Resin composition, resin film, film, film set, optical waveguide, optoelectronic composite substrate, and electronic component

Abstract

A resin composition that can be used for an optical waveguide cladding, comprising a cyclic olefin resin (A), wherein the cyclic olefin resin (A) contains a structural unit (a) and a structural unit (b), the structural unit (a) is a structural unit represented by formula (a-1), and the structural unit (b) is one or more selected from the group consisting of a structural unit represented by formula (b-1), a structural unit represented by formula (b-2), and a structural unit represented by formula (b-3).

Description

Technical Field

[0001] The present invention relates to a resin composition, a resin film, a film, a film set, an optical waveguide, an optoelectronic composite substrate, and an electronic component.

Background Art

[0002] In recent years, in information and 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, an optoelectronic composite substrate has been studied.

[0003] The optoelectronic composite substrate includes, for example, a substrate on which an optical waveguide is provided. Examples of the technology related to the optoelectronic composite substrate include the technologies described in Patent Documents 1 and 2.

[0004] Patent Document 1 describes an optoelectronic hybrid substrate including a flexible circuit board having electrical wiring with mounting pads formed on the surface of an insulating layer, an element mounted on the mounting pads, and an optical waveguide laminated on the back side of the insulating layer. The flexible circuit board is a flexible double-sided circuit board having electrical wiring formed on the back surface of the insulating layer. A metal reinforcing layer is formed by plating on at least a portion corresponding to the mounting pads among the electrical wiring on the back side, and the optical waveguide is in contact with the metal reinforcing layer. According to the optoelectronic hybrid substrate described in Patent Document 1, a metal reinforcing layer is adhered to the insulating layer of the flexible circuit board without an adhesive layer, and the metal reinforcing layer suppresses deformation due to the pressing load during element mounting, so that an optoelectronic hybrid substrate in which the element is properly mounted can be provided.

[0005] Patent Document 1 describes preparing a substrate in which copper foils 21 are formed on the front and back surfaces of an insulating layer 1 made of a resin such as polyimide, and forming a through-hole 1a for an optical path and via holes 1b in the substrate (see paragraph 0023 of Patent Document 1). And a flexible double-sided circuit board E on which a metal reinforcing layer M is formed is described (see paragraph 0028 of Patent Document 1). The flexible double-sided circuit board E includes the above substrate. Furthermore, Patent Document 1 describes forming an underclad layer 6 in a state of being in contact with a metal reinforcing layer M that covers the back-side electrical wiring 2B on the back side of the flexible double-sided circuit board E, and as a molding material for the underclad layer 6, for example, photosensitive resin, thermosetting resin, etc. are mentioned (see paragraph 0029 of Patent Document 1). According to FIGS. 4 to 6 of Patent Document 1, it can be understood that the molding material of the underclad layer 6 is filled in the recesses formed in the flexible double-sided circuit board E on which the metal reinforcing layer M is formed.

[0006] Patent Document 2 discloses an optoelectronic wiring board in which a rigid portion in which a conductor circuit and an insulating layer are laminated on both sides of a substrate and one or more bendable flex portions are integrated. In the rigid portion, external connection terminals for mounting an optical element and / or a package substrate on which an optical element is mounted are formed, and an optoelectronic wiring board characterized in that optical wiring is formed in at least one of the flex portions is described. According to the optoelectronic wiring board of Patent Document 2, it is described that high-capacity information processing and high-speed information processing can be suitably performed without increasing the size of the wiring board.

[0007] The rigid portion described in Patent Document 2 has an optical signal passing region formed therein, and it is described that the optical signal passing region is filled with a resin composition therein (see Claims 4 and 5 of Patent Document 2). Furthermore, it is described that the optical signal passing region is formed so as to penetrate all the substrates and insulating layers constituting the rigid portion (see Claim 6 of Patent Document 2).

[0008] Furthermore, Patent Document 2 describes a substrate 221 composed of an optical waveguide film 250 and a resin layer (insulating layer) 221a around it, and it is described that the resin layer 221a constitutes a part of the optical signal passing regions 242a and 242b (see paragraph 0033 of Patent Document 2).

Prior Art Documents

Patent Documents

[0009]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0010] As described in Patent Documents 1 and 2, in the conventional technology related to optoelectronic composite substrates, an optoelectronic composite substrate in which a recess formed in the substrate and a via formed in the substrate are filled with a resin composition is known.

[0011] As a manufacturing process of an optoelectronic composite substrate, for example, a process of integrating a substrate with a via formed thereon and a film for an optical waveguide cladding can be mentioned. In this process, it is necessary to embed the via formed in the substrate with the optical waveguide cladding. That is, the resin composition that can be used for the optical waveguide cladding is required to have a property that enables the above resin composition to be sufficiently embedded in the via (hereinafter, "embeddability" means the property of how much the resin composition that can be used for the optical waveguide cladding can be embedded in the via).

[0012] In addition, the resin composition that can be used for the optical waveguide cladding is also required to have a high light transmittance.

[0013] The present invention has been made in view of the above circumstances, and provides a resin composition capable of improving embeddability while suppressing a decrease in light transmittance.

Means for Solving the Problem

[0014] According to the present invention, there are provided the following resin compositions, resin films, films, film sets, optical waveguides, optoelectronic composite substrates, and electronic components.

[0015] [1] A resin composition that can be used for an optical waveguide cladding, comprising a cyclic olefin resin (A), wherein the cyclic olefin resin (A) includes a structural unit (a) and a structural unit (b), the structural unit (a) is a structural unit represented by the following formula (a-1), and the structural unit (b) is one or more selected from the group consisting of a structural unit represented by the following formula (b-1), a structural unit represented by the following formula (b-2), and a structural unit represented by the following formula (b-3).

Chemical formula

Chemical formula

Chemical formula

Chemical formula

[10] The refractive index of the compound (B) having a cyclic ether structure is 1.45 or more and 1.55 or less. The resin composition according to any one of [5] to [9] above.

[11] The content of the compound (B) having a cyclic ether structure in the resin composition is 20 parts by mass or more and 80 parts by mass or less when the total content of the resin components in the resin composition is 100 parts by mass. The resin composition according to any one of [5] to

[10] .

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

[11] , further comprising a curing agent (C).

[13] The resin composition according to

[12] , wherein the curing agent (C) contains a cationic polymerization initiator.

[14] The resin composition according to

[13] , wherein the cationic polymerization initiator contains a photo cationic polymerization initiator.

[15] The resin composition according to

[13] or

[14] , wherein the cationic polymerization initiator contains a thermal cationic polymerization initiator.

[16] The resin composition according to any one of

[12] to

[15] , wherein the curing agent (C) contains an imidazole-based compound.

[17] The content of the curing agent (C) contained in the resin composition is 0.05 parts by mass or more and 10.0 parts by mass or less when the total content of the resin components in the resin composition is 100 parts by mass. The resin composition according to any one of

[12] to

[16] .

[18] The refractive index of the resin composition is 1.47 or more and 1.55 or less. The resin composition according to any one of [1] to

[17] .

[19] A resin film comprising the resin composition according to any one of [1] to

[18] , The resin film has a light transmittance of 85% or more at a wavelength of 850 nm. The resin film.

[20] The resin film has a thickness of 1 μm or more and 150 μm or less. The resin film according to

[19] .

[21] A film that can be used for an optical waveguide cladding, The film includes a resin layer formed of the resin composition according to any one of [1] to

[18] .

[22] Furthermore, it includes a base film, The film according to

[21] , which has the resin layer on the base film.

[23] The film according to

[22] , wherein the resin constituting the base film contains at least one or two or more selected from the group consisting of polyimide and polyethylene terephthalate.

[24] The film according to any one of

[21] to

[23] , wherein the film is a dry film.

[25] A film set that can be used for an optical waveguide clad, Including a first film and a second film, The film set, wherein at least one of the first film and the second film is the film according to any one of

[21] to

[24] .

[26] An optical waveguide in which a first clad layer, a core layer, and a second clad layer are laminated in this order, The optical waveguide, wherein at least one of the first clad layer and the second clad layer contains the resin composition according to any one of [1] to

[18] .

[27] A substrate, An optoelectronic composite substrate including the optical waveguide according to

[26] provided on the substrate.

[28] An electronic component including the optoelectronic composite substrate according to

[27] .

Advantages of the Invention

[0016] According to the present invention, it is possible to provide a resin composition capable of improving the embedding property while suppressing a decrease in light transmittance.

Brief Description of the Drawings

[0017]

Figure 1

Best Mode for Carrying Out the Invention

[0018] 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.

[0019] FIG. 1 is a cross-sectional view schematically showing an example of the structure of the optoelectronic composite substrate of the present embodiment. As shown in FIG. 1, an optical waveguide 100 is provided on a substrate 110 in the optoelectronic composite substrate 200. In the optical waveguide 100, a first cladding layer 20, a core layer 30, and a second cladding layer 40 are laminated in this order. A mirror 50 on the light-emitting element side and a mirror 60 on the light-receiving element side are formed in the optical waveguide 100. Vias 140 (140a, 140b) are formed in the substrate 110 (note that the via 140 shown in FIG. 1 is in a state of being embedded by the first cladding layer 20). A light-emitting element 120 and a light-receiving element 130 are provided on the side of the substrate 110 opposite to the optical waveguide 100 side.

