Method for manufacturing optical waveguide

Abstract

Provided is a method for manufacturing, using a thermosetting resin, an optical waveguide having excellent dimensional stability. This method for manufacturing an optical waveguide (10) comprises, in the following order: (i) a step for forming metal wiring patterns (310) on a metal layer (302) of a substrate (first substrate) (300) with the metal layer; (ii) a step for forming a first resin composition layer (210) using a cladding resin composition, and curing the first resin composition layer to form a first cladding layer (211); (iii) a step for removing a substrate part (301) of the first substrate (300); (iv) a step for removing the metal layer (302) and the wiring patterns (310) to form recesses corresponding to the wiring patterns (310); (v) a step for forming a second resin composition layer (110) using a core resin composition containing a thermosetting resin, and curing the second resin composition layer to form a core underlayer (111); (vi) a step for removing a portion of the core underlayer to form a core layer (100); and (vii) a step for forming a third resin composition layer (220) using a cladding resin composition, and curing the third resin composition layer to form a second cladding layer (221).

Description

Optical waveguide manufacturing method

[0001] The present invention relates to a method for manufacturing an optical waveguide.

[0002] In recent years, research into optical signal transmission has been actively conducted with a view to large-capacity information transmission. As this research progresses, it is expected that conventional electronic circuits will be gradually replaced by optical circuits. Therefore, photonic-electronic circuits (CPOs), which combine optical and electrical circuits, are seen as promising.

[0003] To achieve high-speed transmission, a single-mode optical waveguide is desirable as an optical waveguide for forming an optical circuit, and dimensional stability (stability of pattern shape) is required for single-mode optical waveguides (Patent Documents 1 and 2).

[0004] JP 2018-059955 A JP 2018-045031 A

[0005] An optical waveguide is manufactured by providing a plurality of cores, which are optical transmission paths, at predetermined intervals within a cladding. In manufacturing methods for optical waveguides, from the viewpoint of efficiently forming optical waveguides having fine patterns by providing cores with fine line widths at predetermined intervals, optical waveguides are generally manufactured using a cured product of a photosensitive resin composition containing a photocurable resin. However, when a photocurable resin is blended to form a fine pattern, the mechanical strength may become unstable, potentially increasing the transmission loss of the optical waveguide. Therefore, the present inventors attempted to form a fine pattern in an optical waveguide using a thermosetting resin, which has excellent mechanical strength.

[0006] Specifically, the inventors investigated a technique for forming trenches (grooves) in a cladding by laser processing the cladding and then forming cores in the trenches, using a thermosetting resin to provide cores with fine linewidths at predetermined intervals within the cladding. However, the inventors found that forming trenches in a cladding by laser processing can have problems, such as: 1) difficulty in obtaining a trench with the desired shape, such as a non-rectangular cross-sectional shape; 2) difficulty in achieving a constant trench depth by laser processing, resulting in non-uniform trench depth in the direction of extension of the trench; and 3) roughness of the trench bottom. The inventors found that because the resulting core has a shape corresponding to the trench, the technique using trench formation by laser processing described above is difficult to form a core with the desired cross-sectional shape and desired thickness in the direction of extension. The inventors also found that the technique using trench formation by laser processing described above results in a core with a rough interface with the cladding. As described above, according to the inventors' investigations, when they attempted to form an optical waveguide having a fine pattern using a thermosetting resin, they found that it was difficult to form a uniform pattern shape and that the dimensional stability was poor.

[0007] The present invention has been made in view of the above, and has as its object to provide a method for manufacturing an optical waveguide that uses a thermosetting resin and has excellent dimensional stability.

[0008] The present inventors have conducted extensive research to solve the above problems. As a result, the present inventors have found that the above-mentioned problems can be solved by a method for manufacturing an optical waveguide, the method comprising, in this order: (i) forming a metal wiring pattern on a metal layer of a substrate (first substrate) with a metal layer; (ii) forming a first resin composition layer from a cladding resin composition so as to be in contact with the metal layer and the wiring pattern, and curing the first resin composition layer to form a first cladding layer; (iii) removing a substrate portion of the first substrate; (iv) removing the metal layer and the wiring pattern, and forming a recess corresponding to the wiring pattern; (v) forming a second resin composition layer from a core resin composition containing a thermosetting resin so as to be in contact with the recess, and curing the second resin composition layer to form a core underlayer; (vi) removing a portion of the core underlayer and forming a core layer; and (vii) forming a third resin composition layer from a cladding resin composition so as to be in contact with the core layer and the first cladding layer, and curing the third resin composition layer to form a second cladding layer. That is, the present invention includes the following.

[0009] <1> A method for manufacturing an optical waveguide, comprising, in this order: (i) a step of forming a metal wiring pattern on a metal layer of a substrate (first substrate) with a metal layer; (ii) a step of forming a first resin composition layer from a cladding resin composition so as to be in contact with the metal layer and the wiring pattern, and curing the first resin composition layer to form a first cladding layer; (iii) a step of removing a substrate portion of the first substrate; (iv) a step of removing the metal layer and the wiring pattern, and forming a recess corresponding to the wiring pattern; (v) a step of forming a second resin composition layer from a core resin composition containing a thermosetting resin so as to be in contact with the recess, and curing the second resin composition layer to form a core underlayer; (vi) a step of removing a portion of the core underlayer and forming a core layer; and (vii) a step of forming a third resin composition layer from a cladding resin composition so as to be in contact with the core layer and the first cladding layer, and curing the third resin composition layer to form a second cladding layer. <2> The manufacturing method according to <1>, wherein step (ii) comprises: (ii-1) bonding a support (second substrate) to the first resin composition layer on the surface of the first resin composition layer opposite to the metal layer-attached substrate (first substrate). <3> The manufacturing method according to <2>, wherein, after step (vii), it further comprises: (viii) removing the support (second substrate). <4> The manufacturing method according to <2> or <3>, wherein the support (second substrate) is a glass substrate, a single crystal silicon substrate, or a silicon substrate provided with an inorganic film, and the silicon substrate provided with an inorganic film comprises an inorganic film including a silicon oxide film on the surface to be bonded to the first resin composition layer. <5> The manufacturing method according to any one of <1> to <4>, wherein the metal layer portion of the metal layer-attached substrate (first substrate) contains copper. <6> The manufacturing method according to any one of <1> to <5>, wherein step (iv) comprises: (iv-1) removing the metal layer and the wiring pattern by wet treatment using an etching solution to form a recess.<7> The manufacturing method according to any one of <1> to <6>, wherein the substrate portion of the metal layer-attached substrate (first substrate) is a glass substrate, a single crystal silicon substrate, or a silicon substrate provided with an inorganic film, and the silicon substrate provided with an inorganic film has an inorganic film, including a silicon oxide film, between the metal layer and the silicon substrate. <8> The manufacturing method according to any one of <1> to <7>, wherein step (iii) includes: (iii-1) peeling off the substrate portion of the first substrate. <9> The manufacturing method according to any one of <1> to <7>, wherein step (iii) includes: (iii-2) polishing the substrate portion of the first substrate. <10> The manufacturing method according to any one of <1> to <9>, wherein step (vi) includes: (vi-1) polishing a part of the core underlayer by chemical mechanical polishing (CMP) to form a core layer. <11> The manufacturing method according to any one of <1> to <10>, wherein the cladding resin composition contains a thermosetting resin. <12> The manufacturing method according to any one of <1> to <11>, further comprising, after step (i) and before step (ii), a step (ii') of planarizing the surface of the wiring pattern by chemical mechanical polishing (CMP). <13> The manufacturing method according to any one of <1> to <12>, wherein the width of the core layer is 10 μm or less. <14> The manufacturing method according to any one of <1> to <13>, wherein the manufactured optical waveguide is a single-mode optical waveguide. <15> The refractive index of the cured product of the core resin composition at a wavelength of 1310 nm is n. ｃｏｒｅ The refractive index of the cured product of the cladding resin composition is n ｃｌａｄ In this case, n ｃｏｒｅ -n ｃｌａｄ<1> <17> The method for producing an optical waveguide according to any one of <1> to <16>, wherein the core resin composition contains one or more resins selected from the group consisting of epoxy resins, (meth)acrylic resins, phenolic resins, and silicone resins. <18> An optical-electrical hybrid substrate comprising an optical waveguide produced by the method according to any one of <1> to <17>. <19> A semiconductor device comprising the optical-electrical hybrid substrate according to <18>.

[0010] According to the present invention, a method for producing an optical waveguide having excellent dimensional stability can be provided by using a thermosetting resin.

[0011] FIG. 1 is a perspective view schematically illustrating an optical waveguide manufactured by the manufacturing method of the present invention. FIG. 2 is a schematic cross-sectional view illustrating step (i) of the manufacturing method of an optical waveguide of the present invention. FIG. 3 is a schematic cross-sectional view illustrating step (i-1) according to one embodiment of the manufacturing method of an optical waveguide of the present invention. FIG. 4 is a schematic cross-sectional view illustrating step (i-2) according to one embodiment of the manufacturing method of an optical waveguide of the present invention. FIG. 5 is a schematic cross-sectional view illustrating a portion of step (ii) of the manufacturing method of an optical waveguide of the present invention. FIG. 6 is a schematic cross-sectional view illustrating a portion of step (ii) of the manufacturing method of an optical waveguide of the present invention. FIG. 7 is a schematic cross-sectional view illustrating step (iii) of the manufacturing method of an optical waveguide of the present invention. FIG. 8 is a schematic cross-sectional view illustrating step (iv) of the manufacturing method of an optical waveguide of the present invention. FIG. 9 is a schematic cross-sectional view illustrating a portion of step (v) of the manufacturing method of an optical waveguide of the present invention. FIG. 10 is a schematic cross-sectional view illustrating a portion of step (v) of the manufacturing method of an optical waveguide of the present invention. Fig. 11 is a schematic cross-sectional view illustrating step (vi) of the method for producing an optical waveguide of the present invention. Fig. 12 is a schematic cross-sectional view illustrating a part of step (vii) of the method for producing an optical waveguide of the present invention. Fig. 13 is a schematic cross-sectional view illustrating a part of step (vii) of the method for producing an optical waveguide of the present invention.

[0012] The present invention will be described in detail below with reference to embodiments and examples. However, the present invention is not limited to the following embodiments and examples, and can be implemented with any modifications within the scope of the claims of the present invention and their equivalents.

[0013] [Resin Composition] Before describing the method for producing an optical waveguide of the present invention in detail, the resin composition used in steps (ii), (v) and (vii) in the method for producing an optical waveguide of the present invention will be described.

[0014] In the method for producing an optical waveguide of the present invention, the resin composition includes a core resin composition and a clad resin composition. The core resin composition refers to a resin composition for forming the core layer of the optical waveguide. The clad resin composition refers to a resin composition for forming the clad layer of the optical waveguide. The production method of the present invention can provide 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.

[0015] <Core Resin Composition> In the method for producing an optical waveguide of the present invention, the core resin composition contains a thermosetting resin.

[0016] The thermosetting resin contained in the core resin composition may be a resin that can be cured when heat is applied. Examples of thermosetting resins include epoxy resins, resins having radical polymerizable groups, phenolic resins, active ester resins, carbodiimide resins, amine resins, acid anhydride resins, benzoxazine resins, cyanate ester resins, thiol resins, and silicone resins. One type of thermosetting resin may be used alone, or two or more types may be used in combination.

[0017] Examples of epoxy resins include bixylenol type epoxy resins, bisphenol A type epoxy resins, bisphenol F type epoxy resins, bisphenol S type epoxy resins, bisphenol AF type epoxy resins, dicyclopentadiene type epoxy resins, trisphenol type epoxy resins, naphthol novolac type epoxy resins, phenol novolac type epoxy resins, tert-butyl-catechol type epoxy resins, naphthalene type epoxy resins, naphthol type epoxy resins, anthracene type epoxy resins, glycidylamine type epoxy resins, glycidyl ester type epoxy resins, cresol novolac 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, cyclohexane dimethanol type epoxy resins, naphthylene ether type epoxy resins, trimethylol type epoxy resins, tetraphenylethane type epoxy resins, glycidyl ether type aliphatic epoxy resins, and glycidyl ether type aromatic epoxy resins. The epoxy resin may be used alone or in combination of two or more kinds.

[0018] The thermosetting resin preferably contains an epoxy resin having two or more epoxy groups per molecule as the epoxy resin. From the viewpoint of significantly achieving the desired effects of the present invention, the amount of the epoxy resin having two or more epoxy groups per molecule is preferably 50% by mass or more, more preferably 60% by mass or more, and even more preferably 70% by mass or more, and usually 100% by mass or less, relative to 100% by mass of the epoxy resin.

[0019] The epoxy resin preferably has an aromatic structure. When two or more epoxy resins are used, it is preferred that at least one of the epoxy resins has an aromatic structure. The aromatic structure is a chemical structure generally defined as aromatic, and includes polycyclic aromatic rings and aromatic heterocycles.

[0020] Epoxy resins include epoxy resins that are liquid at a temperature of 25° C. (hereinafter sometimes referred to as "liquid epoxy resins") and epoxy resins that are solid at a temperature of 25° C. (hereinafter sometimes referred to as "solid epoxy resins"). The resin composition may contain only a liquid epoxy resin as the epoxy resin, only a solid epoxy resin, or a combination of a liquid epoxy resin and a solid epoxy resin.

[0021] The liquid epoxy resin is preferably a liquid epoxy resin having two or more epoxy groups in one molecule.

[0022] Examples of 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 ether type aliphatic epoxy resins, glycidyl ether type aromatic 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, dicyclopentadiene type epoxy resins, and epoxy resins having a butadiene structure.

[0023] Specific examples of liquid epoxy resins include "HP-4032", "HP-4032-D", and "HP-4032-SS" (naphthalene type epoxy resins) manufactured by DIC Corporation; "828US", "828EL", "825", and "Epicoat 828EL" (bisphenol A type epoxy resins) manufactured by Mitsubishi Chemical Corporation; "807" and "1750" (bisphenol F type epoxy resins) manufactured by Mitsubishi Chemical Corporation; and "152" (phenol novolac type epoxy resin) manufactured by Mitsubishi Chemical Corporation. Mitsubishi Chemical Corporation's "630", "630LSD", and "604" (glycidylamine-type epoxy resins); ADEKA Corporation's "ED-523T" (glycirol-type epoxy resin); ADEKA Corporation's "EP-3950L" and "EP-3980S" (glycidylamine-type epoxy resins); ADEKA Corporation's "EP-4088S" (dicyclopentadiene-type epoxy resin); Nippon Steel Chemical & Material Corporation's "ZX1059" (bisphenol A-type epoxy resin and bisphenol A-type epoxy resin). "EX-252" and "EX-721" (glycidyl ester type epoxy resins) manufactured by Nagase ChemteX Corporation; "EHPE3150CE" manufactured by Daicel Corporation, "THI-DE" manufactured by ENEOS Corporation, "Shofree CDMDG" manufactured by Resonac Corporation, "LDO" (alicyclic epoxy resin) manufactured by SYMRISE Corporation; "Celloxide 2021P", "Celloxide 2081P", "Celloxide 2000", and "Celloxide 2021P" manufactured by Daicel Corporation. Examples include "Side 8000" (alicyclic epoxy resin having an 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" manufactured by Nippon Steel Chemical & Material Co., Ltd. (liquid 1,4-glycidylcyclohexane type epoxy resin); and "YX8000" and "YX8034" manufactured by Mitsubishi Chemical Corporation (hydrogenated bisphenol A type epoxy resin). These may be used alone or in combination of two or more.

[0024] The solid epoxy resin is preferably a solid epoxy resin having three or more epoxy groups in one molecule.

[0025] Examples of solid epoxy resins include bixylenol type epoxy resins, naphthalene type epoxy resins, naphthalene type tetrafunctional epoxy resins, naphthol novolac type epoxy resins, cresol novolac type epoxy resins, dicyclopentadiene type epoxy resins, trisphenol type epoxy resins, naphthol type epoxy resins, biphenyl type epoxy resins, naphthylene ether type epoxy resins, anthracene type epoxy resins, bisphenol A type epoxy resins, bisphenol AF type epoxy resins, phenol aralkyl type epoxy resins, tetraphenylethane type epoxy resins, phenolphthalimidine type epoxy resins, and phenolphthalein type epoxy resins.

