JP5360055B2 - Optical waveguide manufacturing method and optical waveguide - Google Patents

Abstract

An optical waveguide manufacturing method has a step of forming a lower clad layer by hardening a clad layer forming resin formed on a base material; a step of forming a core layer by laminating, on the lower clad layer, a resin film for forming the core layer; a step of forming a core pattern by exposing and developing the core layer; and a step of forming an upper clad layer by laminating, on the core pattern, a resin film for forming an upper clad layer, and hardening the clad layer forming resin.  At the time of laminating the resin film for forming the upper clad layer, laminating conditions are controlled so that the melt viscosity of the clad layer forming resin is 100-200Pa·s.  The optical waveguide is formed of a resin having a melt viscosity of 100-200Pa·s.  In the optical waveguide manufacturing method, the optical waveguide can be manufactured with high productivity, and no bubble is left between the core layer and the upper clad layer.

Description

  The present invention relates to an optical waveguide manufacturing method and an optical waveguide, and more particularly to an optical waveguide manufacturing method and an optical waveguide in which the optical waveguide can be manufactured with high productivity and no bubbles remain between the core layer and the upper cladding layer. is there.

  With the increase in information capacity, development of optical interconnection technology that uses optical signals not only for communication fields such as trunk lines and access systems but also for information processing in routers and servers is underway. Specifically, in order to use light for short-distance signal transmission between boards in a router or a server device or in a board, an opto-electric hybrid board in which an optical transmission line is combined with an optical transmission path has been developed. As an optical transmission line, it is desirable to use an optical waveguide that has a higher degree of freedom of wiring and can be densified than an optical fiber, and in particular, an optical waveguide that uses a polymer material with excellent workability and economy. Is promising.

  Since an optical waveguide coexists with an electric wiring board, high transparency and high heat resistance are required. As such an optical waveguide material, fluorinated polyimide (for example, Non-Patent Document 1) or epoxy resin (for example, Patent Document 1). ) Has been proposed.

  Although fluorinated polyimide has high heat resistance of 300 ° C. or higher and high transparency of 0.3 dB / cm at a wavelength of 850 nm, film formation requires heating conditions of 300 ° C. or more for several tens of minutes to several hours. For this reason, it is difficult to form a film on an electric wiring board. Further, since fluorinated polyimide has no photosensitivity, the optical waveguide production method by photosensitivity / development cannot be applied, and the productivity and the area increase are inferior. Furthermore, since an optical waveguide is produced using a method of applying a liquid material on a substrate and forming a film, the film thickness management is complicated, and the resin applied on the substrate is liquid before curing, There was a problem caused by the material form being liquid, for example, it was difficult to maintain the uniformity of the film thickness because the resin flowed on the substrate.

  On the other hand, the epoxy resin for forming an optical waveguide in which a photopolymerization initiator is added to a liquid epoxy resin can form a core pattern by a photosensitive / developing method, and some of the materials have high transparency and high heat resistance. There was a similar problem caused by being liquid.

Therefore, a dry film containing a radiation-polymerizable component is laminated on the substrate, and a predetermined amount of light is irradiated to cure the radiation at a predetermined location to form a clad, and develop an unexposed portion as necessary. Thus, a method of forming an optical waveguide having excellent transmission characteristics by forming a core portion and the like and further forming a cladding for embedding the core portion is useful. When this method is used, it is easy to ensure the flatness of the clad after embedding the core. It is also suitable for manufacturing a large-area optical waveguide. As a method of laminating a dry film on a substrate, a vacuum type having a vacuum chamber formed by a pair of block bodies relatively movable up and down as disclosed in FIGS. A so-called vacuum laminating method in which laminating is performed under a reduced pressure is known.
However, there is a problem that bubbles that enter when the core portion is embedded remain between the core layer and the upper clad layer, and there is a problem that loss increases when an optical signal passes through the bubbles. In particular, the wiring density of the core portion, which has been conventionally required, is about 50 μm / 200 μm between the line width / line. For example, when producing an optical waveguide with a narrow pitch such as 50 μm / 50 μm between the line width / line. The effect of air bubbles was significant. In addition, when the core portion is embedded, improvement in the flatness of the upper cladding layer has been demanded.
JP-A-6-228274 Japanese Patent Laid-Open No. 11-320682 Journal of Japan Institute of Electronics Packaging, Vol. 7, no. 3, pp. 213-218, 2004

  The present invention has been made to solve the above-mentioned problems, and provides an optical waveguide manufacturing method and an optical waveguide that can manufacture an optical waveguide with high productivity and that no bubbles remain between a core layer and an upper cladding layer. The purpose is to do.

As a result of intensive studies to achieve the above object, the inventors of the present invention have made the clad layer forming resin have a melt viscosity of 100 to 200 Pa · s when the upper clad layer forming resin film is laminated. The lamination conditions are controlled, the upper clad layer is formed with a resin having a melt viscosity of 100 to 200 Pa · s at the time of lamination, or the upper clad layer forming resin is laminated on the support film on the core pattern. The present invention has been completed by finding that the above-mentioned object can be achieved by laminating a resin film for forming an upper clad layer to be in contact with the core pattern and then performing a heat treatment.
That is, the present invention
(1) A step of curing a resin for forming a cladding layer formed on a substrate to form a lower cladding layer, a step of forming a core layer by laminating a resin film for forming a core layer on the lower cladding layer, A step of exposing and developing the core layer to form a core pattern, and a step of laminating a resin film for forming an upper clad layer on the core pattern and curing the resin for forming the clad layer to form an upper clad layer A method for producing an optical waveguide comprising: controlling the lamination conditions so that the melt viscosity of the clad layer forming resin is 100 to 200 Pa · s when the upper clad layer forming resin film is laminated. An optical waveguide manufacturing method,
(2) The step of forming a core layer includes a step of thermocompression-bonding a resin film for forming a core layer on a lower clad layer using a roll laminator having a heat roll. Manufacturing method of optical waveguide,
(3) When laminating a resin film for forming an upper clad layer on a core pattern, the method for producing an optical waveguide according to the above (1), characterized in that it is thermocompression-bonded under a reduced pressure atmosphere using a flat plate laminator,
(4) In an optical waveguide in which a lower clad layer, a core pattern, and an upper clad layer are laminated in order on a substrate, the upper clad layer is formed of a resin having a melt viscosity of 100 to 200 Pa · s at the time of lamination. An optical waveguide,
(5) In an optical waveguide in which a lower clad layer, a core pattern, and an upper clad layer are sequentially laminated on a base material, the upper clad layer is formed from a resin having a melt viscosity of 100 to 200 Pa · s at 40 to 130 ° C. An optical waveguide,
(6) In an optical waveguide in which a lower clad layer, a core pattern, and an upper clad layer are sequentially laminated on a substrate, the upper clad layer is formed from a resin having a melt viscosity at 100 ° C. of 100 to 200 Pa · s. An optical waveguide,
(7) In an optical waveguide in which a lower clad layer, a core pattern, and an upper clad layer are sequentially laminated on a substrate, the upper clad layer contains a phenoxy resin-based pace polymer and a bifunctional epoxy resin, and is 90 to 120 ° C. An optical waveguide formed from a resin having a melt viscosity of 100 to 200 Pa · s,
(8) The melt viscosity is 120 to 180 Pa · s, The optical waveguide according to any one of claims 4 to 7,
(9) a step of curing a resin for forming a cladding layer formed on a substrate to form a lower cladding layer, a step of forming a core layer by laminating a resin film for forming a core layer on the lower cladding layer, A step of exposing and developing the core layer to form a core pattern; and an upper clad layer-forming resin film obtained by laminating an upper clad layer-forming resin on a support film on the core pattern. A method of manufacturing an optical waveguide, including a step of laminating so as to contact a pattern, a step of performing a heat treatment, and a step of curing the resin for forming a clad layer to form an upper clad layer;
(10) The method for producing an optical waveguide according to (9) above, wherein the heat treatment condition is a temperature of 40 to 200 ° C.
Is to provide.
Hereinafter, the manufacturing methods (1) to (3) may be referred to as a first manufacturing method, and the manufacturing methods (9) to (10) may be referred to as a second manufacturing method.

  According to the manufacturing method of the present invention, an optical waveguide can be manufactured with high productivity, and no bubbles remain between the core layer and the upper cladding layer.

It is a figure explaining an example of the manufacturing method of the optical waveguide of this invention. It is a figure explaining the resin film for clad layer formation used for the manufacturing method of the optical waveguide of this invention. It is a figure explaining the resin film for core layer formation used for the manufacturing method of the optical waveguide of this invention. It is a figure explaining another example of the manufacturing method of the optical waveguide of this invention. It is a microscope picture after an upper clad layer lamination and before heat processing. It is a microscope picture after heat processing after an upper clad layer lamination.

