Composition for clad, composition set, optical waveguide, and electronic device

Abstract

To provide a composition for a clad from which an optical waveguide having improved thermal reliability can be obtained.SOLUTION: A composition for a clad, which is usable in a clad of an optical waveguide, contains a cyclic olefin resin (A), and polyfunctional (meth)acrylate (B).SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a composition for a cladding, a composition set, an optical waveguide, and an electronic device.

Background Art

[0002] In recent years, in information communication devices, there has been a demand for components that can achieve more advanced information communication such as increased information capacity and higher information communication speed. As one of such components, optical waveguides have been studied.

[0003] As a technology of an optical waveguide, for example, the technology described in Patent Document 1 can be mentioned.

[0004] Patent Document 1 describes an optical waveguide formed by laminating a core layer made of a polymer and a cladding layer made of a polymer on a substrate, wherein the core layer is sandwiched from a direction parallel to the surface of the substrate by a cladding layer having a refractive index smaller than that of the cladding layer sandwiching the core layer from a direction perpendicular to the surface of the substrate. According to the optical waveguide of Patent Document 1, it is described that an optical waveguide with less polarization dependence can be realized even when using a polymer with a large birefringence such as polyimide.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] The present invention provides a composition for a cladding capable of obtaining an optical waveguide with improved thermal reliability.

Means for Solving the Problems

[0007] According to the present invention, there are provided a clad composition, a composition set, an optical waveguide, and an electronic device as described below.

[0008] [1] A clad composition capable of being used for a clad of an optical waveguide, comprising a cyclic olefin resin (A) and a polyfunctional (meth)acrylate (B), the clad composition. [2] The cyclic olefin resin (A) is the clad composition according to [1] above, comprising a structural unit represented by the following formula (1) and a structural unit represented by the following formula (2).

Chemical formula

Chemical formula

Chemical formula

Chemical formula

[10] The clad composition according to any one of [1] to [9], further comprising an organic solvent (D).

[11] The clad composition according to any one of [1] to

[10] , which is in the form of a varnish.

[12] The clad composition according to any one of [1] to

[11] , having a refractive index at 30 °C and a wavelength of 1310 nm of 1.470 or more and 1.530 or less.

[13] The clad composition according to any one of [1] to

[12] , having an absorbance at 22 °C and a wavelength of 1310 nm of 0.030 or more and 0.070 or less.

[14] The clad composition according to any one of [1] to

[13] , and A composition set including a core composition that can be used for the core of an optical waveguide.

[15] The composition set according to

[14] , wherein the core composition includes a polyimide resin and a polyfunctional (meth)acrylate.

[16] The composition set according to

[14] , wherein the core composition includes an epoxy resin and a phenoxy resin.

[17] An optical waveguide including a clad made of the clad composition according to any one of [1] to

[13] .

[18] Comprising a silicon photonics device, The silicon photonics device includes the optical waveguide according to

[17] , an electronic device.

Advantages of the Invention

[0009] According to the present invention, it is possible to provide a clad composition capable of obtaining an optical waveguide with improved thermal reliability.

Brief Description of the Drawings

[0010]

Figure 1

Embodiments for Carrying Out the Invention

[0011] Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the drawings are schematic diagrams and do not match the actual dimensional ratios. The numerical range "A to B" represents A or more and B or less unless otherwise specified. (Meth)acrylate is a concept including both acrylate and methacrylate. Also, (meth)acryloyl group is a concept including both acryloyl group and methacryloyl group.

[0012] An optical waveguide may be formed, for example, on a chip (such as a silicon chip or the like). Since the chip may generate heat, the optical waveguide formed on the chip may be required to have thermal reliability. Here, in this specification, a high thermal reliability of the optical waveguide means that when an environmental test (for example, under the conditions of 125°C and 1000 hours) is performed on the optical waveguide, the difference between the propagation loss of the optical waveguide after the environmental test and the propagation loss of the optical waveguide before the environmental test is small.

[0013] The present invention provides a composition for a cladding capable of obtaining an optical waveguide with improved thermal reliability.

[0014] [Composition for Cladding] The composition for a cladding of the present embodiment is a composition for a cladding that can be used for the cladding of an optical waveguide, and includes a cyclic olefin resin (A) and a polyfunctional (meth)acrylate (B).

[0015] The refractive index of the composition for a cladding of the present embodiment at 30°C and a wavelength of 1310 nm is preferably 1.530 or less, more preferably 1.520 or less, still more preferably 1.510 or less, from the viewpoint of further improving the optical propagation efficiency of the optical waveguide, and the lower limit value is not particularly limited, but may be, for example, 1.470 or more, or may be 1.490 or more. Here, the refractive index of the composition for a cladding at 30°C and a wavelength of 1310 nm means the value of the refractive index calculated by the method described in the examples.

[0016] The absorbance of the composition for a cladding of the present embodiment at 22°C and a wavelength of 1310 nm is preferably 0.070 or less, more preferably 0.065 or less, still more preferably 0.055 or less, and the lower limit value is not particularly limited, but may be, for example, 0.030 or more, or may be 0.040 or more. Here, the absorbance of the composition for a cladding at 22°C and a wavelength of 1310 nm means the value of the absorbance calculated by the method described in the examples.

[0017] The shape of the composition for the clad of the present embodiment is not particularly limited, and may be, for example, a varnish shape, a film shape, a film shape, a sheet shape, etc., but preferably a varnish shape.

[0018] Hereinafter, each constituent component of the composition for the clad of the present embodiment will be described.

[0019] <Cyclic olefin resin (A)> The composition for the clad of the present embodiment contains a cyclic olefin resin (A).

[0020] The cyclic olefin resin (A) of the present embodiment preferably contains a structural unit represented by formula (1) and a structural unit represented by formula (2).

[0021] The cyclic olefin resin (A) preferably contains a structural unit represented by formula (1).

[0022]

Chemical formula

[0023] In formula (1), R 1 , R 2 , R 3 and R 4 are each independently a hydrogen atom or an organic group having 1 to 30 carbon atoms, and a1 is 0, 1 or 2.

[0024] In formula (1), R 1 , R 2 , R 3 and R 4 Among them, the organic group having 1 to 30 carbon atoms includes, for example, a substituted or unsubstituted, linear or branched alkyl group having 1 to 30 carbon atoms, and more specifically, an alkyl group, an alkenyl group, an alkynyl group, an alkylidene group, an aryl group, an aralkyl group, an alkaryl group, a cycloalkyl group, an alkoxy group, a heterocyclic group, a carboxyl group, etc.