[0026] 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; "HP-7200", "HP-7200HH", "HP-7200H", and "HP-7200L" (dicyclopentadiene type epoxy resins) manufactured by DIC Corporation; and "EXA-73" manufactured by DIC Corporation. 11", "EXA-7311-G3", "EXA-7311-G4", "EXA-7311-G4S", "HP6000" (naphthylene ether type epoxy resin); "EPPN-502H" (trisphenol type epoxy resin) manufactured by Nippon Kayaku Co., Ltd.; "NC7000L" (naphthol novolac type epoxy resin) manufactured by Nippon Kayaku Co., Ltd.; "NC3000H", "NC3000", "NC3000L", "NC3000FH", "NC3100" (biphenyl type epoxy resin) manufactured by Nippon Kayaku Co., Ltd.; "ESN475V" manufactured by Nippon Steel Chemical & Material Co., Ltd. "," ESN4100V" (naphthalene-type epoxy resin); "ESN485" (naphthol-type epoxy resin) manufactured by Nippon Steel Chemical & Material Co., Ltd.; "ESN375" (dihydroxynaphthalene-type epoxy resin) manufactured by Nippon Steel Chemical & Material Co., Ltd.; "YX4000H", "YX4000", "YX4000HK", "YL7890" (bixylenol-type epoxy resin) manufactured by Mitsubishi Chemical Corporation; "YL6121" (biphenyl-type epoxy resin) manufactured by Mitsubishi Chemical Corporation; "YX8800" (anthracene-type epoxy resin) manufactured by Mitsubishi Chemical Corporation; "YX7700" (phenol aralkyl type epoxy resin) manufactured by Hishi Chemical Co., Ltd.; "PG-100" and "CG-500" manufactured by Osaka Gas Chemicals Co., Ltd.; "YX7760" (bisphenol AF type epoxy resin) manufactured by Mitsubishi Chemical Corporation; "YL7800" (fluorene type epoxy resin) manufactured by Mitsubishi Chemical Corporation; "1010" (bisphenol A type epoxy resin) manufactured by Mitsubishi Chemical Corporation; "1031S" (tetraphenylethane type epoxy resin) manufactured by Mitsubishi Chemical Corporation; "WHR991S" (phenolphthalimidine type epoxy resin) manufactured by Nippon Kayaku Co., Ltd.;Examples include "EHPE3150" manufactured by Daicel Corporation, "DE-102" and "DE-103" manufactured by ENEOS Corporation, and "DCPD-DE" (alicyclic epoxy resin) manufactured by Japan Material Technology Co., Ltd. These may be used alone or in combination of two or more.

[0027] When a solid epoxy resin and a liquid epoxy resin are used in combination as the epoxy resin, the mass ratio of the solid epoxy resin to the liquid epoxy resin (solid epoxy resin / liquid epoxy resin) is not particularly limited, but is preferably 1 or less, more preferably 0.5 or less, even more preferably 0.1 or less, still more preferably 0.05 or less, and particularly preferably 0.01 or less.

[0028] The epoxy equivalent of the epoxy resin is preferably 50 g / eq. to 5000 g / eq., more preferably 50 g / eq. to 3000 g / eq., even more preferably 80 g / eq. to 2000 g / eq., and even more preferably 110 g / eq. to 1000 g / eq. The epoxy equivalent is the mass of the resin per equivalent of epoxy groups. This epoxy equivalent can be measured in accordance with JIS K7236.

[0029] From the viewpoint of significantly achieving the desired effects of the present invention, the weight average molecular weight (Mw) of the epoxy resin is preferably 100 to 5000, more preferably 250 to 3000, and even more preferably 400 to 1500. The weight average molecular weight of the resin can be measured as a polystyrene-equivalent value by gel permeation chromatography (GPC).

[0030] A compound having an ethylenically unsaturated bond can be used as a resin having a radical polymerizable group. Therefore, a resin having a radical polymerizable group can have a radical polymerizable group containing an ethylenically unsaturated bond. Examples of radical polymerizable groups include unsaturated hydrocarbon groups such as vinyl, allyl, 3-cyclohexenyl, 3-cyclopentenyl, 2-vinylphenyl, 3-vinylphenyl, and 4-vinylphenyl; and α,β-unsaturated carbonyl groups such as (meth)acryloyl and maleimide groups (2,5-dihydro-2,5-dioxo-1H-pyrrol-1-yl). The term "(meth)acryloyl group" encompasses acryloyl and methacryloyl groups, as well as combinations thereof. The number of radical polymerizable groups contained in a molecule of a resin having a radical polymerizable group may be one, but preferably two or more. One type of resin having a radical polymerizable group may be used alone, or two or more types may be used in combination.

[0031] Examples of the resin having a radical polymerizable group include a (meth)acrylic resin, an allyl resin, a propenyl resin, a styrene resin, a maleimide resin, etc. Among these, the resin having a radical polymerizable group preferably includes a (meth)acrylic resin.

[0032] The (meth)acrylic resin is, for example, a resin having one or more, preferably two or more, acryloyl groups and / or methacryloyl groups. Examples of the (meth)acrylic resin include cyclohexane-1,4-dimethanol di(meth)acrylate, cyclohexane-1,3-dimethanol di(meth)acrylate, tricyclodecane dimethanol di(meth)acrylate, neopentyl glycol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,8-octanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, and the like. aliphatic (meth)acrylic acid ester compounds having a low molecular weight (molecular weight less than 1000) such as dioxane glycol di(meth)acrylate, 3,6-dioxa-1,8-octanediol di(meth)acrylate, 1,10-decanediol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, trimethylolethane tri(meth)acrylate, glycerin tri(meth)acrylate, and pentaerythritol tetra(meth)acrylate; low molecular weight (molecular weight less than 1000) ether-containing (meth)acrylic acid ester compounds such as bis(3-hydroxypropyl)isocyanurate tri(meth)acrylate, 3,6,9-trioxaundecane-1,11-diol di(meth)acrylate, polyethylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, 9,9-bis[4-(2-acryloyloxyethoxy)phenyl]fluorene, ethoxylated bisphenol A di(meth)acrylate, and propoxylated bisphenol A di(meth)acrylate; low molecular weight (molecular weight less than 1000) isocyanurate-containing (meth)acrylic acid ester compounds such as tris(3-hydroxypropyl)isocyanurate tri(meth)acrylate, tris(2-hydroxyethyl)isocyanurate tri(meth)acrylate, and ethoxylated isocyanuric acid tri(meth)acrylate; and high molecular weight (molecular weight 1000 or more) acrylic acid ester compounds such as (meth)acrylic-modified polyphenylene ether resins.Commercially available (meth)acrylic resins include, for example, "A-DOG" (dioxane glycol diacrylate) manufactured by Shin-Nakamura Chemical Co., Ltd., "DCP-A" (tricyclodecane dimethanol diacrylate) and "DCP" (tricyclodecane dimethanol dimethacrylate) manufactured by Kyoeisha Chemical Co., Ltd., "KAYARAD R-684" (tricyclodecane dimethanol diacrylate) and "KAYARAD R-604" (dioxane glycol diacrylate) manufactured by Nippon Kayaku Co., Ltd., and "SA9000" and "SA9000-111" (methacrylic-modified polyphenylene ether) manufactured by SABIC.

[0033] The allyl resin is, for example, a compound having one or more, preferably two or more, allyl groups. Examples of allyl resins include aromatic carboxylic acid allyl ester compounds such as diallyl diphenate, triallyl trimellitate, diallyl phthalate, diallyl isophthalate, diallyl terephthalate, 2,6-naphthalenedicarboxylic acid diallyl, and 2,3-naphthalenecarboxylic acid diallyl ester compounds; isocyanuric acid allyl ester compounds such as 1,3,5-triallyl isocyanurate and 1,3-diallyl-5-glycidyl isocyanurate; epoxy-containing aromatic allyl compounds such as 2,2-bis[3-allyl-4-(glycidyloxy)phenyl]propane; benzoxazine-containing aromatic allyl compounds such as bis[3-allyl-4-(3,4-dihydro-2H-1,3-benzoxazin-3-yl)phenyl]methane; ether-containing aromatic allyl compounds such as 1,3,5-triallyl ether benzene; allyl silane compounds such as diallyl diphenyl silane; and resins containing a plurality of benzene rings and allyl groups. Commercially available allyl resins include "TAIC" (1,3,5-triallyl isocyanurate) manufactured by Nippon Kasei Chemical Industry Co., Ltd.; "DAD" (diallyl diphenate) manufactured by Nisshoku Techno Fine Chemical Co., Ltd.; "TRIAM-705" (triallyl trimellitate) manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.; "DAND" (2,3-diallyl naphthalenecarboxylate) manufactured by Nisshoku Techno Fine Chemical Co., Ltd.; "RE-810NM" (2,2-bis[3-allyl-4-(glycidyloxy)phenyl]propane) manufactured by Nippon Kayaku Co., Ltd.; "DA-MGIC" (1,3-diallyl-5-glycidyl isocyanurate) manufactured by Shikoku Chemical Industry Co., Ltd.; and "NE-V-1100-70T" (a resin containing a plurality of benzene rings and allyl groups) manufactured by DIC Corporation.

[0034] The propenyl resin is, for example, a compound having one or more, preferably two or more, propenyl groups (1-propenyl groups). The propenyl resin may be a monomer or an oligomer, as long as it has one or more propenyl groups in one molecule. Commercially available propenyl resins include "Petrotax 70" and "Petrotax 90" manufactured by Tosoh Corporation.

[0035] The styrene resin is, for example, a compound having one or more, preferably two or more, vinyl groups directly bonded to an aromatic carbon atom. Examples of the styrene resin include low-molecular-weight (molecular-weight less than 1000) styrene resins such as divinylbenzene, 2,4-divinyltoluene, 2,6-divinylnaphthalene, 1,4-divinylnaphthalene, 4,4'-divinylbiphenyl, 1,2-bis(4-vinylphenyl)ethane, 2,2-bis(4-vinylphenyl)propane, and bis(4-vinylphenyl)ether; and high-molecular-weight (molecular-weight 1000 or more) styrene resins such as vinylbenzyl-modified polyphenylene ether resins and styrene-divinylbenzene copolymers. Commercially available styrene resins include, for example, "ODV-XET (X03)", "ODV-XET (X04)", and "ODV-XET (X05)" (styrene-divinylbenzene copolymers) manufactured by Nippon Steel Chemical & Material Co., Ltd.; and "OPE-2St", "OPE-2St 1200", and "OPE-2St 2200" (vinylbenzyl-modified polyphenylene ether resins) manufactured by Mitsubishi Gas Chemical Company, Inc.

[0036] The maleimide resin is, for example, a compound having one or more, preferably two or more, maleimide groups. The maleimide resin may be an aliphatic maleimide resin containing an aliphatic amine skeleton, or an aromatic maleimide resin containing an aromatic amine skeleton. Commercially available maleimide resins include, for example, "SLK-2600" and "SLK-6895-T90" manufactured by Shin-Etsu Chemical Co., Ltd., "BMI-1500," "BMI-1700," "BMI-3000J," "BMI-689," and "BMI-2500" (dimer diamine structure-containing maleimide resins) manufactured by Designer Molecules Inc., and "BMI-3000J," "BMI-689," and "BMI-2500" (dimer diamine structure-containing maleimide resins) manufactured by Designer Molecules Inc. Examples of the maleimide resin include "BMI-6100" (aromatic maleimide resin) manufactured by Nippon Kayaku Co., Ltd., "MIR-5000-60T" and "MIR-3000-70MT" (biphenylaralkyl maleimide resin) manufactured by Nippon Kayaku Co., Ltd., "BMI-70" and "BMI-80" manufactured by K.I. Chemical Industry Co., Ltd., and "BMI-2300" and "BMI-TMH" manufactured by Daiwa Kasei Kogyo Co., Ltd. Furthermore, as the maleimide resin, the maleimide resin (indane ring skeleton-containing maleimide resin) disclosed in the Japan Institute of Invention and Innovation Disclosure Technical Bulletin No. 2020-500211 may also be used.

[0037] The phenolic resin may be a resin having one or more, preferably two or more, phenolic hydroxyl groups per molecule. The phenolic hydroxyl group refers to a hydroxyl group bonded to an aromatic ring such as a benzene ring or a naphthalene ring. Preferred phenolic resins include biphenyl-type phenolic resins, naphthalene-type phenolic resins, phenol novolac-type phenolic resins, naphthylene ether-type phenolic resins, and triazine skeleton-containing phenolic resins.

[0038] Specific examples of phenolic resins include biphenyl-type phenolic resins "MEH-7700," "MEH-7810," and "MEH-7851" (manufactured by Meiwa Kasei Co., Ltd.), naphthalene-type phenolic resins "NHN," "CBN," and "GPH" (manufactured by Nippon Kayaku Co., Ltd.), "SN170," "SN180," "SN190," "SN475," "SN485," "SN495," "SN375," and "SN395" (manufactured by Nippon Steel Chemical & Material Co., Ltd.), and "EXB9500" (manufactured by DIC Corporation), phenol novolac-type phenolic resin "TD2090" (manufactured by DIC Corporation), and naphthylene ether-type phenolic resin "EXB-6000" (manufactured by DIC Corporation). Specific examples of triazine skeleton-containing phenolic resins include "LA3018," "LA7052," "LA7054," and "LA1356" (manufactured by DIC Corporation).

[0039] As the active ester resin, a resin having one or more active ester groups per molecule can be used. Among these, preferred active ester resins are compounds having two or more highly reactive ester groups per molecule, such as phenol esters, thiophenol esters, N-hydroxyamine esters, and esters of heterocyclic hydroxy compounds. The active ester resin is preferably one obtained by a condensation reaction between a carboxylic acid compound and / or a thiocarboxylic acid compound and a hydroxy compound and / or a thiol compound. From the viewpoint of improving heat resistance in particular, the active ester resin is preferably an active ester resin obtained from a carboxylic acid compound and a hydroxy compound, and more preferably an active ester resin obtained from a carboxylic acid compound and a phenol compound and / or a naphthol compound. Examples of carboxylic acid compounds include benzoic acid, acetic acid, succinic acid, maleic acid, itaconic acid, phthalic acid, isophthalic acid, terephthalic acid, and pyromellitic acid. Examples of phenol compounds or naphthol compounds include hydroquinone, resorcinol, bisphenol A, bisphenol F, bisphenol S, phenolphthalene, methylated bisphenol A, methylated bisphenol F, methylated bisphenol S, phenol, o-cresol, m-cresol, p-cresol, catechol, α-naphthol, β-naphthol, 1,5-dihydroxynaphthalene, 1,6-dihydroxynaphthalene, 2,6-dihydroxynaphthalene, dihydroxybenzophenone, trihydroxybenzophenone, tetrahydroxybenzophenone, phloroglucin, benzenetriol, dicyclopentadiene-type diphenol compounds, phenol novolak, etc. Here, "dicyclopentadiene-type diphenol compounds" refers to diphenol compounds obtained by condensing one dicyclopentadiene molecule with two phenol molecules.

[0040] Commercially available active ester resins include, for example, active ester resins containing a dicyclopentadiene-type diphenol structure such as "EXB9451", "EXB9460", "EXB9460S", "EXB-8000L", "EXB-8000L-65M", "EXB-8000L-65TM", "HPC-8000L-65TM", "HPC-8000", and "HPC-8000-65T" (manufactured by DIC Corporation); and active ester resins containing a naphthalene structure such as "HP-C-8151-62T", "EXB-8100L-65T", "EXB-8150-60T", and "EXB-8150-62T". Examples of such active ester resins include "EXB-9416-70BK," "HPC-8150-62T," and "EXB-8" (manufactured by DIC Corporation); an example of a phosphorus-containing active ester resin is "EXB9401" (manufactured by DIC Corporation); an example of an active ester resin which is an acetylated product of phenol novolac is "DC808" (manufactured by Mitsubishi Chemical Corporation); an example of an active ester resin which is a benzoylated product of phenol novolac is "YLH1026," "YLH1030," and "YLH1048" (manufactured by Mitsubishi Chemical Corporation); and an example of an active ester resin containing a styryl group and a naphthalene structure is "PC1300-02-65MA" (manufactured by Air Water Inc.). One type of active ester resin may be used alone, or two or more types may be used in combination.

[0041] The carbodiimide resin may be a resin having one or more, preferably two or more, carbodiimide structures in one molecule. Examples of the carbodiimide resin include aliphatic biscarbodiimides such as tetramethylene-bis(t-butylcarbodiimide) and cyclohexanebis(methylene-t-butylcarbodiimide); aromatic biscarbodiimides such as phenylene-bis(xylylcarbodiimide); aliphatic polycarbodiimides such as polyhexamethylenecarbodiimide, polytrimethylhexamethylenecarbodiimide, polycyclohexylenecarbodiimide, poly(methylenebiscyclohexylenecarbodiimide), and poly(isophoronecarbodiimide); poly(phenylenecarbodiimide), poly(naphthalenecarbodiimide), and the like. Examples of polycarbodiimides include aromatic polycarbodiimides such as poly(methylenebis(methylphenylene)carbodiimide), poly(tolylenecarbodiimide), poly(methyldiisopropylphenylenecarbodiimide), poly(triethylphenylenecarbodiimide), poly(diethylphenylenecarbodiimide), poly(triisopropylphenylenecarbodiimide), poly(diisopropylphenylenecarbodiimide), poly(xylylenecarbodiimide), poly(tetramethylxylylenecarbodiimide), poly(methylenediphenylenecarbodiimide), and poly[methylenebis(methylphenylene)carbodiimide]. Commercially available carbodiimide resins include, for example, "Carbodilite V-02B," "Carbodilite V-03," "Carbodilite V-04K," "Carbodilite V-07," and "Carbodilite V-09," manufactured by Nisshinbo Chemical Inc.; and "Stavaxol P," "Stavaxol P400," and "Hykasil 510," manufactured by Lanxess AG. One type of carbodiimide resin may be used alone, or two or more types may be used in combination.

