Resin composition for optical waveguide, dry film for optical waveguide, and optical waveguide

Abstract

To provide a resin composition for an optical waveguide which suppresses white turbidness and yellow discoloration, and can improve transparency.SOLUTION: A resin composition for an optical waveguide contains a (meth)acrylate resin (A), an epoxy resin (B), and a photopolymerization initiator (C). The (meth)acrylate resin (A) contains an alicyclic (meth)acrylate compound (A-1), an aromatic (meth)acrylate compound (A-2) and / or a (meth)acrylate monomer (A-3). The alicyclic (meth)acrylate compound (A-1) has a non-aromatic carbon ring in the side chain. The aromatic (meth)acrylate compound (A-2) has at least two hydroxy groups in one molecule. The photopolymerization initiator (C) has an absorption coefficient to light at the wavelength of 405 nm of 500 mL / (g cm) or less.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present disclosure relates to a resin composition for an optical waveguide, a dry film for an optical waveguide, and an optical waveguide. [Background technology]

[0002] In the field of medium-distance communications such as FTTH (Fiber To The Home) and in-vehicle communications, optical fiber cables are used as a transmission medium, but in the field of short-distance communications, high-density wiring (narrow pitch, branching, crossing, multi-layering, etc.) is required, which is difficult to achieve with optical fiber cables. Therefore, optical wiring boards equipped with optical waveguides that can meet the above conditions, and optical / electrical composite wiring boards equipped with electrical circuits, are being considered.

[0003] The optical waveguide may be, for example, a polymer optical waveguide made of a resin material. As the optical waveguide provided in the optoelectronic composite wiring board, a polymer optical waveguide is preferable in view of compatibility with a wiring board provided with an electric circuit.

[0004] One of the processes for forming a polymer optical waveguide is a development process, and one of the development methods is alkaline development, which uses an alkaline aqueous solution as a developer. Alkaline development is a method of developing by dissolving an uncured resin composition that is not necessary for forming an optical waveguide in an alkaline solution.

[0005] Examples of materials for such optical waveguides include a resin composition for molding optical waveguides, which uses a resin containing (A) a polymer having a carboxyl group, (B) a (meth)acrylate, (C) a photoradical polymerization initiator, and (D) a phenol-based antioxidant, as described in Patent Document 1. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent No. 5771978 Summary of the Invention [Problem to be solved by the invention]

[0007] Incidentally, high transparency is required for the core and clad of an optical waveguide. Therefore, the resin composition and dry film used are required to have excellent transparency. However, depending on the combination of resins and the selection of photopolymerization initiator, they may become cloudy or turn yellow.

[0008] An object of the present disclosure is to provide a resin composition for an optical waveguide, a dry film for an optical waveguide, and an optical waveguide that can suppress turbidity and yellowing and enhance transparency. [Means for solving the problem]

[0009] The resin composition for optical waveguide according to one embodiment of the present disclosure contains a (meth)acrylate resin (A), an epoxy resin (B), and a photopolymerization initiator (C). The (meth)acrylate resin (A) contains an alicyclic (meth)acrylate compound (A-1), an aromatic (meth)acrylate compound (A-2) and / or a (meth)acrylate monomer (A-3). The alicyclic (meth)acrylate compound (A-1) has a non-aromatic carbon ring in a side chain. The aromatic (meth)acrylate compound (A-2) has at least two hydroxyl groups in one molecule. The photopolymerization initiator (C) has an absorption coefficient of 500 mL / (g cm) or less for light having a wavelength of 405 nm.

[0010] A dry film for an optical waveguide according to one embodiment of the present disclosure includes a resin layer containing the resin composition for an optical waveguide or a semi-cured product of the resin composition for an optical waveguide.

[0011] An optical waveguide according to an aspect of the present disclosure includes a core portion and a clad layer covering the core portion, wherein at least one of the core portion and the clad layer includes a cured product of the resin composition for an optical waveguide. Effect of the Invention

[0012] According to the present disclosure, it is possible to suppress cloudiness and yellowing and to increase transparency. [Brief description of the drawings]

[0013] [Figure 1] FIG. 1 is a cross-sectional view showing the configuration of a dry film for an optical waveguide according to this embodiment. [Diagram 2] 2A to 2C are diagrams illustrating a method for manufacturing an optoelectronic composite wiring board having an optical waveguide according to this embodiment. [Diagram 3] 3A to 3C are diagrams illustrating a method for manufacturing an optoelectronic composite wiring board having an optical waveguide according to this embodiment. [Figure 4] 4A to 4C are diagrams illustrating a method for manufacturing an optoelectronic composite wiring board having an optical waveguide according to this embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] 1.Resin composition for optical waveguide The resin composition for optical waveguide according to the present embodiment contains a (meth)acrylate resin (A), an epoxy resin (B), and a photopolymerization initiator (C). In the following description, "(meth)acrylate" refers to both "acrylate" and "methacrylate".

[0015] The (meth)acrylate resin (A) contains an alicyclic (meth)acrylate compound (A-1), an aromatic (meth)acrylate compound (A-2) and / or a (meth)acrylate monomer (A-3). There are three possible cases for this:

[0016] (1) In the case where the (meth)acrylate resin (A) contains two compounds, namely, an alicyclic (meth)acrylate compound (A-1) and an aromatic (meth)acrylate compound (A-2), and does not contain a (meth)acrylate monomer (A-3), (2) In the case where the (meth)acrylate resin (A) contains two kinds of compounds, namely, an alicyclic (meth)acrylate compound (A-1) and a (meth)acrylate monomer (A-3), and does not contain an aromatic (meth)acrylate compound (A-2), (3) The (meth)acrylate resin (A) contains three types of compounds: an alicyclic (meth)acrylate compound (A-1), an aromatic (meth)acrylate compound (A-2), and a (meth)acrylate monomer (A-3).

