JP2012159591A - Resin composition for optical waveguide formation, dry film, and optical waveguide based on these - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a resin composition for optical waveguide formation which exhibits high heat resistance and refractive index controllability as well as low curing shrinkage, and also provide a dry film, and an optical waveguide base on these.SOLUTION: A resin composition for optical waveguide formation comprises a composition containing as essential components (A) a cyanate ester compound having two or more cyanate groups in a molecule, and/or a cyanate ester prepolymer, and (B) a fluorine atom-containing compound. A dry film, and an optical waveguide based on these are also provided.

Description

  The present invention relates to a resin composition for forming an optical waveguide excellent in heat resistance, light transmission characteristics, curing shrinkage, workability, and the like, a dry film, and an optical waveguide using these.

  In recent years, information terminals such as personal computers and mobile phones have rapidly demanded higher performance such as large-capacity data calculation, storage, and display, and along with this, technology for increasing the speed and density of devices has been rapidly developed. is doing. However, the conventional electric wiring technology has physical limitations on the wiring density such as signal delay and crosstalk in the printed wiring board, and it is expected that it is difficult to cope with further demands in the future. In order to solve these problems, optical interconnection technology is regarded as promising, and as an optical transmission medium for relatively short distances such as between substrates or in a substrate, wiring can be efficiently performed in a narrow space. Polymeric optical waveguides that can be easily connected and mounted at low cost are being actively studied.

The polymer-based optical waveguide is a system that includes a core surrounded by a clad, and that confines communication light in the core and transmits it. One of the most important points in polymer optical waveguide materials is the transmittance of the core material at the communication wavelength, and polymer waveguides having as low a propagation loss as possible are being developed. In optical interconnection between substrates, a surface-emitting type semiconductor laser that is compact and has excellent low power consumption is used as a light source for optical signals in order to convert the optical path to a right angle at the joint and take out the optical signal outside the substrate. It is done. The oscillation wavelength of the most widely used surface emitting laser is 0.85 μm (850 nm). As a guide for designing a waveguide material, the low optical propagation loss of the core material at this wavelength (practically about 0.5 dB / cm or less) is a problem.
Another important point for the optical waveguide material is the control of the refractive index. In order to confine and transmit communication light in the core, the average refractive index of the core needs to be higher than the average refractive index of the cladding. The difference in refractive index between the two is required to be 0.5% or more, and a material that can easily and accurately control the refractive index is desired. The polymer-based optical waveguide is not only used in the form of a flexible film, but is sometimes mounted in a rigid state on the surface of the substrate or inside the substrate, and may be used mixed with metal wiring. In the latter case, the polymer optical waveguide is required to have heat resistance that can withstand the lead-free solder reflow mounting process. As an optical waveguide material having both high transparency and high heat resistance, fluorinated polyimide (see, for example, Patent Document 1), epoxy resin / ethylenic double bond-containing resin (see, for example, Patent Document 2), epoxy resin / Acrylate resins (see, for example, Patent Document 3), radical polymerizable compounds / ethylenically unsaturated group-containing compounds (see, for example, Patent Document 4) have been developed.

  In the case of fluorinated polyimide, film formation requires heating conditions of 300 ° C. or more for several tens of minutes to several hours. However, because the heat resistance of existing electric wiring boards is insufficient, film formation on the electric wiring boards is not possible. It was difficult. Also, the adhesion with the substrate was not sufficient. Furthermore, since fluorinated polyimide is used to produce an optical waveguide using a method in which a liquid material is applied to a substrate to form a film, there are problems relating to the production of the optical waveguide, that is, processability, such as complicated film thickness management. It was.

On the other hand, Patent Documents 2 to 4 relate to the production of an optical waveguide using a dry film, and the above-described problem of workability related to the film thickness is improved, and both have excellent heat resistance and transparency. However, in the curing reaction using an acrylate group or an epoxy group, since the curing shrinkage is generally large, there is a problem that the adhesion to the substrate is lowered or the pattern forming accuracy is lowered.

As described above, in the production of an optical waveguide using a dry film that can accurately control the refractive index while achieving both high heat resistance and low propagation loss in the properties of the polymer optical waveguide, and excellent in optical waveguide moldability, None of the conventional materials satisfy the low curing shrinkage.

Japanese Patent Laid-Open No. 9-40774 JP 2006-71880 A JP 2007-84773 A JP 2008-33239 A

  In view of the above problems, an object of the present invention is to provide an optical waveguide clad resin composition having high heat resistance, refractive index controllability, and low cure shrinkage, a dry film, and an optical waveguide using the same. .