[0025] Examples of the alkyl group include at least one selected from the group consisting of a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, a pentyl group, a neopentyl group, a hexyl group, a heptyl group, an octyl group, a nonyl group, and a decyl group, etc. Examples of the alkenyl group include at least one selected from the group consisting of an allyl group, a pentenyl group, and a vinyl group, etc. Examples of the alkynyl group include an ethynyl group, etc. Examples of the alkylidene group include at least one selected from the group consisting of a methylidene group and an ethylidene group, etc. Examples of the aryl group include at least one selected from the group consisting of a tolyl group, a xylyl group, a phenyl group, a naphthyl group, and an anthracenyl group, etc. Examples of the aralkyl group include at least one selected from the group consisting of a benzyl group and a phenethyl group, etc. Examples of the alkaryl group include at least one selected from the group consisting of a tolyl group and a xylyl group, etc. Examples of the cycloalkyl group include at least one selected from the group consisting of an adamantyl group, a cyclopentyl group, a cyclohexyl group, and a cyclooctyl group, etc. Examples of the alkoxy group include at least one selected from the group consisting of a methoxy group, an ethoxy group, an n-propoxy group, an isopropoxy group, an n-butoxy group, a sec-butoxy group, an isobutoxy group, a tert-butoxy group, an n-pentyloxy group, a neopentyloxy group, and an n-hexyloxy group, etc.

[0026] In formula (1), R 1 , R 2 , R 3 and R 4 are each independently preferably a hydrogen atom or an alkyl group, more preferably a hydrogen atom. Note that R 1 , R2 , R 3 and R 4 The hydrogen atoms in the organic group having 1 to 30 carbon atoms of R 1 , R 2 , R 3 and R 4 may be substituted by any atomic group. For example, they may be substituted by a fluorine atom, a hydroxyl group, a carboxyl group, etc. More specifically, as the organic group having 1 to 30 carbon atoms of R

[0027] In formula (1), a1 is preferably 0 or 1, more preferably 0.

[0028] When the total of all structural units in the cyclic olefin resin (A) is 100 mol%, the content of the structural unit represented by formula (1) in the cyclic olefin resin (A) is preferably 10 mol% or more and 90 mol% or less, more preferably 30 mol% or more and 70 mol% or less, still more preferably 40 mol% or more and 60 mol% or less.

[0029] The cyclic olefin resin (A) preferably contains a structural unit represented by formula (2).

[0030]

Chemical formula

[0031] In formula (2), R 11 is a group containing a terminal reactive unsaturated double bond, and R 21 is a hydrogen atom or an organic group having 1 to 3 carbon atoms.

[0032] In formula (2), R 11 is, for example, any one selected from the group consisting of a group containing a vinyl group, a group containing a vinylidene group, a group containing an acryloyl group, and a group containing a methacryloyl group, etc., and is preferably any one selected from the group consisting of a group containing an acryloyl group and a group containing a methacryloyl group. In formula (2), R 21is preferably a hydrogen atom.

[0033] The structural unit represented by the formula (2) preferably contains at least one selected from the group consisting of the structural unit represented by the formula (2-1) and the structural unit represented by the formula (2-2).

[0034]

Chemical formula

[0035] In the formula (2-1), Z is a group containing one or more (meth)acryloyl groups.

[0036] In the formula (2-1), Q is any one selected from the group consisting of a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, and a substituted alkyl group having 1 to 6 carbon atoms, and is preferably a hydrogen atom. The alkyl group having 1 to 6 carbon atoms is, for example, any one selected from the group consisting of a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, a pentyl group, and a hexyl group. The substituent of the substituted alkyl group having 1 to 6 carbon atoms is, for example, at least one selected from the group consisting of a halogen atom, a hydroxyl group, a carboxyl group, an amino group, a cyano group, and a mercapto group.

[0037] In the formula (2-1), X is any one selected from the group consisting of an oxygen atom, an alkylene group having 1 to 4 carbon atoms, and a substituted alkylene group having 1 to 4 carbon atoms. The alkylene group having 1 to 4 carbon atoms is, for example, any one selected from the group consisting of a methylene group, an ethylene group, a propylene group, and a butylene group. The substituent of the substituted alkylene group having 1 to 4 carbon atoms is at least one selected from the group consisting of a halogen atom, a hydroxyl group, a carboxyl group, an amino group, a cyano group, and a mercapto group.

[0038] In formula (2-1), when Q is an alkyl group and X is an alkylene group, any carbon atom of the alkyl group of Q and the alkylene group of X may be bonded to form a ring. Examples of the ring structure include at least one selected from the group consisting of a cyclopropane ring, a cyclobutane ring, a cyclopentane ring, a cyclohexane ring, a decalin ring, a benzene ring, and a naphthalene ring, etc.

[0039] In formula (2-1), R 21 is a hydrogen atom or an organic group having 1 to 3 carbon atoms, preferably a hydrogen atom.

[0040] In formula (2-1), preferably, in the embodiment where X is an alkylene group having 1 to 4 carbon atoms and Z is a (meth)acryloyloxy group, or in the embodiment where X is an oxygen atom and Z is a (meth)acryloyl group.

[0041]

Chemical formula

[0042] In formula (2-2), R s is a group represented by formula (2a), and R 21 [[ID=

[26] is a hydrogen atom or an organic group having 1 to 3 carbon atoms. In formula (2-2), R 21 is preferably a hydrogen atom.

[0043]

Chemical formula

[0044] In formula (2a), X 10 is a divalent organic group, and R is a hydrogen atom or a methyl group.

[0045] In formula (2a), X 10 preferably has 1 to 30 carbon atoms, more preferably 1 to 20 carbon atoms, and even more preferably 1 to 10 carbon atoms. In formula (2a), X 10is a group containing at least one selected from the group consisting of, for example, an alkylene group, a cycloalkylene group, an arylene group, an ether group, a carbonyl group, a carboxy group, etc., preferably an alkylene group, more preferably a linear alkylene group having 3 to 6 carbon atoms. The alkylene group may be substituted with any substituent, and examples of the substituent include at least one selected from the group consisting of an alkyl group, an aryl group, an alkoxy group, an aryloxy group, etc.

[0046] When the total of all structural units in the cyclic olefin resin (A) is 100 mol%, the content of the structural unit represented by the formula (2) in the cyclic olefin resin (A) is preferably 10 mol% or more and 50 mol% or less, more preferably 15 mol% or more and 40 mol% or less, still more preferably 20 mol% or more and 35 mol% or less.

[0047] The cyclic olefin resin (A) preferably further contains a structural unit represented by the formula (3).

[0048] [Chemical formula]

[0049] In the formula (3), R 22 is a hydrogen atom or an organic group having 1 to 3 carbon atoms, preferably a hydrogen atom. Examples of the organic group having 1 to 3 carbon atoms include a methyl group, an ethyl group, an n-propyl group, and an isopropyl group.

[0050] When the total of all structural units in the cyclic olefin resin (A) is 100 mol%, the content of the structural unit represented by the formula (3) in the cyclic olefin resin (A) is preferably 10 mol% or more and 50 mol% or less, more preferably 15 mol% or more and 40 mol% or less, still more preferably 20 mol% or more and 35 mol% or less.