[0017] In particular, the resin composition for an optical waveguide in the case of (1) is advantageous for forming the core 11 in an optical waveguide. On the other hand, the resin composition for an optical waveguide in the case of (2) is advantageous for forming the clad layer 8 in an optical waveguide. This not only makes it possible to increase the transparency of each of the core 11 and the clad layer 8, but also makes it possible to easily make the refractive indexes of the two different.

[0018] Here, the alicyclic (meth)acrylate compound (A-1) has a non-aromatic carbon ring in a side chain, and the aromatic (meth)acrylate compound (A-2) has at least two hydroxy groups in one molecule.

[0019] The photopolymerization initiator (C) has an absorption coefficient of 500 mL / (g cm) or less for light with a wavelength of 405 nm.

[0020] Such a resin composition for an optical waveguide can sufficiently suppress clouding or yellowing, and therefore a dry film for an optical waveguide having high transparency can be formed. Furthermore, an optical waveguide having high transparency can also be formed.

[0021] The reason why the cloudiness can be suppressed is believed to be that the resin components contained in the resin composition for optical waveguides have high compatibility with each other and are easily mixed uniformly, and the reason why the yellowing can be suppressed is believed to be that the absorption coefficient for light with a wavelength of 405 nm is low.

[0022] In addition, the resin composition for optical waveguide according to the present embodiment has excellent alkaline developability. Here, the alkaline developability means that the composition exhibits excellent solubility in an alkaline developer used in general alkaline development. In other words, the excellent alkaline developability means that unnecessary uncured portions can be easily removed by using an alkaline developer in the formation of an optical waveguide.

[0023] The developer is not particularly limited, but examples thereof include potassium hydroxide, sodium hydroxide, sodium carbonate, potassium carbonate, sodium phosphate, sodium silicate, ammonia, amines, etc. The developing method is not particularly limited as long as it can remove the uncured portion, but examples thereof include a dipping method, a shower method, a spray method, a brush method, etc.

[0024] <(Meth)acrylate resin (A)> The (meth)acrylate resin (A) contains an alicyclic (meth)acrylate compound (A-1), and an aromatic (meth)acrylate compound (A-2) and / or a (meth)acrylate monomer (A-3).

[0025] In particular, the alicyclic (meth)acrylate compound (A-1) and the aromatic (meth)acrylate compound (A-2) have high compatibility with each other, and therefore, the dry film for optical waveguide can be prevented from becoming cloudy, i.e., the transparency is increased.

[0026] <Alicyclic (meth)acrylate compound (A-1)> The alicyclic (meth)acrylate compound (A-1) has at least one (meth)acrylate group in one molecule, and has a side chain containing a non-aromatic carbon ring.

[0027] A non-aromatic carbocyclic ring is a carbocyclic ring that does not contain an aromatic carbocyclic ring. A non-aromatic carbocyclic ring has only carbon atoms as ring constituent atoms. The non-aromatic carbocyclic ring includes a saturated carbocyclic ring consisting of only a single bond and an unsaturated carbocyclic ring having at least one double bond or triple bond, and is preferably a saturated carbocyclic ring. If it is a saturated carbocyclic ring, unnecessary side reactions are less likely to occur when the curing reaction of the resin composition for optical waveguide proceeds.

[0028] The number of carbon atoms contained in the non-aromatic carbon ring is preferably 3 or more, more preferably 5 or more. On the other hand, the number of carbon atoms contained in the non-aromatic carbon ring is preferably 12 or less, more preferably 7 or less. When the number of carbon atoms contained in the carbon ring is 3 or more and 12 or less, the alicyclic (meth)acrylate compound (A-1) has high storage stability, suitable reactivity, and is easily cured.

[0029] The non-aromatic carbon ring is preferably at least one selected from the group consisting of a cyclopentane ring, a cyclohexane ring, a cycloheptane ring, and a tetrahydrodicyclopentadiene ring, and more preferably a cyclohexane ring. In this case, the curing reaction of the resin composition for optical waveguide is not inhibited, and the curing reaction is easily promoted. In addition, unnecessary side reactions are less likely to occur.

[0030] The hydrogen atoms contained in the non-aromatic carbon ring may be substituted with a substituent that does not impair the effects of the present embodiment. The substituent is not particularly limited, but examples thereof include an alkyl group and a hydroxyl group.

[0031] The alicyclic (meth)acrylate compound (A-1) preferably contains a cyclohexane ring-containing compound (A-11) that contains a structural unit represented by the following formula (1).

[0032] [ka]

[0033] In formula (1), R 1R represents a hydrogen atom or a methyl group. 2 and R 3 are independent of each other, and R 2 represents a saturated hydrocarbon group, R 3 represents a (meth)acrylate group, and n is an integer of 1 or more and 4 or less.

[0034] The saturated hydrocarbon group is not particularly limited, but examples thereof include linear or branched alkylene groups having 1 to 6 carbon atoms, cycloalkylene groups having 3 to 8 carbon atoms, and divalent organic groups formed from a combination thereof.

[0035] The alkylene group is not particularly limited, but examples thereof include a methylene group, an ethylene group, a propylene group, a tetramethylene group, an ethylethylene group, a pentamethylene group, and a hexamethylene group.

[0036] The cycloalkylene group is not particularly limited, but examples thereof include a cyclopentylene group, a cyclohexylene group, and a cyclooctylene group.

[0037] R 2 is preferably a methylene group, an ethylene group, a propylene group, a tetramethylene group, an ethylethylene group, a pentamethylene group, a hexamethylene group, a phenylene group, a cyclohexylene group, or a -CH-phenylene group -CH-, more preferably a methylene group, an ethylene group, or a propylene group, and even more preferably a methylene group.

[0038] By containing the cyclohexane ring-containing compound (A-11), the transparency of the dry film for optical waveguide is improved. In addition, the dry film has excellent tackiness, and the optical waveguide containing the cured product has low optical loss.

[0039] Moreover, the cyclohexane ring-containing compound (A-11) preferably has a structural unit represented by the above formula (1) and a structural unit represented by the following formula (2).