[0020] The light propagation path in the optoelectronic composite substrate 200 will be specifically described with reference to FIG. 1. The light emitted from the light-emitting portion of the light-emitting element 120 passes through the via 140a formed in the substrate 110, enters the mirror 50 on the light-emitting element side, is transmitted through the core layer 30, then enters the mirror 60 on the light-receiving element side, passes through the via 140b formed in the substrate 110, and enters the light-receiving element 130. Note that the arrows in FIG. 1 schematically show the light propagation.

[0021] When providing the optical waveguide 100 on the substrate 110, for example, it includes a step of laminating the substrate 110 on which the via 140 is formed and a film for forming the first cladding layer 20 and integrating them by heating and pressurization. In the integration step, it is necessary to embed the via 140 with the first cladding layer 20.

[0022] According to the study by the present inventors, in the conventional materials for forming an optical waveguide clad, the optical waveguide clad cannot be sufficiently embedded in the vias formed in the substrate, and dents may occur on the surface of the optical waveguide clad opposite to the substrate side (i.e., the core layer side of the optical waveguide clad), or voids may occur in the vias. And it has been found that when the above-mentioned dents and voids occur in the optoelectronic composite substrate, optical loss occurs at the interfaces of the dents and voids. That is, the resin composition that can be used for the optical waveguide clad is required to have a property that enables the above resin composition to be sufficiently embedded in the vias.

[0023] Also, as described above, the first clad layer 20 embedded in the via 140 serves as a light propagation path. Therefore, the resin composition that can be used for the optical waveguide clad is also required to have a high light transmittance (for example, the light transmittance at a wavelength of 850 nm).

[0024] The present invention has been made in view of the above circumstances, and provides a resin composition capable of improving the embedding property while suppressing a decrease in light transmittance.

[0025] Furthermore, according to the present invention, an optoelectronic composite substrate capable of suppressing propagation loss can be provided.

[0026] [Resin Composition] The resin composition of the present embodiment is a resin composition that can be used for an optical waveguide clad, includes a cyclic olefin resin (A), and the cyclic olefin resin (A) includes a structural unit (a) and a structural unit (b). The structural unit (a) is a structural unit represented by the formula (a-1), and the structural unit (b) is one or more selected from the group consisting of a structural unit represented by the formula (b-1), a structural unit represented by the formula (b-2), and a structural unit represented by the formula (b-3).

[0027] [Chemical Formula]

[0028] In formula (a-1), R 1 , R 2 , R 3 and R 4 each independently represents a hydrogen atom, a hydroxyl group, or an organic group having 1 to 30 carbon atoms.

[0029]

Chemical formula

[0030] In formula (b-1), R 11 represents a hydrogen atom, a hydroxyl group, or an organic group having 1 to 30 carbon atoms.

[0031]

Chemical formula

[0032]

Chemical formula

[0033] In formula (b-3), R 21 and R 22 each independently represents a hydrogen atom or an organic group having 1 to 30 carbon atoms.

[0034] From the viewpoint of further improving the light propagation efficiency of the optical waveguide, the refractive index of the resin composition of the present embodiment is preferably 1.55 or less, more preferably 1.54 or less, still more preferably 1.53 or less, and even more preferably 1.52 or less. The lower limit is not particularly limited, but may be, for example, 1.47 or more, or 1.48 or more. The refractive index of the resin composition means the refractive index measured under the conditions of 23°C and 589 nm using an Abbe refractometer for the resin film composed of the resin composition. The resin film composed of the resin composition can be produced, for example, by applying and drying the resin composition on a base film as in the method described in the examples.

[0035] The light transmittance of the resin composition of the present embodiment at a wavelength of 850 nm is preferably 85% or more, more preferably 90% or more, still more preferably 95% or more, still more preferably 97% or more, and still more preferably 98% or more from the viewpoint of further improving the light propagation efficiency of the optical waveguide. The light transmittance of the resin composition at a wavelength of 850 nm means the value of the light transmittance measured by an ultraviolet-visible spectrophotometer for a resin film made of a resin composition with a thickness of 25 μm. The resin film made of a resin composition with a thickness of 25 μm can be produced, for example, by applying and drying the resin composition on a base film as described in the method of the examples.

[0036] The shape of the resin composition of the present embodiment is not particularly limited, and examples thereof include shapes such as film shape, sheet shape, varnish shape, and sheet shape.

[0037] Hereinafter, each constituent component of the resin composition of the present embodiment will be described.

[0038] <Cyclic olefin resin (A)> The resin composition of the present embodiment contains a cyclic olefin resin (A). The cyclic olefin resin (A) contains a structural unit (a) and a structural unit (b).

[0039] In the cyclic olefin resin (A), the structural unit (a) is a structural unit represented by the formula (a-1).

[0040]

Chemical formula

[0041] In the formula (a-1), R 1 , R 2 , R 3 and R 4 each independently represent a hydrogen atom, a hydroxyl group, or an organic group having 1 to 30 carbon atoms. In formula (a-1), the organic group having 1 to 30 carbon atoms is preferably an organic group having 1 to 25 carbon atoms, more preferably an organic group having 1 to 20 carbon atoms, and still more preferably an organic group having 1 to 15 carbon atoms.

[0042] In formula (a-1), R 1 , R 2 , R 3 and R 4 As the organic groups constituting them, for example, at least one selected from the group consisting of 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 organic group having a carboxyl group, and an organic group having a heterocycle can be mentioned. 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, a decyl group, and a dodecyl group. 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. Examples of the alkynyl group include an ethynyl group. Examples of the alkylidene group include at least one selected from the group consisting of a methylidene group and an ethylidene group. Examples of the aryl group include at least one selected from the group consisting of a phenyl group, a naphthyl group, and an anthracenyl group. Examples of the aralkyl group include at least one selected from the group consisting of a benzyl group and a phenethyl group. Examples of the alkaryl group include at least one selected from the group consisting of a tolyl group and a xylyl group. 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. Examples of the organic group having a heterocyclic ring include an organic group having an epoxy group and an oxetanyl group.

[0043] R 1 、R 2 、R 3 and R 4 In the organic groups constituting, the alkyl group, alkenyl group, alkynyl group, alkylidene group, aryl group, aralkyl group, alkaryl group, cycloalkyl group, organic group having a carboxyl group, and organic group having a heterocyclic ring may have one or more hydrogen atoms substituted by a halogen atom. Examples of the halogen atom include fluorine, chlorine, bromine, and iodine.

[0044] From the viewpoint of further improving the film-forming property of the resin composition, at least one selected from the group consisting of R 1 、R 2 、R 3 and R 4 is preferably an alkyl group. Also, from the viewpoint of further improving the heat resistance and strength of the cured product of the resin composition, at least one selected from the group consisting of R 1 、R 2 、R 3 and R 4 is preferably at least one selected from the group consisting of an organic group having a carboxyl group and an organic group having a heterocyclic ring.

[0045] Among these, in formula (a-1), R 1 、R 2 、R 3 and R 4Each independently preferably represents a hydrogen atom, an organic group having a carboxyl group, or an organic group having a heterocyclic ring, more preferably represents a hydrogen atom, an organic group having a carboxyl group, or an organic group having an epoxy group, still more preferably represents a hydrogen atom, an organic group having 1 to 8 carbon atoms and a carboxyl group, or an organic group having 1 to 8 carbon atoms and an epoxy group, and even more preferably represents a hydrogen atom, an organic group having 1 to 4 carbon atoms and a carboxyl group, or an organic group having 1 to 4 carbon atoms and an epoxy group.

[0046] In the cyclic olefin resin (A), the structural unit (b) is one or more selected from the group consisting of the structural unit represented by the formula (b-1), the structural unit represented by the formula (b-2), and the structural unit represented by the formula (b-3).

[0047] The structural unit represented by the formula (b-1) is shown below.

[0048]

Chemical formula

[0049] In the formula (b-1), R 11 represents a hydrogen atom, a hydroxyl group, or an organic group having 1 to 30 carbon atoms. In the formula (b-1), the organic group having 1 to 30 carbon atoms is preferably an organic group having 1 to 25 carbon atoms, more preferably an organic group having 1 to 20 carbon atoms, and still more preferably an organic group having 1 to 15 carbon atoms.

[0050] In the formula (b-1), R 11 Examples of the organic group constituting R R 11 Specific examples of the alkyl group, alkenyl group, alkynyl group, alkylidene group, aryl group, aralkyl group, alkaryl group, and cycloalkyl group as the organic group constituting R 1, R 2 , R 3 and R 4 are the same as the specific examples described for the organic groups that make them up.

[0051] R 11 In the organic group that makes up R 11 , one or more hydrogen atoms may be substituted by a halogen atom. Examples of the halogen atom include fluorine, chlorine, bromine, and iodine.

[0052] Among these, in formula (b-1), R 11 preferably represents a hydrogen atom, an alkyl group, or a cycloalkyl group, and R 11 more preferably represents a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, or a cycloalkyl group having 1 to 20 carbon atoms, and even more preferably represents a hydrogen atom, a dodecyl group, or a cyclohexyl group. 11 is preferably a hydrogen atom, an alkyl group or a cycloalkyl group, and R 11 11 more preferably represents a hydrogen atom, an alkyl group having 1 to 20 carbon atoms or a cycloalkyl group having 1 to 20 carbon atoms, and even more preferably represents a hydrogen atom, a dodecyl group or a cyclohexyl group.

[0053] The structural unit represented by formula (b-2) is shown below.

[0054]

Chemical formula

[0055] The structural unit represented by formula (b-3) is shown below.