[0042] The acid anhydride resin may be a resin having one or more, preferably two or more, acid anhydride groups in one molecule. Examples of the acid anhydride resin include phthalic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, methyltetrahydrophthalic anhydride, methylhexahydrophthalic anhydride, methylnadic anhydride, hydrogenated methylnadic anhydride, trialkyltetrahydrophthalic anhydride, dodecenyl succinic anhydride, 5-(2,5-dioxotetrahydro-3-furanyl)-3-methyl-3-cyclohexene-1,2-dicarboxylic anhydride, trimellitic anhydride, pyromellitic anhydride, and benzophenonetetracarboxylic anhydride. Examples of commercially available acid anhydrides include polymeric acid anhydrides such as styrene-maleic acid resins copolymerized with styrene and maleic acid, ethylene glycol bis(anhydrotrimellitate), styrene hydrate, biphenyltetracarboxylic dianhydride, naphthalenetetracarboxylic dianhydride, oxydiphthalic dianhydride, 3,3'-4,4'-diphenylsulfonetetracarboxylic dianhydride, 1,3,3a,4,5,9b-hexahydro-5-(tetrahydro-2,5-dioxo-3-furanyl)-naphtho[1,2-C]furan-1,3-dione, ethylene glycol bis(anhydrotrimellitate), and "HNA-100", "MH-700", "MTA-15", "DDSA", and "OSA" manufactured by New Japan Chemical Co., Ltd., "YH-306" and "YH-307" manufactured by Mitsubishi Chemical Corporation, and "HN-2200" and "HN-5500" manufactured by Resonac Corporation. The acid anhydride resin may be used alone or in combination of two or more kinds.

[0043] As the amine resin, a resin having one or more, preferably two or more, amino groups per molecule can be used. Examples of the amine resin include aliphatic amines, polyether amines, alicyclic amines, and aromatic amines, with aromatic amines being preferred. The amine resin is preferably a primary amine or a secondary amine, and more preferably a primary amine. Specific examples of the amine resin include 4,4'-methylenebis(2,6-dimethylaniline), 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylsulfone, 3,3'-diaminodiphenylsulfone, m-phenylenediamine, m-xylylenediamine, diethyltoluenediamine, 4,4'-diaminodiphenyl ether, 3,3'-dimethyl-4,4'-diaminobiphenyl, 2,2'-dimethyl-4,4'-diaminobiphenyl, 3,3'-dihydroxybenzidine, and 2,2-bis(3-amino-4-hydroxyphenyl)propanol. Examples of suitable bis(4-aminophenoxy)biphenyl include bis(4-aminophenyl)propane, 3,3-dimethyl-5,5-diethyl-4,4-diphenylmethanediamine, 2,2-bis(4-aminophenyl)propane, 2,2-bis(4-(4-aminophenoxy)phenyl)propane, 1,3-bis(3-aminophenoxy)benzene, 1,3-bis(4-aminophenoxy)benzene, 1,4-bis(4-aminophenoxy)benzene, 4,4'-bis(4-aminophenoxy)biphenyl, bis(4-(4-aminophenoxy)phenyl)sulfone, and bis(4-(3-aminophenoxy)phenyl)sulfone. The amine resin may be a commercially available product, and examples thereof include "SEIKACURE-S" manufactured by Seika Corporation; "KAYABOND C-200S", "KAYABOND C-100", "KAYAHARD A-A", "KAYAHARD A-B", and "KAYAHARD A-S" manufactured by Nippon Kayaku Co., Ltd.; and "Epicure W" manufactured by Mitsubishi Chemical Corporation. One type of amine resin may be used alone, or two or more types may be used in combination.

[0044] The benzoxazine resin may be a resin having one or more, preferably two or more, benzoxazine rings per molecule. Specific examples of the benzoxazine resin include "JBZ-OP100D" and "ODA-BOZ" manufactured by JFE Chemical Corporation; "HFB2006M" manufactured by Showa Highpolymer Co., Ltd.; and "P-d" and "F-a" manufactured by Shikoku Chemicals Corporation. One type of benzoxazine resin may be used alone, or two or more types may be used in combination.

[0045] As the cyanate ester resin, a resin having one or more, preferably two or more, cyanate groups in one molecule can be used. Examples of cyanate ester resins include bifunctional cyanate resins such as bisphenol A dicyanate, polyphenol cyanate (oligo(3-methylene-1,5-phenylene cyanate)), 4,4'-methylenebis(2,6-dimethylphenyl cyanate), 4,4'-ethylidene diphenyl dicyanate, hexafluorobisphenol A dicyanate, 2,2-bis(4-cyanate)phenylpropane, 1,1-bis(4-cyanatephenylmethane), bis(4-cyanate-3,5-dimethylphenyl)methane, 1,3-bis(4-cyanatephenyl-1-(methylethylidene))benzene, bis(4-cyanatephenyl)thioether, and bis(4-cyanatephenyl)ether; polyfunctional cyanate resins derived from phenol novolac and cresol novolac; and prepolymers in which these cyanate resins are partially converted to triazine. Specific examples of cyanate ester resins include "PT30" and "PT60" (both phenol novolac type multifunctional cyanate ester resins) manufactured by Arxada, "BA230" and "BA230S75" (prepolymers in which part or all of bisphenol A dicyanate is triazinated to form a trimer), etc. One type of cyanate ester resin may be used alone, or two or more types may be used in combination.

[0046] Examples of thiol resins include trimethylolpropane tris(3-mercaptopropionate), pentaerythritol tetrakis(3-mercaptobutyrate), tris(3-mercaptopropyl)isocyanurate, etc. One type of thiol resin may be used alone, or two or more types may be used in combination.

[0047] As the silicone resin, a resin having one or more, preferably two or more, silanol groups and / or alkoxysilyl groups in one molecule can be used. Commercially available silicone resins include "KR-220L", "KR-220LP", "KR-242P", "KR-251", "X-40-2406M", "KR-112", "KR-211", "KR-212", "KR-255", "KR-271", "KR-282", "KR-300", "KR-311", "X-48-1030", and "X- 40-2667A”, “X-40-2756”, “KR-480”, “ES-1001N”, “ES-1002T”, “ES-1023”, “X-41-1610”, “KR-520” 6”, “KR-5230”, “KR-5234”, “KR-5235”, “KC-89S”, “KR-515”, “KR-500”, “X-40-9225”, “X-40-9246” , "X-40-9250", "X-88-1004", "X-88-1007", "X-48-1500", "X-48-1600", "KR-401N", "X-40-9227" , "KR-510", "KR-213", "X-40-9312", "KR-4000G", "KR-4000F2", "KR-400", "X-40-2327", "KR-401" Examples of silicone resins include, for example, "X-40-2450", "X-40-9300", "X-40-9301", "KR-517", "X-24-9590", "KR-516", "KR-518", "KR-519", "KR-513", "X-40-9296", "KR-511", "KR-2710", "KR-470", "X-40-2678", and "X-40-2669". One type of silicone resin may be used alone, or two or more types may be used in combination.

[0048] In particular, the core resin composition preferably contains one or more resins selected from the group consisting of epoxy resins, (meth)acrylic resins, phenolic resins, and silicone resins.

[0049] The core resin composition may contain a cyclic carbonate compound as an optional component. The cyclic carbonate compound refers to a compound having a carbonate bond (—O—C(═O)—O—) in a cyclic structure. The cyclic carbonate compound does not include components that fall under the category of the thermosetting resin described above. One type of cyclic carbonate compound may be used alone, or two or more types may be used in combination.

[0050] In the cyclic carbonate compound, the number of atoms forming the cyclic structure is preferably 5 or 6. Therefore, the cyclic carbonate compound is preferably a 5-membered ring cyclic carbonate compound and / or a 6-membered ring cyclic carbonate compound.

[0051] The cyclic carbonate compound may have a substituent. Examples of the substituent that the cyclic carbonate compound may have include a halogen atom, an alkyl group having 1 to 6 carbon atoms which may be substituted with a halogen atom, an alkenyl group having 2 to 6 carbon atoms which may be substituted with a halogen atom, and an alkynyl group having 2 to 6 carbon atoms which may be substituted with a halogen atom.

[0052] As the cyclic carbonate compound, commercially available products may be used, and examples thereof include "DXC" (5,5-dimethyl-4-(propan-2-yl)-1,3-dioxan-2-one) and "DEDPO" (5,5-diethyl-1,3-dioxan-2-one) manufactured by JNC Corporation; and "ethylene carbonate" (1,3-dioxolan-2-one) manufactured by Tokyo Chemical Industry Co., Ltd.

[0053] The core resin composition may contain a heat curing accelerator as an optional component. The heat curing accelerator functions, for example, as a catalyst or a thermal radical generator, thereby accelerating the reaction of the thermosetting resin and accelerating the thermal curing of the core resin composition. The heat curing accelerator does not include components corresponding to the thermosetting resin and cyclic carbonate compound described above. One type of heat curing accelerator may be used alone, or two or more types may be used in combination.

[0054] Examples of the thermal curing accelerator include phosphorus-based thermal curing accelerators, urea-based thermal curing accelerators, guanidine-based thermal curing accelerators, imidazole-based thermal curing accelerators, metal-based thermal curing accelerators, and amine-based thermal curing accelerators. A thermal radical generator may also be used as the thermal curing accelerator.

[0055] Examples of phosphorus-based curing accelerators include triphenylphosphine, tricyclohexylphosphine, tributylphosphine, methyldiphenylphosphine, phosphonium borate compounds, tetraphenylphosphonium tetraphenylborate, a salt of tetra-n-butylphosphonium and N-acetylglycine, n-butylphosphonium tetraphenylborate, tetrabutylphosphonium decanoate, (4-methylphenyl)triphenylphosphonium thiocyanate, tetraphenylphosphonium thiocyanate, and butyltriphenylphosphonium thiocyanate. Commercially available phosphorus-based curing accelerators may be used, such as "TBP-DA" manufactured by Hokko Chemical Industry Co., Ltd. and "AiL-01" manufactured by Ajinomoto Fine-Techno Co., Ltd. One type of phosphorus-based curing accelerator may be used alone, or two or more types may be used in combination.

[0056] Examples of the urea-based heat 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. Examples of the urea-based curing accelerator include aromatic dimethylureas such as toluene bis(dimethylurea), ...

[0057] 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. The guanidine curing accelerators may be used alone or in combination of two or more.

[0058] 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-undecylimidazolium 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 imidazole compounds such as 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. As the imidazole-based curing accelerator, commercially available products may be used, for example, "1B2PZ", "2E4MZ", "2MZA-PW", "2MZ-OK", "2MA-OK", "2MA-OK-PW", "2P4MZ", "2PHZ", "2PHZ-PW", "2P4MHZ-PW", "Cl1Z", "Cl1Z-CN", "Cl1Z-CNS", and "C11Z-A" manufactured by Shikoku Chemicals Corporation; "P200-H50" manufactured by Mitsubishi Chemical Corporation; and the like. The imidazole-based curing accelerator may be used alone or in combination of two or more.

[0059] 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. Metal-based curing accelerators may be used alone or in combination of two or more.

[0060] Examples of the amine curing accelerator include trialkylamines such as triethylamine and tributylamine, 4-dimethylaminopyridine, benzyldimethylamine, 2,4,6-tris(dimethylaminomethyl)phenol, and 1,8-diazabicyclo(5,4,0)-undecene. Commercially available amine curing accelerators may be used, such as "DMAP" manufactured by Tokyo Chemical Industry Co., Ltd. One type of amine curing accelerator may be used alone, or two or more types may be used in combination.

[0061] Examples of thermal radical generators include dialkyl peroxides such as di-t-butyl peroxide, dicumyl peroxide, and t-hexylperoxy-2-ethylhexanoate; diacyl peroxides such as lauroyl peroxide, benzoyl peroxide, benzoyltoluyl peroxide, and toluyl peroxide; peresters such as t-butyl peracetate, t-butyl peroxyoctoate, and t-butyl peroxybenzoate; ketone peroxides; peroxycarbonates; peroxyketals such as 1,1-di(t-amylperoxy)cyclohexane; azonitrile compounds such as 2,2'-azobis{2-methyl-N-[1,1-bis(hydroxymethyl)-2-hydroxyethyl]propionamide}; azoamide compounds such as 2,2'-azobis(2-amidinopropane) dihydrochloride and 2,2'-azobis[2-(2-imidazolin-2-yl)propane] dihydrochloride; azoalkane compounds such as 2,2'-azobis(2,4,4-trimethylpentane) and 4,4'-azobis(4-cyanopentanoic acid); azo compounds having an oxime skeleton such as 2,2'-azobis(2-methylpropionamideoxime); and azo compounds such as dimethyl 2,2'-azobis(isobutyrate). The thermal radical generators may be used alone or in combination of two or more.

[0062] The core resin composition may contain a thermoplastic resin as an optional component. The thermoplastic resin does not include components corresponding to the above-mentioned thermosetting resin, cyclic carbonate compound, and heat curing accelerator. The thermoplastic resin may be used alone or in combination of two or more.

[0063] The thermoplastic resin may be a resin that exhibits plasticity when heated, such as a phenoxy resin, a polyimide resin, a polyvinyl acetal resin, a polyolefin resin, a polybutadiene resin, a polyamide-imide resin, a polyetherimide resin, a polysulfone resin, a polyethersulfone resin, a polyphenylene ether resin, a polycarbonate resin, a polyether ether ketone resin, or a polyester resin.

[0064] Examples of the phenoxy resin include phenoxy resins having one or more skeletons selected from the group consisting of bisphenol A, bisphenol F, bisphenol S, bisphenolacetophenone, novolac, biphenyl, fluorene, dicyclopentadiene, norbornene, naphthalene, anthracene, adamantane, terpene, and trimethylcyclohexane. The terminal of the phenoxy resin may be any functional group such as a phenolic hydroxyl group or an epoxy group.

[0065] Specific examples of phenoxy resins include "1256" and "4250" manufactured by Mitsubishi Chemical Corporation (both phenoxy resins containing a bisphenol A skeleton); "YX8100" (phenoxy resin containing a bisphenol S skeleton) manufactured by Mitsubishi Chemical Corporation; "YX6954" (phenoxy resin containing a bisphenol acetophenone skeleton) manufactured by Mitsubishi Chemical Corporation; "FX280" and "FX293" manufactured by Nippon Steel Chemical & Material Co., Ltd.; "YX7200B35," "YL7500BH30," "YX6954BH30," "YX7553BH30," "YL7769BH30," "YL6794," "YL7213," "YL7290," and "YL7482" manufactured by Mitsubishi Chemical Corporation. One type of phenoxy resin may be used alone, or two or more types may be used in combination.

[0066] Specific examples of polyimide resins include "SLK-6100" manufactured by Shin-Etsu Chemical Co., Ltd., and "Rikacoat SN20" and "Rikacoat PN20" manufactured by New Japan Chemical Co., Ltd. One type of polyimide resin may be used alone, or two or more types may be used in combination.

[0067] Examples of polyvinyl acetal resins include polyvinyl formal resins and polyvinyl butyral resins, with polyvinyl butyral resins being preferred. Specific examples of polyvinyl acetal resins include the S-LEC BH series, BX series (e.g., BX-5Z), KS series (e.g., KS-1), BL series, and BM series, all manufactured by Sekisui Chemical Co., Ltd. One type of polyvinyl acetal resin may be used alone, or two or more types may be used in combination.

[0068] Examples of polyolefin resins include ethylene copolymer resins such as low-density polyethylene, very low-density polyethylene, high-density polyethylene, ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer, and ethylene-methyl acrylate copolymer; polyolefin polymers such as polypropylene and ethylene-propylene block copolymer; and the like. One type of polyolefin resin may be used alone, or two or more types may be used in combination.

[0069] Examples of polybutadiene resins include hydrogenated polybutadiene skeleton-containing resins, hydroxy group-containing polybutadiene resins, phenolic hydroxy group-containing polybutadiene resins, carboxy group-containing polybutadiene resins, acid anhydride group-containing polybutadiene resins, epoxy group-containing polybutadiene resins, isocyanate group-containing polybutadiene resins, urethane group-containing polybutadiene resins, polyphenylene ether-polybutadiene resins, etc. One type of polybutadiene resin may be used alone, or two or more types may be used in combination.

[0070] Specific examples of polyamide-imide resins include "Vylomax HR11NN" and "Vylomax HR16NN" manufactured by Toyobo Co., Ltd. Specific examples of polyamide-imide resins also include modified polyamide-imides such as "KS9100" and "KS9300" (polysiloxane skeleton-containing polyamide-imide) manufactured by Hitachi Chemical Co., Ltd. One type of polyamide-imide resin may be used alone, or two or more types may be used in combination.

[0071] A specific example of the polyethersulfone resin is "PES5003P" manufactured by Sumitomo Chemical Co., Ltd. One type of polyethersulfone resin may be used alone, or two or more types may be used in combination.

[0072] Specific examples of polysulfone resins include polysulfone "P1700" and "P3500" manufactured by Solvay Advanced Polymers, Inc. One type of polysulfone resin may be used alone, or two or more types may be used in combination.

[0073] A specific example of the polyphenylene ether resin is "NORYL SA90" manufactured by SABIC. One type of polyphenylene ether resin may be used alone, or two or more types may be used in combination. A specific example of the polyetherimide resin is "Ultem" manufactured by GE. One type of polyetherimide resin may be used alone, or two or more types may be used in combination.

