Inc.'s "UFX-2240") with exposure energy such that the number of remaining gloss steps on a 41-step tablet would be 8 to 10. The exposure was carried out using a quartz glass mask having a mask pattern capable of drawing multiple straight lines with a length of 5 cm and an L / S (line / space) of 5 μm / 100 μm. In the L / S of this quartz glass mask, the lines correspond to the width of the core layers, and the spaces correspond to the spacing between the core layers. After exposure, the substrate was left to stand at room temperature for 30 minutes, and then the support was peeled off. The entire surface of the resin composition layer was spray-developed with a 1% by mass aqueous solution of sodium carbonate at 30°C as the developer at a spray pressure of 0.2 MPa for 1 minute. After spray development, a 2 J / cm 2 The silicon wafer was cleaved in a direction perpendicular to the lines of the obtained core, and the cross section was observed under a microscope. The vertical and horizontal lengths of the rectangular core were measured and the area was calculated (α). The wafer was then placed in a clean oven and heated from room temperature to 190°C. After reaching 190°C, the resin composition layer was cured by heat treatment for 69 minutes. After the resin composition layer was cured, the same cross section was observed, and the vertical and horizontal lengths of the rectangular core were measured and the area was calculated (β). The shrinkage rate c was calculated from the calculated α and β.

number

[0230] Example 1 (Evaluation of developability) -Sample preparation- A glass epoxy substrate (copper-clad laminate) with an 18 μm-thick copper layer was roughened with a surface treatment agent (CZ8100, manufactured by MEC Co., Ltd.) containing an organic acid to prepare a substrate. Next, the protective film was peeled off from a resin sheet with a 10 μm-thick resin composition layer manufactured using the resin composition of Production Example 2. The resin sheet was placed on the copper-clad laminate so that the resin composition layer and the copper-clad laminate were in contact, and the laminate was laminated using a vacuum laminator ("VP160" manufactured by Nikko Materials Co., Ltd.). The lamination conditions were a vacuum time of 30 seconds, a pressure temperature of 60°C, a pressure of 0.3 MPa, and a pressure time of 30 seconds. The support was then peeled off, and the substrate was exposed to ultraviolet light using a projection exposure system ("UFX-2240" manufactured by Ushio Inc.) at an exposure energy of 2 J / cm, which resulted in 8 gloss-remaining steps on a 41-step tablet. After exposure, the laminate was exposed to ultraviolet light at an exposure energy of 2 J / cm. 2 The laminate was then placed in a clean oven, heated from room temperature to 190°C, and after reaching 190°C, heated for 90 minutes in a nitrogen atmosphere to cure the resin composition layer. A lower clad layer was formed by curing the resin composition layer, and an intermediate laminate I comprising a copper-clad laminate and a lower clad layer was obtained.

[0231] Next, the protective film was peeled off from a 5 μm-thick resin sheet produced using the resin composition of Production Example 1. The resin sheet was placed on the lower clad layer so that the resin composition layer of the resin sheet and the lower clad layer of intermediate laminate I were in contact with each other, and laminated using a vacuum laminator ("VP160" manufactured by Nikko Materials Co., Ltd.) to form a resin composition layer on the lower clad layer. The lamination conditions were a vacuum time of 30 seconds, a pressure bonding temperature of 60°C, a pressure bonding pressure of 0.3 MPa, and a pressure time of 30 seconds. This resulted in a laminate comprising a copper-clad laminate, a lower clad layer, and a resin sheet in this order. The support was then peeled off to expose the resin composition layer.

[0232] The resin composition layer was exposed to ultraviolet light using a projection exposure device (Ushio Inc.'s "UFX-2240") with an exposure energy such that the number of remaining gloss steps on a 41-step tablet was 8. The exposure was carried out using a quartz glass mask having a first mask pattern that drew straight lines with an L / S (line / space) of 50 μm / 50 μm and a second mask pattern that drew straight lines with an L / S (line / space) of 5 μm / 5 μm. After exposure, the layer was left to stand at room temperature for 30 minutes, and then the support was peeled off. The entire surface of the resin composition layer was spray-developed with a 1% by mass aqueous solution of sodium carbonate at 30°C as the developer at a spray pressure of 0.2 MPa for 1 minute. After spray development, a 2 J / cm 2 The sample was then subjected to ultraviolet irradiation at 190°C for 1 hour in a nitrogen atmosphere, thereby obtaining Sample A, which was provided in this order with a copper-clad laminate, a lower clad layer, and a 5 μm-thick line layer (a layer formed from the cured product of the resin composition).

