JP2015203841A - Light guide and production method of the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light guide which has less processing variation and which can suppress peeling on an interface with a substrate.SOLUTION: A light guide comprises: clad layers 2, 4; and a core pattern 3 for light signal transmission, on a light guide formation surface 11 of a substrate 1. At least one end of the core pattern 3 for light signal transmission on a light axis is a light input/output end surface 5 in which a light signal is inputted or light signal is outputted in approximately parallel to the light guide formation surface 11, and the light input/output end surface 5 is disposed on a projection part 6 projecting from an outer periphery of the substrate 1.

Description

  The present invention relates to an optical waveguide and a method for manufacturing the optical waveguide.

  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. In particular, as an optical transmission path for using light for short-distance signal transmission between boards in a router and a server device, the degree of freedom of wiring is higher than that of an optical fiber and the density can be increased. It is desirable to use an optical waveguide. Among them, an optical waveguide using a polymer material excellent in processability and economy is promising.

As an optical waveguide, an optical waveguide in which a lower clad layer is hardened on a substrate, a core pattern is formed on the lower clad layer, and an upper clad layer is laminated on the lower clad and the core pattern is proposed. (For example, refer to Patent Document 1).
When a plurality of such optical waveguides are arranged in a sheet shape, it is necessary to cut the optical waveguide with a substrate into pieces after forming the optical waveguide.

  In general, laser processing, cutting processing using a dicing saw and a router, shearing processing using a blade die and a die, and the like are used for cutting an optical waveguide with a substrate.

JP 2006-011210 A

  However, in the above processing method, burrs are generated due to differences in workability between the substrate and portions other than the substrate (optical signal transmission core pattern, lower clad layer, upper clad layer, etc.) in the optical waveguide, or the end face is There have been problems such as tilting, discontinuous end faces, and peeling due to low adhesion between the substrate and a portion other than the substrate.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide an optical waveguide and a method for manufacturing the optical waveguide that can reduce the processing variation and suppress the peeling at the interface with the substrate.

  As a result of intensive studies to solve the above-mentioned problems, the present inventors have found that the above-mentioned problems can be solved by making the optical input / output end face project from the outer periphery of the substrate. The present invention has been completed based on such knowledge.

That is, the present invention
(1) An optical waveguide comprising a clad layer and an optical signal transmission core pattern on an optical waveguide forming surface of a substrate,
At least one end on the optical axis of the optical signal transmission core pattern is an optical input / output end surface that inputs or outputs an optical signal in a direction substantially parallel to the optical waveguide forming surface,
An optical waveguide in which the light input / output end surface is present in a protruding portion protruding from the outer periphery of the substrate;
(2) The optical waveguide according to (1), wherein the protruding portion is made of the same material as the cladding layer and / or the optical signal transmission core pattern,
(3) The optical waveguide according to (1) or (2), wherein at least a part of the protrusion is an orthogonal pattern substantially orthogonal to the light transmission core pattern,
(4) The clad layer is provided on the optical waveguide forming surface, and is provided so as to cover the lower clad layer provided with the optical signal transmission core pattern on one side and the optical signal transmission core pattern. The optical waveguide according to any one of (1) to (3), comprising an upper cladding layer,
(5) A distance from the end point of the light transmission core pattern on the light input / output end face side or a connection portion between the light transmission core pattern and the protrusion to the light input / output end face is greater than zero. The optical waveguide according to any one of (1) to (4), which is 200 μm or less,
(6) The optical waveguide according to any one of (1) to (5), wherein the protrusion is present on at least a part of the outer periphery of the substrate.
(7) The method for manufacturing an optical waveguide according to any one of (1) to (6), wherein a cladding layer and an optical signal transmission core pattern are sequentially stacked on a substrate;
And a step of processing the cladding layer and / or the optical signal transmission core pattern by photolithography to form a protruding portion protruding from the outer periphery of the substrate.

  According to the present invention, it is possible to provide an optical waveguide and a method for manufacturing the optical waveguide that can reduce processing variations and suppress separation at the interface with the substrate.

It is sectional drawing which shows the one aspect | mode of the optical waveguide which concerns on the 1st Embodiment of this invention. It is a top view which shows the one aspect | mode of the optical waveguide which concerns on the 1st Embodiment of this invention. It is process sectional drawing which shows the manufacturing method of the optical waveguide which concerns on the 1st Embodiment of this invention. It is sectional drawing which shows the one aspect | mode of the optical waveguide which concerns on the 2nd Embodiment of this invention. It is process sectional drawing which shows the manufacturing method of the optical waveguide which concerns on the 2nd Embodiment of this invention.

