JP5870489B2 - Optical waveguide, photoelectric composite substrate, optical waveguide manufacturing method, and photoelectric composite substrate manufacturing method - Google Patents

Description

  The present invention relates to a method of manufacturing an optical waveguide on a substrate, an optical waveguide manufactured by the manufacturing method, a manufacturing method of an optoelectric composite substrate that manufactures an optical waveguide on an electric wiring board, and a manufacturing method thereof. The present invention relates to a photoelectric composite substrate.

  With the increase in information capacity, development of an 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 composite board in which an optical transmission path is combined with an electric wiring board has been developed. As the optical transmission line, it is desirable to use an optical waveguide with higher wiring flexibility and higher density than optical fiber. Among them, an optical waveguide using a polymer material with excellent workability and economy is promising. It is.

As a method for manufacturing an optical waveguide, for example, in Patent Document 1, after a lower clad layer is cured and formed on a carrier film, a core layer is formed on the lower clad layer, and exposure and development are performed. A build-up method is described in which a core layer is formed and an upper cladding layer is laminated.
However, in this method, since the clad layer is formed on the entire surface of the carrier film, there is a problem that the warpage of the substrate becomes large due to curing shrinkage of the optical waveguide. Further, when the carrier film is an electric wiring board, the electric wiring board on the optical waveguide forming surface side is covered with a clad layer, so that it is difficult to mount an element on the optical waveguide forming surface.
As a method of forming an optical waveguide on a part of a substrate, as described in Patent Document 2, a method of adhering an optical waveguide to the surface of a semiconductor chip using an adhesive layer has been proposed. Specifically, in Patent Document 2, after forming an optical waveguide on a dummy substrate, the optical waveguide is peeled off from the dummy substrate (individualization step) and bonded to a semiconductor chip via an adhesive (adhesion step). However, this method requires a step of dividing the optical waveguide and is complicated. Further, in the individualizing step and the adhering step, it is difficult to align with high accuracy.

JP2003-195081 JP 2006-39390 A

  The present invention has been made to solve the above-described problems, and can form an optical waveguide on a part of the substrate with high alignment accuracy, and since the optical waveguide is formed on a part of the substrate, there is little warping of the substrate. To provide an optical waveguide manufacturing method, an optoelectric composite substrate manufacturing method, an optical waveguide manufactured by such a manufacturing method, and an optoelectric composite substrate capable of mounting an element on a portion where no optical waveguide is formed. Objective.

The present invention provides the following (1) to (13).
(1) An optical waveguide manufacturing method in which an optical waveguide having a lower clad pattern and a core pattern is laminated on a part of the surface of a substrate, wherein a lower clad layer forming resin is laminated on the upper surface of the substrate After forming the clad layer, a first step of patterning the lower clad layer to expose a part of the surface of the substrate to form a lower clad pattern, and a core layer on the lower clad pattern and on the substrate A method for manufacturing an optical waveguide, comprising: a second step of sequentially forming a core layer by forming a core layer by laminating a forming resin, and then forming a core pattern only on the lower cladding pattern.
(2) In the second step, after laminating the core layer forming resin on the lower clad pattern and on the substrate, the core layer forming resin is planarized to form the core layer, The method for manufacturing an optical waveguide according to (1), wherein the total thickness of the lower clad pattern and the core layer formed on the lower clad pattern and the thickness of the core layer formed on the substrate are made constant.
(3) The core layer forming resin comprises a core layer forming resin film, and the thickness of the core layer forming resin film is greater than the thickness of the core pattern, and the thickness of the lower cladding pattern and the core pattern The method for manufacturing an optical waveguide according to claim 1 or 2, wherein the thickness is equal to or less than a total thickness.
(4) The lower clad pattern has a rectangular parallelepiped shape, the core pattern extends in parallel with a pair of side surfaces of the lower clad pattern, and the lower clad pattern is orthogonal to the extending direction of the core pattern. The width of the direction is 40 mm or less, and the core pattern is located on the inner side of the pair of side surfaces of the lower cladding pattern by 0.1 μm or more in the width direction among the surfaces of the lower cladding pattern (3 The manufacturing method of the optical waveguide as described in).
(5) The method for manufacturing an optical waveguide according to any one of (1) to (4), wherein the number of the core patterns formed on the lower cladding pattern is three or more.
(6) The method for manufacturing an optical waveguide according to any one of (1) to (5), wherein an area obtained by removing the lower cladding layer in the first step is larger than an area of the lower cladding pattern.
(7) After the second step, after forming the upper clad layer by laminating the core pattern, the lower clad pattern, and the upper clad layer forming resin from the upper surface side of the substrate, The optical waveguide according to any one of (1) to (6), further including a third step of patterning the upper clad layer so that a portion is exposed and forming an upper clad pattern on the lower clad pattern and the core pattern. Manufacturing method.
(8) The upper clad layer forming resin is an upper clad layer forming resin film, and the upper clad layer forming resin film has a thickness of the lower clad pattern and a core pattern formed on the lower clad pattern. (7) The method for manufacturing an optical waveguide according to (7), wherein the total thickness is equal to or greater than the total thickness.
(9) In the third step, after the upper clad layer forming resin is laminated, the upper clad layer forming resin is flattened to form the upper clad layer, whereby the lower clad pattern and the lower clad layer are formed. The total thickness of the core pattern formed on the pattern, the upper cladding layer formed on the core pattern, and the thickness of the upper cladding layer formed on the substrate are made constant (7) or (8 The manufacturing method of the optical waveguide as described in).
(10) An optical waveguide formed by any one of the methods (1) to (9).
(11) A method of manufacturing an opto-electric composite board having an electric wiring board and an optical waveguide formed on a part of the surface of the electric wiring board, wherein the electric wiring board is used as the substrate. A method for producing an opto-electric composite substrate, wherein an optical waveguide is produced on a part of the surface of the optical waveguide by the method for producing an optical waveguide according to (1) to (10).
(12) The method for manufacturing an optoelectric composite substrate according to (11), wherein the electric wiring board has an electric wiring pattern on a surface on a side where the optical waveguide is formed.
(13) A photoelectric composite substrate manufactured by the method of (11) or (12).

