Optical waveguide resin composition, dry film, resin-equipped film, liquid material, optical waveguide, and method for producing optical waveguide

Abstract

This optical waveguide resin composition comprises: an epoxy compound (A); an anthracene-based photosensitizer (B); a first photocationic polymerization initiator (C); and a second photocationic polymerization initiator (D) and / or a benzotriazole-based ultraviolet absorber (E), wherein the first photocationic polymerization initiator (C) has a conjugate acid strength of not less than the strength of HSbF6 and has a first anion part; and the second photocationic polymerization initiator (D) has a conjugate acid strength lower than the strength of HSbF6 and has a second anion part.

Description

Resin composition for optical waveguides, dry film, resin-coated film, liquid material, optical waveguide, and method for manufacturing an optical waveguide.

[0001] The present invention relates to a resin composition for optical waveguides, a dry film, a resin-coated film, a liquid material, an optical waveguide, and a method for manufacturing an optical waveguide.

[0002] Traditionally, optical fibers have been the dominant transmission medium in FTTH (Fiber to the Home) and long-distance and medium-distance communications in the automotive sector. In recent years, however, there has been a growing need for high-speed transmission using light even over short distances of less than 1 meter. For this area, optical waveguide type optical wiring boards are suitable because they offer high-density wiring (narrow pitch, branching, crossing, multilayering, etc.), surface mountability, integration with electrical substrates, and small-diameter bending, which are not possible with optical fibers.

[0003] Optical waveguides are obtained by forming a cladding portion and a core portion using two types of highly transparent, UV-curable optical waveguide resin compositions with different refractive indices. The cladding portion and core portion of the optical waveguide can be formed by exposure and development. Exposure is performed, for example, by irradiating a portion of a layer, film, etc., containing an optical waveguide resin composition including an epoxy compound, a photocationic polymerization initiator, etc., with ultraviolet light through a mask, or by directly drawing with laser light. Development is performed, for example, by removing the uncured portion after exposure and leaving the cured portion using a developer solution containing an organic solvent and water (see, for example, Patent Document 1).

[0004] Direct imaging (DI), a method of exposure that uses laser light to directly draw, is expected to improve patterning accuracy, stabilize quality, and significantly increase yield in the manufacturing of optical waveguides.

[0005] Japanese Patent Publication No. 2007-292964

[0006] The present invention aims to provide a resin composition for optical waveguides that enables high-precision patterning in the wavelength range of direct image exposure.

[0007] The inventors of this invention have diligently conducted research to solve the above problems and have arrived at the present invention.

[0008] The optical waveguide resin composition according to the present invention comprises an epoxy compound (A), an anthracene-based photosensitizer (B), a first photocationic polymerization initiator (C), and one or more of a second photocationic polymerization initiator (D) and a benzotriazole-based ultraviolet absorber (E), wherein the first photocationic polymerization initiator (C) has a conjugate acid strength of HSbF ６ A polymerization initiator having a strength greater than or equal to HSbF, and having a first anion portion, wherein the second photocationic polymerization initiator (D) has a conjugate acid strength of HSbF ６ This polymerization initiator has a strength lower than that of the first one and has a second anionic portion.

[0009] Figure 1 is a schematic cross-sectional diagram illustrating an example of a method for forming an optical waveguide using a dry film according to this embodiment. Specifically, Figure 1(a) is a schematic diagram showing the stage in which a cladding dry film is laminated onto the surface of a substrate. Figure 1(b) is a schematic diagram showing the stage in which an undercladding layer is formed. Figure 1(c) is a schematic diagram showing the stage in which a core dry film is exposed to direct imaging. Figure 1(d) is a schematic diagram showing the stage in which a core is formed on the surface of the undercladding. Figure 1(e) is a schematic diagram showing the stage in which a cladding dry film is laminated to cover the undercladding and the core. Figure 1(f) is a schematic diagram showing the stage in which an optical waveguide is formed.

[0010] The wavelength range of the light source used in DI exposure is in the long-wavelength region of approximately 375 nm or higher. However, the photocationic polymerization initiators contained in currently widely used optical waveguide resin compositions have almost no absorption from light sources on the long-wavelength side of 375 nm or higher, making photocuring by DI exposure difficult.

[0011] To enhance absorption from long-wavelength light sources, one possible method is to increase the content of the photocationic polymerization initiator in the optical waveguide resin composition. However, simply increasing the content of the photocationic polymerization initiator may lead to an increase in optical loss at a wavelength of 1310 nm in the optical waveguide. Alternatively, one could consider incorporating a sensitizer into the optical waveguide resin composition, or replacing the polymerization initiator with a photocationic polymerization initiator suitable for absorption from long-wavelength light sources. However, incorporating these compounds into the optical waveguide resin composition may result in a core width wider than desired, leading to inferior patterning accuracy.

[0012] As a result of diligent research by the present inventors, it was found that a resin composition comprising an epoxy compound (A), an anthracene-based photosensitizer (B), a first photocationic polymerization initiator (C) having a conjugate acid strength of a predetermined strength or higher and a predetermined anion portion, and one or more of a second photocationic polymerization initiator (D) having a conjugate acid strength lower than the predetermined strength and a predetermined anion portion, and a benzotriazole-based ultraviolet absorber (E), can be obtained that enables high-precision patterning in the wavelength range of DI exposure.

[0013] Thus, according to the present invention, it is possible to provide a resin composition for optical waveguides that enables high-precision patterning in the wavelength range of direct image exposure.

[0014] In this specification, "epoxy compound" means a component that includes both an epoxy resin as a polymer and a monomer capable of forming the epoxy resin. Furthermore, "epoxy compound" includes both liquid epoxy compounds and solid epoxy compounds. In this specification, with respect to epoxy compounds, "liquid" means liquid at room temperature, and "solid" means solid at room temperature. Furthermore, in this specification, "bisphenol A type epoxy compound" means an epoxy compound having a bisphenol A type structure in its monomer structure.

[0015] Embodiments of the present invention will be described in detail below with reference to the drawings. However, the scope of the present invention is not limited to the embodiments described herein, and various modifications can be made without impairing the spirit of the invention.

[0016] 1. Resin composition for optical waveguides The resin composition for optical waveguides according to this embodiment (hereinafter also simply referred to as "resin composition") comprises an epoxy compound (A), an anthracene-based photosensitizer (B), a first photocationic polymerization initiator (C), a second photocationic polymerization initiator (D), and one or more benzotriazole-based ultraviolet absorbers (E).

[0017] The following provides a detailed description of each component contained in the resin composition, the ratio of each component's content, and the physical properties of the resin composition.

[0018] [Epoxy Compound (A)] The resin composition according to this embodiment includes epoxy compound (A). The type of epoxy compound (A) is not particularly limited as long as it is any epoxy compound known to those skilled in the art that provides the effect of high-precision patterning in the wavelength range of DI exposure according to this embodiment. Specifically, epoxy compound (A) may be either a liquid epoxy compound or a solid epoxy compound.

[0019] The epoxy compound (A) is not particularly limited and includes, for example, bisphenol A type epoxy resin, hydrogenated bisphenol A type epoxy resin, bisphenol F type epoxy resin, polyfunctional epoxy resin, bisphenol E type epoxy resin, brominated epoxy resin, fluorinated epoxy resin, aromatic epoxy resin, novolac type epoxy resin, biphenyl type epoxy resin, alicyclic epoxy resin, aliphatic epoxy resin, and the like.

[0020] Among the epoxy compounds (A), it is preferable to include a bisphenol A type epoxy compound from the viewpoint of high transparency and easy UV curing. The epoxy equivalent of the bisphenol A type epoxy compound is not particularly limited, but is preferably about 170 g / eq to 1200 g / eq.

[0021] Bisphenol A type epoxy compounds may be synthesized by known methods, but commercially available products may also be used. For example, commercially available solid bisphenol A type epoxy compounds include "1001", "1002", "1003", "1055", "1004", "1004AF", "1003F", "1004F", "1005F", "1004FS", "1006FS", and "1007FS" from Mitsubishi Chemical Group Corporation. Also, commercially available liquid bisphenol A type epoxy compounds include "850S" from DIC Corporation and "JER® 825" from Mitsubishi Chemical Corporation.

[0022] The epoxy compound (A) preferably contains a polyfunctional epoxy compound, as this can improve the glass transition temperature of the cured product and, consequently, impart good heat resistance to the optical waveguide. Furthermore, it is more preferable that the polyfunctional epoxy compound has a bisphenol A type structure. The epoxy equivalent of the polyfunctional epoxy compound is not particularly limited, but is preferably, for example, about 150 g / eq to 250 g / eq.

[0023] Examples of polyfunctional epoxy compounds include 2-[4-(2,3-epoxypropoxy)phenyl]-2-[4-[1,1-bis[4-([2,3-epoxypropoxy]phenyl)]ethyl]phenyl]propane, and cresol novolac type epoxy compounds. Polyfunctional epoxy compounds may be synthesized by known methods, or commercially available products may be used. Examples of commercially available products include "VG3101M80" from Printec Co., Ltd., "EHPE-3150" from Daicel Corporation, and "EPPN-502" from Nippon Kayaku Co., Ltd.