[0074] The core resin composition may further contain other additives in addition to the above-mentioned components. Examples of the other additives include inorganic fillers, organic fillers, surface treatment agents, organometallic compounds, colorants, polymerization inhibitors, leveling agents, thickeners, antifoaming agents, UV absorbers, adhesion improvers, adhesion promoters, antioxidants, fluorescent brighteners, surfactants, flame retardants, dispersants, stabilizers, photopolymerization initiators, photopolymerization initiation aids, and photosensitizers. One type of the other additives may be used alone, or two or more types may be used in combination.

[0075] The core resin composition may contain a solvent as a volatile component. Examples of the solvent include ketones such as methyl ethyl ketone (MEK) and cyclohexanone; aromatic hydrocarbons such as xylene and tetramethylbenzene; glycol ethers such as methyl cellosolve, butyl cellosolve, methyl carbitol, butyl carbitol, propylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol diethyl ether, and triethylene glycol monoethyl ether; esters such as ethyl acetate, butyl acetate, butyl cellosolve acetate, carbitol acetate, and ethyl diglycol acetate; aliphatic hydrocarbons such as octane and decane; petroleum-based solvents such as petroleum ether, petroleum naphtha, hydrogenated petroleum naphtha, and solvent naphtha; and ether ester solvents such as propylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, ethyl diglycol acetate, γ-butyrolactone, and methyl methoxypropionate. The solvent may be used alone or in combination of two or more.

[0076] The core resin composition may be produced, for example, by a production method including mixing the above-mentioned components. The above-mentioned components may be mixed partially or entirely at the same time, or may be mixed sequentially. During the process of mixing the components, the temperature may be appropriately adjusted, and thus heating and / or cooling may be performed temporarily or throughout. Furthermore, stirring or shaking may be performed during the process of mixing the components. Furthermore, degassing may be performed under low-pressure conditions, such as under vacuum.

[0077] <Cladding Resin Composition> In the method for producing an optical waveguide of the present invention, the cladding resin composition contains a thermosetting resin and / or a photocurable resin. In particular, the cladding resin composition preferably contains a thermosetting resin.

[0078] The thermosetting resin that can be contained in the cladding resin composition is the same as the thermosetting resin that is contained in the core resin composition, including the preferred range. Therefore, when the cladding resin composition contains a thermosetting resin, the cladding resin composition preferably contains one or more resins selected from the group consisting of epoxy resins, (meth)acrylic resins, phenolic resins, and silicone resins.

[0079] When the cladding resin composition contains a thermosetting resin, the cladding resin composition may contain a cyclic carbonate compound as an optional component. The cyclic carbonate compound that the cladding resin composition may contain is the same as the cyclic carbonate compound that the core resin composition may contain.

[0080] When the cladding resin composition contains a thermosetting resin, the cladding resin composition may contain a heat-curing accelerator as an optional component. The heat-curing accelerator that the cladding resin composition may contain is the same as the heat-curing accelerator that the core resin composition may contain.

[0081] When the clad resin composition contains a thermosetting resin, the clad resin composition may contain a thermoplastic resin as an optional component. The thermoplastic resin that can be contained in the clad resin composition is the same as the thermoplastic resin that can be contained in the core resin composition.

[0082] The photocurable resin that can be contained in the cladding resin composition can be a resin that can be cured when exposed to light. Examples of the photocurable resin include radical polymerizable resins. Examples of the photocurable resin include resins that can be developed with a developer. One type of photocurable resin may be used alone, or two or more types may be used in combination.

[0083] The resin having a radical polymerizable group as the photocurable resin may be the component described in the section on thermosetting resins. From the viewpoint of enabling development with an alkaline developer, the resin having a radical polymerizable group as the photocurable resin is preferably a resin having an ethylenically unsaturated bond and a carboxyl group.

[0084] The resin having an ethylenically unsaturated bond and a carboxyl group may have a combination of a radically polymerizable group containing an ethylenically unsaturated bond and a carboxyl group. Examples of the radically polymerizable group include the groups described in the section on resins having radically polymerizable groups as thermosetting resins. Among these, a (meth)acryloyl group is preferred as the radically polymerizable group. The number of radically polymerizable groups per molecule of the resin may be one or two or more. When the resin contains two or more radically polymerizable groups per molecule, the radically polymerizable groups may be the same or different. Furthermore, the number of carboxyl groups per molecule of the resin may be one or two or more.

[0085] As the photocurable resin, a resin developable with a developer may be any of the conventionally known resins used when forming a solder resist layer on a printed wiring board. Among these, examples of resins developable with a developer include alkali-soluble resins having a phenolic hydroxyl group in the molecule, polybenzoxazole precursor resins, polyimide precursors, p-hydroxystyrene / styrene copolymers, (meth)acrylic resins, and the like. Of these, the resin developable with a developer preferably contains one or more selected from alkali-soluble resins having a phenolic hydroxyl group in the molecule, polyimide precursors, polybenzoxazole precursor resins, and acrylic resins. The resin developable with a developer may be used alone or in combination of two or more.

[0086] Examples of alkali-soluble resins having a phenolic hydroxyl group in the molecule include "TR4020G" manufactured by Asahi Organic Chemicals Co., Ltd.; AV Light series such as "TR4050G", "TR4080G", "TR5020G", "TR5050G", "TR6020G", "TR6050G", and "TR6080G" manufactured by Asahi Organic Chemicals Co., Ltd.; photoresist resin series manufactured by Sumitomo Bakelite Co., Ltd.; Resitop series manufactured by Gun-ei Chemical Industry Co., Ltd.; and "PR-30-40P", "PR-100L", "PR-100H", "PR-50", "PR-55", and "PR-56" manufactured by DIC Corporation. -1," "PR-56-2," "WR-101," "WR-102," "WR-103," "WR-104," and other Phenolite series; Lignite Corporation's "LF-100," "LF-110," "LF-120," "LF-200," "LF-400," and "LF-500"; Meiwa Kasei Co., Ltd.'s photoresist base resin series; Meiwa Kasei Co., Ltd.'s "MEHC-7851SS," "MEHC-78004S," "MEHC-7851-SS," "MEHC-7851-S," "MEHC-7851-M," "MEHC-7851-H," and "MEHC-7851-M" EHC-7800-4S” “MEHC-7800-SS” “MEHC-7800-S” “MEHC-7800-M” “MEH C-7800-H”, Nippon Kayaku Co., Ltd. “GPH-65”, “GPH-103”, “MEHC-7841-4S”; Honshu Kagaku Co., Ltd. “BisE” ", "BisP-TMC"; manufactured by Mitsui Chemicals Fine Co., Ltd. "BisA", "BisF", "BisP-M", "BisP-AP", "BisP-TMC"; sP-MIBK", "BisP-B", "Bis-Z", "BisP-CP", "o,o'-BPF", "BisP-IOTD", " BisP-IBTD”, “BisP-DED”, “BisP-BA”, “Bis-C”, “Bis26X-A”, “BisOPP- A", "BisOTBP-A", "BisOCHP-A", "BisOFP-A", "BisOC-Z", "BisOC-FL", " BisOC-CP”, “BisOCHP-Z”, “MethylenebisP-CR”, “TM-BPF”, “BisOC-F”, “Bis3M 6B-IBTD,” “BisOC-IST,” “BisP-IST,” “BisP-PRM,” and “BisP-LV.”The alkali-soluble resin having a phenolic hydroxyl group in the molecule may be used alone or in combination of two or more kinds.

[0087] Examples of polybenzoxazole precursor resins, polyimide precursors, p-hydroxystyrene / styrene copolymers, and (meth)acrylic resins include components described in JP 2018-169547 A, JP 2018-169627 A, WO 2010 / 134207 A, WO 2014 / 069202 A, JP 2020-101813 A, WO 2018 / 232214 A, etc. The polybenzoxazole precursor resins, polyimide precursors, p-hydroxystyrene / styrene copolymers, and (meth)acrylic resins may each be used alone or in combination of two or more.

[0088] When the cladding resin composition contains a photocurable resin that can be developed with a developer, the cladding resin composition may contain a crosslinking agent as an optional component. The crosslinking agent may be a component that can be made insoluble in the developing solution by a crosslinking reaction, or a component that can be cured by a crosslinking reaction to form a cladding layer. One type of crosslinking agent may be used alone, or two or more types may be used in combination.

[0089] As the crosslinking agent, for example, a compound having one or more, preferably two or more, alkoxymethyl groups in the molecule can be used. Examples of such resins include amino resins containing two or more alkoxymethyl groups in the molecule, and phenolic resins containing two or more alkoxymethyl groups in the molecule. Among them, amino resins containing two or more alkoxymethyl groups in the molecule are preferred because they have better photosensitivity. Examples of amino resins containing two or more alkoxymethyl groups in the molecule include melamine resins and urea resins, with melamine resins being preferred.

[0090] Specific examples of melamine resins include "MW-390," "MW-100LM," "MW-30HM," and "MX-750LM" manufactured by Sanwa Chemical Co., Ltd.; and the Cymel series manufactured by Allnex Japan Co., Ltd. Specific examples of urea resins include "MX-270," "MX-279," and "MX-280" manufactured by Sanwa Chemical Co., Ltd.; and the Cymel series manufactured by Allnex Japan Co., Ltd. One type of melamine resin may be used alone, or two or more types may be used in combination.

[0091] When the cladding resin composition contains a photocurable resin, the cladding resin composition may contain a photopolymerization initiator as an optional component. Photopolymerization initiators do not include components corresponding to the above-mentioned thermosetting resins, cyclic carbonate compounds, heat curing accelerators, thermoplastic resins, photocurable resins, and crosslinking agents. As the photopolymerization initiator, a compound capable of generating radicals or acids upon exposure to actinic rays can be used. One type of photopolymerization initiator may be used alone, or two or more types may be used in combination.

[0092] Examples of the photopolymerization initiator include oxime ester-based photopolymerization initiators, aminoketone-based photopolymerization initiators, acylphosphine-based photopolymerization initiators, α-hydroxyketone-based photopolymerization initiators, benzoin-based photopolymerization initiators, benzyl ketal-based photopolymerization initiators, etc. Furthermore, a photoacid generator may also be used as the photopolymerization initiator.

[0093] Examples of oxime ester photopolymerization initiators include 2-(benzoyloxyimino)-1-[4-(phenylthio)phenyl]octan-1-one (OXE01), [1-[9-ethyl-6-(2-methylbenzoyl)carbazol-3-yl]ethylideneamino]acetate (OXE02), ethanone, 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazol-3-yl]-, 1-(O-acetyloxime), etc. One type of oxime ester photopolymerization initiator may be used alone, or two or more types may be used in combination.

[0094] Examples of the aminoketone photopolymerization initiator include α-aminoketone photopolymerization initiators such as 2-methyl-1-phenyl-2-morpholinopropan-1-one, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one, 2-methyl-1-(4-hexylphenyl)-2-morpholinopropan-1-one, 2-ethyl-2-(dimethylamino)-1-(4-morpholinophenyl)butan-1-one, 2-benzyl-2-(dimethylamino)-1-(4-morpholinophenyl)butan-1-one, 2-(dimethylamino)-2-(4-methylphenylmethyl)-1-(4-morpholinophenyl)butan-1-one, and 2-methyl-1-(9,9-dibutylfluoren-2-yl)-2-morpholinopropan-1-one. The aminoketone-based photopolymerization initiators may be used alone or in combination of two or more.

[0095] Examples of the acylphosphine photopolymerization initiator include bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, (2,4,6-trimethylbenzoyl)diphenylphosphine oxide, polyoxyethylene glycerin ether tris[phenyl(2,4,6-trimethylbenzoyl)phosphinate] (Polymeric TPO-L), etc. One type of acylphosphine photopolymerization initiator may be used alone, or two or more types may be used in combination.

[0096] Examples of the α-hydroxyketone photopolymerization initiator include 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2-methyl-1-phenylpropanone, 1-[4-(2-hydroxyethoxy)phenyl]-2-hydroxy-2-methylpropanone, 2-hydroxy-1-{4-[4-(2-hydroxy-2-methylpropionyl)benzyl]phenyl}-2-methylpropan-1-one, etc. One type of α-hydroxyketone photopolymerization initiator may be used alone, or two or more types may be used in combination.

[0097] Examples of the benzoin-based photopolymerization initiator include benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether, etc. The benzoin-based photopolymerization initiator may be used alone or in combination of two or more.

[0098] Examples of the benzyl ketal photopolymerization initiator include 2,2-dimethoxy-2-phenylacetophenone, etc. The benzyl ketal photopolymerization initiator may be used alone or in combination of two or more.

[0099] The photopolymerization initiator may be a commercially available product. Specific examples of commercially available photopolymerization initiators include "Omnirad 907", "Omnirad 369", "Omnirad 379", "Omnirad 379EG", "Omnirad 819", and "Omnirad TPO" manufactured by IGM; "Irgacure TPO", "Irgacure OXE-01", and "Irgacure OXE-02" manufactured by BASF; and "N-1919" manufactured by ADEKA Corporation.

[0100] The photoacid generator used as the photopolymerization initiator may be a compound capable of generating an acid upon irradiation with actinic rays. Examples of the photoacid generator include halogen-containing compounds, diazoketone compounds, sulfone compounds, diazomethane compounds, and diazoquinone compounds. One type of photoacid generator may be used alone, or two or more types may be used in combination.

[0101] Examples of halogen-containing compounds that can be used as a photoacid generator include haloalkyl group-containing hydrocarbon compounds, haloalkyl group-containing heterocyclic compounds, etc. Specific preferred examples of the halogen-containing compound include 2-[2-(furan-2-yl)ethenyl]-4,6-bis(trichloromethyl)-s-triazine, 2-[2-(5-methylfuran-2-yl)ethenyl]-4,6-bis(trichloromethyl)-s-triazine, 2-(methoxyphenyl)-4,6-bis(trichloromethyl)-s-triazine, 2-[2-(4-methoxyphenyl)ethenyl]-4,6-bis(trichloromethyl)-s-triazine, 2-[2-(3,4-dimethoxyphenyl)ethenyl]-4,6-bis(trichloromethyl)-s-triazine, Examples of suitable halogen-containing compounds include s-triazine derivatives such as phenyl-bis(trichloromethyl)-s-triazine, 4-methoxyphenyl-bis(trichloromethyl)-s-triazine, styryl-bis(trichloromethyl)-s-triazine, and naphthyl-bis(trichloromethyl)-s-triazine. Specific examples of halogen-containing compounds include "TFE-triazine," "TME-triazine," "MP-triazine," "MOP-triazine," and "dimethoxytriazine" (photoacid generators based on halogen-containing compounds having a triazine skeleton), all manufactured by Sanwa Chemical Co., Ltd. One halogen-containing compound may be used alone, or two or more halogen-containing compounds may be used in combination.

[0102] Examples of diazoketone compounds, sulfone compounds, and diazoquinone compounds include the components described in JP 2018-169627 A, WO 2010 / 134207 A, WO 2014 / 069202 A, JP 2020-101813 A, and WO 2018 / 232214 A. As the photoacid generator, one type of diazoketone compound, sulfone compound, and diazoquinone compound may be used alone, or two or more types may be used in combination.

[0103] When the cladding resin composition contains a photocurable resin, the cladding resin composition may contain an epoxy resin as an optional component. The optional epoxy resin may be any of the components described in the section on thermosetting resins.

[0104] When the cladding resin composition contains a photocurable resin, the cladding resin composition may contain a photosensitizer as an optional component. Photosensitizers do not include components corresponding to the above-mentioned thermosetting resins, cyclic carbonate compounds, heat curing accelerators, thermoplastic resins, photocurable resins, crosslinking agents, and photopolymerization initiators. The use of a photosensitizer makes it possible to improve the photosensitivity of the photocurable resin. One type of photosensitizer may be used alone, or two or more types may be used in combination.

[0105] Examples of the photosensitizer include benzophenones such as Michler's ketone, 4,4'-bis(diethylamino)benzophenone, and 4-morpholinobenzophenone; cyclic alkanes such as 2,5-bis(4'-diethylaminobenzal)cyclopentane, 2,6-bis(4'-diethylaminobenzal)cyclohexanone, and 2,6-bis(4'-diethylaminobenzal)-4-methylcyclohexanone; chalcones such as 4,4'-bis(dimethylamino)chalcone and 4,4'-bis(diethylamino)chalcone; p-dimethylaminobenzal; indanones such as p-dimethylaminocinnamylidene indanone and p-dimethylaminobenzylidene indanone; thiazoles such as 2-(p-dimethylaminophenylbiphenylene)benzothiazole, 2-(p-dimethylaminophenylvinylene)benzothiazole and 2-(p-dimethylaminophenylvinylene)isonaphthothiazole; acetones such as 1,3-bis(4'-dimethylaminobenzal)acetone and 1,3-bis(4'-diethylaminobenzal)acetone; coumarins such as coumarins (7-aminocoumarin), 3-acetyl-7-dimethylaminocoumarin, 3-ethoxycarbonyl-7-dimethylaminocoumarin, 3-benzyloxycarbonyl-7-dimethylaminocoumarin, 3-methoxycarbonyl-7-diethylaminocoumarin, and 3-ethoxycarbonyl-7-diethylaminocoumarin; N-phenyl-N'-ethylethanolamine, N-phenyldiethanolamine, N-p-tolyldiethanolamine, N-phenylethanolamine, dimethylaminobenzoic acid isoamyl, diethyl amines such as isoamyl aminobenzoate; heterocyclic compounds such as 2-mercaptobenzimidazole, 2-mercaptobenzothiazole, 2-(p-dimethylaminostyryl)benzoxazole, 2-(p-dimethylaminostyryl)benzthiazole, 2-(p-dimethylaminostyryl)naphtho(1,2-d)thiazole, 1-phenyl-5-mercaptotetrazole, and 1-p-hydroxyphenyl-5-mercaptotetrazole; and styrenes such as 2-(p-dimethylaminobenzoyl)styrene.