[0233] The protective film was peeled off from a 50 μm-thick resin sheet produced using the resin composition of Production Example 1. The resin sheet was placed on the lower clad layer of intermediate laminate I so that the resin composition layer of the resin sheet was in contact with the lower clad layer, and the two were laminated using a vacuum laminator ("VP160" manufactured by Nikko Materials Co., Ltd.) to form a resin composition layer on the lower clad layer. The lamination conditions were the same as those used to laminate the 5 μm-thick resin sheet onto intermediate laminate I. This resulted in Sample B, which included, in this order, a copper-clad laminate, a lower clad layer, and a 50 μm line layer (a layer formed from the cured resin composition).

[0234] -Evaluation of developability- The obtained samples A and B were observed with a scanning electron microscope (SEM) (magnification 2000x) and the minimum fine line width (the width of the smallest line layer that was formed) was measured. The aspect ratio was calculated by dividing the line layer thickness by the minimum fine line width, and the developability was evaluated according to the following evaluation criteria. The line width refers to the width of the line layer. ◯: A line having a line width of 5 μm at a thickness of 5 μm was formed, and a line having a line width of 50 μm at a thickness of 50 μm was formed. Δ: Either a line having a line width of 5 μm at a thickness of 5 μm or a line having a line width of 50 μm at a thickness of 50 μm could not be formed. ×: A line having a line width of 5 μm at a thickness of 5 μm could not be formed, and a line having a line width of 50 μm at a thickness of 50 μm could not be formed.

[0235] (Flame retardancy evaluation) -Preparation of test substrate- 1. Formation of the lower cladding layer The protective film was peeled off from a resin sheet having a 20 μm-thick resin composition layer produced using the resin composition of Production Example 2. The resin sheet was placed on a copper-clad laminate so that the resin composition layer and the copper-clad laminate were in contact, and the laminate was laminated using a vacuum laminator (Nikko Materials Co., Ltd., "VP160"). The lamination conditions were a vacuum time of 30 seconds, a pressure temperature of 60°C, a pressure of 0.3 MPa, and a pressure time of 30 seconds. The support was then peeled off, and the laminate was exposed to UV light using a projection exposure system (Ushio Inc., "UFX-2240") at an exposure energy sufficient to result in 8 gloss-remaining steps on a 41-step tablet. After exposure, the laminate was irradiated with UV light at 2 J / cm². The intermediate laminate II was placed in a clean oven and heated from room temperature to 190°C. After reaching 190°C, it was heated for 90 minutes in a nitrogen atmosphere to cure the resin composition layer. A lower clad layer was formed by curing the resin composition layer, and an intermediate laminate II comprising a copper-clad laminate and a lower clad layer was obtained.

[0236] 2. Formation of the core layer The protective film was peeled off from a resin sheet having a 5 μm-thick resin composition layer produced using the resin composition of Production Example 1. A resin sheet was placed on the surface of the lower clad layer of intermediate laminate II so that the resin composition layer and the lower clad layer of intermediate laminate II were in contact with each other, and laminated using a vacuum laminator (Nikko Materials Co., Ltd., "VP160"). The lamination conditions were a vacuum time of 30 seconds, a pressure temperature of 60°C, a pressure of 0.3 MPa, and a pressure time of 30 seconds. The support was then peeled off, and the sheet was exposed to ultraviolet light using a projection exposure system (Ushio Inc., "UFX-2240") at an exposure energy sufficient to result in 8 gloss-remaining steps on a 41-step tablet. The exposure was performed using a quartz glass mask with a mask pattern capable of drawing multiple straight lines with a line / space ratio of 5 μm / 100 μm and a length of 5 cm. In the L / S of this quartz glass mask, the lines correspond to the width of the core layers, and the spaces correspond to the spacing between the core layers. After the exposure, the film was left to stand at room temperature for 30 minutes, and then the support was peeled off. The entire surface of the resin composition layer was spray-developed with a 1% by mass aqueous solution of tetramethylammonium at 23°C as a developer at a spray pressure of 0.2 MPa for 1 minute. After the spray development, 2 J / cm 2 Thereafter, the substrate was placed in a clean oven, and the temperature was raised from room temperature to 190°C, and after the temperature reached 190°C, a heat treatment was carried out for 90 minutes in a nitrogen atmosphere to cure the resin composition layer.