[0024] The epoxy compound (A) may be used alone, or preferably in combination of two or more. Specifically, epoxy compound (A) preferably contains two or more bisphenol A type epoxy compounds with different melting points. Including two or more bisphenol A type epoxy compounds with different melting points facilitates adjustment of the melting point of the dry film. Furthermore, it significantly reduces stickiness during film use. As a result, not only is productivity improved, but appropriate adhesion is also provided, thus improving the laminating properties of the film.

[0025] [Anthracene-based photosensitizer (B)] The resin composition according to this embodiment contains an anthracene-based photosensitizer (B). By containing the anthracene-based photosensitizer (B) in the resin composition, the absorption of light in the long wavelength region of approximately 375 nm or more during DI exposure is increased, and the resin composition can be photocured in the long wavelength region.

[0026] The anthracene-based photosensitizer (B) preferably contains a compound represented by the structure of the following formula (1). In the following formula (1), R １ Each of these is an alkyl group having 1 to 10 carbon atoms.

[0027] When the anthracene-based photosensitizer (B) contains a compound represented by the structure of formula (1) above, DI exposure in the long wavelength region of approximately 375 nm or more can be performed more reliably.

[0028] The compound represented by the structure of formula (1) above is not particularly limited, but examples include anthracene, 2-ethyl-9,10-dimethoxyanthracene, 9,10-dimethylanthracene, 9,10-dibutoxyanthracene (DBA), 9,10-dipropoxyanthracene, 9,10-diethoxyanthracene, 9,10-bis(octanoyloxy)anthracene, 1,4-dimethoxyanthracene, 9-methylanthracene, 2-ethylanthracene, 2-tert-butylanthracene, 2,6-di-tert-butylanthracene, and 9,10-diphenyl-2,6-di-tert-butylanthracene. Among these, from the viewpoint of compatibility with the photosensitive composition, it is preferable that the compound represented by the structure of formula (1) above includes 9,10-dibutoxyanthracene, 9,10-dipropoxyanthracene, 9,10-diethoxyanthracene, 9,10-bis(octanoyloxy)anthracene, etc.

[0029] Anthracene-based photosensitizer (B) may be synthesized by known methods, or a commercially available product may be used. For example, commercially available anthracene-based photosensitizer (B) products include "UVS-1331", "UVS-1101", "UVS-581", and "UVS-2171" manufactured by Air Water Performance Chemical Co., Ltd.

[0030] The anthracene-based photosensitizer (B) may be used alone or in combination of two or more types.

[0031] The content of the anthracene-based photosensitizer (B) is not particularly limited, as long as it does not impair the effect of high-precision patterning in the wavelength range of exposure of the DI according to this embodiment. For example, the content of the anthracene-based photosensitizer (B) is preferably 0.1 parts by mass or more and 3.0 parts by mass or less per 100 parts by mass of epoxy compound (A). If the content of the anthracene-based photosensitizer (B) is 0.1 parts by mass or more, the absorption of light in the wavelength range of exposure of the DI can be more reliably increased. If the content of the anthracene-based photosensitizer (B) is 3.0 parts by mass or less, the width of the bottom of the pattern (hereinafter also referred to as the "bottom pattern width") becomes excessively large compared to the width of the top of the pattern (hereinafter also referred to as the "top pattern width"). As a result, it is possible to prevent the pattern from becoming noticeably trapezoidal.

[0032] The content of the anthracene-based photosensitizer (B) is more preferably 0.2 parts by mass or more, even more preferably 0.3 parts by mass or more, and particularly preferably 0.4 parts by mass or more, per 100 parts by mass of epoxy compound (A). Furthermore, the content of the anthracene-based photosensitizer (B) is more preferably 2.8 parts by mass or less, even more preferably 2.5 parts by mass or less, and particularly preferably 2.0 parts by mass or less, per 100 parts by mass of epoxy compound (A).

[0033] [First photocationic polymerization initiator (C)] The resin composition according to this embodiment contains a first photocationic polymerization initiator (C). The first photocationic polymerization initiator (C) has a conjugate acid strength of HSbF ６ The polymerization initiator has a strength greater than or equal to and has a first anionic portion. By including the first photocationic polymerization initiator (C) in the resin composition, the photocuring of the resin composition can be advanced.

[0034] In this specification, "conjugate acid strength" refers to Hammett's acidity function H ０ This refers to the strength based on HSbF. ６ Hammett's acidity function H ０ It is -30. Therefore, in this specification, "(the first photocationic polymerization initiator (C)) has a conjugate acid strength of HSbF ６"equal to or greater than the strength of" means that the first photo cationic polymerization initiator (C) has an acidity function H of not more than the numerical value (-30). ０ On the other hand, in this specification, "(the second photo cationic polymerization initiator (D)) has a conjugate acid strength lower than that of HSbF ６ " means that the second photo cationic polymerization initiator (D) has an acidity function H higher than the numerical value (-30). ０

[0035] Specifically, the first photo cationic polymerization initiator (C) includes, for example, an ionic photoacid generator having (Rf) ｎ PF ６ － ｎ － , an ionic photoacid generator having (Rx) ｎ BX ４－ｎ － , an ionic photoacid generator having (Rx) ｎ GaX ４－ｎ － , and at least one ionic photoacid generator selected from the group consisting of HSbF ６ (antimony fluoride), etc.

[0036] In (Rf) ｎ PF ６－ｎ － , Rf is a perfluoroalkyl group and n is any number from 1 to 5. The number of carbon atoms of Rf in (Rf) ｎ PF ６－ｎ － is, for example, 1 or more and 3 or less, and when there are a plurality of Rf, they may be the same or different from each other.

[0037] In each of (Rx) ｎ BX ４－ｎ － and (Rx) ｎ GaX ４－ｎ － , Rx is a phenyl group in which part of the hydrogen atoms are substituted with halogen atoms or electron-withdrawing substituents. The halogen atom is a fluorine atom, a chlorine atom, a bromine atom, etc. The electron-withdrawing substituent is, for example, a trifluoromethyl group, a nitro group, a cyano group, etc. (Rx) ｎ ​BX ４－ｎ － and (Rx) ｎ GaX ４－ｎ － In each of them, X is a halogen atom, and a fluorine atom is preferred. (Rx) ｎ BX ４－ｎ － and (Rx) ｎ GaX ４－ｎ － In each of them, n is any number from 1 to 4. When there are multiple Rx, Rx may be the same as or different from each other. Examples of Rx include, for example, C ６ F ５ , (CF[[ID=了23]] ３ ) ２ C ６ H ３ , CF ３ C ６ H ４ C ６ H ３ F ２ etc. (Rx) ｎ Examples of BX ４－ｎ <000006了2>include, for example, (C ６ F ５ ) ４ B － , ((CF ３ ) ２ C ６ H ３ ) ４ B － , (CF ３ C ６ H ４ ) ４ B － , (C ６ F ５ ) ２ BF ２ － C ６ F ５ BF ３ － , (C ６ H ３ F ２ ) ４ B － etc.

[0038] Therefore, the "first anion part" of the first photo cationic polymerization initiator (C) means an anion part whose conjugate acid strength is equal to or greater than the strength of HSbF ６ . Specifically, the first anion part preferably includes at least one selected from the group consisting of B(C ６ F ５ ), Ga(C ４ － ), SbF ６ F ５ ), SbF ４ － , and PF ６ － (C ３ F ２ ). ５ ). ３ －

[0039] More specifically, the first photo cationic polymerization initiator (C) preferably includes at least one of the polymerization initiators represented by the following formulas (2) to (5).

[0040] [[ID=??]]

[0041]

[0042]

[0043] When the first photo cationic polymerization initiator (C) includes at least one of the polymerization initiators represented by the above formulas (2) to (5), the photocuring of the resin composition can proceed more reliably.

[0044] The first photo cationic polymerization initiator (C) may be synthesized by a known method or a commercial product may be used. For example, commercial products of the first photo cationic polymerization initiator (C) include "CPI-101A", "CPI-310FG", "CPI-310B", "CPI-410B", etc. manufactured by San-Apro Ltd., "Irgacure 290", etc. manufactured by BASF Japan Ltd., "ADEKA OPTOMER SP170", etc. manufactured by ADEKA Corporation, and the like.

[0045] The first photo cationic polymerization initiator (C) may be used alone or in combination of two or more. There seems to be a missing formula number in the provided text (line ID=35). I've translated it as best as possible with the given information. If you can provide the complete formula number, I can correct the translation.

[0046] The content of the first photocationic polymerization initiator (C) is not particularly limited, as long as it does not impair the effect of high-precision patterning in the wavelength range of exposure of the DI according to this embodiment. For example, the content of the first photocationic polymerization initiator (C) is preferably 0.1 parts by mass or more and 6.0 parts by mass or less per 100 parts by mass of epoxy compound (A). When the content of the first photocationic polymerization initiator (C) is 0.1 parts by mass or more, the photocuring of the resin composition can proceed well and the heat resistance can be increased. When the content of the first photocationic polymerization initiator (C) is 6.0 parts by mass or less, it is possible to suppress excessively large light loss at a wavelength of 1310 nm.

