JP5458682B2 - Optical waveguide forming resin film, optical waveguide using the same, manufacturing method thereof, and photoelectric composite wiring board - Google Patents

Description

  The present invention relates to a resin film for forming an optical waveguide, an optical waveguide using the same, a manufacturing method thereof, and an optoelectric composite wiring board.

  In recent years, in high-speed and high-density signal transmission between electronic devices and between wiring boards, signal transmission interference and attenuation are barriers in conventional transmission using electric wiring, and the limits of high-speed and high-density have begun to appear. In order to overcome this problem, a technique for optically connecting electronic elements and wiring boards, so-called optical interconnection, has been studied. As an optical transmission line, polymer optical waveguides are attracting attention because of their ease of processing, low cost, high flexibility in wiring, and high density. In particular, the use of optical waveguides in mobile phones, notebook computers, and the like has been studied.

By the way, in an electronic device such as a mobile phone, when a flexible optical waveguide is used for signal transmission between two mechanisms that can be opened and closed, the flexible optical waveguide may straddle the connecting portion (hinge) of the two mechanisms. Conceivable. In this case, the flexible optical waveguide is bent 0 by the hinge, and there are cases where cracks or cracks occur due to the bending. In particular, because of recent demands for downsizing electronic devices, it is required that the hinge be bent with a small bending radius of about 1 to 2 mm. there were.
In particular, an opto-electric hybrid board that combines optical wiring and electrical wiring is desired in order to cope with space saving and thinning. However, the thickness of the opto-electric hybrid board is further increased. The bending durability was demanded.

  As a method for improving the bending durability of the flexible optical waveguide, for example, as described in Patent Document 1, there is a method of reducing the thickness of the core layer or the cladding layer of the bent portion. Patent Document 1 discloses a manufacturing method in which these optical waveguide layers are thinned using a liquid material. However, since the material is in a liquid state, it is difficult to control the film thickness and there is a problem in productivity. . Moreover, although the invention (for example, patent document 2) regarding the resin film for optical waveguide formation which is excellent in film thickness controllability is disclosed, since the film thickness is uniform in the whole film, the core layer or clad layer of a bending part It was difficult to reduce the thickness.

International Publication 2007/026601 Pamphlet International Publication 2006/038691 Pamphlet

  In view of the above problems, the present invention provides a resin film for forming an optical waveguide capable of arbitrarily controlling the thickness of a core layer or a clad layer of an optical waveguide, an optical waveguide using the same, a manufacturing method thereof, and an optoelectric composite wiring board The purpose is to provide.

As a result of intensive studies, the present inventors have found that the above problem can be solved by using a resin film for forming an optical waveguide having portions having different thicknesses in the same film.
That is, the present invention
(1) A resin film for forming an optical waveguide having portions having different thicknesses in the same film,
(2) The resin film for forming an optical waveguide according to (1) above, wherein a resin layer for forming an optical waveguide is formed on a base film,
(3) The resin film for forming an optical waveguide according to the above (1) or (2), wherein the intermediate part is thinner than at least one end part,
(4) The resin film for forming an optical waveguide according to the above (3), wherein the intermediate part is thinner than both end parts,
(5) The resin film for forming an optical waveguide according to any one of the above (1) to (4), wherein one end is thicker than the other end,
(6) The resin film for forming an optical waveguide according to any one of the above (1) to (5), wherein the film thickness changing portion has a tapered shape,
(7) The resin film for forming an optical waveguide according to any one of (1) to (6), wherein the portions having different thicknesses are provided in the resin layer for forming an optical waveguide,
(8) The optical waveguide forming resin film according to (7), wherein the optical waveguide forming resin layer is an upper clad layer forming resin layer,
(9) The optical waveguide forming resin film according to (7), wherein the optical waveguide forming resin layer is a core layer forming resin layer,
(10) An optical waveguide produced by using the resin film for forming an optical waveguide according to any one of (1) to (9) above,
(11) In the optical waveguide in which the lower clad layer, the core pattern, and the upper clad layer are sequentially laminated on the base material, the core pattern and / or the upper clad layer are any one of the above (1) to (8). The optical waveguide according to (10), which is prepared using a resin film for forming an optical waveguide,
(12) A photoelectric composite wiring board obtained by combining the optical waveguide according to (10) or (11) above with an electrical wiring board,
(13) A method for producing a resin film for forming an optical waveguide having portions having different thicknesses in the same film, wherein (I) a second is formed on at least one end of the first optical waveguide forming resin layer. A method for producing a resin film for forming an optical waveguide, comprising a step of forming a resin layer for forming an optical waveguide;
(14) The method for producing a resin film for forming an optical waveguide according to the above (13), wherein, in the step (I), the second optical waveguide forming resin layer is provided on both ends of the first optical waveguide forming resin layer. ,
(15) In the step (I), a masking film is applied to at least one end or a portion other than both ends of the second optical waveguide forming resin layer on the first optical waveguide forming resin layer. Forming a second optical waveguide forming resin layer on the entire surface of the first optical waveguide forming resin layer including both the portion where the masking film is disposed and the portion where the masking film is not disposed, By removing the second optical waveguide forming resin layer on the masking film together with the masking film, second at least one end or both ends on the first optical waveguide forming resin layer The method for producing a resin film for forming an optical waveguide according to the above (13) or (14), wherein the resin layer for forming an optical waveguide is formed,
(16) In the step (I), a second optical waveguide forming resin layer is used for forming the first optical waveguide on at least one end or both ends of the first optical waveguide forming resin layer. By laminating a film on which a second optical waveguide forming resin layer is formed on a supporting base so as to be in contact with the resin layer, and removing the supporting base, the first optical waveguide forming resin layer is removed. The method for producing a resin film for forming an optical waveguide according to the above (13) or (14), wherein a second optical waveguide forming resin layer is formed on at least one end or both ends of
(17) After the step (I), further, (II) surfaces of the first optical waveguide forming resin layer and the second optical waveguide forming resin layer so that the film thickness changing portion has a tapered shape. The method for producing a resin film for forming an optical waveguide according to any one of the above (13) to (16), comprising a step of smoothing the step of
(18) The method for producing a resin film for forming an optical waveguide according to (17), wherein the smoothing is performed using a flat plate type vacuum pressurizing laminator,
(19) The method for producing a resin film for forming an optical waveguide according to any one of (13) to (18), wherein the first resin layer for forming an optical waveguide is formed on a substrate.
(20) The method for producing a resin film for forming an optical waveguide according to (19), further including (III) a step of removing the substrate after the step (I),
(21) The method for producing a resin film for forming an optical waveguide according to the above (19) or (20), wherein the substrate is a substrate film,
(22) The resin film for forming an optical waveguide according to any one of (13) to (21), wherein the first resin layer for forming an optical waveguide and / or the second resin layer for forming an optical waveguide is a film. Production method,
(23) In the method of manufacturing an optical waveguide in which a lower clad layer, a core pattern, and an upper clad layer are sequentially laminated, the upper clad layer is the resin film for forming an optical waveguide according to any one of (1) to (7). A method of manufacturing an optical waveguide formed using the
(24) In an optical waveguide manufacturing method in which a lower cladding layer, a core pattern, and an upper cladding layer are sequentially stacked, the upper cladding layer is manufactured by the manufacturing method according to any one of (13) to (22) above. A method for producing an optical waveguide formed using a resin film for forming an optical waveguide;
Is to provide.

  ADVANTAGE OF THE INVENTION According to this invention, the resin film for optical waveguide formation which can control arbitrarily the film thickness of the core layer or clad layer of an optical waveguide, an optical waveguide using this, and an optoelectric composite wiring board can be provided.

It is a schematic diagram which shows the one aspect | mode of the resin film for optical waveguide formation of this invention. It is a schematic diagram which shows the one aspect | mode of the resin film for optical waveguide formation of this invention. It is a schematic diagram which shows the one aspect | mode of the resin film for optical waveguide formation of this invention. It is a schematic diagram which shows the one aspect | mode of the resin film for optical waveguide formation of this invention. It is a figure explaining the manufacturing method of the resin film for optical waveguide formation of this invention. It is a figure explaining the manufacturing method of the resin film for optical waveguide formation of this invention. It is a figure explaining the manufacturing method of the resin film for optical waveguide formation of this invention. It is a figure explaining the coating machine head used for manufacture of the resin film for optical waveguide formation of this invention. It is a figure explaining the manufacturing method of the flexible optical waveguide using the resin film for optical waveguide formation of this invention. It is a figure explaining the resin film for optical waveguide formation. It is a figure explaining the optical waveguide cross section after core patterning. It is a schematic diagram which shows one aspect | mode of the optical waveguide obtained by this invention. It is a conceptual diagram which shows the content of a bending durability test.