[0237] A core layer was formed by curing the resin composition layer, and an intermediate laminate III was obtained which had a copper-clad laminate, a lower clad layer, and a core layer in this order.

[0238] 3. Formation of upper cladding layer The protective film was peeled off from a resin sheet having a 20 μm-thick resin composition layer produced using the resin composition of Production Example 2. The resin sheet was placed on the core layer of intermediate laminate III so that the resin composition layer and the core layer were in contact, and laminated using a batch-type vacuum pressure laminator (Nikko Materials Co., Ltd., two-stage build-up laminator, CVP700). The lamination conditions were a vacuum time of 30 seconds, a pressure temperature of 60°C, a pressure of 0.3 MPa, and a pressure time of 30 seconds. The support was then peeled off, and ultraviolet light exposure was performed using a projection exposure device (Ushio Inc., "UFX-2240") at an exposure energy such that the number of glossy remaining steps of a 41-step tablet was 8. After exposure, the UV exposure was 2 J / cm. 2 The sample was then placed in a clean oven, heated from room temperature to 170°C, and after reaching 170°C, heated for 60 minutes in a nitrogen atmosphere to cure the resin composition layer. An upper clad layer was formed by curing the resin composition layer, and a sample laminate was obtained which included a copper-clad laminate, a lower clad layer, a core layer, and an upper clad layer in this order.

[0239] In this sample laminate, the combination of the lower cladding layer and the upper cladding layer constituted the cladding layer. Thus, an optical waveguide was obtained, including the cladding layer and the core layer within the cladding layer. Furthermore, in this sample laminate, the core layer had a 5 cm long linear pattern corresponding to the mask pattern of the quartz glass mask. The width (line width) and spacing (space) of the core layer within these patterns matched the width (line width) and spacing (space) of the mask pattern. The resulting laminate (approximately 360 μm thick) was cut into a 12.7 mm × 127 mm piece with an edge of 1.27 mm. The cut piece was then placed in an oven at 70±1°C for 168 hours and then allowed to cool in a desiccator for at least 4 hours to obtain a test specimen.

[0240] According to the UL-94V flame retardancy test, the burner was moved directly below the test piece, and the flame was applied to the center of the bottom edge of the test piece for 10 seconds, and the subsequent burning time was measured. The flame was again applied to the test piece for 10 seconds, and the subsequent burning time was measured. This was repeated five times, and the test piece was evaluated based on the following criteria. ○: No burning material fell, no test piece was completely burned, and the test piece burned for less than 50 seconds. △: No burning material fell off, no test piece was completely burned, and the test piece burned for 50 to 250 seconds. ×: Combustion object falls, the test piece is completely burned, or the test piece burns for more than 250 seconds.

[0241] (Optical transmission loss measurement) -Preparation of test substrate- 1. Formation of the lower cladding layer The protective film was peeled off from a resin sheet having a 10 μm-thick resin composition layer produced using the resin composition of Production Example 2. The resin sheet was placed on a copper-clad laminate so that the resin composition layer and the copper-clad laminate were in contact, and the laminate was laminated using a vacuum laminator (Nikko Materials Co., Ltd., "VP160"). The lamination conditions were a vacuum time of 30 seconds, a pressure temperature of 60°C, a pressure of 0.3 MPa, and a pressure time of 30 seconds. The support was then peeled off, and the laminate was exposed to UV light using a projection exposure system (Ushio Inc., "UFX-2240") at an exposure energy sufficient to result in 8 gloss-remaining steps on a 41-step tablet. After exposure, the laminate was irradiated with UV light at 2 J / cm². The intermediate laminate II was placed in a clean oven and heated from room temperature to 190°C. After reaching 190°C, it was heated for 90 minutes in a nitrogen atmosphere to cure the resin composition layer. A lower clad layer was formed by curing the resin composition layer, and an intermediate laminate II comprising a copper-clad laminate and a lower clad layer was obtained.