[0047] The content of the first photocationic polymerization initiator (C) is more preferably 0.2 parts by mass or more, even more preferably 0.3 parts by mass or more, and particularly preferably 0.5 parts by mass or more, per 100 parts by mass of epoxy compound (A). Furthermore, the content of the first photocationic polymerization initiator (C) is more preferably 5.0 parts by mass or less, even more preferably 4.0 parts by mass or less, and particularly preferably 3.0 parts by mass or less, per 100 parts by mass of epoxy compound (A).

[0048] [Second photocationic polymerization initiator (D)] The resin composition according to this embodiment contains one or more of the second photocationic polymerization initiator (D) and the benzotriazole-based ultraviolet absorber (E) described later. That is, the resin composition may contain either the second photocationic polymerization initiator (D) or the benzotriazole-based ultraviolet absorber (E), or it may contain both.

[0049] The second photocationic polymerization initiator (D) has a conjugate acid strength of HSbF ６This polymerization initiator has a lower strength than the first photocationic polymerization initiator (C) and has a second anionic portion. By including the second photocationic polymerization initiator (D) in the resin composition, patterning in the wavelength region of DI exposure becomes possible. Specifically, by including not only the first photocationic polymerization initiator (C) mentioned above but also the second photocationic polymerization initiator (D) in the resin composition, high-precision patterning in the wavelength region of DI exposure can be achieved.

[0050] The second photocationic polymerization initiator (D) is, for example, PF ６ － Ionic photoacid generator having BF ４ － Ionic photoacid generator having (Rf)SO ３ － It is preferable to include at least one ionic photoacid generator selected from the group consisting of an ionic photoacid generator having (Rf)SO4, and an ionic photoacid generator having sulfite ions. ３ － In this formula, Rf is a perfluoroalkyl group, and the number of carbon atoms in Rf is, for example, between 1 and 8.

[0051] Therefore, the "second anionic portion" of the second photocationic polymerization initiator (D) is defined as having a conjugate acid strength of HSbF ６ This refers to the anion portion whose strength is below that of PF. Specifically, the second anion portion is PF ６ － BF ４ － CF ３ SO ３ － ,CH ３ (C ６ H ４ ) SO ３ － , C ４ F ９ SO ３ － , R-SO ２ -N-SO ２ -R (R = alkyl skeleton), C(SO ２ -CF ３ ) ３ －Preferably, it includes at least one selected from the group consisting of , and camphor sulfonic acid.

[0052] More specifically, the second photocationic polymerization initiator (D) preferably contains at least one polymerization initiator represented by the structures of the following formulas (6) to (8).

[0053]

[0054]

[0055] If the second photocationic polymerization initiator (D) contains at least one polymerization initiator represented by the structures of formulas (6) to (8) above, patterning can be performed more reliably in the wavelength range of DI exposure.

[0056] The second photocationic polymerization initiator (D) may be synthesized by known methods, or a commercially available product may be used. For example, commercially available second photocationic polymerization initiators (D) include "CPI-110P" and "CPI-100P" from Sunapro Co., Ltd., "Omnicat 250" and "Omnicat 270" from IGM Resins B.V., and "WPAG-145," "WPAG-149," "WPAG-170," "WPAG-199," "WPAG-336," "WPAG-367," "WPAG-370," "WPAG-469," and "WPAG-638" from Fujifilm Wako Co., Ltd.

[0057] The second photocationic polymerization initiator (D) may be used alone or in combination of two or more types.

[0058] The content of the second photocationic polymerization initiator (D) is not particularly limited, as long as it does not impair the effect of high-precision patterning in the wavelength region of DI exposure according to this embodiment. For example, the content of the second photocationic polymerization initiator (D) is preferably 0.1 parts by mass or more and 2.0 parts by mass or less per 100 parts by mass of epoxy compound (A). If the content of the second photocationic polymerization initiator (D) is 0.1 parts by mass or more, patterning in the wavelength region of DI exposure can be performed more reliably. If the content of the second photocationic polymerization initiator (D) is 2.0 parts by mass or less, it is possible to prevent the lower pattern width from becoming excessively large compared to the upper pattern width, which would cause the pattern to become noticeably trapezoidal.

[0059] The content of the second photocationic polymerization initiator (D) is more preferably 0.2 parts by mass or more, even more preferably 0.3 parts by mass or more, and particularly preferably 0.5 parts by mass or more, per 100 parts by mass of epoxy compound (A). Furthermore, the content of the second photocationic polymerization initiator (D) is more preferably 1.8 parts by mass or less, even more preferably 1.5 parts by mass or less, and particularly preferably 1.0 part by mass or less, per 100 parts by mass of epoxy compound (A).

[0060] [Benzotriazole-based UV absorber (E)] As described above, the resin composition according to this embodiment contains one or more of the second photocationic polymerization initiator (D) and the benzotriazole-based UV absorber (E) described above. By including the benzotriazole-based UV absorber (E) in the resin composition, the upper pattern width and the lower pattern width tend to be the same in the wavelength range of DI exposure, enabling patterning with excellent accuracy.

[0061] In particular, when the resin composition contains both the second photocationic polymerization initiator (D) and the benzotriazole-based ultraviolet absorber (E) mentioned above, the upper and lower pattern widths tend to become even more similar, enabling patterning with superior accuracy. In other words, the trapezoidalization index of the pattern, calculated from the ratio of the upper pattern width to the lower pattern width, can be made close to 1.

[0062] The benzotriazole-based ultraviolet absorber (E) is not particularly limited, but for example, a benzotriazole-based ultraviolet absorber having one benzotriazole skeleton in one molecule can be used. This benzotriazole-based ultraviolet absorber having one benzotriazole skeleton in one molecule may be synthesized by known methods or a commercially available product may be used.

[0063] Examples of such benzotriazole-based UV absorbers (E) include 2-(2H-benzotriazole-2-yl)-6-(1-methyl-1-phenylethyl)-4-(1,1,3,3-tetramethylbutyl)phenol ("Tinuvin 928" manufactured by BASF Japan Ltd.), 2-(2-hydroxy-5-tert-butylphenyl)-2H-benzotriazole ("Tinuvin P" manufactured by BASF Japan Ltd.), benzenepropanoic acid and 3-(2H-benzotriazole-2-yl)-5-(1,1-dimethylethyl)-4-hydroxy(C7-9 side chain and linear alkyl) ester compounds ("Tinuvin 384-2" manufactured by BASF Japan Ltd.), and 2-(2H-benzotriazole-2-yl)-4,6-bis(1-methyl-1-phenylethyl)phenol ("Tinuvin P" manufactured by BASF Japan Ltd.) 900"), 2-(2H-benzotriazole-2-yl)-6-(1-methyl-1-phenylethyl)-4-(1,1,3,3-tetramethylbutyl)phenol (BASF Japan Ltd.'s "Tinuvin 928"), reaction product of methyl-3-(3-(2H-benzotriazole-2-yl)-5-t-butyl-4-hydroxyphenyl)propionate / polyethylene glycol 300 (BASF Japan Ltd.'s "Tinuvin 1130"), 2-(2H-benzotriazole-2-yl)-p-cresol (BASF Japan Ltd.'s "Tinuvin P"), 2(2H-benzotriazole-2-yl)-4-6-bis(1-methyl-1-phenylethyl)phenol (BASF Japan Ltd.'s "Tinuvin 234"), 2-[5-chloro(2H)-benzotriazole-2-yl]-4-methyl-6-(tert-butyl)phenol ("Tinuvin 326" manufactured by BASF Japan Ltd.), 2-(2H-benzotriazole-2-yl)-4,6-di-tert-pentylphenol ("Tinuvin 328" manufactured by BASF Japan Ltd.), 2-(2H-benzotriazole-2-yl)-4-(1,1,3,Examples include 3-tetramethylbutyl)phenol ("Tinuvin 329" manufactured by BASF Japan Ltd.), the reaction product of methyl 3-(3-(2H-benzotriazole-2-yl)-5-tert-butyl-4-hydroxyphenyl)propionate and polyethylene glycol 300 ("Tinuvin 213" manufactured by BASF Japan Ltd.), 2-(2H-benzotriazole-2-yl)-6-dodecyl-4-methylphenol ("Tinuvin 571" manufactured by BASF Japan Ltd.), and 2-[2-hydroxy-3-(3,4,5,6-tetrahydrophthalimidomethyl)-5-methylphenyl]benzotriazole ("Sumisorb 250" manufactured by Sumitomo Chemical Co., Ltd.).

[0064] More specifically, the benzotriazole-based ultraviolet absorber (E) preferably includes a compound represented by the structure of the following formula (9).