[0051] The cyclic olefin resin (A) preferably further contains a structural unit represented by the formula (4).

[0052]

Chem.

[0053] In formula (4), R 21 and R 22 are each independently a hydrogen atom or an organic group having 1 to 3 carbon atoms, preferably a hydrogen atom. Examples of the organic group having 1 to 3 carbon atoms include a methyl group, an ethyl group, an n-propyl group, and an isopropyl group.

[0054] When the total of all structural units in the cyclic olefin resin (A) is 100 mol%, the content of the structural unit represented by formula (4) in the cyclic olefin resin (A) is preferably 3 mol% or more and 40 mol% or less, more preferably 10 mol% or more and 30 mol% or less.

[0055] The cyclic olefin resin (A) preferably contains a cyclic olefin resin (A1) and a cyclic olefin resin (A2). The cyclic olefin resin (A1) contains a structural unit represented by formula (1), a structural unit represented by formula (2-1), and a structural unit represented by formula (2-2). The cyclic olefin resin (A2) contains a structural unit represented by formula (1) and a structural unit represented by formula (2-2), and does not contain a structural unit represented by formula (2-1).

[0056] When the total of the cyclic olefin resin (A1) and the cyclic olefin resin (A2) in the clad composition of the present embodiment is 100 parts by mass, the content of the cyclic olefin resin (A1) in the clad composition is preferably 10 parts by mass or more and 90 parts by mass or less, more preferably 20 parts by mass or more and 80 parts by mass or less.

[0057] The weight average molecular weight (Mw) of the cyclic olefin resin (A) is, from the viewpoint of further improving the solubility in an organic solvent, for example, 6,000 or more and 30,000 or less, preferably 7,000 or more and 25,000 or less, and more preferably 8,000 or more and 20,000 or less. The weight average molecular weight (Mw) of the cyclic olefin resin can be determined by gel permeation chromatography (GPC) using polystyrene as a standard substance. In addition, when the cyclic olefin resin (A) contains two or more kinds of cyclic olefin resins, it is sufficient that the weight average molecular weight (Mw) of at least one kind of cyclic olefin resin is within the above range.

[0058] The content of the cyclic olefin resin (A) in the clad composition of the present embodiment is preferably 50% by mass or more, more preferably 60% by mass or more, still more preferably 70% by mass or more, and preferably 90% by mass or less, more preferably 85% by mass or less, still more preferably 80% by mass or less, when the total solid content in the clad composition is 100% by mass. Here, in the present specification, the total solid content in the composition means all components that remain as solid components in the cured product composed of the composition.

[0059] The cyclic olefin resin (A) can be produced, for example, by a known method, and more specifically, it can be produced by polymerizing monomers capable of forming each structural unit by an arbitrary method. Examples of the monomer capable of forming the structural unit represented by the formula (1) include 2-norbornene and the like. Examples of the monomer capable of forming the structural unit represented by the formula (4) include maleic anhydride and the like. The structural unit represented by the formula (2) can be formed, for example, by ring-opening the structural unit represented by the formula (4) and reacting it with 2-hydroxyethyl methacrylate, glycidyl methacrylate, or the like. The structural unit represented by the formula (3) can be formed, for example, by ring-opening the structural unit represented by the formula (4) and adding a proton.

[0060] The cyclic olefin resin (A) may be a single type of cyclic olefin resin or may contain two or more types of cyclic olefin resins.

[0061] <Polyfunctional (meth)acrylate (B)> The composition for a clad of the present embodiment contains a polyfunctional (meth)acrylate (B). In the present specification, the polyfunctional (meth)acrylate (B) means a (meth)acrylate compound having two or more (meth)acryloyl groups in one molecule.

[0062] The polyfunctional (meth)acrylate (B) preferably contains a (meth)acrylate compound (B1) having 5 or more functional groups. The number of functional groups of the (meth)acrylate compound (B1) is, for example, 11 or less.

[0063] The polyfunctional (meth)acrylate (B) preferably contains a (meth)acrylate compound (B2) having 2 or more and 4 or less functional groups.

[0064] The polyfunctional (meth)acrylate (B) more preferably contains a (meth)acrylate compound (B1) having 5 or more functional groups and a (meth)acrylate compound (B2) having 2 or more and 4 or less functional groups.

[0065] When the total amount of the (meth)acrylate compound (B1) having 5 or more functional groups and the (meth)acrylate compound (B2) having 2 or more and 4 or less functional groups in the composition for a clad of the present embodiment is 100 parts by mass, the content of the (meth)acrylate compound (B1) having 5 or more functional groups is preferably 10 parts by mass or more and 90 parts by mass or less, more preferably 20 parts by mass or more and 80 parts by mass or less, and still more preferably 25 parts by mass or more and 75 parts by mass or less.

[0066] Specific examples of the polyfunctional (meth)acrylate (B) include, for example, polyol polyacrylates such as ethylene glycol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, ditrimethylolpropane tetra(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, etc.; epoxy acrylates such as di(meth)acrylate of bisphenol A diglycidyl ether, di(meth)acrylate of hexanediol diglycidyl ether, etc.; urethane (meth)acrylate obtained by the reaction of a polyisocyanate and a hydroxyl group-containing (meth)acrylate such as hydroxyethyl (meth)acrylate, etc.

[0067] Examples of commercially available products of the polyfunctional (meth)acrylate (B) include, for example, Aronix M-400, Aronix M-460, Aronix M-402, Aronix M-510, Aronix M-520 (manufactured by Toagosei Co., Ltd.), KAYARAD T-1420, KAYARAD DPHA, KAYARAD DPCA20, KAYARAD DPCA30, KAYARAD DPCA60, KAYARAD DPCA120 (manufactured by Nippon Kayaku Co., Ltd.), Viscoat #230, Viscoat #300, Viscoat #802, Viscoat #2500, Viscoat #1000, Viscoat #1080 (manufactured by Osaka Organic Chemical Industry Co., Ltd.), NK Ester A-BPE-10, NK Ester A-GLY-9E, NK Ester A-9550, NK Ester A-DPH (manufactured by Shin-Nakamura Chemical Co., Ltd.), etc.

[0068] When the content of the cyclic olefin resin (A) in the clad composition of this embodiment is 100 parts by mass, the content of the polyfunctional (meth)acrylate (B) in the clad composition is preferably 5 parts by mass or more and 100 parts by mass or less, more preferably 10 parts by mass or more and 70 parts by mass or less, and still more preferably 20 parts by mass or more and 50 parts by mass or less.

[0069] The polyfunctional (meth)acrylate (B) may be a single type of polyfunctional (meth)acrylate, or may contain two or more types of polyfunctional (meth)acrylates, but preferably contains two or more types of polyfunctional (meth)acrylates.

[0070] <Polymerization initiator (C)> The clad composition of this embodiment preferably further contains a polymerization initiator (C).

