Dry film, resin composition, optical waveguide, photoelectric composite substrate and electronic component

Abstract

To provide a dry film and a resin composition which can suppress propagation loss of a photoelectric composite substrate.SOLUTION: A dry film 100 usable in a light waveguide cladding includes a resin layer 10 formed of a resin composition, wherein the resin composition contains a resin (A), a curing agent (B), and an ultraviolet absorber (C), and the resin layer 10 has light transmittance at a wavelength of 365 nm in terms of 50 μm thickness of 50% or less, and light transmittance at a wavelength of 430 nm in terms of 50 μm thickness of 50% or more.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] BACKGROUND ART In recent years, there has been a demand for components in information and communication devices that can realize more advanced information communication, such as larger information capacity and faster information communication speed, and optical waveguides are being considered as one such component.

[0003] As a technology relating to optical waveguides, for example, the technology described in Patent Document 1 can be mentioned.

[0004] Patent Document 1 describes a material for forming an optical waveguide having a lower cladding layer containing an ultraviolet absorber and a core layer. Patent Document 1 describes that the material for forming an optical waveguide is less likely to cause pattern thickening or development residue, and makes it possible to form a clear and fine pattern. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-48223 Summary of the Invention [Problem to be solved by the invention]

[0006] The present invention provides a dry film and a resin composition that can suppress the propagation loss of an optoelectronic composite substrate. [Means for solving the problem]

[0007] According to the present invention, there are provided the following dry film, resin composition, optical waveguide, optical / electrical composite substrate, and electronic component.

[0008] [1] A dry film that can be used for an optical waveguide clad, a resin layer formed from a resin composition; The resin composition includes a resin (A), a curing agent (B), and an ultraviolet absorber (C), the resin layer has a light transmittance of 50% or less at a wavelength of 365 nm and a thickness of 50 μm; The resin layer has a light transmittance of 50% or more at a wavelength of 430 nm and a thickness of 50 μm. [2] The dry film according to [1] above, wherein the ultraviolet absorber (C) comprises at least one selected from the group consisting of polyhydric phenol-based ultraviolet absorbers, benzotriazole-based ultraviolet absorbers, and triazine-based ultraviolet absorbers. [3] The dry film according to [1] or [2], wherein the content of the ultraviolet absorber (C) in the resin composition is 0.01% by mass or more and 3.0% by mass or less, when the total content of non-volatile components in the resin composition is 100% by mass. [4] The dry film according to any one of [1] to [3] above, wherein the curing agent (B) contains a photopolymerization initiator. [5] The dry film according to [4] above, wherein the photopolymerization initiator includes a photocationic polymerization initiator. [6] The dry film according to any one of the above [1] to [5], wherein the curing agent (B) contains a thermal polymerization initiator. [7] The dry film according to [6] above, wherein the thermal polymerization initiator includes a thermal cationic polymerization initiator. [8] The dry film according to any one of [1] to [7], wherein the content of the curing agent (B) in the resin composition is 0.01% by mass or more and 3.0% by mass or less, when the total content of non-volatile components in the resin composition is 100% by mass. [9] The dry film according to any one of [1] to [8] above, wherein the resin (A) contains a compound having a cyclic ether structure.

[10] The dry film according to [9] above, wherein the compound having a cyclic ether structure includes at least one selected from the group consisting of epoxy compounds and oxetane compounds.

[11] The dry film according to [9] or

[10] , wherein the content of the compound having a cyclic ether structure in the resin composition is 5% by mass or more and 70% by mass or less, when the total content of non-volatile components in the resin composition is 100% by mass.

[12] The dry film according to any one of [1] to

[11] above, wherein the resin (A) includes a resin having a norbornene structure.

[13] The dry film according to

[12] above, wherein the resin having a norbornene structure contains a structural unit represented by the following formula (1): [ka] (In the formula (1), R represents a hydrogen atom, a hydroxyl group, or an organic group having 1 to 30 carbon atoms.)

[14] The dry film according to

[13] , wherein the content of the structural unit represented by formula (1) in the resin having a norbornene structure is 5 mol % or more and 95 mol % or less, when the total of all structural units in the resin having a norbornene structure is 100 mol %.

[15] The dry film according to any one of

[12] to

[14] above, wherein the resin having a norbornene structure contains a structural unit represented by the following formula (2): [ka] (In the formula (2), X represents a divalent organic group having 1 to 30 carbon atoms, and Y represents a group having a cyclic ether structure.)

[16] The dry film according to any one of

[12] to

[15] , wherein the content of the resin having a norbornene structure in the resin composition is 20% by mass or more when the total content of non-volatile components in the resin composition is 100% by mass.

[17] The dry film according to any one of [1] to

[16] above, wherein the resin (A) includes a polyimide resin.

[18] The dry film according to any one of [1] to

[17] above, wherein the refractive index of the resin layer is 1.47 or more and 1.57 or less.

[19] The dry film according to any one of [1] to

[18] above, wherein the resin layer has a thickness of 1 μm or more and 150 μm or less.

[20] The dry film according to any one of [1] to

[19] above, wherein the resin layer has a light transmittance of 85% or more at a wavelength of 850 nm and a thickness of 50 μm. [twenty one] Further, a base film is provided, The dry film according to any one of [1] to

[20] above, which has the resin layer on the base film. [twenty two] The dry film according to

[21] above, wherein the resin constituting the base film includes at least one selected from the group consisting of polyethylene terephthalate and polyimide. [twenty three] A resin composition that can be used for an optical waveguide clad, A composition comprising a resin (A), a curing agent (B), and an ultraviolet absorber (C), a resin film formed from the resin composition has a light transmittance of 50% or less at a wavelength of 365 nm and a thickness of 50 μm; A resin composition, wherein a resin film formed from the resin composition has a light transmittance of 50% or more at a wavelength of 430 nm and a thickness of 50 μm. [twenty four] 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 is a layer formed by curing the resin layer in the dry film according to any one of [1] to

[22] above. [twenty five] A substrate; An optical / electrical composite substrate comprising: the optical waveguide according to

[24] provided on the substrate.

[26] An electronic component comprising the optical / electrical composite substrate according to

[25] . [Effects of the Invention]

[0009] According to the present invention, it is possible to provide a dry film and a resin composition that can suppress the propagation loss of an optoelectronic composite substrate. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a cross-sectional view schematically illustrating an example of the structure of a dry film according to an embodiment of the present invention. [Figure 2] 1 is a cross-sectional view schematically showing an example of the structure of an optoelectronic composite substrate according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, embodiments of the present invention will be described with reference to the drawings. The drawings are simplified and do not correspond to actual dimensional ratios. The numerical range "A to B" represents A or more and B or less unless otherwise specified. In this embodiment, the term "(meth)acrylate" represents a concept that includes both methacrylate and acrylate.

[0012] [Dry film] FIG. 1 is a cross-sectional view schematically showing an example of the structure of the dry film of this embodiment. The dry film 100 is a dry film that can be used for an optical waveguide clad, and includes a resin layer 10 formed from a resin composition, the resin composition including a resin (A), a curing agent (B), and an ultraviolet absorber (C), and the resin layer 10 has a light transmittance of 50% or less at a wavelength of 365 nm and a thickness of 50 μm, and the resin layer 10 has a light transmittance of 50% or more at a wavelength of 430 nm and a thickness of 50 μm.

[0013] FIG. 2 is a cross-sectional view showing a schematic example of the structure of an optical / electrical composite substrate according to this embodiment. The optical / electrical composite substrate 300 has an optical waveguide 200 provided on a substrate 30. The optical waveguide 200 has a first cladding layer 40, a core layer 50, and a second cladding layer 60 laminated in this order.

[0014] A method for manufacturing the optical-electrical composite substrate 300 includes, for example, a method including sequential steps of (i) forming a first cladding layer 40 on the substrate 30, (ii) forming a resin layer for forming a core layer on the first cladding layer 40, and (iii) exposing a portion of the resin layer for forming a core layer to light to form a waveguide pattern.

