TW201839049A - Photosensitive epoxy resin composition for forming optical waveguide core, photosensitive film for forming optical waveguide core, optical waveguide, opto-electric hybrid board, and method for manufacturing optical waveguide - Google Patents

Abstract

Provided is a photosensitive epoxy resin composition for forming an optical waveguide core comprising a resin component and a photocationic polymerization initiator, the resin component comprising an epoxy cresol novolac resin having three or more epoxy groups, a solid bisphenol-type epoxy resin having two epoxy groups, a liquid bisphenol-type epoxy resin having two epoxy groups, and a solid fluorene ring-containing epoxy compound.

Description

Photosensitive epoxy resin composition for forming an optical waveguide core, photosensitive film for forming an optical waveguide core, optical waveguide, opto-electric hybrid substrate, and optical waveguide manufacturing method

The present invention relates to a photosensitive epoxy resin composition for forming an optical waveguide core, a photosensitive thin film for forming an optical waveguide core, an optical waveguide, an opto-electric hybrid substrate, and a method for producing an optical waveguide.

BACKGROUND OF THE INVENTION Optical waveguides for transmitting optical signals have been known for the past. The optical waveguide has a core layer through which the optical signal passes and a cladding layer covering the core layer.

In order to ensure the performance of the optical waveguide, the core layer must be balanced to have various characteristics. For example, the core layer must have low absorption loss (linear loss) and high refractive index for suppressing optical loss, good flexibility for ensuring flexibility of the optical waveguide, good pattern properties by photolithography, and the like.

The material of the core layer has been proposed in the literature as a photosensitive epoxy resin composition for forming an optical waveguide, which contains an epoxy resin and a photocationic polymerization initiator, and the epoxy resin is composed only of a solid epoxy resin component (for example, a reference patent) Document 1).

Further, the photosensitive epoxy resin composition for forming an optical waveguide is formed into a core layer by a wet process. Specifically, the photosensitive epoxy resin composition for forming an optical waveguide is dissolved in an organic solvent to prepare a photosensitive varnish, and the photosensitive varnish is applied onto the under cladding layer and dried, and then the dried dry film is dried. Exposure and development are performed to form a core layer.

Prior Art Document Patent Document Patent Document 1: International Publication No. 2016/203999

Disclosure of the Invention Problems to be Solved by the Invention However, as shown in Fig. 6A, when a core layer is formed by a wet process, a photosensitive varnish is applied onto the under clad layer 31, so that the coated surface 33A is in a uniform state. Therefore, once the recess 32 is formed in the lower cladding layer 31 in the manufacturing step, the thickness T1 of the coating film 33 corresponding to the recess 32 of the lower cladding layer 31 is higher than the thickness T2 of the portion without the recess 32 (with the lower cladding layer 31). The thickness of the coating film 33 corresponding to the flat surface is thicker.

As a result, the thickness of the dry film 34 formed by drying the coating film 33 of the photosensitive varnish cannot be kept constant as a whole, and the dimensional accuracy of the core layer formed by the exposure and development of the dry film 34 is lowered.

Further, a dry process in which a photosensitive varnish is applied to a carrier film and dried to prepare a dry film having a constant thickness is attached, and the dry film is attached to the under cladding layer.

In this dry process, as shown in Fig. 6B, even if the under clad layer 31 has the recess 32, the dry film 34 is attached in conformity with the recess 32 of the under clad layer 31, so that the thickness of the dry film 34 can be maintained as a whole. Constant, so that the core layer dimensional accuracy can be improved.

On the other hand, in the dry process, after the dry film 34 is attached to the under clad layer 31, the carrier film 35 is peeled off from the dry film 34, so that the dry film 34 needs to have adhesion to the under clad layer 31 and The peelability of the carrier film 35.

However, the dry film prepared by the photosensitive epoxy resin composition for forming an optical waveguide described in Patent Document 1 cannot ensure the adhesion required for the dry process, and cannot be stably adhered to the under cladding layer.

Accordingly, the present invention provides a photosensitive epoxy resin composition for forming an optical waveguide core which can be suitably used for ensuring various characteristics required for an optical waveguide and which can be applied to a core layer formed by a dry process, and an optical waveguide core. A method for producing a photosensitive film, an optical waveguide, an opto-electric hybrid substrate, and an optical waveguide for forming.

Means for Solving the Problem The present invention [1] includes a photosensitive epoxy resin composition for forming an optical waveguide core, which contains a resin component and a photocationic polymerization initiator, and the resin component contains a group having three or more epoxy groups. A phenol novolak type epoxy resin, a solid bisphenol type epoxy resin having two epoxy groups, a liquid bisphenol type epoxy resin having two epoxy groups, and a solid oxime-containing epoxy compound.

The photosensitive epoxy resin composition for forming an optical waveguide core according to the above [1], wherein the cresol novolac type epoxy resin, the solid bisphenol type epoxy resin, and the liquid state are contained. 100 parts by mass of the total of the bisphenol type epoxy resin and the solid fluorene-containing epoxy compound, and the content ratio of the cresol novolac type epoxy resin is 45 parts by mass or more and 60 parts by mass or less, and the solid bisphenol type epoxy The content ratio of the resin is 15 parts by mass or more and 25 parts by mass or less, and the content ratio of the liquid bisphenol type epoxy resin is 15 parts by mass or more and 25 parts by mass or less, and the content ratio of the solid fluorene-containing epoxy compound is 5 More than the mass part and 15 parts by mass or less.

The present invention [3] includes a photosensitive film for forming an optical waveguide core, comprising a resin composition layer containing the photosensitive epoxy for forming an optical waveguide core according to [1] or [2] above. Resin composition.

The invention [4] includes an optical waveguide comprising a core layer containing the cured product of the photosensitive epoxy resin composition for forming an optical waveguide core according to the above [1] or [2].

The optical waveguide according to the above [4], further comprising a cladding layer having a core layer and having a refractive index of 1.554 or less.

The invention [6] includes an opto-electric hybrid substrate comprising the optical waveguide described in the above [4] or [5].

The present invention [7] includes a method of producing an optical waveguide, the method comprising the steps of: forming a lower cladding layer; and the resin composition layer of the photosensitive thin film for forming an optical waveguide core according to the above [3] Attached to the under cladding layer; exposing and developing the resin composition layer to form a core layer on the under cladding layer; and forming an over cladding layer on the under cladding layer so as to cover the core layer.

According to the photosensitive epoxy resin composition for forming an optical waveguide core of the present invention, the resin component contains a cresol novolac type epoxy resin which is a crosslinkable component, a solid bisphenol type epoxy resin which is a softening component, and A liquid bisphenol type epoxy resin and a solid cerium-containing epoxy compound which is a refractive index adjusting component.

Therefore, the core layer containing the cured product of the photosensitive epoxy resin composition for forming an optical waveguide core can ensure low absorption loss, excellent pattern properties, excellent flexibility, and high refractive index in a well-balanced manner.

In addition, since the flexibility imparting component contains the liquid bisphenol epoxy resin, the resin composition layer adhesive layer containing the photosensitive epoxy resin composition for forming an optical waveguide core can be provided.

Therefore, the photosensitive epoxy resin composition for forming an optical waveguide core can ensure various characteristics required for the optical waveguide in a well-balanced manner, and can be suitably applied to form a core layer by a dry process.

Since the photosensitive film for forming an optical waveguide core of the present invention includes the resin composition layer containing the photosensitive epoxy resin composition for forming an optical waveguide core, it is possible to ensure various characteristics required for the optical waveguide in a well-balanced manner, and is suitable for It is applied to form a core layer by a dry process.

Since the optical waveguide of the present invention includes the core layer containing the cured product of the photosensitive epoxy resin composition for forming an optical waveguide core, the various characteristics required for the optical waveguide can be ensured in a well-balanced manner, and the core layer dimensional accuracy can be improved. .