The resin film for forming an optical waveguide of the present invention has portions having different thicknesses in the same film. The resin film for forming an optical waveguide may be composed of the resin layer for forming an optical waveguide alone, but it is preferable that the portions having different thicknesses are provided on the resin layer for forming an optical waveguide. Examples of the optical waveguide forming resin layer include a clad layer forming resin layer and a core layer forming resin layer. As shown in FIG. 1, an optical waveguide forming resin layer 3 was formed on a base film 2. It is preferable to use one because it is easy to handle.
The shape of the optical waveguide forming resin layer may be changed depending on the purpose. For example, one end of the film is thicker than the other end (FIG. 2), and the step of the film thickness changing portion is tapered. And the like (FIG. 3). A cover film may be provided on the optical waveguide forming resin layer as necessary.

Although the manufacturing method of the resin film for optical waveguide formation of this invention will not be specifically limited if the said shape is achieved, For example, it is performed by the method shown in FIG. First, a first optical waveguide forming resin layer 11 is formed (see FIG. 5A), and a masking film 12 prepared in a desired width is provided on the optical waveguide forming resin layer 11 (see FIG. 5). 5 (b)). Next, a second optical waveguide forming resin layer similar to that shown in FIG. 5A is applied so as to cover the masking film 12 (see FIG. 5C and FIG. 5D), and then one side of the masking film 12 is covered. (See FIG. 5 (e) to remove the support substrate). Finally, the unnecessary portion is peeled off together with the masking film (see FIGS. 5 (f) and 5 (g)). Moreover, as shown in FIG.6 and FIG.7, the method of affixing the resin film for optical waveguide formation prepared separately in the part to make thick is also mentioned. Further, as shown in FIG. 7, a step 26 is applied to the method of overlying the optical waveguide forming resin layers 23 and 24 on the portion to be thickened, or to the shape of the coating machine head 25 used for film formation as shown in FIG. It can also be produced by devising a coating method such as a method of providing a coating.
The resin film for forming an optical waveguide produced by the method as described above is heated or pressurized, and further, these are used in combination to smooth the film thickness changing portion, whereby a form as shown in FIG. 3 can be obtained. In this case, since the change in the thickness of the optical waveguide layer is gently formed, for example, when used as a core film, reduction of optical loss can be expected, and when used as an upper cladding layer, reduction of bubbles when the core is embedded can be expected.
By using the film-like optical waveguide manufactured by the method as described above, the film thickness of the core layer or the cladding layer of the optical waveguide can be arbitrarily controlled.

Hereinafter, an optical waveguide manufacturing process using the optical waveguide forming resin film of the present invention for the core layer and the second cladding layer (upper cladding layer) will be described with reference to FIG. Since the optical waveguide produced here has a portion whose film thickness is thinner than the end portion, it is excellent in flexibility.

(I) Step (I) Step is a step of forming a first cladding layer. There are various methods for forming the first cladding layer. As shown in FIG. 9A, the cladding layer forming resin of the cladding layer forming resin film is cured to form the first cladding layer. A method of forming the (lower cladding layer) 52 is preferable.
As shown in FIG. 10, the clad layer forming resin film 61 used here is obtained by applying a clad layer forming resin 63 on a base film 62, and a protective film (separator) 64 is provided as necessary. It has a laminated structure.
In addition, the protective film is provided for the purpose of improving the winding property when manufacturing the clad layer forming resin film or in the form of a roll in the production of the clad layer forming resin film, The thing similar to what is illustrated as a base film mentioned later can be used. The protective film is preferably not subjected to an adhesive treatment such as a corona treatment in order to facilitate peeling from the clad layer forming resin film, and may be subjected to a release treatment or an antistatic treatment as necessary. .

  As the base film 62, the clad layer forming resin 63 is applied, and it becomes a supporting base material in the subsequent optical waveguide manufacturing process. There are no particular restrictions on the material, but flexibility and toughness. From the viewpoint of having polyester, such as polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polyethylene, polypropylene, polyamide, polycarbonate, polyphenylene ether, polyether sulfide, polyphenylene sulfide, polyarylate, liquid crystal polymer, polysulfone, polyethersulfone , Polyether ether ketone, polyether imide, polyamide imide, polyimide, aramid and the like.

Among these substrate films, in the production of optical waveguides, polyethylene terephthalate, polyethylene naphthalate, etc. from the viewpoint of heat resistance that can be produced, resistance to developer, ultraviolet transparency for curing the clad layer, and availability Polyester, polyamide, polyphenylene sulfide, and aramid are preferably used for the base film. In particular, aramid, polyamide film, polyethylene naphthalate film and polyphenylene sulfide film are used from the viewpoint of heat resistance and low shrinkage during the production of optical waveguides, and polyethylene is used from the viewpoint of ultraviolet transparency for curing the cladding layer. A terephthalate film is particularly preferred.
The surface of the base film may be treated in order to improve adhesion with the clad layer forming resin 63, for example, physical or chemical surface treatment such as oxidation method or unevenness method. Can be mentioned. Examples of the oxidation method include corona treatment, chromium oxidation treatment, flame treatment, hot air treatment, ozone / ultraviolet treatment method, and examples of the unevenness method include a sand blast method and a solvent treatment method.

  In the step (I), when the protective film 64 is provided on the opposite side of the base film of the clad layer forming resin film (see FIG. 10), the protective film is peeled off, and then the clad layer forming resin film is removed. The first clad layer (lower clad layer) 52 is formed by curing with light (ultraviolet light (UV) or the like) or heating.

The clad layer forming resin used in the present invention is not particularly limited as long as it is a resin composition that has a lower refractive index than the core layer and is cured by light or heat, and includes a thermosetting resin composition and a photosensitive resin composition. Can be used.
More preferably, the clad layer forming resin is composed of a resin composition containing (A) a base polymer, (B) a light or thermopolymerizable compound, and (C) a light or thermopolymerization initiator. preferable.

The (A) base polymer used here is for forming a clad layer and ensuring the strength of the clad layer, and is not particularly limited as long as the object can be achieved, phenoxy resin, epoxy resin, (Meth) acrylic resin, polycarbonate resin, polyarylate resin, polyether amide, polyether imide, polyether sulfone, etc., or derivatives thereof. These base polymers may be used alone or in combination of two or more.
Of the base polymers exemplified above, from the viewpoint of high heat resistance, the main chain preferably has an aromatic skeleton, and particularly preferably a phenoxy resin.
From the viewpoint of three-dimensional crosslinking and improving heat resistance, an epoxy resin, particularly an epoxy resin that is solid at room temperature is preferable. Furthermore, (B) compatibility with the light or thermopolymerizable compound, which will be described in detail later, is important for ensuring the transparency of the resin film for forming the clad layer. From this point, the above phenoxy resin and (meta ) Acrylic resin is preferred. Here, (meth) acrylic resin means acrylic resin and methacrylic resin.

  Among phenoxy resins, a phenoxy resin using at least one selected from bisphenol A, bisphenol A type epoxy compound, bisphenol F, bisphenol F type epoxy compound and derivatives thereof as a copolymerization component has heat resistance, adhesion and solubility. It is preferable because it is excellent. Preferred examples of the bisphenol A or bisphenol A type epoxy compound include tetrabromobisphenol A and tetrabromobisphenol A type epoxy compounds. Moreover, as a derivative of bisphenol F or a bisphenol F-type epoxy compound, tetrabromobisphenol F, a tetrabromobisphenol F-type epoxy compound, etc. are mentioned suitably. Specific examples of the bisphenol A / bisphenol F copolymer type phenoxy resin include “Phenotote YP-70” (trade name) manufactured by Toto Kasei Co., Ltd.

  Specific examples of the bisphenol A type epoxy resin include, for example, “Epototo YD-7020, Epototo YD-7019, Epototo YD-7007” (all trade names) manufactured by Toto Chemical Co., Ltd. “Epicoat 1010, Epicoat 1009, Epicoat 1008” (all trade names) manufactured by Japan Epoxy Resin Co., Ltd. and the like can be mentioned.