[0015] According to the inventor's investigations, it has been found that the optical / electrical composite substrate obtained by the above-mentioned method may have a large propagation loss. Although the cause of the large propagation loss is not clear, the inventor speculates that it may be due to the following.

[0016] For example, a double-sided copper-clad laminate is used as the substrate 30. When a portion of the core layer-forming resin layer is exposed to light, scratches and roughness (irregularities) on the copper foil surface in the double-sided copper-clad laminate cause diffuse reflection of light at the interface between the substrate 30 and the first clad layer 40. When light is diffusely reflected, the unexposed portion of the core layer-forming resin layer is also exposed, preventing the formation of the desired waveguide pattern and increasing the propagation loss of the resulting optoelectronic composite substrate.

[0017] Based on the above-mentioned assumed mechanism, the present inventors conducted extensive research and found for the first time that a dry film including a resin layer 10 formed from a resin composition, the resin composition including a resin (A), a curing agent (B), and an ultraviolet absorber (C), and the resin layer 10 having a light transmittance at a wavelength of 365 nm and a thickness of 50 μm and a light transmittance at a wavelength of 430 nm and a thickness of 50 μm within a specific range, can suppress propagation loss in an optoelectronic composite substrate.

[0018] The inventors believe that by setting the light transmittance of resin layer 10 at a wavelength of 365 nm and converted to a thickness of 50 μm to or less than the numerical value of the present invention, when a portion of the resin layer for forming a core layer is exposed to light, first clad layer 40 will absorb the light, and diffuse reflection of light at the interface between substrate 30 and first clad layer 40 can be suppressed, thereby suppressing propagation loss in the optical-electrical composite substrate.

[0019] From the viewpoint of further improving handleability, the thickness of the dry film 100 is preferably 10 μm or more and 250 μm or less, more preferably 30 μm or more and 200 μm or less, even more preferably 40 μm or more and 150 μm or less, even more preferably 60 μm or more and 140 μm or less, and even more preferably 80 μm or more and 130 μm or less.

[0020] Each layer of the dry film 100 will be specifically described below.

[0021] <Resin layer> The dry film 100 includes a resin layer 10 formed from a resin composition.

[0022] The resin layer 10 has a light transmittance of 50% or less at a wavelength of 365 nm and a thickness of 50 μm. The light transmittance of the resin layer 10 at a wavelength of 365 nm and a thickness of 50 μm is preferably 47% or less, more preferably 40% or less, even more preferably 30% or less, even more preferably 25% or less, and even more preferably 20% or less, from the viewpoint of further suppressing propagation loss in the optoelectronic composite substrate, and the lower limit is not particularly limited, but may be, for example, 0% or more or 1% or more. Furthermore, the light transmittance of the resin layer 10 at a wavelength of 365 nm and a thickness of 50 μm is preferably 0% or more and 47% or less, more preferably 0% or more and 40% or less, even more preferably 0% or more and 30% or less, even more preferably 0% or more and 25% or less, and even more preferably 1% or more and 20% or less, from the viewpoint of further suppressing propagation loss in the optoelectronic composite substrate.

[0023] The light transmittance of the resin layer 10 at a wavelength of 365 nm and a thickness of 50 μm can be adjusted to a desired value, for example, by appropriately adjusting the types and contents of the components contained in the resin composition that forms the resin layer 10.More specifically, the desired value can be achieved by using an ultraviolet absorber that can absorb light with a wavelength of 365 nm as the ultraviolet absorber (C); adjusting the content of the ultraviolet absorber (C) in the resin composition to an appropriate value; etc.

[0024] The resin layer 10 has a light transmittance of 50% or more at a wavelength of 430 nm and a thickness of 50 μm. The light transmittance of the resin layer 10 at a wavelength of 430 nm and a thickness of 50 μm is preferably 60% or more and 100% or less, more preferably 70% or more and 100% or less, even more preferably 80% or more and 100% or less, even more preferably 90% or more and 100% or less, even more preferably 95% or more and 100% or less, and even more preferably 97% or more and 100% or less.

[0025] The light transmittance of resin layer 10 at a wavelength of 430 nm and a thickness of 50 μm can be adjusted to a desired value, for example, by appropriately adjusting the types and contents of components contained in the resin composition that forms resin layer 10.More specifically, the desired value can be achieved by using a highly transparent resin as resin (A); by ensuring that the resin composition does not contain components that can absorb light with a wavelength of 430 nm; etc.

[0026] The light transmittance of the resin layer 10 at a wavelength of 405 nm and a thickness of 50 μm is preferably 50% or more and 100% or less, more preferably 60% or more and 100% or less, even more preferably 70% or more and 100% or less, and even more preferably 80% or more and 100% or less. It is preferable that the light transmittance of the resin layer 10 at a wavelength of 405 nm and a thickness of 50 μm is within the above range, since the resin layer 10 can be photocured by h-rays (wavelength 405 nm).

[0027] The light transmittance of the resin layer 10 at a wavelength of 850 nm and a thickness of 50 μm is preferably 85% or more and 100% or less, more preferably 90% or more and 100% or less, even more preferably 95% or more and 100% or less, and even more preferably 97% or more and 100% or less, from the viewpoint of further improving the light propagation efficiency of the optical waveguide.

[0028] The light transmittance of the resin layer 10 converted into a value having a thickness of 50 μm means a value calculated by the following method. <Method> A resin film made of a resin composition forming a 50 μm thick resin layer 10 is used as a measurement sample, and the light transmittance is measured using an ultraviolet-visible spectrophotometer while changing the wavelength from 850 nm to 300 nm, and the light transmittance at wavelengths of 365 nm, 405 nm, 430 nm and 850 nm is calculated.

[0029] The method for preparing a measurement sample when calculating the light transmittance converted into a 50 μm thickness of the resin layer 10 is not particularly limited, but an example is a method of obtaining a measurement sample by laminating the resin layer 10 using a laminating machine so that the resin film has a thickness of 50 μm. If the thickness of the resin layer 10 exceeds 50 μm, the measurement sample may be prepared by cutting the resin layer so that the thickness of the resin layer 10 is 50 μm. The method for preparing the measurement sample is preferably the method described in the Examples.

[0030] From the viewpoint of further improving the light propagation efficiency of the optical waveguide, the refractive index of the resin layer 10 is preferably 1.57 or less, more preferably 1.56 or less, and even more preferably 1.55 or less, and the lower limit is not particularly limited, but may be, for example, 1.47 or more, or 1.48 or more. Moreover, from the viewpoint of further improving the light propagation efficiency of the optical waveguide, the refractive index of the resin layer 10 is preferably 1.47 or more and 1.57 or less, more preferably 1.47 or more and 1.56 or less, and even more preferably 1.48 or more and 1.55 or less. The refractive index of the resin layer 10 means a refractive index measured using an Abbe refractometer under the conditions of 23° C. and 589 nm.

[0031] From the viewpoint of further improving the light propagation efficiency of the optical waveguide, the thickness of the resin layer 10 is preferably 1 μm or more and 150 μm or less, more preferably 3 μm or more and 130 μm or less, even more preferably 5 μm or more and 100 μm or less, even more preferably 8 μm or more and 70 μm or less, even more preferably 15 μm or more and 50 μm or less, and even more preferably 20 μm or more and 30 μm or less.

[0032] Hereinafter, each of the components of the resin composition that forms the resin layer 10 will be described.

[0033] <Resin (A)> The resin composition of the present embodiment contains a resin (A). The resin (A) is not particularly limited as long as it is a resin that can be used for the clad of an optical waveguide, and includes, for example, at least one selected from the group consisting of a compound having a cyclic ether structure, a resin having a norbornene structure, a polyimide resin, a silicone resin, and (meth)acrylate, and preferably includes at least one selected from the group consisting of a compound having a cyclic ether structure, a resin having a norbornene structure, and a polyimide resin.

[0034] The resin (A) preferably contains a compound having a cyclic ether structure and a resin having a norbornene structure. In another preferred embodiment, the resin (A) preferably contains a compound having a cyclic ether structure and a polyimide resin.