  According to the present invention, an optical waveguide can be formed on a portion of the substrate with high alignment accuracy, and since the optical waveguide is formed on a portion of the substrate, there is little warpage of the substrate, and element mounting is performed on the portion of the substrate where the optical waveguide is not formed. An optical waveguide manufacturing method, an optoelectric composite substrate manufacturing method, an optical waveguide and an optoelectric composite substrate manufactured by the manufacturing method can be provided.

It is sectional drawing explaining the manufacturing method of the optical waveguide and photoelectric composite substrate which concern on embodiment. FIG. 2 is a plan view of FIG.

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a cross-sectional view for explaining a method of manufacturing an optical waveguide and a photoelectric composite substrate according to the embodiment, and FIG. 2 is a plan view of FIG.
In this embodiment, when it is expressed as a clad layer forming resin or a core layer forming resin, it indicates a resin or a resin film before lamination, and when it is expressed as a clad layer or a core layer, it is on the substrate. Refers to the state after laminating the clad layer forming resin or the core layer forming resin. When noting the clad pattern or core pattern, the clad layer or core layer is partially removed, and the patterned state is I will point.
Although the details will be described later, the method of manufacturing the optical waveguide according to the present embodiment manufactures the optical waveguide 5 in which the optical waveguide 5 having the lower clad pattern 201 and the core pattern 301 is laminated on a part of the surface of the substrate 1. A method of forming a lower clad layer 2 by laminating a resin for forming a lower clad layer on an upper surface of the substrate 1, and then patterning the lower clad layer 2 so that a part of the surface of the substrate 1 is exposed. And forming a lower clad pattern 201 (FIGS. 1C to 1D), a core layer forming resin is laminated on the lower clad pattern 201 and the substrate 1 to form the core layer 3. After the formation, the second step (FIGS. 1E to 1F) of forming the core pattern 301 only on the lower clad pattern 201 by patterning the core layer 3 is sequentially provided.
In the following, these first and second steps, a step of forming an electric wiring pattern on the substrate surface before these steps to form an electric wiring board (an electric wiring board manufacturing process), a second step, The process of manufacturing the upper cladding pattern after the process (upper cladding pattern manufacturing process) will be described in detail.

<Electrical wiring board manufacturing process (FIGS. 1A to 1B)>
In the present embodiment, as the substrate 1, an electric wiring board in which an electric wiring pattern 103 is formed on the upper surface and the lower surface of the substrate body 101 is used.
There is no particular limitation on the method of manufacturing the substrate (electrical wiring board) 1. For example, a laminated material having a metal layer 102 on the entire upper and lower surfaces of the substrate body 101 is prepared (FIG. 1A). The substrate (electric wiring board) 1 can be manufactured by patterning the layer 102 by etching or the like to manufacture the metal wiring pattern 103 (FIG. 1B).
The material of the substrate body 101 is not particularly limited. For example, a glass epoxy resin substrate, a ceramic substrate, a glass substrate, a silicon substrate, a plastic substrate, a metal substrate, a substrate with a resin layer, a substrate with a metal layer, a plastic film, a resin layer And a plastic film with a metal layer and a plastic film with a metal layer.

  Substrate main body 101 having flexibility and toughness, for example, polyester such as polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polyethylene, polypropylene, polyamide, polycarbonate, polyphenylene ether, polyether sulfide, polyarylate, liquid crystal polymer , Polysulfone, polyethersulfone, polyetheretherketone, polyetherimide, polyamideimide, and polyimide may be used for flexibility.

  Although the thickness of the board | substrate 1 may be suitably changed with the curvature of a board and dimensional stability, Preferably it is 0.1-10.0 mm. When the optical signal whose optical path has been changed passes through the substrate 1, it is preferable to use the substrate 1 that is transparent to the wavelength of the optical signal.

  In the present embodiment, a plurality (four) of metal wiring patterns 103 extending in the short side direction are provided on the upper surface of the substrate body 101 at intervals in the long side direction of the substrate (see FIG. 2). ). Similarly, a plurality of (four) metal wiring patterns 103 are also provided on the lower surface of the substrate body 101. The thickness of the electric wiring pattern 103 is preferably 3 to 18 μm. If the thickness of the electric wiring pattern 103 is equal to or greater than the lower limit of this range, the electric wiring pattern 103 can be easily formed and the electric resistance is reduced. When the thickness of the electrical wiring pattern 103 is equal to or less than the upper limit of this range, formation of the lower cladding layer 2, the core layer 3, and the upper cladding layer 4 described later on the electrical wiring pattern 103 is facilitated.

<First Step (FIGS. 1C to 1D)>
In this step, after the lower clad layer forming resin is laminated on the upper surface of the substrate 1 to form the lower clad layer 2 (FIG. 1C), the lower portion is exposed so that a part of the surface of the substrate 1 is exposed. The cladding layer 2 is patterned to form a lower cladding pattern 201 (FIG. 1D).

(Formation method of lower clad layer (FIG. 1C))
The method for forming the lower clad layer 2 is not particularly limited. For example, a lower clad layer forming resin may be applied to the upper surface of the substrate 1, and a film made of the lower clad layer forming resin is applied to the upper surface of the substrate 1. May be laminated.
In the case of application, the method is not limited. For example, a resin composition described later may be applied by a conventional method.
Moreover, the resin film for lower clad layer formation used for a lamination can be easily manufactured, for example by apply | coating what melt | dissolved this resin composition in the solvent to a support body film, and removing a solvent.

The resin film for forming the lower clad layer is preferably formed on a support film and peeled off from the support film. Examples of the supporting film include, for example, polyesters such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate, polyethylene, polypropylene, polyamide, polycarbonate, polyphenylene ether, polyether sulfide, polyarylate, liquid crystal polymer, polysulfone, polyethersulfone, Preferred examples include polyether ether ketone, polyether imide, polyamide imide, and polyimide. The thickness of the support film is preferably 5 to 200 μm. When it is 5 μm or more, there is an advantage that the strength as a support film is easily obtained, and when it is 200 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 is more preferably in the range of 10 to 100 μm, and particularly preferably 15 to 50 μm.
A core layer forming resin film and an upper clad layer forming resin film, which will be described later, are also preferably formed on a support film similar to the above.

(Formation method of lower clad pattern (FIG. 1 (d))
The method of forming the lower cladding pattern 201 from the lower cladding layer 2 is not particularly limited. For example, the lower cladding layer 2 may be formed by etching. When the photosensitive lower cladding layer 2 is used, exposure and exposure are performed. By developing, the lower clad pattern 201 can be formed.

