JP2010191289A - Method of manufacturing optical waveguide - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing an optical waveguide which has full optical transmission capability. <P>SOLUTION: The method of manufacturing the optical waveguide is provided for forming a pattern of the optical waveguide by means of photolithography, in which predetermined parts of a photosensitive resin layer are irradiated with light then the parts which are not irradiated with light are removed by a developing solution. The method includes a process in which a core layer made of a core material having solubility in the developing solution is formed; a process in which a cladding layer made of a photosensitive cladding material having solubility in the developing solution, before irradiated with light is formed on the core layer; and a process in which a pattern on the cladding layer is formed, by removing the parts which is not irradiated with light by using the developing solution after the predetermined parts on the cladding layer are irradiated with light, and the pattern on the core layer is formed by using the cladding layer on which the pattern is formed as a resist mask, and thus the optical waveguide having the core 10 and the upper cladding layer 11 formed on the core is obtained. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method for manufacturing an optical waveguide, and more particularly to a method for manufacturing an optical waveguide that can be suitably used in a flexible optical wiring board, an optoelectric composite wiring board, and the like.

  In recent years, with the rapid advancement in performance and functionality of electronic devices, there has been a demand for higher capacity and higher speed of transmission information in electronic devices. High frequency is progressing. On the other hand, as electronic circuits become highly integrated and electrical signals have a higher frequency, electrical signal crosstalk and noise are generated, characteristic impedance is difficult to adjust, and losses occur in the high frequency range. However, it has been difficult to improve these problems by a technique related to information transmission using electrical signals. Therefore, information transmission using light using an optical waveguide has been studied as a method of information transmission that can solve these problems.

  In electronic devices such as portable devices and small devices, various components are densely arranged, and therefore wiring must be performed so as to sew a narrow gap between the components. For this reason, flexible wiring boards are widely used as wiring boards, and optical waveguides that can be suitably used in such flexible optical wiring boards and photoelectric composite wiring boards are required. ing.

  As such an optical waveguide, for example, International Publication No. 2008/007673 pamphlet (Patent Document 1) discloses an optical waveguide using a specific siloxane-modified polyimide resin as a material of the optical waveguide.

International Publication No. 2008/007673 Pamphlet

  However, in the optical waveguide as described in Patent Document 1, it is necessary to use a photosensitive material as the core material in order to form the pattern of the optical waveguide. In such a case, the photocuring component such as a monomer having an unsaturated bond or a cured product thereof and the siloxane-modified polyimide resin in the core material take a phase-separated structure, resulting in poor transparency of the formed core. However, the optical waveguide as described in Patent Document 1 is not always sufficient in that the optical transmission capability of the optical waveguide becomes insufficient.

  The present invention has been made in view of the above-described problems of the prior art, and an object of the present invention is to provide an optical waveguide manufacturing method capable of manufacturing an optical waveguide having sufficient optical transmission capability.

  As a result of intensive studies to achieve the above object, the inventors of the present invention formed a core layer and a cladding layer on the surface of the core layer, and then irradiated light to a predetermined portion of the cladding layer, Forming a pattern of the clad layer by removing a portion that is not irradiated with light by the developer, and forming the pattern of the core layer by the developer using the clad layer having the pattern formed as a resist mask; Even when a non-photosensitive core material is used, a core layer pattern can be formed, and an optical waveguide having sufficient optical transmission capability can be manufactured as described below. As a result, the present invention has been completed.

That is, the method for producing an optical waveguide according to the present invention includes forming an optical waveguide pattern by photolithography in which a predetermined portion of a photosensitive resin layer is irradiated with light and then a portion not irradiated with light is removed with a developer. A manufacturing method of
Forming a core layer made of a core material having solubility in the developer;
Forming a clad layer made of a clad material having photosensitivity and solubility in the developer before light irradiation on the surface of the core layer;
After irradiating a predetermined portion of the clad layer with light, the portion not irradiated with the developer is removed to form a pattern of the clad layer, and the development is performed using the clad layer with the pattern formed as a resist mask. Forming a pattern of the core layer with a liquid to obtain an optical waveguide comprising a core and an upper clad formed on the core;
It is the method characterized by including.

  In the method for producing an optical waveguide of the present invention, the clad material preferably contains a siloxane-modified polyimide resin or a precursor thereof, a monomer having an unsaturated bond, and a photopolymerization initiator.

  Furthermore, in the method for producing an optical waveguide according to the present invention, the core material preferably contains a siloxane-modified polyimide resin or a precursor thereof. Moreover, it is preferable that the said core material does not contain a photoinitiator substantially. Further, the core material may contain a monomer having an unsaturated bond. In such a case, the content of the monomer is based on 100 parts by mass of the siloxane-modified polyimide resin or its precursor. Is preferably in the range of 1 to 30 parts by mass.

  In the method for producing an optical waveguide of the present invention, the developer is preferably a sodium carbonate aqueous solution.

  Furthermore, in the method for manufacturing an optical waveguide of the present invention, it is preferable that the thickness of the cladding layer is 1 to 40 μm.

  In addition, according to the manufacturing method of the optical waveguide of this invention, it becomes possible to provide the manufacturing method of the optical waveguide which can manufacture the optical waveguide which has sufficient optical transmission capability. That is, according to the method for manufacturing an optical waveguide of the present invention, a core layer pattern can be formed even when a non-photosensitive core material is used. It is not necessary to contain a monomer having an unsaturated bond for imparting photosensitivity or a photopolymerization initiator. And, the transparency of the core deteriorates due to the phase separation structure of the monomer having the unsaturated bond to be photocured, the polymer by the photopolymerization initiator and the siloxane-modified polyimide resin in the core material, In the core material used in the present invention, the content of the monomer having an unsaturated bond and the photopolymerization initiator can be drastically reduced as compared with the core material in the conventional production method. Therefore, the core of the optical waveguide obtained by the method for manufacturing an optical waveguide of the present invention is excellent in transparency and has a sufficient optical transmission capability.

  ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to provide the manufacturing method of the optical waveguide which can manufacture the optical waveguide which has sufficient optical transmission capability.

It is a schematic diagram which shows the state which formed the lower clad and the core layer on the board | substrate. It is a schematic diagram which shows the state which formed the clad layer on the core layer shown in FIG. It is a schematic diagram which shows the state which irradiated the ultraviolet-ray to the predetermined location of the clad layer shown in FIG. It is a schematic diagram which shows the optical waveguide in which the core and the upper clad formed on the core were formed.

  Hereinafter, the present invention will be described in detail with reference to preferred embodiments thereof.