[0035] From the viewpoint of further improving the light propagation efficiency of the optical waveguide, the refractive index of the resin (A) is preferably 1.57 or less, more preferably 1.56 or less, and even more preferably 1.55 or less, and the lower limit is not particularly limited, but may be, for example, 1.43 or more, or 1.44 or more. Moreover, from the viewpoint of further improving the light propagation efficiency of the optical waveguide, the refractive index of the resin (A) is preferably 1.43 or more and 1.57 or less, more preferably 1.43 or more and 1.56 or less, and even more preferably 1.44 or more and 1.55 or less. The refractive index of the resin (A) means the refractive index measured with an Abbe refractometer under the conditions of 23° C. and 589 nm.

[0036] The resin (A) preferably contains a compound having a cyclic ether structure. The compound having a cyclic ether structure of the present embodiment may be a monomer, oligomer, or polymer in general, and its molecular weight and molecular structure are not particularly limited.

[0037] The compound having a cyclic ether structure of the present embodiment preferably includes at least one selected from the group consisting of epoxy compounds and oxetane compounds.

[0038] The compound having a cyclic ether structure of this embodiment is preferably a compound containing two or more cyclic ether structures in the molecule, and more preferably a compound containing two or three cyclic ether structures in the molecule.

[0039] The compound having a cyclic ether structure of the present embodiment is preferably liquid at 23° C. from the viewpoint of further improving the handleability when producing a resin composition.

[0040] The content of the compound having a cyclic ether structure in the resin composition of this embodiment is preferably 5% by mass or more and 70% by mass or less, more preferably 10% by mass or more and 65% by mass or less, and even more preferably 15% by mass or more and 60% by mass or less, when the total content of non-volatile components in the resin composition is 100% by mass.

[0041] The resin (A) preferably includes a resin having a norbornene structure.

[0042] The resin having a norbornene structure of this embodiment preferably contains a structural unit represented by formula (1).

[0043] [ka]

[0044] In formula (1), R represents a hydrogen atom, a hydroxyl group, or an organic group having 1 to 30 carbon atoms.

[0045] In formula (1), the organic group constituting R is, for example, any 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, and an organic group having a carboxyl group. In formula (1), the organic group constituting R preferably excludes a group having a cyclic ether structure. 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. The alkenyl group may be, for example, at least one selected from the group consisting of an allyl group, a pentenyl group, a vinyl group, and the like. Examples of the alkynyl group include an ethynyl group. The alkylidene group may be, for example, at least one selected from the group consisting of a methylidene group, an ethylidene group, and the like. The aryl group may be, for example, at least one selected from the group consisting of a phenyl group, a naphthyl group, an anthracenyl group, and the like. The aralkyl group may be, for example, at least one selected from the group consisting of a benzyl group, a phenethyl group, and the like. The alkaryl group may be, for example, at least one selected from the group consisting of a tolyl group, a xylyl group, and the like. The cycloalkyl group may be, for example, at least one selected from the group consisting of an adamantyl group, a cyclopentyl group, a cyclohexyl group, a cyclooctyl group, and the like.

[0046] In the organic group constituting R in formula (1), the alkyl group, alkenyl group, alkynyl group, alkylidene group, aryl group, aralkyl group, alkaryl group, cycloalkyl group, and organic group having a carboxyl group may have one or more hydrogen atoms substituted with halogen atoms, such as fluorine, chlorine, bromine, and iodine.

[0047] In formula (1), R is preferably any one selected from the group consisting of a hydrogen atom and an alkyl group, more preferably any one selected from the group consisting of a hydrogen atom and an alkyl group having 1 to 15 carbon atoms, and even more preferably an alkyl group having 4 to 12 carbon atoms. In formula (1), when R is an alkyl group, the coatability of the resin composition can be further improved.

[0048] The content of the structural unit represented by formula (1) in the resin having a norbornene structure of this embodiment is preferably 5 mol % or more and 95 mol % or less, more preferably 20 mol % or more and 90 mol % or less, and even more preferably 40 mol % or more and 85 mol % or less, when the total of all structural units in the resin having a norbornene structure is taken as 100 mol %.

[0049] The resin having a norbornene structure of this embodiment preferably contains a structural unit represented by formula (2).

[0050] [ka]

[0051] In formula (2), X represents a divalent organic group having 1 to 30 carbon atoms, and Y represents a group having a cyclic ether structure.

[0052] In formula (2), the divalent organic group of X having 1 to 30 carbon atoms is preferably a group containing an oxygen atom. In formula (2), the divalent organic group of X having 1 to 30 carbon atoms preferably has 1 to 20 carbon atoms, more preferably 1 to 10 carbon atoms, and even more preferably 1 to 5 carbon atoms.

[0053] In formula (2), the group having a cyclic ether structure represented by Y preferably includes at least one selected from the group consisting of a group containing an epoxy group and a group containing an oxetanyl group.

[0054] The structural unit represented by formula (2) preferably includes a structural unit represented by formula (2-1).

[0055] [ka]

[0056] In formula (2-1), a represents an integer of 0 or more and 3 or less, and b represents an integer of 1 or more and 3 or less. In formula (2-1), a is preferably 1 or 2, and more preferably 1. In formula (2-1), b is preferably 1 or 2, and more preferably 1.

[0057] The content of the structural unit represented by formula (2) in the resin having a norbornene structure of this embodiment is preferably 5 mol % or more and 95 mol % or less, more preferably 10 mol % or more and 80 mol % or less, and even more preferably 15 mol % or more and 60 mol % or less, when the total of all structural units in the resin having a norbornene structure is taken as 100 mol %.

[0058] The resin having a norbornene structure of this embodiment may contain structural units other than the structural units derived from norbornene-based compounds. The other structural unit includes, for example, at least one selected from the group consisting of a structural unit derived from a maleimide-based compound and a structural unit derived from a compound having an ethylenic double bond, and preferably includes a structural unit derived from a maleimide-based compound. The maleimide-based compound includes, for example, at least one selected from the group consisting of maleimide, N-cyclohexylmaleimide, and the like.

[0059] The resin having a norbornene structure of the present embodiment preferably contains a structural unit represented by formula (1) and a structural unit represented by formula (2), and more preferably contains a structural unit represented by formula (1) and a structural unit represented by formula (2-1). In another preferred embodiment, the resin having a norbornene structure of the present embodiment preferably contains a structural unit represented by formula (2) and a structural unit derived from a maleimide compound, and more preferably contains a structural unit represented by formula (2-1) and a structural unit derived from a maleimide compound.

[0060] The weight average molecular weight (Mw) of the resin having a norbornene structure of this embodiment is preferably 5,000 or more and 200,000 or less, more preferably 7,000 or more and 100,000 or less, and even more preferably 8,000 or more and 80,000 or less, from the viewpoint of further improving the performance balance between heat resistance and solubility in organic solvents of the resin composition. The weight average molecular weight (Mw) of a resin having a norbornene structure means a value determined by gel permeation chromatography (GPC) using polystyrene as a standard substance.

[0061] The content of the resin having a norbornene structure in the resin composition of this embodiment is preferably 20% by mass or more and less than 100% by mass, more preferably 30% by mass or more and 95% by mass or less, and even more preferably 40% by mass or more and 90% by mass or less, when the total content of non-volatile components in the resin composition is 100% by mass.

[0062] The resin having a norbornene structure of this embodiment can be produced, for example, by a known method. More specifically, it can be produced by polymerizing monomers capable of forming each structural unit by any method.

[0063] The resin (A) preferably includes a polyimide resin. The polyimide resin of this embodiment is preferably a polyimide resin containing fluorine atoms. The polyimide resin of this embodiment preferably contains an imide ring structure in the molecule.

[0064] The weight average molecular weight (Mw) of the polyimide resin of the present embodiment is preferably 5,000 or more and 200,000 or less, more preferably 10,000 or more and 150,000 or less, and even more preferably 30,000 or more and 130,000 or less, from the viewpoint of further improving the performance balance between heat resistance and solubility in organic solvents of the resin composition. The weight average molecular weight of the polyimide resin can be determined by gel permeation chromatography (GPC) using polystyrene as a standard substance.

