JP2006038962A - Optical waveguide with protective layer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical waveguide which has high wet heat resistant stability of a refractive index while having a cladding layer and a core layer which comprise a hygroscopic epoxy resin. <P>SOLUTION: In an optical waveguide obtained by sequentially forming on a substrate a lower cladding layer, a core layer and an upper cladding layer, at least the core layer and the upper cladding layer comprise an epoxy resin and a protective layer comprising metallic foil, a fluorocarbon resin or an inorganic material is formed on the upper cladding layer. The objective optical waveguide is thus obtained. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an optical waveguide. More specifically, the present invention relates to an optical waveguide that is superior in refractive index moisture resistance heat resistance while both an upper clad layer and a core layer are made of a hygroscopic epoxy resin.

  With the practical application of optical communication systems through the development of optical fibers, development of a wide variety of optical communication devices using optical waveguide structures is required. In recent years, the use of various resins has been studied as a material for this optical waveguide. Among them, epoxy resin is excellent in transparency before and after the visible region. ,Proposed.

In particular, if a photopolymerizable epoxy resin composition containing a photopolymerization initiator is used, a polymer optical waveguide has already been manufactured using the fact that a required pattern can be easily formed by a wet process. It is known (see Patent Document 1). However, the epoxy resin has poor moisture resistance, and the epoxy resin forming the upper clad layer and the core layer easily absorbs moisture due to the high polarity of the hydroxyl group, which is a reaction product of the epoxy group, and therefore the refractive index changes. Since it is easy, it is not sufficient in the heat-and-moisture stability of a refractive index, and there exists a problem in reliability.
JP-A-10-268152

  SUMMARY OF THE INVENTION An object of the present invention is to provide an optical waveguide having a refractive index and a high resistance to moist heat, while having an upper clad layer and a core layer made of an epoxy resin having a hygroscopic property.

  According to the present invention, in an optical waveguide in which a lower clad layer, a core layer, and an upper clad layer are formed in this order on a substrate, at least the core layer and the upper clad layer are made of epoxy resin, and the upper clad layer An optical waveguide having a protective layer made of a metal foil, a fluororesin or an inorganic material is provided.

  The optical waveguide according to the present invention is provided with a low moisture-permeable protective layer made of metal foil, fluororesin or inorganic material on the upper clad layer, and the upper clad layer is not exposed to the outside. Therefore, the optical waveguide according to the present invention is excellent in moist heat resistance of the refractive index and has high reliability. .

  The optical waveguide according to the present invention is an optical waveguide in which a lower clad layer, a core layer, and an upper clad layer are formed on a substrate in this order. At least the core layer and the upper clad layer are made of epoxy resin, and the upper clad A protective layer made of a metal foil, a fluororesin or an inorganic material is formed on the layer.

  Such an optical waveguide with a protective layer, for example, is generally used except that the core layer is formed by directly patterning this using the photosensitivity of the photopolymerizable epoxy resin composition, as described later. Therefore, a planar optical waveguide, a ridge type optical waveguide, a buried type optical waveguide, etc. can be manufactured by the same method. In the present invention, the lower clad layer, the core layer, and the upper clad layer are preferably all made of epoxy resin, but the lower clad layer may be made of other resin.

  In the optical waveguide with a protective layer according to the present invention, the substrate is not particularly limited. For example, a silicon substrate, a quartz substrate, a metal foil, a glass plate, a polymer film, or the like is used. As conventionally known, a photopolymerizable epoxy resin composition is applied on such a substrate, dried, and then irradiated with ultraviolet rays to cure the epoxy resin. A lower cladding layer made of can be formed.

  In the present invention, in order to form the core layer and the upper clad layer from an epoxy resin, for example, a photopolymerizable epoxy resin composition may be used and this may be directly patterned. The photopolymerizable epoxy resin composition comprises an epoxy resin and a photopolymerization initiator. By irradiating such a photopolymerizable epoxy resin composition with light, particularly ultraviolet rays, photopolymerization is performed on the epoxy resin, that is, It can be photocured.

  In the present invention, the epoxy resin may be any epoxy resin regardless of whether it is aromatic or aliphatic. Among them, the general formula is that the obtained optical waveguide is excellent in heat resistance and flexibility. (I)

(In the formula, R ₁ to R ₄ each independently represent a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, R ₅ and R ₆ each independently represent a hydrogen atom or a methyl group, and n represents 0 to 10) Indicates a range integer.)
What is represented by these is used preferably.