The optical waveguide manufacturing method of the present invention is a method for manufacturing an optical waveguide in which an optical waveguide pattern is formed by photolithography in which a predetermined portion of a photosensitive resin layer is irradiated with light and then a portion not irradiated with light is removed with a developer. A method,
A step of forming a core layer made of a core material having solubility in the developer (first step);
Forming a clad layer made of a clad material having photosensitivity and solubility in the developer before light irradiation on the surface of the core layer (second step);
After irradiating a predetermined portion of the clad layer with light, the portion not irradiated with the developer is removed to form a pattern of the clad layer, and the development is performed using the clad layer with the pattern formed as a resist mask. Forming a pattern of the core layer with a liquid to obtain an optical waveguide comprising a core and an upper clad formed on the core (third step);
It is the method characterized by including.

  First, the clad material and the core material used in the method for producing an optical waveguide of the present invention will be described.

  The clad material used in the present invention has photosensitivity and has solubility in a developer used for forming an optical waveguide pattern before light irradiation. Photosensitivity refers to the property of initiating reaction and photocuring when irradiated with specific light. The clad material preferably contains a siloxane-modified polyimide resin or a precursor thereof, a monomer having an unsaturated bond, and a photopolymerization initiator.

  The siloxane-modified polyimide resin used in the present invention is preferably a siloxane-modified polyimide resin having repeating units represented by the following general formulas (1) and (2). In addition, the precursor of the siloxane-modified polyimide resin used in the present invention is a siloxane-modified compound having a repeating unit represented by the following general formulas (1) and (2) by performing a dehydration ring-closing reaction by heat treatment or dehydration treatment. It is preferable that it is a precursor used as a polyimide resin.

In the general formulas (1) and (2), Ar ₁ and Ar ₂ each represent a tetravalent aromatic group represented by the following general formula (3), and Ar ₃ represents the following general formula (4) or the following general formula The divalent aromatic group represented by Formula (5) is shown. Furthermore, R ₃ is a divalent hydrocarbon group having 2 to 6 carbon atoms, preferably an alkylene group having 2 to 6 carbon atoms. R ₄ represents a monovalent hydrocarbon group having 1 to 6 carbon atoms, preferably a methyl group or a phenyl group. M represents an integer of 1 to 50 (preferably 5 to 30). If m is less than 1, the reduction in elastic modulus (flexibility) is insufficient. On the other hand, if it exceeds 50, the reactivity with tetracarboxylic dianhydride is lowered and the molecular weight of the polymer is lowered. Decreases. Here, when a plurality of R ₃ and R ₄ are present in one repeating unit, they may be the same or different. In addition, when a plurality of repeating units are present in one molecule, Ar ₁ , Ar ₂ , Ar ₃ , and R _{3 to} R ₄ may be the same or different.

In the general formulas (3), (4) and (5), X and Y are each a single bond or a divalent hydrocarbon group having 1 to 15 carbon atoms, O, S, CO, SO ₂ and CONH. X represents a divalent group selected from the group consisting of a single bond or a divalent hydrocarbon group having 1 to 15 carbon atoms, O and CO. Is preferred. Further, Y is preferably a divalent group selected from the group consisting of a single bond or O, CO and SO _2. Moreover, as a bivalent hydrocarbon group, a C1-C6 alkylene group (an alkylidene group is included) and a phenylene group are mentioned. Further, R ₁ represents a monovalent hydrocarbon group having 1 to 6 carbon atoms, and R ₁ is preferably an alkyl group, alkenyl group, cycloalkyl group or phenyl group having 1 to 6 carbon atoms, It is more preferable that it is a 1-3 alkyl group, a vinyl group, or a phenyl group. Moreover, in the said General formula (4) and (5), although n shows the integer of 0-4, it is preferable that n is 0-2, and it is more preferable that it is 0. As described above, in the general formula (1), Ar ₃ is a divalent aromatic group represented by the general formula (4), but it is a divalent group represented by the general formula (5). An aromatic group may be sufficient and it may have both in 1 molecule or in several molecules.

  Although the manufacturing method of the siloxane modified polyimide resin used for this invention is not specifically limited, For example, it can synthesize | combine by reaction with aromatic tetracarboxylic acids, such as aromatic tetracarboxylic dianhydride, and diamine.

The Ar ₁ and Ar ₂ are tetravalent groups represented by the general formula (3). However, the polyimide resin is usually a reaction between an aromatic tetracarboxylic acid such as an aromatic tetracarboxylic dianhydride and a diamine. Therefore, Ar ₁ and Ar ₂ can be said to be residues of aromatic tetracarboxylic acids. In the general formula (1), the divalent aromatic group represented by Ar ₃ can be referred to as a diamine residue. Furthermore, the divalent group containing a siloxane structure in which R ₃ is formed at the position represented by the general formula (2) can be referred to as a diamine residue.

As the aromatic tetracarboxylic acids, aromatic tetracarboxylic acids in which Ar ₁ or Ar ₂ is formed by synthesis can be used. Examples of such aromatic tetracarboxylic acids include 2,2 ′, 3,3′-, 2,3,3 ′, 4′- or 3,3 ′, 4,4′-benzophenonetetracarboxylic acid dicarboxylic acid. Anhydride, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, 2,3 ′, 3,4′-biphenyltetracarboxylic dianhydride, 2,2 ′, 3,3′-biphenyl Tetracarboxylic dianhydride, 3,3 ′, 4,4′-diphenylsulfone tetracarboxylic dianhydride, 3,3 ′, 4,4′-diphenyl ether tetracarboxylic dianhydride, 2,3 ′, 3 , 4′-diphenyl ether tetracarboxylic dianhydride, bis (2,3-dicarboxyphenyl) ether dianhydride, 3,3 ″, 4,4 ″-, 2,3,3 ″, 4 ′ '-Or 2,2 ″, 3,3 ″ -p-terphenyltetracarboxylic dianhydride, 2,2-bis ( , 3- or 3,4-dicarboxyphenyl) -propane dianhydride, bis (2,3- or 3.4-dicarboxyphenyl) methane dianhydride, bis (2,3- or 3,4-di-) Carboxyphenyl) sulfone dianhydride, 1,1-bis (2,3- or 3,4-dicarboxyphenyl) ethane dianhydride.

In the present invention, together with the aromatic tetracarboxylic acids Ar ₁ or Ar ₂ is formed by combining, it is also possible to use other tetracarboxylic acids. When other tetracarboxylic acids are used, the amount used is preferably 50 mol% or less, more preferably 20 mol% or less, based on the aromatic tetracarboxylic acid used.