  (A) The molecular weight of the base polymer is preferably 5,000 or more in terms of number average molecular weight, more preferably 10,000 or more, and particularly preferably 30,000 or more, from the viewpoint of film formability. Although there is no restriction | limiting in particular about the upper limit of a number average molecular weight, From the viewpoint of (B) compatibility with light or a thermopolymerizable compound, light or thermosetting (exposure developability), it is 1,000,000 or less. It is preferable that it is 500,000 or less, particularly 200,000 or less. The number average molecular weight in the present invention is a value measured by gel permeation chromatography (GPC) and converted to standard polystyrene.

  (A) It is preferable that the compounding quantity of a base polymer shall be 10-80 mass% with respect to the total amount of (A) component and (B) component. When the blending amount is 10% by mass or more, there is an advantage that it is easy to form a thick film of about 50 to 500 μm necessary for forming an optical waveguide, while when it is 80% by mass or less, light or heat is obtained. The curing reaction proceeds sufficiently. From the above viewpoint, the blending amount of (A) the base polymer is more preferably 20 to 70% by mass.

  Next, (B) the light or thermopolymerizable compound is not particularly limited as long as it is polymerized by irradiation with light such as ultraviolet rays or heating, and a compound or molecule having two or more epoxy groups in the molecule. And compounds having an ethylenically unsaturated group.

  Specific examples of compounds having two or more epoxy groups in the molecule include bisphenol A type epoxy resins, tetrabromobisphenol A type epoxy resins, bisphenol F type epoxy resins, bisphenol AD type epoxy resins, naphthalene type epoxy resins, etc. Bifunctional aromatic glycidyl ether; phenol novolac type epoxy resin, cresol novolac type epoxy resin, dicyclopentadiene-phenol type epoxy resin, tetraphenylol ethane type epoxy resin, etc. polyfunctional aromatic glycidyl ether; polyethylene glycol type epoxy resin, Bifunctional aliphatic glycidyl ether such as polypropylene glycol type epoxy resin, neopentyl glycol type epoxy resin, hexanediol type epoxy resin; hydrogenated bisphenol A type epoxy Bifunctional alicyclic glycidyl ethers such as resins; polyfunctional aliphatic glycidyl ethers such as trimethylolpropane type epoxy resins, sorbitol type epoxy resins and glycerin type epoxy resins; bifunctional aromatic glycidyl esters such as phthalic acid diglycidyl esters; Bifunctional alicyclic glycidyl esters such as tetrahydrophthalic acid diglycidyl ester and hexahydrophthalic acid diglycidyl ester; bifunctional aromatic glycidyl amines such as N, N-diglycidylaniline and N, N-diglycidyltrifluoromethylaniline N, N, N ′, N′-tetraglycidyl-4,4-diaminodiphenylmethane, 1,3-bis (N, N-glycidylaminomethyl) cyclohexane, N, N, O-triglycidyl-p-aminophenol Polyfunctional aromatic glycidi such as Amines; bifunctional alicyclic epoxy resins such as alicyclic diepoxy acetals, alicyclic diepoxy adipates, alicyclic diepoxy carboxylates, vinylcyclohexene dioxide; bifunctional heterocyclic epoxy resins such as diglycidyl hydantoin A polyfunctional heterocyclic epoxy resin such as triglycidyl isocyanurate; a bifunctional or polyfunctional silicon-containing epoxy resin such as an organopolysiloxane type epoxy resin;

  These compounds having two or more epoxy groups in the molecule usually have a molecular weight of about 100 to 2,000, more preferably about 150 to 1,000, and those that are liquid at room temperature are suitably used. Moreover, these compounds can be used individually or in combination of 2 or more types, Furthermore, it can also be used in combination with another photo or thermopolymerizable compound. In addition, the molecular weight of the light or thermopolymerizable compound in the present invention can be measured by GPC method or mass spectrometry.

  Specific examples of the compound having an ethylenically unsaturated group in the molecule include (meth) acrylate, vinylidene halide, vinyl ether, vinyl pyridine, vinyl phenol, etc. Of these, transparency and heat resistance are included. From the viewpoint, (meth) acrylate is preferable, and any of monofunctional, bifunctional, trifunctional or higher can be used. Here, (meth) acrylate refers to acrylate or methacrylate. An acrylate means a compound having an acryloyl group, and a methacrylate means a compound having a methacryloyl group. Moreover, monofunctional here means having any one of an acryloyl group and a methacryloyl group.

  Monofunctional (meth) acrylates include methoxypolyethylene glycol (meth) acrylate, phenoxypolyethylene glycol (meth) acrylate, lauryl (meth) acrylate, isostearyl (meth) acrylate, and 2- (meth) acryloyloxyethyl succinic acid. , Paracumylphenoxyethylene glycol (meth) acrylate, 2-tetrahydropyranyl (meth) acrylate, isobornyl (meth) acrylate, methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, benzyl (meth) acrylate Etc.

  As the bifunctional (meth) acrylate, ethoxylated 2-methyl-1,3-propanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate, 1,6-hexanediol di (meth) Acrylate, 2-methyl-1,8-octanediol diacrylate, 1,9-nonanediol di (meth) acrylate, 1,10-nonanediol di (meth) acrylate, ethoxylated polypropylene glycol di (meth) acrylate, propoxy Ethoxylated bisphenol A diacrylate, ethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, polypropylene glycol Di (meth) acrylate, ethoxylated bisphenol A di (meth) acrylate, tricyclodecane di (meth) acrylate, ethoxylated cyclohexanedimethanol di (meth) acrylate, 2-hydroxy-1-acryloxy-3-methacryloxypropane, 2-hydroxy-1,3-dimethacryloxypropane, 9,9-bis [4- (2-acryloyloxyethoxy) phenyl] fluorene, 9,9-bis [3-phenyl-4-acryloylpolyoxyethoxy) fluorene Bisphenol A type, phenol novolak type, cresol novolak type, glycidyl ether type epoxy (meth) acrylate, and the like.

  Furthermore, as tri- or more functional (meth) acrylates, ethoxylated isocyanuric acid tri (meth) acrylate, ethoxylated glycerin tri (meth) acrylate, trimethylolpropane tri (meth) acrylate, ethoxylated trimethylolpropane tri (meth) Acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, ethoxylated pentaerythritol tetra (meth) acrylate, propoxylated pentaerythritol tetra (meth) acrylate, ditrimethylolpropane tetra (meth) acrylate, caprolactone modified ditri Examples include methylolpropane tetraacrylate and dipentaerythritol hexa (meth) acrylate. These can be used alone or in combination of two or more.

  Here, (meth) acrylate means acrylate and methacrylate. The blending amount of the (B) light or thermopolymerizable compound is preferably 20 to 90% by mass with respect to the total amount of the component (A) and the component (B). When the blending amount is 20% by mass or more, the base polymer can be easily entangled and cured, and when it is 90% by mass or less, a sufficiently thick clad layer can be easily formed. it can. From the above viewpoint, the blending amount of the (B) light or thermopolymerizable compound is more preferably 30 to 80% by mass.

  Next, the photo or thermal polymerization initiator of component (C) is not particularly limited. For example, as an initiator of an epoxy compound, an aryldiazonium salt such as p-methoxybenzenediazonium hexafluorophosphate; a diphenyliodonium hexafluorophosphonium salt; Diaryl iodonium salts such as diphenyliodonium hexafluoroantimonate salt; triphenylsulfonium hexafluorophosphonium salt, triphenylsulfonium hexafluoroantimonate salt, diphenyl-4-thiophenoxyphenylsulfonium hexafluoroantimonate salt, diphenyl-4-thiophenoxy Phenylsulfonium hexafluoroantimonate salt, diphenyl-4-thiophenoxyphenylsulfonium pentafluorohydroxyantimonate Triarylsulfonium salts such as salts; Triarylselenonium salts such as triphenylselenonium hexafluorophosphonium salt, triphenylselenonium borofluoride salt, triphenylselenonium hexafluoroantimonate salt; dimethylphenacylsulfonium hexafluoroantimonate Salts, dialkylphenazylsulfonium salts such as diethylphenacylsulfonium hexafluoroantimonate salt; dialkyl-4-hydroxyphenyl such as 4-hydroxyphenyldimethylsulfonium hexafluoroantimonate salt, 4-hydroxyphenylbenzylmethylsulfonium hexafluoroantimonate salt Sulfonium salt; α-hydroxymethylbenzoin sulfonate, N-hydroxyimide sulfonate, α-sulfo Rokishiketon, such as sulfonic acid esters, such as β- sulfo Niro carboxymethyl ketone.