[0065] When the benzotriazole-based ultraviolet absorber (E) contains a compound represented by the structure of formula (9) above, patterning with greater reliability and precision can be achieved in the wavelength range of DI exposure.

[0066] Benzotriazole-based ultraviolet absorbers (E) may be used individually or in combination of two or more types.

[0067] The content of the benzotriazole-based ultraviolet absorber (E) is not particularly limited, as long as it does not impair the effect of high-precision patterning in the wavelength range of exposure of the DI according to this embodiment. For example, the content of the benzotriazole-based ultraviolet absorber (E) is preferably 0.1 parts by mass or more and 2.0 parts by mass or less per 100 parts by mass of epoxy compound (A). When the content of the benzotriazole-based ultraviolet absorber (E) is 0.1 parts by mass or more, patterning with better accuracy can be performed more reliably in the wavelength range of exposure of the DI. When the content of the benzotriazole-based ultraviolet absorber (E) is 2.0 parts by mass or less, it is possible to suppress an excessive drop in the glass transition temperature of the cured product and a significant decrease in heat resistance.

[0068] The content of the benzotriazole-based ultraviolet absorber (E) is more preferably 0.2 parts by mass or more, even more preferably 0.3 parts by mass or more, and particularly preferably 0.5 parts by mass or more, per 100 parts by mass of epoxy compound (A). Furthermore, the content of the benzotriazole-based ultraviolet absorber (E) is more preferably 1.8 parts by mass or less, even more preferably 1.5 parts by mass or less, and particularly preferably 1.0 part by mass or less, per 100 parts by mass of epoxy compound (A).

[0069] [Ratio of each component content] In the resin composition according to this embodiment, the ratio of the content of the anthracene-based photosensitizer (B) to the content of the first photocationic polymerization initiator (C) is preferably 30% or more and 250% or less. When the ratio of the content of the anthracene-based photosensitizer (B) to the content of the first photocationic polymerization initiator medium (C) is within this range, a resin composition with a suitable balance in terms of both patterning accuracy and heat resistance in the wavelength range of DI exposure can be obtained.

[0070] The ratio of the content of the anthracene-based photosensitizer (B) to the content of the first photocationic polymerization initiator (C) is more preferably 35% to 230%, even more preferably 40% to 200%, and particularly preferably 50% to 150%.

[0071] Furthermore, in the resin composition according to this embodiment, the ratio of the content of the second photocationic polymerization initiator (D) to the content of the first photocationic polymerization initiator (C) is preferably 10% or more and 150% or less. When the ratio of the content of the second photocationic polymerization initiator (D) to the content of the first photocationic polymerization initiator (C) is within this range, a resin composition with a suitable balance in terms of both patterning accuracy and heat resistance in the wavelength range of DI exposure can be obtained.

[0072] The ratio of the content of the second photocationic polymerization initiator (D) to the content of the first photocationic polymerization initiator (C) is more preferably 13% to 140%, even more preferably 15% to 130%, and particularly preferably 20% to 100%.

[0073] [Other Additives] In addition to the components described above, the resin composition may further contain other additives such as antioxidants, leveling agents, coupling agents (silane coupling agents), flame retardants, and inorganic fillers, as long as they do not impair the effect of high-precision patterning in the wavelength range of DI exposure according to this embodiment.

[0074] In particular, from the viewpoint of improving the heat resistance of the optical waveguide, the resin composition preferably further contains an antioxidant. The antioxidant is not particularly limited, and phenolic antioxidants, phosphite antioxidants, sulfur-based antioxidants, etc., can be used. Of these, a phenolic antioxidant is preferred.

[0075] Commercially available phenolic antioxidants can be used. Examples of commercially available phenolic antioxidants include "AO-20," "AO-30," "AO-40," "AO-50," "AO-60," and "AO-80" from ADEKA Corporation, and "SUMILIZER GA-80" from Sumitomo Chemical Co., Ltd.

[0076] The antioxidant content is not particularly limited, but is preferably (0% by mass or more) 5% by mass or less, and more preferably (0% by mass or more) 1% by mass or less, per 100 parts by mass of epoxy compound (A).

[0077] Thus, the resin composition for optical waveguides according to this embodiment can perform high-precision patterning in the wavelength range of DI exposure. Therefore, by using the resin composition for optical waveguides according to this embodiment to perform DI exposure and manufacture optical waveguides, it is possible to obtain optical waveguides with improved patterning accuracy and stable quality, and the yield can also be significantly improved.

[0078] 2. Resin-coated film or dry film The resin-coated film according to this embodiment is not particularly limited as long as it has a layer containing an uncured or semi-cured portion of the optical waveguide resin composition according to the above embodiment (hereinafter also referred to as the "optical waveguide resin composition layer" or "resin composition layer") and a support film.

[0079] In this specification, "semi-cured product" means a resin composition in which a liquid material containing a varnish-like resin composition, as described later, has been applied, and subsequently heated, dried, and irradiated with light, such as ultraviolet light, at an appropriate temperature and time as necessary, and the resin has partially cured and is in a state in which further curing is possible. Furthermore, in this specification, "uncured product" means a resin composition in which it has been heated and dried at an appropriate temperature and time as necessary, and the resin has not yet cured. In other words, both "uncured product" and "semi-cured product" are in a state in which the resin components in the resin composition can further cure.

[0080] Furthermore, in this specification, "cured product" refers to a resin layer in which the curing reaction of an uncured or semi-cured resin composition layer proceeds by irradiation with light such as ultraviolet light, and the resin becomes crosslinked, resulting in a resin layer that does not melt even when heated. In the embodiments described later, the optical waveguide finally obtained comprises a core portion and / or cladding portion which are cured products of the optical waveguide resin composition.

[0081] A resin-coated film may, for example, have a support film on at least one surface of the resin composition layer. Furthermore, a protective film may be laminated on the other surface of the resin composition layer. In addition, a resin-coated film may include other layers besides the resin composition layer, the support film, and an optional protective film.

[0082] The support film is not particularly limited, but examples include polyethylene terephthalate (PET) film, biaxially oriented polypropylene film, polyethylene naphthalate film, and polyimide film. Of these, PET film is preferred. The protective film is not particularly limited, but examples include polypropylene film.

[0083] The method for manufacturing the resin-coated film is not particularly limited, but examples include the method described below. First, a solvent or the like is added to the optical waveguide resin composition according to the above embodiment to prepare a varnish-like liquid material containing the optical waveguide resin composition. Next, the prepared liquid material is applied onto a support film. This application can be done using a comma coater or the like. After that, the applied liquid material is dried at an appropriate temperature and time, and if necessary, irradiated with light such as ultraviolet light to form a layer on the support film containing an uncured material of the optical waveguide resin composition or a semi-cured material of the uncured material of the optical waveguide resin composition (i.e., a "resin composition layer"). Furthermore, a protective film may be laminated on this resin composition layer. Examples of methods for laminating the protective film include thermal lamination.

[0084] The dry film according to this embodiment is not particularly limited as long as it has a layer containing the uncured or semi-cured material of the optical waveguide resin composition according to the above embodiment (i.e., an "optical waveguide resin composition layer" or "resin composition layer").

[0085] The dry film may include a film substrate made of the same material as the support film described above, and / or the protective film and / or other layers described above, on at least one surface and / or the other surface of the resin composition layer. Alternatively, the dry film may consist only of the resin composition layer.

[0086] The method for manufacturing the dry film is not particularly limited, and for example, it can be manufactured by the same method as the method for manufacturing the resin-coated film described above.

[0087] The dry film according to this embodiment is exposed to a high-pressure mercury lamp at a rate of 2000 mJ / cm². ２ It is preferable that the arithmetic mean roughness (Ra) of the unexposed pattern bottom surface is 0.4 μm or less after pattern exposure at a light intensity, followed by heating at 150°C for 10 minutes, immersion in a cyclopentanone:water mixture with a mass ratio of 96:4 at 25°C for 1 minute, and drying at 120°C for 10 minutes. If the dry film has an arithmetic mean roughness (Ra) of 0.4 μm or less after such treatment, the wall surface roughness after curing will be less, and it will have good surface smoothness, which is expected to ultimately lead to a reduction in light loss at a wavelength of 1310 nm. Furthermore, in the resin-coated film according to this embodiment, the resin composition layer is subjected to heating with a high-pressure mercury lamp at 2000 mJ / cm². ２ It is preferable that the arithmetic mean roughness (Ra) of the unexposed pattern bottom surface is 0.4 μm or less after pattern exposure at a light intensity, followed by heat treatment at 150°C for 10 minutes, immersion in a cyclopentanone:water mixture with a mass ratio of 96:4 at 25°C for 1 minute, and drying at 120°C for 10 minutes.

[0088] In this specification, "arithmetic mean roughness (Ra) (of the surface of the processed film)" means the arithmetic mean roughness (Ra) of the unexposed bottom surface of the developed film, measured using "HYBRID" manufactured by Lasertec Corporation.