  Examples of such other tetracarboxylic acids include pyromellitic dianhydride, 2,3,5,6-cyclohexane dianhydride, 2,3,6,7-naphthalenetetracarboxylic dianhydride, 1 , 2,5,6-naphthalenetetracarboxylic dianhydride, 1,4,5,8-naphthalenetetracarboxylic dianhydride, 4,8-dimethyl-1,2,3,5,6,7-hexa Hydronaphthalene-1,2,5,6-tetracarboxylic dianhydride, 2,6- or 2,7-dichloronaphthalene-1,4,5,8-tetracarboxylic dianhydride, 2,3,6 , 7- (or 1,4,5,8-) tetrachloronaphthalene-1,4,5,8- (or 2,3,6,7-) tetracarboxylic dianhydride, 2,3,8, 9-, 3, 4, 9, 10-, 4, 5, 10, 11- or 5, 6, 11, 2-perylene-tetracarboxylic dianhydride, cyclopentane-1,2,3,4-tetracarboxylic dianhydride, pyrazine-2,3,5,6-tetracarboxylic dianhydride, pyrrolidine-2, 3,4,5-tetracarboxylic dianhydride, thiophene-2,3,4,5-tetracarboxylic dianhydride, 4,4-bis (2,3-dicarboxyphenoxy) diphenylmethane dianhydride, 1 , 2,7,8-, 1,2,6,7- or 1,2,9,10-phenanthrene-tetracarboxylic dianhydride, 2,3,6,7-anthracene tetracarboxylic dianhydride Can be mentioned.

As the diamine, a diamine in which Ar ₃ represented by the general formula (5) or the general formula (4) is formed by synthesis, and R ₃ is formed at a position represented by the general formula (2) by synthesis. A diamine containing a siloxane structure can be used.

Examples of the diamine that forms Ar ₃ represented by the general formula (5) by synthesis include 2,2-bis- [4- (4-aminophenoxy) phenyl] propane, 2,2-bis- [ 4- (3-aminophenoxy) phenyl] propane, bis [4- (4-aminophenoxy) phenyl] sulfone, bis [4- (3-aminophenoxy) phenyl] sulfone, bis [4- (4-aminophenoxy) ] Biphenyl, bis [4- (3-aminophenoxy) biphenyl, bis [1- (4-aminophenoxy)] biphenyl, bis [1- (3-aminophenoxy)] biphenyl, bis [4- (4-aminophenoxy) ) Phenyl] methane, bis [4- (3-aminophenoxy) phenyl] methane, bis [4- (4-aminophenoxy) phenyl] ether, [4- (3-aminophenoxy) phenyl] ether, bis [4- (4-aminophenoxy)] benzophenone, bis [4- (3-aminophenoxy)] benzophenone, bis [4,4 ′-(4- Aminophenoxy)] benzanilide, bis [4,4 ′-(3-aminophenoxy)] benzanilide, 9,9-bis [4- (4-aminophenoxy) phenyl] fluorene, 9,9-bis [4- (3 -Aminophenoxy) phenyl] fluorene.

Examples of the diamine formed by the synthesis of Ar ₃ represented by the general formula (4) include 4,4′-methylenedi-o-toluidine, 4,4′-methylenedi-2,6-xylidine, 4'-methylene-2,6-diethylaniline, 4,4'-diaminodiphenylpropane, 3,3'-diaminodiphenylpropane, 4,4'-diaminodiphenylethane, 3,3'-diaminodiphenylethane, 4, 4'-diaminodiphenylmethane, 3,3'-diaminodiphenylmethane, 4,4'-diaminodiphenyl sulfide, 3,3'-diaminodiphenyl sulfide, 4,4'-diaminodiphenylsulfone, 3,3'-diaminodiphenylsulfone, 4,4′-diaminodiphenyl ether, 3,3-diaminodiphenyl ether, 3,4′-diaminodiphenyl ether Ether, benzidine, 3,3′-diaminobiphenyl, 3,3′-dimethyl-4,4′-diaminobiphenyl, 3,3′-dimethoxybenzidine, 4,4 ″ -diamino-p-terphenyl, 3, 3 ″ -diamino-p-terphenyl, 2,2′-divinyl-4,4′-diamino-biphenyl, 9,9-bis (4-aminophenoxy) -9H-fluorene. Among these, it is preferable to use 2,2′-divinyl-4,4′-diaminobiphenyl (DVDABP), 9,9-bis (4-aminophenoxy) -9H-fluorene (BAFL).

Examples of the diamine containing a siloxane structure in which R ₃ is formed at the position represented by the general formula (2) by synthesis include ω, ω′-bis (2-aminoethyl) polydimethylsiloxane, ω, ω ′. -Bis (3-aminopropyl) polydimethylsiloxane, ω, ω'-bis (4-aminophenyl) polydimethylsiloxane, ω, ω'-bis (3-aminopropyl) polydiphenylsiloxane, ω, ω'-bis (3-aminopropyl) polymethylphenylsiloxane is mentioned. Such diamines are commercially available, and examples thereof include trade name F-8010 (manufactured by Shin-Etsu Chemical Co., Ltd.).

  In the present invention, other aromatic diamines can be used together with the diamine. When using other aromatic diamines, the amount used is preferably 50 mol% or less, more preferably 20 mol% or less, based on the diamine used.

  Examples of such other aromatic diamines include m-phenylenediamine, p-phenylenediamine, 2,6-diaminopyridine, 1,4-bis (4-aminophenoxy) benzene, and 1,3-bis (4 -Aminophenoxy) benzene, 4,4 '-[1,4-phenylenebis (1-methylethylidene)] bisaniline, 4,4'-[1,3-phenylenebis (1-methylethylidene)] bisaniline, bis ( p-aminocyclohexyl) methane, bis (p-β-amino-t-butylphenyl) ether, bis (p-β-methyl-δ-aminopentyl) benzene, p-bis (2-methyl-4-aminopentyl) Benzene, p-bis (1,1-dimethyl-5-aminopentyl) benzene, 1,5-diaminonaphthalene, 2,6-diaminonaphthalene, , 4-bis (β-amino-t-butyl) toluene, 2,4-diaminotoluene, m-xylene-2,5-diamine, p-xylene-2,5-diamine, m-xylylenediamine, p- Examples include xylylenediamine, 2,6-diaminopyridine, 2,5-diaminopyridine, 2,5-diamino-1,3,4-oxadiazole, and piperazine.