  Moreover, the initiator of the compound which has an ethylenically unsaturated group in a molecule | numerator can also be used, for example, benzophenone, N, N'-tetramethyl-4,4'-diaminobenzophenone (Michler ketone), N, N'-tetraethyl- 4,4′-diaminobenzophenone, 4-methoxy-4′-dimethylaminobenzophenone, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butan-1-one, 2,2-dimethoxy- 1,2-diphenylethane-1-one, 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1- [4- (2-hydroxyethoxy) phenyl] -2 -Hydroxy-2-methyl-1-propan-1-one, 1,2-methyl-1- [4- (methylthio) pheny Aromatic ketones such as 2-morpholinopropan-1-one; 2-ethylanthraquinone, phenanthrenequinone, 2-tert-butylanthraquinone, octamethylanthraquinone, 1,2-benzanthraquinone, 2,3-benzanthraquinone, 2-phenylanthraquinone, 2,3-diphenylanthraquinone, 1-chloroanthraquinone, 2-methylanthraquinone, 1,4-naphthoquinone, 9,10-phenanthraquinone, 2-methyl 1,4-naphthoquinone, 2,3- Quinones such as dimethyl anthraquinone; benzoin ether compounds such as benzoin methyl ether, benzoin ethyl ether and benzoin phenyl ether; benzoin compounds such as benzoin, methyl benzoin and ethyl benzoin; Benzyl derivatives such as 2-aryl; 2- (o-chlorophenyl) -4,5-diphenylimidazole dimer, 2- (o-chlorophenyl) -4,5-di (methoxyphenyl) imidazole dimer, 2- ( o-fluorophenyl) -4,5-diphenylimidazole dimer, 2- (o-methoxyphenyl) -4,5-diphenylimidazole dimer, 2- (p-methoxyphenyl) -4,5-diphenylimidazole 2,4,5-triarylimidazole dimer such as dimer; bis (2,4,6-trimethylbenzoyl) phenylphosphine oxide, bis (2,6-dimethoxybenzoyl) -2,4,4- Phosphine oxides such as trimethylpentylphosphine oxide and 2,4,6-trimethylbenzoyldiphenylphosphine oxide Sides; acridine derivatives such as 9-phenylacridine and 1,7-bis (9,9'-acridinyl) heptane; N-phenylglycine, N-phenylglycine derivatives, coumarin compounds and the like. In the above 2,4,5-triarylimidazole dimer, the aryl group substituents of the two 2,4,5-triarylimidazoles may give the same and symmetrical compounds, or differently asymmetrical A compound may be provided. Moreover, you may combine a thioxanthone type compound and a tertiary amine compound like the combination of diethyl thioxanthone and dimethylaminobenzoic acid. Of these compounds, aromatic ketones and phosphine oxides are preferred from the viewpoint of improving the transparency of the core layer and the cladding layer. These (C) light or thermal polymerization initiators can be used alone or in combination of two or more.

  (C) It is preferable that the compounding quantity of light or a thermal-polymerization initiator shall be 0.1-10 mass parts with respect to 100 mass parts of total amounts of (A) component and (B) component. If it is 0.1 part by mass or more, sensitivity to light and heat is sufficient, while if it is 10 parts by mass or less, only the surface of the optical waveguide is selectively cured, and curing does not become insufficient. Further, it is preferable that the propagation loss does not increase due to absorption of light or the thermal polymerization initiator itself. From the above viewpoint, the blending amount of (C) light or the thermal polymerization initiator is more preferably 1 to 5 parts by mass.

  In addition to the above, the clad layer forming resin of the present invention contains an antioxidant, an anti-yellowing agent, an ultraviolet absorber, a visible light absorber, a colorant, a plasticizer, a stabilizer, and a filler as necessary. You may add what is called additives, such as an agent, in the ratio which does not have a bad influence on the effect of this invention.

  The resin film for forming a clad layer can be easily produced by dissolving a resin composition containing the components (A) to (C) in a solvent, applying the resin composition to the base film, and removing the solvent. The solvent used here is not particularly limited as long as it can dissolve the resin composition. For example, acetone, methyl ethyl ketone, methyl cellosolve, ethyl cellosolve, toluene, N, N-dimethylacetamide, propylene glycol monomethyl ether, A solvent such as propylene glycol monomethyl ether acetate, cyclohexanone, N-methyl-2-pyrrolidone, or a mixed solvent thereof can be used. The solid content concentration in the resin solution is preferably about 30 to 80% by mass.

  Regarding the thickness of the first cladding layer, the thickness after drying is preferably in the range of 5 to 500 μm. When the thickness is 5 μm or more, a clad thickness necessary for light confinement can be secured, and when the thickness is 500 μm or less, it is easy to control the film thickness uniformly. From the above viewpoint, the thickness of the cladding layer is preferably in the range of 10 μm to 100 μm.

  Further, the first clad layer (lower clad layer) formed first and the second clad layer (upper clad layer) for embedding a core pattern described later may be the same or different. However, in order to embed the core pattern, it is preferable that the thickness of the second cladding layer (upper cladding layer) is larger than the thickness of the core layer.

Step (II) Step (II) is a step of laminating a core layer-forming resin film having a thinner intermediate portion than the end portion on the first clad layer (lower clad layer) (FIG. 9 ( b) and FIG. 9 (c)).

Here, the core layer forming resin film of the present invention will be described by taking a core layer forming resin film having an intermediate part thinner than the end part as an example. This film can be manufactured by the same method as the above-described method for manufacturing a resin film for forming an optical waveguide.
As with the first clad layer forming resin film, the core layer forming resin film used here is preferably one in which a core layer forming resin is laminated on a base film, and a protective film (separator) is used if necessary. It has a laminated structure.

When laminating the core layer-forming resin film, it is preferable to laminate the core layer-forming resin film under reduced pressure from the viewpoint of adhesion and followability. The heating temperature here is preferably 50 to 130 ° C., and the pressure bonding pressure is preferably about 0.1 to 1.0 MPa (1 to 10 kgf / cm ² ). There is no particular limitation.
Moreover, it is preferable to laminate | stack using a roll laminator from a viewpoint of preventing mixing of the bubble between a 1st clad layer and a core layer.

  The resin film for forming a core layer used in the present invention can use a resin composition that is designed so that the core layer has a higher refractive index than that of the cladding layer and can form a core pattern with actinic rays. Compositions are preferred. Specifically, it is preferable to use the same resin composition as that used in the clad layer forming resin. That is, it is a resin composition containing the components (A), (B) and (C) and optionally containing the optional components.

  The resin film for forming a core layer can be easily produced by dissolving a resin composition containing the components (A) to (C) in a solvent, applying the resin composition to a base film, and removing the solvent. The solvent used here is not particularly limited as long as it can dissolve the resin composition. For example, acetone, methyl ethyl ketone, methyl cellosolve, ethyl cellosolve, toluene, N, N-dimethylformamide, N, N-dimethyl A solvent such as acetamide, propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, cyclohexanone, N-methyl-2-pyrrolidone, or a mixed solvent thereof can be used. The solid content concentration in the resin solution is usually preferably about 30 to 80% by mass.

The thickness of the resin film for forming the core layer is not particularly limited, and is appropriately determined according to the thickness of the core layer after drying. In the optical waveguide obtained by the present invention, the thickness of the core layer is different between at least one end portion and the other end portion (intermediate portion), and each has a desired thickness (II) step and (III) step The thickness of the resin film for forming a core layer used in is controlled.
The optical waveguide obtained by the present invention is adjusted so that the thickness of the core layer at the end is usually 10 to 100 μm. When the thickness of the core layer is 10 μm or more, there is an advantage that the alignment tolerance can be increased in the coupling with the light emitting / receiving element or the optical fiber after the optical waveguide is formed, and when the thickness is 100 μm or less, the light receiving / emitting after the optical waveguide is formed. In coupling with an element or an optical fiber, there is an advantage that coupling efficiency is improved. From the above viewpoints, the thickness of the core layer at the end is preferably in the range of 30 to 70 μm.
On the other hand, the thinner the core layer is, the more advantageous it is for bending durability, and a certain thickness is required from the viewpoint of suppressing optical loss. From the above viewpoint, the minimum thickness of the core layer at the intermediate portion is preferably in the range of 30 to 80%, more preferably in the range of 40 to 60% with respect to the thickness of the end portion.