[0089] The arithmetic mean roughness (Ra) of the surface of the film after such treatment is more preferably 0.3 μm or less, even more preferably 0.25 μm or less, and particularly preferably 0.2 μm or less. The lower limit of the arithmetic mean roughness (Ra) of the surface of the film after treatment is not particularly limited and may be 0 μm or more.

[0090] The resin-coated film and dry film containing the resin composition layer manufactured in this manner are used as materials for optical waveguides according to the embodiments described later. The resin-coated film and dry film may be used when manufacturing the core portion of the optical waveguide or when manufacturing the cladding portion. However, the core portion requires more precise patterning than the cladding portion. Therefore, the resin-coated film and dry film according to this embodiment can be suitably used in particular for manufacturing the core portion of an optical waveguide.

[0091] 3. Liquid Material The liquid material according to this embodiment includes the resin composition for optical waveguides according to the above embodiment.

[0092] Specifically, the liquid material is, as described above, a varnish-like resin composition for optical waveguides according to the aforementioned embodiment, which contains a solvent as needed. The solvent is not particularly limited, as long as it is a solvent for any resin known to those skilled in the art. For example, examples of solvents include methyl ethyl ketone, toluene, xylene, gamma butyrolactone, acetone, methyl isobutyl ketone, cyclohexanone, propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, ethyl acetate, butyl acetate, ethyl lactate, N,N-dimethylformamide, dimethylacetamide, dimethyl sulfoxide, N-methyl-2-pyrrolidone, and the like.

[0093] According to this embodiment, the liquid material can be used directly in the manufacture of an optical waveguide, preferably the core, without going through a film formation process, as a material for the core or cladding of the optical waveguide. Furthermore, it can also be used directly as a material for the insulating layer of the optical waveguide.

[0094] 4. Optical waveguide and method for manufacturing the same The optical waveguide according to this embodiment is formed using the resin composition, dry film, resin-coated film, and / or liquid material according to the above embodiment. Therefore, by developing with DI exposure, a high-precision core portion and / or cladding portion can be formed.

[0095] Specifically, the optical waveguide according to this embodiment comprises a core portion and a cladding portion having a lower refractive index than the core portion and formed to cover the core portion, wherein the core portion or the cladding portion is formed using the resin composition or dry film (or a resin composition layer of a resin-coated film) according to the above embodiment. As described above, it is preferable that the core portion of the optical waveguide is formed using the resin composition or dry film (or a resin composition layer of a resin-coated film) according to the above embodiment.

[0096] In this specification, "the clad portion is formed to cover the core portion" means that the underclad and / or overclad, formed by curing a dry clad film or the like, is formed to embed the core portion (or substantially cover or surround the core portion).

[0097] Hereinafter, an example of a method for forming an optical waveguide on a substrate using the dry film according to the above embodiment will be described with reference to Figure 1. In Figures 1(a) to 1(f), each reference numeral indicates the cladding dry film 1, the core dry film 2, the cladding portion 3, the undercladding 3a, the overcladding 3b, the core portion 4, the substrate 10, the electrical circuit 11, and the optical waveguide A, respectively.

[0098] In the example shown in Figure 1, a dry film for cladding and a dry film for the core are used to form the core and cladding portions of the optical waveguide, respectively. In the example shown in Figure 1, the dry film according to the above embodiment is used as the dry film for the core, and a dry film with a lower refractive index than the core film is used as the dry film for cladding. The dry film according to the above embodiment may be used for both the dry film for cladding and the dry film for the core.

[0099] First, as shown in Figure 1(a), a dry cladding film 1 is laminated onto the surface of a substrate 10 on which the electrical circuit 11 is formed. Then, the dry cladding film 1 is cured by light irradiation such as ultraviolet light, heating, etc. As the substrate 10, for example, a flexible printed circuit board with an electrical circuit formed on one side of a transparent substrate such as a polyimide film, or a printed circuit board such as glass epoxy, can be used. Through this process, an undercladding 3a is laminated onto the surface of the substrate 10, as shown in Figure 1(b).

[0100] Next, as shown in Figure 1(c), after laminating the core dry film 2 onto the surface of the underclad 3a, a DI exposure apparatus or the like is used to scan a laser beam along the core pattern shape and directly draw the core pattern onto the core dry film 2.

[0101] After exposure, the core dry film 2 is developed using a developer containing an organic solvent and water to remove the uncured resin from the unexposed portion of the core dry film 2. It is preferable to use a mixed solution containing an organic solvent and water as the developer. Developing with such a mixed solution effectively suppresses light loss at a wavelength of 1310 nm.

[0102] The organic solvent is not particularly limited, but examples include toluene, methyl ethyl ketone (MEK), propylene glycol methyl ether acetate (PGMEA), propylene glycol monomethyl ether (PGME), acetone, a mixture of dipropylene glycol dimethyl ether and naphtha (DS2100), N-methyl-2-pyrrolidone (NMP), and cyclopentanone.

[0103] Furthermore, the mass ratio of the organic solvent to water in the mixed solution used as a developer (organic solvent:water) is preferably 99.5:0.5 to 70:30, more preferably 99:1 to 80:20, and even more preferably 98:2 to 85:15.

[0104] After development, as shown in Figure 1(d), a core portion 4 with a predetermined core pattern is formed on the surface of the underclad 3a.

[0105] Next, as shown in Figure 1(e), the cladding dry film 1 is laminated to cover the undercladding 3a and the core portion 4. Then, by curing the cladding dry film 1 by light irradiation, heating, etc., the overcladding 3b shown in Figure 1(f) is laminated and formed. In this way, an optical waveguide A is formed on the surface of the substrate 10, in which the core portion 4 is embedded within the cladding portion 3 consisting of the undercladding 3a and the overcladding 3b.

[0106] The optical waveguide A obtained in this way has a core portion that is patterned with high precision because the dry film according to the above embodiment is used as the core dry film. Therefore, the substrate 10 on which such an optical waveguide A is formed is preferably used as a printed circuit board for optical transmission, and is preferably used in, for example, switches in data centers, high-performance computing (HPC) mobile phones, and personal information terminals.

[0107] As described above, this specification discloses various aspects of technology, the main technologies among them are summarized below.

[0108] A resin composition for optical waveguides according to a first aspect of the present invention comprises an epoxy compound (A), an anthracene-based photosensitizer (B), a first photocationic polymerization initiator (C), and one or more of a second photocationic polymerization initiator (D) and a benzotriazole-based ultraviolet absorber (E), wherein the first photocationic polymerization initiator (C) has a conjugate acid strength of HSbF ６ A polymerization initiator having a strength greater than or equal to HSbF, and having a first anion portion, wherein the second photocationic polymerization initiator (D) has a conjugate acid strength of HSbF ６ This polymerization initiator has a strength lower than that of the first one and has a second anionic portion.

[0109] A second aspect of the present invention is a resin composition for optical waveguides according to the first aspect, wherein the anthracene-based photosensitizer (B) comprises a compound represented by the structure of formula (1) above. In formula (1), R １ Each of these is an alkyl group having 1 to 10 carbon atoms.

[0110] A third aspect of the present invention is a resin composition for optical waveguides according to the first or second aspect of the present invention, wherein the first anion portion is B(C ６ F ５ ) ４ － Ga(C) ６ F ５ ) ４ － SbF ６ － , and PF ３ (C ２ F ５ ) ３ － It includes at least one selected from the group consisting of the following.

[0111] A fourth aspect of the present invention is a resin composition for optical waveguides according to any one of the first to third aspects of the present invention, wherein PF ６ － BF ４ － CF ３ SO ３ － ,CH ３ (C ６ H ４ ) SO ３ － , C ４ F ９ SO ３ － , R-SO ２ -N-SO ２ -R (R = alkyl skeleton), C(SO ２ -CF ３ ) ３ － The compound comprises at least one selected from the group consisting of camphor sulfonic acid.

[0112] A fifth aspect of the present invention is a resin composition for optical waveguides according to any of the first to fourth aspects, wherein the first photocationic polymerization initiator (C) comprises at least one polymerization initiator represented by the structures of formulas (2) to (5) above.

[0113] A resin composition for optical waveguides according to a sixth aspect of the present invention is a resin composition for optical waveguides according to any of the first to fifth aspects, wherein the second photocationic polymerization initiator (D) comprises at least one polymerization initiator represented by the structures of formulas (6) to (8) above.

[0114] The seventh aspect of the present invention is an optical waveguide resin composition according to any of the first to sixth aspects, wherein the benzotriazole compound (E) includes a compound represented by the structure of (9) above.

[0115] The eighth aspect of the present invention is an optical waveguide resin composition according to any of the first to seventh aspects, wherein the content of the anthracene-based photosensitizer (B) is 0.1 parts by mass or more and 3.0 parts by mass or less per 100 parts by mass of epoxy compound (A).

[0116] The ninth aspect of the present invention is an optical waveguide resin composition according to any of the first to eighth aspects, wherein the content of the first photocationic polymerization initiator (C) is 0.1 parts by mass or more and 6.0 parts by mass or less per 100 parts by mass of epoxy compound (A).