In view of the above problems, the present inventors have made extensive studies and found that the above problems can be solved by a composition containing a cyanate ester prepolymer and a fluorine atom-containing compound as essential components. It came to be completed.
That is, the present invention
1. (A) Cyanate ester prepolymer and / or cyanate ester compound having two or more cyanate groups in one molecule, (B) a resin composition for forming an optical waveguide comprising a composition containing a fluorine atom-containing compound as an essential component ,
2. (A) The resin composition for forming an optical waveguide as described in 1 above, wherein the cyanate ester prepolymer is a compound having at least two cyanate groups in the molecule;
3. (B) The resin composition for forming an optical waveguide according to any one of the above 1-2, wherein the fluorine atom-containing compound has a functional group that reacts with a cyanate group,
4). The resin composition for forming an optical waveguide according to any one of the above 1 to 3, wherein the component (A) is 40 to 99.5 parts by mass with respect to 100 parts by mass of the total amount of the composition,
5. A dry film for forming an optical waveguide, comprising the uncured resin composition layer comprising the resin composition for forming an optical waveguide according to any one of 1 to 4 above,
6). 5. An optical waveguide comprising a clad and a core, wherein the average refractive index of the core is higher than that of the clad, wherein the clad is a resin composition for forming an optical waveguide according to any one of 1 to 4 above or a dry for forming an optical waveguide according to 5 above. An optical waveguide formed of a cured product of a film, wherein the clad has a glass transition temperature of 150 ° C. to 250 ° C.,
Is to provide.

  If the resin composition for forming an optical waveguide or the dry film for forming a waveguide of the present invention is used, it becomes possible to provide an optical waveguide having excellent physical properties having high heat resistance and a practical level of light propagation loss. Furthermore, high-precision refractive index control and film thickness control are easy and significant curing shrinkage does not occur, so that an optical waveguide with high productivity and high accuracy can be provided in the optical waveguide manufacturing process.

Embodiments of the present invention will be described in detail below, but these are examples of the embodiments of the present invention and the present invention is not limited to these contents.

The resin composition for forming an optical waveguide of the present invention, a dry film, and an optical waveguide using these are: (A) a cyanate ester prepolymer and / or a cyanate ester compound having two or more cyanate groups in one molecule; (B) A composition comprising a fluorine atom-containing compound as an essential component.
The (A) cyanate ester prepolymer used here is not particularly limited, including known ones, but those having two or more cyanate groups in the molecule are preferred. For example, a resin obtained by polymerizing a cyanate ester compound having two or more cyanate groups in one molecule, a novolak-type cyanate ester resin represented by the following general formula (1), the following general formula (2) The dicyclopentadiene bisphenol-type cyanate ester resin etc. which are represented by these can be illustrated. These may be used alone or in combination of two or more.

Although it does not specifically limit as a cyanate ester compound which has a 2 or more cyanate group in said molecule | numerator including a well-known thing, For example, 1, 3- dicyanate benzene, 1, 4- dicyanate benzene, 2- tert-butyl-1,4-dicyanatebenzene, 2,4-dimethyl-1,3-dicyanatebenzene, 2,5-di-tert-butyl-1,4-dicyanatebenzene, tetramethyl-1,4 -Dicyanate benzene, 4-chloro-1,3- dicyanate benzene, 1,3,5-tricyanate benzene, 2,2'-dicyanate biphenyl, 4,4'-dicyanate biphenyl, 3,3 ', 5,5′-tetramethyl-4,4′-dicyanate biphenyl, 3,3 ′, 5,5′-tetrachloro-4,4′-dicyanate biphenyl 3,3 ′, 5,5′-tetrachloro-2,2′-dicyanate biphenyl, 1,3-dicyanate naphthalene, 1,4-dicyanate naphthalene, 1,5-dicyanate naphthalene, 1,6 -Dicyanate naphthalene, 1,8-dicyanate naphthalene, 2,6-dicyanate naphthalene, 2,7-dicyanate naphthalene, 1,3,6-tricyanate naphthalene, 4,4'-bis [(3-cyanate ) -Phenoxy] -diphenyl, 4,4′-bis [(4-cyanate) -phenoxy] -diphenyl, 2,2′-dicyanate-1,1′-binaphthyl, 4,4′-dicyanate diphenyl ether, 3, 3 ', 5,5'-tetramethyl-4,4'-dicyanate ether, 3,3', 5,5'-tetrachloro-4,4'-dicyanate Phenyl ether, 4,4′-bis (p-cyanatephenoxy) -diphenyl ether, 4,4′-bis (p-cyanatephenylisopropyl) -diphenyl ether, 4,4′-bis (p-cyanatephenoxy) -benzene, 4, , 4′-bis (m-cyanatephenoxy) -diphenyl ether, 4,4′-bis [4- (4-cyanatephenoxy) phenylsulfone] -diphenyl ether, 4,4′-dicyanate diphenylsulfone, 3,3 ′, 5,5′-tetramethyl-4,4′-dicyanate diphenylsulfone, 3,3 ′, 5,5′-tetrachloro-4,4′-dicyanate diphenylsulfone, 4,4′-bis (p- Cyanatephenylisopropyl) -diphenylsulfone, 4,4′-bis [(4-cyanate) -fur Noxy] -diphenylsulfone, 4,4′-bis [(3-cyanate) -phenoxy] -diphenylsulfone, 4,4′-bis [4- (4-cyanatephenylisopropyl) -phenoxy] -diphenylsulfone, 4, 4'-bis [4- (4-cyanatephenylsulfone) -phenoxy] -diphenylsulfone, 4,4'-bis [4- (4-cyanate) -diphenoxy] -diphenylsulfone, 4,4'-dicyanate diphenylmethane 4,4'-bis (p-cyanatephenyl) -diphenylmethane, 2,2'-bis (4-cyanatephenyl) -propane, 2,2'-bis (3,5-dimethyl-4-cyanatephenyl)- Propane, 2,2′-bis (3,5-dichloro-4-cyanatephenyl) -propane, 2,2′-bi (3,5-dibromo-4-cyanatephenyl) -propane, 1,1-bis (4-cyanatephenyl) -ethane, 1,1′-bis (p-cyanatephenyl) -cyclohexane, bis (2-cyanate-) 1-naphthyl) -methane, 1,2-bis (p-cyanatephenyl) -1,1,2,2-tetramethylethane, 4,4′-dicyanate benzophenone, 4,4′-bis (4-cyanate) ) -Phenoxybenzophenone, 1,4-bis (p-cyanatephenylphenylisopropyl) -benzene, diallylbisphenol A cyanate ester, 4,4′-methylenebis (2,6-dimethylphenylcyanate), 2,2′-bis ( p-cyanatephenyl) -hexafluoropropane, bis (4-cyanatephenyl) thioether Etc. These can be used alone or in combination of two or more. Among these, 2,2′-bis (4-cyanatephenyl) -propane, 1,1-bis (4-cyanatephenyl) -ethane, and bis (4-cyanatephenyl) thioether are particularly transparent and heat resistant. It is preferable. Furthermore, 2,2'-bis (4-cyanatephenyl) -propane is more preferable in terms of availability, transparency, heat resistance, and the like.