When the core layer-forming resin film is obtained by forming the core layer-forming resin on the base film, the base film and the core layer-forming resin film are composed of the core layer-forming resin alone. In this case, the material of the base film used in the process of manufacturing the resin film for forming the core layer is not particularly limited, but it is easy to peel off later, and has a viewpoint of heat resistance and solvent resistance. Preferred examples thereof include polyesters such as polyethylene terephthalate, polypropylene, and polyethylene.
Moreover, it is preferable that the thickness of this base film is 5-50 micrometers. When it is 5 μm or more, there is an advantage that the strength as a support is easily obtained, and when it is 50 μm or less, there is an advantage that a gap with the mask at the time of pattern formation becomes small and a finer pattern can be formed. From the above viewpoint, the thickness of the base film is more preferably in the range of 10 to 40 μm, and particularly preferably 15 to 30 μm.

Moreover, it is preferable to use a highly transparent flexible base material in order to improve the transmittance of exposure light and reduce the side wall roughness of the core pattern. The haze value of the highly transparent base film is preferably 5% or less, more preferably 3% or less, and particularly preferably 2% or less. The haze value is measured in accordance with JIS K7105, and can be measured with a commercially available turbidimeter such as NDH-1001DP (manufactured by Nippon Denshoku Industries Co., Ltd.). Such a base film is available from Toyobo Co., Ltd. under the trade names “Cosmo Shine A1517” and “Cosmo Shine A4100”.
In addition, in order to make peeling easily, the said base film may be subjected to mold release treatment, antistatic treatment or the like.

(III) Process (III) Process is a process of patterning the core layer 53. As a patterning method, various methods can be used, but it is preferable to carry out exposure and development using a photosensitive resin as the core layer forming resin. When there is a base film of the core layer forming resin film as shown in FIG. 9C, the exposure and development are performed after the base film is removed (see FIG. 9D). In the laminated body after patterning, a cross-sectional view at the end of FIG. 9 (d) is FIG. 11 (a), and a cross-sectional view at the intermediate part of FIG. 9 (d) is FIG.
As an exposure method, specifically, an actinic ray is irradiated in an image form through a negative mask pattern. Examples of the active light source include known light sources that effectively emit ultraviolet rays, such as carbon arc lamps, mercury vapor arc lamps, ultrahigh pressure mercury lamps, high pressure mercury lamps, and xenon lamps. In addition, those that effectively emit visible light, such as a photographic flood bulb and a solar lamp, can be used.

Next, after the post-exposure heating as necessary, if the base film of the core layer forming resin film remains, the base film is peeled off, and the unexposed portion is removed by wet development, dry development, or the like. To develop a core pattern. In the case of wet development, among organic solvents, alkaline aqueous solutions, aqueous developers, etc., using a developer corresponding to the composition of the resin film, for example, by a known method such as spraying, rocking immersion, brushing, scraping, etc. develop.
As the developer, an organic solvent, an alkaline aqueous solution or the like that is safe and stable and has good operability is preferably used. Examples of the organic solvent developer include 1,1,1-trichloroethane, N-methylpyrrolidone, N, N-dimethylformamide, N, N-dimethylacetamide, cyclohexanone, methyl isobutyl ketone, and γ-butyrolactone. It is done. These organic solvents may be added with water in the range of 1 to 20% by mass in order to prevent ignition.

  Examples of the base of the alkaline aqueous solution include alkali hydroxides such as lithium, sodium, or potassium hydroxide, alkali carbonates such as lithium, sodium, potassium, or ammonium carbonate or bicarbonate, potassium phosphate, and phosphoric acid. Alkali metal phosphates such as sodium and alkali metal pyrophosphates such as sodium pyrophosphate and potassium pyrophosphate are used. Examples of the alkaline aqueous solution used for development include a dilute solution of 0.1 to 5% by mass of sodium carbonate, a dilute solution of 0.1 to 5% by mass of potassium carbonate, and a dilute solution of 0.1 to 5% by mass of sodium hydroxide. Preferred examples include a solution and a dilute solution of 0.1 to 5% by mass sodium tetraborate. Moreover, it is preferable to make pH of the alkaline aqueous solution used for image development into the range of 9-14, and the temperature is adjusted according to the developability of the layer of the photosensitive resin composition. In the alkaline aqueous solution, a surfactant, an antifoaming agent, a small amount of an organic solvent for accelerating development, and the like may be mixed.

  The aqueous developer comprises water or an alkaline aqueous solution and one or more organic solvents. Examples of the alkaline substance include borax, sodium metasilicate, tetramethylammonium hydroxide, ethanolamine, ethylenediamine, diethylenetriamine, 2-amino-2-hydroxymethyl-1,3-propanediol, 1 , 3-diaminopropanol-2, morpholine and the like. The pH of the developer is preferably as low as possible within a range where the resist can be sufficiently developed, preferably pH 8-12, more preferably pH 9-10. Examples of the organic solvent include triacetone alcohol, acetone, ethyl acetate, alkoxyethanol having an alkoxy group having 1 to 4 carbon atoms, ethyl alcohol, isopropyl alcohol, butyl alcohol, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol mono And butyl ether. These are used alone or in combination of two or more. The concentration of the organic solvent is usually preferably 2 to 90% by mass, and the temperature can be adjusted according to the developability. Further, a small amount of a surfactant, an antifoaming agent or the like can be mixed in the aqueous developer.

Moreover, you may use together 2 or more types of image development methods as needed. Examples of the development method include a dip method, a battle method, a spray method such as a high-pressure spray method, brushing, and slapping.
As the treatment after development, the core pattern may be further cured and used by heating at about 60 to 250 ° C. or exposure at about 0.1 to 1000 mJ / cm ² as necessary.

Step (IV) The step (IV) is a step of embedding the core pattern by forming the core layer 53 on the core pattern obtained by a method such as exposure and development and the second cladding layer 55 on the first cladding layer 52. (See FIGS. 9 (e) and 9 (f)). Here, the second clad layer forming resin film will be described as an example in which both end portions are thicker than the intermediate portion.
In this step, it is preferable that after embedding the core pattern, the resin of the resin film for forming a clad layer is cured to form a second clad layer (upper clad layer).
At this time, it is preferable that the thickness of the second cladding layer is larger than the thickness of the core layer (core pattern). The second clad layer forming resin can be cured by light or heat in the same manner as the first clad layer is formed.
In particular, when the formation condition of the second cladding layer, for example, the material is a resin film, the upper cladding layer is tapered like the core layer by adjusting the lamination conditions (pressure, temperature, pressurization time). It is possible to have it.

The second clad layer forming resin film used here is the same as the first clad layer forming resin film or the core layer forming resin film, in which the clad layer forming resin is laminated on the base film. The protective film (separator) 64 is laminated as necessary. The material of the base film is the same as the base film in the first clad layer forming resin film. Further, the clad layer forming resin is the same as the clad layer forming resin in the first clad layer forming resin film.
In the case where a protective film is provided on the opposite side of the base film of the second clad layer forming resin film, the protective film is peeled off, and then the clad layer forming resin film is cured by light or heating, 2 clad layers are formed. The protective film is preferably not subjected to adhesion treatment in order to facilitate peeling from the clad layer forming resin film, and may be subjected to mold release treatment or antistatic treatment as necessary.

In the present invention, the base film of the resin film for forming a clad layer also serves as a support in the manufacturing process of the flexible optical waveguide. Since this base film can be larger than a silicon substrate or the like conventionally used as a support, it is easy to increase the area and can provide a flexible optical waveguide excellent in productivity. .
The base film may be left on one side of the flexible optical waveguide, but a flexible optical waveguide with less warpage can be produced by using a symmetrical structure with both surfaces peeled (see FIG. 9G). Moreover, the flexible optical waveguide can be thinned by peeling the base film.

  Moreover, it is preferable that a humidification process is included in the process of peeling a base film. This is because the humidification treatment can reduce the adhesion between the base film and the clad layer and can easily peel the base film without damaging the optical waveguide. The humidification treatment is preferably performed under high temperature and high humidity conditions, boiling conditions, pressure cooker conditions, and the like, since the treatment time can be shortened when heating is used in combination.