Since the opto-electric hybrid board of the present invention includes the above-described optical waveguide, various characteristics required for the optical waveguide can be ensured in a well-balanced manner, and the dimensional accuracy of the core layer can be improved.

According to the method of producing an optical waveguide of the present invention, the resin composition layer of the optical waveguide core forming photosensitive film is attached to the under cladding layer, and then the resin composition layer is exposed and developed to be packaged. A core layer is formed on the layer. That is, the core layer can be formed using a dry process.

Therefore, it is possible to smoothly manufacture an optical waveguide which has a desired balance of various characteristics and has a core layer having good dimensional accuracy.

In the form of the photosensitive epoxy resin composition for forming an optical waveguide core of the present invention, the photosensitive epoxy resin composition for forming an optical waveguide core of the present invention (hereinafter referred to as a core epoxy resin composition) will be described below. The epoxy resin composition for a core is a material of a core layer of an optical waveguide, and contains a resin component and a photocationic polymerization initiator. 1. Resin component The resin component contains a cresol novolac type epoxy resin, a solid bisphenol type epoxy resin, a liquid bisphenol type epoxy resin, and a solid fluorene-containing epoxy compound, and it is preferable to constitute only these.

In addition, hereinafter, "solid state" means a solid state which exhibits no fluidity at normal temperature (25 ° C ± 5 ° C), and "liquid state" means a liquid state which has fluidity at normal temperature (25 ° C ± 5 ° C). (1-1) Cresol novolac type epoxy resin The cresol novolac type epoxy resin is a crosslinkable component and has three or more epoxy groups. The cresol novolac type epoxy resin is in a solid state having no fluidity at normal temperature (25 ° C ± 5 ° C), as shown by the following formula (1). General formula (1)

[Chemical Formula 1]

[In the formula (1), n represents an integer of 1 or more and 4 or less. The cresol novolac type epoxy resin represented by the above formula (1) has a main chain comprising a cresol novolac structure (constituted) and a side chain containing a glycidyl ether unit.

When the resin component contains a cresol novolac type epoxy resin, it is possible to surely reduce the absorption loss of the core layer described later, and it is possible to surely reduce the optical loss.

Commercially available materials can also be used for the cresol novolac type epoxy resin. Commercially available cresol novolac type epoxy resins are YDCN-704A (epoxy equivalent: 204 to 216 g/eq.), YDCN-700-10 (epoxy equivalent: 198 to 210 g/eq.), YDCN-700- 7 (epoxy equivalent: 196 to 210 g/eq.), YDCN-700-3 (epoxy equivalent: 194 to 208 g/eq.) (all manufactured by Nippon Steel & Sumitomo Chemical Co., Ltd.). These cresol novolac type epoxy resins may be used singly or in combination of two or more.

The cresol novolac relative to the total of the cresol novolak type epoxy resin, the solid bisphenol type epoxy resin, the liquid bisphenol type epoxy resin and the solid fluorene-containing epoxy compound (hereinafter referred to as total epoxy component), 100 parts by mass The content of the epoxy resin is, for example, 30 parts by mass or more and preferably 45 parts by mass or more, more preferably 50 parts by mass or more, and is, for example, 70 parts by mass or less and preferably 60 parts by mass or less.

When the content ratio of the cresol novolac type epoxy resin is at least the above lower limit, it is possible to reduce the absorption loss of the core layer described later and to improve the pattern property. When the content ratio of the cresol novolac type epoxy resin is less than or equal to the above upper limit, the content of the other epoxy component can be ensured, and various characteristics required for the optical waveguide can be ensured in a well-balanced manner. (1-2) Solid bisphenol type epoxy resin Both the solid bisphenol type epoxy resin and the liquid bisphenol type epoxy resin are softness imparting components which impart flexibility to the core layer described later.

The solid bisphenol type epoxy resin has two epoxy groups. For example, a solid bisphenol type epoxy resin has a molecular chain containing a plurality of aromatic rings and an epoxy group bonded to both ends of the molecular chain.

The epoxy equivalent weight in the solid bisphenol type epoxy resin is, for example, 450 g/eq. or more and preferably 500 g/eq. or more, and is, for example, 5000 g/eq. or less and preferably 800 g/eq. or less.

Such a solid bisphenol type epoxy resin can be exemplified by a solid bisphenol A type epoxy resin.

If the solid bisphenol type epoxy resin contains a solid bisphenol A type epoxy resin, the softness of the core layer can be surely improved. Further, the solid bisphenol type epoxy resin is preferably composed of a solid bisphenol A type epoxy resin.

The solid bisphenol A type epoxy resin is a copolymer of bisphenol A and epichlorohydrin, and has a glycidyl ether unit at both ends of the molecular chain.

A commercially available product can also be used as the solid bisphenol A type epoxy resin. Commercially available products of solid bisphenol A type epoxy resin may be JER1002 (epoxy equivalent: 600 to 700 g/eq.), JER1003 (epoxy equivalent: 670 to 770 g/eq.), and JER1004 (epoxy equivalent: 875 to 975 g/ Eq.), JER1007 (epoxy equivalent: 1750 to 2200 g/eq.), JER1010 (epoxy equivalent: 3000 to 5000 g/eq.) (all manufactured by Mitsubishi Chemical Corporation), and the like. The solid bisphenol A type epoxy resins of this type may be used singly or in combination of two or more.

Further, the resin component may contain a solid bisphenol A type epoxy resin in addition to a solid bisphenol A type epoxy resin, and may also contain other bisphenol type epoxy resins such as a solid bisphenol F type epoxy resin.

When the resin component contains solid bisphenol A epoxy resin and other bisphenol epoxy resin, solid bisphenol A epoxy resin is the main component in solid bisphenol epoxy resin, and other bisphenol epoxy in solid state The resin (bisphenol F type epoxy resin, etc.) is an accessory component. The solid bisphenol A type epoxy resin is, for example, 90% by mass or more and 100% by mass or less based on the total amount of the solid bisphenol type epoxy resin (the sum of the bisphenol A type epoxy resin and the other bisphenol type epoxy resin) The other bisphenol type epoxy resin (solid bisphenol F type epoxy resin) in a solid state is, for example, 0% by mass or more and 10% by mass or less based on the total amount of the solid bisphenol type epoxy resin.

The content ratio of the solid bisphenol-type epoxy resin is, for example, 10 parts by mass or more and preferably 15 parts by mass or more, more preferably 20 parts by mass or more, and is, for example, 30 parts by mass or less, based on 100 parts by mass of the total epoxy component. It is preferably 25 parts by mass or less, more preferably 22 parts by mass or less.

When the content ratio of the solid bisphenol type epoxy resin is at least the above lower limit, it is possible to surely improve the flexibility of the core layer to be described later. When the content ratio of the solid bisphenol-type epoxy resin is at most the above upper limit, the content of the other epoxy component can be ensured, and various characteristics required for the optical waveguide can be surely ensured in a well-balanced manner. (1-3) Liquid bisphenol type epoxy resin The liquid bisphenol type epoxy resin is a softness imparting component and is also an adhesive imparting component which imparts adhesiveness to the core resin composition layer described later.

The liquid bisphenol type epoxy resin has two epoxy groups. For example, a liquid bisphenol type epoxy resin has a molecular chain containing a plurality of aromatic rings and an epoxy group bonded to both ends of the molecular chain.

The epoxy equivalent weight in the liquid bisphenol type epoxy resin is, for example, 170 g/eq. or more and preferably 180 g/eq. or more, and is, for example, 300 g/eq. or less and preferably 200 g/eq. or less.

Liquid bisphenol type epoxy resins of this type may be exemplified by liquid bisphenol A type epoxy resins.

When the liquid bisphenol type epoxy resin contains a liquid bisphenol A type epoxy resin, the softness of the core layer described later can be surely improved. Further, the liquid bisphenol type epoxy resin is preferably composed of a liquid bisphenol A type epoxy resin.