  The siloxane-modified polyimide resin used in the present invention has the repeating units represented by the general formulas (1) and (2), but the repeating unit represented by the general formula (1) is based on all repeating units. The molar ratio q is preferably from 0.01 to 0.95, and more preferably from 0.1 to 0.6. Further, the molar ratio p of the repeating unit represented by the general formula (2) to all repeating units is preferably 0.05 to 0.99, and more preferably 0.4 to 0.9. Such a molar ratio of repeating units is a case where the siloxane-modified polyimide resin is composed of only the repeating units represented by the general formulas (1) and (2) but has other repeating units. Is preferably within the above range. In addition, when it has another repeating unit, it is preferable that the value of p + q is 0.5 or more, and it is more preferable that it is 0.8 or more. Moreover, it is preferable that the value of p / (p + q) is in the range of 0.4 to 0.9.

  In the siloxane-modified polyimide resin used in the present invention, the elastic modulus of the molded product is preferably in the range of 0.2 to 3.0 GPa, more preferably in the range of 0.3 to 3.0 GPa. . Moreover, it is preferable that the glass transition point (Tg) of the molded product is 80 degreeC or more, and it is more preferable that it exists in the range of 100-300 degreeC.

  Further, the siloxane-modified polyimide resin used in the present invention is subjected to dehydration and ring closure by subjecting a precursor to be a siloxane-modified polyimide resin having the repeating units represented by the general formulas (1) and (2) to heat treatment or dehydration treatment. It is preferable that it is obtained by reacting. Examples of such a precursor include siloxane-modified polyamic acid resins having repeating units represented by the following general formulas (6) and (7).

In the general formulas (6) and (7), Ar ₁ , Ar ₂ , Ar ₃ , R ₃ , R ₄ , p and q are the same as Ar ₁ , Ar ₂ , Ar in the general formulas (1) and (2). ₃ , R ₃ , R ₄ , p and q have the same meaning. In the general formulas (6) and (7), R _{1 in} Ar ₃ in the general formula (6) or the general formula (7) from the viewpoint of imparting photopolymerizability to the siloxane-modified polyamic acid resin. It is preferable that a part of R ₄ is an alkenyl group. Examples of the alkenyl group include a group represented by CH ₂ ═CH—R ₆ —. R ₆ represents a single bond, an alkylene group having 1 to 6 carbon atoms, or a phenylene group, and is more preferably a single bond from the viewpoint of reactivity.

  Although the monomer which has an unsaturated bond used for the said cladding material is not specifically limited, From a reactive viewpoint, it is preferable that it is an acrylate monomer. Such acrylate monomers include, for example, 2-ethylhexyl acrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 2-hydroxyethyl acryloyl phosphate, 2-methoxyethoxyethyl acrylate, 2-ethoxyethoxyethyl acrylate, tetrahydrofluoro Freel acrylate, phenoxyethyl acrylate, isodecyl acrylate, stearyl acrylate, lauryl acrylate, glycidyl acrylate, allyl acrylate, ethoxy acrylate, methoxy acrylate, N, N′-dimethylaminoethyl acrylate, benzyl acrylate, 2-hydroxyethyl acryloyl phosphate, Dicyclopentadienyl acrylate, dicyclopentadiene Monoacrylates such as diethoxypentyl acrylate; dicyclopentenyl acrylate, dicyclopentenyloxyethyl acrylate, 1,3-butanediol diacrylate, 1,4-butanediol diacrylate, 1,6-butanediol diacrylate, diethylene glycol diacrylate , Neopentyl glycol diacrylate, polyethylene glycol 200 diacrylate, polyethylene glycol 400 diacrylate, polyethylene glycol 600 diacrylate, diethylene glycol diacrylate, neopentyl glycol diacrylate, hydroxypivalate ester neopentyl glycol diacrylate, triethylene glycol diacrylate Bis (acryloxyethoxy) bisphenol A, bi (Acryloxyethoxy) tetrabromobisphenol A, tripropylene glycol diacrylate, trimethylolpropane triacrylate, pentaerythritol triacrylate, tris (2-hydroxyethyl) isocyanate, pentaerythritol tetraacrylate, dipentaerythritol hexaacrylate, dipentaerythritol Polyfunctional acrylates such as monohydroxypentaacrylate are listed. These acrylate monomers can be used alone or in combination of two or more.

  The content of the monomer having an unsaturated bond used in the cladding material is preferably an amount in the range of 1 to 55 parts by mass with respect to 100 parts by mass of the siloxane-modified polyimide resin or its precursor. The amount is more preferably in the range of 50 parts by mass. If the content is less than the lower limit, the photosensitivity of the clad layer tends to be difficult to form an optical waveguide pattern. On the other hand, if the content exceeds the upper limit, shrinkage due to photocuring increases. Film curl tends to increase.

  Examples of the photopolymerization initiator used for the cladding material include acetophenone, 2,2-dimethoxyacetophenone, p-dimethylaminoacetophenone, Michler's ketone, benzyl, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin n- Propyl ether, benzoin isopropyl ether, benzoin n-butyl ether, benzyl dimethyl ketal, thioxazone, 2-chlorothioxazone, 2-methylthioxazone, 2-hydroxy-2-methyl-1-phenyl-1-one, 1- ( 4-Isopropylphenyl) -2-hydroxy-2-methylpropan-1-one, methylbenzoyl formate, 1-hydroxycyclohexyl phenyl ketone, 1,2-octane 1- [4- (phenylthio) -2- (o-benzoyloxime)] (“IRGACURE OXE-01” manufactured by Ciba Japan), ethanone-1- [9-ethyl-6- (2-methyl) Benzoyl) -9H-carbazol-3-yl] -1- [o-acetyloxime] (“IRGACURE OXE-02” manufactured by Ciba Japan). These photoinitiators can be used individually by 1 type or in combination of 2 or more types. The content of the photopolymerization initiator in the clad material used in the present invention is preferably an amount in the range of 1 to 20 parts by mass with respect to 100 parts by mass of the siloxane-modified polyimide resin or its precursor. The amount is more preferably in the range of 10 parts by mass. If the content is less than the lower limit, the photosensitivity of the cladding layer tends to be insufficient, so that it is difficult to form an optical waveguide pattern. On the other hand, if the content exceeds the upper limit, the light transmittance of the cladding layer is deteriorated. Therefore, it is difficult for light to reach the bottom of the cladding layer, and the photocuring of the bottom tends to be insufficient.

  The clad material used in the present invention may contain a sensitizer in addition to the siloxane-modified polyimide resin or precursor thereof, the monomer having an unsaturated bond, and the photopolymerization initiator. Examples of such a sensitizer include various aromatic compounds such as benzophenone. Moreover, when using such a sensitizer, the content shall be the quantity used as the range of 0.01-2 mass parts with respect to 100 mass parts of siloxane modified polyimide resins or its precursor. Is preferable, and it is more preferable that it is the quantity used as the range of 0.05-0.5 mass part.