[0242] 2. Formation of the core layer The protective film was peeled off from a resin sheet having a 5 μm-thick resin composition layer produced using the resin composition of Production Example 1. A resin sheet was placed on the surface of the lower clad layer of intermediate laminate II so that the resin composition layer and the lower clad layer of intermediate laminate II were in contact with each other, and laminated using a vacuum laminator (Nikko Materials Co., Ltd., "VP160"). The lamination conditions were a vacuum time of 30 seconds, a pressure temperature of 60°C, a pressure of 0.3 MPa, and a pressure time of 30 seconds. The support was then peeled off, and the sheet was exposed to ultraviolet light using a projection exposure system (Ushio Inc., "UFX-2240") at an exposure energy sufficient to result in 8 gloss-remaining steps on a 41-step tablet. The exposure was performed using a quartz glass mask with a mask pattern capable of drawing multiple straight lines with a line / space ratio of 5 μm / 100 μm and a length of 5 cm. In the L / S of this quartz glass mask, the lines correspond to the width of the core layers, and the spaces correspond to the spacing between the core layers. After the exposure, the film was left to stand at room temperature for 30 minutes, and then the support was peeled off. The entire surface of the resin composition layer was spray-developed with a 1% by mass aqueous solution of tetramethylammonium at 23°C as a developer at a spray pressure of 0.2 MPa for 1 minute. After the spray development, 2 J / cm 2 Thereafter, the substrate was placed in a clean oven, and the temperature was raised from room temperature to 190°C, and after the temperature reached 190°C, a heat treatment was carried out for 90 minutes in a nitrogen atmosphere to cure the resin composition layer.

[0243] A core layer was formed by curing the resin composition layer, and an intermediate laminate III was obtained which had a copper-clad laminate, a lower clad layer, and a core layer in this order.

[0244] 3. Formation of upper cladding layer The protective film was peeled off from a resin sheet having a 20 μm-thick resin composition layer produced using the resin composition of Production Example 2. The resin sheet was placed on the core layer of intermediate laminate III so that the resin composition layer and the core layer were in contact, and laminated using a batch-type vacuum pressure laminator (Nikko Materials Co., Ltd., two-stage build-up laminator, CVP700). The lamination conditions were a vacuum time of 30 seconds, a pressure temperature of 60°C, a pressure of 0.3 MPa, and a pressure time of 30 seconds. The support was then peeled off, and ultraviolet light exposure was performed using a projection exposure device (Ushio Inc., "UFX-2240") at an exposure energy such that the number of glossy remaining steps of a 41-step tablet was 8. After exposure, the UV exposure was 2 J / cm. 2 The sample was then placed in a clean oven, heated from room temperature to 170°C, and after reaching 170°C, heated for 60 minutes in a nitrogen atmosphere to cure the resin composition layer. An upper clad layer was formed by curing the resin composition layer, and a sample laminate was obtained which included a copper-clad laminate, a lower clad layer, a core layer, and an upper clad layer in this order.

[0245] In this sample stack, the combination of the lower cladding layer and the upper cladding layer constituted the cladding layer. Thus, an optical waveguide was obtained that included the cladding layer and a core layer within the cladding layer. Furthermore, in this sample stack, the core layer had a linear pattern 5 cm long that corresponded to the mask pattern of the quartz glass mask, and the width (line width) and spacing (space) of the core layer included in these patterns matched the width (line width) and spacing (space) of the mask pattern.

[0246] From the sample laminates manufactured using the resin sheets of the examples and comparative examples, the portion where the core layer was formed, i.e., the core layer on which a 5 cm linear pattern was drawn and the surrounding clad layer, were cut out to obtain test substrates equipped with optical transmission paths. The cutting conditions were as follows: Dicing equipment: DAD3221 (Disco) Blade: ZH14-SD4000-VI-50 Spindle speed: 30K / min Cutting speed: 5mm / sec Blade height: 0.060mm Dicing tape: T-80W (Denka, 80um)

[0247] (Measurement of optical transmission loss of a calibration optical system) The transmission loss of an optical system configured by excluding the test substrate and the light-collecting module from the optical system for measuring the transmission loss of the test substrate described below was measured. That is, a light source (1310 nm light source, THORLABS "LPSC-1310-FC") and a photoreceiver (Keysight optical power meter "N7742") were connected via an optical fiber (input fiber) on a vibration-isolating table covered with a blackout curtain to obtain an optical system for calibration. The light source was turned on, and the intensity of the light entering the photoreceiver was measured with the photoreceiver, thereby measuring the loss of this optical system for calibration.