The method for obtaining a cyanate ester prepolymer by polymerizing a cyanate ester compound having two or more cyanate groups in one molecule is not particularly limited as long as a desired resin can be obtained. The polymerization reaction of a cyanate ester compound is a reaction in which a cyanate group is trimerized to form a triazine ring. Cyanate groups are known to react at temperatures above about 230 ° C., but catalysts can be added to facilitate this reaction. For example, protic acids represented by hydrochloric acid and phosphoric acid; Lewis acids represented by aluminum chloride and zinc chloride; aromatic hydroxy compounds represented by phenol, cumylphenol, pyrocatechol and dihydroxynaphthalene; zinc naphthenate and naphthene Organic metal salts such as cobalt oxide, tin octylate, cobalt octylate, zinc octylate, zinc 2-ethylhexanoate; organic typified by copper acetylacetonate, aluminum acetylacetonate, iron arene complex, ruthenium arene complex, etc. Metal complexes; tertiary amines such as triethylamine and tributylamine; quaternary ammonium salts represented by tetraethylammonium chloride and tetrabutylammonium bromide; imidazoles, sodium hydroxide, triphenylphosphine, and these Or the like can be mentioned a mixed system. Among these catalysts, preferred are organic metal salts such as zinc octylate and zinc 2-ethylhexanoate. Although these catalysts can be added in arbitrary ratios with respect to the cyanate ester compound, they are 0.005 to 20 parts by weight, preferably 0.01 to 5 parts by weight. The polymerization reaction temperature is 100 to 250 ° C, preferably 100 to 200 ° C.

  In the polymerization reaction, if necessary, a compound known to copolymerize with these can be added to modify the cyanate ester prepolymer. For example, an epoxy group-containing compound, a bismaleimide compound, a phenol group-containing compound, a carboxylic acid group-containing compound, an amide group-containing compound, and the like can be given. Although there is no limitation in these addition amounts, it is preferable that it is 50 mol% or less with respect to 100 mol% of cyanate ester compounds.

The polymerization reaction can be performed using only a cyanate ester compound, but it can also be performed in an organic solvent. The organic solvent to be used is not particularly limited as long as it can sufficiently dissolve the cyanate ester compound. For example, acetone, ruethyl ketone, methyl isobutyl ketone, methyl amyl ketone, tetrahydrofuran, dioxane, cyclopentanone, cyclohexanone, N, N- Examples include dimethylformamide, N, N-dimethylacetamide, N-methyl-2-pyrrolidone, γ-butyrolactone, ethylene glycol monoethyl ether, diethylene glycol monomethyl ether, diethylene glycol monobutyl ether, methyl glycol acetate, and chloroform. These can be used in combination of two or more.

  The cyanate ester prepolymer thus obtained is preferably a compound in which at least one triazine ring is formed. The upper limit of the number of triazine rings formed is not particularly limited because it depends on the characteristics of the cyanate ester compound used, but is preferably 6 or less, more preferably 4 or less. If the polymerization proceeds remarkably, it becomes insoluble in an organic solvent, which is not preferable.