  The clad material used in the present invention may contain another resin such as an epoxy resin, if necessary. The epoxy resin is not particularly limited as long as it has a plurality of epoxy groups in one molecule, and a commercially available liquid epoxy resin or solid epoxy resin can be appropriately used. Examples of the epoxy resin include alicyclic epoxy resins, bisphenol A type epoxy resins, bisphenol F type epoxy resins, bisphenol S type epoxy resins, biphenyl type epoxy resins having a biphenyl skeleton, naphthalene ring-containing epoxy resins, and dicyclopentadiene. Examples thereof include a dicyclopentadiene type epoxy resin having a skeleton, a phenol novolac type epoxy resin, a cresol novolac type epoxy resin, a triphenylmethane type epoxy resin, a bromine-containing epoxy resin, an aliphatic epoxy resin, and triglycidyl isocyanurate. These epoxy resins can be used individually by 1 type or in combination of 2 or more types. When such an epoxy resin is used, its content is preferably 40 parts by mass or less with respect to 100 parts by mass of the siloxane-modified polyimide resin or its precursor, and 20 parts by mass. It is more preferable that the amount is as follows.

  The clad material used in the present invention may contain an inorganic filler such as silica as long as it does not impair the light transmission capability.

  The core material used in the present invention is soluble in a developer used for forming an optical waveguide pattern. And it is preferable that the said core material contains a siloxane modified polyimide resin or its precursor. As the siloxane-modified polyimide resin or precursor thereof used for the core material, the same siloxane-modified polyimide resin or precursor thereof used for the cladding material can be used. On the other hand, in the present invention, since the core material does not require photosensitivity, the core material preferably does not substantially contain a photopolymerization initiator. Note that the core material does not substantially contain a photopolymerization initiator means that no photopolymerization initiator is added to the core material, and may be contained as an impurity, but the content thereof is siloxane-modified. It is 0.01 mass part or less with respect to 100 mass parts of polyimide resins or its precursor.

  The core material used in the present invention may contain a monomer having an unsaturated bond. As the monomer having such an unsaturated bond, the same monomer as the monomer having an unsaturated bond used for the cladding material can be used. Moreover, when using the monomer which has such an unsaturated bond, the content is the quantity used as the range of 1-30 mass parts with respect to 100 mass parts of siloxane modified polyimide resin or its precursor. The amount is preferably in the range of 3 to 10 parts by mass. If the content is less than the lower limit, the time required to dissolve the core during development tends to be longer, while if it exceeds the upper limit, the optical transmission capability in the obtained optical waveguide tends to be insufficient.

  The core material used in the present invention may contain another resin such as an epoxy resin as necessary. As an epoxy resin, the thing similar to the epoxy resin used for the said clad material can be used. When such an epoxy resin is used, its content is preferably 40 parts by mass or less with respect to 100 parts by mass of the siloxane-modified polyimide resin or its precursor, and 20 parts by mass. It is more preferable that the amount is as follows.

  The core material used for this invention may contain the inorganic filler in the range which does not inhibit optical transmission capability as needed. As said inorganic filler, the thing similar to the inorganic filler used for the said cladding material can be used.

  The clad material and the core material may be used as a solution containing the clad material and the core material as a solid content. Thus, when using as a solution, a viscosity etc. can be adjusted with various organic solvents. Examples of such an organic solvent include triethylene glycol dimethyl ether (triglyme), diethylene glycol dimethyl ether (diglyme), dimethylacetamide, N-methylpyrrolidone, propylene glycol monomethyl ether acetate (pegmia), and ethyl lactate. These organic solvents can be used individually by 1 type or in combination of 2 or more types. Moreover, when using as a solution in this way, the usage-amount of the said organic solvent shall be the quantity used as the range which is the range of 10-400 mass parts with respect to 100 mass parts of solid content of the said cladding material or the said core material. preferable. In addition, in this specification, the solution of the resin composition which contains 10 mass parts or more of organic solvents and is liquid at normal temperature is called varnish. Moreover, when using the said clad material and the said core material as a varnish, you may add a thixotropic material, an antifoamer, etc. to the said varnish as needed.

  The clad material and the core material used in the optical waveguide manufacturing method of the present invention have been described above. Hereinafter, the optical waveguide manufacturing method of the present invention will be described with reference to the drawings. In the following description and drawings, the same or corresponding elements are denoted by the same reference numerals, and duplicate descriptions are omitted.

  In the first step, a core layer made of the core material is formed. FIG. 1 is a schematic diagram showing a state in which a lower clad and a core layer are formed on a substrate. As shown in FIG. 1, a lower clad 2 and a core layer 3 are formed on the surface of a substrate 1. As the board | substrate 1, resin films, such as metal plates, such as a copper clad laminated board, copper foil, and SUS foil; A polyimide film, a polyethylene terephthalate (PET) film, a polypropylene (OPP) film, can be used. Moreover, the lower clad 2 can be formed on the surface of the base material 1 using the material used for a well-known optical waveguide suitably. Moreover, as an optical waveguide material used for the lower clad 2, it is preferable to use the said clad material from a viewpoint of forming a flexible optical waveguide. As a method of forming the lower clad 2, it is possible to employ (i) a method of casting a raw material varnish and (ii) a method of laminating a film state. Further, the thickness of the lower clad 2 is usually 1 to 40 μm, and more preferably 10 to 25 μm. In the first step, the core material 3 is used to form the core layer 3 on the surface of the lower clad 2 as shown in FIG. As a method for forming the core layer 3, (i) a method of casting a raw material varnish and (ii) a method of laminating a film state can be employed. In the case of employing the method of casting the raw material varnish, it is preferable that the drying temperature is in the range of 80 to 140 ° C. and the drying time is in the range of 5 to 20 minutes. The thickness of the core layer 3 is preferably in the range of 10 to 80 μm, and more preferably in the range of 45 to 60 μm. If the thickness of the core layer 3 is less than the lower limit, the optical transmission capability of the obtained optical waveguide tends to be insufficient. On the other hand, if the thickness exceeds the upper limit, the core layer pattern tends to be difficult to form.

  In the second step, a clad layer made of the clad material is formed on the surface of the core layer. FIG. 2 is a schematic view showing a state in which a cladding layer is formed on the core layer shown in FIG. As shown in FIG. 2, in the second step, the clad layer 4 is formed on the surface of the core layer 3 using the clad material. As a method for forming the clad layer 4, (i) a method of casting a raw material varnish, (ii) a method of laminating a film state can be employed. In the case of employing the method of casting the raw material varnish, it is preferable that the drying temperature is in the range of 80 to 140 ° C. and the drying time is in the range of 5 to 20 minutes. The thickness of the cladding layer 4 is preferably in the range of 1 to 40 μm, and more preferably in the range of 1 to 25 μm. If the thickness of the clad layer 4 is less than the lower limit, the resistance to the developer tends to be insufficient. On the other hand, if the thickness exceeds the upper limit, the pattern shape of the core tends to deteriorate.