DESCRIPTION OF SYMBOLS 1; Base material 2; Lower clad layer 3; Core layer 4; Support film (for core layer formation)
5; roll laminator 6; vacuum pressure laminator 7; photomask 8; core pattern 9; upper clad layer 10; support film (for clad layer formation)
11; Protective film (protective layer)
20; resin for clad layer formation 30; resin for core layer formation 40; silicon substrate 200; resin film for clad layer formation 300; resin film for core layer formation

  An optical waveguide manufactured according to the present invention is an optical waveguide having a lower clad layer 2, a core pattern 8, and an upper clad layer 9 on a substrate 1, as shown in FIG. 1 core layer forming resin film (FIG. 3, 300) having a low refractive index and two clad layer forming resins having a low refractive index, preferably a clad layer forming resin film (FIG. 2, 200). can do. By using a film-like material, it is possible to solve the problems relating to productivity and large area response unique to liquid materials.

(Base material)
Although it does not restrict | limit especially as a kind of the base material 1, For example, FR-4 board | substrate, a polyimide, a semiconductor substrate, a silicon substrate, a glass substrate etc. can be used.
Moreover, by using a film as the substrate 1, flexibility and toughness can be imparted to the optical waveguide. The material of the film is not particularly limited, but from the viewpoint of having flexibility and toughness, polyesters such as polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polyethylene, polypropylene, polyamide, aramid, polycarbonate, polyphenylene ether, Preferred examples include polyether sulfide, polyarylate, liquid crystal polymer, polysulfone, polyether sulfone, polyether ether ketone, polyether imide, polyamide imide, and polyimide.
The thickness of the film may be appropriately changed depending on the intended flexibility, but is preferably 5 to 250 μm. If it is 5 μm or more, there is an advantage that toughness can be easily obtained, and if it is 250 μm or less, sufficient flexibility can be obtained.

As the substrate 1 shown in FIG. 1, a support film 10 used in the process of manufacturing a clad layer forming resin film 200 described later can be used. In this case, as the clad layer forming resin film 200, when the optical waveguide is manufactured and the support is provided outside the clad layer, the clad layer forming resin is formed on the support film 10 subjected to the adhesion treatment. 20 is preferably formed. Thereby, the adhesive force of the lower clad layer 2 and the base material 1 can be improved, and the peeling defect of the lower clad layer 2 and the base material 1 can be suppressed. Here, the adhesion treatment is a treatment for improving the adhesion force between the support film 10 and the clad layer forming resin 20 formed thereon by easy adhesion resin coating, corona treatment, mat processing by sandblasting, or the like. . On the other hand, when the support is peeled off after the optical waveguide is produced, the support film may be subjected to a release treatment as necessary.
Moreover, you may have a base material on the outer side of an upper clad layer, As a kind of this base material, the thing similar to the base material 1 mentioned above is mentioned, for example, as shown in FIG.1 (f) Examples thereof include a support film 10 used in the production process of a clad layer forming resin film 200 described later.

A multilayer optical waveguide may be produced by laminating a plurality of polymer layers having a core pattern and a clad layer on one or both surfaces of the substrate 1 described above.
Furthermore, an electrical wiring may be provided on the above-described base material 1, and in this case, a material provided with an electrical wiring in advance can be used as the base material 1. Alternatively, electrical wiring can be formed on the substrate 1 after manufacturing the optical waveguide. Thereby, both the signal transmission line of the metal wiring on the substrate 1 and the signal transmission line of the optical waveguide can be provided, both can be used properly, and signal transmission at a high speed and a long distance can be easily performed. Can do.

(Clad layer forming resin and clad layer forming resin film)
Hereinafter, the clad layer forming resin and the clad layer forming resin film (FIG. 2, 200) used in the present invention will be described in detail.
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 a thermosetting resin composition or a photosensitive resin composition is used. It can be preferably used. More preferably, the clad layer forming resin is composed of a resin composition containing (A) a base polymer (also referred to as a binder polymer), (B) a photopolymerizable compound, and (C) a photopolymerization initiator. preferable. The resin composition used for the cladding layer forming resin may be the same or different in the components contained in the resin composition in the upper cladding layer 9 and the lower cladding layer 2. The refractive indexes may be the same or different.

  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. Further, compatibility with the photopolymerizable compound (B) described in detail later is important for ensuring the transparency of the resin for forming the cladding layer. From this point, the phenoxy resin and the (meth) acrylic resin are used. Is preferred. Here, (meth) acrylic resin means acrylic resin and methacrylic resin.

  Among phenoxy resins, those containing bisphenol A, bisphenol A-type epoxy compounds or derivatives thereof, and bisphenol F, bisphenol F-type epoxy compounds or derivatives thereof as constituent units of copolymer components are heat resistant, adhesive and soluble. It is preferable because of its excellent properties. 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.

  Examples of the epoxy resin that is solid at room temperature include, for example, “Epototo YD-7020, Epototo YD-7019, Epototo YD-7007” (all trade names) manufactured by Toto Chemical Co., Ltd., and “Epicoat 1010” manufactured by Japan Epoxy Resins Co., Ltd. Bisphenol A type epoxy resin such as “Epicoat 1009, Epicoat 1008” (both trade names).

Next, (B) the photopolymerizable compound is not particularly limited as long as it is polymerized by irradiation with light such as ultraviolet rays, and the compound having an ethylenically unsaturated group in the molecule or two or more in the molecule. Examples thereof include compounds having an epoxy group.
Examples of the compound having an ethylenically unsaturated group in the molecule include (meth) acrylate, vinylidene halide, vinyl ether, vinyl pyridine, vinyl phenol, etc., among these, from the viewpoint of transparency and heat resistance, (Meth) acrylate is preferred.
As the (meth) acrylate, any of monofunctional, bifunctional, trifunctional or higher polyfunctional ones can be used. Here, (meth) acrylate means acrylate and methacrylate.
Examples of the compound having two or more epoxy groups in the molecule include bifunctional or polyfunctional aromatic glycidyl ethers such as bisphenol A type epoxy resins, bifunctional or polyfunctional aliphatic glycidyl ethers such as polyethylene glycol type epoxy resins, and water. Bifunctional alicyclic glycidyl ether such as bisphenol A type epoxy resin, bifunctional aromatic glycidyl ester such as diglycidyl phthalate, bifunctional alicyclic glycidyl ester such as tetrahydrophthalic acid diglycidyl ester, N, N- Bifunctional or polyfunctional aromatic glycidylamine such as diglycidylaniline, bifunctional alicyclic epoxy resin such as alicyclic diepoxycarboxylate, bifunctional heterocyclic epoxy resin, polyfunctional heterocyclic epoxy resin, bifunctional Or polyfunctional silicon-containing epoxy resin Etc., and the like. These (B) photopolymerizable compounds can be used alone or in combination of two or more.

  Next, the photopolymerization initiator of component (C) is not particularly limited. For example, as an initiator when an epoxy compound is used as component (B), aryldiazonium salt, diaryliodonium salt, triarylsulfonium salt, triallyl Examples include selenonium salts, dialkylphenazylsulfonium salts, dialkyl-4-hydroxyphenylsulfonium salts, and sulfonate esters.

  Moreover, as an initiator in the case of using a compound having an ethylenically unsaturated group in the molecule as the component (B), aromatic ketones such as benzophenone, quinones such as 2-ethylanthraquinone, benzoin ethers such as benzoin methyl ether Compounds, benzoin compounds such as benzoin, benzyl derivatives such as benzyldimethyl ketal, 2,4,5-triarylimidazole dimers such as 2- (o-chlorophenyl) -4,5-diphenylimidazole dimer, 2- Benzimidazoles such as mercaptobenzimidazole, phosphine oxides such as bis (2,4,6-trimethylbenzoyl) phenylphosphine oxide, acridine derivatives such as 9-phenylacridine, N-phenylglycine, N-phenylglycine derivatives , Coumarin compound And the like. 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) photopolymerization initiators can be used alone or in combination of two or more.

(A) It is preferable that the compounding quantity of a base polymer shall be 5-80 mass% with respect to the total amount of (A) component and (B) component. Moreover, it is preferable that the compounding quantity of (B) photopolymerizable compound shall be 95-20 mass% with respect to the total amount of (A) and (B) component.
When the blending amount of the component (A) and the component (B) is such that the component (A) is 5% by mass or more and the component (B) is 95% by mass or less, the resin composition is easily formed into a film. Can do. On the other hand, when the component (A) is 80% by mass or less and the component (B) is 20% by mass or more, the (A) base polymer can be easily entangled and cured, and an optical waveguide is formed. The pattern forming property is improved and the photocuring reaction proceeds sufficiently. From the above viewpoint, the blending amount of the component (A) and the component (B) is more preferably 10 to 75% by mass of the component (A) and 90 to 25% by mass of the component (B), and the component 20 to 70. More preferably, the content is 80% by mass and 80% by mass of the component (B).
(C) It is preferable that the compounding quantity of a photoinitiator shall be 0.1-10 mass parts with respect to 100 mass parts of total amounts of (A) component and (B) component. When the blending amount is 0.1 parts by mass or more, the photosensitivity is sufficient, while when it is 10 parts by mass or less, the light absorption in the surface layer of the resin composition does not increase at the time of exposure. Photocuring is sufficient. Furthermore, when used as an optical waveguide, it is preferable that the propagation loss does not increase due to the light absorption effect of the polymerization initiator itself. From the above viewpoint, the blending amount of the (C) photopolymerization initiator is more preferably 0.2 to 5 parts by mass.