[0040] [ka]

[0041] R 4 R represents a hydrogen atom or a methyl group. 5 represents a hydrogen atom, an alkyl group having from 1 to 6 carbon atoms, or a hydroxyalkyl group having from 1 to 6 carbon atoms. In this case, alkali developability is further improved.

[0042] The number average molecular weight of the alicyclic (meth)acrylate compound (A-1) is preferably 10,000 or more, more preferably 15,000 or more, and even more preferably 21,000 or more. On the other hand, the number average molecular weight of the alicyclic (meth)acrylate compound (A-1) is preferably 30,000 or less, more preferably 29,500 or less, and even more preferably 29,000 or less.

[0043] When the number average molecular weight of the alicyclic (meth)acrylate compound (A-1) is 10,000 or more and 30,000 or less, the transparency of the dry film for optical waveguide is improved, and the alkali developability is further improved.

[0044] The content of the alicyclic (meth)acrylate compound (A-1) is preferably 35 parts by mass or more, more preferably 40 parts by mass or more, per 100 parts by mass of the (meth)acrylate resin (A) and the epoxy resin (B) in total. On the other hand, the content of the alicyclic (meth)acrylate compound (A-1) is preferably 75 parts by mass or less, more preferably 70 parts by mass or less, per 100 parts by mass of the (meth)acrylate resin (A) and the epoxy resin (B) in total.

[0045] When the content of the alicyclic (meth)acrylate compound (A-1) is 35 parts by mass or more and 75 parts by mass or less, the transparency of the dry film for optical waveguide is improved, and the dry film also exhibits excellent alkaline developability.

[0046] Specific examples of the alicyclic (meth)acrylate compound (A-1) include (ACA)Z200M, (ACA)Z230AA, (ACA)Z250, (ACA)Z251, and (ACA)Z300 manufactured by Daicel-Allnex Corporation.

[0047] The alicyclic (meth)acrylate compound (A-1) may be used alone or in combination of two or more kinds.

[0048] <Aromatic (meth)acrylate compound (A-2)> The aromatic (meth)acrylate compound (A-2) is an aromatic compound containing at least two hydroxyl groups in one molecule. The number of hydroxyl groups here does not include the hydroxyl groups of the carboxyl groups. The aromatic (meth)acrylate compound (A-2) has at least one (meth)acrylate group in one molecule, and preferably has at least two (meth)acrylate groups in one molecule. The aromatic (meth)acrylate compound (A-2) has at least one aromatic ring in one molecule.

[0049] The aromatic ring of the aromatic (meth)acrylate compound (A-2) is preferably a hydrocarbon ring, more preferably a monocyclic ring, and further preferably a benzene ring. The aromatic (meth)acrylate compound (A-2) preferably contains an aromatic ring in the main chain.

[0050] The aromatic (meth)acrylate compound (A-2) preferably contains a bisphenol (meth)acrylate compound (A-21) having a bisphenol skeleton.

[0051] The bisphenol (meth)acrylate compound (A-21) has a structure in which the hydrogen atom of the hydroxyl group contained in a general bisphenol compound is substituted with an organic group having a hydroxyl group and a (meth)acrylate group. That is, the bisphenol (meth)acrylate compound (A-21) is a derivative of a bisphenol compound. In particular, it is preferably a derivative of a bisphenol A type compound. By including the bisphenol (meth)acrylate compound (A-21), the optical loss of the cured product is reduced.

[0052] The organic group is a substituent having a hydroxy group and a (meth)acrylate group, and is preferably linear.

[0053] The organic group preferably contains a hydroxyalkylene group. The hydroxyalkylene group is an alkylene group in which at least one hydrogen atom is substituted with a hydroxy group. Specifically, examples of the hydroxyalkylene group include a hydroxymethylene group, a 1-hydroxyethylene group, a 2-hydroxyethylene group, a 1,2-dihydroxyethylene group, a 1-hydroxytrimethylene group, a 2-hydroxytrimethylene group, a 3-hydroxytrimethylene group, a 1-hydroxytetramethylene group, a 2-hydroxytetramethylene group, a 3-hydroxytetramethylene group, a 4-hydroxytetramethylene group, a 1,2-dihydroxytetramethylene group, a 1,3-dihydroxytetramethylene group, a 1,4-dihydroxytetramethylene group, a 2,3-dihydroxytetramethylene group, a 2,4-dihydroxytetramethylene group, and a 4,4-dihydroxytetramethylene group.

[0054] The organic group preferably contains at least one of an oxy group, an alkyleneoxy group, and an alkylenedioxy group. The oxy group is an oxygen atom that is bonded to two different carbon atoms to form an ether bond. The alkyleneoxy group is a substituent in which one of the terminals of the alkylene group is an oxy group. The alkylenedioxy group is a substituent in which both terminals of the alkylene group are oxy groups.

[0055] The organic group preferably contains at least one group selected from the group consisting of a (meth)acrylate group, a hydroxyalkylene group, an oxy group, an alkyleneoxy group, and an alkylenedioxy group, and more preferably contains at least one group selected from the group consisting of a (meth)acrylate group, a hydroxyalkylene group, and an oxy group.

[0056] The number of carbon atoms in the organic group is preferably 1 or more, and more preferably 2 or more. On the other hand, the number of carbon atoms in the organic group is preferably 10 or less, and more preferably 5 or less. When the number of carbon atoms in the organic group is 1 or more and 10 or less, the transparency of the dry film for optical waveguide is increased.

[0057] The content of the aromatic (meth)acrylate compound (A-2) is preferably 25 parts by mass or more, more preferably 30 parts by mass or more, based on 100 parts by mass of the total of the (meth)acrylate resin (A) and the epoxy resin (B). On the other hand, the content of the aromatic (meth)acrylate compound (A-2) is preferably 55 parts by mass or less, more preferably 53 parts by mass or less, based on 100 parts by mass of the total of the (meth)acrylate resin (A) and the epoxy resin (B). If the content of the aromatic (meth)acrylate compound (A-2) is 25 parts by mass or more and 55 parts by mass or less, the transparency of the dry film for optical waveguide is increased.