[0117] The resin composition for optical waveguides according to the tenth aspect of the present invention is a resin composition for optical waveguides according to any one of the first to ninth aspects, wherein the content of the second photocationic polymerization initiator (D) is 0.1 parts by mass or more and 2.0 parts by mass or less per 100 parts by mass of epoxy compound (A).

[0118] The eleventh aspect of the present invention is an optical waveguide resin composition according to any of the first to tenth aspects, wherein the content of the benzotriazole-based ultraviolet absorber (E) is 0.1 parts by mass or more and 2.0 parts by mass or less per 100 parts by mass of the epoxy compound (A).

[0119] The optical waveguide resin composition according to the twelfth aspect of the present invention is an optical waveguide resin composition according to any one of the first to eleventh aspects, wherein the ratio of the content of anthracene-based photosensitizer (B) to the content of a first photocationic polymerization initiator (C) is 30% or more and 250% or less.

[0120] The optical waveguide resin composition according to the thirteenth aspect of the present invention is an optical waveguide resin composition according to any of the first to twelfth aspects, wherein the ratio of the content of the second photocationic polymerization initiator (D) to the content of the first photocationic polymerization initiator (C) is 10% or more and 150% or less.

[0121] A resin composition for optical waveguides according to the 14th aspect of the present invention is a resin composition for optical waveguides according to any of the 1st to 13th aspects, wherein the epoxy compound (A) comprises a bisphenol A type epoxy compound.

[0122] The optical waveguide resin composition according to the 15th aspect of the present invention is an optical waveguide resin composition according to any of the 1st to 14th aspects, wherein the epoxy compound (A) comprises two or more bisphenol A type epoxy compounds with different melting points.

[0123] A dry film according to the sixteenth aspect of the present invention has a layer containing an uncured or semi-cured optical waveguide resin composition according to any of the first to fifteenth aspects.

[0124] A dry film according to the 17th aspect of the present invention is a dry film according to the 16th aspect, wherein the pressure at 2000 mJ / cm² under a high-pressure mercury lamp is... ２ After pattern exposure at a light intensity, the sample is heated at 150°C for 10 minutes, immersed in a cyclopentanone:water mixture with a mass ratio of 96:4 at 25°C for 1 minute, and dried at 120°C for 10 minutes. The arithmetic mean roughness (Ra) of the unexposed pattern bottom surface is 0.4 μm or less.

[0125] A resin-coated film according to the 18th aspect of the present invention comprises a layer containing an uncured or semi-cured optical waveguide resin composition according to any of the first to 15 aspects, and a support film.

[0126] A resin-coated film according to the 19th aspect of the present invention is a resin-coated film according to the 18th aspect, wherein a layer containing an uncured or semi-cured material of the optical waveguide resin composition is heated to 2000 mJ / cm with a high-pressure mercury lamp. ２After pattern exposure at a light intensity, the sample is heated at 150°C for 10 minutes, immersed in a cyclopentanone:water mixture with a mass ratio of 96:4 at 25°C for 1 minute, and dried at 120°C for 10 minutes. The arithmetic mean roughness (Ra) of the unexposed pattern bottom surface is 0.4 μm or less.

[0127] The liquid material according to the 20th aspect of the present invention includes a resin composition for optical waveguides according to any of the first to 15 aspects.

[0128] An optical waveguide according to the 21st aspect of the present invention is an optical waveguide comprising a core portion and a cladding portion having a lower refractive index than the core portion and formed to cover the core portion, wherein the core portion is formed using an optical waveguide resin composition according to any of the 1st to 15th aspects (or an uncured material of the optical waveguide resin composition of a dry film according to the 16th to 17th aspects, a resin-coated film according to the 18th to 19th aspects, or a layer containing a semi-cured material of the optical waveguide resin composition, or a liquid material according to the 20th aspect).

[0129] A method for manufacturing an optical waveguide according to a 22nd aspect of the present invention is a method for manufacturing an optical waveguide according to a 21st aspect, which includes developing using a mixed solution containing an organic solvent and water.

[0130] The present invention will be described in more detail below with reference to examples, but the present invention is not limited in any way by these examples.

[0131] First, the raw materials used to prepare the optical waveguide resin composition in this embodiment are summarized below.

[0132] [Epoxy Compounds (A)] ・BisA type epoxy compound 1: Polyfunctional epoxy compound, manufactured by Printec Co., Ltd., epoxy equivalent 210 g / eq, "VG3101M80" ・BisA type epoxy compound 2: Liquid bisphenol A type epoxy compound, manufactured by DIC Corporation, epoxy equivalent 184 g / eq to 194 g / eq, "850S" ・BisA type epoxy compound 3: Solid bisphenol A type epoxy compound, manufactured by Mitsubishi Chemical Corporation, epoxy equivalent 450 g / eq to 500 g / eq, "1001" ・BisA type epoxy compound 4: Solid bisphenol A type epoxy compound, manufactured by Mitsubishi Chemical Corporation, epoxy equivalent 900 g / eq to 1100 g / eq, "1006FS"

[0133] [Anthracene-based photosensitizer (B)] 9,10-Dibutoxyanthracene (Air Water Performance Chemicals Inc., "UVS-1331") (a compound represented by the structure of formula (10) below)

[0134] [First photocationic polymerization initiator (C)] ・First photocationic polymerization initiator 1: "CPI-101A" manufactured by Sunapro Co., Ltd. (polymerization initiator represented by the structure of formula (2) above) ・First photocationic polymerization initiator 2: "CPI-310FG" manufactured by Sunapro Co., Ltd. (polymerization initiator represented by the structure of formula (3) above) ・First photocationic polymerization initiator 3: "CPI-310B" manufactured by Sunapro Co., Ltd. (polymerization initiator represented by the structure of formula (4) above) ・First photocationic polymerization initiator 4: "CPI-410B" manufactured by Sunapro Co., Ltd. (polymerization initiator represented by the structure of formula (5) above)

[0135] [Second photocationic polymerization initiator (D)] "CPI-110P" manufactured by Sunapro Co., Ltd. (polymerization initiator represented by the structure of formula (6) above)

[0136] [Benzotriazole-based UV absorber (E)] "TinuvinP" (polymerization initiator represented by the structure of formula (9) above), manufactured by BASF Japan Ltd.

[0137] 1. Evaluation Tests In these evaluation tests, various resin compositions for optical waveguides were prepared using epoxy compounds (A), anthracene-based photosensitizers (B), a first photocationic polymerization initiator (C), a second photocationic polymerization initiator (D), and a benzotriazole-based ultraviolet absorber (E), with varying ratios of these components. Subsequently, as part of the evaluation tests, dry films were manufactured using these resin compositions, and their patterning properties in the DI wavelength range were evaluated.

[0138] First, the methods for preparing the optical waveguide resin composition (resin varnish), the method for manufacturing the dry film (core dry film), and the method for manufacturing the cladding dry film used in common in each example and comparative example will be described in detail below.

[0139] <Method for preparing optical waveguide resin compositions (resin varnishes)> In each example and comparative example, the components were blended according to the formulations (parts by mass) shown in Tables 1 and 2 below, and the mixed solvent of MEK and toluene was adjusted to 60 parts by mass per 100 parts by mass of the total epoxy compound. These were then mixed while heating to 50°C to 80°C. Next, the mixture was filtered through a membrane filter with a pore size of 0.2 μm, and then degassed to prepare the optical waveguide resin compositions (resin varnishes) for Examples 1 to 16 and Comparative Examples 1 to 3.

[0140] <Method for Manufacturing Dry Film (Dry Film for Core)> The optical waveguide resin compositions (resin varnishes) prepared by the method described above for each example and comparative example were applied to PET film (product number A4160) manufactured by Toyobo Co., Ltd. using a comma coater head multi-coater manufactured by Hirano Techseed Co., Ltd. The PET film was then dried at 130°C for 10 minutes to a predetermined thickness, and a release film, OPP-MA420 manufactured by Oji Specialty Paper Co., Ltd., was heat-laminated to obtain a dry film with a thickness of approximately 5 μm. The obtained dry films were used as the core dry films for each example and comparative example.

[0141] <Method for Manufacturing Cladding Dry Film> Cladding dry films for each example and comparative example of waveguide samples were manufactured by the following method. As the base epoxy compound for the cladding dry film, an F-containing epoxy compound ("YX7760", manufactured by Mitsubishi Chemical Corporation) was used. Specifically, first, 100 parts by mass of the F-containing epoxy compound was mixed with 1 part by mass of a photocationic curing agent ("CPI-101A", manufactured by Sunapro Co., Ltd.) and 1 part by mass of a phenolic antioxidant ("AO-60", manufactured by ADEKA Corporation). The mixture of MEK and toluene was adjusted to 55 parts by mass per 100 parts by mass of the F-containing epoxy compound, and these were mixed while heating to 50°C to 80°C. After that, the mixture was filtered through a 1.0 μm pore size membrane filter made of polytetrafluoroethylene (PTFE), and then degassed to prepare a resin varnish. The prepared resin varnish was applied to a PET film (product number A4100) manufactured by Toyobo Co., Ltd. using a multi-coater with a comma coater head manufactured by Hirano Texseed Co., Ltd. The film was then dried to obtain a 20 μm thick dry cladding film.

