JP2015106034A - Optical waveguide - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical waveguide capable of reducing interlayer peeling, burr generation, and warpage.SOLUTION: An optical waveguide comprises: a lower substrate 11; a lower clad layer 11 provided on the lower substrate 11; a core pattern 13 provided on the lower clad layer 12; an upper clad layer 14 provided on the core pattern 13; an upper substrate 15 provided on the upper clad layer 14; and a groove 17 which includes a groove formation surface 18 communicating with the upper substrate 15, the upper clad layer 14, and the core pattern 13 and in which at least a part of the groove formation surface 18 functions as an optical path conversion mirror 19 which converts an optical path of the optical signal passing the core pattern 13.

Description

  The present invention relates to an optical waveguide used for an optical device and a manufacturing method thereof.

  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 such an optical waveguide is provided with an optical path conversion mirror that performs optical path conversion of an optical signal passing through the core pattern, the optical waveguide is formed from the upper clad layer side using a dicing blade or the like.

JP 2006-011210 A

However, in the conventional optical waveguide, there is a concern that when the optical path conversion mirror is formed using a dicing blade or the like, peeling between the core pattern and the upper clad layer may occur or burrs may occur on the surface layer of the upper clad layer. The When the generated burr adheres to the optical path conversion mirror, there is a problem that the optical loss is deteriorated.
Further, in the conventional optical waveguide, there is a concern that the optical waveguide may be warped when the optical path conversion mirror is formed. When the optical waveguide is warped, there is a problem that handling properties when forming the optical path conversion mirror are lowered.

  The present invention has been made to solve the above-described problems, and an object thereof is to provide an optical waveguide that can reduce the occurrence of peeling and burrs between layers and can reduce warpage, and a method for manufacturing the optical waveguide. And

  As a result of intensive studies, the present inventors have found that the above problem can be solved by using an optical waveguide having substrates on both sides of the optical waveguide. The present invention has been completed based on such knowledge.

That is, the present invention
(1) A core pattern provided on the lower clad layer, an upper clad layer provided on the core pattern, an upper substrate provided on the upper clad layer, the upper substrate, and the upper clad layer And an optical waveguide having a groove forming surface that communicates with the core pattern, and at least a part of the groove forming surface functions as an optical path conversion mirror that performs optical path conversion of an optical signal that passes through the core pattern. ,
(2) The optical waveguide according to (1), wherein the lower cladding layer is provided on a lower substrate.
(3) The optical waveguide according to (1) or (2), wherein the upper substrate is provided at least at a place where the groove is provided,
(4) The optical waveguide according to any one of (1) to (3), wherein the upper substrate is provided on the entire surface of the upper cladding layer.
(5) The optical waveguide according to any one of (1) to (4), including a lid that is provided on the upper substrate and covers the groove.
(6) The optical waveguide according to any one of (1) to (5), wherein an elastic modulus of the upper substrate is higher than an elastic modulus of the upper clad layer.
(7) The optical waveguide according to any one of (2) to (6), wherein a difference in elastic modulus between the lower substrate and the upper substrate is 0 Pa or more and 10 GPa or less.
(8) The optical waveguide according to any one of (5) to (7), wherein a difference in elastic modulus between the upper substrate and the lid is 0 Pa or more and 10 GPa or less.
(9) The optical waveguide according to any one of (2) to (8), wherein the thickness of the upper substrate with respect to the thickness of the lower substrate is 0.5 times or more and 2 times or less.
(10) The optical waveguide according to any one of (5) to (9), wherein the thickness of the lid with respect to the thickness of the upper substrate is not less than 0.5 times and not more than 2 times.
(11) The optical waveguide according to any one of (1) to (10), wherein the groove forming surface communicates the upper substrate, the upper cladding layer, the core pattern, and the lower cladding layer.
(12) The optical waveguide according to any one of (2) to (11), wherein the lower substrate and the upper substrate have polyimide as a main component.
(13) A step of forming a laminate composed of a lower clad layer, a core pattern, an upper clad layer, and an upper substrate, and cutting from the upper substrate side, and communicating the upper substrate, the upper clad layer, and the core pattern. And a step of forming a groove portion that functions as an optical path conversion mirror that performs optical path conversion of an optical signal that passes through the core pattern.
(14) The method of manufacturing an optical waveguide according to (13), wherein the step of forming the stacked body is a step of forming the stacked body on a lower substrate.
(15) The step of laminating the upper substrate includes laminating the upper substrate at least at a location where the groove is provided, (13) or (14),
(16) The step of laminating the upper substrate includes laminating the upper substrate over the entire surface of the upper cladding layer. (13) The method for manufacturing an optical waveguide according to any one of (15),
(17) The method of manufacturing an optical waveguide according to any one of (13) to (16), wherein a lid that covers the optical path conversion mirror is stacked on the upper substrate after the step of forming the groove.
(18) The step of forming the groove provides the method for manufacturing an optical waveguide according to any one of (13) to (17), in which the groove is formed by processing with a dicing blade.

  ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of the optical waveguide and optical waveguide which can reduce peeling and deburring of an interlayer, and reduction of curvature can be provided.

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 process sectional drawing (the 1) of the optical waveguide which concerns on the 1st Embodiment of this invention. It is process sectional drawing (the 2) 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.

(First embodiment)
[Optical waveguide]
As shown in FIG. 1, the optical waveguide according to the first embodiment of the present invention is provided on the lower substrate 11, the lower cladding layer 12 provided on the lower substrate 11, and the lower cladding layer 12. The core pattern 13, the upper clad layer 14 provided on the core pattern 13, the upper substrate 15 provided on the upper clad layer 14, and the upper substrate 15, the upper clad layer 14, and the core pattern 13 are communicated. The groove forming surface 18 is provided, and at least a part of the groove forming surface 18 includes a groove portion 17 that functions as an optical path conversion mirror 19 that performs optical path conversion of an optical signal that passes through the core pattern 13.

  Below, each member used for the optical waveguide which concerns on the 1st Embodiment of this invention is demonstrated in detail.

<Lower substrate and upper substrate>
The lower substrate 11 is provided because it has an effect of suppressing breakage of the optical waveguide when the groove portion 17 is formed using a dicing blade or the like in the optical waveguide while suppressing breakage of the optical waveguide from the lower cladding layer 12 side. It is preferable.
The upper substrate 15 has an effect of reducing the peeling between the core pattern 13 and the upper clad layer 14 and the generation of burrs on the surface layer of the upper clad layer 14 when the groove 17 is formed.
The configuration having the lower substrate 11 and the upper substrate 15 is preferable because there is an effect of reducing warpage generated in the optical waveguide when the groove portion 17 is formed. In addition, the configuration having the lower substrate 11 and the upper substrate 15 is preferable because there is an effect of improving the handling property when the groove portion 17 is formed.

When a material having toughness is used as the lower substrate 11 and the upper substrate 15, toughness can be imparted to the optical waveguide, and peeling between layers and burrs caused by pressurization and vibration at the time of forming the groove portion 17 can be provided. Since generation | occurrence | production can be reduced and curvature can be reduced, it is preferable. In addition, the lower substrate 11 and the upper substrate 15 may be rigid substrates or flexible substrates, but using a flexible substrate can impart flexibility to the optical waveguide. Therefore, it is preferable.
From the above viewpoint, the lower substrate 11 and the upper substrate 15 are, for example, polyesters such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate, polyethylene, polypropylene, polyamide, polycarbonate, polyphenylene ether, polyether sulfide, polyarylate, and liquid crystal. Preferred examples include polymers, polysulfones, polyether sulfones, polyether ether ketones, polyether imides, polyamide imides, polyimides, and flexible electric wiring boards in which electric wirings are formed. More preferable lower substrate 11 and upper substrate 15 include polyimide, a laminate mainly composed of polyimide, and the like from the viewpoint of dimensional stability, heat resistance, and high bending.
The lower substrate 11 and the upper substrate 15 are preferably made of a material that is transparent to the optical signal wavelength transmitted through the optical waveguide because the optical signal can pass through the lower substrate 11 and the upper substrate 15. The lower substrate 11 and the upper substrate 15 are preferably transparent to the wavelength of the inspection light used for the inspection of the core pattern 13 because the visibility of the core pattern 13 can be obtained through the lower substrate 11 and the upper substrate 15. . From the above viewpoint, it is preferable that the lower substrate 11 and the upper substrate 15 are transparent to at least one of ultraviolet light, visible light, and infrared light.