(First embodiment)
As shown in FIG. 1, the optical waveguide according to the first embodiment of the present invention includes clad layers 2 and 4 and an optical signal transmission core pattern 3 on an optical waveguide forming surface 11 of a substrate 1. In the optical waveguide according to the first embodiment of the present invention, at least one end on the optical axis of the optical signal transmission core pattern 3 inputs or outputs an optical signal in a direction substantially parallel to the optical waveguide forming surface 11. This is the light input / output end face 5, and the light input / output end face 5 exists on the protruding portion 6 protruding from the outer periphery of the substrate 1.

[substrate]
The substrate 1 imparts toughness to the optical waveguide. Moreover, the board | substrate 1 can suppress a fracture | rupture of an optical waveguide, when forming an optical path conversion mirror using a dicing saw etc. in an optical waveguide. Further, when the optical signal transmission core pattern 3 having a plurality of channels is formed on the clad layer (lower clad layer 2), the shrinkage of the optical waveguide is suppressed and the pitch between the optical signal transmission core patterns 3 is improved. Can keep.

From the above viewpoint, the material of the substrate 1 is, 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, with a resin layer. Examples thereof include a plastic film, a plastic film with a metal layer, and an electric wiring board.
When it is desired to impart flexibility to the optical waveguide, it is preferable to use a material having flexibility and toughness as the substrate 1. Examples of the flexible and tough substrate 1 include polyesters such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate, polyethylene, polypropylene, polyamide, polycarbonate, polyphenylene ether, polyether sulfide, polyarylate, liquid crystal polymer, and polysulfone. , Polyethersulfone, polyetheretherketone, polyetherimide, polyamideimide, and polyimide are preferable.

  The thickness of the substrate 1 is not particularly limited, but is preferably in the range of 5 μm to 200 μm, and more preferably in the range of 10 μm to 100 μm. When the thickness of the substrate 1 is 5 μm or more, there is an advantage that rigidity is easily obtained and the strength as a carrier film is easily obtained, and when it is 200 μm or less, there is an advantage of excellent workability.

[Lower cladding layer and upper cladding layer]
The clad layer is preferably composed of a lower clad layer 2 and an upper clad layer 4. The lower cladding layer 2 is provided on the optical waveguide forming surface 11, and the optical signal transmission core pattern 3 is provided on one surface side. The upper cladding layer 4 is provided so as to cover the optical signal transmission core pattern 3.
The lower clad layer 2 and the upper clad layer 4 are not particularly limited as long as they are resins that have a lower refractive index than the optical signal transmission core pattern 3 and are cured by light and / or heat. Photosensitive resins and thermosetting resins Etc. can be used suitably. The clad layer forming resins for forming the lower clad layer 2 and the upper clad layer 4 may contain the same or different components, and may have the same or different refractive indexes.

The lower cladding layer 2 and the upper cladding layer 4 are formed by laminating and patterning a cladding layer forming resin layer. The method for laminating the clad layer forming resin layer is not particularly limited. For example, the clad layer forming resin may be laminated by dissolving the resin for forming the clad layer in a solvent. A resin film may be laminated.
As a method for forming the lower clad layer 2 and the upper clad layer 4, in the case of coating, the method is not limited, and a clad layer forming resin may be coated by a conventional method.
Further, when a laminate is adopted as a method for forming the lower cladding layer 2 and the upper cladding layer 4, the cladding layer forming resin film used for the lamination is obtained by, for example, dissolving the cladding layer forming resin in a solvent, It can be easily manufactured by applying to a carrier film and removing the solvent.

The thickness of the lower cladding layer 2 and the upper cladding layer 4 is not particularly limited, but the thickness after pattern formation is preferably in the range of 5 μm to 500 μm, and in the range of 10 μm to 100 μm. More preferably. When the thickness after pattern formation is 5 μm or more, the cladding thickness necessary for light confinement can be secured, and when it is 500 μm or less, a low-profile optical waveguide can be obtained. Furthermore, it is more preferable that the average thickness of the lower clad layer 2 and the upper clad layer 4 after patterning is within the above-mentioned range.
Further, the thicknesses of the lower clad layer forming resin film and the upper clad layer forming resin film for forming the lower clad layer 2 and the upper clad layer 4 are particularly limited as long as the above-described thickness pattern can be formed. Although it is not a thing, it is preferable that the thickness of a resin film is 500 micrometers or less from a viewpoint that it is easy to obtain the resin film of uniform film thickness.