In the present embodiment, the lower cladding pattern 201 is formed so that the entire electric wiring pattern 103 is exposed.
The lower cladding pattern 201 has a rectangular parallelepiped shape extending in the long side direction of the substrate main body 101, and both ends thereof extend to a pair of short sides of the substrate main body 101. The lower clad pattern 201 is preferably formed at a position separated from the electric wiring pattern 103.

The width L in the direction orthogonal to the extending direction of the lower cladding pattern 201 (that is, the direction orthogonal to the extending direction of the core pattern described later) is preferably 40 mm or less. If the width L is 40 mm or less, the area of the surface of the substrate 1 where the lower cladding pattern 201 is formed is reduced, and the warpage of the substrate 1 is reduced. Further, when the width L is 40 mm or less, when the core layer 3 is formed by laminating the resin film for forming the core layer on the lower clad pattern 201 as described later, the lower clad pattern 201 is formed as the core layer. It is possible to easily bite into the resin film, and thereby the upper surface of the core layer 3 can be easily flattened (that is, the total thickness of the lower clad pattern 201 and the core layer 3 thereon and the substrate body). The thickness of the core layer 3 formed on the substrate 101 can be easily made constant). The width L is preferably wider than the core pattern width by 0.1 μm or more on the left and right. When the width L is 0.1 μm or more wider than the core pattern width on the left and right, the core pattern 301 described later can be easily formed on the lower cladding pattern 201. From these viewpoints, the width L is more preferably 5 μm to 3.5 mm, and further preferably 5 μm to 1.0 mm.
The area of the lower cladding pattern 201 is preferably ½ or less of the area of the substrate 1. When there are a plurality of core patterns, a plurality of core patterns may be formed on one lower cladding pattern within the above range. Thereby, the curvature of the board | substrate 1 can be reduced favorably. The area of the lower clad pattern 201 is more preferably 1/3 or less of the area of the substrate 1, and further preferably 1/4 or less.

  The thickness of the lower cladding pattern 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 lower cladding pattern is more preferably in the range of 10 to 100 μm.

(Resin composition)
The resin for forming the lower cladding layer is not particularly limited as long as it is a resin composition that has a lower refractive index than the core pattern 301 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 preferably composed of a resin composition containing (A) a base polymer, (B) a photopolymerizable compound, and (C) a photopolymerization initiator.

  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 a constituent unit of the copolymer component 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 It is. 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.
As a blending amount of the component (A) and the component (B), when 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 85% by mass of the component (A) and 90 to 15% by mass of the component (B), and 20 to 70 of the component (A). More preferably, the content is 80% by mass and the component (B) is 80 to 30% by mass.
(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 absorption in the surface layer of the photosensitive resin composition does not increase during exposure, and the internal Is sufficiently cured. Furthermore, when used as an optical waveguide, it is preferable that the light 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.

<Second Step (FIGS. 1E to 1F)>
In this step, after forming the core layer 3 by laminating the core layer forming resin on the lower clad pattern 201 and the substrate 1 (FIG. 1E), the core layer 3 is patterned, The core pattern 301 is formed only on the lower clad pattern 201 (FIG. 1 (f)).

(Method for forming core layer (FIG. 1 (e))
The method for forming the core layer 3 is not particularly limited. For example, a core layer forming resin may be applied to the upper surfaces of the substrate 1 and the lower cladding pattern 201, and a film made of the core layer forming resin may be applied to the substrate 1. And it may be laminated on the upper surface of the lower cladding pattern 201.
In the case of application, the method is not limited. For example, the resin composition may be applied by a conventional method.
Moreover, the resin film for core layer formation used for a lamination can be easily manufactured by apply | coating what melt | dissolved the resin composition in the solvent to a support body film, and removing a solvent, for example.

In this step, after the core layer forming resin is laminated on the lower clad pattern 201 and the substrate 1, the core layer forming resin is flattened to form the core layer 3. Thus, the total thickness of the lower clad pattern 201 and the core layer 3 formed on the lower clad pattern 201 and the thickness of the core layer 3 formed on the substrate 1 are preferably made constant.
The method for flattening the core layer 3 is not particularly limited, and for example, a method in which pressure lamination is performed with a rigid plate from the opposite side of the core layer to the substrate 1 is preferable. As a method for pressurization, a pressure press or a vacuum laminator may be used. As the rigid plate, various metal plates such as a SUS plate and an Al plate, a copper-clad laminate, a glass plate, a silicon substrate, and the like may be used. As a standard for planarization, the difference between the thickness of the core layer 3 on the substrate 1 and the total thickness of the lower cladding pattern 201 formed on the substrate 1 and the core layer 3 on the lower cladding pattern 201 is 15 μm or less. Considered constant. By doing so, the thickness of the core layer 3 can be easily controlled, the core pattern 3 can be easily formed, and the desired thickness of the core pattern 3 formed on the lower cladding pattern 201 can be easily obtained.

Thickness of Core Layer Forming Film When the core layer 3 is formed using a core layer forming resin film, the thickness of the core layer forming resin film is larger than the thickness of the core pattern 301, The thickness is preferably equal to or less than the total thickness of the cladding pattern 201 and the core pattern 301. When the thickness of the resin film for forming the core layer is equal to or greater than the thickness of the core pattern 301, when the upper surface of the core layer 3 is flattened by the above-described flattening method of the core layer, FIG. Thus, the lower clad pattern 201 can be buried with the core layer 3, and the height of the entire upper surface of the core layer 3 can be easily made the same. Further, when the thickness of the core layer forming resin film is equal to or less than the total thickness of the lower clad pattern 201 and the core pattern 301, the core layer forming film is discarded without being the core layer 3. Is reduced.