[0065] The content of the polyimide resin in the resin composition of this embodiment is preferably 20% by mass or more and 95% by mass or less, more preferably 30% by mass or more and 90% by mass or less, and even more preferably 40% by mass or more and 85% by mass or less, when the total content of non-volatile components in the resin composition is 100% by mass.

[0066] The polyimide resin of this embodiment can be obtained, for example, by (i) first synthesizing a polyamide by reacting (condensation polymerization) a diamine with an acid dianhydride, and then (ii) imidizing the polyamide (ring-closing reaction). Specific reaction conditions can be, for example, known conditions.

[0067] The content of resin (A) in the resin composition of this embodiment is preferably 50% by mass or more and less than 100% by mass, more preferably 70% by mass or more and less than 100% by mass, even more preferably 90% by mass or more and less than 100% by mass, and even more preferably 95% by mass or more and less than 100% by mass, when the total content of non-volatile components in the resin composition is 100% by mass.

[0068] The resin (A) may be a single resin or may contain two or more resins.

[0069] <Curing agent (B)> The resin composition of the present embodiment contains a curing agent (B). The curing agent (B) includes, for example, at least one selected from the group consisting of a thermal polymerization initiator, a photopolymerization initiator, an amine compound, and the like.

[0070] The curing agent (B) preferably contains a photopolymerization initiator, more preferably a photocationic polymerization initiator. The photocationic polymerization initiator includes, for example, at least one selected from the group consisting of sulfonium salt-type polymerization initiators and iodonium salt-type polymerization initiators, preferably a sulfonium salt-type polymerization initiator, and more preferably a triarylsulfonium salt-type polymerization initiator.

[0071] The photopolymerization initiator is preferably a photopolymerization initiator capable of generating active species by h-rays (wavelength 405 nm). Here, when the photopolymerization initiator is a cationic photopolymerization initiator, the active species is a cation, and when the photopolymerization initiator is a radical photopolymerization initiator, the active species is a radical.

[0072] The curing agent (B) preferably contains a thermal polymerization initiator, more preferably a thermal cationic polymerization initiator. The thermal cationic polymerization initiator includes, for example, at least one selected from the group consisting of sulfonium salt type polymerization initiators and iodonium salt type polymerization initiators, and preferably includes a sulfonium salt type polymerization initiator.

[0073] The curing agent (B) may contain both a photopolymerization initiator and a thermal polymerization initiator.

[0074] The content of the curing agent (B) in the resin composition of this embodiment is preferably 0.01% by mass or more and 3.0% by mass or less, more preferably 0.05% by mass or more and 1.0% by mass or less, and even more preferably 0.1% by mass or more and 0.5% by mass or less, when the total content of non-volatile components in the resin composition is 100% by mass.

[0075] The content of the curing agent (B) in the resin composition of this embodiment is preferably 0.01 parts by mass or more and 3.0 parts by mass or less, more preferably 0.05 parts by mass or more and 1.0 parts by mass or less, and even more preferably 0.1 parts by mass or more and 0.5 parts by mass or less, when the content of the resin (A) in the resin composition is 100 parts by mass.

[0076] The curing agent (B) may contain one type of curing agent or two or more types of curing agents.

[0077] <Ultraviolet absorber (C)> The resin composition of the present embodiment contains an ultraviolet absorber (C). The ultraviolet absorber (C) is preferably an ultraviolet absorber capable of absorbing light with a wavelength of 365 nm.

[0078] The ultraviolet absorber (C) preferably contains at least one selected from the group consisting of polyhydric phenol-based ultraviolet absorbers, benzotriazole-based ultraviolet absorbers, and triazine-based ultraviolet absorbers.

[0079] Examples of commercially available polyhydric phenol-based ultraviolet absorbers include at least one selected from the group consisting of Uvinul 3049, Uvinul 3050 (manufactured by BASF), Adeka STAB AO-30, Adeka STAB AO-40, Adeka STAB AO-50, Adeka STAB AO-60, Adeka STAB AO-80, and Adeka STAB AO-330 (manufactured by ADEKA Corporation). Examples of commercially available benzotriazole-based ultraviolet absorbers include Tinuvin P, Tinuvin PS, Tinuvin 99-2, Tinuvin 326, Tinuvin 384-2, Tinuvin 360, Tinuvin 900, Tinuvin 928, Tinuvin 970, and Tinuvin 1130 (manufactured by BASF), Adeka STAB LA-24, Adeka STAB LA-29, Adeka STAB LA-31RG, Adeka STAB LA-32, and Adeka STAB LA-36 (manufactured by ADEKA Corporation), RUVA-93 (manufactured by Otsuka Chemical Co., Ltd.), JF-77, JF-79, JF-83, JF-832, and JF-500 (manufactured by Johoku Chemical Industry Co., Ltd.), and the like. Examples of commercially available triazine-based ultraviolet absorbers include at least one selected from the group consisting of Tinuvin 400, Tinuvin 405, Tinuvin 477, Tinuvin 479 (manufactured by BASF), Adeka STAB AO-20, Adeka STAB LA-46, Adeka STAB LA-F70 (manufactured by ADEKA CORPORATION), KEMISORB102, KEMISORB102L (manufactured by Chemipro Chemical Co., Ltd.), and the like.

[0080] The content of the ultraviolet absorber (C) in the resin composition of this embodiment is preferably 0.01% by mass or more and 3.0% by mass or less, preferably 0.05% by mass or more and 2.0% by mass or less, more preferably 0.1% by mass or more and 1.0% by mass or less, and even more preferably 0.2% by mass or more and 0.5% by mass or less, from the viewpoint of further suppressing the propagation loss of the optical-electrical composite substrate, when the total content of the non-volatile components in the resin composition is taken as 100% by mass.

[0081] The content of the ultraviolet absorber (C) in the resin composition of this embodiment is preferably 0.01 parts by mass or more and 3.0 parts by mass or less, preferably 0.05 parts by mass or more and 2.0 parts by mass or less, more preferably 0.1 parts by mass or more and 1.0 parts by mass or less, and even more preferably 0.2 parts by mass or more and 0.5 parts by mass or less, when the content of the resin (A) in the resin composition is 100 parts by mass, from the viewpoint of further suppressing the propagation loss of the optical-electrical composite substrate.

[0082] The ultraviolet absorber (C) may contain one type of ultraviolet absorber or two or more types of ultraviolet absorbers.

[0083] <Surfactant (D)> The resin composition of the present embodiment preferably further contains a surfactant (D). The surfactant (D) includes, for example, at least one selected from the group consisting of silicone surfactants and fluorine-based surfactants, and preferably includes a silicone surfactant. The surfactant (D) of the present embodiment may be a single surfactant or may contain two or more surfactants.

[0084] The content of surfactant (D) in the resin composition of this embodiment is preferably 0.01 parts by mass or more and 3.0 parts by mass or less, more preferably 0.05 parts by mass or more and 1.0 parts by mass or less, and even more preferably 0.1 parts by mass or more and 0.5 parts by mass or less, when the content of resin (A) in the resin composition is 100 parts by mass.

[0085] <Other ingredients> The resin composition of the present embodiment may further contain, for example, a curing aid, a leveling agent, a colorant, a storage stabilizer, a plasticizer, a filler, inorganic particles, an antidegradant, a wettability improver, an antistatic agent, etc. The content of other components is an appropriate amount.

[0086] The total content of the resin (A), curing agent (B), and ultraviolet absorber (C) in the resin composition of this embodiment is preferably 80% by mass or more and 100% by mass or less, more preferably 90% by mass or more and 100% by mass or less, and even more preferably 95% by mass or more and 100% by mass or less, from the viewpoint of further suppressing the propagation loss of the optical-electrical composite substrate, when the total content of the non-volatile components in the resin composition of this embodiment is taken as 100% by mass.

[0087] <Base film> The dry film 100 preferably further includes a base film 20 on which a resin layer is formed. The base film 20 may be, for example, a resin film. The resin constituting the base film 20 is not particularly limited, but preferably contains at least one selected from the group consisting of polyethylene terephthalate and polyimide, and more preferably contains polyethylene terephthalate.