The mass ratio of the component (A) to the total amount of 100 parts by mass in the resin composition of the present invention is preferably 40 to 99.5 parts by mass. If the mass ratio is less than 40 parts by mass, the heat resistance tends to decrease. It is not preferable. On the other hand, when the mass ratio is more than 0.5 parts by mass, the refractive index is not lowered sufficiently, which is not preferable as a clad resin composition. A more preferable mass ratio is 60 to 90 parts by mass, and even more preferably 70 to 80 parts by mass.

The fluorine atom-containing compound (B) in the present invention can be used without particular limitation including conventionally known compounds. Specific examples of such compounds include 2,2-bis (4-hydroxyphenyl) hexafluoropropane, 2,2-bis (4-aminophenyl) hexafluoropropane, and 2,2-bis (4-methylphenyl). ) Hexafluoropropane, 2,2-bis (3-amino-4-hydroxyphenyl) hexafluoropropane, 2,2-bis (3-aminophenyl) hexafluoropropane, hexafluoro-2,2-diphenylpropane, 2 , 2-bis (3-amino-4-methylphenyl) hexafluoropropane, 2,2-bis (3,4-dimethylphenyl) hexafluoropropane, octafluoro-4,4′-biphenol, 4,4′- Diaminooctafluorobiphenyl, 4-aminononafluorobiphenyl, perfluorobiphenyl, 4,4'-dimethoxyoctafluorobiphenyl 4,4′-dibromooctafluorobiphenyl, 4H, 4′H-octafluorobiphenyl, tetrafluorohydroquinone, pentafluorophenol, 2,3,5,6-tetrafluorophenol, tetrafluoro-1,4-benzoquinone, 2,3,5,6-tetrafluoro-1,4-phenylenediamine, 2,3,4-trifluorophenol, 2,3,5,6-tetrafluoroanisole, 3,4,5-trifluorophenol, Pentafluoroaniline, 2,4,5,6-tetrafluoro-1,3-phenylenediamine, hexafluorobenzene, 2,5-difluorophenol, 2,3-difluorophenol, pentafluorobenzenethiol, 2,2,3 , 4,4,4-hexafluoro-1-butanol, 2,2,3,3-tetrafluoro-1,4-butanediol, 2,2, 3,3,4,4,4-heptafluoro-1-butanol, 2,2,3,3,3-pentafluoro-1-propanol, 2,2,3,3-tetrafluoro-1-propanol, 2, -Fluorocyclohexanol, 2,2,3,3,4,4-hexafluoro-1,5-pentanediol, 1,2-epoxy-1H, 1H, 2H, 3H, 3H-trifluorobutane, 2,2 , 3,3-tetrafluoropropionic acid, 2,2,3,3,4,4,5,5-octafluoro-1-pentanol, 4,4,4-trifluorobutyric acid, 4,4,5, 5,5-pentafluoro-1-pentanol, 1H, 1H-nonafluoro-1-pentanol, 1,1,1,3,3,3-hexafluoro-2-propanol, 2,2,3,3, 4,4,5,5-octafluoro-1,6-hexanediol, 1H, 1H, 2H, 2H-nonafluoro-1-hexa 2,2,3,3,4,4,5,5-octafluoro-1-pentanol, 1H, 1H-nonafluoro-1-pentanol, 1H, 1H, 7H-dodecafluoro-1-heptanol 2,2,3,3,4,4,5,5,6,6,7,7-dodecafluoro-1,8-octanediol, 1H, 1H-tridecafluoro-1-heptanol, 2,2 , 3,3,4,4-hexafluoro-1,5-pentanediol, nonafluorovaleric acid, nonafluorovaleric acid, octafluoroadipic acid, 1H, 1H, 2H, 2H-tridecafluoro-1-n-octanol, 1H, 1H-pentadecafluoro-1-octanol, 1H, 1H, 9H-hexadecafluoro-1-nonanol, hexafluoroglutaric acid, and the like. These can be used alone or in combination of two or more. Among these, a compound having two or more phenolic hydroxyl groups or a hydroxyl group in the molecule reacts with the cyanate group in the (A) cyanate ester prepolymer and is preferable because the heat resistance is expected to be improved by improving the crosslinking density. . Further, 2,2-bis (4-hydroxyphenyl) hexafluoropropane (bisphenol AF) and octafluoro-4,4′-biphenol are preferably used in terms of availability, refractive index reduction efficiency, and reactivity. More preferred is 2,2-bis (4-hydroxyphenyl) hexafluoropropane in terms of refractive index.

The component (B) in the resin composition of the present invention can be used by modifying a cyanate ester prepolymer for a compound known to copolymerize with a cyanate ester.