In the third step, first, light is irradiated to a predetermined portion of the cladding layer. FIG. 3 is a schematic view showing a state in which ultraviolet rays are irradiated to predetermined portions of the cladding layer shown in FIG. As shown in FIG. 3, by irradiating a predetermined portion of the clad layer 4 with ultraviolet light using a photomask 5, the predetermined portion of the clad layer 4 is cured by light and is soluble in the developer. There is no clad 6 after photocuring. As a method of irradiating light as described above, a method of irradiating a predetermined portion with light using a photomask 5 as shown in FIG. 3 may be adopted, but a method of directly irradiating a predetermined portion with laser light is adopted. May be. Examples of light to be irradiated include ultraviolet rays and electron beams. Examples of the apparatus that irradiates ultraviolet rays or electron beams include a metal halide lamp, a high pressure mercury lamp, a low pressure mercury lamp, and a pulse type xenon lamp. Irradiation condition of the ultraviolet ray or electron beam may be suitably according to the type of lamp, but are not limited to, radiation exposure is usually in the range of 50~2000mJ / cm ^2.

  In the third step, next, a portion of the cladding layer not irradiated with light is removed by a developer to form a pattern of the cladding layer, and the patterned cladding layer is used as a resist mask. The pattern of the core layer is formed with a developer. FIG. 4 is a schematic diagram showing an optical waveguide in which a core and an upper clad formed on the core are formed. In the third step, the portion of the cladding layer 4 that is not irradiated with light is dissolved by the developer, while the portion that has become the clad 6 after photocuring by light irradiation is not dissolved by the developer. Then, the pattern of the cladding layer 4 is formed, and the upper cladding 11 is formed. Then, by patterning the upper clad 11 in this way, a part of the core layer 3 is exposed, and the exposed portion is dissolved in the developer, whereby the pattern of the core layer 3 is formed. It is formed. As the developer, it is necessary to use a developer capable of dissolving the core material and the clad material before light irradiation. Examples of the component of the developer include inorganic alkaline compounds such as sodium carbonate, sodium hydroxide, and potassium hydroxide; organic alkaline compounds such as triethylamine, monoethanolamine, and diethanolamine. These alkaline compounds can be used singly or in combination of two or more. The concentration of the alkaline compound in the developer is preferably in the range of 0.5 to 5% by mass. Among these developers, it is preferable to use a 1% by mass aqueous solution of sodium carbonate from the viewpoint of workability. The development conditions can be appropriately set according to the thickness of the clad layer or core layer, the type of developer, and the like. By forming the optical waveguide pattern in this manner, an optical waveguide in which the core 10 and the upper clad 11 formed on the core 10 are formed can be obtained. In addition, after forming the pattern of an optical waveguide, you may heat-process for 1 to 120 minutes, for example at the temperature of 120-220 degreeC.

  The method for producing an optical waveguide of the present invention is a method including the first step, the second step, and the third step. According to the method for manufacturing an optical waveguide of the present invention, as described above, the core layer pattern can be formed even when a non-photosensitive core material is used. Therefore, it becomes possible to reduce components that cause deterioration of the transparency of the core in the core material, and it becomes possible to manufacture an optical waveguide having a sufficient optical transmission capability.

  In the method for manufacturing an optical waveguide of the present invention, an overcladding may be formed so as to cover the optical waveguide on which the pattern is formed. As a method for forming such an overclad, a method similar to the method for forming the lower clad can be employed. Moreover, when forming an over clad, it is preferable to make the thickness into the range of 15-160 micrometers. Moreover, as a material for forming the over clad, it is preferable to use the clad material from the viewpoint of forming a flexible optical waveguide. Furthermore, in the optical waveguide obtained by the optical waveguide manufacturing method of the present invention, the refractive index of the core (core material) and the refractive indexes of the upper cladding, the lower cladding, and the overcladding (cladding material) are 1.45 to 1. It is preferable to be within the range of 65. Further, the absolute value of the difference between the refractive index of the core material and the refractive index of the cladding material is preferably 0.01 or more, and more preferably 0.02 or more.

EXAMPLES Hereinafter, although this invention is demonstrated more concretely based on an Example and a comparative example, this invention is not limited to a following example. In Examples and Comparative Examples, tetracarboxylic dianhydride, diamine, monomer having an unsaturated bond, photopolymerization initiator, and organic solvent were used as follows.
BPDA: 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride BTDA: 3,3 ′, 4,4′-benzophenone tetracarboxylic dianhydride ODPA: 3,3 ′, 4,4′- Diphenyl ether tetracarboxylic dianhydride BAFL: 9,9-bis (4-aminophenoxy) -9H-fluorene DVDABP: 2,2′-divinyl-4,4′-diaminobiphenyl KF-8010: number average molecular weight of about 850 Polydimethylsiloxane diamine (manufactured by Shin-Etsu Chemical Co., Ltd., trade name “KF-8010”)
DMAc: dimethylacetamide NMP: N-methyl-2-pyrrolidone PET-30: mixture of pentaerythritol triacrylate and pentaerythritol tetraacrylate (product name “PET-30” manufactured by Nippon Kayaku Co., Ltd.)
OXE-01: Photopolymerization initiator (manufactured by Ciba Japan, trade name “IRGACURE OXE-01”)
OXE-02: Photopolymerization initiator (Ciba Japan, trade name “IRGACURE OXE-02”)
(Preparation Example 1)
In a reactor equipped with a nitrogen inlet, 49.8 g (0.06 mol) KF-8010, 6.99 g (0.02 mol) BAFL and 4.73 g (0.02 mol) DVDABP, 108 g NMP and It was dissolved in a mixed solution of 108 g of diglyme, and the reactor was ice-cooled. To this, 31.0 g (0.1 mol) of ODPA was added dropwise over 20 minutes under a nitrogen atmosphere. After completion of the dropping, the temperature in the reactor was returned to room temperature (25 ° C.) and stirred for 5 hours under a nitrogen atmosphere to obtain a siloxane-modified polyamic acid resin solution. The viscosity of the obtained siloxane-modified polyamic acid resin solution (solvent: mixed solvent (mass ratio) NMP / diglyme = 1/1, resin concentration: 30% by mass) at 25 ° C. was measured using an E-type viscometer. It was 2500 cPa · s. Furthermore, 10 parts by mass of PET-30 was added to 100 parts by mass of the resulting siloxane-modified polyamic acid resin solution to obtain a core material (A-1).