[0058] The aromatic (meth)acrylate compound (A-2) may be used alone or in combination of two or more kinds.

[0059] <(Meth)acrylate Monomer (A-3)> The (meth)acrylate monomer (A-3) is a compound having at least one (meth)acrylate group in one molecule. The (meth)acrylate monomer (A-3) is also a non-cyclic compound having no cyclic structure in one molecule. In this case, the dry film for optical waveguide is less likely to become cloudy and has high transparency.

[0060] The (meth)acrylate monomer (A-3) preferably has two or more (meth)acrylate groups in one molecule, and more preferably has three or more (meth)acrylate groups in one molecule, which can improve the alkali developability and increase the crosslink density of the cured product.

[0061] The number average molecular weight of the (meth)acrylate monomer (A-3) is preferably 1000 or less, and more preferably 500 or less. On the other hand, the number average molecular weight of the (meth)acrylate monomer (A-3) is preferably 100 or more. When the number average molecular weight of the (meth)acrylate monomer (A-3) is 100 or more and 1000 or less, the dry film for optical waveguide is less likely to become cloudy and has increased transparency.

[0062] The (meth)acrylate monomer (A-3) is not particularly limited, but examples thereof include dipentaerythritol tri(meth)acrylate, dipentaerythritol tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, trimethylolpropane tri(meth)acrylate, and pentaerythritol tri(meth)acrylate.

[0063] As the (meth)acrylate monomer (A-3), commercially available products may be used, and examples thereof include KAYARAD D-310, KAYARAD D-320, KAYARAD D-330, KAYARAD DPHA, KAYARAD GPO-303, KAYARAD TMPTA, KAYARAD THE-330, KAYARAD TPA-330, and KAYARAD PET-30, all of which are manufactured by Nippon Kayaku Co., Ltd.

[0064] <Epoxy resin (B)> The epoxy resin (B) contains an epoxy compound having photocurability and high transparency. The epoxy group of the epoxy resin (B) reacts with the carboxy group of the (meth)acrylate resin (A) to increase the degree of curing. As a result, the heat resistance of the cured product of the resin composition for optical waveguide is increased.

[0065] The epoxy resin (B) preferably contains a liquid epoxy compound (B-1). The liquid epoxy compound (B-1) is liquid at 25°C. The viscosity of the liquid epoxy compound (B-1) at 25°C is preferably 30000 mPa·s or less, more preferably 17000 mPa·s or less. On the other hand, the viscosity of the liquid epoxy compound (B-1) at 25°C is preferably 100 mPa·s or more. If the viscosity is 100 mPa·s or more and 30000 mPa·s or less, the compatibility with the (meth)acrylate resin (A) is increased, and a uniform dry film for optical waveguides can be formed.

[0066] The liquid epoxy compound (B-1) preferably contains a liquid bisphenol A type epoxy compound (B-11). The liquid bisphenol A type epoxy compound (B-11) is a bisphenol A type epoxy compound that is liquid at 25°C and has one or two epoxy groups per molecule. The use of the liquid bisphenol A type epoxy compound (B-11) enhances alkaline developability. Specific examples of the liquid bisphenol A type epoxy compound (B-11) include 840, 840-S, 850, 850-S, EXA-850CR, etc., manufactured by DIC Corporation.

[0067] The liquid bisphenol A type epoxy compound (B-11) may be one of the compounds exemplified above, or two or more of them may be used in combination.

[0068] The content of the epoxy resin (B) is preferably 1 part by mass or more, more preferably 3 parts by mass or more, per 100 parts by mass of the total of the (meth)acrylate resin (A) and the epoxy resin (B). On the other hand, the content of the epoxy resin (B) is preferably 10 parts by mass or less, more preferably 7 parts by mass or less, per 100 parts by mass of the total of the (meth)acrylate resin (A) and the epoxy resin (B). By having the content of the epoxy resin (B) be 1 part by mass or more and 10 parts by mass or less, the light loss is reduced.

[0069] <Photopolymerization initiator (C)> The photopolymerization initiator (C) is not particularly limited as long as it has an absorption coefficient of 500 mL / (g·cm) or less for light with a wavelength of 405 nm and can promote the light-induced curing reaction of the resin composition for optical waveguides. The absorption coefficient for light with a wavelength of 405 nm is a value obtained by measuring a solution of the photopolymerization initiator (C) with a concentration of 0.1 g / 1 L in a solvent (acetonitrile or methanol) at a wavelength of 405 nm and an optical path length of 1 cm. By using such a photopolymerization initiator (C), yellowing of the dry film for optical waveguides is suppressed and transparency is increased.

[0070] The photoinitiator (C) preferably has an absorption coefficient of 100 mL / (g cm) or less, more preferably 10 mL / (g cm) or less, for light with a wavelength of 405 nm. In this case, the dry film for optical waveguides has even higher transparency.

[0071] The photopolymerization initiator (C) is not particularly limited as long as the effects of this embodiment can be obtained, but it is preferable for the photopolymerization initiator (C-1) to contain a radical polymerization initiator.

[0072] The radical polymerization initiator (C-1) is not particularly limited, but examples thereof include 1-hydroxy-cyclohexyl-phenyl-ketone, 2-hydroxy-2-methyl-1-phenyl-propan-1-one, 1-[4-(2-hydroxyethoxy)-phenyl]-2-hydroxy-2-methyl-1-propan-1-one, oxy-phenyl-acetic acid 2-[2-oxo-2-phenyl-acetoxy-ethoxy]-ethyl ester, oxy-phenyl-acetic acid 2-[2-hydroxy-ethoxy]-ethyl ester, 2-hydroxy-1-{4-[4-(2-hydroxy-2-methyl-propionyl)-benzyl]-phenyl}-2-methyl-propan-1-one, and the like.