[0088] From the viewpoint of further improving the handleability of the film, the thickness of the base film 20 is preferably 10 μm or more and 100 μm or less, more preferably 15 μm or more and 80 μm or less, even more preferably 20 μm or more and 60 μm or less, and even more preferably 25 μm or more and 50 μm or less.

[0089] <Other layers> The dry film 100 may further include other layers. The dry film 100 may further include a cover film. The cover film is preferably provided so as to be in direct contact with the resin layer 10. When the dry film 100 includes the base film 20, the cover film is preferably provided on the surface of the resin layer 10 opposite to the base film 20. The cover film is not particularly limited, but for example, an OPP cover film can be used.

[0090] [Dry film applications] The dry film 100 is a dry film that can be used for an optical waveguide clad. The dry film 100 may be a dry film that can be used for the first clad layer 40 in Fig. 2 or a dry film that can be used for the second clad layer 60 in Fig. 2, but is preferably a dry film that can be used for the first clad layer 40 in Fig. 2. In other words, the dry film 100 is preferably a dry film that can be used for a clad layer provided on a substrate.

[0091] [Dry film manufacturing method] The dry film of this embodiment can be obtained, for example, by mixing the resin composition of this embodiment with an organic solvent to prepare a varnish, applying the varnish to a substrate film, and drying the varnish. Examples of the application method include direct application using various coater devices such as a pin coater, a die coater, a comma coater, and a curtain coater, and printing methods such as screen printing.

[0092] [Resin composition] The resin composition of this embodiment is a resin composition that can be used for optical waveguide cladding, and contains a resin (A), a curing agent (B), and an ultraviolet absorber (C). A resin film formed from the resin composition has a light transmittance of 50% or less at a wavelength of 365 nm and a thickness of 50 μm, and a resin film formed from the resin composition has a light transmittance of 50% or more at a wavelength of 430 nm and a thickness of 50 μm.

[0093] The light transmittance of a resin film formed from a resin composition in terms of a thickness of 50 μm means a value calculated by the following method. <Method> A resin film formed from the resin composition with a thickness of 50 μm is used as a measurement sample, and the light transmittance is measured using an ultraviolet-visible spectrophotometer while changing the wavelength from 850 nm to 300 nm, and the light transmittance at wavelengths of 365 nm, 405 nm, 430 nm, and 850 nm is calculated.

[0094] The method for preparing a measurement sample when calculating the light transmittance of a resin film formed from the resin composition converted into a thickness of 50 μm is not particularly limited, and for example, a method can be used in which a measurement sample is obtained by laminating a film-like resin composition using a laminating machine so that the thickness of the resin film is 50 μm. When the thickness of the film-like resin composition exceeds 50 μm, the measurement sample may be prepared by cutting the resin layer so that the thickness of the film-like resin composition is 50 μm. When the resin composition is in the form of a varnish, for example, the resin composition may be applied to a substrate film and dried to prepare a film of the resin composition, and then a measurement sample may be prepared by the above-mentioned method. The method for preparing the measurement sample is preferably the method described in the Examples.

[0095] In the resin composition of this embodiment, the preferred numerical range of the light transmittance of the resin film formed from the resin composition, converted to a thickness of 50 μm, is the same as the preferred numerical range of the light transmittance of the resin layer 10 in the dry film 100, converted to a thickness of 50 μm.

[0096] The preferred physical properties and applications of the resin composition of this embodiment are the same as the preferred physical properties and applications of the resin layer 10 in the dry film 100 . When the resin composition of the present embodiment is in the form of a varnish, the physical property values ​​of the resin composition of the present embodiment can be obtained by preparing a resin film from the resin composition and then measuring the properties in the same manner as for the resin layer 10. The resin film formed from the resin composition can be prepared, for example, by applying the resin composition to a substrate film and drying it.

[0097] The aspects of the components of the resin composition of this embodiment are the same as the aspects of the components of the resin composition that forms the resin layer 10 of the dry film 100 .

[0098] The resin composition of the present embodiment may contain an organic solvent. When the resin composition of the present embodiment contains an organic solvent, it can be made into a varnish-like resin composition.

[0099] The organic solvent of the present embodiment includes at least one selected from the group consisting of, for example, 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, and butyl lactate. The organic solvent of the present embodiment may be a single organic solvent, or may contain two or more organic solvents.

[0100] When the resin composition of the present embodiment contains an organic solvent, the concentration of the total solids (non-volatile components) in the resin composition is preferably 10% by mass or more and 60% by mass or less, more preferably 20% by mass or more and 55% by mass or less, and even more preferably 30% by mass or more and 50% by mass or less, from the viewpoint of appropriately controlling the viscosity of the resin composition and sufficiently dissolving each component in the resin composition.

[0101] [Optical waveguide] The optical waveguide of this embodiment will be described with reference to FIG. The optical waveguide 200 is an optical waveguide 200 in which a first clad layer 40, a core layer 50, and a second clad layer 60 are laminated in this order, and at least one of the first clad layer 40 and the second clad layer 60 is a layer formed by curing the resin layer 10 in the dry film 100. In this specification, when the optical waveguide 200 is provided on the substrate 30, the cladding layer located on the substrate 30 side is referred to as the first cladding layer 40. Furthermore, hereinafter, when simply referring to a "cladding layer," this concept includes both the first cladding layer 40 and the second cladding layer 60.

[0102] In the optical waveguide 200, the first clad layer 40 is preferably a layer formed by curing the resin layer 10 in the dry film 100.

[0103] From the viewpoint of further improving the optical propagation efficiency of the optical waveguide, the thickness of the first cladding layer 40 is preferably 1 μm or more and 150 μm or less, more preferably 3 μm or more and 100 μm or less, even more preferably 5 μm or more and 70 μm or less, even more preferably 8 μm or more and 50 μm or less, even more preferably 10 μm or more and 40 μm or less, even more preferably 15 μm or more and 30 μm or less, and even more preferably 20 μm or more and 30 μm or less.

[0104] From the viewpoint of further suppressing thermal deformation of the optical waveguide, the thickness of the second cladding layer 60 is preferably 1 μm or more and 150 μm or less, more preferably 3 μm or more and 100 μm or less, even more preferably 5 μm or more and 70 μm or less, even more preferably 8 μm or more and 50 μm or less, and even more preferably 8 μm or more and 20 μm or less.

[0105] The material for forming the core layer 50 is not particularly limited, but may be formed from, for example, a resin composition. The resin for forming the core layer 50 includes, for example, a resin used for the core of a known optical waveguide, preferably a cyclic olefin resin, and more preferably a norbornene resin. The resin composition for forming the core layer 50 may contain an antioxidant, a photopolymerization initiator, etc. The photopolymerization initiator contained in the resin composition for forming the core layer 50 is preferably a photopolymerization initiator that can generate active species by i-rays (wavelength 365 nm).

[0106] The thickness of the core layer 50 is preferably 1 μm or more and 100 μm or less, more preferably 5 μm or more and 80 μm or less, even more preferably 10 μm or more and 60 μm or less, and even more preferably 30 μm or more and 50 μm or less.

[0107] A waveguide pattern may be formed in the core layer 50. Methods for forming the waveguide pattern include, for example, exposure, etching, and replication, with exposure being preferred.

[0108] A mirror may be formed on the optical waveguide 200, and a mirror on the light-emitting element side and a mirror on the light-receiving element side may be formed. The mirrors may be formed, for example, by forming an inclined surface by laser processing or the like.

[0109] The optical waveguide 200 may include other layers in addition to the first cladding layer 40, the core layer 50, and the second cladding layer 60, as long as the excellent performance of the optical waveguide 200 is not affected.

[0110] [Optical / electrical composite substrate] The optical and electrical composite substrate of this embodiment will be described with reference to FIG. The optical / electrical composite substrate 300 includes a substrate 30 and an optical waveguide 200 provided on the substrate 30 .

[0111] The substrate 30 may be, for example, a printed circuit board or a flexible substrate, and is preferably a flexible substrate. The substrate 30 is preferably a double-sided copper-clad laminate. The substrate 30 may have vias formed therein.