Theoretically, in order to use the core layer forming resin film without waste, the thickness of the core layer forming resin film is set so that the volume of the core layer forming resin film is the same as the volume of the core layer 3. Just decide. The volume of the core layer 3 can be calculated by the following formula.
Volume of core layer 3 = (height from the upper surface of substrate 1 to the upper surface of core layer 3) × area of substrate 1
-Volume of the lower cladding pattern 201
-Total volume of the electrical wiring pattern 103
-The total volume of the convex part arrange | positioned on the other board | substrate 1
+ Total volume of the recesses arranged on the other substrate 1
= Thickness of core layer 3 x area of substrate 1
-Total area x thickness of the lower cladding pattern 201
-Total area x thickness of electrical wiring pattern 103
-The total volume of the convex part arrange | positioned on the other board | substrate 1
+ Other by the total volume of the recess disposed on the substrate 1, the optimum thickness d _c of the theoretical resin film for forming a core layer can be calculated by the following equation.
d _c = volume of core layer 3 / area of substrate 1 = {thickness of core layer 3 × area of substrate 1
-Total area x thickness of the lower cladding pattern 201
-Total area x thickness of electrical wiring pattern 103
-The total volume of the convex part arrange | positioned on the other board | substrate 1
+ Other total volume of recesses arranged on the substrate 1 / area of the substrate 1 However, actually, the present invention is not limited to the above formula (the thickness d _{c of} the core layer forming resin film calculated by the above formula ₎ −15 μm) to (the thickness d _{c of} the core layer forming resin film calculated by the above formula +5 μm) When the core layer forming resin appropriately adjusted is used, the desired thickness of the core pattern 301 is easily obtained. be able to.

  When the substrate area from which the lower clad layer 2 is removed is larger than the area of the lower clad pattern 201, the resin having the same thickness as the core pattern 301 desired by the core layer forming resin is used. It becomes extremely difficult to obtain a desired thickness of the core pattern 301. The reason is that the core layer forming resin flows to the portion where the lower cladding layer 2 is removed, and the thickness of the core layer forming resin on the lower cladding pattern 201 is larger than the thickness of the core layer forming resin to be used. This is because the thin film is formed. Therefore, in this case, in particular, as described above, the thickness of the resin film for forming the core layer is larger than the thickness of the core pattern 301, and is equal to or less than the total thickness of the thickness of the lower cladding pattern 201 and the thickness of the core pattern 301. Preferably there is.

(Method for forming core pattern (FIG. 1 (f))
In the present invention, the method for forming the core pattern 301 is not particularly limited. For example, the core layer 3 is formed by coating a core layer forming resin or laminating a core layer forming resin film, and the core pattern 301 is formed by etching. Just do it.
The core layer forming resin used for the core layer 3 is designed to have a higher refractive index than the upper cladding layer 2 and the upper cladding layer 4 described later. The resin for forming the core layer is not limited, and examples thereof include the same resin composition as that of the lower clad layer 2.

Shape of Core Pattern In the present embodiment, a plurality (three) of core patterns 301 are formed on the lower clad pattern 201. These core patterns 301 have a rectangular parallelepiped shape extending in the long side direction of the substrate body 101, and both ends thereof extend to a pair of short sides of the substrate body 101. These core patterns 301 are arranged in parallel with a gap in the short direction of the lower clad pattern 201 (the short side direction of the substrate 1).
The core pattern 301 is in the width L direction of FIG. 1D than the pair of side surfaces (a pair of long side surfaces facing the short side direction of the substrate 1) of the lower clad pattern 201 on the surface of the lower clad pattern 201. It is preferable that it is located inside 0.1 μm or more. That is, in FIG. 1F, the distance a between the left side surface of the lower cladding pattern 201 and the left side surface of the core pattern 301 on the left end side is 0.1 μm or more, and the right side surface and the right end side of the lower cladding pattern 201 are The distance b from the right side surface of the core pattern 301 is preferably 0.1 μm or more. As a result, the upper clad pattern 401 can be satisfactorily formed on the left side of the left end core pattern 301 and the right side of the right core pattern 301, as shown in 1 (h) described later. The light loss of 301 is reduced. Further, even if a defect portion is generated in the vicinity of the left and right side surfaces of the upper surface of the lower clad pattern 201 in FIG. 1 (f), the core pattern 301 can be formed inside the defect portion. A reduction in the dimensional accuracy of is prevented. These distances a and b are more preferably 5 μm or more, and further preferably 20 μm or more.
It is preferable that a gap of 0.1 μm or more is provided between the core patterns 301 as well as the distances a and b. Thereby, as shown in FIG. 1H described later, the upper clad pattern 401 can be satisfactorily formed between the adjacent core patterns, and the optical loss of the core pattern 301 is reduced. The gap between the core patterns 301 is more preferably 50 μm or more, and even more preferably 75 μm or more.

The thickness of the core pattern The thickness of the core pattern 301 existing on the lower cladding pattern 201 (that is, the distance from the upper surface of the lower cladding pattern 201 to the upper surface of the core pattern 301) is not particularly limited, and is usually 10 to 100 μm. It is adjusted to become. When the thickness of the core pattern 301 is 10 μm or more, the film thickness of the core-forming resin film can be easily controlled, coupled with an optical signal from the light emitting element after the optical waveguide is formed, or introduced from an optical fiber. There is an advantage that the alignment tolerance with the optical signal can be expanded, and the coupling can be performed efficiently. When the thickness of the core pattern 301 is 100 μm or less, the film thickness of the core-forming resin film can be easily controlled, coupled with the optical signal from the light receiving element after the optical waveguide is formed, or introduced into the optical fiber. There is an advantage that the alignment tolerance with the optical signal can be expanded, and the coupling can be performed efficiently. From the above viewpoint, the thickness of the core pattern 301 is preferably in the range of 30 to 70 μm.

<Third Step (FIGS. 1 (g) to (h))>
In this step, after the second step, the upper clad layer 4 is formed by laminating the core pattern 301, the lower clad pattern 201, and the upper clad layer forming resin from the upper surface side of the substrate 1 (see FIG. 1 (g)), the upper clad layer 4 is patterned so that a part of the surface of the substrate 1 is exposed, and an upper clad pattern 401 is formed on the lower clad pattern 201 and the core pattern 301 (see FIG. FIG. 1 (h)).

(Method for forming upper clad layer (FIG. 1 (g))
The method for forming the upper clad layer is not particularly limited. For example, an upper clad layer forming resin may be applied to the upper surfaces of the substrate 1, the lower clad pattern 201, and the core pattern 301, and laminated on these upper surfaces. May be.
The method of application and lamination is not limited, and application and lamination may be performed in the same manner as in the case of the lower clad layer 2 described above.
The resin composition used for the upper clad layer forming resin is not particularly limited as long as it is a resin composition having a lower refractive index than the core pattern 301 and is cured by light or heat. The resin composition is used for the lower clad layer forming resin described above. A thermosetting resin composition and a photosensitive resin composition similar to the resin composition can be suitably used. The resin composition used for the upper clad forming resin may have the same or different content and the same refractive index as the resin composition used for the lower clad layer forming resin described above. Or different.