In the present invention, a curing catalyst for cyanate ester and cyanate ester prepolymer may be added. The cyanate ester curing catalyst can be used without particular limitation as long as the cyanate group is trimerized and promotes the reaction to form a triazine ring. For example, protic acids represented by hydrochloric acid and phosphoric acid; Lewis acids represented by aluminum chloride and zinc chloride; aromatic hydroxy compounds represented by phenol, cumylphenol, pyrocatechol and dihydroxynaphthalene; zinc naphthenate and naphthene Organic metal salts such as cobalt oxide, tin octylate, cobalt octylate, zinc octylate, zinc 2-ethylhexanoate; organic typified by copper acetylacetonate, aluminum acetylacetonate, iron arene complex, ruthenium arene complex, etc. Metal complexes; tertiary amines such as triethylamine and tributylamine; quaternary ammonium salts represented by tetraethylammonium chloride and tetrabutylammonium bromide; imidazoles, sodium hydroxide, triphenylphosphine, and these Or the like can be mentioned a mixed system. Among these catalysts, preferred are organic metal salts such as zinc octylate and zinc 2-ethylhexanoate. In addition to the above, in the resin composition for forming an optical waveguide of the present invention, an antioxidant, an anti-yellowing agent, an ultraviolet absorber, a visible light absorber, a colorant, a plasticizer, and a stabilizer Additives such as inorganic fillers, internal mold release agents, and flame retardants may be added in proportions that do not adversely affect the effects of the present invention.

Next, the dry film of the present invention will be described in detail.
The dry film of the present invention has an uncured photosensitive resin composition layer containing the components (A) and (B). The resin composition layer is preferably not in a liquid state but in a dry state, for example. Preferably, a coating film made of the resin composition obtained by dissolving the resin composition for forming an optical waveguide containing the above (A) and (B) in an organic solvent to be liquefied, and coating and drying on a support film. Have. More preferably, a cover film for protecting the layer is laminated on the uncured photosensitive resin composition layer.

The material of the support film is not particularly limited, but is preferably transparent and has heat resistance, smoothness, solvent resistance, flexibility and toughness, polyesters such as polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polypropylene, Examples thereof include polyolefins such as polyethylene, polyamide, polyphenylene sulfite, polyether sulfite, polysulfone, polyether sulfone, polyarylate, polyimide, polyamideimide, polyetherimide, polyetheretherketone, and the like. Among these, polyethylene terephthalate is preferable from the viewpoint of excellent cost and physical property balance. The thickness of the base film is not particularly limited, but is preferably 5 to 100 μm. If the thickness is smaller than 5 μm, the mechanical strength as a support is insufficient, which is not preferable. If the thickness exceeds 100 μm, a gap with a mask at the time of pattern formation in exposure becomes large, and it becomes difficult to form a fine pattern. From the above viewpoint, the more preferable thickness of the base film is 10 to 50 μm.
Additives such as a lubricant, an antioxidant, a heat stabilizer, a viscosity modifier, a plasticizer, a dye improver, and a nucleating agent for improving slipperiness can be added to the base film. Further, both sides or one side of the base film to such an extent that the effects of the present invention are not adversely affected are provided with hydrophobicity, hydrophilicity, and antistatic properties by corona treatment, plasma treatment, ultraviolet irradiation, electron beam irradiation, chemical treatment, etc. A surface modification treatment such as imparting releasability may be performed.

The material of the cover film is not particularly limited, but preferably has good peelability and surface smoothness from the flexible and uncured photosensitive resin composition layer. Polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate Examples thereof include polyesters such as phthalate, polyolefins such as polypropylene and polyethylene, and polyamides. Among these, polyolefin is preferable in that it is excellent in cost and physical property balance. The thickness of the cover film is not particularly limited, but is preferably 1 to 50 μm. If it is smaller than 1 μm, the mechanical strength as a support is insufficient, which is not preferable, and if it exceeds 50 μm, flexibility is insufficient, which is not preferable. Additives such as a lubricant, an antioxidant, a heat stabilizer, a viscosity modifier, a plasticizer, a dye improver, and a nucleating agent for improving slipperiness can be added to the cover film. Further, both sides or one side of the base film to such an extent that the effects of the present invention are not adversely affected are provided with hydrophobicity, hydrophilicity, and antistatic properties by corona treatment, plasma treatment, ultraviolet irradiation, electron beam irradiation, chemical treatment, etc. A surface modification treatment such as imparting releasability may be performed.

The dry film of the present invention is a resin solution in which the uncured photosensitive resin composition containing the components (A) and (B) is dissolved in an organic solvent, which is applied to a base film, and the solvent is heated. It can be manufactured by evaporating and removing.
The organic solvent used here is not particularly limited as long as it can dissolve the resin composition. For example, acetone, methyl ethyl ketone, methyl isobutyl ketone, methyl amyl ketone, tetrahydrofuran, dioxane, cyclopentanone, cyclohexanone, Examples thereof include N, N-dimethylformamide, N, N-dimethylacetamide, N-methyl-2-pyrrolidone, γ-butyrolactone, ethylene glycol monoethyl ether, diethylene glycol monomethyl ether, diethylene glycol monobutyl ether, and methyl glycol acetate. These can be used in combination of two or more. The resin concentration in the resin solution is preferably 20 to 80 parts by mass.