[0112] The optical / electrical composite substrate 300 may further include a polyimide substrate (not shown) on the surface of the second cladding layer 60 opposite to the core layer 50 side.

[0113] The optical / electrical composite substrate 300 may include a light emitting element, a light receiving element, and the like.

[0114] The optical-electrical composite substrate 300 can be obtained, for example, by (i) forming a first clad layer 40 on the substrate 30, (ii) forming a core layer 50 on the first clad layer 40, and (iii) forming a second clad layer 60 on the core layer 50. Examples of methods for forming each layer include methods in which films for forming each layer are laminated in order by roll lamination, vacuum roll lamination, flat plate lamination, vacuum flat plate lamination, atmospheric pressing, vacuum pressing, etc.

[0115] [Electronic Components] The electronic component of this embodiment includes the optical / electrical composite substrate of this embodiment. Examples of the electronic component of this embodiment include electronic components in electronic devices such as mobile phones, game machines, router devices, WDM devices, personal computers, televisions, and home servers.

[0116] 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]

[0117] 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.

[0118] [Raw materials] First, the raw materials used in the examples and comparative examples will be described.

[0119] <Resin synthesis> (Synthesis of Resin (A-1) Having a Norbornene Structure) A reaction vessel equipped with a stirrer and a condenser was prepared. The inside of the vessel was first thoroughly purged with nitrogen. Then, 124.8 g (0.7 mol) of n-hexylnorbornene, 54.1 g (0.3 mol) of 2-[(bicyclo[2.2.1]hept-5-en-2-ylmethoxy)methyl]oxirane, and 440 g of toluene were charged and heated to 50 °C in an oil bath while stirring. A solution of 29.9 g (0.02 mol) of (toluene)Ni(CF) in 5 g of toluene was added, and the reaction was continued for 3 hours at 50 °C. The resulting solution was reprecipitated in a large amount of methanol to obtain a polymer precipitate, which was then filtered using a suction filter to obtain a polymer powder. The resulting polymer was then vacuum dried at 60 °C for 16 hours to obtain Resin (A-1) having a norbornene structure. The weight average molecular weight (Mw) of the resin (A-1) having a norbornene structure measured by GPC was 50,000, and the refractive index of the resin (A-1) having a norbornene structure measured by an Abbe refractometer at 23°C and 589 nm was 1.51.

[0120] (Synthesis of Resin (A-2) Having a Norbornene Structure) A reaction vessel equipped with a stirrer and a condenser was prepared. The inside of the vessel was first thoroughly purged with nitrogen. Then, 164.1 g (0.7 mol) of n-decylnorbornene, 54.1 g (0.3 mol) of 2-[(bicyclo[2.2.1]hept-5-en-2-ylmethoxy)methyl]oxirane, and 530 g of toluene were charged and heated to 50 °C in an oil bath while stirring. A solution of 29.9 g (0.02 mol) of (toluene)Ni(CF) in 5 g of toluene was added, and the reaction was continued for 3 hours at 50 °C. The resulting solution was reprecipitated in a large amount of methanol to obtain a polymer precipitate, which was then filtered using a suction filter to obtain a polymer powder. The resulting polymer was then dried in vacuum at 60 °C for 16 hours to obtain a resin (A-2) having a norbornene structure. The weight average molecular weight (Mw) of the resin (A-2) having a norbornene structure measured by GPC was 52,000, and the refractive index of the resin (A-2) having a norbornene structure measured by an Abbe refractometer at 23°C and 589 nm was 1.51.

[0121] (Synthesis of Resin (A-3) Having a Norbornene Structure) 90 g (0.5 mol) of 2-[(bicyclo[2.2.1]hept-5-en-2-ylmethoxy)methyl]oxirane, 24.3 g (0.25 mol) of maleimide, 44.8 g (0.25 mol) of N-cyclohexylmaleimide, and 2.3 g (0.01 mol) of dimethyl 2,2'-azobis(2-methylpropionate) were weighed into an appropriately sized reaction vessel equipped with a stirrer and a condenser, and dissolved in 263 g of methyl ethyl ketone and 113 g of toluene. Dissolved oxygen was removed from the system by nitrogen bubbling, and the vessel was sealed and reacted at 70 °C for 16 hours. The resulting solution was cooled to room temperature and then reprecipitated in a large amount of heptane to obtain a polymer precipitate. Subsequently, the polymer was filtered off using a suction filter, and the powder was washed with heptane and then dried in a dryer at 60° C. for 24 hours to obtain a resin (A-3) having a norbornene structure. The weight average molecular weight (Mw) of the resin (A-3) having a norbornene structure measured by GPC was 8,500, and the refractive index of the resin (A-3) having a norbornene structure measured by an Abbe refractometer at 23°C and 589 nm was 1.51.

[0122] (Synthesis of Polyimide Resin (A-4)) A 3-liter separable glass flask equipped with a stirrer and a stirring blade was charged with 67.3 g (0.21 mol) of 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl, 97.7 g (0.22 mol) of 4,4'-(hexafluoroisopropylidene)diphthalic dianhydride, and 495 g of dimethylacetamide, and the mixture was stirred to dissolve. The mixture was further stirred at room temperature under a nitrogen stream for 12 hours to carry out the polymerization reaction, yielding a polyamic acid solution.

[0123] 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.

[0124] 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 in a vacuum dryer at 100°C for 24 hours and then at 200°C for 3 hours to obtain polyimide resin (A-4). The weight average molecular weight (Mw) of polyimide resin (A-4) measured by GPC was 51,000, and the refractive index of polyimide resin (A-4) measured by an Abbe refractometer at 23° C. and 589 nm was 1.54.

[0125] The details of the ingredients for each component in Tables 1 and 2 are as follows:

[0126] <Resin (A)> <Resin having a norbornene structure> (A-1) Resin having a norbornene structure synthesized above (A-2) Resin having a norbornene structure synthesized above (A-3) Resin having a norbornene structure synthesized above <Polyimide resin> (A-4) Polyimide resin synthesized above <Compounds with a cyclic ether structure> (A-5) JER-YX8000 (manufactured by Mitsubishi Chemical Corporation, epoxy compound, liquid at 23°C, refractive index 1.51) (A-6) Denacol EX-321L (manufactured by Nagase ChemteX Corporation, epoxy compound, liquid at 23°C, refractive index 1.50) (A-7) Aron Oxetane OXT-221 (manufactured by Toagosei Co., Ltd., oxetane compound, liquid at 23°C, refractive index 1.45) (A-8) Celloxide 2021P (manufactured by Daicel Corporation, epoxy compound, liquid at 23°C, refractive index 1.51)

[0127] [ka]

[0128] [ka]

[0129] <Curing agent (B)> (B-1) CPI-410B (San-Apro Co., Ltd., photocationic polymerization initiator) (B-2) San-Aid SI-B5 (manufactured by Sanshin Chemical Industry Co., Ltd., thermal cationic polymerization initiator)

[0130] <Ultraviolet absorber (C)> (C-1) Uvinul 3050 (BASF, polyphenol-based ultraviolet absorber) (C-2) Tinuvin 384-2 (BASF, benzotriazole-based UV absorber) (C-3) Tinuvin 477 (BASF, hydroxyphenyltriazine UV absorber)

[0131] <Surfactant (D)> (D-1) BYK-333 (BYK Japan Co., Ltd., silicone surfactant)

[0132] <Organic solvent (E)> (E-1) Toluene (E-2) Propylene glycol monomethyl ether-2-acetate

[0133] [Examples 1 to 18 and Comparative Examples 1 and 2] (Preparation of Resin Composition) The raw materials formulated according to Tables 1 and 2 were stirred at room temperature until the raw materials were completely dissolved to obtain a solution, which was then filtered through a PTFE filter with a pore size of 0.2 μm to obtain varnish-like resin compositions of Examples 1 to 18 and Comparative Examples 1 and 2, respectively.