  As is clear from the description of the step (IV), the flexible optical waveguide of the present invention has a shape in which the core pattern is surrounded by the upper clad layer and the lower clad layer. Have.

Further, as shown in FIG. 12, it is preferable that the width of the upper clad layer is smaller than the width of the lower clad layer in the middle part (FIG. 12 shows a perspective view seen from the upper clad side). This is because the bending durability is further improved by the narrow width of the upper cladding layer. The smaller the width of the upper clad layer in the intermediate part, the better the bending durability in the intermediate part. However, in order to exert a sufficient function as the clad layer, the upper clad layer completely covers the core part. The width is required to be embedded and maintain good light propagation characteristics. Considering the above points, the width x of the upper cladding layer is preferably about 20 to 60%, more preferably 20 to 50% with respect to the width y of the lower cladding layer.
Thus, as a method of making the width of the upper clad layer smaller than the width of the lower clad layer in the intermediate portion, the second clad layer forming resin film is exposed and developed, and the core pattern is embedded. There is a method of forming a second clad layer (upper clad layer) 7 having a smaller width than the first clad layer (lower clad layer) 2 in the intermediate portion. In addition, an upper clad layer forming resin film having a shape in which the width of the upper clad layer in the intermediate portion is smaller than the width of the lower clad layer is prepared in advance, and this is laminated on the core pattern. A method of embedding the core pattern can also be used.

  In the above, the manufacturing process of the optical waveguide using the resin film for optical waveguide formation whose film thickness of an intermediate part is thinner than an edge part was demonstrated. Since the optical waveguide produced here has a portion whose film thickness is thinner than the end portion, it is excellent in flexibility. On the other hand, an optical waveguide having a thick intermediate portion can be produced by using a resin film for forming an optical waveguide having a thicker intermediate portion than the end portion as shown in FIG. In the optical waveguide having such a structure, improvement in mechanical strength and environmental resistance of the optical waveguide can be expected.

By combining the flexible optical waveguide of the present invention with a flexible electrical circuit board (hereinafter referred to as FPC), a flexible type opto-electric composite circuit board can be produced. In the photoelectric composite wiring board combined with the FPC, the entire thickness increases by the FPC. Therefore, it is very important to have a thin portion of the optical waveguide in order to improve the flexibility.
As a method of compounding, in addition to a method of laminating separately manufactured optical waveguides and electrical wiring boards using an adhesive, etc., a method of building up an optical waveguide on an FPC, and a polyimide with copper foil Another example is a method of forming an FPC after forming an optical waveguide on a top by patterning a copper circuit.

Examples of the configuration of the optoelectric composite wiring board of the present invention include, for example, one in which an optical waveguide is bonded to one side of an electrical wiring board. Moreover, you may have an optical waveguide on both surfaces of an electrical wiring board. With such a configuration, the number of optical wirings of the photoelectric composite wiring board can be increased, and the optical transmission capacity can be increased. Moreover, since it becomes a vertically symmetrical structure, the warpage of the photoelectric composite wiring board can be suppressed.
Moreover, the structure which has an adhesive bond layer on both sides of an optical waveguide, and has an electrical wiring board on both surfaces may be sufficient. By adopting such a configuration, a vertically symmetrical structure is obtained, so that it is possible to suppress warpage of the photoelectric composite wiring board and to improve bending resistance. Note that the electrical wiring board does not necessarily have to be provided on both sides, and for the purpose of suppressing warpage and improving bending resistance, a material having the same physical properties as the electrical wiring board, such as a base material of the electrical wiring board or an electrical insulating layer, is used. A cover film may be provided on the opposite side of the electric wiring board.
Furthermore, a structure in which the optical waveguide and the opto-electric composite circuit board are multilayered may be used. With such a configuration, the signal transmission capacity can be further increased.

EXAMPLES The present invention will be described more specifically with reference to examples. However, the present invention is not limited to these examples.
1. Tensile modulus and tensile strength From a film to be measured, a sample having a width of 10 mm and a length of 70 mm was obtained, and a tensile tester (“RTM-100” manufactured by Orientec Co., Ltd.) was used in accordance with JIS-K7127. Measurement was performed under the following conditions.
Conditions: distance between grippers 50 mm, temperature 25 ° C., pulling speed 50 mm / min
The tensile elastic modulus was calculated by the following formula using the first linear portion of the tensile stress-strain curve. In the tensile stress-strain curve, the maximum strength until breakage was taken as the tensile strength.
1. Tensile modulus (MPa) = Stress difference between two points on a straight line (N) ÷ Original average cross-sectional area of optical waveguide film (mm ² ) ÷ Strain difference between the same two points Bending durability test For the photoelectric composite wiring boards manufactured in each of the examples and comparative examples, a bending durability test was performed using a sliding bending durability testing machine (manufactured by Daisho Electronics Co., Ltd.) as shown in FIG. Went. The test was performed on the photoelectric composite wiring board 71 obtained in each of the examples and comparative examples with the flexible optical waveguide disposed inside the bending shaft 74. Also, the bending radius (R), carried out under the condition of 1.5 mm, slide speed 80 mm / sec, the test under the conditions of a distance 20mm between X ¹ to X ² was carried out. About evaluation, the presence or absence of a fracture | rupture was observed every 5,000-50,000 times, and the maximum frequency | count which does not fracture | rupture was calculated | required. The bending shaft 74 does not actually exist, but is a virtual axis when the photoelectric composite wiring board is bent and slid.

Example 1
(1) Production of Cladding Layer Forming Resin Film (1-1) Lower Cladding Layer Forming Resin Film (A) As Binder Polymer, Phenoxy Resin (Product Name: Phenototope YP-70, Toto Kasei Co., Ltd.) 48 (C) As alicyclic diepoxycarboxylate (trade name: KRM-2110, molecular weight: 252, manufactured by Asahi Denka Kogyo Co., Ltd.), (C) As a light or thermal polymerization initiator, triphenylsulfonium hexafluoroantimonate salt (trade name: SP-170, manufactured by Asahi Denka Kogyo Co., Ltd.) 2 parts by mass, and as a sensitizer, SP-100 (trade name, Asahi Denka) (Made by Kogyo Co., Ltd.) 0.4 parts by mass, 40 parts by mass of propylene glycol monomethyl ether acetate as an organic solvent were weighed into a wide-mouthed plastic bottle, and mechanical star , Using a shaft and a propeller, the temperature 25 ° C., at a rotation speed 400rpm conditions, was stirred for 6 hours to prepare a resin varnish A for forming a cladding layer. After that, using a polyfluorone filter (trade name: PF020, manufactured by Advantech Toyo Co., Ltd.) with a pore size of 2 μm, it is filtered under pressure at a temperature of 25 ° C. and a pressure of 0.4 MPa, and further reduced in pressure using a vacuum pump and a bell jar. Degassed under reduced pressure for 15 minutes under the condition of a degree of 50 mmHg.
The clad layer-forming resin varnish A obtained above was coated on a corona-treated surface of an aramid film (trade name: Miktron, manufactured by Toray Industries, Inc., thickness: 12 μm) (Multicoater TM-MC, ( Coated with Hirano Techseed Co., Ltd., dried at 80 ° C. for 10 minutes, then at 100 ° C. for 10 minutes, and then released as a protective film PET film (trade name: Purex A31, Teijin DuPont Films, Inc.) 25 μm) was attached so that the release surface was on the resin side, and a resin film 1 for forming a cladding layer was obtained. At this time, the thickness of the resin layer can be arbitrarily adjusted by adjusting the gap of the coating machine. In this embodiment, the thickness of the resin layer is adjusted to 20 μm, and the lower clad layer is adjusted. A forming resin film 1 was obtained.
(1-2) Upper Cladding Layer Forming Resin Film Similar to the above lower clad layer forming resin film, a clad layer forming resin film 1 having a thickness of 34 μm is prepared. An upper clad layer forming resin film 1 having a thickness of 68 μm and a width of 80 mm at an intermediate portion of 34 μm was produced. First, the protective film of the clad layer forming resin film 1 cut to a width of 150 mm was peeled off to obtain a first upper clad layer forming resin film. Next, the release PET film (trade name: PUREX A31, Teijin DuPont Films, Inc., thickness: 25 μm) cut to a width of 80 mm is used as a masking film, and the center of the first resin film for forming the upper cladding layer The first clad layer forming resin film 1 is placed in contact with the release surface side, cut to a width of 150 mm, and the protective film is peeled off as a second upper clad layer forming resin film so that the clad layers overlap each other. Were laminated on the entire surface of the upper clad layer forming resin film and the release PET film. For lamination, a vacuum pressurization type laminator (MVLP-500, manufactured by Meiki Seisakusho Co., Ltd.) was used as a flat plate laminator. The lamination conditions were evacuated at 500 Pa or less for 7 seconds, pressure 0.4 MPa, temperature The temperature was 50 ° C. and the pressing time was 30 seconds. Thereafter, the aramid film as the support film for the second upper clad layer forming resin film is peeled off, and the second upper clad layer forming resin on the masking film is peeled off together with the masking film, and the width of 35 mm is removed. An upper clad layer-forming resin film 1 having a thickness of both ends of 68 μm and a width of 80 μm and an intermediate portion of 34 μm was obtained.