[Core pattern for optical signal transmission]
The optical signal transmission core pattern 3 can be formed, for example, by laminating a resin layer for forming a core layer, and exposing and developing. The core layer forming resin preferably has a higher refractive index than the lower cladding layer 2 and the upper cladding layer 4 and can be patterned by actinic rays. The method for forming the core layer forming resin layer before patterning is not limited. For example, the core layer forming resin may be laminated by dissolving the resin for forming the core layer in a solvent. A resin film may be laminated.

The thickness of the optical signal transmission core pattern 3 is not particularly limited, but the thickness of the optical signal transmission core pattern 3 after formation is preferably in the range of 10 μm to 100 μm, and in the range of 30 μm to 90 μm. It is more preferable that When the thickness of the optical signal transmission core pattern 3 is 10 μm or more, there is an advantage that the alignment tolerance can be increased in the coupling with the light emitting / receiving element or the optical fiber after the optical waveguide is formed. There is an advantage that the coupling efficiency is improved in coupling with the light emitting / receiving element or the optical fiber after the waveguide is formed. In order to obtain such a thickness, the thickness of the resin film for forming the core layer may be adjusted as appropriate. From the viewpoint of easily obtaining a resin film having a uniform film thickness, the thickness of the resin film is 100 μm or less. There should be.
As the resin for forming the core layer, it is preferable to use a resin that is transparent to the light of the optical signal to be used and can be cured by actinic rays to form a pattern.

[Projection]
The protrusion 6 is preferably made of the same material as the cladding layers 2, 4 and / or the optical signal transmission core pattern 3. In the optical waveguide shown in FIGS. 1 and 2, the protruding portion 6 is made of the same material as the optical signal transmission core pattern 3 and is formed integrally with the optical signal transmission core pattern 3. The protrusions 6 are made of the same material as the cladding layers 2, 4 and / or the optical signal transmission core pattern 3, and are exposed and developed in the same manner as the cladding layers 2, 4 and the optical signal transmission core pattern 3. Can be formed. The protrusion 6 is formed integrally with the cladding layers 2, 4 or the optical signal transmission core pattern 3, thereby suppressing peeling during formation of the cladding layers 2, 4 or the optical signal transmission core pattern 3. Can do.
It is preferable to use a protrusion 6 that can be patterned with actinic rays. The formation method of the clad layer forming resin and the core layer forming resin layer before patterning is not limited. For example, the clad layer forming resin and the core layer forming resin are dissolved and applied in a solvent and laminated. Alternatively, a clad layer forming resin film and a core layer forming resin film prepared in advance may be laminated.
As shown in FIG. 4, the clad layer and the core layer formed on the substrate surface opposite to the optical waveguide with a mirror may be the same material or different materials from the clad layers 2 and 4 and the optical transmission core pattern 3. . In the case where an optical signal is not transmitted, light transmission is not required, and any material that can be patterned may be used. In particular, it is preferable that the same material as that for forming the protruding portion 6 is used because it is difficult for the interface to appear when patterning and a step is prevented from occurring on the light input / output end face 5. Further, when the protruding portion 6 is formed of the same material as the optical transmission core pattern 3 and the adhesive force between the substrate 1 and the core layer forming resin is weak, as shown in FIG. A clad layer may be provided between the core layer on the surface and the substrate 1.

  As shown in FIG. 2, at least a part of the protruding portion 6 is preferably an orthogonal pattern 8 that is substantially orthogonal to the optical transmission core pattern 3. The orthogonal pattern 8 shown in FIG. 2 is a surface that becomes the light input / output end face 5 in the protrusion 6, and the entire surface is substantially orthogonal to the light transmission core pattern 3. By providing the orthogonal pattern 8, a flat portion is formed on the end surface, and it is possible to satisfactorily abut the alignment with a connector or the like using the flat portion. The flat part is a part including at least the optical input / output unit 5 and may be any part that protrudes in the opposite direction to the optical signal transmitting core pattern 3.

  It is preferable that the protruding portion 6 exists on at least a part of the outer periphery of the substrate 1. Since the protruding portion 6 exists on the outer periphery of the substrate 1, the interface between the substrate 1 and the cladding layers 2, 4 or the optical signal transmission core pattern 3 does not exist on the outer periphery, and peeling occurs starting from the interface. It does not occur, and the strength near the light input / output end face 5 can be secured. Moreover, since the protrusion part 6 exists in the board | substrate 1 outer periphery, it can prevent that an end surface inclines or an end surface is formed discontinuously.