[0134] (Preparation of dry film for forming first clad layer) The resin compositions of Examples 1 to 18 and Comparative Examples 1 to 2 obtained by preparing the above resin compositions were applied as a varnish using an applicator onto a 38 μm thick antistatic treated polyethylene terephthalate substrate so that the thickness after drying would be the resin layer thickness shown in Tables 1 and 2.Then, the substrate was dried at 100°C for 10 minutes, and finally, an OPP cover film was attached to the surface of the resin layer formed by the resin composition to create a film, thereby obtaining the dry films of Examples 1 to 18 and Comparative Examples 1 to 2, respectively.

[0135] (Preparation of dry film for core layer formation) (Synthesis of polymer for forming core layer) In a glove box filled with dry nitrogen and with moisture and oxygen concentrations both controlled to 1 ppm or less, 7.2 g (40.1 mmol) of hexylnorbornene (HxNB) and 12.9 g (40.1 mmol) of diphenylmethylnorbornene methoxysilane were weighed into a 500 mL vial, to which 60 g of dehydrated toluene and 11 g of ethyl acetate were added, and the vial was then 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, the vial was sealed with a stirrer tip, and the Ni catalyst was thoroughly stirred to completely dissolve, yielding a Ni catalyst solution. 1 mL of the Ni catalyst solution was accurately measured with a syringe and quantitatively injected into the vial containing the two norbornenes dissolved above. Stirring was continued at room temperature for 1 hour, resulting in a significant increase in viscosity. At this point, the stopper was removed, and 60 g of tetrahydrofuran (THF) was added and stirred to obtain a reaction solution. A 100 mL beaker was charged with 9.5 g of acetic anhydride, 18 g of hydrogen peroxide (30% concentration), and 30 g of ion-exchanged water, and the resulting mixture was stirred to prepare an aqueous solution of peracetic acid. The entire amount of the aqueous solution of peracetic acid was then added to the reaction solution and stirred for 12 hours to reduce Ni. Next, the reaction solution was transferred to a separatory funnel, and after removing the lower aqueous layer, 100 mL of a 30% aqueous solution of isopropyl alcohol was added and vigorously stirred. After allowing the mixture to stand and completely separate into two layers, the aqueous layer was removed. This water washing process was repeated three times, and the oil layer was then dropped into a large excess of acetone to reprecipitate the resulting polymer. The filtrate was separated by filtration and then heated and dried for 12 hours in a vacuum dryer set at 60°C to obtain the core layer-forming polymer. The weight-average molecular weight of the resulting polymer measured by GPC was 100,000.

[0136] (Preparation of Resin Composition for Forming Core Layer) 10 g of the purified core layer-forming polymer was weighed into a 100 mL glass container, and 30 g of toluene, 2.4 g of an oxetane compound (manufactured by Toagosei Co., Ltd., product name: OXT-213), 0.8 g of an epoxy compound having an alicyclic structure (manufactured by Daicel Corporation, product name: CELLOXIDE 2021P), 0.03 g of a photocationic polymerization initiator (manufactured by San-Apro Co., Ltd., product name: CPI-310B), and 0.1 g of an antioxidant (manufactured by BASF, product name: Irganox1076) were added thereto and dissolved uniformly. The mixture was then filtered through a 0.2 μm PTFE filter to obtain a core layer-forming resin composition.

[0137] (Preparation of dry film for core layer formation) The obtained core layer-forming resin composition was applied to a release-treated PET film using an applicator so that the film thickness after drying would be 40 μm. After coating, the film was placed in a dryer at 45°C for 5 minutes to completely remove the solvent, forming a coating. Finally, an OPP cover film was attached to the surface of the resin layer formed by the resin composition, thereby producing a dry film for forming a core layer.

[0138] (Preparation of dry film for forming second cladding layer) (Preparation of Resin Composition for Forming Second Clad Layer) 8.0 g of a resin (A-1) having a norbornene structure, 2.0 g of JER-YX8000 (A-5), 0.03 g of BYK-333 (D-1), and 0.5 g of Curesol C11z (an imidazole compound manufactured by Shikoku Kasei Co., Ltd.) were weighed out, and 30 g of toluene was added to completely dissolve the mixture. The mixture was then filtered through a 0.2 μm PTFE filter to obtain a resin composition for forming a second cladding layer. (Preparation of dry film for forming second cladding layer) The obtained resin composition for forming the second cladding layer was applied as a varnish using an applicator onto a 25 μm thick polyimide substrate so that the dried thickness would be 10 μm, and then dried at 100°C for 10 minutes.Finally, an OPP cover film was attached to the surface of the resin layer formed by the resin composition to create a film, and a dry film for forming the second cladding layer was obtained.

[0139] The light transmittance of the dry film for forming a second cladding layer at a wavelength of 365 nm and a thickness of 50 μm was greater than 50%. Here, the light transmittance of the dry film for forming a second cladding layer at a wavelength of 365 nm means a value obtained by a method similar to that used to measure the light transmittance of each example and comparative example.

[0140] (Fabrication of photoelectric composite substrate) (Preparation of scratched double-sided copper clad laminate) Ten 70 mm long scratches were made at 5 mm intervals on a double-sided copper-clad laminate measuring 80 mm wide, 120 mm long and 50 μm thick using a marking rod, so that the scratches were perpendicular to the length of the double-sided copper-clad laminate (so that the scratches were perpendicular to the waveguide pattern (line and space) described below), to produce a scratched double-sided copper-clad laminate. (Fabrication of photoelectric composite substrate) The scratched double-sided copper-clad laminate prepared above was placed on a stainless steel plate. After peeling off the OPP cover film of the dry film for forming the first clad layer, the resin layer for forming the clad layer of the dry film for forming the first clad layer was laminated to the scratched double-sided copper-clad laminate using a vacuum laminator (manufactured by Nikko Materials Co., Ltd., device name: CVP-600) under conditions of temperature: 140°C, pressure: 5.0 MPa, and time: 120 seconds. Then, a high-pressure mercury lamp was used to expose the entire film for forming the first clad layer to a dose of 1000 mJ / cm. 2 The laminate was then exposed to light under these conditions, and then heated in an atmospheric oven at 160°C for 1 hour. The light from the high-pressure mercury lamp was a mixture of i-line (365nm), h-line (405nm), g-line (436nm), etc. Laminate A was obtained, with a layer structure of "scratched double-sided copper-clad laminate / first clad layer / PET substrate." The PET substrate here was derived from the dry film used to form the first clad layer.

[0141] Next, the PET substrate of Laminate A was peeled off, and the OPP cover film of the dry film for core layer formation was peeled off. The first cladding layer in Laminate A was then bonded to the resin layer for forming the core layer of the dry film for core layer formation using a vacuum laminator (Nikko Materials Co., Ltd., product name: CVP-300) at a temperature of 60°C, a pressure of 0.5 MPa, and a time of 30 seconds. Next, a direct imaging exposure machine (SCREEN Co., Ltd., product name: LI-9000) was used to create 20 lines and spaces 9 cm long, with an exposed area of ​​10 μm and an unexposed area of ​​50 μm. The resin layer for forming the core layer was exposed to light with a wavelength of 365 nm. Thereafter, the PET substrate derived from the dry film for forming the core layer was peeled off, and the resultant was heated in an atmospheric oven at 120°C for 1 hour to obtain Laminate B having a layer structure of "scratched double-sided copper-clad laminate / first clad layer / core layer."

[0142] Next, the OPP cover film of the dry film for forming the second cladding layer was peeled off, and the core layer in Laminate B was laminated to the resin layer (a resin layer composed of the resin composition for forming the cladding layer) in the dry film for forming the second cladding layer using a vacuum laminator (manufactured by Nikko Materials Co., Ltd., model CVP-300) at a temperature of 140°C, a pressure of 0.5 MPa, and a time of 120 seconds, followed by heating in an atmospheric oven at 160°C for 2 hours to obtain the optoelectronic composite substrates of Examples 1 to 18 and Comparative Examples 1 and 2. The layer structure of the optoelectronic composite substrates was "scratched double-sided copper-clad laminate / first cladding layer / core layer / second cladding layer / polyimide substrate."

[0143] [evaluation] The evaluation methods for the examples and comparative examples are described below.