[0248] (Optical transmission loss measurement) A test substrate was placed on a vibration-isolating table covered with a blackout curtain. A focusing module (numerical aperture 0.18) was connected to one end (input end) of the test substrate's optical waveguide. A light source (1310 nm light source, THORLABS "LPSC-1310-FC") was then connected to the focusing module via an optical fiber (input fiber). Another focusing module (numerical aperture 0.18) was connected to the other end (output end) of the test substrate's optical waveguide. A light receiver (Keysight optical power meter "N7742") was then connected to the focusing module via an optical fiber (output fiber). This procedure resulted in an optical system in which light emitted from the light source passed through the optical fiber (input fiber), focusing module, optical waveguide, focusing module, and optical fiber (output fiber) in that order before entering the light receiver. Hereinafter, this optical system will be referred to as the "sample optical system." The light source was turned on and the intensity of the light that entered the receiver was measured by the receiver to measure the loss of the sample optical system.

[0249] The loss of the optical waveguide included in the test substrate was determined by subtracting the loss of the calibration optical system from the loss of the sample optical system.

[0250] (Measurement of optical transmission loss (dB / cm) of optical waveguide before high temperature storage test (HTS test)) After measuring the loss of an optical waveguide having a core layer with a 5 cm long linear pattern, it was cut to a length of 4 cm and the same measurement was performed. It was then cut to a length of 3 cm and the same measurement was performed, and measurements were calculated for each of the 5 cm, 4 cm, and 3 cm long optical waveguides. The measurement results were then plotted on a coordinate system with the optical waveguide length on the horizontal axis and the optical waveguide loss on the vertical axis to obtain three coordinates representing the measurement results. An approximation line between these three points was calculated using the least squares method, and the slope of the approximation line was calculated as the loss per unit distance of the optical waveguide (optical transmission loss), and evaluated according to the following evaluation criteria. ◎: Loss value is 0.4dB / cm or less 〇: Loss value is 0.5dB / cm or less △: Loss value is 0.7dB / cm or less ×: Loss value is 1.0 dB / cm or less

[0251] (Measurement of optical transmission loss (dB / cm) of optical waveguide after high temperature storage test (HTS test)) A test substrate was prepared in addition to the test substrate used above, and left in an oven heated to 150°C for 1000 hours. The same procedure was repeated to calculate the transmission loss value after the heat resistance test. The rate of change (%) of the calculated optical transmission loss value after the heat resistance test from the optical transmission loss value before the test was calculated and evaluated according to the following evaluation criteria. ◎: Change rate less than 15% ○: Change rate less than 20% △: Change rate is 20% or more but less than 30% ×: Change rate 30% or more

[0252] <Numerical aperture (NA) measurement> The numerical aperture (NA) of the optical waveguide was calculated by the following formula (1): core represents the refractive index of the cured product of the core resin composition, and n clad represents the refractive index of the cured product of the cladding resin composition.

number

[0253] <Measurement of difference in shrinkage rate> The difference between the shrinkage percentage of the core layer resin composition and the shrinkage percentage of the cladding layer resin composition (shrinkage percentage of the cladding layer resin composition - shrinkage percentage of the core layer resin composition) was calculated, and the absolute value was calculated.

[0254] <Examples 2 to 10 and Comparative Examples 1 to 3> Developability, flame retardancy, optical transmission loss, and optical transmission loss after a heat resistance test were measured in the same manner as in Example 1, except that the core layer and the clad layer were prepared using resin sheets produced using the resin compositions of the Production Examples shown in the table below.