From the end point X ₁ of the light input and output end face 5 side of the light transmitting core pattern 3, or from the connecting portion X ₂ of the light transmitting core pattern 3 and the protruding portion 6, the distance to the light output end face 5, from 0 If it is large and is 200 μm or less, it is possible to reduce the coupling loss between the core pattern 3 for light transmission and an external light receiving / emitting element, optical fiber or the like. When the distance from X ₁ or X ₂ to the light input / output end face 5 is 5 μm or more and 100 μm or less, a coupling loss can be further formed, and the formation of the protruding portion 6 is facilitated, more preferably 35 μm or more and 100 μm. The following is more preferable because the alignment at the time of forming the protruding portion by photolithography processing is facilitated. By setting it in the above range, it is possible to reduce the coupling loss between the light transmitting core pattern 3 and the external light receiving and emitting elements, optical fibers, and the like.

[Optical path conversion mirror]
The optical path conversion mirror 7 has an optical path conversion structure in which the optical signal propagated through the optical signal transmission core pattern 3 extending in a direction parallel to the substrate plane is converted in a direction substantially perpendicular to the substrate 1 and the upper cladding layer 4. There is no particular limitation, and it may be an air reflection mirror formed by providing a 45 ° cutout in the optical signal transmission core pattern 3 or a metal reflection mirror having a reflection metal layer formed in the cutout portion. Good.
The optical path conversion mirror 7 can be formed by cutting or cutting the optical axis of the optical signal transmission core pattern 3 in the optical waveguide using a dicing saw or the like from the upper clad layer 4 side. The optical path conversion mirror 7 can also be formed by cutting the optical signal transmission core pattern 3 from the substrate 1 side using a dicing saw or the like. The optical path conversion mirror 7 is preferably 45 ° C. with respect to the traveling direction of the optical signal transmission core pattern 3.

  Below, the manufacturing method of the optical waveguide which concerns on the 1st Embodiment of this invention is demonstrated using FIG.

  As a process shown in FIG. 3A, the substrate sheet is processed into a desired shape of the substrate 1. The shape processing method at this time is not particularly limited, and examples thereof include cutting using a dicing saw, processing using laser ablation, processing using a blade die, and the like.

Next, as a step shown in FIG. 3B, the lower cladding layer 2 is formed on the optical waveguide forming surface 11 of the substrate 1.
Although there is no restriction | limiting in particular as the pattern formation method of the lower clad layer 2, For example, the lower clad layer forming tree composition is applied so that the board | substrate 1 may be covered, or the lower clad layer formation previously apply | coated to the film form The lower clad layer 2 having a desired pattern can be formed by laminating a resin film and patterning using a photolithography process or the like. In the case of performing photolithography, a photosensitive resin composition is used as the lower clad layer forming resin composition.

  Next, as a step shown in FIG. 3C, a core layer forming resin layer is laminated on the substrate 1 and the lower cladding layer 2. The method for laminating the resin layer for forming the core layer is not particularly limited. For example, a spin film method and a dip coat method, or a dry film core layer formed in advance similarly to the lower clad layer 2 described above. The core layer-forming resin composition can be laminated on the substrate 1 and the lower cladding layer 2 by a laminating method or the like.

Next, as a step shown in FIG. 3D, the optical signal transmitting core pattern 3 and the protruding portion 6 are formed. As a method of forming the optical signal transmission core pattern 3 and the protruding portion 6, it can be formed by patterning by photolithography.
It is preferable to form the optical signal transmitting core pattern 3 and the protruding portion 6 by photolithography because the mutual positional relationship is formed with high accuracy. When performing photolithography processing, the optical signal transmitting core pattern 3 and the protruding portion 6 are simultaneously formed using a single light-shielding mask, whereby the positional relationship between the optical signal transmitting core pattern 3 and the protruding portion 6 is determined. Is more preferable because it can be made more accurate. Further, development in the same process is preferable because the optical signal transmitting core pattern 3 and the protrusion 6 can be formed with high accuracy. As a result, the light input / output end face 5 having the same surface roughness as that of the side face of the optical signal transmission core pattern 3 having no problem in light propagation can be obtained.
In the optical waveguide according to the present invention, since the protruding portion 6 protrudes from the outer periphery of the substrate 1, the end surface serving as the light input / output end surface 5 can be processed by photolithography without using physical processing. . Since the protruding portion 6 can be formed by photolithography, burrs are generated on the light input / output end surface 5 provided in the protruding portion 6, the light input / output end surface 5 is inclined to the extent that it interferes with light input / output, It is possible to eliminate problems that occur when the end surface 5 is formed discontinuously or formed by physical processing such as the light input / output end surface 5 being rough. In other words, the light input / output end face 5 formed on the protruding portion 6 can have good optical characteristics with less of the above-mentioned problems.