The liquid bisphenol A type epoxy resin has the same structure as the solid bisphenol A type epoxy resin except for the repeating amount.

A commercially available product can also be used as the liquid bisphenol A type epoxy resin. Commercially available materials of liquid bisphenol A type epoxy resin are JER828 (epoxy equivalent: 184 to 194 g/eq.), JER825 (epoxy equivalent: 170 to 180 g/eq.), and JER827 (epoxy equivalent: 180 to 190 g/ Eq.), JER828EL (epoxy equivalent: 184 to 194 g/eq.), JER828US (epoxy equivalent: 184 to 194 g/eq.), JER828XA (epoxy equivalent: 197 to 215 g/eq.) (all manufactured by Mitsubishi Chemical Corporation, etc.) The liquid bisphenol A type epoxy resin of this type may be used alone or in combination of two or more.

Further, the resin component may contain a liquid bisphenol type epoxy resin in addition to a liquid bisphenol A type epoxy resin, and may contain another bisphenol type epoxy resin such as a liquid bisphenol F type epoxy resin.

When the resin component contains liquid bisphenol A epoxy resin and other bisphenol epoxy resin, liquid bisphenol A epoxy resin is the main component in liquid bisphenol epoxy resin, and other bisphenol epoxy in liquid state The resin (bisphenol F type epoxy resin, etc.) is an accessory component. The liquid bisphenol A type epoxy resin is, for example, 90% by mass or more and 100% by mass or less based on the total amount of the liquid bisphenol type epoxy resin (the sum of the bisphenol A type epoxy resin and the other bisphenol type epoxy resin). The liquid bisphenol type epoxy resin (bisphenol F type epoxy resin) is, for example, 0% by mass or more and 10% by mass or less based on the total amount of the liquid bisphenol type epoxy resin.

The content ratio of the liquid bisphenol-type epoxy resin is, for example, 5 parts by mass or more, and preferably 10 parts by mass or more, more preferably 15 parts by mass or more, and for example, 30 parts by mass or less, based on 100 parts by mass of the total epoxy component. It is preferably 25 parts by mass or less, more preferably 20 parts by mass or less.

In addition, the content of the liquid bisphenol type epoxy resin is, for example, 5 parts by mass or more, and preferably 7 parts by mass or more, more preferably 15 parts by mass or more, and is, for example, about 100 parts by mass of the cresol novolak type epoxy resin. It is preferably 100 parts by mass or less and preferably 80 parts by mass or less, more preferably 60 parts by mass or less.

In addition, the content of the liquid bisphenol type epoxy resin is, for example, 10 parts by mass or more, and preferably 25 parts by mass or more, more preferably 50 parts by mass or more, and is, for example, 100 parts by mass of the solid bisphenol type epoxy resin. It is 300 parts by mass or less and preferably 200 parts by mass or less, more preferably 150 parts by mass or less.

In addition, the content of the liquid bisphenol-type epoxy resin is, for example, 20 parts by mass or more, and preferably 50 parts by mass or more, more preferably 100 parts by mass or more, based on 100 parts by mass of the solid fluorene-containing epoxy compound, and is, for example, It is preferably 800 parts by mass or less and preferably 700 parts by mass or less, more preferably 400 parts by mass or less.

When the content ratio of the liquid bisphenol type epoxy resin is at least the above lower limit, the adhesion of the core resin composition layer to be described later can be improved, and the core resin composition layer to be described later can be surely adhered to the under cladding layer or the cover film. With. When the content ratio of the liquid bisphenol type epoxy resin is less than or equal to the above upper limit, the adhesion of the core resin composition layer to be described later is excessively increased, and the cover film and the carrier film can be smoothly peeled off from the core resin composition layer. In other words, when the content ratio of the liquid bisphenol type epoxy resin is within the above range, the adhesion of the coating film resin composition layer described later can be surely adjusted within the range of the dry process. (1-4) Solid oxime-containing epoxy compound The solid yttrium-containing epoxy compound is a refractive index adjusting component for adjusting the refractive index of the core layer of the optical waveguide. The solid oxime-containing epoxy compound has an anthracene ring and an epoxy group.

The solid fluorene-containing epoxy compound of this type may be an anthracene-containing epoxy compound represented by the following chemical formula (2). Chemical formula (2)

[Chemical Formula 2]

The anthracene ring-containing epoxy compound represented by the above chemical formula (2) is a crystalline monomer.

When the solid fluorene-containing epoxy compound contains the fluorene-containing epoxy compound represented by the above chemical formula (2), the refractive index of the core layer described later can be surely improved. Further, the solid oxime-containing epoxy compound is preferably composed of an oxime-containing epoxy compound represented by the above chemical formula (2).

A commercially available product may be used as the oxime-containing epoxy compound represented by the above formula (2), and may be, for example, OGSOL PG-100 (manufactured by Osaka Gas Chemicals Co., Ltd.).

The content of the solid fluorene-containing epoxy compound is, for example, 1 part by mass or more, and preferably 5 parts by mass or more, more preferably 8 parts by mass or more, and for example, 25 parts by mass or less, based on 100 parts by mass of the total epoxy component. It is preferably 15 parts by mass or less, more preferably 10 parts by mass or less.

When the content ratio of the solid fluorene-containing epoxy compound is at least the above lower limit, the refractive index of the core layer can be improved. When the content ratio of the solid fluorene-containing epoxy compound is less than or equal to the above upper limit, the content of the other epoxy component can be ensured, and the various characteristics required for the optical waveguide can be ensured in a well-balanced manner. (1-5) Other Resin Component Further, the resin component may contain the above specific epoxy component (cresol novolac type epoxy resin, solid bisphenol type epoxy resin, liquid bisphenol) within a range not inhibiting the effects of the present invention. A resin component other than the epoxy resin and the solid oxime-containing epoxy compound).

The other resin component may, for example, be another epoxy component (for example, a liquid-containing anthracene-containing epoxy compound), a polyolefin-based resin, a polyoxymethylene-based resin, or an urethane-based resin. These other resin components may be used alone or in combination of two or more.

In addition, the content ratio of the specific epoxy component (total epoxy component) is, for example, 90% by mass or more and 100% by mass or less in the resin component. In addition, the content ratio of the other resin component is, for example, 0% by mass or more and 10% by mass or less in the resin component. 2. Photocationic polymerization initiator The photocationic polymerization initiator is a photoacid generator which generates an acid by light irradiation, and the core epoxy resin composition is cured by light irradiation (for example, ultraviolet irradiation).

The photocationic polymerization initiator may, for example, be a hexafluoroantimony sulfonium salt (such as triphenylsulfonium hexafluoroantimonate, p-phenylthiophenyl)phenyldiphenylphosphonium hexafluoroantimonate or 4-chlorophenyl hydride. Phenylphosphonium hexafluoroantimonate, bis[4-(diphenyldihydrothio)phenyl]sulfide bishexafluoroantimonate, diphenylphosphonium hexafluoroantimonate, etc.), hexafluorophosphate Barium salts (such as triphenylsulfonium hexafluorophosphate, p-(phenylthio)phenyldiphenylphosphonium hexafluorophosphate, 4-chlorophenyldiphenylphosphonium hexafluorophosphate, double [4-(two) Phenyldihydrothio)phenyl]sulfide bishexafluorophosphate, (2,4-cyclopentadien-1-yl)[(1-methylethyl)benzene]-Fe-hexafluorophosphate and many more. The photocationic polymerization initiator may be used singly or in combination of two or more.

Among the photocationic polymerization initiators, a hexafluoroantimony sulfonium salt is preferred, and more preferred are triphenylsulfonium hexafluoroantimonate and diphenylphosphonium hexafluoroantimonate.