[0106] The cladding resin composition may further contain other additives in addition to the above-mentioned components. Examples of the other additives include a thermal acid generator, an inorganic filler, an organic filler, a surface treatment agent, an organometallic compound, a colorant, a polymerization inhibitor, a leveling agent, a thickener, an antifoaming agent, an ultraviolet absorber, an adhesion improver, an adhesion imparting agent, an antioxidant, a fluorescent brightener, a surfactant, a flame retardant, a dispersant, a stabilizer, and a photopolymerization initiation aid. One type of the other additives may be used alone, or two or more types may be used in combination.

[0107] The clad resin composition may contain a solvent as a volatile component. The solvent that the clad resin composition may contain is the same as the solvent that the core resin composition may contain.

[0108] The cladding resin composition may be produced, for example, by a production method including mixing the above-mentioned components. The above-mentioned components may be mixed partially or entirely at the same time, or may be mixed sequentially. The temperature may be appropriately adjusted during the process of mixing the components, and thus heating and / or cooling may be performed temporarily or throughout. Furthermore, stirring or shaking may be performed during the process of mixing the components. Furthermore, degassing may be performed under low-pressure conditions, such as under vacuum.

[0109] [Resin Sheet] A resin sheet for producing an optical waveguide can be produced using the core resin composition and the clad resin composition described above. Specifically, a core resin sheet can be produced using the core resin composition, and a clad resin sheet can be produced using the clad resin composition. The resin sheet enables the production of an optical waveguide by a lamination method, making the production of an optical waveguide easier.

[0110] In one embodiment, the resin sheet includes a core resin sheet including a support and a resin composition layer including a core resin composition provided on the support, and a clad resin sheet including a support and a resin composition layer including a clad resin composition provided on the support.

[0111] The thickness of the resin composition layer is preferably 100 μm or less, more preferably 80 μm or less, and even more preferably 50 μm or less, regardless of whether it is a core resin sheet or a clad resin sheet. The lower limit of the thickness of the resin composition layer is not particularly limited, but may be, for example, 5 μm or more.

[0112] Examples of the support include films made of plastic materials, metal foils, and release papers, and one or more supports selected from the group consisting of films made of plastic materials and metal foils are preferred.

[0113] When a film made of a plastic material is used as the support, examples of the thermoplastic resin include polyesters such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), acrylics such as polycarbonate (PC) and polymethyl methacrylate (PMMA), cyclic polyolefins, triacetyl cellulose (TAC), polyether sulfide (PES), polyether ketone, polyimide, etc. Among these, one or more thermoplastic resins selected from the group consisting of polyethylene terephthalate and polyethylene naphthalate are preferred, and inexpensive polyethylene terephthalate is more preferred.

[0114] When a metal foil is used as the support, examples of the metal foil include copper foil and aluminum foil, with copper foil being preferred. The copper foil may be a foil made of a single metal, such as copper, or a foil made of an alloy of copper and another metal (e.g., tin, chromium, silver, magnesium, nickel, zirconium, silicon, titanium, etc.).

[0115] The support may be subjected to a matte treatment, a corona treatment, or an antistatic treatment on the surface that is bonded to the resin composition layer. Alternatively, a support with a release layer, which has a release layer on the surface that is bonded to the resin composition layer, may be used as the support. Examples of the release agent used in the release layer of the support with a release layer include one or more release agents selected from the group consisting of alkyd resins, polyolefin resins, urethane resins, and silicone resins. Examples of commercially available release agents include alkyd resin-based release agents such as "SK-1," "AL-5," and "AL-7" manufactured by Lintec Corporation, and "NSP-4" manufactured by Fujimori Kogyo Co., Ltd. In addition, examples of commercially available supports with release layers include PET films having a release layer containing an alkyd resin-based release agent as a main component, such as "SK-1," "AL-5," and "AL-7" manufactured by Lintec Corporation; "Lumirror T60" manufactured by Toray Industries, Inc.; "Purex" manufactured by Teijin Limited; "Unipeel" manufactured by Unitika Limited; and "NSH" manufactured by Fujimori Kogyo Co., Ltd.

[0116] The thickness of the support is not particularly limited, but is preferably in the range of 5 μm to 75 μm, and more preferably in the range of 10 μm to 60 μm. When a support with a release layer is used, it is preferable that the thickness of the entire support with a release layer is in the above range.

[0117] In one embodiment, the resin sheet may further include other layers as necessary. Examples of such other layers include a protective film conforming to the support and provided on the surface of the resin composition layer that is not bonded to the support (i.e., the surface opposite the support). The thickness of the protective film is not particularly limited, but is, for example, 1 μm to 40 μm. By laminating the protective film, it is possible to prevent adhesion of dust and scratches to the surface of the resin composition layer.

[0118] The resin sheet can be produced, for example, by preparing a resin varnish by dissolving a resin composition in a solvent, applying the resin varnish to a support using a die coater or the like, and then drying the varnish to form a resin composition layer. Examples of the solvent include the same organic solvents as those described as components that may be contained in the core resin composition. When producing the resin sheet, one organic solvent may be used alone, or two or more organic solvents may be used in combination.

[0119] Drying may be carried out by known methods such as heating or hot air blowing. Drying conditions are not particularly limited, but drying is carried out so that the solvent content in the resin composition layer becomes 10% by mass or less, preferably 5% by mass or less. Although this varies depending on the boiling point of the solvent in the resin varnish, for example, when a resin varnish containing 30% by mass to 60% by mass of solvent is used, the resin composition layer can be formed by drying at 50°C to 150°C for 3 to 10 minutes.

[0120] The resin sheet can be stored by being wound up in a roll. When the resin sheet has a protective film, the resin sheet can be used by peeling off the protective film.

[0121] [Optical Waveguide] The core resin composition and clad resin composition described above can be used to produce an optical waveguide. Hereinafter, an embodiment of the optical waveguide will be described with reference to the drawings.

[0122] According to the manufacturing method of the present invention, an optical waveguide 10 including a core layer 100 and a cladding layer 200 can be manufactured. The core layer 100 contains a cured product of a core resin composition, and preferably contains only the cured product of the core resin composition. The cladding layer 200 contains a cured product of a cladding resin composition, and preferably contains only the cured product of the cladding resin composition.

[0123] The core layer 100 is provided in the cladding layer 200. Thus, the core layer 100 is covered by the cladding layer 200. In one example, the entire peripheral surface of the core layer 100 is covered by the cladding layer 200. The core layer 100 and the cladding layer 200 are in direct contact with each other without any other layer therebetween, and therefore an interface 100I can be formed between the core layer 100 and the cladding layer 200. Because the core layer 100 has a higher refractive index than the cladding layer 200, 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.

[0124] Various wavelengths of light can be selected that can be transmitted by the optical waveguide 10. 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 light transmitted through the optical transmission line 10 is preferably 1300 nm to 1320 nm.

[0125] 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 with a wavelength of 1310 nm.

[0126] In order to realize a single-mode optical waveguide for light having a wavelength of 1310 nm in the optical waveguide 10, the refractive index of the cured product of the core resin composition is set to n ｃｏｒｅ The refractive index of the cured product of the cladding resin composition is n ｃｌａｄ If so, the difference between these (n ｃｏｒｅ -n ｃｌａｄ ) is preferably 0.1 or less. ｃｏｒｅ -n ｃｌａｄ The lower limit of ) is not particularly limited, and can be, for example, 0.001 or more.

[0127] 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 width L of the core layer 100 is preferably 0.5 μm or more, more preferably 1 μm or more, and even more preferably 2 μm or more, and is preferably 30 μm or less, more preferably 20 μm or less, and even more preferably 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.

[0128] It is desirable to set the spacing S of the core layers 100 appropriately within a range that allows light transmission. A specific range of the spacing S of the core layers 100 is preferably 50 μm or more, more preferably 70 μm or more, and even more preferably 100 μm or more, and is preferably 1000 μm or less, more preferably 700 μm or less, and even more preferably 500 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.

[0129] 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 even more preferably 2 μm or more, and is preferably 50 μm or less, more preferably 30 μm or less, and even more preferably 20 μm or less or 10 μm or less.

[0130] The thickness of the cladding layer 200 is greater than the thickness T 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 even more preferably 10 μm or more, and is preferably 100 μm or less, more preferably 60 μm or less, and even more preferably 40 μm or less or 30 μm or less.

[0131] The optical waveguide 10 may include any element other than the core layer 100 and the cladding layer 200, as needed. Examples of the optional element include a protective layer (not shown) that protects the core layer 100 and the cladding layer 200, and a conductive layer (not shown) such as a plating layer.

[0132] (i) forming a metal wiring pattern on a metal layer of a substrate (first substrate) with a metal layer; (ii) forming a first resin composition layer from a cladding resin composition so as to be in contact with the metal layer and the wiring pattern, and curing the first resin composition layer to form a first cladding layer; (iii) removing a substrate portion of the first substrate; (iv) removing the metal layer and the wiring pattern, and forming a recess corresponding to the wiring pattern; (v) forming a second resin composition layer from a core resin composition containing a thermosetting resin so as to be in contact with the recess, and curing the second resin composition layer to form a core underlayer; (vi) removing a portion of the core underlayer and forming a core layer; and (vii) forming a third resin composition layer from a cladding resin composition so as to be in contact with the core layer and the first cladding layer, and curing the third resin composition layer to form a second cladding layer.

[0133] As mentioned above, the present inventors investigated a technique for manufacturing an optical waveguide having a fine pattern using a thermosetting resin, in which a cladding is laser-processed to form a trench (groove) and a core is formed in the trench. However, they found that forming a trench in a cladding by laser processing can have problems, such as: 1) it is sometimes difficult to obtain a trench having the desired shape, such as a non-rectangular cross-sectional shape; 2) it is sometimes difficult to maintain a constant depth of the laser-processed trench, resulting in non-uniform trench depth in the direction of extension of the trench; and 3) the trench bottom can become rough. The present inventors found that, because the resulting core has a shape corresponding to the trench, the technique using the above-mentioned trench formation by laser processing makes it difficult to form a core having the desired cross-sectional shape and the desired thickness in the direction of extension. The present inventors also found that the technique using the above-mentioned trench formation by laser processing results in a core with a rough interface with the cladding. In contrast, the method of the present invention, in which a clad is formed to bury a fine wiring pattern formed on a substrate, the substrate is removed to expose the wiring pattern, and then the wiring pattern is removed to form a trench (recess) in the clad, can form a trench in the clad that has a desired cross-sectional shape and a desired thickness in the extension direction. Furthermore, the method of the present invention can achieve a trench with a smooth boundary surface with the clad. Therefore, the method of the present invention can uniformly form cores with fine line widths in the desired shape and pattern at predetermined intervals, thereby realizing an optical waveguide with excellent dimensional stability. Below, each step in the method of manufacturing an optical waveguide of the present invention will be described in detail.

[0134] 2 is a schematic cross-sectional view illustrating step (i) of the method for producing an optical waveguide of the present invention. As shown in FIG. 2, the method for producing an optical waveguide of the present invention includes the step of (i) forming a metal wiring pattern 310 on the metal layer 302 of a substrate (first substrate) 300 with a metal layer.

[0135] In the metal layer-attached substrate (first substrate) 300, there are no limitations on the material of the substrate portion 301 of the first substrate. Examples of the substrate portion 301 of the first substrate include a glass substrate, a single crystal silicon substrate, a metal substrate, a ceramic substrate, and a silicon substrate provided with an inorganic film such as a silicon oxide film. Among these, the substrate portion 301 of the first substrate is preferably a glass substrate, a single crystal silicon substrate, or a silicon substrate provided with an inorganic film, because these have excellent flatness.

[0136] In the glass substrate serving as the base material portion 301 of the first base material, examples of the glass material constituting the glass substrate include alkali-free glass, quartz glass, borosilicate glass, etc. One type of glass material may be used alone, or two or more types may be used in combination.

[0137] In the silicon substrate having an inorganic film as the substrate portion 301 of the first substrate, the inorganic film includes a silicon oxide film. When the substrate portion 301 of the first substrate is a silicon substrate having an inorganic film, the first substrate 300 includes an inorganic film including a silicon oxide film between the metal layer 302 and the silicon substrate.

[0138] The silicon substrate having an inorganic film as the substrate portion 301 of the first substrate may further include an inorganic film other than a silicon oxide film (hereinafter, sometimes referred to as an "optional inorganic film"). Examples of the optional inorganic film that the substrate may include include a silicon compound film (excluding a silicon oxide film) made of a silicon compound such as silicon nitride, silicon oxynitride, or silicon carbide; a ceramic film made of a ceramic material that constitutes the ceramic substrate described below; and a metal film made of a single metal or alloy. When the substrate portion 301 of the first substrate is a silicon substrate having an inorganic film and the inorganic film further includes an optional inorganic film, the layer structure of the silicon oxide film and the optional inorganic film in the inorganic film is not particularly limited. Therefore, when the substrate portion 301 of the first substrate is a silicon substrate having an inorganic film, the first substrate 300 may have a layer structure of metal layer 302 / silicon oxide film / optional inorganic film / silicon substrate, or a layer structure of metal layer 302 / optional inorganic film / silicon oxide film / silicon substrate.

[0139] In particular, it is preferable that the silicon substrate provided with an inorganic film as the substrate portion 301 of the first substrate contains only a silicon oxide film between the metal layer 302 and the silicon substrate.

[0140] In the ceramic substrate serving as the substrate portion 301 of the first substrate, examples of the ceramic material constituting the ceramic substrate include metal oxides, transition metal oxides, metal nitrides, and boride-based ceramics. Here, the metal oxides and transition metal oxides may include composite oxides. Specific examples of ceramic materials include metal oxides such as aluminum oxide (alumina), zinc oxide, magnesium oxide, and calcium oxide; composite oxides such as diamond, sapphire, cordierite, β-spondumene, forsterite, cermet, steatite, aluminum titanate, barium titanate, calcium titanate, strontium titanate, zinc titanate, mullite, spinel, calcium zirconate, strontium zirconate, barium zirconate titanate, bismuth titanate, and strontium bismuth titanate; nitrides, nitrides, and nitrides. Examples of the ceramic material include metal nitrides such as aluminum oxide, boron nitride, and titanium nitride; transition metal oxides such as zirconium oxide, yttrium oxide, nickel oxide, iron oxide, titanium oxide, tantalum oxide, tin oxide, vanadium oxide, cerium oxide, and chromium oxide; soft magnetic materials such as ferrites such as Mg—Zn ferrite, Mn—Zn ferrite, Mn—Mg ferrite, Cu—Zn ferrite, Mg—Mn—Sr ferrite, Ni—Zn ferrite, Ni—Cu—Zn ferrite, Ni—Cu—Zn—Mg ferrite, and Ba ferrite; boride-based ceramics; and the like. One type of ceramic material may be used alone, or two or more types may be used in combination.

[0141] In the substrate (first substrate) 300 with a metal layer, the metal layer 302 contains one or more metals selected from the group consisting of gold, platinum, palladium, silver, copper, aluminum, cobalt, chromium, zinc, nickel, titanium, tungsten, iron, tin, and indium. The metal layer 302 may be a single metal layer or an alloy layer. Examples of the alloy layer include a layer formed from an alloy of two or more metals selected from the above group (e.g., a nickel-chromium alloy, a copper-nickel alloy, and a copper-titanium alloy). Among these, from the viewpoints of versatility, cost, ease of patterning, etc., a single metal layer of chromium, nickel, titanium, aluminum, zinc, gold, palladium, silver, or copper, or an alloy layer of a nickel-chromium alloy, a copper-nickel alloy, or a copper-titanium alloy is preferred. A single metal layer of chromium, nickel, titanium, aluminum, zinc, gold, palladium, silver, or copper, or an alloy layer of a nickel-chromium alloy or a copper-titanium alloy is more preferred, and a single metal layer of copper or an alloy layer of a copper-titanium alloy is even more preferred.

[0142] The metal layer 302 may have a single layer structure or a multi-layer structure in which two or more single metal layers or alloy layers made of different types of metals or alloys are stacked.

[0143] The metal forming the wiring pattern 310 is the same as the metal that may be contained in the metal layer 302. In particular, the metal forming the wiring pattern 310 preferably contains copper. The metal forming the wiring pattern 310 may contain only copper, or may contain copper and any metal other than copper. For example, the wiring pattern 310 may include a layer of an alloy containing copper and any metal. Furthermore, for example, the wiring pattern 310 may include a layer containing copper and another layer containing any metal. Examples of the optional metal include gold, platinum, palladium, silver, aluminum, cobalt, chromium, zinc, nickel, titanium, tungsten, iron, tin, and indium. One type of the optional metal may be used alone, or two or more types may be used in combination.