Next, as a step shown in FIG. 3E, an upper clad layer 4 is formed so as to cover the optical signal transmission core pattern 3.
The pattern forming method of the upper clad layer 4 is not particularly limited. For example, a method of partially applying the resin composition for forming the upper clad layer to a desired portion (optical signal transmission core pattern 3), or a film in advance. A method of partially laminating a resin film for forming an upper clad layer coated in a shape on a desired portion, or forming an upper clad layer by applying an upper clad layer forming resin composition over the entire surface, or by applying a film in advance The upper clad layer 4 can be formed by laminating a resin film for use and patterning using a photolithography process or the like.

If necessary, an optical path conversion mirror 7 is formed on the optical signal transmission core pattern 3 as a step shown in FIG.
The method for forming the optical path conversion mirror 7 is not particularly limited, and a known method can be applied. For example, the optical signal transmission core pattern 3 can be formed by cutting the optical signal transmission core pattern 3 from the surface where the optical signal transmission core pattern 3 is formed using a dicing saw or the like. The angle of the optical path conversion mirror 7 to be formed is preferably about 45 °.
Moreover, it is good also as a mirror which vapor-deposited metals, such as gold | metal | money, to the optical path conversion mirror 7 using a vapor deposition apparatus, and was provided with the reflective metal layer.

[Second Embodiment]
As shown in FIG. 4, the optical waveguide according to the second embodiment of the present invention has a lower clad layer 2 and an optical signal on both surfaces of the substrate 1 as compared with the optical waveguide shown in the first embodiment. The difference is that the transmission core pattern 3 is formed. In this embodiment, the resin such as the clad layer and the core layer can be used to make the interface between the substrate 1 and the resin layer in the vicinity of the protruding portion 6, and further suppress the interface peeling between the substrate 1 and the resin layer. it can. Regarding the optical waveguide according to the second embodiment, descriptions of portions that are substantially the same as those of the optical waveguide according to the first embodiment will be omitted because they are redundant descriptions.

  Below, the manufacturing method of the optical waveguide which concerns on the 2nd Embodiment of this invention is demonstrated using FIG.

  As a process shown in FIG. 5A, a substrate sheet whose both surfaces are the optical waveguide forming surfaces 11 is processed into a desired shape of the substrate 1. The shape processing method at this time is not particularly limited, and examples thereof include cutting using a dicing saw, processing using laser ablation, processing using a blade die, and the like.

  Next, as a step shown in FIG. 5B, the lower clad layer 2 is formed on both surfaces of the substrate 1. At this time, one surface functions as a lower cladding layer 2 and the other functions as an adhesive layer between the core layer and the substrate 1.

Next, as a step shown in FIG. 5C, a core layer forming resin layer is laminated on the substrate 1 and the lower clad layer 2 (both sides). Then, the optical signal transmission core pattern 3 and the protrusion 6 are formed by photolithography. At this time, the core layer formed on the surface opposite to the optical signal transmission core pattern 3 is not limited to the optical signal transmission core pattern 3 and may be a pattern capable of forming at least the protruding portion 6. The light transmission core pattern 3 may be formed on both sides of the substrate 1.
When the optical signal transmission core pattern 3 and the protrusion 6 are simultaneously formed by the pattern exposure / development process, the optical input / output end face 5 is formed by the same photomask as the optical signal transmission core pattern 3. It is preferable because the correlation between these positions can be obtained. Specifically, after exposing the optical signal transmission core pattern 3 and the protruding portion 6 (including the light input / output end face 5) pattern from one surface, the substrate 1 and the light input / output end face 5 are exposed from the back surface. What is necessary is just to expose by arrange | positioning to the light-dark boundary (bright part is the board | substrate 1 side) of a photomask. In other words, among the core layers formed from both sides, the light input / output end face 5 exposes the core layers on both sides in a lump from one side. A similar structure can be obtained even if the order of exposure described above is reversed. Thereafter, development is performed to obtain a pattern in which the correlation between the positions of the optical signal transmitting core pattern 3 and the protruding portion 6 is obtained.

  Next, as a step shown in FIG. 5D, the upper clad layer 4 is formed so as to cover at least one of the optical signal transmission core patterns 3.

  If necessary, the optical path conversion mirror 7 is formed on the optical signal transmission core pattern 3 as a step shown in FIG.

  Even in the optical waveguide according to the second embodiment of the present invention configured as described above, the same effect as that of the optical waveguide according to the first embodiment can be obtained.

EXAMPLES Hereinafter, although an Example demonstrates this invention still in detail, this invention is not limited to a following example, unless the summary is exceeded.
(Example 1)
[Clad layer forming resin film]
<Production of (A) (meth) acrylic polymer (base polymer)>
46 parts by mass of propylene glycol monomethyl ether acetate and 23 parts by mass of methyl lactate were weighed and transferred to a flask equipped with a stirrer, a cooling pipe, a gas introduction pipe, a dropping funnel and a thermometer, and stirred while introducing nitrogen gas. It was. 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. Furthermore, stirring was continued at 95 ° C. for 1 hour to obtain a solution of (A) (meth) acrylic polymer (solid content: 45% by mass).