  In addition, if necessary, in the cladding layer forming resin, an antioxidant, an anti-yellowing agent, an ultraviolet absorber, a visible light absorber, a colorant, a plasticizer, a stabilizer, a filler, etc. You may add what is called an additive in the ratio which does not have a bad influence on the effect of this invention.

The resin film for forming a clad layer (FIGS. 2 and 200) is obtained by dissolving the resin composition containing the components (A) to (C) in a solvent, applying the resin composition to the support film 10, and removing the solvent. Can be manufactured more easily.
The support film 10 used in the manufacturing process of the clad layer forming resin film 200 is not particularly limited with respect to the material thereof, and various films can be used. From the viewpoints of flexibility and toughness as the support film, those exemplified as the film material of the substrate 1 described above can be similarly mentioned.
The thickness of the support film 10 may be appropriately changed depending on the intended flexibility, but is preferably 5 to 250 μm. When it is 5 μm or more, toughness is obtained, and when it is 250 μm or less, sufficient flexibility is obtained. Moreover, when performing a heat processing, it is preferable that the thickness of the support body film 10 is 5-40 micrometers. If it is 5 μm or more, sufficient toughness can be obtained, and if it is 40 μm or less, bubbles can be eliminated without setting the heating temperature high.
At this time, the protective film 11 may be bonded to the clad layer forming resin film 200 as necessary from the viewpoints of protection of the clad layer forming resin film 200 and winding property when manufacturing in a roll shape. As the protective film 11, the thing similar to what was mentioned as the example as the support body film 10 can be used, and the mold release process and the antistatic process may be performed as needed.
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, propylene A solvent such as 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 lower clad layer 2 and the upper clad layer 9 (hereinafter, abbreviated as clad layers 2 and 9), 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 layers 2 and 9 is more preferably in the range of 10 to 100 μm.

  The thickness of the clad layers 2 and 9 may be the same or different in the lower clad layer 2 formed first and the upper clad layer 9 for embedding the core pattern, but the core pattern is buried. Therefore, the thickness of the upper clad layer 9 is preferably thicker than the thickness of the core layer 3.

(Core layer forming resin film)
Next, the core layer forming resin film (FIGS. 3 and 300) used in the present invention will be described in detail.
The core layer forming resin 30 constituting the core layer forming resin film 300 is a resin that is designed such that the core layer 3 has a higher refractive index than the clad layers 2 and 9 and can form the core pattern 8 by actinic rays. A composition can be used, and a photosensitive resin composition is preferred. Specifically, the same resin composition as that used in the resin for forming a cladding layer, that is, the components (A), (B) and (C) are contained, and the optional components are contained as necessary. It is preferable to use a resin composition.

  The resin film 300 for forming the core layer can be easily manufactured by dissolving the resin composition containing the components (A) to (C) in a solvent, applying the resin composition to the support film 4, and removing the solvent. it can. The solvent is not particularly limited as long as it can dissolve the resin composition, and those exemplified as the solvent used for producing the resin film for forming a clad layer can be similarly used. The solid concentration in the resin solution is preferably about 30 to 80% by mass.

  The thickness of the core layer-forming resin film 300 is not particularly limited, and the thickness of the core layer 3 after drying is usually adjusted to be 10 to 100 μm. When the thickness of the film 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 forming the optical waveguide, and when the thickness is 100 μm or less, the receiving after the optical waveguide is formed. There is an advantage that coupling efficiency is improved in coupling with a light emitting element or an optical fiber. From the above viewpoint, the thickness of the film is preferably in the range of 30 to 70 μm.

The support film 4 used in the manufacturing process of the core layer forming resin film 300 is a support film that supports the core layer forming resin 30 and the material thereof is not particularly limited. From the viewpoint that it is easy to peel off and has heat resistance and solvent resistance, polyesters such as polyethylene terephthalate, polypropylene, polyethylene and the like are preferable.
The thickness of the support film 4 is preferably 5 to 50 μm. When it is 5 μm or more, there is an advantage that the strength as the support film 4 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 support film 4 is more preferably in the range of 10 to 40 μm, and particularly preferably 15 to 30 μm.
From the viewpoints of protection of the core layer forming resin film 300 and rollability when manufacturing in a roll shape, the protective film 11 may be bonded to the core layer forming resin film 300 as necessary. As the protective film 11, the thing similar to what was mentioned as the example as the support body film 4 can be used, and the mold release process and the antistatic process may be performed as needed.

(Optical waveguide manufacturing method)
Hereafter, the manufacturing method of the optical waveguide of this invention is explained in full detail (refer FIG. 1). In the following production examples, an example of an embodiment in which a clad layer forming resin film (FIGS. 2 and 200) and a core layer forming resin film (FIGS. 3 and 300) are used will be specifically described.
First, as a first step, the clad layer forming resin 20 (FIG. 2, 200) composed of the clad layer forming resin 20 and the support film 10 is used to light or heat the clad layer forming resin 20. Curing is performed to form the lower clad layer 2 (FIG. 1A). At this time, the support film 10 becomes the base material 1 of the lower cladding layer 2 shown in FIG.
The curing conditions by light or heating vary depending on the type of resin for forming the cladding layer, but the solvent used in the manufacturing process of the resin film for forming the cladding layer is volatilized to ensure complete adhesion with the core layer 3. It is preferable not to cure. This is to prevent adverse effects such as erosion of the solvent by the solvent when the upper clad layer is later laminated.
For example, in the case of a clad layer forming resin containing a phenoxy resin type as a base polymer and a bifunctional epoxy resin as a photopolymerizable compound, it may be cured at a temperature of 90 to 150 ° C. for about 10 to 120 minutes.
The lower cladding layer 2 is preferably flat without a step on the surface on the core layer lamination side, from the viewpoint of adhesion to the core layer described later. Moreover, the surface flatness of the clad layer 2 can be ensured by using the resin film for forming the clad layer.
As shown in FIG. 2, when the protective film 11 is provided on the opposite side of the support film 10 of the clad layer forming resin film 200, the clad layer forming resin 20 is irradiated with light or The clad layer 2 is formed by curing by heating. At this time, the clad layer forming resin 20 is preferably formed on the support film 10 subjected to the adhesion treatment. On the other hand, the protective film 11 is preferably not subjected to an adhesion treatment in order to facilitate peeling from the clad layer forming resin film 200, and may be subjected to a mold release treatment as necessary.

Next, the core layer 3 is formed on the lower clad layer 2 by a second step described in detail below. In this second step, the core layer forming resin film 300 is laminated on the lower cladding layer 2 to form the core layer 3 having a higher refractive index than the lower cladding layer 2.
Specifically, as a second step, the core layer forming resin film 300 is bonded onto the lower cladding layer 2 and the core layer 3 is laminated. A roll laminator or a flat plate laminator can be used for the lamination.
For example, when using the roll laminator 5 (FIG. 1 (b)), it is preferable to laminate while crimping from the viewpoint of improving adhesion and followability, and when laminating, a laminator having a heat roll is used for heating. It is preferable to do so. When a roll laminator is used, the bubble entrainment laminating temperature is preferably in the range of room temperature (25 ° C.) to 100 ° C. When the temperature is higher than room temperature, the adhesion between the lower clad layer and the core layer is improved, and when the temperature is 40 ° C. or higher, the adhesion can be further improved. On the other hand, if it is 100 ° C. or lower, the required film thickness can be obtained without the core layer flowing during roll lamination. From the above viewpoint, the range of 40 to 100 ° C. is more preferable. The pressure is preferably 0.2 to 0.9 MPa. The laminating speed is preferably 0.1 to 3 m / min, but these conditions are not particularly limited.
On the other hand, in the case of using the flat plate laminator 6 (FIG. 1C), it is preferable to perform in a reduced pressure atmosphere at the time of thermocompression bonding from the viewpoint of improving adhesion and followability. In the present invention, the flat plate laminator refers to a laminator in which a laminated material is sandwiched between a pair of flat plates and pressed by pressing the flat plates. As the flat plate laminator, for example, a vacuum pressurizing laminator described in Patent Document 2 can be suitably used. The upper limit of the degree of vacuum, which is a measure of pressure reduction, is preferably 10,000 Pa or less, and more preferably 1000 Pa or less. The degree of vacuum is preferably low from the viewpoint of adhesion and followability. On the other hand, the lower limit of the degree of vacuum is preferably about 10 Pa from the viewpoint of productivity (the time required for evacuation). The heating temperature is preferably 40 to 130 ° C., and the pressing pressure is preferably 0.1 to 1.0 MPa (1 to 10 kgf / cm ² ), but these conditions are not particularly limited.
A roll laminator is preferably used from the viewpoint of reducing bubbles during lamination, and a flat plate laminator is used from the viewpoint of adhesion and flatness. Moreover, you may use these laminators together as needed.