[0071] The polymerization initiator (C) is not particularly limited, and includes, for example, at least one selected from the group consisting of a photopolymerization initiator and a thermal polymerization initiator, preferably includes a photopolymerization initiator, and more preferably includes a photo radical polymerization initiator. The photo radical polymerization initiator includes, for example, at least one selected from the group consisting of an oxime ester compound, an alkylphenone compound, a benzophenone compound, a benzoin compound, a thioxanthone compound, a halomethylated triazine compound, a halomethylated oxadiazole compound, a biimidazole compound, a titanocene compound, a benzoic acid ester compound, and an acridine compound, and preferably includes an oxime ester compound.

[0072] When the content of the cyclic olefin resin (A) in the clad composition is 100 parts by mass, the content of the polymerization initiator (C) in the clad composition of this embodiment is preferably 0.5 part by mass or more and 20 parts by mass or less, more preferably 1 part by mass or more and 10 parts by mass or less, and still more preferably 2 parts by mass or more and 5 parts by mass or less.

[0073] The polymerization initiator (C) may be a single type of polymerization initiator, or may contain two or more types of polymerization initiators.

[0074] <Organic solvent (D)> The clad composition of this embodiment preferably further contains an organic solvent (D). When the clad composition contains an organic solvent (D), a varnish-like clad composition can be obtained.

[0075] The organic solvent (D) includes at least one selected from the group consisting of, for example, acetone, methyl ethyl ketone, toluene, propylene glycol methyl ethyl ether, propylene glycol dimethyl ether, propylene glycol 1-monomethyl ether 2-acetate, diethylene glycol ethyl methyl ether, diethylene glycol monoethyl ether acetate, diethylene glycol monobutyl ether acetate, benzyl alcohol, propylene carbonate, ethylene glycol diacetate, propylene glycol diacetate, propylene glycol monomethyl ether acetate, dipropylene glycol methyl-n-propyl ether, butyl acetate, γ-butyrolactone, methyl lactate, ethyl lactate, butyl lactate, and the like.

[0076] When the clad composition contains the organic solvent (D), the concentration of the total solid content of the clad composition is preferably 10% by mass or more and 50% by mass or less, more preferably 20% by mass or more and 45% by mass or less. When the concentration of the total solid content of the clad composition is within the above range, each component can be sufficiently dissolved or dispersed, the coatability of the composition can be further improved, and furthermore, the viscosity of the composition can be appropriately controlled.

[0077] The organic solvent (D) may be a single organic solvent or may contain two or more organic solvents.

[0078] <Adhesion aid> The clad composition of the present embodiment preferably further contains an adhesion aid. The adhesion aid preferably contains a coupling agent, more preferably a silane coupling agent.

[0079] When the content of the cyclic olefin resin (A) in the clad composition is 100 parts by mass, the content of the adhesion aid in the clad composition of the present embodiment is preferably 0.1 part by mass or more and 10 parts by mass or less, more preferably 0.3 part by mass or more and 5 parts by mass or less, and still more preferably 0.5 part by mass or more and 3 parts by mass or less.

[0080] The adhesion promoter may be one kind of adhesion promoter or may contain two or more kinds of adhesion promoters.

[0081] <Surfactant> The composition for the clad of the present embodiment preferably further contains a surfactant. By including a surfactant in the composition for the clad, the coatability of the composition can be further improved, and furthermore, the flatness of the coating film made of the composition can be further improved.

[0082] The surfactant contains at least one selected from the group consisting of, for example, fluorine-based surfactants, silicone-based surfactants, alkyl-based surfactants, and acrylic-based surfactants, and preferably contains a fluorine-based surfactant.

[0083] When the content of the cyclic olefin resin (A) in the composition for the clad of the present embodiment is 100 parts by mass, the content of the surfactant in the composition for the clad is preferably 0.1 part by mass or more and 10 parts by mass or less, more preferably 0.3 part by mass or more and 5 parts by mass or less, and still more preferably 0.5 part by mass or more and 3 parts by mass or less.

[0084] The surfactant may be one kind of surfactant or may contain two or more kinds of surfactants.

[0085] <Other components> The composition for the clad of the present embodiment may further contain other components. Examples of the other components include sensitizers, fillers such as silica, defoamers, leveling agents, crosslinking aids, and the like. The content of the other components is an appropriate amount.

[0086] When the total content of the cyclic olefin resin (A) and the polyfunctional (meth)acrylate (B) in the composition for the clad of the present embodiment is 100% by mass of all the components in the composition for the clad, it is preferably 10% by mass or more and 60% by mass or less, more preferably 20% by mass or more and 50% by mass or less, and still more preferably 25% by mass or more and 45% by mass or less.

[0087] When the total content of the cyclic olefin resin (A) and the polyfunctional (meth)acrylate (B) in the clad composition of the present embodiment is based on 100% by mass of the total solid content in the clad composition, it is preferably 60% by mass or more, more preferably 70% by mass or more, still more preferably 80% by mass or more, still more preferably 85% by mass or more, still more preferably 90% by mass or more, and, for example, it may be 100% by mass or less, and may also be 98% by mass or less.

[0088] The clad composition of the present embodiment can be obtained, for example, by mixing each component.

[0089] [Composition set] The composition set of the present embodiment includes the clad composition of the present embodiment and a core composition that can be used for the core of an optical waveguide.

[0090] The core composition of the present embodiment is not particularly limited as long as it is a composition that can be used for the core of an optical waveguide, and may be, for example, a resin composition containing a resin used for the core of a known optical waveguide.

[0091] The shape of the core composition of the present embodiment is not particularly limited, and may be, for example, a varnish shape, a film shape, a film shape, a sheet shape, etc., but preferably a varnish shape.

[0092] The core composition of the present embodiment preferably contains a polyimide resin and a polyfunctional (meth)acrylate. When the total content of the polyimide resin and the polyfunctional (meth)acrylate in the core composition of the present embodiment is based on 100% by mass of all components in the core composition, it is preferably 10% by mass or more and 50% by mass or less, more preferably 15% by mass or more and 40% by mass or less, still more preferably 20% by mass or more and 30% by mass or less. When the total content of the polyimide resin and the polyfunctional (meth)acrylate in the core composition of the present embodiment is based on 100% by mass of the total solid content in the core composition, it is preferably 60% by mass or more and 95% by mass or less, more preferably 70% by mass or more and 90% by mass or less, and still more preferably 75% by mass or more and 85% by mass or less.

[0093] The polyimide resin contained in the core composition of the present embodiment is not particularly limited, but preferably contains a fluorine atom in the molecule.

[0094] As the polyfunctional (meth)acrylate contained in the core composition of the present embodiment, for example, the same polyfunctional (meth)acrylate (B) as that contained in the clad composition of the present embodiment can be used.