In this step, after the upper clad layer forming resin is laminated, the upper clad layer forming resin is flattened to form the upper clad layer 4, thereby forming the lower clad pattern 201. And the total thickness of the core pattern 301 formed on the lower clad pattern 201 and the upper clad layer 4 formed on the core pattern 301 and the thickness of the upper clad layer 4 formed on the substrate 1 are constant. It is preferable to make it.
The method for planarizing the upper cladding layer 4 is not particularly limited, and examples thereof include the same method as the planarization method for the core layer 3 described above. As a standard for planarization, the thickness of the upper clad layer 4 on the substrate 1, the lower clad pattern 201 formed on the substrate 1, the core pattern 301 on the lower clad pattern 201, and the core pattern 301 are laminated on the core pattern 301. The difference in total thickness with the upper cladding layer 4 is considered to be 15 μm or less. This facilitates control of the thickness of the upper cladding layer 4, facilitates formation of the upper cladding pattern 401, and facilitates obtaining a desired thickness of the upper cladding pattern 401 formed on the core pattern 301.

Thickness of Upper Cladding Layer Forming Film When the upper clad layer 4 is formed using the upper clad layer forming resin film, the thickness of the upper clad layer forming resin film is equal to the lower clad pattern 201 and the core. It is preferably thicker than the total thickness of the pattern 301, and preferably less than or equal to the total thickness of the lower cladding pattern 201, the core pattern 301, and the upper cladding pattern 401. When the thickness of the upper clad layer forming resin film is larger than the total thickness of the lower clad pattern 201 and the core pattern 301 in this way, the upper surface of the upper clad layer 4 is flattened by the above flattening method of the upper clad layer. 1G, the lower clad pattern 201 and the core pattern 301 can be buried in the upper clad layer 4, and the height of the entire upper surface of the upper clad layer 4 can be easily made the same. Can do. Further, when the thickness of the resin film for forming the upper cladding layer is equal to or less than the total thickness of the thickness of the lower cladding pattern 201, the core pattern 301, and the upper cladding pattern 401, the upper cladding layer of the upper cladding layer forming film. The amount discarded instead of 4 is reduced.

Theoretically, in order to use the upper clad layer forming resin film without waste, the upper clad layer forming resin is set so that the volume of the upper clad layer forming resin film is the same as the volume of the upper clad layer 4. What is necessary is just to determine the thickness of a film. Further, the volume of the upper cladding layer 4 can be calculated by the following equation.
Volume of upper cladding layer 4
= (Height from the upper surface of the substrate 1 to the upper surface of the upper cladding layer 4) × the area of the substrate 1
-Volume of the core pattern 301
-Volume of the lower cladding pattern 201
-Total volume of the electrical wiring pattern 103
-The total volume of the convex part arrange | positioned on the other board | substrate 1
+ Total volume of the recesses arranged on the other substrate 1
= Thickness of upper cladding layer 4 × area of substrate 1
-Total area of core pattern 301 x thickness
-Total area x thickness of the lower cladding pattern 201
-Total area x thickness of electrical wiring pattern 103
-The total volume of the convex part arrange | positioned on the other board | substrate 1
+ Other by the total volume of the recess disposed on the substrate 1, the optimum thickness d _u theoretical upper cladding layer-forming resin film can be calculated by the following equation.
d _u = volume of upper cladding layer 4 / area of substrate 1 = {thickness of upper cladding layer 4 × area of substrate 1
-Total area of core pattern 301 x thickness
-Total area x thickness of the lower cladding pattern 201
-Total area x thickness of electrical wiring pattern 103
-The total volume of the convex part arrange | positioned on the other board | substrate 1
+ Other total volume of recesses arranged on the substrate 1 / area of the substrate 1 However, the present invention is not limited to the above formula, and the thickness d of the resin film for forming the upper cladding layer calculated by the above formula _u −15 μm) to (thickness d _u +5 μm of the upper clad layer forming resin film calculated by the above formula), when the upper clad layer forming resin appropriately adjusted is used, the desired thickness of the upper clad pattern 401 is obtained. Can be easily obtained.

By the above method, an optical waveguide can be manufactured on a part of the surface of the substrate 1. In the present embodiment, since the substrate 1 having the substrate body 101 formed with the electrical wiring pattern 103 is used as the substrate 1, the photoelectric composite substrate is formed by the substrate 1 and the optical waveguide on the substrate 1. Is configured.
As shown in FIG. 1 (h), the optical waveguide 5 is formed only on a part of the surface of the substrate 1, so that the remaining portion of the surface of the substrate 1 can be exposed and the electrical wiring pattern 103 is exposed. Is obtained.

<Other embodiments>
The above embodiment is an example of the present invention, and the present invention is not limited to the above embodiment.
For example, in the present embodiment, the number of core patterns 301 is three, but may be one or two, or may be four or more.

EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to a following example, unless the summary is exceeded.
In Examples and Comparative Examples, various films and substrates used for the production of optical waveguides were produced by the following methods.

[Preparation of resin film for forming clad layer]
(1) Production of (A) base polymer; (meth) acrylic polymer (A-1) 46 mass of propylene glycol monomethyl ether acetate in a flask equipped with a stirrer, cooling tube, gas introduction tube, dropping funnel and thermometer And 23 parts by mass of methyl lactate were weighed and stirred while introducing nitrogen gas. The liquid temperature was raised to 65 ° C., 47 parts by weight of methyl methacrylate, 33 parts by weight of butyl acrylate, 16 parts by weight of 2-hydroxyethyl methacrylate, 14 parts by weight of methacrylic acid, 2,2′-azobis (2,4-dimethylvaleronitrile ) A mixture of 3 parts by mass, 46 parts by mass of propylene glycol monomethyl ether acetate and 23 parts by mass of methyl lactate was added dropwise over 3 hours, followed by stirring at 65 ° C. for 3 hours, and further stirring at 95 ° C. for 1 hour. A (meth) acrylic polymer (A-1) solution (solid content: 45% by mass) was obtained.