In the epoxy resin represented by the general formula (I), examples of the alkyl group represented by R ₁ to R ₄ include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, s-butyl, Examples include t-butyl, n-pentyl, neopentyl, and n-hexyl.

According to the present invention, among the epoxy resin represented by the general formula (I), a R ₆ are all hydrogen atoms from R _1, it is preferably used n is 0 or 1. In the general formula (I), the epoxy resin in which R ₁ to R ₆ are all hydrogen atoms and n is 1 is bisphenoxyethanol fluorenediglycidyl ether (epoxy equivalent 320), and the epoxy resin in which n is 0 is Bisphenol full orange glycidyl ether (epoxy equivalent 234).

  In the present invention, the photopolymerizable epoxy resin composition contains such an epoxy resin in the range of 50 to 99.9% by weight, preferably 80 to 99% by weight. In the photopolymerizable epoxy resin composition, when the proportion of the epoxy resin is less than 50% by weight, for example, when the photopolymerizable epoxy resin composition is applied on a substrate, it may be difficult to form a film. On the other hand, in the photopolymerizable epoxy resin composition, when the proportion of the epoxy resin is more than 99.9% by weight, the proportion of the photopolymerization initiator is too small, and the photocuring of the epoxy resin does not occur even when irradiated with light. May be insufficient.

As the photopolymerization initiator, a photoacid generator known as a photocationic polymerization initiator for epoxy resins is preferably used. In the present invention, the photoacid generator is not particularly limited, and conventionally known photoacid generators, for example, onium salts are appropriately used. Examples of onium salts include diazonium salts, sulfonium salts, iodonium salts, phosphonium salts, selenium salts, and the like. Examples of these counter ions include CF ₃ SO ₃ ⁻ , BF ₄ ⁻ , PF ₆ ⁻ , AsF ₆ ⁻ , SbF ₆ ^{− and the} like.

  Therefore, as specific examples of the photoacid generator, for example, 4,4-bis [di (β-hydroxyethoxy) phenylsulfinio] phenyl sulfide-bis-hexafluoroantimonate, allylsulfonium hexafluorophosphate, triphenyl Sulfonium triflate, 4-chlorobenzenediazonium hexafluorophosphate, triphenylsulfonium hexafluoroantimonate, triphenylsulfonium hexafluorophosphate, (4-phenylthiophenyl) diphenylsulfonium hexafluoroantimonate, (4-phenylthiophenyl) diphenylsulfonium Hexafluorophosphate, bis [4- (diphenylsulfonio) phenyl] sulfide-bis-hexafluoroantimonate, bis [4 (Diphenylsulfonio) phenyl] sulfide-bis-hexafluorophosphate, (4-methoxyphenyl) diphenylsulfonium hexafluoroantimonate, (4-methoxyphenyl) phenyliodonium hexafluoroantimonate, bis (4-t-butylphenyl) Examples thereof include iodonium hexafluorophosphate, benzyltriphenylphosphonium hexafluoroantimonate, and triphenyl selenium hexafluorophosphate. These photoacid generators may be used alone or in combination of two or more.

  In the present invention, the photopolymerizable epoxy resin composition usually contains such a photoacid generator in the range of 0.1 to 10 parts by weight, preferably 0.5 to 100 parts by weight of the epoxy resin. In the range of ˜5 parts by weight.

  Furthermore, according to the present invention, the photopolymerizable epoxy resin composition contains various components such as a reactive oligomer and a diluent as necessary, in addition to the epoxy resin and the photoacid generator. It may be. Examples of the reactive oligomer include epoxy (meth) acrylate, urethane acrylate, butadiene acrylate, oxetane compounds, and the like. Preferably, oxetane compounds are used. The addition of a small amount of the oxetane compound can promote the curing of the photopolymerizable epoxy resin composition. Specific examples of such oxetane compounds include, for example, 3-ethyl-3-hydroxymethyloxetane, 3-ethyl-3- (phenoxymethyl) oxetane, bis (1-ethyl- (3-oxetanyl) methyl) ether, 3-ethyl-3- (2-ethylhexylmethyl) oxetane and the like can be mentioned. These reactive oligomers may be used alone or in combination of two or more. When such a reactive oligomer is blended in the photopolymerizable epoxy resin composition, the proportion thereof is usually 100 parts by weight or less, preferably 5 to 100 parts by weight with respect to 100 parts by weight of the epoxy resin. Part range.