The method for forming the photosensitive resin composition layer on the support film is not particularly limited, but spin coating, dipping, spraying, bar coating, roll coating, curtain coating, gravure printing, Examples thereof include a method in which a solvent is scattered using a dryer or the like after coating on a base film using a method such as a silk screen method or an ink jet method. The film thickness to be applied may be appropriately selected according to the design structure of the optical waveguide to be manufactured and the resin solution concentration, but it is usually preferably in the range of 1 μm to 1000 μm. Drying may be performed under normal pressure or reduced pressure, and the temperature condition for scattering the organic solvent is 50 to 150 ° C.
The content of the organic solvent remaining after drying is preferably 20 parts by mass or less, and more preferably 10 parts by mass or less. If it exceeds 20 parts by mass, there are problems such as adversely affecting the storage stability of the dry film and deteriorating the accuracy of pattern formation by exposure.
The film thickness of the photosensitive resin composition layer after drying is usually 1 to 250 μm.
The dry film thus obtained can be easily stored and stored, for example, by winding it into a roll.

Next, a method for forming an optical waveguide using a dry film made of the resin composition for forming an optical waveguide of the present invention will be described.
The optical waveguide of the present invention is composed of an upper clad / core / lower clad, and the dry film made of the resin composition for forming an optical waveguide of the present invention is a material for forming these cores and / or clads. The refractive index of the core needs to be higher than the refractive index of the cladding, and the relative refractive index difference is at least 0.5% or more, more preferably 1.0% or more. In the resin composition for forming an optical waveguide of the present invention, the refractive index can be arbitrarily controlled by changing the amount of each composition according to the refractive index of each of the components (A) and (B). And tends to depend on the respective refractive index and blending ratio. In particular, by changing the amount of component (B), the refractive index can be controlled without greatly changing the properties of the resin. The upper cladding composition is preferably the same as the lower cladding composition.

First, a method for producing a lower clad using a dry film made of the resin composition for forming an optical waveguide of the present invention will be described in detail.
When the cover film is laminated on the dry film, the cover film is peeled off, and then the resin composition layer surface (cladding composition) is brought into close contact with the substrate, followed by pressure bonding (laminating) while heating. Can do. In order to improve the adhesion to the substrate and the shape followability, it is also possible to heat laminate under reduced pressure. The laminating temperature of the dry film is preferably 50 to 150 ° C., and the pressure bonding pressure is preferably 0.1 to 1.0 MPa, but these conditions are not particularly limited.
Next, after the support film is peeled off, a heat treatment is performed to cure the cyanate ester prepolymer as the component (A). However, the heat treatment may be performed simultaneously with the formation of the core and the upper clad. The heat treatment condition may be a heat treatment temperature of 50 to 250 ° C., more preferably 180 ° C. to 230 ° C., and a heat treatment time of 5 minutes to 5 hours, more preferably 30 minutes to 1 hour. Heat treatment may be performed.

Next, a method for producing an upper clad using a dry film made of the resin composition for forming an optical waveguide of the present invention will be described.
After the core is formed by an arbitrary method, an upper clad is formed on the core. The same laminating method and irradiation with active energy rays can be performed as in the production of the lower clad. After peeling off the support film, heat treatment is performed to cure the cyanate ester prepolymer as component (A). The heat treatment conditions are usually 50 to 250 ° C. for 5 minutes to 5 hours, and the heat treatment may be performed by gradually increasing the heating temperature. This heat treatment can also be performed as a heat treatment of the component (A) of the lower cladding layer and / or the core layer.

The cladding layer can be formed by any method other than the method using the dry film. For example, methods such as a bar coating method, a spin coating method, a spray coating method, an ink jet method, and a dipping method are used using a dope obtained by dissolving the waveguide forming resin composition of the present invention in an organic solvent. The thickness of the core layer is preferably 20 to 60 μm, and the thickness of the cladding layer (underclad, overclad on the core) is preferably 10 to 200 μm.

The glass transition temperature of the clad in the optical waveguide of the present invention is preferably 150 to 250 ° C. More preferably, it is 180-250 degreeC. If the glass transition temperature is lower than 150 ° C., light propagation may be reduced due to deformation of the core or cladding, or distortion at the core / cladding interface at the lead-free solder reflow process temperature. It is unpreferable. When the glass transition temperature is higher than 250 ° C., there is no problem in physical properties, but it is not preferable because the thermosetting temperature needs to be increased. In general, the glass transition temperature of a thermosetting resin tends to strongly depend on the curing treatment temperature, and when a high glass transition temperature is to be obtained, a thermosetting treatment at a higher temperature tends to be required. In such a case, not only the productivity is lowered but also the physical properties of the substrate material on which the optical waveguide is mounted may be adversely affected.