(2) Measurement of weight average molecular weight GPC (“SD-8022”, “DP-8020”, and “RI-8020” manufactured by Tosoh Corporation)) is used as the weight average molecular weight (converted to standard polystyrene) of (A-1). It was 3.9 * 10 < ⁴ > as a result of using and measuring. The column used was “Gelpack GL-A150-S” and “Gelpack GL-A160-S” manufactured by Hitachi Chemical Co., Ltd.

(3) Measurement of acid value As a result of measuring the acid value of A-1, it was 79 mgKOH / g. In addition, the acid value was computed from the amount of 0.1 mol / L potassium hydroxide aqueous solution required for neutralizing A-1 solution. At this time, the point at which the phenolphthalein added as an indicator changed color from colorless to pink was defined as the neutralization point.

(4) Preparation of Cladding Layer Forming Resin Varnish (A) As a base polymer, 84 parts by mass of the A-1 solution (solid content 45 mass%) (solid content 38 mass parts), (B) As a photocuring component, polyester 33 parts by mass of urethane (meth) acrylate having a skeleton ("U-200AX" manufactured by Shin-Nakamura Chemical Co., Ltd.) and urethane (meth) acrylate having a polypropylene glycol skeleton ("UA-" manufactured by Shin-Nakamura Chemical Co., Ltd.) 4200 "), 15 parts by mass, (C) polyfunctional block isocyanate solution in which isocyanurate type trimer of hexamethylene diisocyanate is protected with methyl ethyl ketone oxime as a thermosetting component (solid content 75% by mass) (Suika Bayer Urethane Co., Ltd.) ) “Sumijoule BL3175”) 20 parts by mass, (D) As a photopolymerization initiator, 1- [4- (2-hydroxyethoxy) phenyl] -2-hydroxy-2-methyl-1-propan-1-one (“Irgacure 2959” manufactured by Ciba Japan Co., Ltd.), 1 part by weight, bis (2,4,6-trimethyl) 1 part by mass of benzoyl) phenylphosphine oxide (“Irgacure 819” manufactured by Ciba Japan Co., Ltd.) and 23 parts by mass of propylene glycol monomethyl ether acetate as an organic solvent for dilution were mixed with stirring. After pressure filtration using a polyflon filter having a pore size of 2 μm (“PF020” manufactured by Advantech Toyo Co., Ltd.), degassing was performed under reduced pressure to obtain a resin varnish for forming a cladding layer.

(5) Film formation of a resin varnish for forming a clad layer The resin varnish for forming a clad layer obtained above is formed on a non-treated surface of a PET film (“Cosmo Shine A4100” manufactured by Toyobo Co., Ltd., thickness 50 μm). After applying using the coating machine and drying at 100 ° C. for 20 minutes, a surface release treatment PET film (“Purex A31” manufactured by Teijin DuPont Films Co., Ltd., thickness 25 μm) is pasted as a protective film, and various thicknesses are applied. A resin film for forming a cladding layer was obtained.

[Preparation of resin film for core layer formation]
(A) As a base polymer, 26 parts by mass of phenoxy resin (trade name: Phenototo YP-70, manufactured by Toto Kasei Co., Ltd.), (B) 9,9-bis [4- (2-acryloyl) as a photopolymerizable compound Oxyethoxy) 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 mass Parts, (C) 1 part by mass of bis (2,4,6-trimethylbenzoyl) phenylphosphine oxide (trade name: Irgacure 819, manufactured by Ciba Specialty Chemicals) as a photopolymerization initiator, and 1- [4 -(2-Hydroxyethoxy) phenyl] -2-hydroxy-2-methyl-1-propan-1-one (trade name: yl (Cure 2959, manufactured by Ciba Specialty Chemicals Co., Ltd.) 1 part by mass, and using the same method and conditions as in the above production example of the resin varnish for forming a clad layer except that 40 parts by mass of propylene glycol monomethyl ether acetate was used as the organic solvent Layer forming resin varnish B was prepared.
The core layer-forming resin varnish B obtained above is applied onto the non-treated surface of a PET film (trade name: Cosmo Shine A1517, manufactured by Toyobo Co., Ltd., thickness: 16 μm) using the coating machine. After drying at 100 ° C. for 20 minutes, a surface release treatment PET film (“Purex A31” manufactured by Teijin DuPont Films Ltd., thickness 25 μm) is pasted as a protective film to obtain resin films for forming a core layer having various thicknesses. It was.

[Production of substrate]
(1) Electric wiring formation by subtractive method)
Polyimide film 101 with 100 mm square double-sided copper foil as metal layer 102 ((Polyimide; Upilex VT (manufactured by Ube Nitto Kasei), length 100 mm × width 100 mm × thickness 25 μm), (copper foil; NA-DFF (Mitsui Metal Mining Co., Ltd.) (Product name: Photec, manufactured by Hitachi Chemical Co., Ltd., thickness: 25 μm) roll laminator (Hitachi Chemical Co., Ltd.) TECHNO PLANT Co., Ltd., HLM-1500) was applied under conditions of pressure 0.4 MPa, temperature 110 ° C., laminating speed 0.4 m / min, and then with an ultraviolet exposure machine (EXM-1172, manufactured by Oak Manufacturing Co., Ltd.). UV light (wavelength 365 nm) from the photosensitive dry film resist side through a negative photomask with a width of 150 μm × 1 mm 20 mJ / cm ² was irradiated to remove the dry film photoresist of unexposed portions of 0.1 to 5 wt% of sodium carbonate 35 ° C. in dilute solution. Thereafter, using a ferric chloride solution, the exposed copper foil of the photosensitive dry film resist was removed by etching, and exposure was performed using a 1-10 wt% sodium hydroxide aqueous solution at 35 ° C. A portion of the photosensitive dry film resist was removed, and a linear electric wiring pattern 103 of L (line width) / S (gap width) = 150/300 μm was formed.

(2) Formation of Ni / Au plating Thereafter, the flexible wiring board is degreased, soft-etched, acid-washed, and the sensitizer (trade name: SA-100, manufactured by Hitachi Chemical Co., Ltd.) for electroless Ni plating is used. After immersing at 5 ° C. for 5 minutes, it was washed with water, and immersed in 83 ° C. electroless Ni plating solution (Okuno Pharmaceutical Co., Ltd., ICP Nicolon GM-SD solution, pH 4.6) for 8 minutes to form a 3 μm Ni film, Washing was performed with pure water.
Next, a substitution gold plating solution (100 mL; HGS-500 and 1.5 g; a bath with potassium gold cyanide / L) (trade name: HGS-500, manufactured by Hitachi Chemical Co., Ltd.) at 85 ° C. for 8 minutes. Immersion was performed to form a 0.06 μm displacement gold film on the Ni film. As a result, a flexible wiring board with double-sided electrical wiring was obtained as the substrate 1 in which the electrical wiring 103 was coated with Ni and Au plating (see FIG. 1B; Cu, Ni, and Au were used as the electrical wiring pattern). 103).