[0056]

Chemical formula

[0057] In formula (b-3), R 21 21 and R 22 22 each independently represent a hydrogen atom or an organic group having 1 to 30 carbon atoms. In formula (b-3), the organic group having 1 to 30 carbon atoms is preferably an organic group having 1 to 25 carbon atoms, more preferably an organic group having 1 to 20 carbon atoms, and even more preferably an organic group having 1 to 15 carbon atoms.

[0058] In formula (b-3), R 21 21and R 22 Examples of the organic group constituting R 21 and R 22 include at least one selected from the group consisting of an alkyl group, an alkenyl group, an alkynyl group, an alkylidene group, an aryl group, an aralkyl group, an alkaryl group, a cycloalkyl group, a group having an acryloyl group, and a group having a methacryloyl group. 1 R 2 R 3 and R 4 are the same as the specific examples described for the organic group constituting

[0059] R 21 and R 22 In the organic group constituting

[0060] Among these, in formula (b-3), R 21 and R 22 each preferably independently represents a hydrogen atom or an alkyl group, and more preferably represents a hydrogen atom or an n-butyl group.

[0061] In formula (b-3), it is preferable that R 21 is a hydrogen atom and R 22 is an organic group having 1 to 30 carbon atoms. More preferably, R 21 is a hydrogen atom and R 22 is an alkyl group. Even more preferably, R 21 is a hydrogen atom and R 22 is an alkyl group having 1 to 10 carbon atoms. Even more preferably, R 21 is a hydrogen atom and R 22 is an n-butyl group.

[0062] The cyclic olefin resin (A) may contain a structural unit (a) and structural units other than the structural unit (b). Examples of the other structural units include structural units derived from compounds having an ethylenic double bond. Examples of the compound having an ethylenic double bond include α-olefins having 2 to 20 carbon atoms such as ethylene, propylene, 1-butene, 1-pentene, 1-hexene, 3-methyl-1-butene, 3-methyl-1-pentene, 3-ethyl-1-pentene, 4-methyl-1-pentene, 4-methyl-1-hexene, 4,4-dimethyl-1-hexene, 4,4-dimethyl-1-pentene, 4-ethyl-1-hexene, 3-ethyl-1-hexene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, 1-eicosene; non-conjugated dienes such as 1,4-hexadiene, 4-methyl-1,4-hexadiene, 5-methyl-1,4-hexadiene, 1,7-octadiene; acrylic acids such as acrylic acid, methacrylic acid, α-ethylacrylic acid, 2-hydroxyethyl (meth)acrylate; maleic acids such as maleic acid, maleic anhydride, dimethyl maleic acid, diethyl maleic acid, dibutyl maleic acid; vinyl ethers such as ethyloxetane vinyl ether, ethyl vinyl ether, cyclohexyl vinyl ether, allyl vinyl ether; and at least one selected from the group consisting of these.

[0063] When the total of all the structural units in the cyclic olefin resin (A) is 100 mol%, the content of the structural unit (a) in the cyclic olefin resin (A) is preferably 10 mol% or more, more preferably 15 mol% or more, still more preferably 30 mol% or more, still more preferably 35 mol% or more, still more preferably 40 mol% or more, and preferably 70 mol% or less, more preferably 65 mol% or less, still more preferably 60 mol% or less.

[0064] When the total of all structural units in the cyclic olefin resin (A) is 100 mol%, the content of the structural unit (b) in the cyclic olefin resin (A) is preferably 10 mol% or more, more preferably 20 mol% or more, still more preferably 30 mol% or more, still more preferably 35 mol% or more, still more preferably 40 mol% or more, and is preferably 70 mol% or less, more preferably 65 mol% or less, still more preferably 60 mol% or less.

[0065] When the total of all structural units in the cyclic olefin resin (A) is 100 mol%, the total content of the structural unit (a) and the structural unit (b) in the cyclic olefin resin (A) is preferably 50 mol% or more, more preferably 60 mol% or more, still more preferably 65 mol% or more, and is, for example, 100 mol% or less.

[0066] From the viewpoint of further improving the light propagation efficiency of the optical waveguide, the refractive index of the cyclic olefin resin (A) is preferably 1.55 or less, more preferably 1.53 or less, still more preferably 1.52 or less, and the lower limit is not particularly limited, and may be, for example, 1.45 or more or 1.48 or more. The refractive index of the cyclic olefin resin (A) means the refractive index under the conditions of 23 °C and 589 nm measured by an Abbe refractometer.

[0067] The weight average molecular weight (Mw) of the cyclic olefin resin (A) is preferably 4,000 or more, more preferably 5,000 or more, still more preferably 6,000 or more, and from the viewpoint of further improving the solubility in an organic solvent, it is preferably 20,000 or less, more preferably 18,000 or less, still more preferably 16,000 or less. The weight average molecular weight (Mw) of the cyclic olefin resin (A) can be determined by gel permeation chromatography (GPC) using polystyrene as a standard substance.

[0068] When the total content of the resin components of the resin composition is 100 parts by mass, the content of the cyclic olefin resin (A) in the resin composition of the present embodiment is preferably 20 parts by mass or more, more preferably 23 parts by mass or more, still more preferably 25 parts by mass or more, still more preferably 28 parts by mass or more from the viewpoint of suppressing a decrease in light transmittance and further improving the embeddability, and preferably 100 parts by mass or less, more preferably 80 parts by mass or less, more preferably 75 parts by mass or less, still more preferably 70 parts by mass or less, still more preferably 65 parts by mass or less from the viewpoint of suppressing a decrease in light transmittance and further improving the embeddability.

[0069] When the total content of all components of the resin composition is 100% by mass, the content of the cyclic olefin resin (A) in the resin composition of the present embodiment is preferably 5% by mass or more, more preferably 8% by mass or more, still more preferably 10% by mass or more, still more preferably 20% by mass or more, still more preferably 25% by mass or more, still more preferably 28% by mass or more from the viewpoint of suppressing a decrease in light transmittance and further improving the embeddability, and preferably less than 100% by mass, more preferably 80% by mass or less, more preferably 75% by mass or less, still more preferably 70% by mass or less, still more preferably 65% by mass or less from the viewpoint of suppressing a decrease in light transmittance and further improving the embeddability.

[0070] 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 any method. Here, examples of the monomer capable of forming the structural unit represented by the formula (a-1) include 2-norbornene, methyl glycidyl ether norbornene, 5-norbornene-2-carboxylic acid, and the like. Examples of the monomer capable of forming the structural unit represented by the formula (b-1) include maleimide, N-cyclohexyl maleimide, and the like. Examples of the monomer capable of forming the structural unit represented by the formula (b-2) include maleic anhydride. Examples of the monomer capable of forming the structural unit represented by the formula (b-3) include 1-butyl hydrogen maleate, ethyl hydrogen maleate, and the like.

[0071] 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.

[0072] <Compound (B) having a cyclic ether structure> From the viewpoint of further improving the embeddability, the resin composition of the present embodiment preferably further contains a compound (B) having a cyclic ether structure. Here, as the compound (B) having a cyclic ether structure in the present embodiment, monomers, oligomers, and polymers in general can be used, and the molecular weight and molecular structure thereof are not particularly limited. In addition, in this specification, the resin component in the resin composition is assumed to include the compound (B) having a cyclic ether structure.

[0073] The compound (B) having a cyclic ether structure preferably contains at least one or two or more selected from the group consisting of epoxy compounds and oxetane compounds.

[0074] The compound (B) having a cyclic ether structure preferably contains an alicyclic structure in the molecule. Here, that the compound (B) having a cyclic ether structure contains an alicyclic structure in the molecule means that it contains an alicyclic structure in addition to the cyclic ether structure. However, the alicyclic structure of the present embodiment includes a condensed ring structure in which a cyclic ether and an aliphatic ring are condensed, and a spiro ring structure in which a cyclic ether and an aliphatic ring are bonded by a spiro bond atom. The number of members of the ring in the alicyclic structure is not particularly limited, but is preferably 4 to 10 membered rings, more preferably 4 to 8 membered rings, still more preferably 5 or 6 membered rings, and still more preferably 6 membered rings.

[0075] The compound (B) having a cyclic ether structure preferably contains two or more cyclic ether structures in the molecule, and more preferably contains two or three cyclic ether structures in the molecule.

[0076] From the viewpoint of handleability in producing the resin composition, the compound (B) having a cyclic ether structure is preferably liquid at 23°C.

[0077] From the viewpoint of further improving the light propagation efficiency of the optical waveguide, the refractive index of the compound (B) having a cyclic ether structure is preferably 1.55 or less, more preferably 1.53 or less, still more preferably 1.52 or less, and the lower limit is not particularly limited. For example, it may be 1.45 or more or 1.48 or more. The refractive index of the compound (B) having a cyclic ether structure means the refractive index under the conditions of 23°C and 589 nm measured by an Abbe refractometer.

[0078] When the total content of the resin components in the resin composition is 100 parts by mass, the content of the compound (B) having a cyclic ether structure in the resin composition of the present embodiment is preferably 20 parts by mass or more, more preferably 25 parts by mass or more, still more preferably 30 parts by mass or more, still more preferably 35 parts by mass or more, and preferably 80 parts by mass or less, more preferably 75 parts by mass or less, from the viewpoint of further improving the embedding property.

[0079] The compound (B) having a cyclic ether structure may be a compound having one kind of cyclic ether structure or may contain a compound having two or more kinds of cyclic ether structures.