The core layer forming resin film 300 is preferably composed of the core layer forming resin 30 and the support film 4 from the viewpoint of handleability. In this case, the core layer forming resin 30 is disposed on the lower clad layer 2 side. And laminate. The core layer forming resin film 300 may be composed of the core layer forming resin 30 alone.
As shown in FIG. 3, when the protective film 11 is provided on the opposite side of the base material of the core layer forming resin film 300, the core layer forming resin film 300 is laminated after the protective film 11 is peeled off. At this time, it is preferable that the protective film 11 and the support film 4 have not been subjected to an adhesive treatment in order to facilitate peeling from the core layer-forming resin film 300, and may be subjected to a release treatment as necessary. Good.

  Next, as a third step, the core layer 3 is exposed and developed to form the core pattern 8 of the optical waveguide (FIGS. 1D and 1E). Specifically, actinic rays are irradiated in an image form through the photomask pattern 7. 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, when the support film 4 of the resin film 300 for core layer formation remains, the support film 4 is peeled off, and the unexposed portion is removed and developed by wet development or the like to form the core pattern 8. . In the case of wet development, development is performed by a known method such as spraying, rocking dipping, brushing, scraping, or the like, using an organic solvent developer suitable for the composition of the film.

  Examples of organic solvent developers include N-methylpyrrolidone, N, N-dimethylformamide, N, N-dimethylacetamide, cyclohexanone, methyl ethyl ketone, methyl isobutyl ketone, γ-butyrolactone, methyl cellosolve, ethyl cellosolve, propylene glycol monomethyl. Examples include ether and propylene glycol monomethyl ether acetate. 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 paddle method, a spray method such as a high-pressure spray method, brushing, and scraping. The high-pressure spray method is most suitable for improving the resolution.
As the treatment after development, by heating at about 60 to 250 ° C. (preferably at about 110 to 150 ° C. for about 10 to 120 minutes) or exposure at about 0.1 to 1000 mJ / cm ² as necessary, The core pattern 8 may be further cured and used so that the solvent is volatilized and erosion by the solvent does not occur.

Next, as a fourth step, a clad layer forming resin film 200 is laminated for embedding the core pattern 8. When the clad layer forming resin film 200 is composed of the clad layer forming resin 20 and the support film 10, the laminating is performed with the clad layer forming resin 20 facing the core pattern 8. At this time, the thickness of the clad layer 9 is preferably larger than the thickness of the core layer 3 as described above.
Lamination is preferably performed by heat-pressing the clad layer forming resin film 200 in a reduced pressure atmosphere (FIG. 1 (f)). Here, the fourth step is preferably performed in a reduced-pressure atmosphere at the time of thermocompression bonding from the viewpoint of improving adhesion and followability. More preferably, it is thermocompression bonding using a flat plate laminator 6 in a reduced pressure atmosphere. The upper limit of the degree of vacuum, which is a measure of pressure reduction, is preferably 10,000 Pa or less, and more preferably 1000 Pa or less. The degree of vacuum is preferably low from the viewpoint of adhesion and followability. On the other hand, the lower limit of the degree of vacuum is preferably about 10 Pa from the viewpoint of productivity (the time required for evacuation). The heating temperature is preferably 40 to 130 ° C., and the pressing pressure is preferably 0.1 to 1.0 MPa (1 to 10 kgf / cm ² ), but these conditions are not particularly limited.
Also, when the clad layer-forming resin film 200 is heat-pressed, at least one, and preferably both, are pressure-bonded using a stainless steel (SUS) plate, resulting in a uniform film thickness, compared with the case where a rubber plate is used. A flat upper cladding layer is formed.

  As shown in FIG. 2, when the protective film 11 is provided on the opposite side of the support film 10 of the clad layer forming resin film 200, the protective film 11 is peeled off and then the clad layer forming resin film 200 is laminated. Then, the clad layer 9 is formed by curing by light or heating. At this time, it is preferable that the clad layer forming resin 20 is formed on the support film 10 subjected to the adhesion treatment. On the other hand, the protective film 11 is preferably not subjected to an adhesive treatment in order to facilitate peeling from the clad layer forming resin film 200, and may be subjected to a release treatment as necessary.

  In the first production method of the present invention, the lamination conditions such as temperature, pressure, and time are set so that the melt viscosity of the clad layer forming resin becomes 100 to 200 Pa · s when the upper clad layer forming resin film is laminated. It is necessary to control the viscosity, and the melt viscosity is preferably 120 to 180 Pa · s. By controlling the lamination conditions so as to be within this viscosity range, no bubbles remain between the core and the upper cladding layer. If it is greater than 200 Pa · s, the resin viscosity is high and bubbles remain. On the other hand, when the viscosity is less than 100 Pa · s, the resin viscosity is low, which causes a problem that the resin flows out and the flatness deteriorates. Moreover, it is preferable that the said melt viscosity is a melt viscosity in 40-130 degreeC. When the temperature is higher than 40 ° C., a resin film having low tack at room temperature and excellent handleability can be obtained. On the other hand, when it is lower than 130 ° C., there is an advantage of excellent productivity. From these viewpoints, the melt viscosity is more preferably a melt viscosity at 50 to 100 ° C, and further preferably a melt viscosity at 100 ° C. By setting it as the melt viscosity of such a temperature range, the optical waveguide with which a bubble does not remain between a core layer and an upper clad layer is obtained, and the handleability of a resin film is also excellent.

The optical waveguide of the present invention is an optical waveguide in which a lower clad layer, a core pattern, and an upper clad layer are sequentially laminated on a substrate, and the upper clad layer has a melt viscosity of 100 to 200 Pa · s at the time of lamination. It is an optical waveguide formed from a certain resin.
The optical waveguide is an optical waveguide in which a lower clad layer, a core pattern, and an upper clad layer are sequentially laminated on a base material. The upper clad layer has a melt viscosity of 100 to 40 ° C, preferably 100 ° C. It may be an optical waveguide formed from a resin having a viscosity of ˜200 Pa · s, and the upper clad layer contains a phenoxy resin-based pace polymer and a bifunctional epoxy resin, and has a melt viscosity of 100 to 90 ° C. at 90 to 120 ° C. An optical waveguide formed from a resin having a pressure of 200 Pa · s is preferable.
The melt viscosity is preferably 120 to 180 Pa · s.

The resin having a melt viscosity of 100 to 200 Pa · s, preferably 120 to 180 Pa · s is selected from the types of base polymer and polymerizable compound (structure, molecular weight, glass transition temperature, viscosity, etc.) used as the resin composition. Alternatively, it can be obtained by appropriately adjusting the blending ratio thereof.
Examples of the base polymer include phenoxy resin, epoxy resin solid at room temperature, (meth) acrylic polymer, acrylic rubber, polyurethane, polyimide, polyamide, polyamideimide, polysiloxane and the like. Here, 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 in order to form a resin film. . The upper limit of the number average molecular weight is not particularly limited, but is preferably 1,000,000 or less, more preferably 900,000 or less, particularly 800,000 from the viewpoint of compatibility with the polymerizable compound component. The following is preferable. The number average molecular weight in the present invention is a value measured by gel permeation chromatography (GPC) and converted to standard polystyrene.