(Preparation Example 2)
A core material (A-2) was obtained in the same manner as in Preparation Example 1 except that 45 parts by mass of PET-30 and 5 parts by mass of OXE-01 were added to 100 parts by mass of the siloxane-modified polyamic acid resin solution. .

(Preparation Example 3)
A core material (A-3) was obtained in the same manner as in Preparation Example 1 except that 10 parts by mass of PET-30 and 5 parts by mass of OXE-01 were added to 100 parts by mass of the siloxane-modified polyamic acid resin solution. .

(Preparation Example 4)
In a reactor equipped with a nitrogen injection tube, 68.0 g (0.08 mol) of KF-8010 and 4.73 g (0.02 mol) of DVDABP were dissolved in a mixed solution of 168 g of NMP and 72 g of diglyme and reacted. The vessel was ice-cooled. To this, 25.8 g (0.02 mol) of BPDA and 5.88 g (0.08 mol) of BTDA were added dropwise over 20 minutes under a nitrogen atmosphere. After completion of the dropping, the temperature in the reactor was returned to room temperature (25 ° C.) and stirred for 5 hours under a nitrogen atmosphere to obtain a siloxane-modified polyamic acid resin solution. The viscosity at 25 ° C. of the obtained siloxane-modified polyamic acid resin solution (solvent: mixed solvent (mass ratio: NMP / diglyme = 7/3), resin concentration: 30% by mass) was measured using an E-type viscometer. However, it was 4000 cPa · s. Further, 45 parts by mass of PET-30 and 5 parts by mass of OXE-02 were added to 100 parts by mass of the obtained siloxane-modified polyamic acid resin solution to obtain a clad material (B-1).

(Production Example 1)
After applying the core material (A-1) obtained in Preparation Example 1 on the surface of the PET substrate with a bar coater and drying at a temperature of 100 ° C. for 10 minutes, an exposure machine (manufactured by Hitech Corporation, lamp: high pressure mercury lamp) The film was irradiated with ultraviolet rays of 1000 mJ / cm ² and cured by heat treatment at 180 ° C. for 1 hour, and then peeled from the PET substrate to produce a film having a thickness of 20 μm. It was 1.545 when the refractive index in wavelength 850nm of the obtained film was measured using the refractive index measuring apparatus (The product made by Metricon company, brand name "model 2010 prism coupler"). In addition, the obtained film was subjected to dynamic viscoelasticity measurement using a tensile tester (manufactured by Shimadzu Corporation, trade name “Autograg AG-500A”), and the elastic modulus and Tg of the obtained film were measured. The elastic modulus was 0.35 GPa and Tg was 105 ° C.

(Production Example 2)
A film having a thickness of 20 μm was produced in the same manner as in Production Example 1 except that the core material (A-2) was used instead of the core material (A-1). When the refractive index, elastic modulus, and Tg at a wavelength of 850 nm of the obtained film were measured by the same method as in Production Example 1, the refractive index was 1.545, the elastic modulus was 0.50 GPa, and Tg was 115 ° C. Met.

(Production Example 3)
A film having a thickness of 20 μm was produced in the same manner as in Production Example 1 except that the core material (A-3) was used instead of the core material (A-1). When the refractive index, elastic modulus, and Tg of the obtained film at a wavelength of 850 nm were measured by the same method as in Production Example 1, the refractive index was 1.545, the elastic modulus was 0.35 GPa, and Tg was 105 ° C. Met.

(Production Example 4)
The clad material (B-1) obtained in Preparation Example 4 was coated on the surface of the PET substrate with a bar coater, dried at a temperature of 100 ° C. for 10 minutes, and then cured by a heat treatment at a temperature of 180 ° C. for 1 hour. Then, the film was peeled from the PET substrate to produce a film having a thickness of 20 μm. When the refractive index, elastic modulus, and Tg of the obtained film at a wavelength of 850 nm were measured by the same method as in Production Example 1, the refractive index was 1.520, the elastic modulus was 0.30 GPa, and Tg was 130 ° C. Met.

Example 1
The clad material (B-1) was applied on the surface of the PET substrate with a bar coater so that the thickness after drying was 20 μm, dried at a temperature of 100 ° C. for 10 minutes, and then at a temperature of 180 ° C. for 1 hour. A substrate with a lower clad in which a lower clad having a thickness of 20 μm was formed on a PET substrate was obtained by curing by heat treatment.

  Next, the core material (A-1) was applied on the surface of another PET substrate with a bar coater so that the thickness after drying was 50 μm, and dried at a temperature of 100 ° C. for 10 minutes to form a film. Later, the core material (A-1) film was peeled off from the PET substrate, and the film was laminated on the surface of the lower clad of the lower clad substrate with a vacuum laminator to obtain a substrate with a core layer. Thereafter, the clad material (B-1) was applied onto the surface of another PET substrate with a bar coater so that the thickness after drying was 20 μm, and dried at a temperature of 100 ° C. for 10 minutes to form a film. The clad material (B-1) film was peeled from the PET substrate, and the film was laminated on the surface of the core layer of the substrate with the core layer by a vacuum laminator to obtain a laminate (an optical waveguide before pattern formation). .

Then, the obtained laminate is irradiated with ultraviolet rays of 600 mJ / cm ² through a photomask on which a predetermined mask pattern is formed, using an exposure machine (manufactured by Hitec Corporation, lamp: high pressure mercury lamp), Thereafter, the unexposed part is removed by developing for 150 to 200 seconds at a temperature of 30 ° C. using a 1% by mass aqueous sodium carbonate solution, and further cured by a heat treatment at a temperature of 180 ° C. for 1 hour, A patterned optical waveguide was obtained. The thickness and width of the core in the obtained optical waveguide were 50 μm, respectively, and the patternability was good. The core material and the clad material are siloxane-modified polyimide resin precursors (polyamic acid). However, the core and the clad on the core are patterned and heat-cured after forming the wiring to form a siloxane-modified polyimide resin. .

  Next, the clad material (B-1) was applied onto the surface of another PET substrate with a bar coater so that the thickness after drying was 70 μm, and dried at a temperature of 100 ° C. for 10 minutes to form a film. Then, the clad material (B-1) film was peeled from the PET substrate, and the film was laminated on the surface of the patterned optical waveguide with a vacuum laminator to obtain an optical waveguide with an overclad. Moreover, when the optical transmission loss in the obtained optical waveguide with an overclad was measured, the optical transmission loss was 0.20 dB / cm, and it was confirmed that the optical waveguide had sufficient optical transmission capability.