[0080] <Hardening agent (C)> The resin composition of the present embodiment preferably further contains a hardening agent (C). Examples of the hardening agent (C) include at least one selected from the group consisting of thermal polymerization initiators, photopolymerization initiators, amine compounds, and the like.

[0081] The curing agent (C) preferably contains a cationic polymerization initiator. Examples of the cationic polymerization initiator include photo cationic polymerization initiators, thermal cationic polymerization initiators, and the like.

[0082] The curing agent (C) contains a cationic polymerization initiator, and preferably contains a photo cationic polymerization initiator as the cationic polymerization initiator. The photo cationic polymerization initiator includes, for example, sulfonium salt type polymerization initiators, iodonium salt type polymerization initiators, etc., preferably contains a sulfonium salt type polymerization initiator, more preferably contains a triaryl sulfonium salt type polymerization initiator, and even more preferably contains a triphenyl sulfonium salt type polymerization initiator.

[0083] The curing agent (C) contains a cationic polymerization initiator, and preferably contains a thermal cationic polymerization initiator as the cationic polymerization initiator. The thermal cationic polymerization initiator includes, for example, sulfonium salt type polymerization initiators, iodonium salt type polymerization initiators, etc., and preferably contains a sulfonium salt type polymerization initiator.

[0084] The curing agent (C) preferably contains an imidazole-based compound. The imidazole-based compound means a compound containing an imidazole ring structure, for example, a compound in which the hydrogen of imidazole is substituted with a hydrocarbon group or the like.

[0085] When the total content of the resin components in the resin composition is 100 parts by mass, the content of the curing agent (C) contained in the resin composition of this embodiment is preferably 0.05 part by mass or more, more preferably 0.1 part by mass or more, even more preferably 0.2 part by mass or more, and preferably 10.0 parts by mass or less, more preferably 8.0 parts by mass or less, even more preferably 6.0 parts by mass or less.

[0086] When the curing agent (C) contains at least one selected from the group consisting of a photo cationic polymerization initiator and a thermal cationic polymerization initiator, the content of the curing agent (C) contained in the resin composition of the present embodiment is preferably 0.05 parts by mass or more, more preferably 0.1 parts by mass or more, still more preferably 0.2 parts by mass or more, and preferably 1.0 part by mass or less, more preferably 0.7 parts by mass or less, still more preferably 0.5 parts by mass or less when the total content of the resin components in the resin composition is 100 parts by mass.

[0087] When the curing agent (C) contains an imidazole-based compound, the content of the curing agent (C) contained in the resin composition of the present embodiment is preferably 1.0 part by mass or more, more preferably 2.0 parts by mass or more, still more preferably 4.0 parts by mass or more, and preferably 10.0 parts by mass or less, more preferably 8.0 parts by mass or less, still more preferably 6.0 parts by mass or less when the total content of the resin components in the resin composition is 100 parts by mass.

[0088] The curing agent (C) of the present embodiment may be a single curing agent or may contain two or more curing agents.

[0089] <Surfactant (D)> From the viewpoint of further improving the embedability, the resin composition of the present embodiment preferably further contains a surfactant (D). The surfactant (D) includes, for example, silicone-based surfactants, fluorine-based surfactants, etc., and preferably contains a silicone-based surfactant. The surfactant (D) of the present embodiment may be a single surfactant or may contain two or more surfactants.

[0090] When the total content of the resin components in the resin composition of the present embodiment is 100 parts by mass, the content of the surfactant (D) contained in the resin composition of the present embodiment is preferably 0.01 part by mass or more, more preferably 0.05 part by mass or more, still more preferably 0.07 part by mass or more, and preferably 3.0 parts by mass or less, more preferably 1.0 part by mass or less, still more preferably 0.7 part by mass or less, still more preferably 0.5 part by mass or less, still more preferably 0.3 part by mass or less.

[0091] <Organic solvent (E)> The resin composition of the present embodiment may contain an organic solvent (E). When the resin composition of the present embodiment contains an organic solvent (E), it can be made into a varnish-like resin composition.

[0092] Examples of the organic solvent (E) of the present embodiment include acetone, methyl ethyl ketone, methyl amyl ketone, toluene, propylene glycol monomethyl ether, 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. The organic solvent (E) of the present embodiment may be a single organic solvent or may contain two or more organic solvents.

[0093] When the resin composition of the present embodiment contains an organic solvent (E), the concentration of the total solid content (non-volatile component) in the resin composition is preferably 10% by mass or more, more preferably 20% by mass or more, still more preferably 30% by mass or more, still more preferably 35% by mass or more, from the viewpoint of appropriately controlling the viscosity of the resin composition, and preferably 60% by mass or less, more preferably 55% by mass or less, still more preferably 50% by mass or less, from the viewpoint of sufficiently dissolving each component in the resin composition.

[0094] <Other components> The resin composition of the present embodiment may further contain, for example, a curing aid, a leveling agent, a coloring agent, a storage stabilizer, a plasticizer, a filler, inorganic particles, an anti-degradant, a wettability improver, an antistatic agent, etc. The content of other components is an appropriate amount.

[0095] When the total content of the cyclic olefin resin (A) and the compound (B) having a cyclic ether structure in the resin composition of the present embodiment is 100% by mass based on the total content of the resin components in the resin composition, it is preferably 80% by mass or more, more preferably 85% by mass or more, still more preferably 90% by mass or more, still more preferably 95% by mass or more, still more preferably 98% by mass or more, from the viewpoint of suppressing a decrease in light transmittance and further improving the embeddability, and the upper limit value of the total content is not particularly limited, but is, for example, 100% by mass or less. When the total content of the cyclic olefin resin (A) and the compound (B) having a cyclic ether structure in the resin composition of the present embodiment is 100% by mass based on the total content of all components in the resin composition, it is preferably 10% by mass or more, more preferably 20% by mass or more, still more preferably 30% by mass or more, still more preferably 35% by mass or more, still more preferably 50% by mass or more, still 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, still more preferably 92% by mass or more, and the upper limit value is not particularly limited, but is, for example, less than 100% by mass, 99% by mass or less.

[0096] When the total content of the cyclic olefin resin (A), the compound (B) having a cyclic ether structure, and the curing agent (C) in the resin composition of the present embodiment is 100% by mass based on the total content of all components in the resin composition, it is preferably 10% by mass or more, more preferably 20% by mass or more, still more preferably 30% by mass or more, still more preferably 35% by mass or more, still more preferably 50% by mass or more, still 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, still more preferably 95% by mass or more, and the upper limit is not particularly limited, but is, for example, 100% by mass or less.

[0097] [Method for producing resin composition] The resin composition of the present embodiment can be obtained, for example, by mixing each component. The resin composition of the present embodiment in film form can be obtained, for example, by applying and drying a varnish-like resin composition on a base film.

[0098] [Resin film] The resin film of the present embodiment is a resin film made of the resin composition of the present embodiment. The resin film of the present embodiment includes not only the resin film alone but also a resin film formed on a base film and the like.

[0099] From the viewpoint of further improving the light propagation efficiency of the optical waveguide, the light transmittance of the resin film of the present embodiment at a wavelength of 850 nm is preferably 85% or more, more preferably 90% or more, still more preferably 95% or more, still more preferably 97% or more, still more preferably 98% or more. The light transmittance of the resin film at a wavelength of 850 nm can be measured by an ultraviolet-visible spectrophotometer.

[0100] From the viewpoint of further improving the embeddability, the thickness of the resin film of the present embodiment is preferably 1 μm or more, more preferably 3 μm or more, still more preferably 5 μm or more, still more preferably 8 μm or more, and from the viewpoint of further improving the light propagation efficiency of the optical waveguide, it is preferably 150 μm or less, more preferably 130 μm or less, still more preferably 100 μm or less, still more preferably 70 μm or less, still more preferably 50 μm or less, still more preferably 30 μm or less.

[0101] The resin film of the present embodiment can be obtained, for example, from the varnish-like resin composition of the present embodiment as a raw material by a known method for forming a coating film.

[0102] [Film] The film of the present embodiment includes a resin layer formed of the resin composition of the present embodiment. The film of the present embodiment is preferably a dry film.

[0103] From the viewpoint of further improving the handleability of the film, the thickness of the film of the present embodiment is preferably 10 μm or more, more preferably 30 μm or more, still more preferably 50 μm or more, still more preferably 60 μm or more, still more preferably 80 μm or more, and preferably 250 μm or less, more preferably 200 μm or less, still more preferably 150 μm or less.

[0104] From the viewpoint of further improving the embeddability, the thickness of the resin layer of the present embodiment is preferably 1 μm or more, more preferably 3 μm or more, still more preferably 5 μm or more, still more preferably 8 μm or more, and from the viewpoint of further improving the light propagation efficiency of the optical waveguide, it is preferably 150 μm or less, more preferably 130 μm or less, still more preferably 100 μm or less, still more preferably 70 μm or less, still more preferably 50 μm or less, still more preferably 30 μm or less.

[0105] The film of the present embodiment further preferably includes a base film, and the resin layer is preferably provided on the base film. As the base film, for example, a resin film can be used. The resin constituting the base film is not particularly limited, but preferably contains at least one or two or more selected from the group consisting of polyimide and polyethylene terephthalate.

[0106] From the viewpoint of further improving the handleability of the film, the thickness of the base film of this embodiment is preferably 10 μm or more, more preferably 15 μm or more, still more preferably 20 μm or more, and preferably 100 μm or less, more preferably 80 μm or less, still more preferably 60 μm or less, and still more preferably 40 μm or less.