  Examples of the diluent include alkyl monoglycidyl ether having 2 to 25 carbon atoms (for example, butyl glycidyl ether, 2-ethylhexyl glycidyl ether, etc.), butanediol diglycidyl ether, 1,6-hexanediol diglycidyl ether, Neopentyl glycol diglycidyl ether, dodecanediol diglycidyl ether, pentaethyltriol polyglycidyl ether, trimethylolpropane polyglycidyl ether, glycerol polyglycidyl ether, phenyl glycidyl ether, resorching glycidyl ether, pt-butylphenyl glycidyl ether, allyl Glycidyl ether, tetrafluoropropyl glycidyl ether, octafluoropropyl glycidyl ether, dodecaful Examples include lopentyl glycidyl ether, styrene oxide, 1,7-octadiene diepoxide, limonene diepoxide, limonene monooxide, α-pinene epoxide, β-pinene epoxide, cyclohexene epoxide, cyclooctene epoxide, vinylcyclohexene oxide, etc. it can.

  However, considering the heat resistance and transparency of the resulting cured product, for example, 3,4-epoxycyclohexenylmethyl-3 ′, 4′-epoxycyclohexenecarboxylate, 3,4-epoxycyclohexenylethyl-8, 4-epoxycyclohexenecarboxylate, vinylcyclohexene dioxide, allylcyclohexene dioxide, 8,4-epoxy-4-methylcyclohexyl-2-propylene oxide, bis (3,4-epoxycyclohexyl) ether, etc. in the molecule Epoxy compounds having the formula structure are preferably used. These diluents may be used alone or in combination of two or more. When such a diluent is blended in the photopolymerizable epoxy resin composition, the amount is usually 200 parts by weight or less, preferably 5 to 200 parts by weight with respect to 100 parts by weight of the epoxy resin.

  A photopolymerizable epoxy resin composition can be obtained as a varnish by dissolving and mixing the reactive oligomer or diluent in a solvent together with the epoxy resin and the photoacid generator, if necessary. The solvent is not particularly limited. For example, 2-butanone, cyclohexanone, N, N-dimethylacetamide, diglyme, diethylene glycol methyl ethyl ether, propylene glycol methyl acetate, propylene glycol monomethyl ether, tetramethyl furan , Dimethoxyethane and the like are preferably used. These solvents may be used alone or in combination of two or more. An appropriate amount of such a solvent is used so as to have an appropriate viscosity so that the resulting photopolymerizable epoxy resin composition can be easily applied. However, without using such a solvent, the above-mentioned diluent can be used in place of the solvent, and other components can be dissolved and mixed in the diluent to obtain a photopolymerizable epoxy resin composition as a varnish. it can.

In order to photocur the photopolymerizable epoxy resin composition, for example, a light source such as a low pressure mercury lamp, a high pressure mercury lamp, or an ultrahigh pressure mercury lamp is used to irradiate the resin layer made of the photopolymerizable epoxy resin composition with ultraviolet rays. Bayoku, the dose of ultraviolet radiation is typically in the range of 10 to 10000 mJ / cm ^2, preferably in the range of 50 to 3000 mJ / cm ^2. In the case of obtaining a clad layer or a core layer with high hardness, it is preferable that heating (post-exposure heating) is performed after light irradiation to accelerate and complete the crosslinking reaction of the epoxy resin.

  Below, an example of the manufacturing process of the optical waveguide with a protective layer by this invention is demonstrated with reference to FIG. First, as shown in FIG. 1 (A), a solution of a photopolymerizable epoxy resin composition that gives an epoxy resin having a refractive index higher than that of the substrate is applied onto the substrate 1 and dried to form a resin layer. The lower cladding layer 2 made of an epoxy resin is formed by irradiating this with ultraviolet rays and, if necessary, heating after exposure to a temperature in the range of 60 to 200 ° C. in air.