  The elastic modulus of the lower substrate 11 is preferably higher than that of the lower cladding layer 12. Since the elastic modulus of the lower substrate 11 is higher than the elastic modulus of the lower cladding layer 12, the warp of the entire optical waveguide can be reduced.

  The elastic modulus of the upper substrate 15 is preferably higher than that of the upper clad layer 14. Since the elastic modulus of the upper substrate 15 is higher than the elastic modulus of the upper clad layer 14, the warp of the entire optical waveguide can be reduced. Further, since the elastic modulus of the upper substrate 15 is higher than the elastic modulus of the upper cladding layer 14, burrs caused by deformation of the entire upper substrate 15 during processing can be reduced, and the upper cladding layer 14 has low elasticity. It is possible to reduce burrs in the upper clad layer 14 due to vibrations caused by processing.

  The difference in elastic modulus between the lower substrate 11 and the upper substrate 15 is preferably 0 Pa or more and 10 GPa or less, more preferably 0 Pa or more and 5 GPa or less, and more preferably 0 Pa or more and 3 GPa from the viewpoint of reducing warpage of the entire optical waveguide. More preferably, it is as follows.

The thickness of the lower substrate 11 and the upper substrate 15 is not particularly limited, but if it is 5 μm or more, there is an advantage that it is easy to obtain strength, and if it is 37.5 μm or less, there is an advantage that a low-profile optical waveguide can be obtained. is there. From the above viewpoint, the thickness of the lower substrate 11 and the upper substrate 15 is preferably in the range of 5 μm or more and 37.5 μm or less, and more preferably in the range of 10 μm or more and 25 μm or less. In particular, by setting the thickness of the upper substrate 15 to 10 μm or more and 25 μm or less, it is possible to reduce the burrs of the upper cladding layer 14 and reduce the amount of cutting, so that the optical path conversion mirror 19 can be formed satisfactorily.
The thickness of the upper substrate 15 with respect to the thickness of the lower substrate 11 is preferably 0.5 times or more and 2 times or less, and 0.7 times or more and 1.5 times from the viewpoint of reducing warpage of the entire optical waveguide. Or less, more preferably 0.8 times or more and 1.3 times or less.

It is preferable that the upper substrate 15 is provided at a place where at least the groove portion 17 is provided. By providing the upper substrate 15 at a location where the groove portion 17 is provided, it is possible to reduce burrs and warpage generated in the vicinity of the location where the groove portion 17 is formed due to pressurization or vibration when forming the groove portion 17.
In addition, the upper substrate 15 may be provided only in a portion where the groove portion 17 is provided, but is preferably provided on the entire surface of the upper cladding layer 14. By providing the upper substrate 15 on the entire surface of the upper clad layer 14, there is an effect of reducing burrs and warpage generated in the vicinity of the groove 17 formation site due to pressurization and vibration when forming the groove 17, and the entire optical waveguide This has the effect of reducing the warpage. Further, since the upper substrate 15 is provided on the entire surface of the upper clad layer 14, the thickness of the optical waveguide can be made uniform.