[0073] As the radical polymerization initiator (C-1), commercially available ones may be used, and examples thereof include Irgacure 127, Irgacure 184, Irgacure 500, Irgacure 651, Irgacure 754, Irgacure 907, Irgacure 1173, and Irgacure 2959.

[0074] The content of the photopolymerization initiator (C) is preferably 0.1% by mass or more, more preferably 5% by mass or more, based on the total solid content of the resin composition for optical waveguides. On the other hand, the content of the photopolymerization initiator (C) is preferably 20% by mass or less, more preferably 15% by mass or less, based on the total solid content of the resin composition for optical waveguides.

[0075] When the content of the photopolymerization initiator (C) is 0.1% by mass or more and 20% by mass or less, the curing of the resin composition for optical waveguide is accelerated, the chemical resistance of the cured product is improved, and the optical loss of the formed optical waveguide can be reduced.

[0076] The photopolymerization initiator (C) may be used alone or in combination of two or more. In addition, a photopolymerization initiator (C) that exhibits high photosensitivity to the wavelength to be irradiated may be used appropriately. Furthermore, other photopolymerization initiators (C-2) may be used within a range that does not impair the effects of this embodiment.

[0077] <Additives> The optical waveguide resin composition may contain additives within the range that does not impair the effects of the present embodiment. The additives are not particularly limited, but examples thereof include antioxidants, leveling agents, solvents, etc. The antioxidants are not particularly limited, but examples thereof include phenol-based antioxidants, phosphite-based antioxidants, sulfur-based antioxidants, etc.

[0078] Examples of the phenol-based antioxidant include AO-20, AO-30, AO-40, AO-50, AO-60, and AO-80 manufactured by Adeka Corporation; and SUMILIZERGA-80 manufactured by Sumitomo Chemical Co., Ltd.

[0079] Examples of the phosphite-based antioxidants include PEP-8, PEP-36, HP-10, 2112, 1178, and 1500 manufactured by Adeka Corporation, and JP-360 and JP-3CP manufactured by Johoku Chemical Industry Co., Ltd.

[0080] Examples of the sulfur-based antioxidant include AO-412S and AO-503 manufactured by ADEKA CORPORATION, and SUMILIZER TP-D manufactured by Sumitomo Chemical Co., Ltd.

[0081] The antioxidant may be used alone or in combination of two or more. In particular, it is preferable to use a phenol-based antioxidant. By including an antioxidant in the resin composition for optical waveguide, an optical waveguide having high heat resistance can be suitably formed.

[0082] When the resin composition for optical waveguide contains an antioxidant, the content of the antioxidant is preferably more than 0 part by mass, more preferably 0.2 parts by mass or more, and even more preferably 0.3 parts by mass or more, relative to 100 parts by mass of the resin composition for optical waveguide. On the other hand, the content of the antioxidant is preferably 5 parts by mass or less, more preferably 2 parts by mass or less, and even more preferably 1 part by mass or less, relative to 100 parts by mass of the resin composition for optical waveguide.

[0083] When the resin composition for optical waveguide contains an antioxidant, if the content of the antioxidant exceeds 5 parts by mass, the antioxidant may act as a plasticizer and reduce the heat resistance of the cured product. Therefore, when the resin composition for optical waveguide contains an antioxidant, the content of the antioxidant is preferably more than 0 parts by mass and not more than 5 parts by mass, which allows the suitable formation of an optical waveguide with high heat resistance.

[0084] As the leveling agent, various dispersants that are generally used as dispersants can be used, such as PF-636 manufactured by OMNOVASolutions.

[0085] As described above, the resin composition for an optical waveguide according to this embodiment can form an optical waveguide having high heat resistance.

[0086] <Curing method> The method for curing the resin composition for optical waveguide is not particularly limited as long as photocuring proceeds, but specifically, the resin composition for optical waveguide is irradiated with light having a wavelength of 365 nm and heat-treated at 140° C. for 10 minutes. More specifically, the resin composition for optical waveguide is irradiated with light having a wavelength of 365 nm at 1000 mJ / cm 2 and then heat-treating for 10 minutes at 140° C. The absorption wavelength and heat-treating conditions are not particularly limited as long as photocuring proceeds.

[0087] The photocuring of the resin composition for optical waveguide according to the present embodiment can be carried out in the same manner as described above by projection exposure using a photomask, and therefore a suitable optical waveguide can be formed. Photocuring can also be carried out by using light outside the i-line region.

[0088] 2. Dry film for optical waveguides The resin composition for an optical waveguide according to this embodiment can be used as a material for a dry film for an optical waveguide used when forming an optical waveguide.

[0089] The dry film for optical waveguide according to the present embodiment is not particularly limited as long as it comprises a resin layer 1 containing the resin composition for optical waveguide. Specifically, as shown in FIG. 1, the dry film for optical waveguide may comprise a film substrate 2 on one side of the resin layer 1 and a protective film 3 on the other side. The dry film for optical waveguide may comprise not only the film substrate 2 and the protective film 3 but also other layers as long as it comprises the resin layer 1. The film substrate 2 and the protective film 3 are not essential. FIG. 1 is a cross-sectional view showing the configuration of the dry film for optical waveguide according to the present embodiment.

[0090] The resin layer 1 contains the above-mentioned resin composition for optical waveguide or semi-cured product. Since the resin layer 1 is formed from the resin composition for optical waveguide according to the present embodiment, the tackiness is suppressed. Therefore, the processability is improved.

[0091] The thickness of the dry film for optical waveguide is preferably adjusted appropriately, and is preferably 20 μm or more, more preferably 30 μm or more. If the thickness is 20 μm or more, the cured product has sufficient physical strength. On the other hand, the thickness of the dry film for optical waveguide is preferably 100 μm or less, more preferably 80 μm or less. If the thickness is 100 μm or less, a suitable optical waveguide can be formed.