[Examples 1 to 6 and Comparative Example 1]
In Examples 1 to 6 and Comparative Example 1, the following first to third steps were performed using the clad layer forming resin sheet, the core layer forming resin sheet and the substrate prepared as described above. Thus, the optoelectric composite substrate shown in FIG.
In these examples and comparative examples, the thickness of the core pattern 301 is 50 μm, and the thickness of the upper cladding pattern 401 formed on the upper surface of the core pattern 301 is 15 μm. The goal was to produce a photoelectric composite substrate with a constant thickness regardless of location.

Example 1
(1) First Step The 15 μm-thick lower clad layer-forming resin film obtained above is cut into a size of 100 mm × 100 mm, the protective film is peeled off, and vacuum is applied as a flat plate laminator on one side of the substrate 1 surface. Using a pressure laminator (MVLP-500, manufactured by Meiki Seisakusho Co., Ltd.), a SUS plate with a thickness of 2 mm was attached to the hot plate on the resin surface side of the lower clad layer, vacuumed to 500 Pa or less, pressure 0.4 MPa, The lower cladding layer 2 was formed by thermocompression bonding under the conditions of a temperature of 100 ° C. and a pressurization time of 30 seconds (see FIG. 1C). Next, ultraviolet light (wavelength 365 nm) is emitted from the supporting film side at a position 2 mm away from the electric wiring pattern 103 through the negative photomask perpendicular to the electric wiring pattern 103 and having a width of 400 μm × 80 mm with the above-described ultraviolet exposure machine. Was irradiated with 250 mJ / cm ² , the support film was peeled off, and the lower clad layer 2 was etched using a developer (1% aqueous potassium carbonate solution) to form a lower clad pattern 201. Subsequently, it was washed with water, irradiated with 4 J / cm ^{2 of} ultraviolet rays (wavelength 365 nm) from the surface of the lower clad pattern 201 using the above exposure machine, and then heated and dried and cured at 170 ° C. for 1 hour to obtain a thickness. A lower cladding pattern 201 having a width of 15 μm and a width L of 400 μm was formed (FIG. 1D).

(2) Second Step Next, the 65 μm core layer forming resin film is evacuated to 500 Pa or less using the vacuum laminator from the lower clad pattern 201 forming surface side, and then the pressure is 0.4 MPa. The core layer 3 was formed by thermocompression bonding under the conditions of a temperature of 100 ° C. and a pressurization time of 30 seconds (see FIG. 1E). At this time, a SUS plate having a thickness of 2 mm was attached to the hot plate on the core layer forming resin surface side of the vacuum laminator, and planarization was performed simultaneously with the lamination of the core layer forming resin. The total thickness of the lower clad pattern 201 and the core layer 3 laminated on the lower clad pattern 201 and the thickness difference between the core layer 3 formed on the substrate 1 were measured and found to be 1 μm.
Next, through the negative photomask having 50 μm × 50 mm (three) openings from the core layer 3 side, alignment is performed so that the openings are on the lower clad pattern 201, and the above ultraviolet exposure machine Were irradiated with 700 mJ / cm ^{2 of} ultraviolet rays (wavelength 365 nm), and then exposed to light at 80 ° C. for 5 minutes and then heated. Thereafter, the PET film as the support film is peeled off, and the core layer 3 is etched using a developer (propylene glycol monomethyl ether acetate / N, N-dimethylacetamide = 8/2, mass ratio) did. Then, it wash | cleaned using the washing | cleaning liquid (isopropanol), and heat-dried for 10 minutes at 100 degreeC (refer FIG.1 (f) and FIG. 2).
<Detailed Description of Position of Core Pattern 301>
The three core patterns 301 were formed so that the distances a and b in FIG. 1F were 50 μm, respectively, and the central core pattern 301 was the center in the width L direction of the lower core pattern 201.

(3) Third Step Next, the 79 μm thick resin film for forming the upper clad layer from which the protective film has been peeled is applied to the vacuum pattern laminator (MVLP-500, manufactured by Meiki Seisakusho Co., Ltd.) from the core pattern 301 forming surface side. After vacuuming to 500 Pa or less, lamination was performed by thermocompression bonding under conditions of a pressure of 0.4 MPa, a temperature of 110 ° C., and a pressing time of 30 seconds. At this time, a SUS plate having a thickness of 2 mm was attached to a hot plate on the resin surface side of the upper clad layer forming resin of the vacuum laminator, and planarization was performed simultaneously with the lamination of the upper clad layer forming resin.
Further, after irradiating 150 mJ / cm ² with ultraviolet rays (wavelength 365 nm) using the negative photomask used in forming the lower clad pattern 201, the support film is peeled off, and a developer (1% aqueous potassium carbonate solution) is used. The upper clad layer 4 was etched to form an upper clad pattern 401. Subsequently, the substrate was washed with water, irradiated with 4 J / cm ^{2 of} ultraviolet rays (wavelength 365 nm) from the surface of the upper clad pattern 401 using the above exposure machine, and then heated and dried and cured at 170 ° C. for 1 hour to obtain an electric wiring board. An optoelectric composite substrate 6 having an optical waveguide 5 formed on a part of the substrate 1 was manufactured (see FIG. 1H).
Table 1 shows the thicknesses of the lower clad layer forming resin sheet, the core layer forming resin sheet, and the upper clad layer forming resin sheet used. Table 1 shows values of the width L, the distance a, and the distance b of the lower cladding pattern.