[0255] [Table 2]

[0256] In each example, it was confirmed that even when components (F) to (G) were not contained, the same results as in the above examples were obtained, although to a different extent. [Explanation of symbols]

[0257] 10 Optical waveguide 100 Core Layer 110 Second composition layer 111 Exposure section 112 Unexposed area 200 cladding layers 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 Base material 400 masks 410 Translucent part 420 Light blocking section

Claims

1. A photosensitive resin composition set including a core resin composition and a clad resin composition, The core resin composition and the clad resin composition each comprise: (A) a resin containing a carboxyl group, (B) an epoxy resin; (C) photocurable resin, (D) a photopolymerization initiator, and (E) one or more flame retardants selected from phosphate ester compounds and phosphazene compounds, The content (mass%) of component (E) in the clad resin composition is defined as E when the nonvolatile components of the clad resin composition are defined as 100 mass%. ｃｌａｄ The content (mass%) of component (E) in the core resin composition is defined as E when the non-volatile components of the core resin composition are defined as 100 mass%. ｃｏｒｅ When this is done, E ｃｌａｄ -E ｃｏｒｅ A photosensitive resin composition set in which the value of

2. 2. The photosensitive resin composition set according to claim 1, wherein the phosphate ester compound in the component (E) includes either a compound represented by the following formula (E-1) or a compound represented by the following formula (E-2): 【Chemistry 1】 In formula (E-1), R １ ~R ２０ each independently represents a hydrogen atom, a hydroxy group, or an alkyl group having 1 to 6 carbon atoms which may have a substituent; W １ represents a group represented by formula (E-1a) or a group represented by formula (E-1b). In formula (E-1b), R represents an oxygen atom or a divalent hydrocarbon group having 1 to 20 carbon atoms which may have a substituent. In formula (E-2), R ２１ ~R ２８ each independently represents a hydrogen atom, a hydroxy group, or an alkyl group having 1 to 6 carbon atoms which may have a substituent; R ２９ represents a (meth)acryloyl group, an oxygen atom, a divalent hydrocarbon group having 1 to 10 carbon atoms which may have a substituent, a monovalent hydrocarbon group having 1 to 20 carbon atoms which may have a substituent, or a monovalent group consisting of a combination thereof.

3. The photosensitive resin composition set according to claim 1, wherein the phosphazene compound in the component (E) has a compound represented by the following formula (E-3): 【Chemistry 2】 (In formula (E-3), R ３１ and R ３２ each independently represents a hydrogen atom, a hydroxy group, or an alkyl group having 1 to 6 carbon atoms which may have a substituent; n represents an integer of 3 to 25; and m1 and m2 each independently represent an integer of 0 to 5.

4. 2. The photosensitive resin composition set according to claim 1, wherein the content of phosphorus atoms in the core resin composition is 0.01% by mass or more and 10% by mass or less, when the non-volatile components of the core resin composition are 100% by mass.

5. 2. The photosensitive resin composition set according to claim 1, wherein the content of phosphorus atoms in the clad resin composition is 0.01% by mass or more and 10% by mass or less, when the non-volatile components of the clad resin composition are 100% by mass.

6. The photosensitive resin composition set according to claim 1 , wherein component (A) comprises at least one of an aralkyl resin, a naphthol aralkyl resin, and a cardo resin.

7. The content of component (A) when the nonvolatile components of the core resin composition are taken as 100% by mass is A ｃｏｒｅ The content of component (B) when the non-volatile components of the core resin composition are taken as 100% by mass is defined as B ｃｏｒｅ When this is done, A ｃｏｒｅ / B ｃｏｒｅ The photosensitive resin composition set according to claim 1 , wherein the ratio is 0.3 or more and 5 or less.

8. The content of component (A) when the nonvolatile components of the core resin composition are taken as 100% by mass is A ｃｏｒｅ The content of component (C) when the nonvolatile components of the core resin composition are taken as 100% by mass is defined as C ｃｏｒｅ When this is done, A ｃｏｒｅ / C ｃｏｒｅ The photosensitive resin composition set according to claim 1 , wherein is 0.1 or more and 3 or less.

9. The content of component (A) when the nonvolatile components of the clad resin composition are taken as 100% by mass is A ｃｌａｄ The content of component (B) when the nonvolatile components of the clad resin composition are taken as 100% by mass is defined as B ｃｌａｄ When this is done, A ｃｌａｄ / B ｃｌａｄ The photosensitive resin composition set according to claim 1 , wherein the ratio is 0.3 or more and 5 or less.