The content ratio of the photo-cationic polymerization initiator is, for example, 0.1 part by mass or more, and preferably 0.25 part by mass or more, and is, for example, 3 parts by mass or less and preferably 1 part by mass or less based on 100 parts by mass of the resin component. 3. Other additives, etc. The core epoxy resin composition may contain an organic solvent and an antioxidant as needed.

When the core epoxy resin composition contains an organic solvent, the core epoxy resin composition can be prepared into a core-forming varnish (hereinafter referred to as core varnish).

The organic solvent may, for example, be an ester (such as ethyl lactate or propylene glycol methyl acetate), a ketone (such as methyl ethyl ketone, cyclohexanone, 2-butanone, etc.) or an ether (such as digans). Methyl ether, diethylene glycol methyl ethyl ether, propylene glycol monomethyl ether, tetramethylfuran, dimethoxyethane, etc.), guanamines (such as N, N-dimethylacetamide, etc.), An ester is desirable, and an ethyl lactate is more preferable. The organic solvents may be used singly or in combination of two or more.

The content ratio of the organic solvent is, for example, 20 parts by mass or more, and preferably 40 parts by mass or more, and is, for example, 80 parts by mass or less and preferably 60 parts by mass or less based on 100 parts by mass of the resin component.

When the epoxy resin composition for a core contains an antioxidant, oxidative degradation of the epoxy resin composition for the core can be prevented, and the stability of the epoxy resin composition for the core can be improved.

The antioxidant may, for example, be a hindered phenol-based antioxidant or a phosphate-based antioxidant. The antioxidants may be used singly or in combination of two or more. Among the antioxidants, a hindered phenol-based antioxidant and a phosphate-based antioxidant are preferably used in combination.

The content ratio of the antioxidant is, for example, 0.1 part by mass or more, and preferably 0.5 part by mass or more, and is, for example, 3 parts by mass or less and preferably 1 part by mass or less based on 100 parts by mass of the resin component.

Further, the core epoxy resin composition may contain a decane-based or titanium-based coupling agent, a adhesion-imparting agent, a leveling agent, an antifoaming agent, and the like in an appropriate ratio as needed.

In the epoxy resin composition for a core, the resin component contains a cresol novolac type epoxy resin which is a crosslinkable component (reactive component), a solid bisphenol type epoxy resin which is a softening component, and a liquid bisphenol. A type epoxy resin and a solid cerium-containing epoxy compound which is a refractive index adjusting component.

Therefore, the core layer containing the cured product of the epoxy resin composition for the core can ensure low absorption loss, excellent pattern property, excellent flexibility, and high refractive index in a well-balanced manner.

Further, since the flexibility imparting component contains the liquid bisphenol-type epoxy resin, the core resin composition layer adhesiveness of the core-containing epoxy resin composition can be imparted.

Therefore, the core epoxy resin composition can ensure various characteristics required for the optical waveguide in a well-balanced manner, and can be suitably applied to form a core layer by a dry process.

Further, in the epoxy resin composition for a core, the content ratio of the cresol novolac type epoxy resin, the solid bisphenol type epoxy resin, the liquid bisphenol type epoxy resin, and the solid fluorene-containing epoxy compound is preferably The above range.

In particular, in the epoxy resin composition for a core, first, in order to ensure pattern and dry process suitability (dry film suitability), the respective ratios of the cresol novolac type epoxy resin and the liquid bisphenol type epoxy resin are set to the above. Within the scope.

Then, under the premise of ensuring the respective contents of the cresol novolac type epoxy resin and the liquid bisphenol type epoxy resin, the solid bisphenol is balanced in such a manner that the softness and refractive index of the core layer can be balanced. The respective proportions of the epoxy resin and the solid fluorene-containing epoxy compound are designed to be within the above range.

Therefore, the core layer of the cured product of the epoxy resin composition for the core can ensure excellent pattern property and dry process suitability, and at the same time, excellent flexibility and high refractive index can be ensured in a well-balanced manner. <Photosensitive film for forming an optical waveguide core> Next, a core photosensitive film 1 according to an embodiment of the photosensitive film for forming an optical waveguide core of the present invention will be described with reference to FIG.

As shown in FIG. 1, the core photosensitive film 1 is provided with the core resin composition layer 2 (an example of a resin composition layer), the carrier film 3, and the cover film 4 of the core-containing epoxy resin composition. Further, the core photosensitive film 1 is a member for fabricating a member (core layer) of an optical waveguide, and specifically comprises a core resin composition layer 2, a carrier film 3, and a cover film 4, and is capable of being circulated as a member alone. And devices that can be utilized in the industry.

The core resin composition layer 2 is a dried product of the above-mentioned core epoxy resin composition, and is a dry film having a film shape (plate shape). Specifically, the core resin composition layer 2 has a predetermined thickness and is elongated in a predetermined direction orthogonal to the thickness direction and has a flat surface and a flat back surface.

In the core resin composition layer 2, the above epoxy component (cresol novolac type epoxy resin, solid bisphenol type epoxy resin, liquid bisphenol type epoxy resin, solid fluorene-containing epoxy compound) is not polymerized, and the core The resin composition layer 2 contains these epoxy components in an uncured state. The core resin composition layer 2 has surface adhesion.

The carrier film 3 is detachably attached to the back surface of the core resin composition layer 2 to support and protect the core resin composition layer 2 before the core photosensitive film 1 is used to form the core layer. In other words, when the core photosensitive film 1 is shipped, transported, and stored, the carrier film 3 is laminated on the back surface of the core resin composition layer 2 so as to cover the back surface of the core resin composition layer 2, and can be used for the core. The photosensitive film 1 is a flexible film which is currently peeled off from the back surface of the core resin composition layer 2 in a substantially U-shaped manner.

The carrier film 3 has a flat plate shape, specifically has a predetermined thickness, and is elongated in a predetermined direction orthogonal to the thickness direction and has a flat surface and a flat back surface. The adhering surface (surface) of the carrier film 3 has been subjected to a peeling treatment in accordance with the demand. The carrier film 3 is preferably light transmissive.

The material of the carrier film 3 may be a resin material such as polyester (such as polyethylene terephthalate (PET)) or polyolefin (such as polyethylene or polypropylene).

The cover film 4 is detachably attached to the surface of the core resin composition layer 2 before the core photosensitive film 1 is used to form the core layer, thereby protecting the core resin composition layer 2. In other words, the cover film 4 is laminated on the surface of the core resin composition layer 2 so as to cover the surface of the core resin composition layer 2 when the core photosensitive film 1 is shipped, transported, and stored, and can be used for the core. The photosensitive film 1 is a flexible film which is currently peeled off from the surface of the core resin composition layer 2 in a slightly U-shaped manner.

The cover film 4 has a flat plate shape, specifically has a predetermined thickness, is elongated in a predetermined direction orthogonal to the aforementioned thickness direction, and has a flat surface and a flat back surface. Further, the covering surface (back surface) of the cover film 4 has been subjected to a peeling treatment in accordance with the demand. The material of the cover film 4 may be the same resin material as that of the carrier film 3. <Method for Producing Photosensitive Film for Optical Waveguide Core Formation> Next, a method for producing the photosensitive film 1 for core will be described.

To produce the photosensitive film 1 for a core, for example, a core epoxy resin composition (preferably a core varnish) can be applied to the surface of the carrier film 3 by a known method.

Next, the core epoxy resin composition was dried by heating to form a coating film.

Thereby, the core resin composition layer 2 formed of the core epoxy resin composition can be prepared by drying the coating film.

Next, the cover film 4 is attached to the surface of the core resin composition layer 2 by a known bonding machine.

The photosensitive film 1 for cores was manufactured above. <Opto-electric hybrid substrate> The core photosensitive film 1 has the core resin composition layer 2 for the core-containing epoxy resin composition, so that various characteristics required for the optical waveguide can be ensured in a well-balanced manner, and the application can be suitably applied. The dry process is used to form the core layer.