  Next, a solution of a photopolymerizable epoxy resin composition that gives an epoxy resin having a higher refractive index than that of the lower clad layer 2 is applied and dried to form a resin layer 3, and then FIG. As shown in FIG. 3, a glass mask 4 is placed on the resin layer 3 so as to obtain a desired pattern, and ultraviolet rays are irradiated from above to expose the resin layer according to the pattern. Next, in order to complete the photoreaction in this resin layer, it is usually heated after exposure as described above. Then, after developing with a developing solution and processing it into a predetermined pattern, the pattern made of an epoxy resin is formed as a core layer 5 as shown in FIG. To do. Next, in the same manner as the formation of the lower clad layer, as shown in FIG. 1D, an upper clad layer 6 made of an epoxy resin having a lower refractive index is formed on the core layer 5, Thus, an embedded optical waveguide is obtained. Thus, after manufacturing an optical waveguide, as shown in FIG.1 (E), the protective layer 7 is formed on the said upper clad layer, and the optical waveguide with a protective layer by this invention is obtained.

  The method of applying the solution of the photopolymerizable epoxy resin composition on the substrate or the core layer and applying the solution of the photopolymerizable epoxy resin composition on the lower clad layer is not particularly limited. For example, a general film forming method such as a spin coating method or a casting method can be used. Moreover, as a developing solution for the above development, an organic solvent, an alcohol, or an alkaline aqueous solution is usually used.

  An example of such an optical waveguide will be described in detail. The lower cladding layer and the upper cladding layer are made of an epoxy resin having a refractive index comparable to that of the optical fiber in order to increase the coupling efficiency with the optical fiber. The refractive index of such an epoxy resin is usually in the range of 1.52 to 1.65. Further, the film thickness of the lower clad layer is, for example, about 5 to 50 μm, and the film thickness of the upper clad layer is, for example, about 5 to 100 μm. The film thickness of the core layer is, for example, about 20 to 100 μm, and the width is also patterned to about 20 to 100 μm. The refractive index of the core layer is about 2% larger than that of the lower cladding layer and the upper cladding layer.

  According to this invention, the said protective layer consists of metal foil, a fluororesin, or an inorganic substance. For example, the metal foil can be directly heated and fused to the surface of the upper cladding layer to form a protective layer. The heating and fusing temperature at this time is preferably higher than the softening point or glass transition temperature of the epoxy resin forming the upper cladding layer. Moreover, metal foil can also be affixed on the surface of an upper clad layer via an adhesive agent, for example, to form a protective layer. Here, the adhesive is not particularly limited as long as it can adhere the protective layer to the upper clad layer with good adhesion, but for example, thermosetting adhesion in which styrene-butadiene rubber and epoxy resin are combined. An agent, a thermoplastic polyimide resin, or the like is preferably used. In addition to these methods, a metal foil may be formed on the upper cladding layer by, for example, vapor deposition. Further, chemical plating may be used in combination. As the metal foil for such a protective layer, for example, aluminum, copper, nickel, iron-nickel alloy or the like is used, and among them, copper foil is preferably used from the viewpoint of economy and handling properties.

  The protective layer may be a coating made of a fluororesin. The protective layer made of a fluororesin is formed, for example, by thermocompression bonding a fluororesin sheet or film to the surface of the upper cladding layer, or by bonding the surface of the upper cladding layer with an appropriate primer. Can do. Examples of such fluororesin sheets and films include polytetrafluoroethylene (PTFE), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (perfluoroalkoxy resin (PFA)), and tetrafluoroethylene-hexafluoropropylene copolymer (FEP). Tetrafluoroethylene-perfluoroalkyl vinyl ether-hexafluoropropylene copolymer (EPE), tetrafluoroethylene-ethylene or propylene copolymer (ETE), polychlorotrifluoroethylene resin (PCTFE), ethylene-chlorotrifluoroethylene copolymer (ECTFE), Examples thereof include those made of vinylidene fluoride resin (PVDF), vinyl fluoride resin (PVF), and the like.

  Also, vinyl fluoride resin (PVDF), tetrafluoroethylene-ethylene copolymer, vinylidene fluoride-hexafluoropropylene copolymer, etc. can be used as ketone solvents such as methyl ethyl ketone and cyclohexanone, and aprotic polar solvents such as dimethylacetamide and dimethylformamide. It can be dissolved to form a solution, which can be applied to the surface of the upper cladding layer and dried to form a coating made of these fluororesins as a protective layer. Furthermore, as another method, a fluororesin dispersion is applied to the surface of the upper clad layer and then baked to form a film, which can be used as a protective layer. Among these various fluororesins, according to the present invention, vinylidene fluoride resin (PVDF) is particularly preferably used in terms of hygroscopicity and handling properties.