[0092] The film substrate 2 is not particularly limited, but examples thereof include polyesters such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate; polyolefins such as polyethylene and polypropylene; polycarbonate, polyamide, polyimide, polyamideimide, polyetherimide, polyethersulfide, polyethersulfone, polyetherketone, polyphenylene ether, polyphenylene sulfide, polyarylate, polysulfone, and liquid crystal polymers. In particular, the film substrate 2 is preferably polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polypropylene, polycarbonate, polyamide, polyimide, polyamideimide, polyphenylene ether, polyphenylene sulfide, polyarylate, or polysulfone. These have excellent flexibility and toughness.

[0093] The thickness of the film substrate 2 is preferably adjusted appropriately, but is preferably, for example, 3 μm or more and 250 μm or less. With such a thickness, a dry film for optical waveguide having excellent film strength and flexibility can be manufactured. As a result, the processability of the dry film for optical waveguide is improved, and a suitable optical waveguide can be easily formed.

[0094] The surface of the film substrate 2 that comes into contact with the resin layer 1 may be subjected to a release treatment using a fluorine-containing compound or the like. By performing the release treatment, the resin layer 1 can be easily peeled off from the film substrate 2.

[0095] The protective film 3 is not particularly limited, but examples thereof include polyesters such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate; polyolefins such as polyethylene and polypropylene. In particular, the protective film 3 is preferably a polyester such as polyethylene terephthalate; or a polyolefin such as polyethylene and polypropylene. These have excellent flexibility and toughness.

[0096] The thickness of the protective film 3 is preferably adjusted appropriately, but is preferably, for example, 10 μm or more and 250 μm or less. With such a thickness, a dry film for optical waveguide having excellent film strength and flexibility can be manufactured. As a result, the processability of the dry film for optical waveguide is improved, and a suitable optical waveguide can be easily formed. In addition, a peeling treatment may be performed in the same manner as the film substrate 2.

[0097] The method for forming the dry film for optical waveguide is not particularly limited, but may be, for example, the following method. First, a solvent or the like is added to the resin composition for optical waveguide to form a varnish, and the varnish is applied onto the film substrate 2. This application may be performed using a comma coater or the like. By drying this varnish, a resin layer 1 is formed on the film substrate 2. Furthermore, a protective film 3 is laminated onto the resin layer 1. As a lamination method, for example, a thermal lamination method may be used. The resin layer 1 in the dry film for optical waveguide is used as a material for the optical waveguide. The dry film for optical waveguide may be used when forming the core of the optical waveguide, or may be used when forming the clad.

[0098] 3.Optical waveguide A method for forming an optical waveguide according to this embodiment will be described with reference to Figures 2A to 2C, 3A to 3C, and 4A to 4C. Here, a method for manufacturing an optoelectronic composite wiring board including an optical waveguide will be described. Figures 2A to 2C, 3A to 3C, and 4A to 4C are diagrams for explaining the method for manufacturing an optoelectronic composite wiring board including an optical waveguide according to this embodiment.

[0099] First, as shown in Fig. 2A, a substrate 5 having an electric circuit 9 is prepared. Next, as shown in Fig. 2B, a cladding layer 8 (lower cladding layer 10) is formed on the surface of the substrate 5 on which the electric circuit 9 is provided. The method for forming the lower cladding layer 10 is not particularly limited, but examples thereof include a method in which a dry film for optical waveguides (resin layer 1) is superimposed on the substrate 5, and light is irradiated to a predetermined portion of the dry film for optical waveguides to cure the portion irradiated with light.

[0100] Next, a core portion 11 is formed on the lower clad layer 10 using a dry film for optical waveguide. Specifically, as shown in FIG. 2C, the protective film 3 is peeled off from the dry film for optical waveguide. Then, as shown in FIG. 3A, the resin layer 1 is laminated so as to be disposed on the lower clad layer 10, and then the film substrate 2 is peeled off. Next, as shown in FIG. 3B, a light source 12 is used to irradiate a predetermined portion of the resin layer 1 with light having a wavelength of 365 nm (indicated by a dotted arrow), and the portion of the resin layer 1 irradiated with light is photocured. Thereafter, development is performed to form a core portion 11 as shown in FIG. 3C. The core portion 11 is the portion of the resin layer 1 irradiated with light.

[0101] The method of development is not particularly limited, but an example is a method of removing the uncured portion of the resin layer 1 with an alkaline developer. The uncured portion of the resin layer 1 is the portion that has not been irradiated with light.

[0102] Next, a cladding layer 8 (upper cladding layer 13) is formed using a dry film for optical waveguides. The method for forming the upper cladding layer 13 is not particularly limited, but for example, as shown in Fig. 4A, a resin layer 1 is laminated using a dry film for optical waveguides so as to cover the lower cladding layer 10 and the core portion 11. The dry film for optical waveguides may include a film substrate 2 and a protective film 3.

[0103] Next, as shown in Fig. 4B, a light source 12 is used to irradiate a predetermined portion of the resin layer 1 with light rays having a wavelength of 365 nm (indicated by a dotted arrow), and the portion of the resin layer 1 irradiated with light is photocured. By doing so, the portion of the resin layer 1 irradiated with light becomes the upper cladding layer 13. Note that, as shown in Fig. 4C, a light beam having a wavelength of 365 nm is irradiated to a portion other than where the via 15 is to be formed, and then development is performed, thereby forming the via 15 as shown in Fig. 4C.

[0104] As described above, an optical waveguide can be formed using the dry film for optical waveguide according to this embodiment. That is, the optical waveguide shown in Fig. 4C includes a core portion 11 and a clad layer 8 (a lower clad layer 10 and an upper clad layer 13). The upper clad layer 13 covers the core portion 11. The upper clad layer 13 is a cured product of a resin composition for optical waveguide.