(4) Evaluation The produced photoelectric composite substrate 6 was allowed to stand on a flat surface, and the floating (warping amount) of the substrate 1 was measured from the flat surface to be 0.1 μm.
The thickness of the three core patterns 301 and the thickness of the upper clad pattern 401 formed on the upper surface of the core pattern 301 were measured. Also, the thickness difference Δ between the maximum thickness and the minimum thickness among the three core patterns 301 is calculated, and 20 μm or more at which the thickness difference Δ greatly differs in the coupling efficiency with the optical element × 10 μm -20 μm or less was evaluated as Δ, 10 μm or less as ◯, and 5 μm or less as ◎. These values and determination results are shown in Table 1. Further, the thickness difference Δ between the maximum thickness and the minimum thickness among the upper clad layers formed on the three core patterns 301 is calculated, and the thickness difference Δ is 20 μm or more × 10 μm to 20 μm or less. Δ, 10 μm or less was judged as “◯”, and 5 μm or less was judged as “◎”.

Examples 2-6
A photoelectric composite substrate 6 was prepared in the same manner as in Example 1 except that the dimensions of the various films, the width L, the distance a, and the distance b were as shown in Table 1, and then evaluated in the same manner as in Example 1. went. The results are shown in Table 1.

Comparative Example 1
In Comparative Example 1, development was not performed after forming the lower cladding layer 2 in the first step. That is, in Comparative Example 1, the lower clad layer 2 itself is used as the lower clad pattern 201. Therefore, in the comparative example 1, the lower clad pattern 201 is formed on the entire surface of the substrate 1, and the width L of the lower clad pattern 201 is 100 mm.
A photoelectric composite substrate was produced in the same manner as in Example 1 except that this point and the dimensions, distance a, and distance b of various films were as shown in Table 1.
In the obtained photoelectric composite substrate, the electric wiring pattern 103 was completely buried in the lower cladding layer 2. In the obtained photoelectric composite substrate, the electric wiring pattern 103 was completely buried in the lower cladding layer 2. The produced photoelectric composite substrate 6 was allowed to stand on a flat surface, and the floating (warping amount) of the substrate 1 was measured from the flat surface to be 20 mm.

As described above in detail, the optical waveguide can be formed on a part of the substrate with high alignment accuracy, and a core pattern having an arbitrary thickness can be formed. Since the optical waveguide is formed on a part of the substrate, there is little warping of the substrate. If the optical waveguide can be manufactured and the substrate is an electric wiring board, the electric wiring pattern can be exposed on the same plane as the optical waveguide forming surface, so that it is possible to manufacture an optical waveguide and an optoelectric composite substrate that can be easily mounted.
Therefore, it is extremely practical as an optoelectric composite substrate having an optical waveguide in a part of the substrate.

1 Board (electrical wiring board)
DESCRIPTION OF SYMBOLS 101 Substrate body 102 Metal layer 103 Electrical wiring pattern 2 Lower clad layer 201 Lower clad pattern 3 Core layer 301 Core pattern 4 Upper clad layer 401 Upper clad pattern 5 Optical waveguide 6 Photoelectric composite substrate

Claims (12)

An optical waveguide manufacturing method in which an optical waveguide having a lower clad pattern and a core pattern is laminated on a part of a surface of a substrate,
After forming a lower clad layer by laminating a lower clad layer forming resin on the upper surface of the substrate, the lower clad layer is patterned to form a lower clad pattern so that a part of the surface of the substrate is exposed. And the process of
After a core layer forming resin is pressure laminated on the lower cladding pattern and the substrate to form a core layer, the core layer is patterned to form a core pattern having a desired thickness only on the lower cladding pattern. And in order,
In the second step, after the pressure lamination , the core layer is flattened by pressing from the opposite side of the core layer to the substrate,
The method for producing an optical waveguide, wherein the core layer forming resin is made of a core layer forming resin film, and the thickness of the core layer forming resin film before lamination is larger than the thickness of the core pattern.   The method for manufacturing an optical waveguide according to claim 1, wherein a thickness of the core layer-forming resin film before lamination is equal to or less than a total thickness of the lower cladding pattern and the core pattern. 3. The method of manufacturing an optical waveguide according to claim 1, wherein, when flattening by pressurization, the core layer is pressurized with a rigid plate from the opposite side of the core layer to the substrate. The difference in total thickness between the thickness of the core layer on the substrate and the lower cladding pattern formed on the substrate and the core layer on the lower cladding pattern is 15 μm or less. the method of manufacturing an optical waveguide according to. The lower clad pattern has a rectangular parallelepiped shape, and the core pattern extends parallel to a pair of side surfaces of the lower clad pattern;
The lower cladding pattern has a width of 40 mm or less in the direction orthogonal to the extending direction of the core pattern,
5. The core pattern according to claim 1, wherein the core pattern is located 0.1 μm or more inward in the width direction with respect to a pair of side surfaces of the lower clad pattern in a surface of the lower clad pattern. Manufacturing method of optical waveguide.   The method for manufacturing an optical waveguide according to claim 1, wherein the number of the core patterns formed on the lower cladding pattern is three or more.   The method for manufacturing an optical waveguide according to claim 1, wherein an area obtained by removing the lower cladding layer in the first step is larger than an area of the lower cladding pattern. After the second step, after forming the upper clad layer by laminating the core pattern, the lower clad pattern, and the upper clad layer forming resin from the upper surface side of the substrate, a part of the surface of the substrate is exposed. The optical waveguide manufacturing according to claim 1, further comprising a third step of patterning the upper clad layer to form an upper clad pattern on the lower clad pattern and the core pattern. Method.   The upper clad layer forming resin comprises an upper clad layer forming resin film, and the upper clad layer forming resin film has a thickness of the lower clad pattern and the core pattern formed on the lower clad pattern. The method for producing an optical waveguide according to claim 8, wherein the thickness is equal to or greater than a total thickness.   In the third step, after laminating the upper clad layer forming resin, the upper clad layer forming resin is flattened to form the upper clad layer, whereby the lower clad pattern and the lower clad pattern are formed. The optical waveguide according to claim 8 or 9, wherein a total thickness of the formed core pattern and the upper cladding layer formed on the core pattern and a thickness of the upper cladding layer formed on the substrate are made constant. A method for manufacturing a waveguide. A method for producing an optoelectric composite substrate comprising an electrical wiring board and an optical waveguide formed on a part of the surface of the electrical wiring board,
The manufacturing method of the photoelectric composite board | substrate which uses an electrical wiring board as the said board | substrate, and manufactures an optical waveguide in a part of surface of this electrical wiring board by the manufacturing method of the optical waveguide in any one of Claims 1-10 . The method of manufacturing an optoelectric composite substrate according to claim 11 , wherein the electric wiring board has an electric wiring pattern on a surface on which the optical waveguide is formed.

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