In the present embodiment, a case where the core photosensitive film 1 is used to manufacture the opto-electric hybrid board 7 including the optical waveguide 8 will be described with reference to Figs. 2 to 5F.

First, the configuration of the opto-electric hybrid board 7 will be described with reference to Figs. 2 to 4 . In FIG. 2, in order to clarify the relative arrangement and shape of the core layer 10 to be described later, the over cladding layer 12 which will be described later is omitted.

As shown in FIGS. 2 to 4, the opto-electric hybrid board 7 has a substantially flat plate shape elongated in a predetermined direction. The opto-electric hybrid board 7 includes an integrally formed electric circuit board 9 and an optical waveguide 8. The electric circuit board 9 and the optical waveguide 8 are laminated in the thickness direction of the opto-electric hybrid board 7.

As shown in FIG. 3, the electric circuit board 9 is provided with the metal supporting layer 15, the insulating base layer 16, the conductor layer 17, and the cover insulating layer 18, and it is preferable to comprise only it.

The metal supporting layer 15 is a reinforcing layer that strengthens the conductor layer 17. The metal supporting layer 15 is set at one end in a predetermined direction in the electric circuit board 9. The material of the metal supporting layer 15 may be a metal such as stainless steel. The metal supporting layer 15 has a plurality of (three) opening portions 19 corresponding to a plurality of (three) core portions 13 to be described later. The opening 19 penetrates the metal supporting layer 15 in the thickness direction.

The insulating base layer 16 is an insulating layer that insulates the conductor layer 17 and the metal supporting layer 15 between the conductor layer 17 and the metal supporting layer 15 in the thickness direction of the electric circuit board 9. The base insulating layer 16 is elongated to cover the entire electrical circuit substrate 9. The material of the base insulating layer 16 may be a resin such as polyimide.

The conductor layer 17 is a signal layer that transmits an electrical (electrical signal) between an external circuit board (not shown) and an optical element (not shown). The conductor layer 17 is provided at one end of the electric circuit board 9 in a predetermined direction. The material of the conductor layer 17 may be a conductor such as copper.

The conductor layer 17 has a pattern shape having a first terminal 20, a second terminal 22, and a wiring 21 that electrically connects the first terminal 20 and the second terminal 22. Two (one pair) first terminals 20 are provided in each of the plurality of core portions 13 to be described later. The second terminal 22 is provided in plurality so as to correspond to the plurality of first terminals 20, and is electrically connected to each of the first terminals 20 by the wires 21.

The insulating layer 18 is covered with the wiring 21 and disposed on the insulating base layer 16 so that the first terminal 20 and the second terminal 22 are exposed. The material covering the insulating layer 18 may be a resin such as polyimide.

The optical waveguide 8 is a strip-loaded type optical waveguide. The optical waveguide 8 is disposed on the electric circuit board 9 and has flexibility. The optical waveguide 8 has a cladding layer 11 and an upper cladding layer 12 and a core layer 10 as an example of a cladding layer, and it is preferable to constitute only the same. The lower cladding layer 11 and the upper cladding layer 12 cover the core layer 10.

The lower cladding layer 11 is laminated on the electric circuit substrate 9. The material of the under cladding layer 11 is, for example, a resin having transparency and flexibility, and will be described later in detail.

The refractive index of the lower cladding layer 11 is, for example, 1.560 or less and preferably 1.554 or less.

The core layer 10 is disposed on the lower cladding layer 11. The core layer 10 contains a cured product of the above-mentioned epoxy resin composition, and is preferably composed of a cured product of the above-mentioned core epoxy resin composition. The core layer 10 has flexibility.

As shown in FIGS. 2 and 4, the core layer 10 has a plurality of (three) core portions 13 arranged to be spaced apart from each other in the width direction of the optical waveguide 8. The core portion 13 has a slightly rectangular shape in plan view elongated in a predetermined direction.

As shown in FIG. 3, the core 13 has a mirror surface 14. The mirror surface 14 is formed by cutting the opening, and is a slope which forms an angle of 45 degrees with respect to the direction in which the core 13 is elongated. When the mirror surface 14 is projected in the thickness direction, it is positioned in the opening portion 19 of the metal supporting layer 15.

The refractive index of the core layer 10 is greater than the refractive indices of the lower cladding layer 11 and the upper cladding layer 12. Specifically, the refractive index of the core layer 10 is, for example, 1.583 or more and preferably 1.084 or more.

As shown in FIG. 4, the upper clad layer 12 is disposed on the under clad layer 11 so as to cover the core layer 10. The material of the upper cladding layer 12 is, for example, a resin having transparency and flexibility, and is preferably the same as the material of the lower cladding layer 11.

The refractive index of the upper cladding layer 12 is smaller than the refractive index of the core layer 10. The refractive index range of the upper cladding layer 12 is the same as the refractive index range of the lower cladding layer 11. <Manufacturing Method of Photoelectric Mixed Substrate> Next, a method of manufacturing the opto-electric hybrid board 7 as an embodiment of the optical waveguide manufacturing method of the present invention will be described with reference to FIGS. 5A to 5F.

The manufacturing method of the opto-electric hybrid board 7 includes the following steps: a step of preparing the electric circuit substrate 9; a lower-pack forming step to form the under clad layer 11 (FIG. 5A); and an attaching step of the core-using photosensitive film 1 The core resin composition layer 2 is attached to the under clad layer 11 (Fig. 5B); in the core forming step, the core resin composition layer 2 is exposed and developed to form the core layer 10 on the under clad layer 11 (Fig. 5C~ FIG. 5E); and an over-pack forming step of forming the over clad layer 12 on the under clad layer 11 in a manner of covering the core layer 10 (FIG. 5D). The manufacturing method of such an opto-electric hybrid board 7 is preferably carried out by a roll-to-roll method.

First, the electric circuit board 9 is prepared as shown in FIGS. 2 to 4, and the electric circuit board 9 includes a metal supporting layer 15, an insulating base layer 16, a conductor layer 17, and a cover insulating layer 18.

Next, as shown in FIG. 5A, a resin composition layer for cladding layer formed of a material of the under cladding layer 11 is formed on the electric circuit substrate 9 in the lower package forming step, and then the under cladding layer 11 is formed by photolithography.

Further, it is preferable that the reinforcing sheet 26 is attached to the back surface of the electric circuit board 9 (the surface opposite to the surface on which the under cladding layer 11 is formed) before the under-pack forming step to reinforce the electric circuit board 9. The reinforcing sheet 26 is a substrate material of the electric circuit board 9, and may be a resin film such as a PET film.

The method for forming the clad resin composition layer is not particularly limited, and may be a wet process in which a clad varnish containing a material of the under clad layer 11 is applied onto the electric circuit substrate 9 and dried, or may be a dry process. In other words, the clad varnish is applied to the carrier film and dried to prepare a resin composition layer for cladding, and then the clad resin composition layer is attached to the electric circuit substrate 9.

The clad varnish contains, for example, an epoxy resin component for a cladding layer and the photocationic polymerization initiator, and the organic solvent and the antioxidant described above may be contained in an appropriate ratio as needed.

The epoxy resin component for the cladding layer is not particularly limited, and examples thereof include a polyfunctional epoxy resin and a difunctional epoxy resin.

The polyfunctional epoxy resin has three or more epoxy groups, and may be exemplified above as a cresol novolac type epoxy resin or a solid alicyclic polyfunctional epoxy resin (for example, 2,2-bis(hydroxymethyl)-1). a 1,2-epoxy-4-(2-oxiranyl)cyclohexane adduct of butanol, etc., 1,3,5-paraxeoxypropyl tripolyisocyanate or the like. The polyfunctional epoxy resins may be used singly or in combination of two or more.

The difunctional epoxy resin has two epoxy groups, and the solid bisphenol epoxy resin, the liquid bisphenol epoxy resin, the liquid difunctional epoxy resin represented by the following formula (3), A solid difunctional epoxy resin represented by the formula (4) or the like. The difunctional epoxy resins may be used singly or in combination of two or more.