[0105] As described above, the dry film for optical waveguide according to this embodiment includes the resin layer 1. The optical waveguide according to this embodiment also includes the core portion 11 and the clad layer 8 covering the core portion 11, and at least one of the core portion 11 and the clad layer 8 includes a cured product of the resin composition for optical waveguide.

[0106] In particular, the core 11 is preferably formed from the resin composition for optical waveguide in the above-mentioned case (1). In this case, the (meth)acrylate resin (A) contains two kinds of compounds, an alicyclic (meth)acrylate compound (A-1) and an aromatic (meth)acrylate compound (A-2), and does not contain a (meth)acrylate monomer (A-3).

[0107] On the other hand, the cladding layer 8 (lower cladding layer 10 and upper cladding layer 13) is preferably formed from the resin composition for optical waveguide in the above case (2). In this case, the (meth)acrylate resin (A) contains two kinds of compounds, an alicyclic (meth)acrylate compound (A-1) and a (meth)acrylate monomer (A-3), but does not contain an aromatic (meth)acrylate compound (A-2).

[0108] This not only makes it possible to increase the transparency of each of the core portion 11 and the cladding layer 8, but also makes it possible to easily make the refractive indexes of the two different.

[0109] 4. Aspects As is apparent from the above embodiment, the present disclosure includes the following aspects. In the following, reference symbols are given in parentheses only to clarify the correspondence with the embodiment.

[0110] The first aspect is a resin composition for optical waveguides, which contains a (meth)acrylate resin (A), an epoxy resin (B), and a photopolymerization initiator (C). The (meth)acrylate resin (A) contains an alicyclic (meth)acrylate compound (A-1), an aromatic (meth)acrylate compound (A-2) and / or a (meth)acrylate monomer (A-3). The alicyclic (meth)acrylate compound (A-1) has a non-aromatic carbon ring in a side chain. The aromatic (meth)acrylate compound (A-2) has at least two hydroxyl groups in one molecule. The photopolymerization initiator (C) has an absorption coefficient of 500 mL / (g cm) or less for light having a wavelength of 405 nm.

[0111] According to this embodiment, it is possible to suppress clouding and yellowing and to increase transparency.

[0112] The second aspect is the resin composition for optical waveguide according to the first aspect, wherein the alicyclic (meth)acrylate compound (A-1) contains a cyclohexane ring-containing compound (A-11) having a structural unit of the following formula (1):

[0113] [ka] (In formula (1), R 1 R represents a hydrogen atom or a methyl group. 2 and R 3 are independent of each other, and R 2 represents a saturated hydrocarbon group, and R 3 represents an acrylate group or a methacrylate group; and n is an integer of 1 or more and 4 or less.

[0114] According to this embodiment, the transparency can be further improved.

[0115] A third aspect is the resin composition for an optical waveguide according to the first or second aspect. In the third aspect, the aromatic (meth)acrylate compound (A-2) contains a bisphenol (meth)acrylate compound (A-21).

[0116] According to this embodiment, the transparency can be further improved.

[0117] A fourth aspect is a resin composition for optical waveguides based on any one of the first to third aspects. In the fourth aspect, the content of the alicyclic (meth)acrylate compound (A-1) is 35 parts by mass or more and 75 parts by mass or less, based on 100 parts by mass in total of the (meth)acrylate resin (A) and the epoxy resin (B).

[0118] According to this embodiment, the transparency can be further improved.

[0119] A fifth aspect is a resin composition for optical waveguides based on any one of the first to fourth aspects. In the fifth aspect, the content of the aromatic (meth)acrylate compound (A-2) is 25 parts by mass or more and 55 parts by mass or less, based on 100 parts by mass in total of the (meth)acrylate resin (A) and the epoxy resin (B).

[0120] According to this embodiment, the transparency can be further improved.

[0121] A sixth aspect is the resin composition for an optical waveguide according to any one of the first to fifth aspects. In the sixth aspect, the epoxy resin (B) contains a liquid epoxy compound (B-1).

[0122] According to this embodiment, the transparency can be further improved.

[0123] A seventh aspect is the resin composition for an optical waveguide according to any one of the first to sixth aspects. In the seventh aspect, the photopolymerization initiator (C) contains a radical polymerization initiator (C-1).

[0124] According to this embodiment, the transparency can be further improved.

[0125] An eighth aspect is a dry film for an optical waveguide, comprising a resin layer (1) containing a resin composition for an optical waveguide based on any one of the first to seventh aspects or a semi-cured product of the resin composition for an optical waveguide.

[0126] According to this embodiment, it is possible to suppress clouding and yellowing and to increase transparency.

[0127] A ninth aspect is a dry film for an optical waveguide based on the eighth aspect. The ninth aspect further includes at least one of a film substrate (2) and a protective film (3).

[0128] According to this embodiment, the handleability of the dry film for optical waveguide is improved.

[0129] A tenth aspect is an optical waveguide comprising a core portion (11) and a clad layer (8) covering the core portion (11). At least one of the core portion (11) and the clad layer (8) contains a cured product of a resin composition for optical waveguide according to any one of the first to seventh aspects.

[0130] According to this embodiment, it is possible to suppress clouding and yellowing and to increase transparency.

[0131] An eleventh aspect is the optical waveguide according to the tenth aspect. In the eleventh aspect, the core portion (11) comprises a cured product of the optical waveguide resin composition containing the alicyclic (meth)acrylate compound (A-1) and the aromatic (meth)acrylate compound (A-2). The cladding layer (8) comprises a cured product of the optical waveguide resin composition containing the alicyclic (meth)acrylate compound (A-1) and the (meth)acrylate monomer (A-3).

[0132] According to this embodiment, the transparency of both the core portion (11) and the cladding layer (8) can be further improved. EXAMPLES

[0133] The present disclosure will be specifically described below with reference to examples, but the present disclosure is not limited to the following examples.