[0144] The minimum line and space (L / S) of the wiring pattern 310 may be determined according to the desired width L and spacing S of the core layer 100 .

[0145] The thickness of the wiring pattern 310 may be determined according to the desired thickness T of the core layer 100. The thickness of the wiring pattern 310 is the same as the thickness T of the core layer 100 or is smaller than the thickness T of the core layer 100. In a preferred embodiment, the thickness of the wiring pattern 310 is the same as the thickness T of the core layer 100.

[0146] In step (i), the method for forming the metal wiring pattern 310 is not particularly limited. Among these, from the viewpoints of versatility of metal layer formation, cost, ease of patterning, and the like, plating is preferably used as the method for forming the wiring pattern 310. For example, the method for forming the wiring pattern 310 by plating includes, in this order, (i-1) a step of forming a mask layer on the metal layer of a substrate (first substrate) with a metal layer so as to expose the metal layer in accordance with the metal wiring pattern, (i-2) a step of forming a metal wiring pattern by electrolytic plating on the portion of the metal layer not covered by the mask layer, and (i-3) a step of removing the mask layer, thereby enabling the metal wiring pattern 310 to be formed.

[0147] FIG. 3 is a schematic cross-sectional view illustrating step (i-1) according to one embodiment of the method for manufacturing an optical waveguide of the present invention. In step (i-1), the mask layer 400 can be formed using, for example, a photoresist (not shown). Specifically, the mask layer 400 can be formed by forming a photoresist on the metal layer 302 of the metal-layer-attached substrate (first substrate) 300, and then performing exposure and development using a photomask (not shown) corresponding to the desired pattern shape. The photoresist may be a conventionally known photoresist that can be developed into the desired conductor circuit pattern, and either a film-type photoresist (dry film photoresist) or a liquid photoresist may be used. Examples of photoresist compositions include novolac resin compositions and acrylic resin compositions. Commercially available photoresists may be used, such as "RY-5115" manufactured by Resonac Corporation and "ALPHO 20A263" manufactured by Nikko Materials Co., Ltd.

[0148] 4 is a schematic cross-sectional view illustrating step (i-2) according to one embodiment of the method for manufacturing an optical waveguide of the present invention. As shown in FIG. 4, in step (i-2), after forming a mask layer 400, a metal wiring pattern 310 is formed on the metal layer 302 by electrolytic plating. Specifically, in step (i-2), the metal wiring pattern 310 is formed by electrolytic plating on the portion 302S of the metal layer 302 that is not covered by the mask layer 400.

[0149] In electrolytic plating, a metal wiring pattern 310 can be formed in an electrolytic plating solution, which is a solution containing metal ions. For example, a metal layer 302 and an electrode (not shown) are placed in the plating solution, and a direct current is applied between the metal layer 302 and the electrode from a power source. Metal ions are reduced in the portions 302S of the metal layer 302 that are not covered by the mask layer 400, causing the metal to deposit, thereby forming the metal wiring pattern 310.

[0150] Generally, an aqueous solution of a metal salt is used as the electroplating solution. There are no limitations on the metal salt as long as it allows the formation of an electroplated layer. When copper is used as the metal, examples of the copper salt include copper sulfate such as copper sulfate pentahydrate, copper halides such as copper chloride, copper acetate, copper nitrate, copper tetrafluoroborate, copper alkylsulfonate, copper arylsulfonate, copper sulfamate, copper perchlorate, and copper gluconate, with copper sulfate being preferred. The concentration of the metal salt in the electroplating solution may be, for example, 50 g / L or more and 400 g / L or less. It is more preferable that the concentration of the metal salt in the electroplating solution be a saturated concentration. The electroplating solution may also contain an acid such as sulfuric acid, methanesulfonic acid, ethanesulfonic acid, propanesulfonic acid, or hydrochloric acid; a halide ion supplier; a brightener; and additives such as a surfactant.

[0151] In step (i-3), after forming the metal wiring pattern 310, the mask layer 400 is removed. There are no limitations on the method for removing the mask layer 400. For example, the mask layer 400 formed of photoresist can be removed by contacting it with an appropriate stripping solution depending on the composition of the mask layer 400. In one example, the mask layer 400 can be removed using an alkaline stripping solution such as a sodium hydroxide solution.

[0152] The method for manufacturing an optical waveguide of the present invention may further include, as an optional step after step (i) and before step (ii), (ii') a step of planarizing the surface of the wiring pattern 310 by chemical mechanical polishing (CMP).

[0153] In chemical mechanical polishing (CMP), the surface of the wiring pattern 310 is planarized using an abrasive slurry.

[0154] Any conventionally known abrasive may be used as the abrasive (abrasive grains) contained as dispersoid in the polishing slurry, as long as it can planarize the wiring pattern 310. Examples of abrasive materials include inorganic particles such as silica, alumina, cerium oxide, titanium oxide, and chromium oxide; and organic particles such as diamond and hard resin particles. One type of abrasive may be used alone, or two or more types may be used in combination.

[0155] The smaller the average particle size of the abrasive, the easier it is to obtain a wiring pattern 310 with low surface roughness. The average particle size of the abrasive may be, for example, 1 μm or less, 0.5 μm or less, 0.4 μm or less, 0.2 μm or less, etc., and the lower limit of the average particle size is not particularly limited, but may be, for example, 0.005 μm or more, 0.01 μm or more, etc.

[0156] The concentration of the abrasive in the polishing slurry is not particularly limited, and may be determined, for example, in the range of 0.01% by mass to 30% by mass (preferably 0.1% by mass to 25% by mass).

[0157] In view of the dispersibility of abrasive, polishing slurry can also contain dispersant.As dispersant, any dispersant that is conventionally known and used in the polishing slurry of chemical mechanical polishing can be used.As such dispersant, various surfactants such as ionic surfactant, nonionic surfactant, etc.; acids such as hydrochloric acid and nitric acid; etc.Can be listed.In view of achieving good dispersibility of abrasive, the concentration of dispersant in polishing slurry can be suitably determined in relation to the concentration of abrasive.

[0158] The polishing slurry may further contain other components as long as they do not impair the effect of the present invention, and such other components may include, for example, pH adjuster, thickener, oxidizer, corrosion inhibitor, etc. The concentration of these other components in the polishing slurry may be appropriately determined according to the intended purpose.

[0159] Water may be used as the dispersion medium of the polishing slurry.

[0160] The polishing rate of the surface of the wiring pattern 310 can be adjusted by selecting and changing the hardness and average particle size of the abrasive, and the concentration of the abrasive in the polishing slurry. For example, the higher the hardness of the abrasive, the higher the polishing rate of the surface of the wiring pattern 310 tends to be. Also, for example, the larger the average particle size of the abrasive, the higher the polishing rate of the surface of the wiring pattern 310 tends to be. Also, for example, the higher the concentration of the abrasive in the polishing slurry, the higher the polishing rate of the surface of the wiring pattern 310 tends to be.

[0161] In chemical mechanical polishing (CMP), the pressure during polishing (pressure between the carrier holding the substrate and the polishing pad) may be appropriately determined to achieve a desired polishing rate, depending on the composition of the wiring pattern 310 (the type and amount of metal to be formed), etc. Furthermore, the rotation speed of the carrier holding the substrate and the rotation speed of the polishing platen holding the polishing pad may be appropriately determined to achieve a desired polishing rate, depending on the composition of the wiring pattern 310, etc. For example, the higher the pressure during polishing, the higher the polishing rate of the wiring pattern 310 tends to be. Furthermore, for example, the higher the rotation speed of the carrier and the polishing platen, the higher the polishing rate of the wiring pattern 310 tends to be.

[0162] The chemical mechanical polishing of the wiring pattern 310 may be performed using a commercially available chemical mechanical polishing apparatus, such as the polishing apparatus "LaboForce-100" manufactured by Struers.

[0163] 5 and 6 are schematic cross-sectional views illustrating step (ii) of the method for producing an optical waveguide of the present invention. As shown in Fig. 5 and 6, the method for producing an optical waveguide of the present invention includes the step of: (ii) forming a first resin composition layer 210 from a cladding resin composition so as to be in contact with the metal layer 302 and the wiring pattern 310, and curing the first resin composition layer 210 to form a first cladding layer 211.

[0164] There are no particular limitations on the method for forming the first resin composition layer 210. For example, the first resin composition layer 210 may be formed by applying a cladding resin composition onto the metal layer 302 and the wiring pattern 310. 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.

[0165] 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.

[0166] The cladding resin composition may be applied in one application or in multiple applications. The cladding resin composition may also be applied by a combination of different application methods. To avoid contamination, the cladding resin composition is preferably applied in an environment where foreign matter is unlikely to be generated, such as a clean room.

[0167] After application of the cladding resin composition, the first resin 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. It is preferable to set the drying conditions appropriately depending on the composition of the cladding resin composition. Specifically, the drying temperature is preferably 50°C or higher, more preferably 70°C or higher, and even more preferably 80°C or higher, and preferably 150°C or lower, more preferably 130°C or lower, and even more preferably 120°C or lower. The drying time is preferably 30 seconds or higher, more preferably 60 seconds or higher, and even more preferably 120 seconds or higher, and preferably 60 minutes or shorter, more preferably 20 minutes or shorter, and even more preferably 5 minutes or shorter.

[0168] The first resin composition layer 210 may be formed, for example, using the clad resin sheet described above. Specifically, the resin composition layer of the clad resin sheet may be laminated so as to contact the metal layer 302 and the wiring pattern 310, thereby forming the first resin composition layer 210 on the metal layer 302 and the wiring pattern 310. The clad resin sheet may be laminated on the metal layer 302 and the wiring pattern 310 by, for example, thermocompression bonding the clad resin sheet to the metal layer 302 and the wiring pattern 310 from the support side. Examples of a member (hereinafter also referred to as a "thermocompression bonding member") that thermocompresses the clad resin sheet to the metal layer 302 and the wiring pattern 310 include a heated metal plate (such as a stainless steel panel) or a metal roll (such as a stainless steel roll). The thermocompression bonding member may be pressed directly against the resin sheet, or may be pressed through an elastic material such as heat-resistant rubber so that the clad resin sheet can sufficiently conform to the irregularities formed by the metal layer 302 and the wiring pattern 310. Furthermore, before laminating the clad resin sheet, preheating may be performed as necessary to heat the resin sheet and the metal layer-equipped substrate (first substrate) 300 .

[0169] The lamination of the clad resin sheet may be carried out by a vacuum lamination method. In the vacuum lamination method, the thermocompression temperature is preferably in the range of 60°C to 160°C, more preferably 80°C to 140°C. The thermocompression pressure is preferably in the range of 0.098 MPa to 1.77 MPa, more preferably 0.29 MPa to 1.47 MPa. The thermocompression time is preferably in the range of 20 seconds to 400 seconds, more preferably 30 seconds to 300 seconds. The lamination of the clad resin sheet may be carried out under reduced pressure conditions, preferably a pressure of 26.7 hPa or less. Lamination by the vacuum lamination method may be carried out in a batch system or in a continuous system using a roll.

[0170] The lamination may be performed using a commercially available vacuum laminator, such as a vacuum pressure laminator manufactured by Meiki Seisakusho Co., Ltd., a vacuum applicator manufactured by Nikko Materials Co., Ltd., or a batch-type vacuum pressure laminator.

[0171] When the first resin composition layer 210 is formed using a clad resin sheet having a support, the support is peeled off at an appropriate time.

[0172] The first resin composition layer 210 formed on the metal layer 302 and the wiring pattern 310 in step (ii) contains a cladding resin composition, and preferably contains only a cladding resin composition.

[0173] The curing method of the first resin composition layer 210 may be determined appropriately depending on the composition of the cladding resin composition. For example, when the cladding resin composition contains a thermosetting resin, the first resin composition layer 210 may be cured by heat treatment to form the first cladding layer 211. For example, when the cladding resin composition contains a photocurable resin, the first resin composition layer 210 may be cured by exposure treatment to form the first cladding layer 211. For example, when the cladding resin composition contains a thermosetting resin and a photocurable resin, the first resin composition layer 210 may be cured by a combination of heat treatment and exposure treatment to form the first cladding layer 211.

[0174] The conditions for the heat treatment of the cladding resin composition may be selected depending on the type and amount of the thermosetting resin in the cladding resin composition. For example, the curing temperature is preferably 120°C to 240°C, more preferably 140°C to 220°C. The curing time is preferably 5 minutes to 120 minutes, more preferably 10 minutes to 100 minutes, and even more preferably 15 minutes to 100 minutes.

[0175] The heat treatment of the cladding resin composition may include preheating the first resin composition layer 210 at a temperature lower than the curing temperature. As an example, prior to thermally curing the first resin composition layer 210, the first resin composition layer 210 may be preheated for, for example, 5 minutes or more, preferably 5 minutes to 150 minutes, more preferably 15 minutes to 120 minutes, and even more preferably 15 minutes to 100 minutes at a temperature of, for example, 50°C to 150°C, preferably 60°C to 140°C, and more preferably 70°C to 130°C. Preheating may be performed, for example, after the formation of the first resin composition layer 210.

[0176] The conditions for the exposure treatment of the cladding resin composition may be selected depending on the type and amount of the photocurable resin in the cladding resin composition. For example, the exposure dose is preferably 10 mJ / cm ２ More preferably, 50 mJ / cm ２ More preferably, 200 mJ / cm ２ or more, preferably 10,000 mJ / cm ２ or less, more preferably 8,000 mJ / cm ２ More preferably, 4,000 mJ / cm or less ２ Below, 3,000mJ / cm ２ Below, 2,000mJ / cm ２ or less, or 1,000 mJ / cm ２ The following is the result.

[0177] When the first clad layer 211 is formed using a clad resin sheet having a support, in step (ii), a support (not shown) may be present on the first clad layer 211. When a support is present on the first clad layer 211, exposure may be performed through the support, or exposure may be performed after removing the support.

[0178] 6 , in step (ii), the first resin composition layer 210 is cured to form a first clad layer 211. This first clad layer 211 (i.e., the cured first resin composition layer 210) forms a part of the clad layer 200.

[0179] In the method for manufacturing an optical waveguide of the present invention, step (ii) preferably includes, before curing the first resin composition layer 210, (ii-1) joining a support (second substrate) (not shown) to the first resin composition layer 210 on the surface of the first resin composition layer 210 opposite to the substrate with the metal layer (first substrate). Such a support (second substrate) makes it possible to easily remove the substrate portion 301 of the first substrate in step (iii).

[0180] There are no limitations on the material of the support (second substrate), and examples thereof include a glass substrate, a single crystal silicon substrate, a metal substrate, a silicon substrate provided with an inorganic film, a ceramic substrate, etc. Among these, the support (second substrate) is preferably a glass substrate, a single crystal silicon substrate, or a silicon substrate provided with an inorganic film, because of its excellent flatness.

[0181] In the glass substrate as the second base material, examples of the glass material constituting the glass substrate include alkali-free glass, quartz glass, borosilicate glass, etc. One type of glass material may be used alone, or two or more types may be used in combination.

[0182] In the silicon substrate having an inorganic film as the second substrate, the inorganic film includes a silicon oxide film. When the second substrate is a silicon substrate having an inorganic film, the second substrate includes an inorganic film including a silicon oxide film on a surface to be bonded to the first resin composition layer 210.

[0183] The silicon substrate provided with an inorganic film as the second substrate may further include an optional inorganic film. The optional inorganic film that may be provided on the substrate is the same as the optional inorganic film that may be provided on the substrate portion 301 of the first substrate, as described above. When the second substrate is a silicon substrate provided with an inorganic film and the inorganic film further includes an optional inorganic film, the layer structure of the silicon oxide film and the optional inorganic film in the inorganic film is not particularly limited. Therefore, when the second substrate is a silicon substrate provided with an inorganic film, the second substrate may have a layer structure of silicon oxide film / optional inorganic film / silicon substrate, or may have a layer structure of optional inorganic film / silicon oxide film / silicon substrate.

[0184] In particular, it is preferable that the silicon substrate provided with the inorganic film as the second base material includes only a silicon oxide film on the surface that is bonded to the first resin composition layer 210 .

[0185] There are no particular limitations on the method for joining the support (second substrate) to the first resin composition layer 210. For example, step (ii-1) may be performed by laminating the support (second substrate) so that it is in contact with the surface of the first resin composition layer 210 opposite to the metal layer-formed substrate (first substrate). The lamination of the support (second substrate) can be performed in the same manner as the lamination of the clad resin sheet described above.

[0186] 7 is a schematic cross-sectional view illustrating step (iii) of the method for manufacturing an optical waveguide of the present invention. As shown in FIG. 7, the method for manufacturing an optical waveguide of the present invention includes the step of (iii) removing base material portion 301 of the first base material.

[0187] In step (iii), the method for removing substrate portion 301 of the first substrate is not particularly limited, and it is preferable to remove substrate portion 301 of the first substrate by peeling it off and / or polishing it. Therefore, step (iii) preferably includes (iii-1) a step of peeling off substrate portion 301 of the first substrate, and / or (iii-2) a step of polishing substrate portion 301 of the first substrate.

[0188] In step (iii-1), for example, the substrate portion 301 of the first substrate can be pulled relatively to the metal layer 302, thereby peeling off the substrate portion 301 of the first substrate.