[0142] Next, using the dry films (core dry films) of each example and comparative example manufactured by the method described above, as well as the common cladding dry film, patterning properties were evaluated using the following method.

[0143] <Evaluation Test of Patterning Properties in the Wavelength Range of DI Exposure> The patterning properties in the wavelength range of DI exposure were evaluated by the following method. Specifically, the evaluation was performed by forming cores on the underclad using the core dry film for each example and comparative example and the common cladding dry film manufactured by the method described above.

[0144] First, the cladding dry film was laminated onto the substrate using a vacuum laminator "V-130" at 65°C and 0.3 MPa. Then, it was subjected to ultra-high pressure mercury lamp treatment at 2 J / cm². ２The dry cladding film was irradiated with ultraviolet light at a light intensity of [specify intensity]. After irradiation, the release film was peeled off the dry cladding film, and it was heat-treated at 160°C for 30 minutes to harden the dry cladding film and form the undercladding.

[0145] Subsequently, the core dry films for each example and comparative example were laminated onto the underclad surface using a vacuum laminator "V-130" in the same manner and under the same conditions as described above. After peeling off the release film from the core dry film, a core pattern with a width of 5 μm was formed by exposure using a maskless aligner ("MLA150", manufactured by Heidelberg Instruments Co., Ltd.) under the following conditions: (Exposure conditions) Light source: 375 nm laser Exposure amount: 8000 mJ / cm ２ • Drawing pattern: L / S = 5 μm / 250 μm • Length: 5 cm

[0146] Subsequently, the exposed film was heat-treated at 150°C for 10 minutes. Next, the unexposed portions of the dry film were dissolved and removed by developing with a cyclopentanone:water mixture in a mass ratio of 96:4. After dissolution and removal, the core portion was washed with water, air-blown, and dried at 120°C for 10 minutes to form the core.

[0147] Finally, the shape of the formed core, specifically the upper pattern width (μm) and lower pattern width (μm) of the core, was measured using a confocal microscope ("HYBRID," manufactured by Lasertec Corporation). Furthermore, the ratio of the upper pattern width to the lower pattern width was calculated as a trapezoidal index of the core pattern. Patternability was evaluated based on these measured and calculated values. The measured values ​​for the upper and lower pattern widths of the core were the average values ​​obtained by randomly measuring five locations. The evaluation criteria for patternability in the wavelength range of DI exposure are shown below. If the material was uncured, the evaluation was considered a failure. Evaluation Criteria: Pass: Measured upper pattern width is 5 μm or more and 6 μm or less, and trapezoidal index is 0.60 or more and 1.0 or less. Fail: Measured upper pattern width is less than 5 μm or more than 6 μm, or trapezoidal index is less than 0.60 or greater than 1.0.

[0148] The measurement and evaluation results of the patterning properties in the wavelength range of DI exposure for each of the above examples and comparative examples are summarized in Tables 1 and 2 below, along with the core composition. In the "-" column of the core composition in Tables 1 and 2 below, "-" indicates that it is not included in the resin composition of that core.

[0149]

[0150]

[0151] <Discussion> As shown in Tables 1 and 2 above, the resin compositions of Examples 1 to 13 were able to achieve highly accurate patterning in the wavelength range of DI exposure. This is thought to be because each resin composition contained one or more of the following: epoxy compound (A), anthracene-based photosensitizer (B), first photocationic polymerization initiator (C), second photocationic polymerization initiator (D), and benzotriazole-based ultraviolet absorber (E).

[0152] In particular, the resin compositions of Examples 3, 4, 7, 9, 11, and 13 had trapezoidalization indices close to 1.0, enabling more precise patterning. This is thought to be influenced by whether or not the resin composition contains both the second photocationic polymerization initiator (D) and the benzotriazole-based ultraviolet absorber (E), the type of first photocationic polymerization initiator (C) contained in the resin composition, the ratio (%) of the anthracene-based photosensitizer (B) to the content of the first photocationic polymerization initiator (C), and the ratio (%) of the second photocationic polymerization initiator (D) to the content of the first photocationic polymerization initiator (C). In particular, when the resin composition contained both the second photocationic polymerization initiator (D) and the benzotriazole-based ultraviolet absorber (E), there was a tendency for more precise patterning to be possible in the wavelength range of DI exposure.

[0153] The resin composition of Comparative Example 1 did not contain an anthracene-based photosensitizer (B), and therefore could not be cured, and thus could not form a dry film.

[0154] The resin compositions of Comparative Examples 2 and 3 exhibited a large pattern width on the formed core and poor patterning accuracy in the DI exposure wavelength range. This is thought to be because, although the resin compositions contained an anthracene-based photosensitizer (B), they did not contain either the second photocationic polymerization initiator (D) or the benzotriazole-based ultraviolet absorber (E).

[0155] 2. Reference Evaluation Tests Using the dry films (core dry films) of each example manufactured by the method described above, reference evaluation tests were conducted for curability (presence or absence of tack), glass transition temperature, light loss at a wavelength of 1310 nm, and the arithmetic mean surface roughness (Ra) of the dry film after treatment. Each evaluation test method is described in detail below.

[0156] <Evaluation Test of Curability (Presence or Absence of Tack)> The curability was evaluated using the following method. Specifically, the dry films of Examples 1 to 13, manufactured using the method described above, were subjected to a 10 mW / cm² test using an electrodeless H-valve manufactured by Heraeus Corporation. ２ At an illuminance of 2000 mJ / cm² ２ The film was cured by irradiating it with ultraviolet light. After that, the surface of the cured film was touched with a finger. The curability was evaluated according to the following criteria. The results of the curability evaluation are summarized in Tables 3 and 4 below. Evaluation Criteria: Pass: No tack felt, or tack felt but no adhesion to the finger. Fail: Tack felt and a part of the film adhered to the finger (None)

[0157] <Evaluation Test of Glass Transition Temperature> Dry films of Examples 1 to 13, manufactured using the method described above, were cut to a size of 10 mm x 40 mm and attached to a dynamic viscoelasticity measuring device (Seiko Instruments Inc., "DMS6100"). Tests were conducted under conditions of strain amplitude of 10 μm, frequency of 10 Hz (sine wave), and heating rate of 5 °C / min, and the peak temperature of the calculated tanδ was adopted as the glass transition temperature (°C). The higher the glass transition temperature, the better the resin composition can be evaluated from the viewpoint of heat resistance. The measurement results of the glass transition temperature are summarized in Tables 3 and 4 below. If the glass transition temperature is 140 °C or higher, the resin composition is evaluated as having excellent heat resistance, and if the glass transition temperature is 135 °C or higher and less than 140 °C, the resin composition is evaluated as having standard heat resistance.

[0158] <Evaluation Test of Optical Loss at Wavelength 1310 nm> The optical loss at a wavelength of 1310 nm was measured by the following method. First, using the core dry film for each example and the common cladding dry film manufactured by the method described above, a 5 μm wide core was formed on the undercladding in the same manner as in the patternability evaluation test.

[0159] Subsequently, the cladding dry film was laminated onto the core formed at 80°C and 0.3 MPa using a vacuum laminator "V-130". After peeling off the release film from the laminated cladding dry film, it was heat-treated at 140°C for 20 minutes and then heated under a super-high pressure mercury lamp at 2 J / cm². ２ The dry cladding film was irradiated with ultraviolet light at a light intensity of [specify intensity]. Subsequently, the laminated film was further heat-treated at 160°C for 30 minutes to cure the dry cladding film and form an overcladding layer, thereby obtaining waveguide samples for evaluation of Examples 1 to 13.

[0160] Furthermore, for the measurement of optical loss at a wavelength of 1310 nm, waveguide samples for Examples 14 to 16 were prepared by using the same core dry film and developing it with a solution of different compositions. In Example 14, a waveguide sample was obtained in the same manner as in Example 1, except that a 5 μm wide core was formed on the underclad using a solution consisting of 100% cyclopentanone during development. In Example 15, a waveguide sample was obtained in the same manner as in Example 2, except that a 5 μm wide core was formed on the underclad using a solution consisting of 100% cyclopentanone during development. In Example 16, a waveguide sample was obtained in the same manner as in Example 2, except that a 5 μm wide core was formed on the underclad using a mixture of cyclopentanone and water with a mass ratio of 80:20 during development.