[0107] The base film of this embodiment may be subjected to surface treatments such as antistatic treatment and release treatment.

[0108] The film of this embodiment may further include a cover film. The cover film is preferably provided so as to be in direct contact with the resin layer. When the film of this embodiment includes a base film, the cover film is preferably provided on the surface of the resin layer opposite to the base film. The cover film is not particularly limited, and for example, an OPP cover film can be used.

[0109] The film of this embodiment can be obtained, for example, by applying and drying the varnish-like resin composition of this embodiment on a base film. Examples of the application method include a method of directly applying using various coater devices such as a pin coater, a die coater, a comma coater, and a curtain coater, and a printing method such as screen printing.

[0110] [Film set] The film set of this embodiment includes a first film and a second film, and at least one of the first film and the second film is the film of this embodiment. In the film set of this embodiment, it is preferable that both the first film and the second film are the films of this embodiment.

[0111] [Optical waveguide] The optical waveguide of this embodiment will be described with reference to FIG. 1. The optical waveguide 100 of this embodiment is an optical waveguide in which a first cladding layer 20, a core layer 30, and a second cladding layer 40 are laminated in this order, and at least one of the first cladding layer 20 and the second cladding layer 40 contains the resin composition of this embodiment. In the optical waveguide of this embodiment, it is preferable that both the first cladding layer 20 and the second cladding layer 40 contain the resin composition of this embodiment.

[0112] When the optical waveguide 100 is provided on the substrate 110, it is preferable that the first cladding layer 20 is on the substrate 110 side. When the first cladding layer 20 is on the substrate 110 side, the preferable thicknesses of the first cladding layer 20 and the second cladding layer 40 are as follows. The thickness of the first cladding layer 20 is preferably 1 μm or more, more preferably 3 μm or more, still more preferably 5 μm or more, still more preferably 8 μm or more, still more preferably 10 μm or more, still more preferably 15 μm or more, still more preferably 20 μm or more from the viewpoint of further improving the embedding property, and preferably 150 μm or less, more preferably 100 μm or less, still more preferably 70 μm or less, still more preferably 50 μm or less, still more preferably 40 μm or less, still more preferably 30 μm or less from the viewpoint of further improving the light propagation efficiency of the optical waveguide. The thickness of the second cladding layer 40 is preferably 1 μm or more, more preferably 3 μm or more, still more preferably 5 μm or more, still more preferably 8 μm or more from the viewpoint of further suppressing the thermal shrinkage of the optical waveguide, and preferably 150 μm or less, more preferably 100 μm or less, still more preferably 70 μm or less, still more preferably 50 μm or less, still more preferably 40 μm or less, still more preferably 30 μm or less, still more preferably 20 μm or less.

[0113] The material for forming the core layer 30 is not particularly limited, and for example, it is formed from a resin composition. As the resin for forming the core layer 30, for example, a resin used for the core of a known optical waveguide can be used, but it preferably contains a cyclic olefin resin, and more preferably contains a norbornene resin. The resin composition for forming the core layer 30 may contain an antioxidant, a photo cationic polymerization initiator, and the like.

[0114] The thickness of the core layer 30 is preferably 1 μm or more, more preferably 5 μm or more, still more preferably 10 μm or more, still more preferably 20 μm or more, still more preferably 30 μm or more, and preferably 100 μm or less, more preferably 80 μm or less, still more preferably 60 μm or less, still more preferably 50 μm or less.

[0115] A waveguide pattern may be formed on the core layer 30. Examples of the method for forming the waveguide pattern include an exposure method, an etching method, a replication method, and the like.

[0116] The optical waveguide 100 may have a mirror formed thereon, and the mirror 50 on the light emitting element side and the mirror 60 on the light receiving element side may be formed. Examples of the method for forming the mirror include a method of forming an inclined surface by laser processing or the like.

[0117] In addition to the first cladding layer 20, the core layer 30, and the second cladding layer 40, the optical waveguide 100 may include other layers as long as they do not affect the good performance of the optical waveguide 100.

[0118] [Optoelectronic composite substrate] The optoelectronic composite substrate of this embodiment will be described with reference to FIG. 1. The optoelectronic composite substrate 200 includes a substrate 110 and an optical waveguide 100 provided on the substrate 110.

[0119] The substrate 110 includes, for example, a printed circuit board, a flexible substrate, etc., and is preferably a flexible substrate. The substrate 110 may have vias 140 formed therein.

[0120] The optoelectronic composite substrate 200 may further include a polyimide base material (not shown) on the surface opposite to the core layer 30 of the second cladding layer 40.

[0121] The optoelectronic composite substrate 200 may include a light-emitting element 120, a light-receiving element 130, etc.

[0122] The optoelectronic composite substrate 200 is obtained, for example, by: (i) forming a first cladding layer 20 on the substrate 110; (ii) forming a core layer 30 on the first cladding layer 20; and (iii) forming a second cladding layer 40 on the core layer 30. Examples of the method for forming each layer include a method of sequentially laminating each layer by roll lamination, vacuum roll lamination, flat lamination, vacuum flat lamination, atmospheric pressure pressing, vacuum pressing, etc. of a film for forming each layer.

[0123] [Electronic Component] The electronic component of this embodiment includes the optoelectronic composite substrate of this embodiment. Examples of the electronic component of this embodiment include electronic components in electronic devices such as mobile phones, game consoles, router devices, WDM devices, personal computers, televisions, home servers, etc.

[0124] The embodiments of the present invention have been described above, but these are examples of the present invention, and various configurations other than those described above can also be adopted. Moreover, the present invention is not limited to the above-described embodiments, and modifications, improvements, etc. within the scope that can achieve the object of the present invention are included in the present invention.

Examples

[0125] Hereinafter, this embodiment will be described in detail based on examples and comparative examples. Note that this embodiment is not limited to the descriptions of these examples at all.

[0126] [Raw materials] First, the raw materials used in the examples and comparative examples will be described.

[0127] >[Synthesis of cyclic olefin resin] >[Synthesis of cyclic olefin resin (A-1)] In a reaction vessel of appropriate size equipped with a stirrer and a cooling pipe, 470.8 g (5.0 mol) of 2-norbornene, 490.3 g (5.0 mol) of maleic anhydride, and 23.0 g (0.10 mol) of dimethyl 2,2'-azobis(2-methylpropionate) were weighed and dissolved in 1607 g of methyl ethyl ketone and 689 g of toluene. Next, after removing the dissolved oxygen in the system by nitrogen bubbling, the container was sealed and reacted at 70 °C for 16 hours. After cooling the obtained solution to room temperature, it was reprecipitated in a large amount of heptane to obtain a polymer precipitate. Subsequently, the polymer was filtered off with a suction filter, and the powder was further washed with heptane and then dried in a dryer at 60 °C for 24 hours to obtain cyclic olefin resin (A-1). The weight average molecular weight (Mw) of cyclic olefin resin (A-1) by GPC measurement was 11,000, and the refractive index under the conditions of 23 °C and 589 nm by Abbe refractometer measurement was 1.51. Cyclic olefin resin (A-1) is a resin containing a structural unit represented by formula (a-1) and a structural unit represented by formula (b-2).

[0128] >[Synthesis of cyclic olefin resin (A-2)] In a reaction vessel of appropriate size equipped with a stirrer and a cooling pipe, 470.8 g (5.0 mol) of 2-norbornene, 860.9 g (5.0 mol) of 1-butyl hydrogen maleate, and 23.0 g (0.10 mol) of dimethyl 2,2'-azobis(2-methylpropionate) were weighed and dissolved in 2213 g of methyl ethyl ketone and 948 g of toluene. Subsequently, after removing the dissolved oxygen in the system by nitrogen bubbling, the vessel was sealed and reacted at 70 °C for 16 hours. After cooling the resulting solution to room temperature, it was reprecipitated into a large amount of heptane to obtain a polymer precipitate. Subsequently, the polymer was filtered off with a suction filter, and the powder was further washed with heptane and then dried in a dryer at 60 °C for 24 hours to obtain a cyclic olefin resin (A-2). The weight-average molecular weight (Mw) of the cyclic olefin resin (A-2) by GPC measurement was 12,000, and the refractive index under the conditions of 23 °C and 589 nm by Abbe refractometer measurement was 1.51. The cyclic olefin resin (A-2) is a resin containing a structural unit represented by the formula (a-1) and a structural unit represented by the formula (b-3).

[0129] (Synthesis of cyclic olefin resin (A-3)) In a reaction vessel of appropriate size equipped with a stirrer and a cooling pipe, 450 g (2.5 mol) of methyl glycidyl ether norbornene, 235 g (2.5 mol) of 2-norbornene, 516.5 g (3.0 mol) of 1-butyl hydrogen maleate, 245 g (2.5 mol) of maleic anhydride, and 23.0 g (0.1 mol) of dimethyl 2,2'-azobis(2-methylpropionate) were weighed and dissolved in 2401 g of methyl ethyl ketone and 1029 g of toluene. Subsequently, after removing the dissolved oxygen in the system by nitrogen bubbling, the vessel was sealed and reacted at 70 °C for 16 hours. After cooling the resulting solution to room temperature, it was reprecipitated into a large amount of heptane to obtain a polymer precipitate. Subsequently, the polymer was filtered off with a suction filter, and the powder was further washed with heptane and then dried in a dryer at 60 °C for 24 hours to obtain a resin of cyclic olefin resin (A-3). The weight average molecular weight (Mw) of the cyclic olefin resin (A-3) by GPC measurement was 6,300, and the refractive index under the conditions of 23 °C and 589 nm by Abbe refractometer measurement was 1.51. The cyclic olefin resin (A-3) is a resin containing a structural unit represented by the formula (a-1), a structural unit represented by the formula (b-2), and a structural unit represented by the formula (b-3).