10. The content of component (A) when the nonvolatile components of the clad resin composition are taken as 100% by mass is A ｃｌａｄ The content of component (C) when the nonvolatile components of the clad resin composition are taken as 100% by mass is defined as C ｃｌａｄ When this is done, A ｃｌａｄ / C ｃｌａｄ The photosensitive resin composition set according to claim 1 , wherein is 0.1 or more and 3 or less.

11. The photosensitive resin composition set according to claim 1, which is a photosensitive resin composition set for producing an optical waveguide.

12. The photosensitive resin composition set according to claim 1, which is a photosensitive resin composition set for producing an optical waveguide capable of transmitting light having a wavelength of 1300 nm to 1320 nm.

13. The photosensitive resin composition set according to claim 1, which is a photosensitive resin composition set for producing a single-mode optical waveguide.

14. A photosensitive resin sheet set including a core resin sheet and a clad resin sheet, The core resin sheet comprises a resin composition layer containing the core resin composition in the photosensitive resin composition set according to any one of claims 1 to 13, A photosensitive resin sheet set, wherein the clad resin sheet comprises a resin composition layer containing the clad resin composition in the photosensitive resin composition set according to any one of claims 1 to 13.

15. An optical waveguide having a core layer and a clad layer, The core layer, (A) a resin containing a carboxyl group, (B) an epoxy resin; (C) photocurable resin, (D) a photopolymerization initiator, and (E) one or more flame retardants selected from a phosphate ester compound and a phosphazene compound, The cladding layer is (A) a resin containing a carboxyl group, (B) an epoxy resin; (C) photocurable resin, (D) a photopolymerization initiator, and (E) one or more flame retardants selected from a phosphate ester compound and a phosphazene compound, The content (mass%) of component (E) in the clad resin composition is defined as E when the nonvolatile components of the clad resin composition are defined as 100 mass%. ｃｌａｄ The content (mass%) of component (E) in the core resin composition is defined as E when the non-volatile components of the core resin composition are defined as 100 mass%. ｃｏｒｅ When this is done, E ｃｌａｄ -E ｃｏｒｅ An optical waveguide in which the value satisfies 0.6 or more and 12 or less.

16. An optical / electrical hybrid board comprising the optical waveguide according to claim 15.

17. forming a first composition layer containing a cladding resin composition; curing the first composition layer; forming a second composition layer containing a core resin composition on the first composition layer; a step of exposing the second composition layer to light; a step of subjecting the second composition layer to a development treatment; curing the second composition layer; forming a third composition layer containing a cladding resin composition on the second composition layer; and curing the third composition layer in this order, The core resin composition and the clad resin composition each comprise: (A) a resin containing a carboxyl group, (B) an epoxy resin; (C) photocurable resin, (D) a photopolymerization initiator, and (E) one or more flame retardants selected from phosphate ester compounds and phosphazene compounds, The content (mass%) of component (E) in the clad resin composition is defined as E when the nonvolatile components of the clad resin composition are defined as 100 mass%. ｃｌａｄ The content (mass%) of component (E) in the core resin composition is defined as E when the non-volatile components of the core resin composition are defined as 100 mass%. ｃｏｒｅ When this is done, E ｃｌａｄ -E ｃｏｒｅ A method for manufacturing an optical waveguide, wherein the value satisfies 0.6 to 12.

18. forming a first composition layer containing a cladding resin composition; curing the first composition layer; forming a second composition layer containing a core resin composition on the first composition layer; a step of exposing the second composition layer to light; a step of subjecting the second composition layer to a development treatment; curing the second composition layer; forming a third composition layer containing a cladding resin composition on the second composition layer; and curing the third composition layer in this order, The core resin composition and the clad resin composition each comprise: (A) a resin containing a carboxyl group, (B) an epoxy resin; (C) photocurable resin, (D) a photopolymerization initiator, and (E) one or more flame retardants selected from phosphate ester compounds and phosphazene compounds, The content (mass%) of component (E) in the clad resin composition is defined as E when the nonvolatile components of the clad resin composition are defined as 100 mass%. ｃｌａｄ The content (mass%) of component (E) in the core resin composition is defined as E when the non-volatile components of the core resin composition are defined as 100 mass%. ｃｏｒｅ When this is done, E ｃｌａｄ -E ｃｏｒｅ A method for manufacturing an optical / electrical hybrid board, wherein

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