  Furthermore, the protective layer may be an inorganic layer. In the present invention, the inorganic layer is not particularly limited as long as it has a water vapor barrier property. Accordingly, specific examples of such an inorganic layer include an oxide, nitride, or oxynitride layer containing at least one of silicon, aluminum, indium, tin, zinc, titanium, and the like. Especially, it is preferable that an inorganic substance layer consists of a layer of a silicon oxide or a silicon oxynitride so that a protective layer may have water vapor | steam barrier property and transparency. In order to form such an inorganic layer, for example, a physical vapor deposition method (PVD method) such as a vacuum deposition method, a sputtering method, or an ion plating method, a plasma chemical vapor deposition method, a thermal chemical vapor deposition method, or the like. A chemical vapor deposition method (CVD) method such as a method can be used.

  EXAMPLES The present invention will be described below with reference to examples, but the present invention is not limited to these examples.

Reference example 1
83 parts by weight of bisphenoxyethanol fluorenediglycidyl ether and 17 parts by weight of diluent 3,4-epoxycyclohexenylmethyl-3 ′, 4′-epoxycyclohexenecarboxylate and photoacid generator 4,4-bis [di (β-hydroxy Ethoxy) phenylsulfinio] phenylsulfide-bis-hexafluoroantimonate 50 wt% propylene carbonate solution (2 parts by weight) was dissolved in cyclohexanone (100 parts by weight) to obtain a photopolymerizable epoxy resin composition as varnish A. The refractive index of the epoxy resin obtained by curing the varnish A at a measurement wavelength of 633 nm was 1.585.

Reference example 2
67 parts by weight of bisphenoxyethanol fluorange glycidyl ether, 23 parts by weight of bisphenol fluorange glycidyl ether and 2 parts by weight of the same photoacid generator as in Reference Example 1 are dissolved in 90 parts by weight of cyclohexanone to obtain a photopolymerizable epoxy resin composition. Obtained as B. The refractive index of the epoxy resin obtained by curing this varnish B at a measurement wavelength of 633 nm was 1.617.

Example 1
Varnish A was applied on a 10 cm × 10 cm glass plate by a spin coating method and dried by heating at 90 ° C. for 15 minutes to form a resin layer. Thereafter, the entire surface of the resin layer was irradiated with ultraviolet rays at an irradiation amount of 2000 mJ / cm ² and then heated at 170 ° C. for 30 minutes to form a lower cladding layer having a thickness of 30 μm (see FIG. 1A). ).

Next, varnish B was applied on the lower clad layer by a spin coating method, followed by heating and drying at 90 ° C. for 15 minutes to form a resin layer (see FIG. 1C). Next, using a photomask (synthetic quartz-based chromium mask) having a linear optical waveguide pattern with a width of 50 μm, a contact exposure method was used to irradiate ultraviolet rays at a dose of 2000 mJ / cm ² (FIG. 1B )reference). At this time, the photomask was directly brought into contact with the resin layer, but adhesion of the resin to the photomask was not observed after exposure.

  Then, after exposure and heating at 90 ° C. for 60 minutes, the film was immersed and developed in an acetonitrile-based developer to form a resin layer (see FIG. 1 (e)). Thereafter, the resin layer was heated at 170 ° C. for 30 minutes to form a core layer having a thickness of 50 μm and a width of 50 μm and a rectangular cross section (see FIG. 1C).

Next, varnish A was applied on the lower clad layer including the core layer by a spin coat method, followed by heating and drying at 90 ° C. for 15 minutes to form a resin layer. Thereafter, the entire surface of the resin layer was irradiated with ultraviolet rays at a dose of 2000 mJ / cm ² , and then heated at 170 ° C. for 30 minutes to form an upper cladding layer having a thickness of 80 μm (see FIG. 1D). Thus, a multi-mode optical waveguide having a relative refractive index Δ = 2.0% was obtained.

  Next, a copper foil having a thickness of 19 μm was prepared by applying an adhesive made of SBR rubber and epoxy resin to a thickness of 10 μm on one side. The copper foil is bonded onto the upper clad layer and dried at 100 ° C. for 2 hours to form a protective layer made of a metal foil on the upper clad layer. Thus, an embedded optical waveguide with a protective layer is formed. Was obtained (see FIG. 1E).

  After the end face treatment of this optical waveguide, the light propagation loss was measured by the cut-back method through light having a wavelength of 850 nm, and it was 0.18 dB / cm. Next, the loss value after leaving this embedded optical waveguide with a protective layer in an atmosphere of a temperature of 60 ° C. and a relative humidity of 95% for 168 hours was 0.19 dB / cm.