[0130] (Synthesis of cyclic olefin resin (A-4)) In a reaction vessel of appropriate size equipped with a stirrer and a cooling tube, 345.4 g (2.5 mol) of 5-norbornene-2-carboxylic acid, 355.0 g (2.5 mol) of ethyloxetane vinyl ether, 242.7 g (2.5 mol) of maleimide, 448.1 g (2.5 mol) of N-cyclohexylmaleimide, and 23.0 g (0.1 mol) of dimethyl 2,2'-azobis(2-methylpropionate) were weighed and dissolved in 2310 g of methyl ethyl ketone and 990 g of toluene. Next, after removing the dissolved oxygen in the system by nitrogen bubbling, the vessel was sealed and reacted at 70 °C for 16 hours. After cooling the obtained solution to room temperature, it was reprecipitated in a large amount of heptane to obtain a polymer precipitate. Subsequently, the polymer was filtered off with a suction filter, and the powder was further washed with heptane and then dried in a dryer at 60 °C for 24 hours to obtain the cyclic olefin resin (A-4). The weight average molecular weight (Mw) of the cyclic olefin resin (A-4) by GPC measurement was 11,500, and the refractive index of the cyclic olefin resin (A-4) under the conditions of 23 °C and 589 nm by Abbe refractometer measurement was 1.51. The cyclic olefin resin (A-4) is a resin containing a structural unit represented by the formula (a-1) and a structural unit represented by the formula (b-1).

[0131] (Synthesis of cyclic olefin resin (A-5)) Into a suitable-sized reaction vessel equipped with a stirrer and a cooling pipe, 900 g (5.0 mol) of methyl glycidyl ether norbornene, 242.7 g (2.5 mol) of maleimide, 448.1 g (2.5 mol) of N-cyclohexyl maleimide, and 23.0 g (0.1 mol) of dimethyl 2,2'-azobis(2-methylpropionate) were weighed and dissolved in 2636 g of methyl ethyl ketone and 1130 g of toluene. Next, after removing the dissolved oxygen in the system by nitrogen bubbling, the vessel was sealed and reacted at 70 °C for 16 hours. After cooling the obtained solution to room temperature, it was reprecipitated in a large amount of heptane to obtain a polymer precipitate. Subsequently, the polymer was filtered off with a suction filter, and the powder was further washed with heptane and then dried in a dryer at 60 °C for 24 hours to obtain a cyclic olefin resin (A-5). The weight-average molecular weight (Mw) of the cyclic olefin resin (A-5) by GPC measurement was 8,500, and the refractive index of the cyclic olefin resin (A-5) under the conditions of 23 °C and 589 nm by Abbe refractometer measurement was 1.51. The cyclic olefin resin (A-5) is a resin containing a structural unit represented by the formula (a-1) and a structural unit represented by the formula (b-1).

[0132] (Synthesis of cyclic olefin resin (A-6)) <For comparative example> The inside of a reaction vessel equipped with a stirrer and a cooling pipe was first thoroughly replaced with nitrogen, and then 164 g (0.7 mol) of decyl norbornene, 54.1 g (0.3 mol) of methyl glycidyl ether norbornene, and 800 g of toluene were charged, and the mixture was heated to 50 °C in an oil bath while stirring. A toluene solution (5 g) of 6.9 g (0.014 mol) of (toluene)Ni(C6F5)2 was added thereto, and the reaction was further carried out at 50 °C for 3 hours. After the obtained solution was reprecipitated in a large amount of methanol to obtain a polymer precipitate, it was filtered off with a suction filter to obtain a polymer powder. The obtained polymer was vacuum dried at 60 °C for 16 hours to obtain a cyclic olefin resin (A-6). The weight-average molecular weight (Mw) of the cyclic olefin resin (A-6) by GPC measurement was 100,000, and the refractive index of the cyclic olefin resin (A-6) under the conditions of 23 °C and 589 nm by Abbe refractometer measurement was 1.50. The cyclic olefin resin (A-6) is a resin that contains the structural unit (a) but does not contain the structural unit (b).

[0133] (Synthesis of cyclic olefin resin (A-8)) Into a reaction vessel of appropriate size equipped with a stirrer and a cooling tube, 540 g (3.0 mol) of methyl glycidyl ether norbornene, 1855 g (7.0 mol) of N-dodecyl maleimide, and 23.0 g (0.1 mol) of dimethyl 2,2'-azobis(2-methylpropionate) were weighed and dissolved in 3949 g of methyl ethyl ketone and 1693 g of toluene. Next, after removing the dissolved oxygen in the system by nitrogen bubbling, the vessel was sealed and reacted at 70 °C for 16 hours. After cooling the obtained solution to room temperature, it was reprecipitated in a large amount of heptane to obtain a polymer precipitate. Subsequently, the polymer was filtered off with a suction filter, and the powder was further washed with heptane and then dried in a dryer at 60 °C for 24 hours to obtain the cyclic olefin resin (A-8). The weight average molecular weight (Mw) of the cyclic olefin resin (A-8) by GPC measurement was 12,000, and the refractive index of the cyclic olefin resin (A-8) under the conditions of 23 °C and 589 nm by Abbe refractometer measurement was 1.52. The cyclic olefin resin (A-8) is a resin containing a structural unit represented by the formula (a-1) and a structural unit represented by the formula (b-1).

[0134] The details of the raw materials of each component in Table 1 are as follows.

[0135] <Resin (A)> (A-1) The cyclic olefin resin synthesized above (A-2) The cyclic olefin resin synthesized above (A-3) The cyclic olefin resin synthesized above (A-4) The cyclic olefin resin synthesized above (A-5) The cyclic olefin resin synthesized above (A-6) The cyclic olefin resin synthesized above (for comparative example) (A-7) JER-1256 (manufactured by Mitsubishi Chemical Corporation, aromatic phenoxy resin) (for comparative example) (A-8) Cyclic olefin resin synthesized above

[0136] [Chemical formula]

[0137] (Compound (B) having a cyclic ether structure) (B-1) Celloxide 2021P (manufactured by Daicel Corporation, an epoxy compound having an alicyclic structure, liquid at 23°C, refractive index 1.51) (B-2) EHPE-3150 (manufactured by Daicel Corporation, an epoxy compound having an alicyclic structure, solid at 23°C, refractive index 1.51) (B-3) Epicoat YX-8000 (manufactured by Mitsubishi Chemical Corporation, an epoxy compound having an alicyclic structure, liquid at 23°C, refractive index 1.51) (B-4) Denacol EX-321L (manufactured by Nagase ChemteX Corporation, an aliphatic epoxy compound, liquid at 23°C, refractive index 1.50) (B-5) OXT-221 (manufactured by Toagosei Co., Ltd., an oxetane compound, liquid at 23°C, refractive index 1.50)

[0138] [Chemical formula]

[0139] (Hardener (C)) (C-1) CPI-310B (manufactured by San-Apro Ltd., a photo cationic polymerization initiator) (C-2) Sun-Aid SI-B5 (manufactured by Sanshin Chemical Industry Co., Ltd., a thermal cationic polymerization initiator) (C-3) Curezol C11z (manufactured by Shikoku Kasei Co., Ltd., an imidazole-based compound)

[0140] (Surfactant (D)) (D-1) BYK-333 (manufactured by BYK-Chemie Japan Co., Ltd., a silicone-based surfactant)

[0141] (Organic solvent (E)) (E-1) 2-Butanone (E-2) Propylene Glycol Monomethyl Ether Acetate (E-3) Propylene Glycol Monomethyl Ether

[0142] [Examples 1 - 10, 21 and Comparative Examples 1 - 3] (Preparation of Resin Composition) Each raw material compounded according to Table 1 was stirred at room temperature until the raw materials were completely dissolved to obtain a solution. Then, the solution was filtered through a PTFE filter with a pore size of 0.2 μm to obtain the varnish-like resin compositions of Examples 1 - 10, 21 and Comparative Examples 1 - 3, respectively.

[0143] (Preparation of Film) The resin compositions of Examples 1 - 10, 21 and Comparative Examples 1 - 3 obtained in the preparation of the above resin composition were applied as a varnish using an applicator onto a polyethylene terephthalate substrate with an antistatic treatment having a thickness of 38 μm so that the thickness after drying was the thickness of the resin layer described in Table 1, then dried at 100 °C for 10 minutes, and finally an OPP cover film was attached to the surface on the resin layer side formed by the resin composition to prepare films, and the films of Examples 1 - 10, 21 and Comparative Examples 1 - 3 were obtained, respectively.