<Lower cladding layer and upper cladding layer>
The lower clad layer 12 and the upper clad layer 14 are not particularly limited as long as they have a refractive index lower than that of the core pattern 13 and are cured by heat or / and light, and a thermosetting resin or a photosensitive resin is preferably used. can do. The clad layer forming resins for forming the lower clad layer 12 and the upper clad layer 14 may contain the same or different components, and may have the same or different refractive indexes.
In the present invention, the lower clad layer 12 is a clad layer disposed at least between the core pattern 13 and the lower substrate 11, and the upper clad layer 14 is at least between the core pattern 13 and the upper substrate 15. This refers to the clad layer that is disposed. The clad layer formed on the same layer covering the side surface of the core pattern 13 is formed separately from the lower clad layer 12 and the upper clad layer 14 even if the clad layer is continuous from the lower clad layer 12 and the upper clad layer 14. It may be. In other words, the clad layer covering the side surface of the core pattern 13 may be the lower clad layer 12 or the upper clad layer 14 or may be a layer having a lower refractive index than the core pattern 13 different from them. .

  The thickness of the lower clad layer 12 and the upper clad layer 14 is not particularly limited, but is preferably in the range of 5 to 500 μm. 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. From the above viewpoint, the thicknesses of the lower cladding layer 12 and the upper cladding layer 14 are more preferably in the range of 5 to 100 μm.

<Core pattern>
The core pattern 13 is not particularly limited as long as it has a higher refractive index than the lower cladding layer 12 and the upper cladding layer 14 and is transparent to the extent that the optical signal used does not affect the transmission of the optical signal. It is preferable to use what can be converted. As an example of the patterning method, it can be formed by laminating a resin layer for forming the core pattern 13 on the lower clad layer 12, exposing it, and developing it if necessary. From the above viewpoint, the resin forming the core pattern 13 is preferably a photosensitive resin composition.

  The thickness of the core pattern 13 is not particularly limited. However, when the thickness after the pattern formation is 10 μm or more, the alignment tolerance can be increased in coupling with the light emitting / receiving element or the optical fiber after the optical waveguide is formed. In the case of 100 μm or less, there is an advantage that the coupling efficiency is improved in coupling with the light emitting / receiving element or the optical fiber after the optical waveguide is formed. From the above viewpoint, the thickness of the core pattern 13 is preferably in the range of 10 to 100 μm, and more preferably in the range of 30 to 90 μm.

<Groove>
The groove portion 17 is formed by a groove forming surface 18 formed by communicating the upper substrate 15, the upper clad layer 14, and the core pattern 13. At least a part of the groove forming surface 18 functions as an optical path conversion mirror 19 that performs optical path conversion of an optical signal passing through the core pattern 13. The optical path conversion mirror 19 is preferably an inclined surface of 30 ° or more and 60 ° or less having a function of converting an optical signal propagated through the core pattern 13 in a direction substantially perpendicular to the lower cladding layer 12 and the upper cladding layer 14. It is more preferable that the inclined surface is 35 degrees or more and 55 degrees or less. The optical path conversion mirror 19 may be an air reflecting mirror or a metal reflecting mirror in which a reflecting metal layer is formed on the groove forming surface 18.
As a specific example of forming the groove portion 17, it can be formed by cutting and removing the upper substrate 15, the upper cladding layer 14 and the core pattern 13 from the upper substrate 15 side using a dicing blade, laser ablation, or the like.
As a shape of the dicing blade, specifically, a portion corresponding to a depth at which the optical path conversion mirror 19 is formed when the groove portion 17 is formed is an inclined surface, and a depth at which the upper substrate 15 is formed when the groove portion 17 is formed. A part corresponding to this is a blade that is a vertical surface. Further, as a shape of the dicing blade, there is a blade in which one surface is an inclined surface and the other surface is a substantially vertical surface.