[0189] In step (iii-2), the polishing conditions for the substrate portion 301 of the first substrate include chemical mechanical polishing using a chemical mechanical polishing (CMP) device; mechanical polishing methods such as belt polishing, buffing, ceramic polishing, grinding using a surface grinder, and surface grinding using a rotating grinding wheel. In this specification, the term "polishing" may also include grinding unless otherwise specified. Various grit sizes of abrasive grains may be used depending on the state of the target polished surface. Regarding the degree of polishing of the substrate portion 301 of the first substrate, polishing may be terminated, for example, when the surface of the metal layer 302 is exposed.

[0190] 8 is a schematic cross-sectional view illustrating step (iv) of the method for manufacturing an optical waveguide of the present invention. As shown in Fig. 8, the method for manufacturing an optical waveguide of the present invention includes the step of: (iv) removing the metal layer 302 and the wiring pattern 310, and forming a recess 500 corresponding to the wiring pattern 310.

[0191] In the step (iv), the method for removing the metal layer 302 and the wiring pattern 310 is not particularly limited. For example, the metal layer 302 and the wiring pattern 310 may be removed by a dry treatment using gas, plasma, various beams, or the like, or by a wet treatment using an etching solution. Among these, it is preferable to remove the metal layer 302 and the wiring pattern 310 by a wet treatment using an etching solution. Therefore, the step (iv) preferably includes the step (iv-1) of removing the metal layer 302 and the wiring pattern 310 by a wet treatment using an etching solution, and forming a recess 500 corresponding to the wiring pattern 310.

[0192] Examples of the etching solution include an etching solution containing hydrogen peroxide as a main component (hydrogen peroxide-based etching solution), an acidic etching solution, an alkaline etching solution, etc., and hydrogen peroxide-based etching solutions are preferred.

[0193] The hydrogen peroxide-based etching solution is preferably an etching solution containing hydrogen peroxide and an inorganic acid. Examples of inorganic acids include sulfuric acid, nitric acid, and phosphoric acid. Examples of commercially available hydrogen peroxide-based etching solutions include the SAC series of etching solutions manufactured by JCU Corporation. Examples of acidic etching solutions include aqueous solutions of ferric chloride, aqueous solutions containing sodium peroxodisulfate and sulfuric acid, and etching solutions mainly containing nitric acid and sulfuric acid. Examples of commercially available acidic etching solutions include "NH-1865" manufactured by MEC Corporation and "Melstrip N-950" manufactured by Meltex Corporation. Examples of commercially available alkaline etching solutions include "CF-6000" manufactured by MEC Corporation and "E-Process-WL" manufactured by Meltex Corporation.

[0194] In step (iv-1), the metal layer 302 and the wiring pattern 310 can be removed by, for example, a method of immersing the metal layer 302 and the wiring pattern 310 in an etching solution, or a method of spraying the etching solution onto the metal layer 302 and the wiring pattern 310. In one example, the temperature of the etching solution is preferably 5°C or higher, more preferably 10°C or higher, and even more preferably 15°C or higher, and is preferably 60°C or lower, more preferably 50°C or lower, and even more preferably 40°C or lower.

[0195] 9 and 10 are schematic cross-sectional views illustrating step (v) of the method for manufacturing an optical waveguide of the present invention. As shown in Figures 9 and 10, the method for manufacturing an optical waveguide of the present invention includes the step of (v) forming a second resin composition layer 110 from a core resin composition containing a thermosetting resin so as to be in contact with the recess 500, and curing the second resin composition layer 110 to form a core base layer 111. The second resin composition layer 110 is formed so as to be in contact with the recess 500 and to cover the surface of the first cladding layer 211 that was in contact with the metal layer 302.

[0196] The method for forming the second resin composition layer 110 is not particularly limited. For example, the second resin composition layer 110 may be formed by applying a core resin composition to the recess 500. From the viewpoint of smooth application, a varnish-like core resin composition containing a solvent may be prepared, and the varnish-like core resin composition may be applied. The core resin composition may be applied in the same manner as the cladding resin composition. After application of the core resin composition, the second resin composition layer 110 may be dried, if necessary. The second resin composition layer 110 may be dried using the same method and conditions as those for drying the first resin composition layer 210.

[0197] The second resin composition layer 110 may be formed, for example, using the core resin sheet described above. Specifically, the second resin composition layer 110 can be formed by laminating the resin composition layer of the core resin sheet so that it is in contact with the recess 500. The lamination of the core resin sheet may be performed using the same method and conditions as those for laminating the cladding resin sheet. When the second resin composition layer 110 is formed using a core resin sheet provided with a support, the support is peeled off at an appropriate time.

[0198] The second resin composition layer 110 formed in step (v) so as to be in contact with the entire first resin composition layer 210 contains a core resin composition, and preferably contains only the core resin composition.

[0199] Furthermore, the curing of the second resin composition layer 110 may be determined appropriately depending on the composition of the core resin composition. In the method for manufacturing an optical waveguide of the present invention, since the core resin composition contains a thermosetting resin, the second resin composition layer 110 is cured by heat treatment to form the core underlayer 111. Furthermore, if necessary, an exposure treatment may be performed to form the core underlayer 111. The conditions for the heat treatment (including the exposure treatment, if necessary) in forming the core underlayer 111 may be the same as the conditions for the heat treatment (and exposure treatment) of the cladding resin composition.

[0200] 10 , the second resin composition layer 110 is cured in step (v) to form a core underlayer 111. This core underlayer 111 (i.e., the cured second resin composition layer 110) includes the core layer 100.

[0201] 11 is a schematic cross-sectional view illustrating step (vi) of the method for manufacturing an optical waveguide of the present invention. As shown in FIG. 11, the method for manufacturing an optical waveguide of the present invention includes a step (vi) of removing a part of the core underlayer 111 to form a core layer 100.

[0202] In step (vi), the method for removing a portion of the core underlayer 111 is not particularly limited. Examples include laser irradiation, etching, mechanical drilling, and chemical mechanical polishing (CMP). Among these, from the viewpoint of easily controlling the thickness T of the core layer 100 and easily adjusting the flatness of the core layer, it is preferable to polish a portion of the core underlayer 111 by chemical mechanical polishing (CMP). Therefore, step (vi) preferably includes a step (vi-1) of polishing a portion of the core underlayer 111 by chemical mechanical polishing (CMP) to form the core layer 100. The polishing conditions for the core underlayer 111 may be the same as those for step (ii'), for example.

[0203] In step (vi), the degree of removal (preferably, chemical mechanical polishing) of the portion of the core underlayer 111 may be determined depending on the desired thickness T of the core layer 100. In a preferred embodiment, the thickness of the wiring pattern 310 is the same as the thickness T of the core layer 100, and the depth of the recess 500 is the same as the thickness of the wiring pattern 310. Therefore, when the surface of the first cladding layer 201 is exposed, the removal (preferably, chemical mechanical polishing) of the portion of the core underlayer 111 is terminated, thereby forming the core layer 100.

[0204] 12 and 13 are schematic cross-sectional views illustrating step (vii) of the method for manufacturing an optical waveguide of the present invention. As shown in FIGS. 12 and 13, the method for manufacturing an optical waveguide of the present invention includes the step of (vii) forming a third resin composition layer 220 from a cladding resin composition so as to be in contact with the core layer 100 and the first cladding layer 211, and curing the third resin composition layer 220 to form a second cladding layer 221. The third resin composition layer 220 is formed so as to cover the entire peripheral surface of the core layer 100 that is not in contact with the first cladding layer 211. Thus, the third resin composition layer 220 is formed so as to cover the core layer 100 and also to be in contact with the first cladding layer 211.

[0205] The method for forming the third resin composition layer 220 is not particularly limited. For example, the third resin composition layer 220 may be formed by applying a cladding photosensitive resin composition to the core layer 100 and the first cladding layer 211. The application of the cladding resin composition to form the third resin composition layer 220 may be carried out in the same manner as the application of the cladding resin composition to form the first resin composition layer 210. Furthermore, after application of the cladding resin composition, the third resin composition layer 220 may be dried, if necessary. The third resin composition layer 220 may be dried using the same method and conditions as those used to dry the first resin composition layer 210.

[0206] The third resin composition layer 220 may be formed using, for example, the above-mentioned clad resin sheet. Specifically, the third resin composition layer 220 can be formed by laminating the resin composition layer of the clad resin sheet so as to be in contact with the core layer 100 and the anterior first clad layer 211. The lamination of the clad resin sheet to form the third resin composition layer 220 may be performed using the same method and conditions as the lamination of the clad resin sheet to form the first resin composition layer 210. When the third resin composition layer 220 is formed using a clad resin sheet provided with a support, the support is peeled off at an appropriate time.

[0207] The third resin composition layer 220 formed in the step (vii) so as to be in contact with the core layer 100 and the first clad layer 211 contains a clad resin composition, and preferably contains only a clad resin composition.

[0208] The curing method of the third resin composition layer 220 may be determined appropriately depending on the composition of the cladding resin composition. For example, the curing method of the third resin composition layer 220 may be performed in the same manner as the curing method of the first resin composition layer 210.

[0209] 13 , by curing the third resin composition layer 220 in step (vii), the second clad layer 221 can be formed. This second clad layer 221 (i.e., the cured third resin composition layer 220) forms a part of the clad layer 200. The clad layer 200 is then formed from the first clad layer 211 and the second clad layer 221. Thus, an optical waveguide 10 can be obtained that includes the clad layer 200 including the first clad layer 211 and the second clad layer 221, and the core layer 100 provided in this clad layer 200.

[0210] When the method for producing an optical waveguide includes step (ii-1), the method for producing an optical waveguide of the present invention may further include, after step (vii), a step (viii) of removing the support (second substrate). The method for removing the support (second substrate) is not particularly limited. For example, the removal of the support (second substrate) may be carried out in the same manner as the removal of the substrate portion 301 of the first substrate in step (iii).

[0211] As described above, the optical waveguide 10 may further include a conductor layer such as a plating layer. Therefore, the method for manufacturing an optical waveguide of the present invention may further include, after step (vii) (or step (viii)), a step (ix) of forming a conductor layer so as to be in contact with the cladding layer 200. The location where the conductor layer is formed is not particularly limited as long as the conductor layer is in contact with the cladding layer 200. When the optical waveguide 10 includes a conductor layer, the conductor layer is preferably formed by plating. Furthermore, before forming the conductor layer by plating, a roughening treatment may be performed on the surface of the cladding layer 200 that is in contact with the conductor layer (hereinafter, sometimes referred to as "surface 200S").

[0212] The procedure and conditions for the roughening treatment are not particularly limited. For example, the surface 200S can be roughened by performing a swelling treatment with a swelling liquid, a roughening treatment with an oxidizing agent, and a neutralization treatment with a neutralizing liquid in this order.

[0213] Examples of swelling solutions used in the roughening treatment include alkaline solutions and surfactant solutions, with alkaline solutions being preferred. Examples of alkaline solutions include sodium hydroxide solutions and potassium hydroxide solutions. Examples of commercially available swelling solutions include "Swelling Dip Securigance P" and "Swelling Dip Securigance SBU" manufactured by Atotech Japan. The swelling treatment using a swelling solution is not particularly limited, but can be performed by, for example, immersing the surface 200S in a swelling solution at 30°C to 90°C for 1 to 20 minutes. From the viewpoint of suppressing swelling of the resin on the surface 200S to an appropriate level, it is preferable to immerse the surface of the cladding layer 200 that contacts the conductor layer in a swelling solution at 40°C to 80°C for 5 to 15 minutes.

[0214] An example of an oxidizing agent used in the roughening treatment is an alkaline permanganate solution prepared by dissolving potassium permanganate or sodium permanganate in an aqueous solution of sodium hydroxide. The roughening treatment using an oxidizing agent such as an alkaline permanganate solution is preferably carried out by immersing the insulating layer in an oxidizing agent solution heated to 60°C to 100°C for 10 minutes to 30 minutes. The concentration of permanganate in the alkaline permanganate solution is preferably 5% by mass to 10% by mass. Commercially available oxidizing agents include alkaline permanganate solutions such as "Concentrate Compact CP" and "Dosing Solution Securigance P" manufactured by Atotech Japan.

[0215] The neutralizing solution used in the roughening treatment is preferably an acidic aqueous solution, and a commercially available product such as "Reduction Solution Securigant P" manufactured by Atotech Japan, Inc. Treatment with a neutralizing solution can be carried out by immersing the surface that has been roughened with an oxidizing agent in a neutralizing solution at 30°C to 80°C for 5 to 30 minutes. From the standpoint of workability, etc., a method in which the object that has been roughened with an oxidizing agent is immersed in a neutralizing solution at 40°C to 70°C for 5 to 20 minutes is preferred.

[0216] The arithmetic mean roughness Ra of the surface 200S is preferably 500 nm or less, more preferably less than 400 nm, even more preferably 200 nm or less, and even more preferably less than 200 nm. The lower limit is not particularly limited, and may be, for example, 1 nm or more, 2 nm or more, etc.

[0217] After the roughening treatment is completed, a conductor layer is formed on the roughened surface 200S. Specifically, the surface 200S can be plated by a method such as a semi-additive method or a full-additive method to form a conductor layer having a desired wiring pattern. From the viewpoint of ease of manufacturing, the semi-additive method is preferable. An example of forming a conductor layer by a semi-additive method is shown below.

[0218] A plating seed layer is formed on the surface 200S by electroless plating. Next, a mask pattern is formed on the formed plating seed layer, exposing a portion of the plating seed layer corresponding to the desired wiring pattern. After a metal layer is formed on the exposed plating seed layer by electrolytic plating, the mask pattern is removed. Thereafter, unnecessary plating seed layer is removed by etching or the like, thereby forming a conductor layer having the desired wiring pattern.

[0219] As described above, the optical waveguide 10 may include a protective layer that protects the core layer 100 and the cladding layer 200. Therefore, the method for manufacturing an optical waveguide of the present invention may further include a step of forming a protective layer. Furthermore, the method for manufacturing an optical waveguide of the present invention may include a step of dicing the manufactured optical waveguide 10.

[0220] The method for manufacturing the optical waveguide 10 may further include any optional steps in combination with the steps described above.

[0221] In the method for manufacturing an optical waveguide of the present invention, the above-described steps may be repeated. For example, the above-described steps may be repeated to manufacture an optical waveguide with a multilayer structure in which core layers and clad layers are alternately provided in the thickness direction.

[0222] [Opto-electrical Hybrid Board and Manufacturing Method Thereof] 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.

[0223] 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.

[0224] 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, 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 thereto, and it is preferable that it be capable of transmitting light with wavelengths of, for example, 1300 nm to 1320 nm. The optical waveguides according to the above-described embodiments are capable of transmitting light with these wavelengths.

[0225] 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 optical-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.

[0226] 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.

[0227] 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 the core resin composition of the present invention for the core, a fine core can be formed, 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.

[0228] 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.

[0229] [Semiconductor Device] A semiconductor device according to one embodiment of the present invention includes the above-described opto-electric hybrid substrate. Examples of such semiconductor devices include various semiconductor devices used in electrical products (e.g., computers, mobile phones, smartphones, tablet devices, wearable devices, digital cameras, medical equipment, and televisions) and vehicles (e.g., motorcycles, automobiles, trains, ships, and aircraft).

[0230] The present invention will be specifically described below with reference to examples. However, 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 temperature and pressure conditions were room temperature (23°C) and atmospheric pressure (1 atm), unless otherwise specified.

[0231] Production Example 1: Production of Cladding Resin Composition and Resin Sheet 1 23 parts of a phenoxy resin ("YX7200B35" manufactured by Mitsubishi Chemical Corporation, a phenoxy resin having a biphenyl structure and a structure derived from bisphenol TMC, a methyl ethyl ketone solution with 35% non-volatile components), 20 parts of an epoxy resin ("YX7760" manufactured by Mitsubishi Chemical Corporation, a bisphenol AF type epoxy resin, epoxy equivalent 245 g / eq.), and 1.4 parts of a cyclic carbonate compound (5,5-dimethyl-4-(propan-2-yl)-1,3-dioxane-2-one manufactured by JNC Corporation) were mixed, and the resulting mixture was heated and dissolved to obtain a dissolved composition. 0.36 parts of a curing accelerator ("TBP-DA" manufactured by Hokko Chemical Industry Co., Ltd., tetrabutylphosphonium decanoate) was mixed with the resulting dissolved composition to obtain Resin Varnish 1.

[0232] A polyethylene terephthalate film ("NSH" manufactured by Fujimori Kogyo Co., Ltd., thickness 50 μm) treated with a non-silicone release agent was prepared as a support. Resin varnish 1 was uniformly applied to the release layer of the support using a die coater so that the thickness of the resin composition layer after drying would be 50 μm. Resin varnish 1 was then dried at 100°C for 5 minutes to produce a resin sheet 1 including a support and a cladding resin composition layer (thickness 50 μm).