[0095] Another preferred embodiment of the core composition of the present embodiment includes an epoxy resin and a phenoxy resin. When the total content of the epoxy resin and the phenoxy resin in the core composition of the present embodiment is based on 100% by mass of all components in the core composition, it is preferably 10% by mass or more and 60% by mass or less, more preferably 20% by mass or more and 50% by mass or less, and still more preferably 25% by mass or more and 45% by mass or less. When the total content of the epoxy resin and the phenoxy resin in the core composition of the present embodiment is based on 100% by mass of the total solid content in the core composition, it is preferably 50% by mass or more and 95% by mass or less, more preferably 60% by mass or more and 90% by mass or less, and still more preferably 65% by mass or more and 85% by mass or less.

[0096] The epoxy resin contained in the core composition of the present embodiment is not particularly limited, but preferably contains two or more epoxy resins in one molecule. The epoxy resin preferably includes a phenol novolac type epoxy resin.

[0097] The phenoxy resin contained in the core composition of the present embodiment is not particularly limited, but preferably contains at least one selected from the group consisting of bisphenol A type phenoxy resin and copolymerized phenoxy resin of bisphenol A type and bisphenol F type.

[0098] The core composition of the present embodiment can be obtained, for example, by mixing each component.

[0099] [Optical waveguide] The optical waveguide of the present embodiment includes a cladding made of the cladding composition of the present embodiment.

[0100] FIG. 1 is a cross-sectional view schematically showing an example of the structure of the optical waveguide of the present embodiment. An example of the optical waveguide of the present embodiment will be described with reference to FIG. 1. In FIG. 1, an optical waveguide 100 is formed on a wafer 50. The optical waveguide 100 includes an undercladding 10, a core 20, and an overcladding 30.

[0101] <Core> The material constituting the core 20 is not particularly limited. For example, a material for forming a core of a known optical waveguide can be used, which may be an organic material or an inorganic material.

[0102] The core 20 may be composed of, for example, the core composition in the composition set of the present embodiment. The core composition for forming the core may be a cured product, a semi-cured product, or an uncured product, but preferably a cured product.

[0103] The thickness and line width of the core 20 are not particularly limited, but are preferably dimensions that satisfy the single-mode condition. The single-mode condition depends on the relative refractive index difference between the core and the cladding and the guided wavelength, but the thickness and line width of the core 20 are preferably 1 μm or more and 11 μm or less, more preferably 2 μm or more and 10 μm or less.

[0104] <Cladding> The underclad 10 and the overclad 30 will be described. Hereinafter, when simply referred to as "clad", it means a concept including both the underclad 10 and the overclad 30 without particular notice.

[0105] At least one selected from the group consisting of the underclad 10 and the overclad 30 is made of the clad composition of the present embodiment. As a preferred embodiment, there is an embodiment in which both the underclad 10 and the overclad 30 are made of the clad composition of the present embodiment. Also, as another preferred embodiment, there is an embodiment in which the overclad 30 is made of the clad composition of the present embodiment and the underclad 10 is made of a material other than the clad composition of the present embodiment.

[0106] The clad composition for forming the clad may be a cured product, a semi-cured product, or an uncured product, but is preferably a cured product.

[0107] As a material constituting the clad other than the clad composition of the present embodiment, for example, a material for forming a clad of a known optical waveguide can be used, which may be an organic material or an inorganic material. The clad may be composed of, for example, SiO2.

[0108] The thickness of the underclad 10 is not particularly limited, but is preferably 1 μm or more and 25 μm or less, more preferably 3 μm or more and 20 μm or less, and still more preferably 5 μm or more and 15 μm or less. The thickness of the overclad 30 from the surface of the underclad 10 is not particularly limited, but is preferably 3 μm or more and 50 μm or less, more preferably 5 μm or more and 40 μm or less, and still more preferably 10 μm or more and 30 μm or less. The thickness of the overclad 30 from the surface of the core 20 is not particularly limited, but is preferably 1 μm or more and 25 μm or less, more preferably 3 μm or more and 20 μm or less, and still more preferably 5 μm or more and 15 μm or less.

[0109] The optical waveguide 100 may further include components other than the underclad 10 , the core 20 , and the overclad 30 .

[0110] The method for manufacturing the optical waveguide 100 is not particularly limited, but may include, for example, the following steps (i) to (iii). (i) A varnish-like cladding composition is applied onto the wafer 50, dried to form an undercladding layer, and the undercladding layer obtained is cured to form the undercladding 10. (ii) A varnish-like core composition is applied onto the underclad 10, dried to form a core layer, and the resulting core layer is cured to form the core 20. (iii) A varnish-like clad composition is applied onto the core 20 and dried to form an overclad layer, and the resulting overclad layer is cured to form the overclad 30. The method for applying the varnish-like composition is not particularly limited, but for example, a spin coating method can be used.

[0111] [Electronic equipment] The electronic device of this embodiment includes the optical waveguide of this embodiment, and preferably includes a silicon photonics device, and the silicon photonics device includes the optical waveguide of this embodiment. Here, silicon photonics refers to a technology for integrating elements such as optical waveguides, optical switches, optical modulators, and photodetectors on a silicon wafer, and silicon photonics devices refer to devices that utilize silicon photonics technology.

[0112] The silicon photonics device is, for example, a device in which an optical waveguide 100 is formed on a wafer 50, as shown in Fig. 1. In this case, the wafer 50 is a silicon wafer. The silicon photonics device may further include, for example, a Si wire waveguide.

[0113] Examples of the electronic device of this embodiment include electronic devices such as mobile phones, game consoles, router devices, WDM devices, personal computers, televisions, and home servers.

[0114] Although the embodiments of the present invention have been described above, these are merely examples of the present invention, and various other configurations can also be adopted. Furthermore, the present invention is not limited to the above-described embodiment, and modifications and improvements within the scope of achieving the object of the present invention are included in the present invention. [Example]

[0115] The present embodiment will be described in detail below based on examples and comparative examples, but the present embodiment is not limited to the descriptions of these examples.