General formula (3)

[Chemical Formula 3]

[In the formula (3), R ¹ represents a hydrogen atom or a methyl group. The plurality of R ¹ may be the same or different from each other. R ² represents one selected from the group consisting of a hydrogen atom, a methyl group, a chlorine atom and a bromine atom. The plurality of R ² may be the same or different from each other. X represents an alkylene group or an alkyleneoxy group having 2 to 15 carbon atoms. A plurality of Xs may be identical to each other or different from each other. n is 1 or more and 5 or less. ] General formula (4)

[Chemical Formula 4]

[In the formula (4), R ¹ represents one atom selected from the group consisting of a hydrogen atom, a methyl group, a chlorine atom and a bromine atom. The plurality of R ¹ may be the same or different from each other. X represents an alkylene group or an alkylene group having 2 to 15 carbon atoms. A plurality of Xs may be identical to each other or different from each other. n is 1 or more and 1000 or less. Next, in the attaching step, first, as shown by the imaginary line in FIG. 1, the cover film 4 is peeled off from the core photosensitive film 1.

Next, as shown in FIG. 5B, the core resin composition layer 2 is placed so as to face the under cladding layer 11, and the core resin composition layer 2 is attached to the under cladding layer 11 by a known bonding machine.

In this case, the bonding temperature is, for example, 40 ° C or higher and preferably 60 ° C or higher, and is, for example, 120 ° C or lower and preferably 100 ° C or lower. The adhesion pressure is, for example, 0.05 MPa or more and preferably 0.1 MPa or more, and is, for example, 1.0 MPa or less and preferably 0.5 MPa or less.

Next, in the core forming step, first, as shown in FIG. 5C, the core resin composition layer 2 is irradiated with ultraviolet rays over the carrier film 3 via the photomask 25 on which the slit corresponding to the pattern of the core layer 10 is formed.

At this time, the ultraviolet ray transmits the carrier film 3, and the portion of the core resin composition layer 2 corresponding to the core layer 10 is exposed. Thereby, the core resin composition is cured to form a core layer 10 formed of a cured product of the core resin composition.

The irradiation amount of the ultraviolet rays is, for example, 10 mJ/cm ² or more and preferably 100 mJ/cm ² or more, more preferably 500 mJ/cm ² or more, and is, for example, 20,000 mJ/cm ² or less and preferably 15,000 mJ/cm ² or less, more preferably 10,000 mJ. /cm ² or less.

Next, as shown in FIG. 5D, the carrier film 3 is peeled off from the core resin composition layer 2 after exposure. The exposed core is then preferably prebaked with the resin composition layer 2.

The heating temperature is, for example, 80 ° C or higher and preferably 100 ° C or higher, and is, for example, 250 ° C or lower and preferably 150 ° C or lower. The heating time is, for example, 10 seconds or longer and preferably 5 minutes or longer, and is, for example, 2 hours or shorter and preferably 1 hour or shorter.

Next, as shown in FIG. 5E, development processing is performed by a known developing solution (for example, γ-butyrolactone or the like) to dissolve and remove the unexposed portion in the core resin composition layer 2.

Thereby, the core layer 10 is formed on the under clad layer 11.

Next, in the upper package forming step, the resin composition layer for cladding layer formed of the material of the upper cladding layer 12 is formed on the under cladding layer 11 so as to cover the core layer 10, and then the over cladding layer 12 is formed by photolithography.

The method for forming the clad resin composition layer may be the same as the above method in forming the under clad layer 11, and the material of the over clad layer 12 may be the same as the material of the under clad layer 11.

Next, after the reinforcing sheet 26 is peeled off from the electric circuit board 9, the optical waveguide 8 is subjected to outer shape processing to form a mirror surface 14 (refer to FIG. 2).

The photovoltaic hybrid substrate 7 can be manufactured in the above manner.

As shown in FIGS. 3 and 4, the opto-electric hybrid board 7 includes the core layer 10 containing the cured product of the core epoxy resin composition. Therefore, the various characteristics required for the optical waveguide 8 can be ensured in a well-balanced manner, and the core layer can be obtained. 10 dimensional accuracy improvement.

Further, as shown in FIG. 5A, in the method of manufacturing the opto-electric hybrid board 7, it is preferable to attach the reinforcing sheet 26 to the electric circuit board 9 before the step of forming the under-pack. At this time, the electric circuit board 9 is deformed (deflected) by the pressure applied to the reinforcing sheet 26, and when it is transported in a roll-to-roll, the tension is caused by the tension on the electric circuit board 9. Further, the electric circuit board 9 includes an insulating base layer 16 and a cover insulating layer 18 made of a resin, and a metal supporting layer 15 and a conductor layer 17 made of a metal. Therefore, the electrical circuit substrate 9 may be recessed due to the difference in rigidity or coefficient of linear expansion of members made of different materials.

Moreover, once the under clad layer 11 is formed on the electric circuit substrate 9 having the recess, the under clad layer 11 follows the recess of the electric circuit substrate 9 and also forms a recess in the under clad layer 11 (cf. Fig. 6B).

In the method of manufacturing the above-described opto-electric hybrid board 7, the core resin composition layer 2 of the core photosensitive film 1 is attached to the under clad layer 11 as shown in FIG. 5B to FIG. The core layer 10 is formed on the under clad layer 11 by exposure and development of the resin composition layer 2. That is, the core layer 10 is formed by a dry process.

Therefore, even if the under cladding layer 11 has a recess, it is possible to smoothly manufacture the opto-electric hybrid board 7 having the core layer 10 having the various characteristics as desired and having excellent dimensional accuracy. <Modification>

In the modification, members and steps that are the same as those in the above-described embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted.

As shown in Fig. 1, the core photosensitive film 1 is provided with a core resin composition layer 2, a carrier film 3, and a cover film 4. However, the photosensitive film for forming an optical waveguide core of the present invention is not limited thereto. The photosensitive film for forming an optical waveguide core may have no carrier film 3 and/or cover film 4 as long as it has the core resin composition layer 2 . In other words, the photosensitive film for forming an optical waveguide core may be composed only of the core resin composition layer 2, or may be provided with any of the core resin composition layer 2, the carrier film 3, and the cover film 4.

In the above embodiment, the opto-electric hybrid board 7 including the optical waveguide 8 and the electric circuit board 9 has been described, but is not limited thereto. The optical waveguide 8 can also be provided on the substrate instead of the electrical circuit substrate 9. The substrate may be, for example, a tantalum wafer, a metal substrate (such as a stainless steel plate), a glass substrate, or the like.

In the above-described embodiment, the positive portion in which the exposed portion of the core resin composition layer 2 is insolubilized and the unexposed portion of the core resin composition layer 2 is solubilized in the core forming step is described, but is not limited thereto, and may be The unexposed portion of the core resin composition layer 2 is insolubilized and the unexposed portion of the core resin composition layer 2 is insoluble in a negative form.