[0233] <Production Example 2: Production of core resin composition and resin sheet 2> 23 parts of phenoxy resin ("YX7200B35" manufactured by Mitsubishi Chemical Corporation), 18 parts of epoxy resin ("YX7760" manufactured by Mitsubishi Chemical Corporation), and 1.4 parts of a cyclic carbonate compound (5,5-dimethyl-4-(propan-2-yl)-1,3-dioxane-2-one manufactured by JNC Corporation) were mixed, and the resulting mixture was heated and dissolved to obtain a dissolved composition. 0.36 parts of a curing accelerator ("TBP-DA" manufactured by Hokko Chemical Industry Co., Ltd., tetrabutylphosphonium decanoate) was mixed with the resulting dissolved composition to obtain resin varnish 2.

[0234] A polyethylene terephthalate film ("NSH" manufactured by Fujimori Kogyo Co., Ltd., thickness 50 μm) treated with a non-silicone release agent was prepared as a support. Resin varnish 2 was uniformly applied to the release layer of the support using a die coater so that the thickness of the resin composition layer after drying would be 50 μm. The resin varnish was then dried at 100°C for 5 minutes to produce a resin sheet 2 including a support and a core resin composition layer (thickness 50 μm).

[0235] Example 1: Manufacturing of optical waveguide (1) Preparation of first substrate An 8-inch silicon wafer substrate (thickness 725 μm) with a seed layer (metal layer) of Ti / Cu=50 / 200 nm was prepared as a first substrate.

[0236] (2) Formation of Wiring Pattern A copper wiring pattern was formed on the seed layer of the substrate according to the semi-additive method. Specifically, the following operations were performed. A dry film (photosensitive resist film, "RY-5115" manufactured by Resonac Corporation) was laminated on the seed layer of the substrate. The dry film was laminated using a batch-type vacuum pressure laminator ("V-160" manufactured by Nikko Materials Co., Ltd.) by reducing the pressure for 30 seconds to adjust the air pressure to 13 hPa or less, and then pressing the film at a temperature of 100°C and a pressure of 0.4 MPa for 30 seconds. Next, a glass mask (exposure mask) on which a wiring pattern (L / S = 10 μm / 500 μm) was formed was placed on the dry film and irradiated with light using a projection exposure machine ("UX-2240" manufactured by Ushio Inc.). Next, a 1% sodium carbonate solution at 30°C was sprayed for 60 seconds at a spray pressure of 0.15 MPa. The film was then washed with water and developed. The dry film was developed to form a comb-tooth pattern (L / S=10 / 500 μm) wiring pattern with the seed layer exposed. After development, electrolytic copper plating was performed to form an electrolytic copper plating layer with a thickness of 11 μm on the seed layer.

[0237] Using a silica solution (average particle size of 85 nm) as a slurry and a CMP urethane pad, the dry film and a portion of the electrolytic copper plating layer on the substrate were polished for 7 minutes to align the height of the electrolytic copper plating layer and smooth the surface. This polishing was performed in the stacking direction under conditions of a pressure of 3 psi (approximately 20.7 kPa), a sample rotation speed of 30 rpm, and a platen rotation speed of 31 rpm. The dry film was then peeled off to obtain a copper wiring pattern. This substrate is designated Substrate A.

[0238] (3) Lamination of Resin Sheet 1 (Lamination of Cladding Resin Composition Layer) The resin sheet 1 obtained in Production Example 1 above was laminated onto the wiring pattern of Substrate A so that the cladding resin composition layer and the wiring pattern were in contact. Lamination of the resin sheet 1 was carried out using a batch-type vacuum pressure laminator ("V-160" manufactured by Nikko Materials Co., Ltd.) by reducing the pressure for 30 seconds to adjust the air pressure to 13 hPa or less, and then pressing the sheets together at a temperature of 80°C and a pressure of 0.3 MPa for 30 seconds. After lamination, the support in the resin sheet 1 was peeled off. This peeling resulted in a substrate B having a layer structure of cladding resin composition layer (surface layer) / copper wiring pattern and cladding resin composition layer (intermediate layer) / seed layer (metal layer) / silicon wafer.

[0239] (4) Lamination of Second Substrate and Curing of Cladding Resin Composition Layer (Formation of First Cladding Layer) A glass wafer (8 inches thick) was laminated as a second substrate onto the cladding resin composition layer (surface layer) of Substrate B. Using a batch-type vacuum pressure laminator ("V-160" manufactured by Nikko Materials Co., Ltd.), the pressure was reduced for 30 seconds to adjust the air pressure to 13 hPa or less, and then pressure-bonded at a temperature of 80°C and a pressure of 0.3 MPa for 30 seconds. After laminating the glass wafer, the substrate was placed in an oven at 100°C and heated for 60 minutes, then transferred to an oven at 150°C and heated for 30 minutes to thermally cure the cladding resin composition layer. This curing formed a first cladding layer. This substrate was designated Substrate C.

[0240] (5) Removal of First Substrate: For Substrate C, the silicon wafer substrate as the first substrate was removed by polishing using a grinder (DISCO Corporation, "DAG810"). The polishing operation was completed when the Ti / Cu seed layer (metal layer) in the first substrate was exposed over the entire surface. The substrate obtained by this operation was designated Substrate D.

[0241] (6) Formation of recesses corresponding to the wiring pattern The substrate D was subjected to etching using an etching solution to remove the copper wiring pattern and the seed layer (metal layer). The Ti etching operation was performed using "Meltex" "Melstrip Ti-3991": ２ O ２ A mixed solution of titanium and pure water (1:1:2) was used as the titanium etching solution, and titanium etching was carried out at room temperature. Cu etching was carried out at room temperature using a mixed solution of Mitsubishi Gas Chemical Company's "WLC-C2" and pure water (1:1) as the copper etching solution. By these etching operations, a substrate E having recesses corresponding to the wiring pattern was obtained.

[0242] (7) Lamination of Resin Sheet 2 (Lamination of Core Resin Composition Layer) and Curing of Core Resin Composition Layer (Formation of Core Underlayer) The resin sheet 2 obtained in Production Example 2 above was laminated on the recessed side of the substrate E so that the core resin composition layer was embedded in the recessed portion. The resin sheet 2 was laminated using a batch-type vacuum pressure laminator ("V-160" manufactured by Nikko Materials Co., Ltd.) by reducing the pressure for 30 seconds to adjust the air pressure to 13 hPa or less, and then pressing at a temperature of 80 ° C and a pressure of 0.3 MPa for 30 seconds. After laminating the resin sheet 2, it was placed in an oven at 100 ° C and heated for 60 minutes to cure the core resin composition layer. By such curing, a core underlayer was formed.

[0243] (8) Formation of Core Layer (Polishing of Core Underlayer) A portion of the core underlayer was polished using a silica solution (average particle size of silica particles in the slurry: 85 nm) and a CMP urethane pad. This polishing was performed in the stacking direction under conditions of a pressure of 3 psi (approximately 20.7 kPa), a sample rotation speed of 30 rpm, and a platen rotation speed of 31 rpm. The polishing was terminated when the first cladding layer and the core underlayer were flush with each other. This polishing formed a core layer. This substrate is designated Substrate F.

[0244] (9) Lamination of Resin Sheet 1 and Curing of Cladding Resin Composition Layer (Formation of Second Cladding Layer) The resin sheet 1 obtained in Production Example 1 above was laminated on the substrate F so that the cladding resin composition layer was in contact with the core layer and the first cladding layer. Lamination of the resin sheet 1 was performed using a batch-type vacuum pressure laminator (Nikko Materials Co., Ltd., "V-160") by reducing the pressure for 30 seconds to 13 hPa or less, followed by pressure bonding at a temperature of 80°C and a pressure of 0.3 MPa for 30 seconds. After laminating the resin sheet 1, the laminate was placed in a 100°C oven and heated for 60 minutes, then transferred to a 150°C oven and heated for 30 minutes to thermally cure the cladding resin composition layer. This curing formed a second cladding layer. Through the above operations, an optical waveguide with an L / S = 10 μm / 500 μm was obtained using a thermosetting resin.

[0245] Test Example 1: Measurement of Minimum Melt Viscosity The melt viscosity of the resin composition layers in the resin sheets 1 and 2 obtained in Production Examples 1 and 2 above was measured using a dynamic viscoelasticity measuring device (Rheosol-G3000 manufactured by U.B.M.). This measurement was performed on a 1 g sample taken from the resin composition layer using parallel plates with a diameter of 18 mm. The measurement conditions were a starting temperature of 60°C to 200°C, a heating rate of 5°C / min, a measurement temperature interval of 2.5°C, and an oscillation frequency of 1 Hz / deg. The minimum melt viscosity was calculated from the obtained measured melt viscosity values.

[0246] <Test Example 2: Measurement of tensile modulus> The resin composition layers in the resin sheets 1 and 2 obtained in Production Examples 1 and 2 above were heated at 150°C for 60 minutes to cure the resin composition layers. The support was peeled off from the resin sheet to obtain a cured resin composition layer. The cured product was cut into a dumbbell-shaped No. 1 test piece to obtain a test specimen. The tensile strength of the test piece was measured using a tensile tester "RTC-1250A" manufactured by Orientec Co., Ltd., and the tensile modulus at 23°C was determined. The measurement was carried out in accordance with JIS K7127. The measurement was carried out five times, and the average value of the five points was calculated.

[0247] The results of Test Examples 1 and 2 are shown in Table 1 below.

[0248]

[0249] Test Example 3: Evaluation Test of Embeddability A silicon wafer having a recess (trench structure) with a width of 5 μm and a depth (thickness) of 5 μm was prepared. The resin sheet 2 obtained in Production Example 2 above was laminated so that the core resin composition layer was embedded in the recess of the silicon wafer. The resin sheet 2 was laminated using a batch-type vacuum pressure laminator ("V-160" manufactured by Nikko Materials Co., Ltd.) by reducing the pressure for 30 seconds to adjust the air pressure to 13 hPa or less, and then pressing at a temperature of 80°C and a pressure of 0.3 MPa for 30 seconds. After laminating the resin sheet 2, it was placed in an oven at 100°C and heated for 60 minutes to harden the core resin composition layer. This hardening formed a core underlayer. This substrate was designated as evaluation substrate α.

[0250] A cross-section of the evaluation substrate α was observed using a FIB-SEM composite device (Hitachi High-Tech Science Corporation's "ETHOS NX5000"). Specifically, an FIB (focused ion beam) was used to cut out a cross section parallel to the thickness direction of the core underlayer (a cross section parallel to the stacking direction). This cross section was observed using an SEM. It was confirmed that there were no voids with a diameter of 1 μm or more in the observed image. From this test, it can be seen that the optical waveguide manufacturing method of the present invention can obtain an optical waveguide with excellent embeddability.

[0251] Test Example 4: Evaluation test of polishability of cladding layer For substrate E obtained in "(6) Formation of recesses" above, a platinum film was formed by vapor deposition on the recess side of substrate E. Except for this vapor deposition operation, the same operations as "(7) Lamination of resin sheet 2 (lamination of core resin composition layer) and curing of core resin composition layer (formation of core underlayer)" and "(8) Formation of core layer (polishing of core underlayer)" were performed to obtain evaluation substrate β, on which the interface between the core layer and the first cladding layer could be confirmed.

[0252] A cross-section of the evaluation substrate β was observed using a FIB-SEM composite device ("ETHOS NX5000" manufactured by Hitachi High-Tech Science Corporation). Specifically, an FIB (focused ion beam) was used to cut out the core layer so that a cross-section parallel to the thickness direction of the cured product (a cross-section parallel to the stacking direction) appeared. This cross-section was observed using an SEM. In the observed image, it was confirmed that no steps of 200 nm or more were present in the core layer and the first clad layer. From this test, it can be seen that the method for manufacturing an optical waveguide of the present invention can obtain an optical waveguide with excellent polishing properties for the clad layer.

[0253] Test Example 5: Evaluation Test of Dimensional Stability of Core Pattern A sputtered film of Ti / Cu=20 / 100 nm was formed by sputtering on the substrate E obtained in the above "(6) Formation of Recesses." Except for the operation of forming the sputtered film, the same operations as "(7) Lamination of Resin Sheet 2 (Lamination of Core Resin Composition Layer) and Curing of Core Resin Composition Layer (Formation of Core Underlayer)," "(8) Formation of Core Layer (Polishing of Core Underlayer)," and "(9) Lamination of Resin Sheet 1 and Curing of Cladding Resin Composition Layer (Formation of Second Cladding Layer)" were performed to obtain an evaluation substrate γ in which the width and height of the core pattern could be confirmed. A cross-section of the evaluation substrate γ was observed using a FIB-SEM composite instrument ("ETHOS NX5000" manufactured by Hitachi High-Tech Science Corporation). Specifically, a focused ion beam (FIB) was used to carve out a cross section parallel to the thickness direction of the core pattern (a cross section parallel to the lamination direction). This cross section was observed using an SEM. The width and height of the core pattern were measured at five arbitrary locations in the observed image. These measurements confirmed that the width and height of the core pattern were 10 μm±1 μm at all five locations. From this test, it can be seen that the method for manufacturing an optical waveguide of the present invention can produce an optical waveguide with excellent dimensional stability.

[0254] 10 Optical waveguide 100 Core layer 100A Incident side end of core layer 100B Emission side end of core layer 100I Interface between core layer and clad layer 110 Second resin composition layer 111 Core underlayer (cured second resin composition layer) 200 Clad layer 210 First resin composition layer 211 First clad layer (cured first resin composition layer) 220 Third resin composition layer 221 Second clad layer (cured third resin composition layer) 300 Substrate with metal layer (first substrate) 301 Substrate portion of first substrate 302 Metal layer 302S Portion on metal layer not covered by mask layer 310 Metal wiring pattern 400 Mask layer 500 Recess

Claims

1. A method for manufacturing an optical waveguide, comprising, in this order: (i) forming a metal wiring pattern on a metal layer of a substrate (first substrate) with a metal layer; (ii) forming a first resin composition layer from a cladding resin composition so as to contact the metal layer and the wiring pattern, and curing the first resin composition layer to form a first cladding layer; (iii) removing a substrate portion of the first substrate; (iv) removing the metal layer and the wiring pattern, and forming a recess corresponding to the wiring pattern; (v) forming a second resin composition layer from a core resin composition containing a thermosetting resin so as to contact the recess, and curing the second resin composition layer to form a core underlayer; (vi) removing a portion of the core underlayer and forming a core layer; and (vii) forming a third resin composition layer from a cladding resin composition so as to contact the core layer and the first cladding layer, and curing the third resin composition layer to form a second cladding layer.

2. The manufacturing method according to claim 1, wherein step (ii) comprises: (ii-1) joining a support (second substrate) to the first resin composition layer on the surface of the first resin composition layer opposite to the substrate with the metal layer (first substrate).

3. The manufacturing method according to claim 2, further comprising, after step (vii), a step (viii) of removing the support (second substrate).

4. The manufacturing method according to claim 2, wherein the support (second base material) is a glass substrate, a single crystal silicon substrate, or a silicon substrate provided with an inorganic film, and the silicon substrate provided with an inorganic film is provided with an inorganic film including a silicon oxide film on a surface that bonds with the first resin composition layer.

5. The manufacturing method according to claim 1, wherein the metal layer portion of the substrate with a metal layer (first substrate) contains copper.

6. The manufacturing method according to claim 1, wherein step (iv) comprises: (iv-1) removing the metal layer and the wiring pattern by wet treatment using an etching solution to form a recess.

7. The manufacturing method according to claim 1, wherein the substrate portion of the substrate with a metal layer (first substrate) is a glass substrate, a single crystal silicon substrate, or a silicon substrate provided with an inorganic film, and the silicon substrate provided with an inorganic film has an inorganic film containing a silicon oxide film between the metal layer and the silicon substrate.

8. The manufacturing method according to claim 1, wherein step (iii) comprises: (iii-1) peeling off the substrate portion of the first substrate.

9. The manufacturing method according to claim 1, wherein step (iii) comprises: (iii-2) polishing the substrate portion of the first substrate.

10. The manufacturing method according to claim 1, wherein step (vi) comprises: (vi-1) polishing a portion of the core underlayer by chemical mechanical polishing (CMP) to form a core layer.

11. The manufacturing method according to claim 1, wherein the cladding resin composition comprises a thermosetting resin.

12. The manufacturing method according to claim 1, further comprising the step of (ii') planarizing the surface of the wiring pattern by chemical mechanical polishing (CMP) after step (i) and before step (ii).

13. The manufacturing method according to claim 1, wherein the width of the core layer is 10 μm or less.

14. The manufacturing method according to claim 1, wherein the optical waveguide manufactured is a single-mode optical waveguide.

15. At a wavelength of 1310 nm, the refractive index of the cured core resin composition is n ｃｏｒｅ The refractive index of the cured product of the cladding resin composition is n ｃｌａｄ In this case, n ｃｏｒｅ -n ｃｌａｄ The method according to claim 1 , wherein the relationship of ≦0.1 is satisfied.

16. The manufacturing method according to claim 1, wherein the core resin composition contains one or more resins selected from the group consisting of epoxy resins, (meth)acrylic resins, phenolic resins, and silicone resins.

17. The manufacturing method according to claim 1, wherein the cladding resin composition contains one or more resins selected from the group consisting of epoxy resins, (meth)acrylic resins, phenolic resins, and silicone resins.

18. An optical / electrical hybrid board comprising an optical waveguide manufactured by the method according to any one of claims 1 to 17.

19. A semiconductor device comprising the optical-electrical hybrid substrate according to claim 18.

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