[0116] [Raw materials] <Synthesis of Cyclic Olefin Resin (A-1)> Maleic anhydride (Nippon Shokubai Co., Ltd., 122.4 g, 1.25 mol), 2-norbornene (75 wt % toluene solution, Maruzen Petrochemical Co., Ltd., 156.8 g, 1.25 mol), and dimethyl 2,2'-azobis(2-methylpropionate) (V-601, Wako Pure Chemical Industries, Ltd., 11.5 g, 50 mmol) were weighed into an appropriately sized reaction vessel equipped with a stirrer and a condenser, and dissolved in methyl ethyl ketone (MEK, 150.8 g) and toluene (38.5 g). The solution was aerated with nitrogen for 10 minutes to remove oxygen, and then heated with stirring to 60° C. After 16 hours, MEK (320 g) was added to dilute the solution, and the solution was cooled. The reaction mixture was added dropwise to a large amount of methanol to precipitate the polymer. After filtering using a funnel, the polymer was washed with methanol and the solid was collected by filtration. The resulting polymer (hereinafter referred to as "precursor polymer") was vacuum dried at 70°C. The yield of the precursor polymer was 208.1 g, with a weight-average molecular weight (Mw) of 11,100 and a polydispersity (Mw / Mn) of 2.25. Next, the precursor polymer (10.0 g) was weighed and dissolved in MEK (30.0 g) in a suitable reaction vessel equipped with a stirrer and a condenser, followed by the addition of 2-hydroxyethyl methacrylate (HEMA, Nippon Shokubai Co., Ltd., 8.5 g, 65 mmol) and sodium acetate (1.0 g), and the mixture was heated at 70°C for 8 hours. To this reaction solution, glycidyl methacrylate (GMA, 3.7 g, 26 mmol) was added, and the mixture was further stirred at 70°C for 16 hours. After the reaction solution was treated with formic acid, it was added dropwise to a large amount of pure water to precipitate a polymer. The solid collected by filtration was dried in a vacuum dryer at 40°C for 16 hours, yielding 13.8 g of a pale yellow solid, cyclic olefin resin (A-1). The properties of cyclic olefin resin (A-1) were as follows: ·Weight average molecular weight (Mw): 16,200 ·Degree of dispersion: 2.46

[0117] <Synthesis of Cyclic Olefin Resin (A-2)> Maleic anhydride (MA, 122.4 g, 1.25 mol), 2-norbornene (NB, 117.6 g, 1.25 mol), and dimethyl 2,2'-azobis(2-methylpropionate) (11.5 g, 50.0 mmol) were weighed into a suitable reaction vessel equipped with a stirrer and condenser and dissolved in methyl ethyl ketone (MEK, 150.8 g) and toluene (77.7 g). The solution was purged with nitrogen for 10 minutes to remove oxygen and then heated to 60°C with stirring for 16 hours. MEK (320 g) was then added to a suspension of sodium hydroxide (12.5 g, 0.31 mol), 2-hydroxyethyl methacrylate (812.5 g, 6.25 mol), and toluene (480 g) and mixed at 45°C for 3 hours. The mixture was then cooled to 40°C and treated with formic acid (88% by weight aqueous solution, 49.0 g, 0.94 mol) to add protons. MEK and water were then added, and the aqueous layer was separated to remove inorganic residues. Methanol and hexane were then added, and the organic layer was separated to remove unreacted monomers. PGMEA was then added, and the methanol and 2-hydroxyethyl methacrylate in the system were distilled off under reduced pressure until the remaining amount was less than 1%. This yielded 1,050.0 g of a 20% by weight polymer solution (GPC Mw = 17,800, Mw / Mn = 2.43). The resulting polymer was designated cyclic olefin resin (A-2).

[0118] Details of the raw materials for each component in Table 1 are as follows:

[0119] <Cyclic olefin resin (A)> (A-1) Cyclic olefin resin synthesized above (A-2) Cyclic olefin resin synthesized above

[0120] <Polyfunctional (meth)acrylate (B)> (B-1) NK Ester A-DPH-SVF (manufactured by Shin-Nakamura Chemical Co., Ltd., a mixture of compounds having 5 to 6 acryloyl groups) (B-2) NK Ester 9G (manufactured by Shin-Nakamura Chemical Co., Ltd., a compound having two acryloyl groups)

[0121] <Polymerization initiator (C)> (C-1) Irugacure OXE01 (BASF, oxime ester type photoradical generator)

[0122] <Organic solvent (D)> (D-1) Propylene glycol monomethyl ether acetate (PGMEA)

[0123] <Adhesion aid> (E-1) X-12-967C (Shin-Etsu Chemical Co., Ltd., 3-trimethoxysilylpropylsuccinic anhydride, a silane coupling agent having a cyclic anhydride structure)

[0124] <Surfactant> (F-1)R-41 (manufactured by DIC Corporation, oligomer containing fluorine-containing group and lipophilic group)

[0125] [Examples 1 to 3] The raw materials formulated according to Table 1 were stirred at room temperature until the raw materials were completely dissolved, yielding a solution. The solution was then filtered through a filter with a pore size of 0.2 μm to obtain varnish-like clad compositions of Examples 1 to 3. In Table 1, the parts by mass of the cyclic olefin resin (A-2) are parts by mass of the solid content. The parts by mass of the organic solvent PGMEA are parts by mass including the PGMEA contained in the solution of cyclic olefin resin (A-2). Hereinafter, the compositions of Examples 1 to 3 may also be referred to as compositions A to C, respectively.

[0126] Examples and comparative examples of optical waveguides will be described below. First, the production of compositions D and E, which are raw materials for the optical waveguides, will be described.

[0127] <Production of Composition D> (Synthesis of polyimide resin 1) A 3-L glass separable flask equipped with a stirrer and a stirring blade was charged with 64.1 g (0.20 mol) of 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl (TFMB), 97.7 g (0.22 mol) of 4,4'-(hexafluoroisopropylidene)diphthalic dianhydride (6FDA), and 500 g of dimethylacetamide (DMAc). The mixture was stirred to dissolve TFMB and 6FDA in the DMAc. The mixture was then stirred under a nitrogen stream at room temperature for 12 hours to polymerize the mixture, yielding a polyamic acid solution.

[0128] After adding 16 g of pyridine to the obtained polyamic acid solution, 82 g of acetic anhydride was added dropwise at room temperature, and then the liquid temperature was kept at 20 to 100°C and stirring was continued for 24 hours to carry out the imidization reaction, thereby obtaining a polyimide solution.

[0129] The resulting polyimide solution was poured into 1,000 g of methanol in a 5 L container while stirring to precipitate a polyimide resin. The solid polyimide resin was then filtered using a suction filter and washed with 1,000 g of methanol. The solid was then dried at 100°C for 24 hours using a vacuum dryer, and then further dried at 200°C for 3 hours. This resulted in the production of polyimide resin 1, a polyimide powder having terminal acid anhydride groups. The weight average molecular weight (Mw) of Polyimide Resin 1 measured by GPC was 25,000. In addition, polyimide resin 1 1 H-NMR was measured, and the imidization rate was calculated from the quantitative value of the amide peak relative to the peak of the aromatic ring of the polyimide. The imidization rate was 99% or more.

[0130] (Synthesis of Tetraphenylphosphonium 4,4'-sulfonyldiphenolate) Into a separable flask equipped with a stirring device, 37.5 g (0.15 mol) of 4,4'-bisphenol S and 100 mL of methanol were charged, stirred and dissolved at room temperature. While further stirring, a solution prepared by dissolving 4.0 g (0.1 mol) of sodium hydroxide in 50 mL of methanol in advance was added. Subsequently, a solution prepared by dissolving 41.9 g (0.1 mol) of tetraphenylphosphonium bromide in 150 mL of methanol in advance was added. Stirring was continued for a while, and after adding 300 mL of methanol, the solution in the flask was added dropwise to a large amount of water while stirring to obtain a white precipitate. The precipitate was filtered and dried. Thus, white crystalline tetraphenylphosphonium 4,4'-sulfonyldiphenolate was obtained.