The same effects as those of the first embodiment can be exerted for each of the above modifications. The above embodiments and modifications can be combined as appropriate. Example

The present invention will be further specifically described below by way of examples and comparative examples. In addition, the invention is not limited by these. Further, the specific values of the blending ratio (content ratio), the physical property value, and the parameters used in the following descriptions may be substituted for the blending ratios (content ratios) corresponding to those described in the above "Forms for Carrying Out the Invention". ), physical property values, parameters, etc., the upper limit of the description (defined as "below", "less than") or lower limit (defined as "above", "exceeded"). In addition, the "parts" and the symbol "%" are submitted as quality benchmarks unless otherwise stated. Production Example 1 (Modulation cladding varnish)

Solid, alicyclic polyfunctional epoxy resin (2,2-bis(hydroxymethyl)-1-butanol 1,2-epoxy-4-(2-oxirane) under light-shielding conditions 30% of a solid bisphenol type epoxy resin (trade name: YX-7180BH40, manufactured by Mitsubishi Chemical Corporation) of the above formula (4), 30 parts of a cyclohexane adduct, a trade name: EHPE3150, manufactured by DAICEL CO., Ltd. 30 parts, 15 parts of solid bisphenol type epoxy resin, 5 parts of liquid bisphenol type epoxy resin, photocationic polymerization initiator (hexafluoroantimony sulfonium salt, trade name: CPI-101A, manufactured by San-Apro Ltd.) 2.0 parts, 0.5 parts of a hindered phenol-based antioxidant (trade name: Songnox 1010, manufactured by Kosei Co., Ltd.), and 0.5 part of a phosphate ester antioxidant (HCA, manufactured by Sanko Co., Ltd.) were mixed in 65 parts of an organic solvent (ethyl lactate). After stirring at 110 ° C for heating, the solution was completely dissolved, and then cooled to room temperature (25 ° C), and then heated and pressure-filtered with a membrane filter having a diameter of 1.0 μm to prepare a cladding varnish (cladding) formed of a cladding material. Use epoxy resin composition). (Photosensitive film for preparing a cladding layer) A clad varnish was applied to a release-treated carrier film by a spreader (polyethylene film, trade name: Sunfort AQ4059, manufactured by Hitachi Chemical Co., Ltd.).

Next, the coated clad varnish was dried at 120 ° C for 10 minutes. Thereby, the clad varnish was dried to prepare a resin composition layer for cladding having a thickness of 40 μm.

Next, the release film (polyethylene film, trade name: Sunfort AQ4059, manufactured by Hitachi Chemical Co., Ltd.) was released using a laminator (condition: 40 ° C, transport speed 0.5 m/min, adhesion pressure 0.3 MPa). It is bonded to the resin composition layer for cladding.

The photosensitive film for cladding was prepared in the above manner. Examples 1 to 10 (Modified core varnish)

The cresol novolac type epoxy resin (epoxy equivalent: 194 to 208 g/eq.) and the solid bisphenol A type epoxy resin (epoxy equivalent of 600 to 700 g/eq) represented by the above formula (1) under light-shielding conditions. .), liquid bisphenol A type epoxy resin (epoxy equivalent: 184 to 194 g/eq.), solid oxime-containing epoxy compound represented by the above chemical formula (2), photocationic polymerization initiator (hexafluoroantimony sulfonium salt) The hindered phenolic antioxidant and the phosphate ester antioxidant are mixed in an organic solvent (ethyl lactate) according to the formula shown in Table 1 and Table 2, and stirred at 110 ° C under heating to completely dissolve the mixture, and then cooled to a chamber. After heating (25 ° C), it was subjected to heat and pressure filtration using a membrane filter having a diameter of 1.0 μm to prepare a core varnish (core epoxy resin composition) formed of a core material.

Further, in Comparative Example 1, a liquid bisphenol A type epoxy resin was not added. Further, in Comparative Example 2, a solid bisphenol A type epoxy resin was not added. Further, in Comparative Example 3, a liquid bisphenol A type epoxy resin was not added and a liquid fluorene-containing epoxy compound was added instead of the solid fluorene-containing epoxy compound. (Photosensitive film for modulating a core) A photosensitive film for a core is prepared in the same manner as the photosensitive film for a cladding layer, except that the cladding varnish is replaced with a core varnish. The thickness of the core resin composition layer was 75 μm. (Production of Optical Waveguide) The cover film was peeled off from the photosensitive film for cladding, and the resin composition layer for cladding was bonded to the surface of the ruthenium wafer at 80 ° C and 0.3 MPa using a pressure laminator.

Next, the cladding resin composition layer was irradiated with ultraviolet light over the carrier film under an ultrahigh pressure mercury lamp at 3000 mJ/cm ² through a glass mask (thickness: 4.8 mm, no pattern). The ultraviolet light penetrates the carrier film to expose the cladding layer with the resin composition layer. Thereby, the cladding layer is cured with the resin composition layer.

Next, the carrier film was peeled off from the resin composition layer for cladding, and then heat-treated (prebaked) at 140 ° C for 10 minutes. Thereby, an under cladding layer is formed on the germanium wafer.

Next, the cover film was peeled off from the photosensitive film for a core, and the core fat composition layer was bonded to the surface of the under cladding layer at 80 ° C and 0.3 MPa using a pressure type bonding machine.

Next, a glass mask (thickness: 4.8 mm) in which a slit having a pattern of L (column) / S (pitch) = 50 μm / 200 μm and corresponding to the core portion was formed was used, and an ultrahigh pressure mercury lamp was used at 5000 mJ/cm ² . The core resin composition layer was irradiated with ultraviolet light over the carrier film under the conditions. The ultraviolet light transmits the carrier film to expose a portion of the core resin composition layer corresponding to the core layer. Thereby the core layer is hardened.

Next, the carrier film was peeled off from the core resin composition layer, and then heat-treated (prebaked) at 140 ° C for 10 minutes.

Then, development treatment is carried out in a developing solution (γ-butyrolactone) at room temperature to dissolve and remove the unexposed portion in the core resin composition layer.

Thereby, a core layer is formed on the lower cladding layer. The core layer was then sparged and dried at 120 ° C for 5 minutes.

The clad varnish was then applied to the undercladding layer by means of a spin coater so as to coat the core layer. The cladding varnish was dried at 130 ° C for 5 minutes. Thereby, a resin composition layer for cladding is formed. The thickness of the resin composition layer for cladding layer was 20 μm.

Further, ultraviolet light was irradiated under an ultrahigh pressure mercury lamp at 2000 mJ/cm ² through a glass mask (thickness: 4.8 mm, no pattern) to expose the cladding resin composition layer.

Then, the cladding layer was heat-treated (prebaked) with a resin composition layer at 140 ° C for 10 minutes. Thereby, an upper cladding layer is formed on the lower cladding layer.

The optical waveguide is modulated in the above manner. (assessment)