Although there is no restriction | limiting in particular as a polymeric compound, For example, the compound which has an ethylenically unsaturated group in a molecule | numerator can be used. Specific examples include (meth) acrylates, vinylidene halides, vinyl ethers, vinyl pyridines, vinyl phenols, etc. Among these, (meth) acrylates are preferable from the viewpoint of transparency and heat resistance. As the (meth) acrylate, any of monofunctional, bifunctional, and trifunctional can be used. Here, (meth) acrylate means acrylate and methacrylate.
It is also preferable to include a compound having two or more epoxy groups in the molecule. Specifically, bifunctional aromatic glycidyl ethers such as bisphenol A type epoxy resin, tetrabromobisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol AD type epoxy resin, naphthalene type epoxy resin; phenol novolac type epoxy resin, Polyfunctional aromatic glycidyl ether such as cresol novolac type epoxy resin, dicyclopentadiene-phenol type epoxy resin, tetraphenylolethane type epoxy resin; polyethylene glycol type epoxy resin, polypropylene glycol type epoxy resin, neopentyl glycol type epoxy resin, Bifunctional aliphatic glycidyl ether such as hexanediol type epoxy resin; Bifunctional alicyclic glycidyl ether such as hydrogenated bisphenol A type epoxy resin; Polyfunctional aliphatic glycidyl ethers such as roll propane type epoxy resin, sorbitol type epoxy resin, glycerin type epoxy resin; bifunctional aromatic glycidyl esters such as diglycidyl phthalate; tetrahydrophthalic acid diglycidyl ester, hexahydrophthalic acid di Bifunctional alicyclic glycidyl esters such as glycidyl ester; bifunctional aromatic glycidyl amines such as N, N-diglycidylaniline and N, N-diglycidyltrifluoromethylaniline; N, N, N ′, N′-tetra Polyfunctional aromatic glycidylamines such as glycidyl-4,4-diaminodiphenylmethane, 1,3-bis (N, N-glycidylaminomethyl) cyclohexane, N, N, O-triglycidyl-p-aminophenol; Diepoxy acetal, ants Bifunctional alicyclic epoxy resins such as cyclic diepoxy adipate, alicyclic diepoxycarboxylate, vinylcyclohexene dioxide; Bifunctional heterocyclic epoxy resins such as diglycidylhydantoin; Multifunctional heterogeneous such as triglycidyl isocyanurate Cyclic epoxy resins; bifunctional or polyfunctional silicon-containing epoxy resins such as organopolysiloxane type epoxy resins.

These polymerizable compounds usually have a molecular weight of about 100 to 2000, more preferably about 150 to 1000, 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 polymeric compound. In addition, the molecular weight of the polymerizable compound in the present invention can be measured by GPC method or mass spectrometry.
The blending ratio of the base polymer and the polymerizable compound is preferably 10 to 80% by mass of the base polymer with respect to the total amount of these components. It becomes easy to set it as a film form as it is 10 mass% or more. On the other hand, when it is 80% by mass or less, it is easy to adjust the melt viscosity at the time of lamination to a range of 100 to 200 Pa · s, and the reaction of the polymerizable compound proceeds sufficiently. From these viewpoints, the range of 20 to 70% by mass is more preferable.

In the present invention, the melt viscosity of the resin for forming the upper clad layer is prepared by preparing a measurement sample having a film thickness of 200 to 500 μm, sandwiching the sample in parallel with a pair of circular plates having a diameter of 2 cm, It measured with the temperature increase rate of 5 degree-C / min with the elasticity measuring apparatus (TA Instruments company make, ARES-2KSTD). More specifically, the measurement was performed under the conditions of a shear frequency of 1 Hz and a strain of 5% (rotation angle of 9 degrees).
Here, for the measurement sample, for example, in the same manner as in Example 1 described later, a clad layer-forming resin is applied and dried on a support film such as a polyamide film, and then a release PET film or the like is protected. After affixing the film to produce a clad layer forming resin film, the protective film and the support film are peeled off, the clad layer forming resin layer is taken out, and a plurality of clad forming resin layers are overlaid, and a vacuum pressure laminator Using MVLP-500 (manufactured by Meiki Seisakusho Co., Ltd.), it was evacuated to 500 Pa or less, and then pressurized under conditions of pressure 0.4 MPa, temperature 50 ° C., and time 30 seconds. The number of clad forming resin layers to be overlaid was adjusted so that the film thickness after pressurization was in the range of 200 to 500 μm.

  In the second manufacturing method of the present invention, after the clad layer forming resin film 200 is laminated, heat treatment is performed. As conditions for the heat treatment, the temperature is preferably 40 ° C to 200 ° C, more preferably 50 to 100 ° C. When the temperature is 40 ° C. or higher, no bubbles remain between the core layer 3 and the upper cladding layer 9. When the temperature is 200 ° C. or lower, the clad layer forming resin is not cured, and the lower clad and the core are not swollen or peeled off by the residual solvent or the like contained in the upper clad forming resin film. The heat treatment time is preferably 15 to 120 minutes. Within this time range, no bubbles remain and workability is not sacrificed. From these viewpoints, the heat treatment time is more preferably 20 to 60 minutes.

  Thereafter, in both the first and second manufacturing methods, curing is performed in the same manner as described above by light or heating, as in the first step, and the cladding layer forming resin 20 of the cladding layer forming resin film 200 is cured. Then, a fifth step of forming the upper clad layer 9 is performed (FIG. 1G).

Next, the present invention will be described in more detail using examples.
Example 1 (first manufacturing method)
[Production of resin film for clad layer formation]
(A) As a base polymer (binder polymer), 48 parts by mass of phenoxy resin (trade name: Phenotote YP-70, manufactured by Tohto Kasei Co., Ltd., number average molecular weight 43000), (B) As a photopolymerizable compound, alicyclic Diepoxycarboxylate (trade name: KRM-2110, molecular weight: 252, manufactured by Asahi Denka Kogyo Co., Ltd.) 49.6 parts by mass, (C) As a photopolymerization initiator, triphenylsulfonium hexafluoroantimonate salt (trade name: SP-170, manufactured by Asahi Denka Kogyo Co., Ltd.) 2 parts by mass, as a sensitizer, SP-100 (trade name, manufactured by Asahi Denka Kogyo Co., Ltd.) 0.4 parts by mass, and as an organic solvent, 40 parts by mass of propylene glycol monomethyl ether acetate Weigh the part in a wide-mouth plastic bottle and use a mechanical stirrer, shaft and propeller, In the rolling speed 400rpm conditions, was stirred for 6 hours to prepare a resin varnish A for forming a cladding layer. After that, using a polyflon filter (trade name: PF020, manufactured by Advantech Toyo Co., Ltd.) with a pore diameter of 2 μm, the mixture is filtered under pressure at a temperature of 25 ° C. and a pressure of 0.4 MPa, and further the degree of vacuum using a vacuum pump and a bell jar. Degassed under reduced pressure for 15 minutes under the condition of 50 mmHg.
The clad layer-forming resin varnish A obtained above was coated on a corona-treated surface of a polyamide film (trade name: Miktron, manufactured by Toray Industries, Inc., thickness: 12 μm) (Multicoater TM-MC, Inc. It is applied using Hirano Tech Seed, dried at 80 ° C. for 10 minutes, then at 100 ° C. for 10 minutes, and then as a protective film, a release PET film (trade name: Purex A31, Teijin DuPont Films Co., Ltd., thickness: 25 μm) ) Was attached so that the release surface was on the resin side to obtain a resin film for forming a cladding layer. 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 cured film thickness is 25 μm for the lower cladding layer and 80 μm for the upper cladding layer. Adjusted.

[Production of resin film for core layer formation]
(A) As a base polymer (binder polymer), 26 parts by mass of a phenoxy resin (trade name: Phenotote YP-70, manufactured by Tohto Kasei Co., Ltd.), and (B) 9,9-bis [4- (2-acryloyloxyethoxy) phenyl] fluorene (trade name: A-BPEF, Shin-Nakamura Chemical Co., Ltd.) 36 parts by mass, and bisphenol A type epoxy acrylate (trade name: EA-1020, Shin-Nakamura Chemical Co., Ltd.) 36 parts by mass, (C) As a photopolymerization initiator, 1 part by mass of bis (2,4,6-trimethylbenzoyl) phenylphosphine oxide (trade name: Irgacure 819, manufactured by Ciba Specialty Chemicals), and 1- [4- (2-hydroxyethoxy) phenyl] -2-hydroxy-2-methyl-1-propane-1 ON (trade name: Irgacure 2959, manufactured by Ciba Specialty Chemicals) 1 part by mass, core layer formation by the same method and conditions as in the above production example except that 40 parts by mass of propylene glycol monomethyl ether acetate was used as the organic solvent Resin varnish B was prepared. Thereafter, pressure filtration and degassing under reduced pressure were carried out under the same method and conditions as in the above production example.
The core layer-forming resin varnish B obtained above is applied to the 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. After coating and drying, a 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, and a core layer forming resin A film was obtained. In this example, the gap of the coating machine was adjusted so that the film thickness after curing was 50 μm.

[Fabrication of optical waveguide]
A method for manufacturing the optical waveguide will be described below with reference to FIG.
The release PET film (Purex A31), which is a protective film for the resin film for forming the lower clad layer obtained above, is peeled off, and the resin side (supported) is exposed by an ultraviolet exposure machine (EXM-1172, manufactured by Oak Manufacturing Co., Ltd.). The lower clad layer 2 was formed by irradiating ultraviolet rays (wavelength 365 nm) with 1 J / cm ² from the opposite side of the body film and then heat-treating at 80 ° C. for 10 minutes (see FIG. 1A).