The optical transmission loss was measured by the method based on the cut-back method described in “Optical Fiber Loss Test Method” of JIS C 6823 as follows. That is, a VCSEL having a wavelength of 850 nm and an illuminance of 1 mW / cm ² was used as a light source, and was incident on an optical waveguide with a GI fiber having a diameter of 50 μm through a mode scrambler, and emitted light was received using a PCS fiber having a diameter of 200 μm. The detection was performed using an infrared photodiode.

(Comparative Example 1)
The clad material (B-1) was applied on the surface of the PET substrate with a bar coater so that the thickness after drying was 20 μm, dried at a temperature of 100 ° C. for 10 minutes, and then at a temperature of 180 ° C. for 1 hour. A substrate with a lower clad in which a lower clad having a thickness of 20 μm was formed on a PET substrate was obtained by curing by heat treatment.

  Next, the core material (A-2) was applied onto the surface of another PET substrate with a bar coater so that the thickness after drying was 50 μm, and dried at a temperature of 100 ° C. for 10 minutes to form a film. Later, the core material (A-2) film was peeled from the PET substrate, and the film was laminated on the surface of the lower clad of the lower clad substrate with a vacuum laminator to obtain a substrate with a core layer.

Then, the obtained substrate with a core layer is irradiated with 1000 mJ / cm ² of ultraviolet rays using an exposure machine (manufactured by Hitec Corporation, lamp: high-pressure mercury lamp) through a photomask in which a predetermined mask pattern is formed. Thereafter, the unexposed portion is removed by developing for 150 to 200 seconds at a temperature of 30 ° C. using a 1% by mass aqueous sodium carbonate solution, and further cured by heat treatment at a temperature of 180 ° C. for 1 hour. Thus, a patterned optical waveguide was obtained. The thickness and width of the core in the obtained optical waveguide were 50 μm, respectively, and the patternability was good.

  Next, the clad material (B-1) was applied onto the surface of another PET substrate with a bar coater so that the thickness after drying was 70 μm, and dried at a temperature of 100 ° C. for 10 minutes to form a film. Then, the clad material (B-1) film was peeled from the PET substrate, and the film was laminated on the surface of the patterned optical waveguide with a vacuum laminator to obtain an optical waveguide with an overclad. Further, when the optical transmission loss in the obtained optical waveguide with overclad was measured by the same method as in Example 1, the optical transmission loss was 1.00 dB / cm, and the optical transmission capability was insufficient. .

(Comparative Example 2)
The clad material (B-1) was applied on the surface of the PET substrate with a bar coater so that the thickness after drying was 20 μm, dried at a temperature of 100 ° C. for 10 minutes, and then at a temperature of 180 ° C. for 1 hour. A substrate with a lower clad in which a lower clad having a thickness of 20 μm was formed on a PET substrate was obtained by curing by heat treatment.

  Next, the core material (A-3) was applied onto the surface of another PET substrate with a bar coater so that the thickness after drying was 50 μm, and dried at a temperature of 100 ° C. for 10 minutes to form a film. Later, the core material (A-3) film was peeled off from the PET substrate, and the film was laminated on the surface of the lower clad of the lower clad substrate with a vacuum laminator to obtain a substrate with a core layer.

Then, the obtained substrate with a core layer is irradiated with 1000 mJ / cm ² of ultraviolet rays using an exposure machine (manufactured by Hitec Corporation, lamp: high-pressure mercury lamp) through a photomask in which a predetermined mask pattern is formed. Thereafter, the unexposed portion is removed by developing for 150 to 200 seconds at a temperature of 30 ° C. using a 1% by mass aqueous sodium carbonate solution, and further cured by heat treatment at a temperature of 180 ° C. for 1 hour. Thus, a patterned optical waveguide was obtained. The thickness and width of the core in the obtained optical waveguide were 50 μm, respectively. However, defects such as peeling and dissolution of the core occurred frequently, and the patternability was poor.

  Next, the clad material (B-1) was applied onto the surface of another PET substrate with a bar coater so that the thickness after drying was 70 μm, and dried at a temperature of 100 ° C. for 10 minutes to form a film. Then, the clad material (B-1) film was peeled from the PET substrate, and the film was laminated on the surface of the patterned optical waveguide with a vacuum laminator to obtain an optical waveguide with an overclad. Further, when the optical transmission loss in the obtained optical waveguide with overclad was measured by the same method as in Example 1, the optical transmission loss was 0.20 dB / cm.

  As described above, according to the present invention, it is possible to provide an optical waveguide manufacturing method capable of manufacturing an optical waveguide having a sufficient optical transmission capability.

  DESCRIPTION OF SYMBOLS 1 ... Board | substrate, 2 ... Lower clad, 3 ... Core layer, 4 ... Cladding layer, 5 ... Photomask, 6 ... Clad after photocuring, 10 ... Core, 11 ... Upper clad.

Claims (7)

A method for producing an optical waveguide, wherein a pattern of the optical waveguide is formed by photolithography in which a portion not irradiated with light is irradiated with light after irradiating a predetermined portion of the resin layer having photosensitivity,
Forming a core layer made of a core material having solubility in the developer;
Forming a clad layer made of a clad material having photosensitivity and solubility in the developer before light irradiation on the surface of the core layer;
After irradiating a predetermined portion of the clad layer with light, the portion not irradiated with the developer is removed to form a pattern of the clad layer, and the development is performed using the clad layer with the pattern formed as a resist mask. Forming a pattern of the core layer with a liquid to obtain an optical waveguide comprising a core and an upper clad formed on the core;
A method for manufacturing an optical waveguide, comprising:   The method for producing an optical waveguide according to claim 1, wherein the clad material contains a siloxane-modified polyimide resin or a precursor thereof, a monomer having an unsaturated bond, and a photopolymerization initiator.   3. The method for manufacturing an optical waveguide according to claim 1, wherein the core material contains a siloxane-modified polyimide resin or a precursor thereof.   The method for manufacturing an optical waveguide according to claim 3, wherein the core material does not substantially contain a photopolymerization initiator.   The core material further contains a monomer having an unsaturated bond, and the content of the monomer is in the range of 1 to 30 parts by mass with respect to 100 parts by mass of the siloxane-modified polyimide resin or its precursor. The method of manufacturing an optical waveguide according to claim 3 or 4,   The method for producing an optical waveguide according to claim 1, wherein the developer is an aqueous sodium carbonate solution.   The thickness of the said cladding layer is 1-40 micrometers, The manufacturing method of the optical waveguide as described in any one of Claims 1-6 characterized by the above-mentioned.

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