  The shape of the groove forming surface 18 other than the optical path conversion mirror 19 is not particularly limited, but if it has a surface steeper than the inclination angle of the optical path conversion mirror 19, the upper substrate 15 and the upper cladding layer to be removed by cutting are removed. Since the volume of 14 can be reduced, the processing efficiency is good and the smoothness of the surface of the optical path conversion mirror 19 can be improved, so that the optical path conversion mirror 19 with low light loss can be obtained. Furthermore, since the area of the part opened to the upper substrate 15 can be reduced, it is possible to contribute to the reduction of the adhesion of foreign matters and the like to the optical path conversion mirror 19 and the improvement of the strength of the optical path conversion mirror 19.

<Lid>
The optical waveguide of the present invention preferably further includes a lid 16 provided on the upper substrate 15 and covering the groove portion 17. By providing the lid 16 covering the groove portion 17 on the upper substrate 15, the strength of the optical waveguide in the groove portion 17 (optical path conversion mirror 19) can be improved. Further, by providing the lid 16 on the upper substrate 15, it is possible to prevent flying objects from adhering to the optical path conversion mirror 19. Even when the upper clad layer 14 is fragile, by providing the lid 16 on the upper substrate 15, the adhesiveness can be enhanced and the cohesive failure of the upper clad layer 14 can be suppressed.

The difference in elastic modulus between the upper substrate 15 and the lid 16 is preferably 0 Pa or more and 10 GPa or less, more preferably 0 Pa or more and 5 GPa or less, and more preferably 0 Pa or more and 3 GPa or less from the viewpoint of reducing warpage of the entire optical waveguide. More preferably.
The lid 16 may be the same material as the upper substrate 15 or a different material.

The thickness of the lid 16 is not particularly limited, but if it is 5 μm or more, there is an advantage that strength is easily obtained, and if it is 37.5 μm or less, there is an advantage that a low-profile optical waveguide can be obtained. From the above viewpoint, the thickness of the lid 16 is preferably in the range of 5 μm to 37.5 μmm, and more preferably in the range of 10 μm to 25 μmm.
The thickness of the lid 16 with respect to the thickness of the upper substrate 15 is preferably 0.5 times or more and 2 times or less, and 0.7 times or more and 1.5 times or less, from the viewpoint of reducing warpage of the entire optical waveguide. It is more preferable that it is 0.8 times or more and 1.3 times or less.

<Adhesive layer>
When there is no adhesive force between the upper clad layer 14 and the upper substrate 15, it is preferable to bond the upper clad layer 14 and the upper substrate 15 through the first adhesive layer 21.
When there is no adhesive force between the upper substrate 15 and the lid 16, it is preferable to bond the upper substrate 15 and the lid 16 through the second adhesive layer 22.
The thickness of the first adhesive layer 21 is more preferably equal to or less than the thickness of the upper substrate 15, more preferably 50% or less, and even more preferably 40% or less.
The thickness of the second adhesive layer 22 is preferably equal to or less than the thickness of the lid 16, more preferably 50% or less, and even more preferably 40% or less.
The distance between the core pattern 13 and the upper substrate 15 (the thickness of the upper cladding layer 14 or the sum of the thicknesses of the upper cladding layer 14 and the first adhesive layer 21) is compared with the thickness of the upper substrate 15. If it is 2 times or less, burrs of the upper clad layer 14 and interfacial peeling between the core pattern 13 and the upper clad layer 21 can be effectively suppressed, and it is more preferably 1 time or less.

[Optical Waveguide Manufacturing Method]
Below, the manufacturing method of the optical waveguide which concerns on embodiment of this invention is demonstrated using FIG.2 and FIG.3.