  Next, a roll laminator (HLM-1500, manufactured by Hitachi Chemical Technoplant Co., Ltd.) is used on the lower clad layer 2 under the conditions of pressure 0.4 MPa, temperature 50 ° C., laminating speed 0.2 m / min. The layer forming resin film was laminated to form the core layer 30 (see FIG. 1B).

Next, ultraviolet rays (wavelength 365 nm) are irradiated with 0.8 J / cm ² with the above-described ultraviolet exposure machine through a negative photomask 7 having a line width / line spacing of 50 μm / 75 μm, 12 patterns, and a pattern length of 125 mm. (See FIG. 1 (d)), followed by post-exposure heating at 80 ° C. for 5 minutes. 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 = 8/2, mass ratio) (FIG. 1 (e )reference). Then, it wash | cleaned using the washing | cleaning liquid (isopropanol), and heat-dried at 100 degreeC for 10 minute (s).

Next, as an upper clad layer, a vacuum pressurization laminator (manufactured by Meiki Seisakusho, MVLP-500) is used as a flat plate laminator, vacuumed to 500 Pa or less, pressure 0.4 MPa, temperature 100 ° C., pressurization time The resin film for forming a clad layer was laminated under a condition of 30 seconds (see FIG. 1 (f)). The melt viscosity of the upper clad layer forming resin film at a temperature of 100 ° C. was 170 Pa · s. Thereafter, ultraviolet light (wavelength 365 nm) is irradiated on both surfaces in total at 25 J / cm ² , and then heat-treated at 160 ° C. for 1 hour to form a flexible optical waveguide in which the upper clad layer 9 is formed and the support film is disposed outside. It produced (refer FIG.1 (g)). Furthermore, in order to peel the polyamide film, the flexible optical waveguide was treated for 24 hours at 85 ° C./85% in a high temperature and high humidity condition to produce a flexible optical waveguide from which the support film was removed.
The appearance of the flexible optical waveguide thus produced was examined under a microscope with a magnification of 50 times, and it was confirmed that there were no bubbles in contact with the core.
The propagation loss of the produced optical waveguide was determined using a cut-back method using a surface emitting laser (850 nm manufactured by EXFO, FLS-300-01-VCL) as a light source, and Q82214 manufactured by Advantest Co., Ltd. as a light receiving sensor. (Measurement waveguide length 5, 3, 2 cm, incident fiber: GI-50 / 125 multimode fiber (NA = 0.20), output fiber: SI-114 / 125 (NA = 0.22)) 0.05 dB / cm.

Comparative Example 1
In Example 1, a flexible optical waveguide was produced in the same manner as in Example 1 except that the lamination temperature at the time of forming the upper clad was 60 ° C., 65 ° C., 80 ° C., and 90 ° C. The melt viscosities of the resin films for forming the upper cladding layer at temperatures of 60 ° C., 65 ° C., 80 ° C., and 90 ° C. were 1720 Pa · s, 1180 Pa · s, 445 Pa · s, and 260 Pa · s, respectively. In the flexible optical waveguide produced under these conditions, five or more bubbles having a size of 5 μm or more remaining in contact with the core remained.
The propagation loss of the produced optical waveguide was determined using a cut-back method using a surface emitting laser (850 nm manufactured by EXFO, FLS-300-01-VCL) as a light source, and Q82214 manufactured by Advantest Co., Ltd. as a light receiving sensor. (Measurement waveguide length 5, 3, 2 cm, incident fiber: GI-50 / 125 multimode fiber (NA = 0.20), output fiber: SI-114 / 125 (NA = 0.22)) 0.1 dB / cm, indicating that the propagation loss is degraded due to bubbles.

Example 2 (first manufacturing method)
[Production of resin film for clad layer formation]
(A) As a base polymer (binder polymer), 50 parts by mass of a phenoxy resin (trade name: Phenotote YP-70, manufactured by Tohto Kasei Co., Ltd.), (B) As a photopolymerizable compound, an alicyclic diepoxycarboxylate ( Product name: KRM-2110, molecular weight: 252, manufactured by Asahi Denka Kogyo Co., Ltd.) 50 parts by mass, (C) As a photopolymerization initiator, triphenylsulfonium hexafluoroantimonate salt (trade name: SP-170, Asahi Denka Kogyo) Co., Ltd.) 2 parts by weight, 40 parts by weight of propylene glycol monomethyl ether acetate as an organic solvent are weighed in a wide-mouthed plastic bottle, using a mechanical stirrer, shaft and propeller, at a temperature of 25 ° C. and a rotational speed of 400 rpm, The mixture was stirred for a time to prepare a clad layer forming resin varnish C. After that, using a polyflon filter (trade name: PF020, manufactured by Advantech Toyo Co., Ltd.) with a pore diameter of 2 μm, the mixture is filtered under pressure at a temperature of 25 ° C. and a pressure of 0.4 MPa, and further the degree of vacuum using a vacuum pump and a bell jar. Degassed under reduced pressure for 15 minutes under the condition of 50 mmHg.
The clad layer-forming resin varnish C obtained above was coated on a non-treated surface of a PET film (trade name: Cosmo Shine A4100, manufactured by Toyobo Co., Ltd., thickness: 50 μm) (Multicoater TM-MC). , Manufactured by Hirano Tech Seed Co., Ltd., dried at 80 ° C. for 10 minutes, then at 100 ° C. for 10 minutes, and then as a protective film, a release 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 for forming a clad 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 cured film thickness is 30 μm for the lower cladding layer and 60 μm for the upper cladding layer. Adjusted.

[Production of resin film for core layer formation]
A resin varnish B for forming a core layer was prepared in the same manner and under the same conditions as in Example 1. Thereafter, pressure filtration and degassing under reduced pressure were carried out under the same method and conditions as in the above production example.
The core layer-forming resin varnish B obtained above is applied to the 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. After coating and drying, a 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, and a core layer forming resin A film was obtained. In this example, the gap of the coating machine was adjusted so that the film thickness after curing was 40 μm.

[Fabrication of optical waveguide]
A method for manufacturing the optical waveguide will be described below.
A silane coupling agent (manufactured by Toray Dow Corning Co., Ltd. [Z6040]) is applied at 500 rpm / min by spin coating on a silicon substrate 40 (thickness 0.625 mm, with oxide film 1 μm, manufactured by Mitsubishi Materials Corporation). The coating was carried out under conditions of 10 seconds, further 1500 rpm / 30 seconds, and then heated on a hot plate at 120 ° C. for 3 minutes. For spin coating, “1H-D2” manufactured by Mikasa Co., Ltd. was used. Next, the protective film of the clad layer forming resin film produced above is peeled off, and the laminator (manufactured by Hitachi Chemical Technoplant Co., Ltd.) is made so that the resin layer for forming the clad layer is in contact with the silicon substrate subjected to the silane coupling treatment. HLM-1500) was roll-laminated under the conditions of 80 ° C., 0.5 MPa, and feed rate of 0.5 m. Thereafter, ultraviolet rays (wavelength 365 nm) are irradiated at 1 J / cm ² from the resin side (opposite side of the support film) with an ultraviolet exposure machine (EXM-1172, manufactured by Oak Manufacturing Co., Ltd.), and a PET film (support film) After peeling off Cosmo Shine A4100), the lower clad layer 2 was formed by heat treatment at 120 ° C. for 60 minutes (see FIG. 4A).

  Next, a roll laminator (HLM-1500, manufactured by Hitachi Chemical Technoplant Co., Ltd.) is used on the lower clad layer 2 under the conditions of pressure 0.4 MPa, temperature 50 ° C., laminating speed 0.2 m / min. The layer forming resin film was laminated to form the core layer 30 (see FIG. 4B).

Next, ultraviolet rays (wavelength 365 nm) are irradiated with 0.8 J / cm ² with the above-described ultraviolet exposure machine through a negative photomask 7 having a line width / line spacing of 50 μm / 75 μm, 12 patterns, and a pattern length of 125 mm. (See FIG. 4 (c)), followed by post-exposure heating at 80 ° C. for 5 minutes. 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 = 8/2, mass ratio) (FIG. 4 (d )reference). Then, it wash | cleaned using the washing | cleaning liquid (isopropanol), and heat-dried for 60 minutes at 120 degreeC.