(2) Preparation of resin film for forming core layer (A) As binder polymer, 26 parts by mass of phenoxy resin (trade name: Phenototope YP-70, manufactured by Toto Kasei Co., Ltd.), (B) photo or thermopolymerizable compound As a product, 36 parts by mass of 9,9-bis [4- (2-acryloyloxyethoxy) phenyl] fluorene (trade name: A-BPEF, manufactured by Shin-Nakamura Chemical Co., Ltd.) and bisphenol A type epoxy acrylate (trade name) : EA-1020, manufactured by Shin-Nakamura Chemical Co., Ltd.) 36 parts by mass, (C) bis (2,4,6-trimethylbenzoyl) phenylphosphine oxide (trade name: Irgacure 819) as light or thermal polymerization initiator 1 part by weight of Ciba Specialty Chemicals) and 1- [4- (2-hydroxyethoxy) phenyl] -2-hydroxy-2 -Methyl-1-propan-1-one (trade name: Irgacure 2959, manufactured by Ciba Specialty Chemicals) 1 part by weight, except that 40 parts by weight of propylene glycol monomethyl ether acetate was used as the organic solvent Resin varnish B for forming a core layer was prepared in the same manner and conditions. Thereafter, pressure filtration and degassing under reduced pressure were carried out under the same method and conditions as in the above production example.
The resin layer varnish B for core layer formation obtained above is applied to a non-treated surface of a PET film (trade name: Cosmo Shine A1517, manufactured by Toyobo Co., Ltd., thickness: 16 μm) in the same manner as in the above production example. Then, release PET film (trade name: PUREX A31, Teijin DuPont Films Co., Ltd., thickness: 25 μm) is applied as a protective film so that the release surface is on the resin side to form the core layer Resin film 1 was obtained. In this example, the gap of the coating machine was adjusted so that the film thickness was 40 μm.
Subsequently, a resin film for forming a core layer having a thickness of both ends of 25 mm in width of 76 μm and a thickness of an intermediate portion of 90 mm in width of 38 μm was produced by the following steps. First, the protective film of the core layer forming resin film 1 cut to a width of 130 mm was peeled off to obtain a first core layer forming resin film. Next, using a release PET film (trade name: Purex A31, Teijin DuPont Films, Inc., thickness: 25 μm) cut to a width of 90 mm as a masking film, the center of the first core layer forming resin film The core layer forming resin film 1 which is placed so that the release surface side is in contact with each other, cut to a width of 130 mm and the protective film is peeled off is used as the second core layer forming resin film, so that the core layers overlap each other. It was laminated on the entire surface of the resin film for core layer formation and the release PET film. For lamination, a vacuum pressurization type laminator (MVLP-500, manufactured by Meiki Seisakusho Co., Ltd.) was used as a flat plate laminator. The lamination conditions were evacuated at 500 Pa or less for 7 seconds, pressure 0.4 MPa, temperature The temperature was 50 ° C. and the pressing time was 30 seconds. After this, the PET film, which is the support film for the second core layer forming resin film, is peeled off, and the second core layer forming resin on the masking film is peeled off together with the masking film, and both end portions having a width of 25 mm. A core layer-forming resin film 2 having a thickness of 76 μm and a width of 90 μm at an intermediate portion of 38 μm was obtained.

(3) Production of flexible optical waveguide The release PET film (Purex A31), which is a protective film of the resin film 1 for forming the lower clad layer obtained above, is peeled off, and an ultraviolet exposure machine (manufactured by Oak Manufacturing Co., Ltd.) Exim-1172) was irradiated with 1 J / cm ^{2 of} ultraviolet rays (wavelength 365 nm) from the resin side (opposite side of the base film), and then heat-treated at 80 ° C. for 10 minutes, whereby the first clad layer as the first cladding layer A clad layer (hereinafter referred to as a lower clad layer) was formed (step (I)). The thickness of the lower cladding layer was about 20 μm.

Next, a roll laminator (HLM-1500, manufactured by Hitachi Chemical Technoplant Co., Ltd.) is used at the center of the lower clad layer, the pressure is 0.5 MPa, the temperature is 50 ° C., and the lamination speed is 0.2 m / min. For the purpose of smoothing, the above-mentioned core layer forming resin film 2 was laminated using a vacuum pressurizing laminator under the conditions of evacuation 30 seconds, pressure 0.4 MPa, temperature 50 ° C., and pressurization time 30 seconds ( (II) Process). Note that a SUS plate was used as a pressurizing material for the vacuum pressurizing laminator.
By the smoothing, the core layer has an inclination that becomes thin in a tapered shape from the end portion to the intermediate portion, and the inclination angle is 0.15 degrees.

Next, ultraviolet rays (wavelength 365 nm) were irradiated with 0.8 J / cm ² with a UV photomask through a negative photomask having a width of 50 μm, and then after exposure at 80 ° C. for 5 minutes, heating was performed. Thereafter, the PET film as the support film was peeled off, and the core pattern was developed using a developer (propylene glycol monomethyl ether acetate / N, N-dimethylacetamide = 7/3, mass ratio). Then, it wash | cleaned using the washing | cleaning liquid (isopropanol), and heat-dried at 100 degreeC for 10 minute (s), and obtained the core pattern ((III) process).

Subsequently, the resin film 1 for forming a clad layer was laminated as an upper clad layer under the same laminating conditions as described above. Furthermore, after the ultraviolet rays (wavelength of 405 nm) were irradiated on both surfaces in total 20 J / cm ² , an upper clad layer was formed by heat treatment at 160 ° C. for 1 hour (step (IV)), and a base film (aramid film) A flexible optical waveguide was prepared on the outside. Further, for this substrate film peeling, the flexible optical waveguide was treated under high temperature and high humidity conditions of 85 ° C./85% for 10 hours to produce a flexible optical waveguide from which the substrate film was removed.
Table 1 shows the film thicknesses of the lower clad layer, the core layer, and the upper clad layer at the end and the middle of the flexible optical waveguide fabricated.

In addition, when the refractive index of the core layer and the clad layer was measured by a prism coupler (Model2010) manufactured by Metricon, the core layer was 1.584 and the clad layer was 1.550 at a wavelength of 830 nm. Further, the insertion loss of the produced flexible optical waveguide (FIG. 9 (g)) is determined by using a surface-emitting laser (850 nm manufactured by EXFO, FLS-300-01-VCL) as a light source, and manufactured by Advantest Corporation as a light receiving sensor. , Q82214 was measured using GI-50 / 125 multimode fiber (NA = 0.20) as the input fiber and SI-114 / 125 multimode fiber (NA = 0.22) as the output fiber. 0.0 dB. As shown in Comparative Example 1 described later, in the flexible optical waveguide having a constant core thickness of 76 μm, the insertion loss was 0.8 dB. It was confirmed to be sufficiently small as 2 dB.
Moreover, as a result of measuring the tensile elasticity modulus and tensile strength of the obtained flexible optical waveguide by the above method, the tensile elasticity modulus was 2100 MPa and the tensile strength was 100 MPa.