When the clad in the optical waveguide of the present invention is formed from a dry film for forming an optical waveguide, their curing shrinkage rate is preferably 0% to 5%. The curing shrinkage rate in the present invention includes a shrinkage rate that is cured by irradiation with active energy rays and a shrinkage rate that is cured by a subsequent heat treatment. The shrinkage rate can be measured using the density method, and the specific gravity of the resin composition for forming a waveguide constituting the dry film, the specific gravity after curing with active energy rays, and the specific gravity after curing by heat treatment are measured. Can be calculated. From the viewpoint of adhesion to an adjacent substrate or resin layer, the curing shrinkage is preferably 0% to 5%. However, if it is less than 0% or greater than 5%, the adjacent substrate or resin layer is Is unfavorable because distortion tends to occur between and the adhesiveness tends to decrease.

An embedded optical waveguide can be produced from the dry film for optical waveguides or the resin composition of the present invention. An embedded optical waveguide is a structure in which a core material is formed in a thin film on a clad substrate, a waveguide portion is formed by various methods, and the same clad layer as the substrate is provided thereon.

EXAMPLES Hereinafter, although an Example demonstrates this invention concretely, it is not limited to these Examples.
<Preparation and Evaluation-1 of Optical Waveguide Forming Resin Composition and Optical Waveguide Forming Dry Film (for Core)> (Examples 1 to 6, Comparative Example 1)
[Synthesis Example of Cyanate Ester Prepolymer (A-1)]
In a flask equipped with a refluxing vessel, 20.0 g of 2,2-bis (4-cyanatephenyl) propane, 0.076 g of p-cumylphenol and 8.5 g of tetrahydrofuran were added, and 2-ethylhexanoic acid was used as a reaction catalyst. 20 ppm of zinc was added and reacted at 150 ° C. for 5 hours with stirring. Tetrahydrofuran was distilled off by an evaporator to obtain a white cyanate ester prepolymer (A-1). The reduction rate of the cyanate group peak (2237 cm ⁻¹ ) was determined using FT-IR (FT / IR-6100, JASCO), and the reaction rate was calculated to be 70%.
[Synthesis Example of Cyanate Ester Prepolymer (A-2)]
In a flask equipped with a reflux condenser, 7.7 g of 2,2-bis (4-cyanatephenyl) propane, 2.3 g of bisphenol AF, and 4.4 g of tetrahydrofuran were added, and 20 ppm of zinc 2-ethylhexanoate was used as a reaction catalyst. The mixture was added and reacted at 100 ° C. for 40 minutes with stirring. Tetrahydrofuran was distilled off by an evaporator to obtain a brown cyanate ester prepolymer (A-2). The reaction rate obtained in the same manner as described above was 80%.
[Synthesis Example of Cyanate Ester Prepolymer (A-3)]
In a flask equipped with a reflux condenser, 4.5 g of 2,2-bis (4-cyanatephenyl) propane, 5.5 g of bisphenol AF, and 4.4 g of tetrahydrofuran were added, and 20 ppm of zinc 2-ethylhexanoate was used as a reaction catalyst. The mixture was added and reacted at 100 ° C. for 5 minutes with stirring. Tetrahydrofuran was distilled off by an evaporator to obtain a brown cyanate ester prepolymer (A-3). The reaction rate obtained in the same manner as described above was 95%.
Component (A): cyanate ester prepolymer and component (B): fluorine atom-containing compound shown in Table 1 were dissolved in γ-butyrolactone to obtain a resin varnish for producing a dry film for forming an optical waveguide.
This was applied to a polyethylene terephthalate film (thickness 25 μm) using an applicator, dried at normal pressure (10 minutes at 80 ° C.), and then dried under reduced pressure (30 minutes at 80 ° C.). At this time, the space | interval of the applicator was adjusted so that the thickness of the resin composition layer of the dry film after drying might be set to 30 micrometers.
The characteristics in the following examples were evaluated by the following methods.
[Laminating properties]
The optical waveguide forming dry film was transferred to the substrate by a hot roll pressure bonding method (100 ° C.). At this time, the case where the film could be uniformly transferred to the substrate was indicated by “◯”, and the case where the film could not be transferred to the substrate or the thickness of the uncured photosensitive resin composition layer was uneven was indicated by “X”. In addition, the board | substrate used here was obtained by adding 2-ethyl hexanoic acid zinc (Zn density | concentration; 200 ppm) to 1, 1-bis (4-cyanate phenyl) ethane, and thermosetting at 180 degreeC for 1 hour. A cured product plate having a thickness of 1 mm was obtained.
[Glass transition temperature: Tg]
Using a differential scanning calorimeter (DSC-50) manufactured by Shimadzu Corporation, the glass transition temperature was determined from a heat flow curve at a sample weight of 4 mg, a temperature measurement range of 30 ° C. to 300 ° C., and a heating rate of 10 ° C./min.
[Refractive index; n]
Using a Metricon prism coupler (model 2010), a laser beam having a wavelength of 850 nm was incident on the sample through the coupling prism, and the refractive indexes of TE polarized light and TM polarized light were measured. The average refractive index was calculated as [2 × (refractive index with TE polarization) + (refractive index with TM polarization)] / 3.