Next, a vacuum pressurization laminator (manufactured by Meiki Seisakusho Co., Ltd., MVLP-500) is used as the upper clad layer, and after vacuuming to 500 Pa or less, pressure 0.4 MPa, temperature 100 ° C., pressurization time The resin film for forming a clad layer was laminated under the condition of 30 seconds (see FIG. 4 (e)). The melt viscosity of the resin film for forming the upper cladding layer at a temperature of 100 ° C. was 121 Pa · s. Thereafter, after irradiation with ultraviolet rays (wavelength 365 nm) at 1 J / cm ² , the upper cladding layer 9 was formed by heat treatment at 160 ° C. for 1 hour (see FIG. 4F).
The appearance of the thus produced optical waveguide was examined under a microscope with a magnification of 50 times, and it was confirmed that there were no bubbles in contact with the core.
The propagation loss of the manufactured optical waveguide was measured in the same manner as in Example 1 and found to be 0.05 dB / cm.

Comparative Example 2
In Example 2, a flexible optical waveguide was produced in the same manner as in Example 2 except that the lamination temperature at the time of forming the upper clad was 60 ° C., 70 ° C., 80 ° C., and 90 ° C. The melt viscosities of the upper clad layer forming resin films at temperatures of 60 ° C., 70 ° C., 80 ° C., and 90 ° C. were 1670 Pa · s, 842 Pa · s, 383 Pa · s, and 233 Pa · s, respectively. In the flexible optical waveguide produced under these conditions, five or more bubbles having a size of 5 μm or more remaining in contact with the core remained.
When the propagation loss of the manufactured optical waveguide was measured in the same manner as in Example 1, it was 0.1 dB / cm, and it was found that the propagation loss was degraded due to bubbles.

Example 3 (second manufacturing method)
[Production of resin film for clad layer formation]
(A) As a base polymer (binder polymer), 48 parts by mass of a phenoxy resin (trade name: Phenotote YP-70, manufactured by Tohto Kasei Co., Ltd.), (B) As a photopolymerizable compound, an alicyclic diepoxycarboxylate ( Product name: KRM-2110, molecular weight: 252, manufactured by Asahi Denka Kogyo Co., Ltd.) 49.6 parts by mass, (C) As a photopolymerization initiator, triphenylsulfonium hexafluoroantimonate salt (trade name: SP-170, Asahi 2 parts by mass of Denka Kogyo Co., Ltd., 0.4 parts by mass of SP-100 (trade name, manufactured by Asahi Denka Kogyo Co., Ltd.) as a sensitizer, and 40 parts by mass of propylene glycol monomethyl ether acetate as an organic solvent Weigh in bottle and use mechanical stirrer, shaft and propeller, temperature 25 ° C, rotation speed 400rpm , It stirred for 6 hours to prepare a resin varnish A for forming a cladding layer. After that, using a polyflon filter (trade name: PF020, manufactured by Advantech Toyo Co., Ltd.) with a pore diameter of 2 μm, the mixture is filtered under pressure at a temperature of 25 ° C. and a pressure of 0.4 MPa, and further the degree of vacuum using a vacuum pump and a bell jar. Degassed under reduced pressure for 15 minutes under the condition of 50 mmHg.
The clad layer-forming resin varnish A obtained above was coated on a corona-treated surface of a polyamide film (trade name: Miktron, manufactured by Toray Industries, Inc., thickness: 12 μm) (Multicoater TM-MC, Inc. It is applied using Hirano Tech Seed, dried at 80 ° C. for 10 minutes, then at 100 ° C. for 10 minutes, and then as a protective film, a release PET film (trade name: Purex A31, Teijin DuPont Films Co., Ltd., thickness: 25 μm) ) Was attached so that the release surface was on the resin side to obtain a resin film for forming a cladding layer. 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 cured film thickness is 25 μm for the lower cladding layer and 80 μm for the upper cladding layer. Adjusted.

[Production of resin film for core layer formation]
(A) As a base polymer (binder polymer), 26 parts by mass of a phenoxy resin (trade name: Phenotote YP-70, manufactured by Tohto Kasei Co., Ltd.), and (B) 9,9-bis [4- (2-acryloyloxyethoxy) phenyl] fluorene (trade name: A-BPEF, Shin-Nakamura Chemical Co., Ltd.) 36 parts by mass, and bisphenol A type epoxy acrylate (trade name: EA-1020, Shin-Nakamura Chemical Co., Ltd.) 36 parts by mass, (C) As a photopolymerization initiator, 1 part by mass of bis (2,4,6-trimethylbenzoyl) phenylphosphine oxide (trade name: Irgacure 819, manufactured by Ciba Specialty Chemicals), and 1- [4- (2-hydroxyethoxy) phenyl] -2-hydroxy-2-methyl-1-propane-1 ON (trade name: Irgacure 2959, manufactured by Ciba Specialty Chemicals) 1 part by mass, core layer formation by the same method and conditions as in the above production example except that 40 parts by mass of propylene glycol monomethyl ether acetate was used as the organic solvent Resin varnish B was prepared. Thereafter, pressure filtration and degassing under reduced pressure were carried out under the same method and conditions as in the above production example.
The core layer-forming resin varnish B obtained above is applied to the 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. After coating and drying, a 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, and a core layer forming resin A film was obtained. In this example, the gap of the coating machine was adjusted so that the film thickness after curing was 70 μm.

[Fabrication of optical waveguide]
A method for manufacturing the optical waveguide will be described below with reference to FIG.
The release PET film (Purex A31), which is a protective film for the resin film for forming the lower clad layer obtained above, is peeled off, and the resin side (supported) is exposed by an ultraviolet exposure machine (EXM-1172, manufactured by Oak Manufacturing Co., Ltd.). The lower clad layer 2 was formed by irradiating ultraviolet rays (wavelength 365 nm) with 1 J / cm ² from the opposite side of the body film and then heat-treating at 80 ° C. for 10 minutes (see FIG. 1A).

  Next, a roll laminator (HLM-1500, manufactured by Hitachi Chemical Technoplant Co., Ltd.) is used on the lower clad layer 2 under the conditions of pressure 0.4 MPa, temperature 50 ° C., laminating speed 0.2 m / min. The layer forming resin film was laminated to form the core layer 30 (see FIG. 1B).

Next, ultraviolet rays (wavelength 365 nm) are irradiated with 0.8 J / cm ² with the above-described ultraviolet exposure machine through a negative photomask 7 having a line width / line spacing of 80 μm / 170 μm, 8 patterns, and a pattern length of 125 mm. (See FIG. 1 (d)), followed by post-exposure heating at 80 ° C. for 5 minutes. 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 = 8/2, mass ratio) (FIG. 1 (e )reference). Then, it wash | cleaned using the washing | cleaning liquid (isopropanol), and heat-dried at 100 degreeC for 10 minute (s).

Next, as an upper clad layer, a vacuum pressurizing laminator (manufactured by Meiki Seisakusho Co., Ltd., MVLP-500) is used as a flat plate laminator, vacuumed to 500 Pa or less, pressure 0.4 MPa, temperature 60 ° C., pressurizing time The resin film 1 for forming a clad layer was laminated under a condition of 30 seconds (see FIG. 1 (f)). At this time, when an appearance inspection was performed under a microscope with a magnification of 100, four bubbles were in contact with the core in the upper clad (see FIG. 5).
Subsequently, in order to eliminate the bubbles, heating was performed in a heating furnace at 50 ° C. for 30 minutes, and the appearance was similarly examined under a microscope. As a result, the bubbles disappeared (see FIG. 6).
Thereafter, ultraviolet light (wavelength 365 nm) is irradiated on both surfaces in total at 25 J / cm ² , and then heat-treated at 160 ° C. for 1 hour to form a flexible optical waveguide in which the upper clad layer 9 is formed and the support film is disposed outside. It produced (refer FIG.1 (g)). Furthermore, in order to peel the polyamide film, the flexible optical waveguide was treated for 24 hours at 85 ° C./85% in a high temperature and high humidity condition to produce a flexible optical waveguide from which the support film was removed.
Propagation loss of the produced optical waveguide was measured using a cut-back method (measurement) using a 850 nm surface emitting laser (EXFO, FLS-300-01-VCL) as a light source, and Advantest Co., Ltd., Q82214 as a light receiving sensor. Waveguide length 5, 3, 2 cm, incident fiber: GI-50 / 125 multimode fiber (NA = 0.20), output fiber: SI-114 / 125 (NA = 0.22)) 0.05 dB / cm.
Further, it was confirmed that the bubbles could be eliminated even when the heating temperature after the upper clad lamination was 60 ° C., 70 ° C., 80 ° C., 90 ° C., 100 ° C.

Comparative Example 3
An optical waveguide was produced by the same optical waveguide forming resin film and process as in Example 3 except that the heat treatment after the upper clad lamination was not performed. As a result, bubbles remained after the upper clad lamination remained as it was. The propagation loss of the optical waveguide manufactured under these conditions is 0.1 dB / cm, and it has been found that the propagation loss is deteriorated due to bubbles.