[0144] [Examples 11 - 20, 22 and Comparative Examples 4, 5] (Synthesis of Polymer for Core Layer Formation) In a glove box in which both the moisture and oxygen concentrations were controlled to 1 ppm or less and filled with dry nitrogen, 7.2 g (40.1 mmol) of hexylnorbornene (HxNB) and 12.9 g (40.1 mmol) of diphenylmethylnorbornenemethoxysilane were weighed into a 500 mL vial, 60 g of dehydrated toluene and 11 g of ethyl acetate were added, and the top was sealed with a silicone sealer. Next, 1.56 g (3.2 mmol) of Ni catalyst and 10 mL of dehydrated toluene were weighed into a 100 mL vial bottle, a stirrer chip was added, and the bottle was sealed. The Ni catalyst was stirred thoroughly to be completely dissolved, and a Ni catalyst solution was obtained. 1 mL of the Ni catalyst solution was accurately weighed with a syringe and quantitatively injected into the vial bottle in which the above two kinds of norbornenes were dissolved, and stirred at room temperature for 1 hour. At this time, a significant increase in viscosity was confirmed. At this point, the stopper was removed, 60 g of tetrahydrofuran (THF) was added and stirred to obtain a reaction solution. 9.5 g of acetic anhydride, 18 g of hydrogen peroxide solution (concentration 30%), and 30 g of ion-exchanged water were added to a 100 mL beaker and stirred to prepare a peracetic acid aqueous solution. Next, the total amount of the peracetic acid aqueous solution was added to the above reaction solution and stirred for 12 hours to perform the reduction treatment of Ni. Next, the treated reaction solution was transferred to a separatory funnel. After removing the lower aqueous layer, 100 mL of a 30% aqueous solution of isopropyl alcohol was added and stirred vigorously. After standing for complete two-layer separation, the aqueous layer was removed. This water washing process was repeated a total of 3 times. Then, the oil layer was dropped into a large excess of acetone to reprecipitate the generated polymer, separated from the filtrate by filtration, and then heated and dried in a vacuum dryer set at 60 °C for 12 hours to obtain a polymer for core layer formation.

[0145] As a result of GPC measurement, the molecular weight of the polymer for core layer formation was Mw = 100,000 and Mn = 40,000. Also, as a result of identification by NMR measurement, the molar ratio of each structural unit in the polymer for core layer formation was 50 mol% of hexyl norbornene structural unit and 50 mol% of diphenylmethyl norbornene methoxysilane structural unit.

[0146] (Preparation of Resin Composition for Core Layer Formation) Weighed 10 g of the purified polymer for forming the core layer into a 100 mL glass container, added 30 g of methylcyclohexane, 2.4 g of an oxetane compound (manufactured by Toagosei Co., Ltd., product name: OXT-213), 0.8 g of an epoxy compound (manufactured by Daicel Corporation, product name: Celoxide 2021P), 0.03 g of a photo cationic polymerization initiator (manufactured by San-Apro Ltd., product name: CPI-310B), and 0.1 g of an antioxidant (manufactured by BSF, product name: Irganox 1076), dissolved them uniformly, and then filtered through a 0.2 μm PTFE filter to obtain a resin composition for forming the core layer.

[0147] (Fabrication of Dry Film for Core Layer Formation) The obtained resin composition for forming the core layer was applied onto a PET film subjected to a release treatment using an applicator so that the film thickness after drying was 40 μm. After application, it was placed in a dryer at 45°C for 5 minutes to completely remove the solvent and form a film, thereby obtaining a dry film for forming the core layer.

[0148] (Fabrication of Core Layer) Using a direct drawing exposure machine (manufactured by SCREEN Co., Ltd., product name: LI-9000), ultraviolet rays with an exposure amount of 100 mJ / cm 2 were irradiated onto the obtained dry film for forming the core layer, and 20 line-and-space patterns with a length of 9 cm, an exposed part of 10 μm, and an unexposed part of 50 μm were formed. Subsequently, it was placed in an oven at 160°C for 1 hour to obtain a core layer. It was confirmed that distinct waveguide patterns (a plurality of core parts) with a rectangular cross-section appeared in the obtained core layer.

[0149] (Fabrication of Optoelectronic Composite Substrate) In the fabrication of the optoelectronic composite substrate, the film of the first cladding layer and the film of the second cladding layer respectively refer to the cladding films described in Table 2. Note that the types of claddings described in Table 2 refer to the types of claddings described in Table 1. For example, "Cladding A" refers to the film obtained in Example 1. First, place a double-sided copper-clad laminate cut to 24 cm × 16 cm on a stainless-steel plate, peel off the OPP cover film of the film of the first clad layer, and use a vacuum laminator (manufactured by Nichco Materials Co., Ltd., product name: CVP-300) so that the double-sided copper-clad laminate and the first clad layer are in contact with each other. Laminating was performed under the conditions of temperature: 140 °C, pressure: 0.5 MPa, and time: 120 seconds to obtain a laminate. After peeling off the PET film derived from the film of the first clad layer, using a direct drawing exposure machine (manufactured by SCREEN Co., Ltd., product name: LI-9000), ultraviolet rays with an exposure amount of 1000 mJ / cm 2 were irradiated over the entire surface, and then heated in an oven at 120 °C for 1 hour to obtain a laminate 1 having a layer structure of "double-sided copper-clad laminate / first clad layer".

[0150] After performing oxygen plasma treatment on the core layer in the dry film for core layer formation after the above (production of the core layer) treatment, using a vacuum laminator, laminate under the same conditions as the lamination treatment of laminate 1 so that the first clad layer and the core layer in laminate 1 are in contact with each other. The PET film derived from the dry film for core layer formation was peeled off to obtain a laminate 2 having a layer structure of "double-sided copper-clad laminate / first clad layer / core layer".

[0151] Next, after performing oxygen plasma treatment on the core layer of laminate 2, peel off the cover film of the film of the second clad layer, and use a vacuum laminator to laminate under the same conditions as the lamination treatment of laminate 1 so that the core layer and the second clad layer in laminate 2 are in contact with each other. The PET film derived from the film of the second clad layer was peeled off to obtain a laminate 3 having a layer structure of "double-sided copper-clad laminate / first clad layer / core layer / second clad layer".

[0152] Next, using a vacuum laminator, laminate under the same conditions as the lamination treatment of laminate 1 so that the second clad layer in laminate 3 and the polyimide base material (manufactured by UBE Industries, Ltd., product name: Upilex 25S, thickness 25 μm) are in contact with each other, and obtain a laminate 4 having a layer structure of "double-sided copper-clad laminate / first clad layer / core layer / second clad layer / polyimide base material".

[0153] The obtained laminate 4 was heat-treated in an oven at 180°C for 1 hour to obtain the optoelectronic composite substrates of Examples 11 to 20, 22 and Comparative Examples 4 and 5, respectively.

[0154] [Evaluation] The evaluation methods for the examples and comparative examples are described below.

[0155] <Evaluation of coatability> The appearances of the films of Examples 1 to 10, 21 and Comparative Examples 1 to 3 were observed, and samples without appearance abnormalities such as those of Standard B were evaluated as A, and samples with appearance abnormalities (coating unevenness, cloudiness, peeling, cracking, etc.) were evaluated as B.

[0156] <Evaluation of refractive index> For the films of Examples 1 to 10, 21 and Comparative Examples 1 to 3, the OPP cover film was peeled off, and the refractive index was measured at 23°C and 589 nm using an Abbe refractometer (manufactured by Atago Co., Ltd., product name: NAR-1T SOLID). A lower refractive index is preferable from the viewpoint of increasing the refractive index difference from the core layer.

[0157] <Measurement of light transmittance at a wavelength of 850 nm> For the films of Examples 1 to 10, 21 and Comparative Examples 1 to 3, the OPP cover film was peeled off, and the resin layer side formed by the resin composition was laminated on a slide glass at a temperature of 100°C, a pressure of 0.5 MPa, and a time of 2 minutes so that the resin layer side faced the slide glass side. Then, the base film was peeled off to obtain a transmittance measurement sample (slide glass with resin composition). Subsequently, 100% correction was performed with a UV-visible spectrophotometer (manufactured by JASCO Corporation, product name: V-670) with slide glasses placed in both the background slot and the sample slot, and the slide glass on the measurement slot side was replaced with the transmittance measurement sample, and the light transmittance [%] at a wavelength of 850 nm was measured in the transmittance measurement mode.

[0158] <Evaluation of embeddability> A double-sided copper-clad laminate (CCL) with a thickness of 50 μm and via holes with a diameter of 100 μm was prepared. The OPP cover films of the films of Examples 1 to 10, 21 and Comparative Examples 1 to 3 were peeled off, and after being pasted on the CCL so that the resin layer side formed by the resin composition faced the CCL side, it was laminated at a temperature of 100 °C, a pressure of 5.0 MPa, and a time of 2 minutes using a laminator. The via holes of the obtained substrates were observed with a microscope, and the samples that could be embedded without voids were evaluated as A, the samples with insufficient embedding were evaluated as B, and the samples with embedding defects such as bleeding after embedding were evaluated as C.

[0159] <Optical loss evaluation> For the optoelectronic composite substrates of Examples 11 to 20, 22 and Comparative Examples 4 and 5, both sides were cut by dicing so that the length of the pattern part became 7 cm, and samples for optical loss evaluation were obtained. For the samples for optical loss evaluation, the propagation loss was evaluated in accordance with the cut-back method of 4.6.2.1 of "Test Method for Polymer Optical Waveguides (JPCA-PE02-05-01S-2008)". In addition, light with a wavelength of 850 nm was used for the measurement. From the obtained results, the samples with a propagation loss of less than 1 dB were evaluated as A, the samples with a propagation loss of 1 dB to 3 dB were evaluated as B, and the samples with a propagation loss exceeding 3 dB were evaluated as C.