<Measurement of weight average molecular weight>
(A) The weight average molecular weight (in terms of standard polystyrene) of the (meth) acrylic polymer was measured using GPC (“SD-8022”, “DP-8020” and “RI-8020” manufactured by Tosoh Corporation), It was 3.9 × 10 ⁴ . As the column, “Gelpack GL-A150-S” and “Gelpack GL-A160-S” manufactured by Hitachi Chemical Co., Ltd. were used.
<Measurement of acid value>
As a result of measuring the acid value of (A) (meth) acrylic polymer, it was 79 mgKOH / g. The acid value was calculated from the amount of 0.1 mol / L potassium hydroxide aqueous solution required to neutralize the (A) (meth) acrylic polymer 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.

<Preparation of resin varnish for forming clad layer>
As a base polymer, (A) (meth) acrylic polymer solution (solid content 45 mass%) 84 mass parts (solid content 38 mass parts), (B) Urethane (meth) acrylate having a polyester skeleton as a photocuring component (new) 33 parts by mass of “U-200AX” manufactured by Nakamura Chemical Co., Ltd., and 15 parts by mass of urethane (meth) acrylate having a polypropylene glycol skeleton (“UA-4200” manufactured by Shin-Nakamura Chemical Co., Ltd.), (C) thermosetting As a component, 20 parts by mass of a polyfunctional block isocyanate solution (solid content: 75% by mass) obtained by protecting an isocyanurate type trimer of hexamethylene diisocyanate with methyl ethyl ketone oxime (“Sumijour BL3175” manufactured by Sumika Bayer Urethane Co., Ltd.) 15 parts by weight), (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 mass, bis (2,4,6-trimethylbenzoyl) ) 1 part by mass of 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 diameter 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.

<Preparation of a resin film for forming a cladding layer>
The resin varnish for forming a clad layer obtained above is coated on a non-treated surface of a PET film (“Cosmo Shine A4100” manufactured by Toyobo Co., Ltd., thickness 50 μm) as a support film (multicoater TM- MC, manufactured by Hirano Tech Seed Co., Ltd.) and dried at 100 ° C. for 20 minutes, and then a surface release treatment PET film (“Purex A31” manufactured by Teijin DuPont Films, Inc., 25 μm thick) is pasted as a protective film. A resin film for forming a cladding layer was obtained.
At this time, the thickness of the resin layer formed from the clad layer forming resin varnish can be arbitrarily adjusted by adjusting the gap of the coating machine.

[Resin film for core layer formation]
(A) As a base polymer, 26 parts by mass of phenoxy resin (“Phenototo YP-70” manufactured by Toto Kasei Co., Ltd.), (B) As a photopolymerizable compound, 9,9-bis [4- (2-acryloyloxyethoxy) ) Phenyl] fluorene ("A-BPEF" manufactured by Shin-Nakamura Chemical Co., Ltd.) 36 parts by mass, and 36 parts by mass of bisphenol A type epoxy acrylate ("EA1020" manufactured by Shin-Nakamura Chemical Co., Ltd.), (C) Photopolymerization started As an agent, 1 part by mass of bis (2,4,6-trimethylbenzoyl) phenylphosphine oxide (“Irgacure 819” manufactured by Ciba Japan Co., Ltd.) and 1- [4- (2-hydroxyethoxy) phenyl] -2 -Hydroxy-2-methyl-1-propan-1-one ("Irgacure 2959" manufactured by Ciba Japan KK) Parts by weight, obtained by compounding a resin varnish for forming a core layer by the same method and conditions and formulation of the above cladding layer forming resin varnish except for using 40 parts by mass of propylene glycol monomethyl ether acetate as an organic solvent. Thereafter, pressure filtration and degassing under reduced pressure were performed in the same manner and conditions as described above.
The core layer-forming resin varnish obtained above is applied to the non-treated surface of a PET film (“Cosmo Shine A1517” manufactured by Toyobo Co., Ltd., thickness: 16 μm) as a support film in the same manner as in the above production example. Then, a release PET film (“Purex A31” manufactured by Teijin DuPont Films Ltd., thickness: 25 μm) as a protective film is applied so that the release surface is on the resin side, and a core layer forming resin A film was obtained.
At this time, the thickness of the resin layer formed from the resin varnish for forming the core layer can be arbitrarily adjusted by adjusting the gap of the coating machine.