※Ａ−２、Ａ−３はＢ成分であるフッ素原子含有化合物を含むシアネートエステルプレポリマーである。

* A-2 and A-3 are cyanate ester prepolymers containing a fluorine atom-containing compound which is a B component.

As a result of the above evaluations, an optical waveguide forming dry film (for clad) having excellent laminating properties was obtained. Moreover, the refractive index could be arbitrarily controlled by adding the component (B).

<Fabrication of embedded optical waveguide>
(Example 7)
A clad varnish composed of cyanate ester prepolymer (A-2) / γ-butyrolactone = 100/70 (mass ratio) was applied to a polyethylene terephthalate film (thickness 25 μm) using an applicator, and dried at normal pressure (at 80 ° C. 10 minutes) and then dried under reduced pressure (80 ° C. for 30 minutes). At this time, the space | interval of the applicator was adjusted so that the thickness of the resin composition layer of the dry film after drying might be set to 30 micrometers. The obtained dry film for clad was laminated on an FR4 (glass / epoxy) substrate by a hot roll pressure bonding method (100 ° C.), and then stepwise heat treatment in a nitrogen atmosphere (120 ° C. for 20 minutes, 150 ° C. 30 minutes, 60 minutes at 180 ° C.), the cyanate ester prepolymer was cured to produce a clad.
Next, a varnish for core consisting of cyanate ester prepolymer (A-1) / 9,9-bis [4- (2-acryloyloxyethoxy) phenyl] fluorene / DAROCUR1173 = 50/50/3 is formed on the cladding layer. After laminating the core dry film produced in the same manner as described above, a photomask (core width 40 μm) was placed on the polyethylene terephthalate film as the support film and vacuum-adhered, and a UV exposure machine was used with a wavelength of 360 nm and an illuminance of 10 mW / cm 2. Were irradiated for 360 seconds. The support film was peeled off, developed by immersion for 120 seconds in a γ-butyrolactone solvent, and then washed with methyl ethyl ketone to obtain a core pattern.
The clad varnish is spin-coated on this core layer, dried at atmospheric pressure (80 ° C. for 10 minutes), then dried under reduced pressure (80 ° C. for 30 minutes), and then stepwise heat-treated in a nitrogen atmosphere ( 20 minutes at 120 ° C., 30 minutes at 150 ° C., and 60 minutes at 180 ° C.) to produce an upper clad cured film. Furthermore, the whole structure was heat-treated at 230 ° C. for 60 minutes in a nitrogen atmosphere to react unreacted cyanate groups in the cladding and the core. At this time, no significant curing shrinkage was observed in both the core and the clad. When a cross section of the obtained structure was observed with a digital microscope, a rectangular core cross section (upper and lower sides 30 μm, height 40 μm) was formed, and it was confirmed that an embedded optical waveguide was fabricated. The relative refractive index difference between the core and the clad was 0.9%.

If the resin composition for forming an optical waveguide or the dry film for forming a waveguide of the present invention is used, it becomes possible to provide a highly heat-resistant optical waveguide material for cladding. Furthermore, it is easy to control the refractive index and film thickness with high accuracy, and since there is no significant curing shrinkage when forming the core pattern, to provide an optical waveguide with high productivity and high core pattern formation accuracy in the optical waveguide manufacturing process. Can do.
The optical waveguide of the present invention is suitable for optical devices such as optical transmission bodies, optical multiplexers, optical demultiplexers, optical modulators, optical switches, touch panel applications, and the like.

Claims (6)

An optical waveguide comprising: (A) a cyanate ester prepolymer and / or a cyanate ester compound having two or more cyanate groups in one molecule; and (B) a composition containing a fluorine atom-containing compound as an essential component. Resin composition. 2. The resin composition for forming an optical waveguide according to claim 1, wherein the (A) cyanate ester prepolymer is a compound having at least two cyanate groups in the molecule. (B) The resin composition for forming an optical waveguide according to claim 1, wherein the fluorine atom-containing compound has a functional group that reacts with a cyanate group. The resin composition for forming an optical waveguide according to any one of claims 1 to 3, wherein the component (A) is 40 to 99.5 parts by mass with respect to 100 parts by mass of the total amount of the composition. 5. A dry film for forming an optical waveguide, comprising an uncured resin composition layer comprising the resin composition for forming an optical waveguide according to claim 1. The optical waveguide forming resin composition according to any one of claims 1 to 4 or the optical waveguide formation according to claim 5, wherein the clad and the core comprise an optical waveguide having a higher average refractive index of the core than the cladding. An optical waveguide characterized by being formed from a cured product of a dry film for use, wherein the clad has a glass transition temperature of 150 ° C to 250 ° C.