[0160] The evaluation results for each example and each comparative example are shown in Table 1 and Table 2, respectively.

[0161]

Table 1

[0162]

Table 2

[0163] From Table 1, all of the films of the examples had good evaluation results in the embedding property evaluation. Also, the films of the examples did not have a decrease in the light transmittance with respect to the wavelength of 850 nm like the film of Comparative Example 2. That is, it can be understood that according to the resin composition of the present embodiment, the embedding property can be improved while suppressing a decrease in the light transmittance.

[0164] From Table 2, all of the optoelectronic composite substrates of the examples had good evaluation results in the optical loss evaluation. That is, it can be understood that according to the optoelectronic composite substrate of the present embodiment, the propagation loss can be suppressed.

[0165] This application claims the priority based on Japanese Patent Application No. 2023-166734 filed on September 28, 2023, and incorporates all of the disclosures thereof herein.

Description of Reference Numerals

[0166] 20 First cladding layer 30 Core layer 40 Second cladding layer 50 Mirror on the light-emitting element side 60 Mirror on the light-receiving element side 100 Optical waveguide 110 Substrate 120 Light-emitting element 130 Light-receiving element 140a, 140b Via 200 Optoelectronic composite substrate

Claims

1. A resin composition that can be used for an optical waveguide clad, Contains a cyclic olefin resin (A), The cyclic olefin resin (A) contains a structural unit (a) and a structural unit (b), The structural unit (a) is a structural unit represented by the following formula (a-1): The resin composition, wherein the structural unit (b) is a structural unit represented by the following formula (b-1): 【Chemical 1】 (In formula (a-1), R １ , R ２ , R ３ and R ４ each independently represents a hydrogen atom, a hydroxyl group, or an organic group having 1 to 30 carbon atoms. 【Chemistry 2】 (In formula (b-1), R １１ represents a hydrogen atom, a hydroxyl group, or an organic group having 1 to 30 carbon atoms.

2. A resin composition that can be used for an optical waveguide clad, Contains a cyclic olefin resin (A), The cyclic olefin resin (A) contains a structural unit (a) and a structural unit (b), The structural unit (a) is a structural unit represented by the following formula (a-1): The structural unit (b) is one or more selected from the group consisting of a structural unit represented by the following formula (b-1), a structural unit represented by the following formula (b-2), and a structural unit represented by the following formula (b-3): The resin composition further comprises a compound (B) having a cyclic ether structure. 【Chemistry 3】 (In formula (a-1), R １ , R ２ , R ３ and R ４ each independently represents a hydrogen atom, a hydroxyl group, or an organic group having 1 to 30 carbon atoms. 【Chemistry 4】 (In formula (b-1), R １１ represents a hydrogen atom, a hydroxyl group, or an organic group having 1 to 30 carbon atoms. 【Chemistry 5】 【Chemistry 6】 (In formula (b-3), R ２１ and R ２２ each independently represents a hydrogen atom or an organic group having 1 to 30 carbon atoms.

3. A resin composition that can be used for an optical waveguide clad, Contains a cyclic olefin resin (A), The cyclic olefin resin (A) contains a structural unit (a) and a structural unit (b), The structural unit (a) is a structural unit represented by the following formula (a-1): The structural unit (b) is one or more selected from the group consisting of a structural unit represented by the following formula (b-1), a structural unit represented by the following formula (b-2), and a structural unit represented by the following formula (b-3): Further comprising a curing agent (C), The resin composition, wherein the curing agent (C) contains a cationic polymerization initiator. 【Chemistry 7】 (In formula (a-1), R １ , R ２ , R ３ and R ４ each independently represents a hydrogen atom, a hydroxyl group, or an organic group having 1 to 30 carbon atoms. 【Chemistry 8】 (In formula (b-1), R １１ represents a hydrogen atom, a hydroxyl group, or an organic group having 1 to 30 carbon atoms. 【Chemistry 9】 【Chemistry 10】 (In formula (b-3), R ２１ and R ２２ each independently represents a hydrogen atom or an organic group having 1 to 30 carbon atoms.

4. A resin composition that can be used for an optical waveguide clad, Contains a cyclic olefin resin (A), The cyclic olefin resin (A) contains a structural unit (a) and a structural unit (b), The structural unit (a) is a structural unit represented by the following formula (a-1): The structural unit (b) is one or more selected from the group consisting of a structural unit represented by the following formula (b-1), a structural unit represented by the following formula (b-2), and a structural unit represented by the following formula (b-3): Further comprising a curing agent (C), The resin composition, wherein the curing agent (C) contains an imidazole-based compound. 【Chemistry 11】 (In formula (a-1), R １ , R ２ , R ３ and R ４ each independently represents a hydrogen atom, a hydroxyl group, or an organic group having 1 to 30 carbon atoms. 【Chemistry 12】 (In formula (b-1), R １１ represents a hydrogen atom, a hydroxyl group, or an organic group having 1 to 30 carbon atoms. 【Chemistry 13】 【Chemistry 14】 (In formula (b-3), R ２１ and R ２２ each independently represents a hydrogen atom or an organic group having 1 to 30 carbon atoms.

5. The resin composition according to any one of claims 1 to 4, wherein the content of the structural unit (a) in the cyclic olefin resin (A) is 10 mol% or more and 70 mol% or less, when the total of all structural units in the cyclic olefin resin (A) is 100 mol%.

6. The resin composition according to any one of claims 1 to 4, wherein the refractive index of the cyclic olefin resin (A) is 1.45 or more and 1.55 or less.

7. The resin composition according to any one of claims 1 to 4, wherein the content of the cyclic olefin resin (A) in the resin composition is 20 parts by mass or more and 80 parts by mass or less, when the total content of the resin components in the resin composition is 100 parts by mass.

8. The resin composition according to any one of claims 1 and 3 to 4, further comprising a compound (B) having a cyclic ether structure.

9. A compound (B) having a cyclic ether structure, The resin composition according to any one of claims 1 to 4, wherein the compound (B) having a cyclic ether structure comprises at least one or more selected from the group consisting of epoxy compounds and oxetane compounds.

10. A compound (B) having a cyclic ether structure, The resin composition according to any one of claims 1 to 4, wherein the compound (B) having a cyclic ether structure contains an alicyclic structure in the molecule.

11. A compound (B) having a cyclic ether structure, The resin composition according to any one of claims 1 to 4, wherein the compound (B) having a cyclic ether structure contains two or more cyclic ether structures in the molecule.

12. A compound (B) having a cyclic ether structure, The resin composition according to any one of claims 1 to 4, wherein the compound (B) having a cyclic ether structure is liquid at 23°C.

13. A compound (B) having a cyclic ether structure, The resin composition according to any one of claims 1 to 4, wherein the refractive index of the compound (B) having a cyclic ether structure is 1.45 or more and 1.55 or less.

14. A compound (B) having a cyclic ether structure, The resin composition according to any one of claims 1 to 4, wherein the content of the compound (B) having a cyclic ether structure in the resin composition is 20 parts by mass or more and 80 parts by mass or less, when the total content of resin components in the resin composition is 100 parts by mass.

15. The resin composition according to claim 1 or 2, further comprising a curing agent (C).

16. Contains a curing agent (C), The resin composition according to any one of claims 1 to 2 and 4, wherein the curing agent (C) contains a cationic polymerization initiator.

17. Contains a curing agent (C), the curing agent (C) contains a cationic polymerization initiator, The resin composition according to any one of claims 1 to 4, wherein the cationic polymerization initiator comprises a photocationic polymerization initiator.

18. Contains a curing agent (C), the curing agent (C) contains a cationic polymerization initiator, The resin composition according to any one of claims 1 to 4, wherein the cationic polymerization initiator comprises a thermal cationic polymerization initiator.

19. Contains a curing agent (C), The resin composition according to any one of claims 1 to 3, wherein the curing agent (C) comprises an imidazole-based compound.

20. Contains a curing agent (C), The resin composition according to any one of claims 1 to 4, wherein the content of the curing agent (C) contained in the resin composition is 0.05 parts by mass or more and 10.0 parts by mass or less when the total content of resin components in the resin composition is 100 parts by mass.

21. The resin composition according to any one of claims 1 to 4, wherein the refractive index of the resin composition is 1.47 or more and 1.55 or less.

22. A resin film made of the resin composition according to any one of claims 1 to 4, The resin film has a light transmittance of 85% or more for a wavelength of 850 nm.

23. The resin film according to claim 22, wherein the resin film has a thickness of 1 μm or more and 150 μm or less.

24. A film that can be used for an optical waveguide clad, A film comprising a resin layer formed from the resin composition according to any one of claims 1 to 4.

25. Further, a base film is provided, The film according to claim 24, having the resin layer on the substrate film.

26. The film according to claim 25, wherein the resin constituting the base film comprises at least one or more selected from the group consisting of polyimide and polyethylene terephthalate.

27. 25. The film of claim 24, wherein the film is a dry film.

28. A film set that can be used for an optical waveguide clad, a first film and a second film; 25. A film set, wherein at least one of the first film and the second film is the film of claim 24.

29. An optical waveguide in which a first clad layer, a core layer, and a second clad layer are laminated in this order, An optical waveguide, wherein at least one of the first clad layer and the second clad layer comprises the resin composition according to any one of claims 1 to 4.

30. A substrate; An optical / electrical composite substrate comprising: the optical waveguide according to claim 29 provided on the substrate.

31. An electronic component comprising the optical-electrical composite substrate according to claim 30.

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