[Production Example of Optical Waveguide According to First Embodiment]
<Preparation process of substrate>
A 100 mm × 100 mm polyimide film (“Kapton EN” manufactured by Toray DuPont Co., Ltd., thickness: 25 μm) was prepared as a substrate sheet.
Next, the substrate sheet was shaped with the third harmonic (wavelength: 355 nm) of the Nd-YAG laser to form the substrate 1 (see FIG. 3A).

<Formation of lower cladding layer>
After peeling off the protective film of the 15 μm-thick clad layer forming resin film obtained above from the optical waveguide forming surface 11 side of the substrate 1, a vacuum pressure laminator (“MVLP-500” manufactured by Meiki Seisakusho Co., Ltd.) ), And was vacuum-bonded to 500 Pa or less, and then thermocompression bonded under the conditions of a pressure of 0.4 MPa, a temperature of 110 ° C., and a pressurization time of 30 seconds to laminate. Subsequently, ultraviolet rays (wavelength 365 nm) were irradiated at 350 mJ / cm ² through a negative photomask using an ultraviolet exposure machine (“EXM-1172” manufactured by Oak Manufacturing Co., Ltd.). Thereafter, an unnecessary lower clad layer forming resin was removed using a developing solution (1% aqueous potassium carbonate solution), followed by washing with water. Further, irradiation with 3.0 J / cm ² was performed using the above ultraviolet exposure machine, and heat drying and curing operations were performed at 170 ° C. for 1 hour. The thickness of the lower cladding layer 2 was 15 μm from above the substrate 1 (see FIG. 3B).

<Formation of optical signal transmission core pattern and protrusion>
Next, a 120 mm × 120 mm polyimide film (“Kapton EN” manufactured by Toray DuPont Co., Ltd., thickness: 25 μm) is disposed on the surface opposite to the lower clad layer 2 formation surface, and the lower clad layer 2 formation surface formed above. From the side, after removing the protective film from the 46 μm-thick core layer-forming resin film obtained above, a roll laminator (manufactured by Hitachi Chemical Technoplant Co., Ltd., “HLM-1500”) was used, and the pressure was set to 0. Lamination was performed under conditions of 4 MPa, a temperature of 50 ° C., and a laminating speed of 0.2 m / min. Next, using the above-described vacuum pressure laminator (“MVLP-500”, manufactured by Meiki Seisakusho Co., Ltd.), after vacuuming to 500 Pa or less, conditions of pressure 0.4 MPa, temperature 70 ° C., pressurization time 30 seconds And thermocompression bonded. (See FIG. 3C).

Subsequently, the drawing pattern for forming the protruding portion 6 is formed so that the protruding portion 6 is located at the end portion on the optical axis of the optical signal transmitting core pattern 3 on the substrate 1. Is aligned with the same negative photomask having a drawing pattern for forming the optical signal transmitting core pattern 3 so that a desired position on the lower cladding layer 2 is formed.
Then, ultraviolet rays (wavelength 365 nm) were irradiated at 0.8 J / cm ² through a negative photomask using the above-described ultraviolet exposure machine, and post-exposure heating was performed at 80 ° C. for 5 minutes. Thereafter, the PET film as the support film was peeled off and etched using a developer (propylene glycol monomethyl ether acetate / N, N-dimethylacetamide = 8/2, mass ratio). Then, it wash | cleaned using the washing | cleaning liquid (isopropanol), and heat-dried at 100 degreeC for 10 minute (s), and formed the optical signal transmission core pattern 3 and the protrusion part 6 (refer FIG.3 (d)).
The height of the obtained optical signal transmission core pattern 3 from the surface of the lower cladding layer 2 was 45 μm. The core width of the optical signal transmission core pattern 3 was 45 μm. The height of the protruding portion 6 from the bottom surface of the substrate 1 was 8575 μm. The width of the intersecting pattern (core layer) was 50 μm, and the amount of protrusion from the end of the substrate 1 was 30 μm.

<Formation of upper clad pattern>
The 65 μm-thick clad layer-forming resin film obtained above was peeled off from the top of the optical signal transmission core pattern 3 and the protruding portion 6 after the protective film was peeled off. The product was “MVLP-500” (manufactured by Seisakusho Co., Ltd.), vacuumed to 500 Pa or less, and then heat-pressed and laminated under the conditions of a pressure of 0.4 MPa, a temperature of 110 ° C., and a pressurization time of 30 seconds.
Subsequently, the opening center of the negative photomask having the opening and the center of the substrate 1 are aligned, and ultraviolet light (wavelength 365 nm) is applied from the support film side of the clad layer forming resin film using the ultraviolet exposure machine. Was irradiated at 350 mJ / cm ² . Thereafter, the support film was peeled off, an unnecessary upper clad layer forming resin was removed using a developer (1% aqueous potassium carbonate solution), and then washed with water. Further, irradiation with 3.0 J / cm ² was performed using the above ultraviolet exposure machine, and heat drying and curing operations were performed at 170 ° C. for 1 hour. An end of the upper clad layer 4 on the protruding portion 6 side is sandwiched by a pattern perpendicular to the optical signal transmitting core pattern 3 (partly protrudes from the end portion of the substrate 1 toward the optical input / output end face 5 side). (Projection amount: 5 μm)). The thickness of the upper cladding layer 4 was 73 μm from the top of the substrate 1 (see FIG. 3E).