[0144] <Coatability evaluation> The appearance of the dry films of Examples 1 to 18 and Comparative Examples 1 and 2 was observed, and samples that had no appearance abnormalities such as standard B were rated as A, and samples that had appearance abnormalities (uneven coating, cloudiness, repelling, cracks, etc.) were rated as B.

[0145] <Refractive index> The OPP cover film was peeled off from the dry films of Examples 1 to 18 and Comparative Examples 1 and 2, and the refractive index was measured using an Abbe refractometer (manufactured by Atago Co., Ltd., product name: NAR-1T SOLID) under conditions of 23°C and 589 nm.

[0146] <Light transmittance> The OPP cover film was peeled off from the dry films of Examples 1 to 18 and Comparative Examples 1 and 2. The resin layer formed from the resin composition was then laminated onto a glass slide at a temperature of 140°C, a pressure of 0.5 MPa, and a time of 2 minutes, with the resin layer facing the glass slide. The substrate film was then peeled off, and the film was deposited on the glass slide. This process was repeated twice to obtain a transmittance measurement sample (glass slide with resin composition) with a 50 μm-thick resin layer formed from the resin composition. Next, a 100% calibration was performed using a UV-Vis spectrophotometer (manufactured by JASCO Corporation, product name: V-670) with glass slides inserted into both the background slot and the sample slot. The glass slide next to the measurement slot was replaced with the transmittance measurement sample, and the light transmittance (%) was measured in transmittance measurement mode while varying the wavelength from 850 nm to 300 nm. The light transmittance (%) at wavelengths of 365 nm, 405 nm, 430 nm, and 850 nm was then read from the results.

[0147] <Optical loss evaluation> The optoelectronic composite substrates of Examples 1 to 18 and Comparative Examples 1 and 2 were cut by dicing on both sides so that the length of the patterned portion was 7 cm, to obtain samples for evaluating optical loss. The samples for evaluating optical loss were designed to include all 10 scratches on the double-sided copper-clad laminate. The propagation loss of the optical loss evaluation sample was evaluated in accordance with 4.6.2.1 Cutback Method of "Test Method for Polymer Optical Waveguides (JPCA-PE02-05-01S-2008)." Note that light with a wavelength of 850 nm was used for the measurement. The measurement was repeated 20 times, and the average value of the propagation loss was evaluated as the average propagation loss [dB], and the difference between the maximum and minimum propagation losses was evaluated as the propagation loss variation [dB]. From the results obtained, samples with an average propagation loss of less than 1 dB were evaluated as A, samples with an average propagation loss of 1 dB to 3 dB as B, and samples with an average propagation loss of more than 3 dB as C. Additionally, samples with a propagation loss variation of less than 0.3 dB were evaluated as A, samples with a propagation loss variation of 0.3 dB to 0.5 dB as B, and samples with a propagation loss variation of more than 0.5 dB as C.

[0148] The evaluation results for each example and each comparative example are shown in Tables 1 and 2, respectively.

[0149] [Table 1]

[0150] [Table 2]

[0151] As can be seen from Tables 1 and 2, the optical and electrical composite substrates of the examples had better optical loss evaluation results than the optical and electrical composite substrates of the comparative examples. That is, it can be seen that the dry film and resin composition of the present embodiment can suppress the propagation loss of the optical and electrical composite substrate. [Explanation of symbols]

[0152] 10 Resin layer 20 Base film 30 boards 40 First cladding layer 50 Core Layer 60 Second cladding layer 100 dry film 200 Optical waveguide 300 Optical and electrical composite substrate

Claims

1. A dry film that can be used for an optical waveguide clad, a resin layer formed from a resin composition; The resin composition includes a resin (A), a curing agent (B), and an ultraviolet absorber (C), the resin layer has a light transmittance of 50% or less at a wavelength of 365 nm and a thickness of 50 μm; The resin layer has a light transmittance of 50% or more at a wavelength of 430 nm and a thickness of 50 μm.

2. 2. The dry film according to claim 1, wherein the ultraviolet absorber (C) comprises at least one selected from the group consisting of polyhydric phenol-based ultraviolet absorbers, benzotriazole-based ultraviolet absorbers, and triazine-based ultraviolet absorbers.

3. 3. The dry film according to claim 1, wherein the content of the ultraviolet absorber (C) in the resin composition is 0.01 mass% or more and 3.0 mass% or less when the total content of non-volatile components in the resin composition is 100 mass%.

4. The dry film according to claim 1 or 2, wherein the curing agent (B) contains a photopolymerization initiator.

5. The dry film according to claim 4 , wherein the photopolymerization initiator includes a cationic photopolymerization initiator.

6. The dry film according to claim 1 or 2, wherein the curing agent (B) contains a thermal polymerization initiator.

7. The dry film according to claim 6 , wherein the thermal polymerization initiator comprises a thermal cationic polymerization initiator.

8. 3. The dry film according to claim 1, wherein the content of the curing agent (B) in the resin composition is 0.01% by mass or more and 3.0% by mass or less when the total content of non-volatile components in the resin composition is 100% by mass.

9. The dry film according to claim 1 or 2, wherein the resin (A) contains a compound having a cyclic ether structure.

10. The dry film according to claim 9 , wherein the compound having a cyclic ether structure includes at least one selected from the group consisting of an epoxy compound and an oxetane compound.

11. The dry film according to claim 9, wherein the content of the compound having a cyclic ether structure in the resin composition is 5% by mass or more and 70% by mass or less when the total content of non-volatile components in the resin composition is 100% by mass.

12. The dry film according to claim 1 or 2, wherein the resin (A) includes a resin having a norbornene structure.

13. The dry film according to claim 12 , wherein the resin having a norbornene structure contains a structural unit represented by the following formula (1): [Chemical 1] (In the formula (1), R represents a hydrogen atom, a hydroxyl group, or an organic group having 1 to 30 carbon atoms.)

14. 14. The dry film according to claim 13, wherein the content of the structural unit represented by formula (1) in the resin having a norbornene structure is 5 mol % or more and 95 mol % or less, when the total of all structural units in the resin having a norbornene structure is 100 mol %.

15. The dry film according to claim 12 , wherein the resin having a norbornene structure contains a structural unit represented by the following formula (2): 【Chemistry 2】 (In the formula (2), X represents a divalent organic group having 1 to 30 carbon atoms, and Y represents a group having a cyclic ether structure.)

16. The dry film according to claim 12, wherein the content of the resin having a norbornene structure in the resin composition is 20% by mass or more when the total content of non-volatile components in the resin composition is 100% by mass.

17. The dry film according to claim 1 or 2, wherein the resin (A) includes a polyimide resin.

18. The dry film according to claim 1 or 2, wherein the refractive index of the resin layer is 1.47 or more and 1.57 or less.

19. The dry film according to claim 1 or 2, wherein the resin layer has a thickness of 1 μm or more and 150 μm or less.

20. 3. The dry film according to claim 1, wherein the resin layer has a light transmittance of 85% or more at a wavelength of 850 nm and a thickness of 50 μm.

21. Further, a base film is provided, The dry film according to claim 1 , further comprising the resin layer on the substrate film.

22. The dry film according to claim 21 , wherein the resin constituting the base film includes at least one selected from the group consisting of polyethylene terephthalate and polyimide.

23. A resin composition that can be used for an optical waveguide clad, A composition comprising a resin (A), a curing agent (B), and an ultraviolet absorber (C), a resin film formed from the resin composition has a light transmittance of 50% or less at a wavelength of 365 nm and a thickness of 50 μm; A resin composition, wherein a resin film formed from the resin composition has a light transmittance of 50% or more at a wavelength of 430 nm and a thickness of 50 μm.

24. An optical waveguide in which a first clad layer, a core layer, and a second clad layer are laminated in this order, 3. An optical waveguide, wherein at least one of the first clad layer and the second clad layer is a layer formed by curing the resin layer in the dry film according to claim 1.

25. A substrate; An optical / electrical composite substrate comprising: the optical waveguide according to claim 24 provided on the substrate.

26. An electronic component comprising the optical-electrical composite substrate according to claim 25.

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