[0131] (Preparation of Composition D) 100 parts by mass of the above polyimide resin 1, 60 parts by mass of Biscoat #802 (manufactured by Osaka Organic Chemical Industry Co., Ltd., a mixture of polyfunctional acrylates, a compound having 5 to 10 acryloyl groups), 20 parts by mass of NK Ester A-9550 (manufactured by Shin-Nakamura Chemical Co., Ltd., a mixture of polyfunctional acrylates, a compound having 5 to 6 acryloyl groups), 20 parts by mass of Biscoat #300 (manufactured by Osaka Organic Chemical Industry Co., Ltd., a mixture of polyfunctional acrylates, a compound having 3 to 4 acryloyl groups), 10 parts by mass of Irugacure OXE01 (manufactured by BASF, an oxime ester type photo radical generator), 10 parts by mass of Perkadox BC (manufactured by Kayaku Nouryon Co., Ltd., an organic peroxide, cumyl peroxide), 7 parts by mass of TECHMORE VG3101L (manufactured by Printec Co., Ltd., an epoxy compound), 3 parts by mass of Celloxide 2021P (manufactured by Daicel Corporation, an epoxy compound), 3 parts by mass of the tetraphenylphosphonium·4,4'-sulfonyldiphenolate synthesized above, 5 parts by mass of KBM-503 (manufactured by Shin-Etsu Chemical Co., Ltd., 3-methacryloxypropyltrimethoxysilane), 2 parts by mass of X-12-967C (manufactured by Shin-Etsu Chemical Co., Ltd., 3-trimethoxysilylpropylsuccinic anhydride), 0.1 part by mass of FC4432 (manufactured by 3M, a fluorine-based surfactant), and 2 parts by mass of distilled water were dissolved in 282 parts by mass of ethyl acetate and 282 parts by mass of γ-butyrolactone, and stirred at room temperature until the raw materials were completely dissolved to obtain a solution. Then, the solution was filtered through a nylon filter with a pore size of 0.2 μm to obtain a varnish-like composition D.

[0132] <Production of Composition E> 26.0 parts by mass of an epoxy resin (manufactured by Nippon Kayaku Co., Ltd., product name: EPPN 201, polyfunctional epoxy resin, phenol novolac type epoxy resin), 7.8 parts by mass of a phenoxy resin (manufactured by Mitsubishi Chemical Corporation, product name: jER 1256, bisphenol A type phenoxy resin), 0.8 parts by mass of a photoacid generator (manufactured by San-Apro Ltd., product name: CPI-310B, onium salt compound), 0.1 parts by mass of a surfactant (manufactured by DIC Corporation, product name: R-41, fluorine-containing group and lipophilic group-containing oligomer), and 0.3 parts by mass of a silane coupling agent (manufactured by Shin-Etsu Chemical Co., Ltd., product name: X-12-967C) were dissolved in 65.0 parts by mass of propylene glycol monomethyl ether acetate and mixed at room temperature for 2.5 hours to obtain a mixed solution. Subsequently, pure water was added to the mixed solution so that the water content in 100% by mass of the composition was 7300 ppm, and the mixture was mixed again. The mixed solution was filtered through a 0.2 μm polypropylene filter to obtain a varnish-like composition E.

[0133] [Examples 4 to 6] [Manufacture of optical waveguide] (Formation of underclad) The liquid coatings obtained by spin-coating the underclad compositions described in Table 2 on an 8-inch silicon wafer were heated at 110°C for 4 minutes to dry, and underclad layers with a thickness of 10 μm were formed respectively. Subsequently, with respect to the obtained underclad layer, using an automatic exposure machine, i-line with a wavelength of 365 nm was exposed over the entire surface at an exposure dose of 130 mJ / cm 2 , heated on a hot plate at 120°C for 2 minutes in the air, and the silicon wafer was heated at 200°C for 120 minutes in a nitrogen atmosphere to form underclads respectively.

[0134] (Formation of core) The liquid coatings obtained by spin-coating composition D on the underclad were heated at 110°C for 3 minutes to dry, and core layers with a thickness of 7 μm were formed respectively. Subsequently, with respect to the obtained core layer, using an automatic exposure machine, i-line with a wavelength of 365 nm was exposed at 1300 mJ / cm 2The film was exposed to an exposure dose of 10 μm, and developed with cyclopentanone and PGMEA using a spray developer. The film was then heated on a hot plate in the atmosphere at 120°C for 2 minutes, and the silicon wafer was then heated in a nitrogen atmosphere at 170°C for 120 minutes to form a core with a line width of 10 μm.

[0135] (Overclad formation) The clad composition listed in Table 2 was spin-coated onto the core, and the resulting liquid coating was heated at 110°C for 4 minutes and dried to form an overclad layer 17 μm thick from the underclad surface (10 μm thick from the core surface). Subsequently, the obtained overcladding layer was exposed to i-line light of 365 nm wavelength at 130 mJ / cm using an automatic exposure machine. 2 The entire surface was exposed to an exposure amount of 1000 ppm, and the wafer was heated on a hot plate in the atmosphere at 120° C. for 2 minutes. The silicon wafer was then heated in a nitrogen atmosphere at 200° C. for 120 minutes to form an overclad, thereby obtaining the optical waveguides of Examples 4 to 6, respectively.

[0136] [Examples 7 to 9] <Optical waveguide manufacturing> (Underclad formation) The undercladding was formed in the same manner as in Examples 4 to 6.

[0137] (Core formation) Composition E was spin-coated onto the undercladding, and the resulting liquid film was dried by heating at 100° C. for 3 minutes to form a core layer having a thickness of 7 μm. Next, the obtained core layer was exposed to i-line light of 365 nm wavelength at 600 mJ / cm using an automatic exposure machine. 2 The silicon wafer was then heated on a hot plate in the atmosphere at 70° C. for 5 minutes, and then heated in a nitrogen atmosphere at 170° C. for 180 minutes to form cores with a line width of 10 μm.

[0138] (Overclad formation) Overclads were each formed in the same manner as in Examples 4 to 6 to obtain the optical waveguides of Examples 7 to 9, respectively.

[0139] [Comparative Example 1] [Manufacture of Optical Waveguide] (Formation of Underclad) A liquid film obtained by spin-coating Composition D on an 8-inch silicon wafer was heated at 110°C for 3 minutes to dry it, forming an underclad layer with a thickness of 10 μm. Subsequently, with respect to the obtained underclad layer, using an automatic exposure machine, i-line light with a wavelength of 365 nm was used to perform full-surface exposure at an exposure dose of 1300 mJ / cm 2 , heated on a hot plate in the atmosphere at 120°C for 2 minutes, and the silicon wafer was heated in a nitrogen atmosphere at 170°C for 120 minutes to form an underclad.