<Formation of optical path conversion mirror>
A 45 ° optical path conversion mirror 7 was formed using a dicing saw (“DAC552” manufactured by Disco Corporation) from the upper clad layer 4 side of the obtained optical waveguide.
Thus, an optical waveguide with a mirror having a protruding portion 6 protruding from the outer periphery of the substrate 1 on the optical axis of the optical signal transmitting core pattern 3 was obtained.

  In the obtained optical waveguide, no burr or the like was observed on the light input / output end face 5 of the protrusion 6. In addition, the obtained optical waveguide was not peeled off at any place other than the substrate even when the upper cladding pattern side was bent inward with a bending radius of 5 mm. When an optical fiber of GI 50 was abutted against the optical input / output end face 5, it was possible to propagate an optical signal satisfactorily and there was little variation in coupling loss.

(Example 2)
[Production Example of Optical Waveguide According to Second Embodiment]
An optical waveguide was manufactured in the same manner as in Example 1 except for the changes described below.
Lower clad layers 2 were provided on both surfaces of the substrate 1 (see FIG. 5B). Next, the optical signal transmission core pattern 3 was provided on both the lower clad layers 2 (see FIG. 5C). Next, the upper clad layer 4 was provided on one optical signal transmission core pattern 3 (see FIG. 5D). Next, a 45 ° optical path conversion mirror 7 was formed by using a dicing saw from the upper clad layer 4 side of the obtained optical waveguide (see FIG. 5E).

  In the obtained optical waveguide, no burr or the like was observed on the light input / output end face 5 of the protrusion 6. In addition, the obtained optical waveguide was not peeled off at any place other than the substrate even when the upper cladding pattern side was bent inward with a bending radius of 5 mm. When an optical fiber of GI 50 was abutted against the optical input / output end face 5, it was possible to propagate an optical signal satisfactorily and there was little variation in coupling loss.

  The optical waveguide of the present invention has excellent optical signal propagation efficiency because no burr or the like occurs on the optical input / output end face, and no separation occurs between the substrate and other portions. It can be applied to a wide range of fields such as connections.

DESCRIPTION OF SYMBOLS 1 ... Substrate 11 ... Optical waveguide formation surface 2 ... Lower clad layer 3 ... Optical signal transmission core pattern 4 ... Upper clad layer 5 ... Optical input / output end face 6 ... Projection 7 ... Optical path conversion mirror

Claims (7)

An optical waveguide comprising a cladding layer and an optical signal transmission core pattern on the optical waveguide forming surface of the substrate,
At least one end on the optical axis of the optical signal transmission core pattern is an optical input / output end surface that inputs or outputs an optical signal in a direction substantially parallel to the optical waveguide forming surface,
An optical waveguide in which the light input / output end surface is present in a protruding portion protruding from the outer periphery of the substrate.   The optical waveguide according to claim 1, wherein the protruding portion is made of the same material as the cladding layer and / or the optical signal transmission core pattern.   The optical waveguide according to claim 1, wherein at least a part of the projecting portion is an orthogonal pattern that is substantially orthogonal to the optical transmission core pattern.   The clad layer is provided on the optical waveguide forming surface, and a lower clad layer provided with the optical signal transmission core pattern on one surface side, and an upper clad layer provided so as to cover the optical signal transmission core pattern The optical waveguide according to claim 1, comprising:   The distance from the end point of the light transmission core pattern on the light input / output end face side or the connection portion between the light transmission core pattern and the protrusion to the light input / output end face is greater than 0 and 200 μm or less. The optical waveguide according to any one of claims 1 to 4.   The optical waveguide according to claim 1, wherein the protruding portion is present on at least a part of the outer periphery of the substrate. A method for producing an optical waveguide according to any one of claims 1 to 6,
Laminating a clad layer and an optical signal transmission core pattern in order on a substrate;
And a step of processing the cladding layer and / or the optical signal transmission core pattern by photolithography to form a protruding portion protruding from the outer periphery of the substrate.