[0161] Next, the optical loss at a wavelength of 1310 nm was measured using the waveguide samples of each manufactured embodiment in the following manner. Light from a 1310 nm LED light source was passed through an optical fiber with a core diameter of 9 μm and an NA of 0.12, and incident on the end of the manufactured waveguide sample via matching oil (silicone oil). Furthermore, an optical fiber with a core diameter of 50 μm and an NA of 0.21 was passed through the same matching oil, and the opposite end of the waveguide sample was connected to a power meter to measure the power (P1) when an optical circuit was inserted. In addition, the power (P0) was measured by bringing the two similar optical fibers together without an optical circuit. From the measured values, the optical loss (dB / cm) at a wavelength of 1310 nm was calculated using the formula -10log(P1 / Po). The calculation results of the optical loss (dB / cm) at a wavelength of 1310 nm for each embodiment are summarized in Tables 3 and 4 below. If the optical loss was 0.60 dB / cm or less, it was evaluated as being well suppressed. If the optical loss was greater than 0.60 dB / cm but 0.80 dB / cm or less, it was evaluated as being suppressed to some extent.

[0162] <Arithmetic Mean Roughness (Ra) of the Surface of the Dry Film After Treatment> The arithmetic mean roughness (Ra) of the surface of the dry film after treatment was measured by the following method. Specifically, the dry films of Examples 1 to 13, manufactured by the method described above, were subjected to a high-pressure mercury lamp at 2000 mJ / cm². ２ After pattern exposure at a light intensity, the film was heat-treated at 150°C for 10 minutes. Subsequently, the film was immersed in a cyclopentanone:water mixture with a mass ratio of 96:4 at 25°C for 1 minute, and then dried at 120°C for 10 minutes. After drying, the arithmetic mean roughness (Ra) of the bottom surface of the obtained film, where the unexposed resin was removed by development, was measured using "HYBRID" manufactured by Lasertec Corporation. The smaller the arithmetic mean roughness (Ra) of the surface after such treatment, the less wall roughness there is after development, which is expected to lead to a reduction in light loss at a wavelength of 1310 nm. Therefore, if the arithmetic mean roughness (Ra) was greater than 0.4 μm, wall roughness was present, and the surface smoothness was evaluated as poor. On the other hand, if the arithmetic mean roughness (Ra) was 0.4 μm or less, wall roughness was minimal, and the surface smoothness was evaluated as good.

[0163] The reference evaluation test results for curability, glass transition temperature, light loss at a wavelength of 1310 nm, and arithmetic mean roughness (Ra) of the dry film after processing for each of the above examples are summarized in Tables 3 and 4 below, along with the core composition and the solution used during development. In the column for the solution used during development in Tables 3 and 4 below, "i" means a mixture of cyclopentanone and water with a mass ratio of 96:4, "ii" means a solution consisting of 100% cyclopentanone, and "iii" means a mixture of cyclopentanone and water with a mass ratio of 80:20. For Examples 14 to 16, evaluation tests other than the light loss at a wavelength of 1310 nm were not performed because the results were the same as those for Example 1 or Example 2.

[0164]

[0165]

[0166] <Discussion> As shown in Tables 3 and 4 above, the resin compositions of Examples 1 to 13 all met the acceptance criteria in terms of curability (presence or absence of tack).

[0167] Furthermore, particularly from a comparison of the glass transition temperatures between Example 9 and Example 10, it can be assumed that the lower the ratio of the second photocationic polymerization initiator (D) to the first photocationic polymerization initiator (C), the more the resin composition tends to have superior heat resistance.

[0168] On the other hand, a comparison of the light loss results between Examples 1 to 13 and Example 16 and Examples 14 and 15 revealed that light loss could be effectively suppressed by developing with a mixture containing an organic solvent (cyclopentanone) and water.

[0169] Furthermore, measurements of the arithmetic mean roughness (Ra) of the dry films after processing revealed that the dry films of Examples 1 to 13 exhibited minimal wall roughness and good surface smoothness after development. Therefore, it is expected that using these dry films will lead to a reduction in light loss at a wavelength of 1310 nm.

[0170] This application is based on Japanese Patent Application No. 2025-026162, filed on February 20, 2025, and its contents are included in this application.

[0171] The embodiments and examples disclosed herein should be understood in all respects to be illustrative and not restrictive. The scope of the present invention is indicated by the claims rather than by the foregoing description, and all modifications within the meaning and scope of the claims are intended to be included.

[0172] According to the present invention, it is possible to provide a resin composition for optical waveguides that enables high-precision patterning in the wavelength range of DI exposure. Therefore, by using this resin composition for optical waveguides to perform DI exposure and manufacture optical waveguides, it is possible to obtain optical waveguides with improved patterning accuracy and stable quality, and the yield can also be significantly improved.

Claims

1. The material comprises an epoxy compound (A), an anthracene-based photosensitizer (B), a first photocationic polymerization initiator (C), a second photocationic polymerization initiator (D), and one or more benzotriazole-based ultraviolet absorbers (E), wherein the first photocationic polymerization initiator (C) has a conjugate acid strength of HSbF ６ A polymerization initiator having a strength greater than or equal to HSbF, and having a first anion portion, wherein the second photocationic polymerization initiator (D) has a conjugate acid strength of HSbF ６ A resin composition for optical waveguides, comprising a polymerization initiator having a strength lower than that of a second anion portion.

2. The resin composition for optical waveguides according to claim 1, wherein the anthracene-based photosensitizer (B) comprises a compound represented by the structure of the following formula (1). (In formula (1), R １ Each of these is an alkyl group having 1 to 10 carbon atoms.

3. The first anion part is B(C ６ F ５ ), Ga(C ４ － ), SbF ６ F ５ ), and PF ４ － ; and the resin composition for an optical waveguide according to claim 1, comprising at least one selected from the group consisting of PF ６ － and P(C ３ F ２ F ５ ). ３ － ​ 4. The second anion unit is PF ６ － BF ４ － CF ３ SO ３ － ,CH ３ (C ６ H ４ ) SO ３ － , C ４ F ９ SO ３ － , R-SO ２ -N-SO ２ -R (R = alkyl skeleton), C(SO ２ -CF ３ ) ３ － The optical waveguide resin composition according to claim 1, comprising, and at least one selected from the group consisting of camphor sulfonic acid.

5. The optical waveguide resin composition according to claim 3, wherein the first photocationic polymerization initiator (C) comprises at least one polymerization initiator represented by the following formulas (2) to (5).

6. The optical waveguide resin composition according to claim 4, wherein the second photocationic polymerization initiator (D) comprises at least one polymerization initiator represented by the following formulas (6) to (8).

7. The resin composition for optical waveguides according to claim 1, wherein the benzotriazole compound (E) comprises a compound represented by the structure of the following formula (9).

8. The resin composition for optical waveguides according to claim 1, wherein the content of the anthracene-based photosensitizer (B) is 0.1 parts by mass or more and 3.0 parts by mass or less per 100 parts by mass of the epoxy compound (A).

9. The content of the first photocationic polymerization initiator (C) is 0.1 parts by mass or more and 6.0 parts by mass or less per 100 parts by mass of epoxy compound (A), the optical waveguide resin composition according to claim 1.

10. The content of the second photocationic polymerization initiator (D) is 0.1 parts by mass or more and 2.0 parts by mass or less per 100 parts by mass of epoxy compound (A), the resin composition for optical waveguides according to claim 1.

11. The resin composition for optical waveguides according to claim 1, wherein the content of the benzotriazole-based ultraviolet absorber (E) is 0.1 parts by mass or more and 2.0 parts by mass or less per 100 parts by mass of the epoxy compound (A).

12. The resin composition for optical waveguides according to claim 1, wherein the ratio of the content of anthracene-based photosensitizer (B) to the content of a first photocationic polymerization initiator (C) is 30% or more and 250% or less.

13. The optical waveguide resin composition according to claim 1, wherein the ratio of the content of the second photocationic polymerization initiator (D) to the content of the first photocationic polymerization initiator (C) is 10% or more and 150% or less.

14. The resin composition for optical waveguides according to claim 1, wherein epoxy compound (A) comprises a bisphenol A type epoxy compound.

15. The resin composition for optical waveguides according to claim 14, wherein epoxy compound (A) comprises two or more bisphenol A type epoxy compounds with different melting points.

16. A dry film having a layer containing an uncured or semi-cured optical waveguide resin composition according to any one of claims 1 to 15.

17. 2000 mJ / cm² with a high-pressure mercury lamp. ２ The dry film according to claim 16, wherein after pattern exposure at a light intensity, it is heated at 150°C for 10 minutes, immersed in a cyclopentanone:water mixture with a mass ratio of 96:4 at 25°C for 1 minute, and dried at 120°C for 10 minutes, the arithmetic mean roughness (Ra) of the unexposed pattern bottom surface is 0.4 μm or less.

18. A resin-coated film having a layer containing an uncured or semi-cured optical waveguide resin composition according to any one of claims 1 to 15, and a support film.

19. A liquid material comprising the optical waveguide resin composition according to any one of claims 1 to 15.

20. An optical waveguide comprising a core portion and a cladding portion having a lower refractive index than the core portion and formed to cover the core portion, wherein the core portion is formed using the optical waveguide resin composition described in any one of claims 1 to 15.

21. A method for manufacturing an optical waveguide according to claim 20, comprising developing using a mixed solution containing an organic solvent and water.

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