Example 2
An adhesive made of SBR rubber and an epoxy resin was applied to one surface of a 50 μm thick iron-nickel alloy (SUS) foil to a thickness of 15 μm. This metal foil is laminated on the upper clad layer of the optical waveguide obtained in Example 1, and thermocompression bonded in a vacuum at 100 ° C. for 15 minutes to form a protective layer made of the metal foil on the upper clad layer, In this way, an embedded optical waveguide with a protective layer was obtained.

  After the end face treatment of this optical waveguide, the light propagation loss was measured by the cut-back method through light having a wavelength of 850 nm, and it was 0.18 dB / cm. Next, the loss value after this embedded optical waveguide with a protective layer was left for 168 hours in an atmosphere having a temperature of 121 ° C. and a relative humidity of 100% was 0.20 dB / cm.

Example 3
A vinylidene fluoride resin was dissolved in dimethylformamide at a concentration of 20% by weight to obtain a solution. The above solution was applied on the upper clad layer of the optical waveguide obtained in Example 1, dried at 120 ° C. for 5 hours in a vacuum atmosphere, and a protective layer having a thickness of 10 μm made of vinylidene fluoride resin on the upper clad layer. Thus, an embedded optical waveguide with a protective layer was obtained.

  After the end face treatment of this optical waveguide, the light propagation loss was measured by the cut-back method through light having a wavelength of 850 nm, and it was 0.22 dB / cm. Next, the loss value after this embedded optical waveguide with a protective layer was left for 168 hours in an atmosphere at a temperature of 60 ° C. and a relative humidity of 90% was 0.23 dB / cm.

Example 4
A silicon oxide vapor deposition film having a thickness of 30 nm was formed on the upper clad layer of the optical waveguide obtained in Example 1 by using a plasma CVD method. Thus, an embedded optical waveguide with a protective layer was obtained. . After the end face treatment of this optical waveguide, the light propagation loss was measured by the cut-back method through light having a wavelength of 850 nm, and it was 0.18 dB / cm. Next, the loss value after leaving this buried optical waveguide with a protective layer in an atmosphere at a temperature of 85 ° C. and a relative humidity of 85% for 168 hours was 0.18 dB / cm.

Example 5
A silicon oxide vapor deposition film having a thickness of 20 nm was formed on the upper cladding layer of the optical waveguide obtained in Example 1 by using a plasma CVD method. Thus, an embedded optical waveguide with a protective layer was obtained. . After the end face treatment of this optical waveguide, the light propagation loss was measured by the cutback method through light having a wavelength of 850 nm, and it was 0.19 dB / cm. Next, the loss value after leaving this embedded optical waveguide with a protective layer in an atmosphere at a temperature of 60 ° C. and a relative humidity of 90% for 168 hours was 0.19 dB / cm.

Comparative Example 1
Without forming a protective layer on the upper clad layer of the optical waveguide obtained in Example 1, the loss value after standing in an atmosphere at a temperature of 121 ° C. and a relative humidity of 100% for 168 hours was 0.45 dB / cm. It was.

(A) to (E) are diagrams showing an example of a manufacturing process of an optical waveguide provided with a protective layer according to the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Board | substrate 2 ... Lower clad layer 3 ... Resin layer which consists of photopolymerizable epoxy resins 4 ... Glass mask 5 ... Core layer 6 ... Upper clad layer 7 ... Protective layer

Claims (5)

  In an optical waveguide in which a lower clad layer, a core layer, and an upper clad layer are formed in this order on a substrate, at least the core layer and the upper clad layer are made of an epoxy resin, and a metal foil, fluorine is provided on the upper clad layer. An optical waveguide having a protective layer made of a resin or an inorganic substance. Epoxy resin is represented by the general formula (I)

(In the formula, R ₁ to R ₄ each independently represent a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, R ₅ and R ₆ each independently represent a hydrogen atom or a methyl group, and n represents 0 to 10) Indicates a range integer.)
The optical waveguide according to claim 1, which is represented by:   The optical waveguide according to claim 1, wherein the metal foil is a copper foil or an iron-nickel alloy foil.   The optical waveguide according to claim 1, wherein the fluororesin is a vinylidene fluoride resin. The optical waveguide according to claim 1, wherein the inorganic substance is an oxide, nitride, or oxynitride of silicon.

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