[0134] [(Meth)acrylate resin (A)] Alicyclic (meth)acrylate compound (A-1), cyclohexane ring-containing compound (A-11) having a structural unit of formula (1), manufactured by Daicel-Allnex Corporation, trade name: (ACA)Z250 Aromatic (meth)acrylate compound (A-2), bisphenol (meth)acrylate compound (A-21), manufactured by Daicel Corporation, product name: EBECRYL600 (Meth)acrylate monomer (A-3), manufactured by Nippon Kayaku Co., Ltd., product name: KAYARAD PET-30 Other (meth)acrylate compounds (A-4), manufactured by Shin-Nakamura Chemical Co., Ltd., product name: ABE-300.

[0135] [Epoxy resin (B)] Liquid epoxy compound (B-1), liquid bisphenol A type epoxy compound (B-11), manufactured by DIC Corporation, product name: 850-S, epoxy equivalent: 183-193g / eq.

[0136] [Photopolymerization initiator (C)] Radical polymerization initiator (C-1), manufactured by IGM Resins BV, product name: Irgacure 754, with an absorption coefficient of 500 mL / (g cm) or less for light with a wavelength of 405 nm. Other photoinitiators (C-2), manufactured by IGM Resins BV, trade name: Omnirad819, have an absorption coefficient of more than 500 mL / (g·cm) for light with a wavelength of 405 nm.

[0137] [Resin composition for optical waveguide] The resin composition for optical waveguide was prepared as follows. First, each material was weighed into a glass container so as to obtain the composition (parts by mass) shown in Table 1, and 2-butanone, toluene, and propylene glycol monomethyl ether acetate were added as solvents in a ratio of 7:2:1. The mixture was stirred under reflux at 80°C to obtain a uniform varnish-like composition in which all soluble solids were dissolved. The obtained varnish-like composition was filtered through a membrane filter made of polytetrafluoroethylene (PTFE) with a pore size of 1 μm. This removed solid foreign matter contained therein. The filtered varnish-like resin composition for optical waveguide was used below.

[0138] [Dry film for optical waveguides] Next, the above-mentioned varnish-like resin composition for optical waveguide was used to prepare a dry film for optical waveguide. Specifically, the varnish-like resin composition for optical waveguide was applied to a PET film (manufactured by Toyobo Co., Ltd., product name: A4100) as a film substrate using a multi-coater with a comma coater head manufactured by Hirano Tecseed Co., Ltd., so that a layer made of the resin composition for optical waveguide was 50 μm thick, and then dried at 80° C. for 30 minutes. As a result, a resin layer (a layer made of the resin composition for optical waveguide) having a thickness of 50 μm was formed on the PET film.

[0139] [Transparency] The appearance of the dry film for optical waveguide obtained as described above was visually observed and evaluated as "transparent," "opaque," or "yellow." If the dry film for optical waveguide is transparent, the cured product thereof may also be considered to be transparent.

[0140] [Table 1] [Explanation of symbols]

[0141] 1 Resin layer 2. Film substrate 3 Protective film 8 Cladding Layer 11 Core

Claims

1. Contains a (meth)acrylate resin (A), an epoxy resin (B), and a photopolymerization initiator (C), The (meth)acrylate resin (A) contains an alicyclic (meth)acrylate compound (A-1), and an aromatic (meth)acrylate compound (A-2) and / or a (meth)acrylate monomer (A-3), The alicyclic (meth)acrylate compound (A-1) has a non-aromatic carbon ring in a side chain, The aromatic (meth)acrylate compound (A-2) has at least two hydroxy groups in one molecule, The photopolymerization initiator (C) has an absorption coefficient of 500 mL / (g cm) or less for light having a wavelength of 405 nm. Resin composition for optical waveguides.

2. The alicyclic (meth)acrylate compound (A-1) contains a cyclohexane ring-containing compound (A-11) having a structural unit represented by the following formula (1): The resin composition for an optical waveguide according to claim 1 . 【Chemistry 1】 (In formula (1), R １ represents a hydrogen atom or a methyl group. ２ and R ３ are independent of each other, and R ２ represents a saturated hydrocarbon group, R ３ represents an acrylate group or a methacrylate group; and n is an integer of 1 to 4.

3. The aromatic (meth)acrylate compound (A-2) contains a bisphenol (meth)acrylate compound (A-21). The resin composition for an optical waveguide according to claim 1 .

4. the content of the alicyclic (meth)acrylate compound (A-1) is 35 parts by mass or more and 75 parts by mass or less, based on 100 parts by mass in total of the (meth)acrylate resin (A) and the epoxy resin (B); The resin composition for an optical waveguide according to claim 1 .

5. the content of the aromatic (meth)acrylate compound (A-2) is 25 parts by mass or more and 55 parts by mass or less, based on 100 parts by mass in total of the (meth)acrylate resin (A) and the epoxy resin (B); The resin composition for an optical waveguide according to claim 1 .

6. The epoxy resin (B) contains a liquid epoxy compound (B-1). The resin composition for an optical waveguide according to claim 1 .

7. The photopolymerization initiator (C) contains a radical polymerization initiator (C-1). The resin composition for an optical waveguide according to claim 1 .

8. A resin layer comprising the resin composition for optical waveguide according to any one of claims 1 to 7 or a semi-cured product of the resin composition for optical waveguide. Dry film for optical waveguides.

9. Further comprising at least one of a film substrate and a protective film; The dry film for optical waveguide according to claim 8 .

10. A core portion and a clad layer covering the core portion, At least one of the core portion and the clad layer comprises a cured product of the resin composition for optical waveguide according to any one of claims 1 to 7. optical waveguide.

11. the core portion comprises a cured product of the resin composition for optical waveguide comprising the alicyclic (meth)acrylate compound (A-1) and the aromatic (meth)acrylate compound (A-2); the clad layer comprises a cured product of the resin composition for optical waveguide, the resin composition comprising the alicyclic (meth)acrylate compound (A-1) and the (meth)acrylate monomer (A-3); 11. The optical waveguide according to claim 10.

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