[0140] (Formation of Core) A core was formed in the same manner as in Examples 7 to 9.

[0141] (Formation of Overclad) A liquid film obtained by spin-coating Composition D on the core was heated at 110°C for 3 minutes to dry it, forming an overclad layer with a thickness of 17 μm from the underclad surface (10 μm from the core surface). Subsequently, with respect to the obtained overclad layer, using an automatic exposure machine, i-line light with a wavelength of 365 nm was used to perform full-surface exposure at an exposure dose of 1300 mJ / cm 2 , heated on a hot plate in the atmosphere at 120°C for 2 minutes, and the silicon wafer was heated in a nitrogen atmosphere at 170°C for 120 minutes to form an overclad, obtaining the optical waveguide of Comparative Example 1.

[0142] [Measurement and Evaluation] [Measurement of Refractive Index of Composition] For the clad compositions of Examples 1 to 3, the refractive index was measured using a prism coupler (manufactured by Metricon) based on the following conditions. The refractive index at 30 °C and a wavelength of 1310 nm was calculated using the Cauchy dispersion formula from the refractive index values at three wavelengths of the following measurement wavelengths. The refractive indices at 30 °C and a wavelength of 1310 nm for each example are shown in Table 1 respectively. Substrate: Si wafer Film thickness: 5 μm Measurement temperature: 30 °C Measurement wavelengths: 404 nm, 633 nm, 832 nm

[0143] <Measurement of absorbance of the composition> For the clad compositions of Examples 1 to 3, the absorbance at 22 °C and a wavelength of 1310 nm was measured based on the following conditions. The absorbance of the composition was defined as the value obtained by dividing the measured value by the concentration of the measurement sample. Measuring device: Spectrophotometer (manufactured by JASCO Corporation, product name: V-670 EX) Test method: Measurement of parallel light transmittance Measurement temperature: 22 °C Measurement wavelength: 1310 nm Measurement sample: DMSO solution of the composition Concentration of the measurement sample: 10%

[0144] <Evaluation of propagation loss of the optical waveguide> (Environmental test) An environmental test was conducted by heating the optical waveguides fabricated on the silicon wafers of Examples 4 to 9 and Comparative Example 1 in an oven at 125 °C for 1000 hours, and the optical waveguides after the environmental test were obtained respectively.

[0145] (Propagation loss evaluation) For the optical waveguides before and after the environmental test, the propagation loss was measured respectively by the cut-back method. Specifically, a laser beam with a wavelength of 1310 nm was incident on the core part of the test piece through a single-mode optical fiber. Next, the intensity of the light emitted from the core part of the test piece was acquired while changing the length of the test piece, and the propagation loss per unit length of the optical waveguide was calculated. The propagation loss of the optical waveguide was evaluated based on the following evaluation criteria. The evaluation results for each example and comparative example are shown in Table 2. A: The difference between the propagation loss of the optical waveguide after the environmental test and the propagation loss of the optical waveguide before the environmental test is less than 0.15 dB / cm B: The difference between the propagation loss of the optical waveguide after the environmental test and the propagation loss of the optical waveguide before the environmental test is 0.15 dB / cm or more and less than 0.40 dB / cm C: The difference between the propagation loss of the optical waveguide after the environmental test and the propagation loss of the optical waveguide before the environmental test is 0.40 dB / cm or more

[0146] [Table 1]

[0147] [Table 2]

[0148] As can be seen from Table 2, the optical waveguides of the Examples all had better propagation loss evaluation results than the optical waveguides of the Comparative Examples. That is, it can be seen that the cladding composition of this embodiment makes it possible to obtain an optical waveguide with improved thermal reliability. [Explanation of symbols]

[0149] 10 Underclad 20 cores 30 Overclad 50 wafers 100 optical waveguide

Claims

1. A composition for a cladding that can be used for the cladding of an optical waveguide, comprising a cyclic olefin resin (A) and a polyfunctional (meth)acrylate (B).

2. The cyclic olefin resin (A) contains a structural unit represented by the following formula (1) and a structural unit represented by the following formula (2). The composition for a cladding according to Claim 1. 【Chemical 1】 (In the above formula (1), R １ , R ２ , R ３ and R ４ are each independently a hydrogen atom or an organic group having 1 to 30 carbon atoms, and a １ is 0, 1 or 2) [Chemical Formula 2] (In the above formula (2), R １１ is a group containing a terminal reactive unsaturated double bond, and R ２１ is a hydrogen atom or an organic group having 1 to 3 carbon atoms).

3. The cyclic olefin resin (A) further contains a structural unit represented by the following formula (3). The composition for a cladding according to Claim 2. 【Chemical Formula 3】 (In the above formula (3), R ２２ is a hydrogen atom or an organic group having 1 to 3 carbon atoms)

4. The cyclic olefin resin (A) further contains a structural unit represented by the following formula (4). The composition for a cladding according to Claim 2 or 3. 【Chemical Formula 4】 (In the above formula (4), R ２１ and R ２２ are each independently a hydrogen atom or an organic group having 1 to 3 carbon atoms)

5. When the content of the cyclic olefin resin (A) in the composition for a cladding is 50% by mass or more based on 100% by mass of the total solid content in the composition for a cladding. The composition for a cladding according to Claim 1 or 2.

6. The polyfunctional (meth)acrylate (B) contains a (meth)acrylate compound (B1) having 5 or more functional groups. The composition for a cladding according to Claim 1 or 2.

7. The polyfunctional (meth)acrylate (B) contains a (meth)acrylate compound (B2) having 2 or more and 4 or less functional groups. The composition for a cladding according to Claim 1 or 2.

8. The composition for a cladding according to Claim 1 or 2 further contains a polymerization initiator (C).

9. The polymerization initiator (C) in the composition for a cladding according to Claim 8 contains a photo radical polymerization initiator.

10. The composition for a cladding according to Claim 1 or 2 further contains an organic solvent (D).

11. The composition for a cladding according to Claim 1 or 2 is in the form of a varnish.

12. The composition for a cladding according to Claim 1 or 2 has a refractive index of 1.470 or more and 1.530 or less at 30 °C and a wavelength of 1310 nm.

13. The composition for a cladding according to Claim 1 or 2 has an absorbance of 0.030 or more and 0.070 or less at 22 °C and a wavelength of 1310 nm.

14. A composition set comprising the composition for a cladding according to Claim 1 or 2 and a composition for a core that can be used for the core of an optical waveguide.

15. The composition set according to Claim 14, wherein the composition for a core contains a polyimide resin and a polyfunctional (meth)acrylate.

16. The composition set according to claim 14, wherein the composition for the core contains an epoxy resin and a phenoxy resin.

17. An optical waveguide comprising a clad made of the composition for the clad according to claim 1 or 2.

18. Comprising a silicon photonics device, The silicon photonics device is an electronic device comprising the optical waveguide according to claim 17.

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