(4) Production of photoelectric composite wiring board (4-1) Production of sheet adhesive HTR-860P-3 (manufactured by Teikoku Chemical Industry Co., Ltd., trade name, glycidyl group-containing acrylic rubber, molecular weight 1 million, Tg- 7 ° C) 100 parts by mass, YDCN-703 (manufactured by Toto Kasei Co., Ltd., trade name, o-cresol novolac type epoxy resin, epoxy equivalent 210), 5.4 parts by mass, YDCN-8170C (manufactured by Toto Kasei Co., Ltd.) Product name, 16.2 parts by mass of bisphenol F type epoxy resin, epoxy equivalent 157), PRIOFEN LF2882 (manufactured by Dainippon Ink and Chemicals, trade name, bisphenol A novolac resin), 15.3 parts by mass, NUCA-189 (Nihon Unicar Co., Ltd., trade name, γ-mercaptopropyltrimethoxysilane) 0.1 parts by mass, NUCA-1160 (Nihon Unica Co., Ltd., trade name, γ-ureidopropyltriethoxysilane) 0.3 parts by mass, A-DPH (Shin Nakamura Chemical Co., Ltd., trade name, dipentaerythritol hexaacrylate) 30 parts by mass, Irgacure 369 (Ciba Specialty Chemicals, trade name, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butanone-1-one: I-369) 1.5 parts by mass, cyclohexanone was added The mixture was stirred and mixed and vacuum degassed to obtain an adhesive varnish. This adhesive varnish was applied on a protective film made of 75 μm thick surface release-treated polyethylene terephthalate (Teijin Limited, Teijin Tetron Film: A-31), and dried by heating at 80 ° C. for 30 minutes. An adhesive sheet comprising an adhesive layer and a protective film was obtained. On the adhesive layer side of this adhesive sheet, a light-transmitting support substrate having a thickness of 80 μm (manufactured by Thermo Co., Ltd., low density polyethylene terephthalate / vinyl acetate / low density polyethylene terephthalate three-layer film: FHF- 100) were laminated together to produce a sheet-like adhesive comprising a protective film (surface release-treated polyethylene terephthalate), an adhesive layer, and a light-transmitting support substrate. The thickness of the adhesive layer was 10 μm.

(4-2) Production of photoelectric composite wiring board Using the roll laminator (HLM-1500, manufactured by Hitachi Chemical Technoplant Co., Ltd.), the pressure of 0.4 MPa, the temperature of 50 ° C., and the laminate of the flexible optical waveguide produced above. The laminate was laminated on the adhesive layer side of the sheet-like adhesive from which the protective film was peeled off under the condition of a speed of 0.2 m / min. Next, ultraviolet light (365 nm) is irradiated from the support substrate side of the sheet-like adhesive at 250 mJ / cm ² to reduce the adhesive force between the adhesive layer and the support substrate interface and peel off the support substrate. , An ultraviolet exposure machine (manufactured by Dainippon Screen Co., Ltd., MAP-1200-L) is attached to a predetermined portion of an FPC having an electric circuit pattern (base material: Kapton EN, 12.5 μm, copper circuit thickness: 5 μm) Positioning using the above-mentioned mask aligner mechanism, vacuuming for 30 seconds at 500 Pa or less using the above-described vacuum pressure laminator, followed by pressure bonding under conditions of pressure 0.4 MPa, temperature 100 ° C., and pressure time 30 seconds. After that, the flexible optical waveguide and the FPC were bonded by heating in a clean oven at 180 ° C. for 1 hour to obtain a photoelectric composite wiring board.
When the repeated slide test (bending durability test) of the obtained photoelectric composite wiring board was performed by the above method, the optical waveguide was not broken even after 500,000 times, and the bending durability (sliding durability) was good. ) (See Table 1).

Example 2
In Example 1, as the upper clad layer-forming resin film, instead of the upper clad layer-forming resin film 1, a constant clad layer-forming resin film 1 having a thickness of 68 μm was used. Thus, a flexible optical waveguide was produced. In addition, a photoelectric composite wiring board was produced in the same manner as in Example 1. In this case, the insertion loss was 1.0 dB, and in the repeated slide test of the photoelectric composite wiring board, although it was inferior to Example 1, the bending durability (sliding durability) was 100,000 to 500,000 times. (See Table 1).

Example 3
In Example 1, it replaced with the core layer formation resin film 2 as a core layer formation resin film, and it carried out similarly to Example 1 except having used the constant 38 layer thick resin film 1 for core layer formation. A photoelectric composite wiring board was produced. In this case, the insertion loss is 0.9 dB, and in the repeated slide test of the photoelectric composite wiring board, as in Example 1, there is no disconnection of the optical waveguide even after 500,000 times and good bending durability (slide Durability) (see Table 1).

Comparative Example 1
In Example 1, as a core layer forming resin film, instead of the core layer forming resin film 2, a constant core layer forming resin film 1 having a thickness of 76 μm was used, and as an upper clad forming resin film, The core thickness is 80 μm and the upper clad thickness is 15 μm, as in Example 1, except that the upper clad layer forming resin film 1 is replaced with the constant clad forming resin film 1 having a thickness of 68 μm. A flexible optical waveguide was prepared. In addition, a photoelectric composite wiring board was produced in the same manner as in Example 1. In this case, the insertion loss was 0.8 dB. However, in the repeated slide test of the photoelectric composite wiring board, the optical waveguide was broken after 5000 times, and sufficient bending durability (sliding durability) was not obtained ( (See Table 1).

  In the optical waveguide and the photoelectric composite wiring board using the optical waveguide forming resin film of the present invention, the film thickness of the core layer or the cladding layer of the optical waveguide can be arbitrarily controlled. Further, since it has excellent bending durability and little optical loss, it is extremely useful as a highly practical flexible optical waveguide.

1, 4, 7, 61, 81; Optical waveguide forming resin film 2, 5, 8, 51, 54, 56, 62, 82; Base film 3, 6, 9, 83; Optical waveguide forming resin layer 10 , 15, 21; base film (for first optical waveguide forming resin)
13, 18, 20; base film (for second optical waveguide forming resin)
11, 16, 22; first optical waveguide forming resin layers 14, 17, 19, 23, 24; second optical waveguide forming resin layer 12; masking film 52; first cladding layer (lower cladding) layer)
53; Core layer 55; Second clad layer (upper clad layer)
57, 58, 59; core pattern 61; resin film 63 for forming a clad layer; resin 64 for forming a clad layer; protective film (separator)
71; opto-electric composite wiring board 72; flexible optical waveguide 73; flexible electric wiring board (FPC)
74: Bending axis (virtual axis)

Claims (8)

  A method of manufacturing a resin film for forming an optical waveguide having portions having different thicknesses in the same film, wherein (I) a second optical waveguide is formed on at least one end on the first optical waveguide forming resin layer At least one end or both ends for forming the second optical waveguide forming resin layer on the first optical waveguide forming resin layer in the step (I) A masking film is disposed on a portion other than the portion, and the second light guide is formed on the entire surface of the first optical waveguide forming resin layer including both the portion on which the masking film is disposed and the portion on which the masking film is not disposed. At least one of the first optical waveguide forming resin layer is formed by forming a waveguide forming resin layer and removing the second optical waveguide forming resin layer on the masking film together with the masking film. Method of manufacturing an optical waveguide forming resin film for forming the second optical waveguide forming resin layer on or both ends. After the step (I), further, (II) a step on the surface of the first optical waveguide forming resin layer and the second optical waveguide forming resin layer is formed so that the film thickness changing portion has a tapered shape. method of manufacturing an optical waveguide forming resin film according to claim 1 comprising the step of smoothing. The method for producing a resin film for forming an optical waveguide according to claim 2 , wherein the smoothing is performed using a flat plate type vacuum pressure laminator. The method for producing a resin film for forming an optical waveguide according to any one of claims 1 to 3 , wherein the first resin layer for forming an optical waveguide is formed on a substrate. The method for producing a resin film for forming an optical waveguide according to claim 4 , further comprising (III) a step of removing the substrate after the step (I). Method of manufacturing an optical waveguide forming resin film according to claim 4 or 5 the substrate is a substrate film. The method for producing a resin film for forming an optical waveguide according to any one of claims 1 to 6 , wherein the first optical waveguide forming resin layer and / or the second optical waveguide forming resin layer is in a film form. A lower cladding layer, the optical waveguide manufacturing method of laminating the core pattern and an upper cladding layer in this order, the upper cladding layer, optical waveguide forming resin film produced by the production method according to any one of claims 1 to 7, A method of manufacturing an optical waveguide formed using

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