Example 4 (second manufacturing method)
[Production of resin film for clad layer formation]
(A) As a base polymer (binder polymer), 50 parts by mass of a phenoxy resin (trade name: Phenotote YP-70, manufactured by Tohto Kasei Co., Ltd.), (B) As a photopolymerizable compound, an alicyclic diepoxycarboxylate ( Product name: KRM-2110, molecular weight: 252, manufactured by Asahi Denka Kogyo Co., Ltd.) 50 parts by mass, (C) As a photopolymerization initiator, triphenylsulfonium hexafluoroantimonate salt (trade name: SP-170, Asahi Denka Kogyo) Co., Ltd.) 2 parts by weight, 40 parts by weight of propylene glycol monomethyl ether acetate as an organic solvent are weighed in a wide-mouthed plastic bottle, using a mechanical stirrer, shaft and propeller, at a temperature of 25 ° C. and a rotational speed of 400 rpm, The mixture was stirred for a time to prepare a clad layer forming resin varnish C. After that, using a polyflon filter (trade name: PF020, manufactured by Advantech Toyo Co., Ltd.) with a pore diameter of 2 μm, the mixture is filtered under pressure at a temperature of 25 ° C. and a pressure of 0.4 MPa, and further the degree of vacuum using a vacuum pump and a bell jar. Degassed under reduced pressure for 15 minutes under the condition of 50 mmHg.
The clad layer-forming resin varnish C obtained above was coated on an easy-adhesion treated surface of a PET film (trade name: Cosmo Shine A1517, manufactured by Toyobo Co., Ltd., thickness: 16 μm) (Multicoater TM- MC, manufactured by Hirano Tech Seed Co., Ltd., dried at 80 ° C. for 10 minutes, then at 100 ° C. for 10 minutes, and then released as a protective PET film (trade name: Purex A31, Teijin DuPont Film Co., Ltd.) (Thickness: 25 μm) was pasted so that the release surface was on the resin side to obtain a resin film for forming a cladding layer. 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 after curing is 30 μm for the lower cladding layer and 80 μm for the upper cladding layer. Adjusted.

[Production of resin film for core layer formation]
A resin film for forming a core layer was obtained by the same method and conditions as in Example 3. In this example, the gap of the coating machine was adjusted so that the film thickness after curing was 50 μm.

[Fabrication of optical waveguide]
A method for manufacturing the optical waveguide will be described below with reference to FIG.
The release PET film (Purex A31), which is a protective film of the resin film 2 for forming the lower clad layer obtained above, is peeled off, and the resin side (EXM-1172, manufactured by Oak Manufacturing Co., Ltd.) is used on the resin side ( The lower clad layer 2 was formed by irradiating ultraviolet rays (wavelength 365 nm) with 1 J / cm ² from the opposite side of the support film, followed by heat treatment at 80 ° C. for 10 minutes (see FIG. 1A).

  Next, a roll laminator (HLM-1500, manufactured by Hitachi Chemical Technoplant Co., Ltd.) is used on the lower clad layer 2 under the conditions of pressure 0.4 MPa, temperature 50 ° C., laminating speed 0.2 m / min. The layer forming resin film was laminated to form the core layer 30 (see FIG. 1B).

Next, ultraviolet light (wavelength 365 nm) is irradiated with 0.8 J / cm ² with the above-described ultraviolet exposure machine through a negative photomask 7 having a line width / line spacing of 50 μm / 250 μm, 12 patterns, and a pattern length of 125 mm. (See FIG. 1 (d)), followed by post-exposure heating at 80 ° C. for 5 minutes. 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 = 8/2, mass ratio) (FIG. 1 (e )reference). Then, it wash | cleaned using the washing | cleaning liquid (isopropanol), and heat-dried at 100 degreeC for 10 minute (s).

Next, as an upper clad layer, a vacuum pressurizing laminator (manufactured by Meiki Seisakusho Co., Ltd., MVLP-500) is used as a flat plate laminator, vacuumed to 500 Pa or less, pressure 0.4 MPa, temperature 60 ° C., pressurizing time The resin film 1 for forming a clad layer was laminated under a condition of 30 seconds (see FIG. 1 (f)). At this time, when an appearance inspection was performed under a microscope with a magnification of 100, there were three bubbles in the upper clad in contact with the core.
Then, in order to lose | disappear this bubble, it heated in 50 degreeC and the heating furnace for 30 minutes, and the bubble was lose | disappeared.
Thereafter, ultraviolet rays (wavelength 365 nm) are irradiated on both surfaces in total 6 J / cm ² , and then heat-treated at 120 ° C. for 1 hour to form an upper clad layer 9 and a flexible optical waveguide having a support film disposed on the outside. It produced (refer FIG.1 (g)).
Propagation loss of the produced optical waveguide was measured using a cut-back method (measurement) using a 850 nm surface emitting laser (EXFO, FLS-300-01-VCL) as a light source, and Advantest Co., Ltd., Q82214 as a light receiving sensor. Waveguide length 5, 3, 2 cm, incident fiber: GI-50 / 125 multimode fiber (NA = 0.20), output fiber: SI-114 / 125 (NA = 0.22)) 0.05 dB / cm.
Further, it was confirmed that the bubbles could be eliminated even when the heating temperature after the upper clad lamination was 60 ° C., 70 ° C., 80 ° C., 90 ° C., 100 ° C.

Comparative Example 4
An optical waveguide was produced by the same optical waveguide forming resin film and process as in Example 4 except that the heat treatment after the upper clad lamination was not performed. As a result, bubbles remained after the upper clad lamination remained as it was. The propagation loss of the optical waveguide manufactured under these conditions is 0.1 dB / cm, and it has been found that the propagation loss is deteriorated due to bubbles.

Example 5 (second manufacturing method)
In Example 4, except that the support film of the resin film for forming the clad was changed to a PET film having a thickness of 25 μm (trade name: Purex A31, Teijin DuPont Film Co., Ltd., non-treated surface used) An optical waveguide was prepared in the same manner as in 2. At this time, after the upper clad lamination, when an appearance inspection was performed under a microscope with a magnification of 100 times, there were four bubbles in the upper clad in contact with the core. Even in this case, bubbles could be eliminated by setting the heating temperature after the upper clad lamination to 50 ° C., 60 ° C., 70 ° C., 80 ° C., 90 ° C., and 100 ° C.

Comparative Example 5
An optical waveguide was produced by the same optical waveguide forming resin film and process as in Example 5 except that the heat treatment after the upper clad lamination was not performed. As a result, bubbles remained after the upper clad lamination remained as it was.

Example 6 (second manufacturing method)
In Example 3, the support film of the resin film for forming a clad was changed to an aramid film having a thickness of 9 μm (trade name: Mikutron, Toray Industries, Inc., using a corona-treated surface), as in Example 3. An optical waveguide was produced. At this time, after the upper clad laminate, an appearance inspection was performed under a microscope with a magnification of 100. As a result, there was one bubble in contact with the core in the upper clad. In this case, bubbles could be eliminated by setting the heating temperature after the upper clad lamination to 40 ° C. and the heating time to 60 minutes.

Comparative Example 6
An optical waveguide was produced by the same optical waveguide forming resin film and process as in Example 6 except that the heat treatment after the upper clad lamination was not performed. As a result, bubbles remained after the upper clad lamination remained as it was.

The results of Examples 3 to 6 and Comparative Examples 3 to 6 are shown in Table 1.

As described above in detail, according to the manufacturing method of the present invention, the optical waveguide can be manufactured with high productivity, and no bubbles remain between the core layer and the upper cladding layer. In particular, according to the second manufacturing method, the optical waveguide can be manufactured with high productivity, and no bubbles remain between the core layer and the upper cladding layer, and the upper cladding layer is flat.
For this reason, it is extremely useful as a manufacturing method of a highly practical optical waveguide.

Claims (3)

Curing the clad layer forming resin formed on the substrate to form a lower clad layer, laminating a core layer forming resin film on the lower clad layer to form a core layer, the core layer A step of forming a core pattern by exposing and developing the substrate, and laminating a resin film for forming an upper cladding layer on the core pattern, and curing the resin for forming the cladding layer to form an upper cladding layer. A method of manufacturing a waveguide,
A light guide characterized in that, when laminating the resin film for forming the upper clad layer, the laminating conditions are controlled so that the melt viscosity of the resin for forming the clad layer is 120 to 180 Pa · s, and thermocompression bonding is performed in a reduced pressure atmosphere. A method for manufacturing a waveguide.   2. The optical waveguide according to claim 1, wherein the step of forming the core layer includes a step of heat-pressing the resin film for forming the core layer on the lower clad layer using a roll laminator having a heat roll. Manufacturing method.   3. The method of manufacturing an optical waveguide according to claim 1, wherein when laminating the resin film for forming an upper clad layer on the core pattern, thermocompression bonding is performed in a reduced pressure atmosphere using a flat plate laminator.

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