The following items were evaluated for the core epoxy resin composition (core varnish) of each of the examples and the comparative examples. The results are shown in Tables 1 and 2. [Patternity] In the modulated optical waveguides of the above-described examples and comparative examples, the shape of the core layer was confirmed by a CCD camera before the formation of the over cladding layer. And evaluated according to the following criteria. ○: A normal rectangular pattern (core portion) was formed in the core layer. Δ: A pattern (core) having a shape slightly different from that of the rectangle was formed in the core layer, but the following linear loss was not affected. X: A pattern (core) having a shape different from that of a rectangle was formed in the core layer, and the linear loss value described below was lowered. [Evaluation of loss of optical waveguide (linear loss)] Using the optical waveguide modulated in the above-described embodiments and comparative examples, light oscillated from a light source (850 nm VCSEL light source OP250, manufactured by Sanxi Co., Ltd.) was transmitted through a multimode fiber. (trade name: FFP-G120-0500 (50 μmM MF in diameter, NA = 0.2), manufactured by Sanke Co., Ltd.) was collected and incident on the core layer of the optical waveguide. Then, the light emitted from the core layer is condensed to a lens (trade name: FH14-11 (magnification 20, NA = 0.4), manufactured by Kiyoshi Optical Co., Ltd.), and the optical measurement system (trade name: Optical Multi Power Meter Q8221, ADVANTEST) CO. system) evaluates 6 channels. The linear loss is calculated from its average total loss. Then, from the calculated linear loss, the loss value per unit length was calculated by a cutback method and evaluated according to the following criteria. ○: The linear loss value is less than 0.045 dB/cm. △: The linear loss value is 0.045 dB/cm or more and 0.055 dB/cm or less. ×: The linear loss value exceeds 0.055 dB/cm. [Softness] The core varnish obtained in each of the examples and the comparative examples was applied onto a glass substrate, and then dried by heating at 130 ° C for 5 minutes to prepare a core composition layer having a thickness of about 70 μm. Next, using a mixed line (using an ultrahigh pressure mercury lamp and no band pass filter) for the core tree composition layer, a glass mask having a thickness of 4.8 mm (without pattern) is placed under 4000 mJ/cm ² with a wavelength of 365 nm. Exposure. The core layer was then prepared by heating at 140 ° C for 10 minutes. The core layer was peeled off from the glass substrate and bent at a radius of curvature to confirm the presence or absence of cracking of the core layer. And, the evaluation was performed based on the following criteria. ○: No crack occurred at a radius of curvature of 1 mm. △: No crack occurred at a curvature radius of 2 mm, but cracks occurred at a radius of curvature of 1 mm. ×: Cracks were generated at a radius of curvature of 2 mm. [Refractive Index] The core varnish obtained in each of the examples and the comparative examples was applied onto a crucible having a thickness of 0.8 mm by a spin coater, and then dried by heating at 130 ° C for 10 minutes to prepare a core-tree composition layer. Next, the core tree composition layer was mixed with a glass mask (without pattern) having a thickness of 4.8 mm at 4000 mJ/cm ² using a mixed line (using an ultrahigh pressure mercury lamp and no band pass filter) with reference to 365 nm illuminance. exposure. The core layer was then prepared by heating at 140 ° C for 10 minutes. Next, the refractive index of the core layer at a wavelength of 850 nm was confirmed by a ruthenium coupler (SPA-4000 model, manufactured by SAIRON TECHNOLOGY). And, the evaluation was performed based on the following criteria. ○: The refractive index at a wavelength of 830 nm was 1.584 or more. △: The refractive index at a wavelength of 830 nm was 1.583 or more and less than 1.584. ×: The refractive index at a wavelength of 830 nm is less than 1.583. [Dry Process Compliance] After the cover film was peeled off from the photosensitive film obtained by using each of the examples and the comparative examples, the core fat composition layer was bonded at 80 ° C and 0.3 MPa using a pressure laminator. To the surface of the PET substrate.

Next, over the carrier film, a mixture of wires (using an ultrahigh pressure mercury lamp and no band pass filter) was used for the core grease layer, and a glass mask having a thickness of 4.8 mm was placed under 5000 mJ/cm ² with reference to 365 nm illumination ( Exposure without pattern).

Further, the carrier film is peeled off from the core resin composition layer. The dry process suitability is then evaluated on the basis of the following criteria. ○: The cover film and the core fat composition layer were adhered to each other, and the cover film and the carrier film were individually peeled off from the core fat composition layer. △: The cover film and the core fat composition layer were lightly adhered but had no problem in handling, and the cover film and the carrier film were individually peeled off from the core fat composition layer. X: The cover film and the core fat composition layer are strong and the surface roughness is generated in the core fat composition layer when the cover film is peeled off, or the cover film is not adhered to the core fat composition layer. [Comprehensive evaluation] Based on the above evaluation results, a comprehensive evaluation is carried out based on the following criteria. ○: ○ is obtained in all evaluation items. △: One or more items of △ are evaluated in the evaluation item. ×: One or more items in the evaluation project are selected.

[Table 1-2]

In addition, the above-described invention is provided as an exemplified embodiment of the present invention, but is merely illustrative and should not be construed as limiting. Modifications of the present invention which are well known to those skilled in the art are also included in the scope of the appended claims.

Industrial Applicability The photosensitive epoxy resin composition for forming an optical waveguide core of the present invention and the photosensitive thin film for forming an optical waveguide core are suitably used as a core material which constitutes an optical waveguide which can be used in various industrial products. The optical waveguide of the present invention is suitably used for an opto-electric hybrid substrate that can be utilized in various industrial products. The optical waveguide manufacturing method of the present invention is suitable for fabricating an optical waveguide such as that which can be used for an opto-electric hybrid substrate.

1‧‧‧Photosensitive film for core

2‧‧‧ core resin layer

3‧‧‧ Carrier film

4‧‧‧ Cover film

7‧‧‧Opto-electric hybrid substrate

8‧‧‧ optical waveguide

9‧‧‧Electrical circuit substrate

10‧‧‧ core layer

11‧‧‧Under the cladding

12‧‧‧Upper cladding

13‧‧‧ core

14‧‧‧Mirror

15‧‧‧Metal support layer

16‧‧‧Basic insulation

17‧‧‧Conductor layer

18‧‧‧ Covering insulation

19‧‧‧ openings

20‧‧‧1st terminal

21‧‧‧ wiring

22‧‧‧2nd terminal

25‧‧‧Photomask

26‧‧‧ Strengthening film

31‧‧‧Under the cladding

32‧‧‧ dent

33‧‧·coating film

33A‧‧‧ coated surface

34‧‧‧Dry film

35‧‧‧ Carrier film

T1, T2‧‧‧ thickness

Fig. 1 is a cross-sectional view showing an embodiment of a photosensitive film for forming an optical waveguide core of the present invention. Fig. 2 is a plan view showing an embodiment of the opto-electric hybrid board of the present invention. Fig. 3 is a cross-sectional view showing the A-A of the opto-electric hybrid substrate shown in Fig. 2. Fig. 4 is a cross-sectional view showing the B-B of the opto-electric hybrid board shown in Fig. 2. 5, FIG. 5A to FIG. 5F are views showing a manufacturing step of the photovoltaic hybrid substrate shown in FIG. 3, FIG. 5A shows a step of forming a lower cladding layer, and FIG. 5B shows a step of attaching a core resin composition layer to the lower cladding layer. Fig. 5C shows a step of exposing the core resin composition layer, Fig. 5D shows a step of peeling the carrier film from the core resin composition layer, Fig. 5E shows a step of developing the core layer, and Fig. 5F shows a step of forming the over cladding layer. . In Fig. 6, Fig. 6A is an explanatory view for explaining a wet process. Fig. 6B is an explanatory view for explaining a dry process.

Claims (7)

A photosensitive epoxy resin composition for forming an optical waveguide core, comprising: a resin component and a photocationic polymerization initiator; wherein the resin component contains a cresol novolac epoxy resin having three or more epoxy groups, and has 2 A solid epoxy bisphenol epoxy resin having an epoxy group, a liquid bisphenol epoxy resin having two epoxy groups, and a solid oxime-containing epoxy compound. The photosensitive epoxy resin composition for forming an optical waveguide core according to claim 1, wherein the cresol novolac type epoxy resin, the solid bisphenol type epoxy resin, the liquid bisphenol type epoxy resin, and the aforementioned solid state are 100 parts by mass of the total of the oxime-containing epoxy compound, the content of the cresol novolac type epoxy resin is 45 parts by mass or more and 60 parts by mass or less, and the content of the solid bisphenol type epoxy resin is 15 parts by mass or more. The content ratio of the liquid bisphenol-type epoxy resin is 15 parts by mass or more and 25 parts by mass or less, and the content ratio of the solid fluorene-containing epoxy compound is 5 parts by mass or more and 15 parts by mass or less. A photosensitive film for forming an optical waveguide core, comprising a resin composition layer containing the photosensitive epoxy resin composition for forming an optical waveguide core according to claim 1. An optical waveguide comprising a core layer containing a cured product of a photosensitive epoxy resin composition for forming an optical waveguide core according to claim 1. The optical waveguide of claim 4 further comprising a cladding layer covering the core layer and having a refractive index of 1.554 or less. An opto-electric hybrid substrate comprising the optical waveguide of claim 4. A method for producing an optical waveguide, comprising the steps of: forming a lower cladding layer; and attaching the resin composition layer of the photosensitive film for forming an optical waveguide core according to claim 3 to the under cladding layer; The resin composition layer is exposed and developed to form a core layer on the under cladding layer, and an over cladding layer is formed on the under cladding layer so as to cover the core layer.