First, as shown in FIG. 2A, a lower clad layer 12 is preferably laminated on the lower substrate 11.
The method for forming the lower clad layer 12 is not particularly limited. For example, the resin varnish for forming the clad layer is directly applied from the formation surface side of the lower substrate 11 using a spin coater, die coater, comma coater, curtain coater, or the like. The method of apply | coating and hardening | curing suitably and making it the lower clad layer 12 is mentioned.
In the case of an optical waveguide that does not include the lower substrate 11, it can be formed, for example, by once forming a layer such as a lower cladding layer on the substrate and then peeling the substrate.

Next, as shown in FIG. 2B, a core forming resin layer 13 a is laminated on the lower cladding layer 12.
The method for laminating the core forming resin layer 13a on the lower cladding layer 12 is not particularly limited. For example, a core layer forming resin varnish or a core layer forming resin film is used, and a spin layer is formed on the lower cladding layer 12. Examples thereof include a method of directly applying using a coater, a die coater, a comma coater, a curtain coater, etc., and appropriately curing to form a core-forming resin layer 13a. As another method, a core-forming resin film formed by applying a core-forming resin varnish on a support film in advance, roll laminate, vacuum roll laminate, flat plate laminate, vacuum flat plate laminate, atmospheric pressure press, vacuum press, etc. And a method of laminating the core-forming resin layer 13a using the above.
The core-forming resin is preferably a photocurable resin, a thermosetting resin, or a light / heat combination curable resin from the viewpoint of fluidity during application and curing after lamination.

Next, as shown in FIG. 2 (c), the core forming resin layer 13 a is patterned to form the core pattern 13.
The method for forming the core pattern 13 is not particularly limited, and examples thereof include a method for forming the core pattern 13 in a desired shape by etching or the like after forming the core-forming resin layer 13a.
When the core forming resin layer 13a is a photosensitive resin, it can be patterned by photolithography, which is preferable. As specific photolithography processing, various solvents that can form uncured portions and cured portions in the core layer by exposure through a photomask on which a desired pattern shape is drawn, and dissolve and remove the uncured portions; Patterning can be performed by a developing process using a developing solution such as an alkaline solution.

Next, as shown in FIG. 2D, the upper clad layer 14 is laminated on the core pattern 13.
The method of forming the upper clad layer 14 is not particularly limited. For example, the clad layer forming resin varnish is directly applied from the formation surface side of the core pattern 13 using a spin coater, die coater, comma coater, curtain coater, or the like. The method of apply | coating and forming by the photolithographic process as mentioned above is mentioned. As another method, a clad layer forming resin film in which a clad layer forming resin varnish is previously coated on a support film is applied to a roll laminate, a vacuum roll laminate, a flat plate laminate, a vacuum flat plate laminate, an atmospheric pressure press, a vacuum press, etc. A method of stacking from the formation surface side of the core pattern 13 and forming the core pattern 13 by photolithography is also used. Moreover, as another method, the method of forming the resin varnish for clad layer formation by screen-printing and partially apply | coating to a desired location is mentioned.

Next, as shown in FIG. 3A, the upper substrate 15 is laminated on the upper clad layer 14.
The method of laminating the upper substrate 15 is not particularly limited. For example, a method of laminating the upper substrate 15 at a desired position after laminating the first adhesive layer 21 on the upper clad layer 14 can be mentioned.

  In the step of laminating the upper substrate 15, it is preferable that the upper substrate 15 be laminated at least where the groove portions 17 are provided. By stacking the upper substrate 15, burrs and warpage that occur in the vicinity of the location where the groove 17 is formed when the groove 17 is formed can be reduced.

  Alternatively, in the step of laminating the upper substrate 15, it is preferable to laminate the upper substrate 15 over the entire surface of the upper clad layer 14. Since the upper substrate 15 is provided on the entire surface of the upper clad layer 14, when the groove portion 17 is formed, burrs and warpage that occur in the vicinity of the groove portion 17 formation position can be reduced, and the warpage of the entire optical waveguide can be reduced. Can be made. Further, since the upper substrate 15 is provided on the entire surface of the upper clad layer 14, the thickness of the optical waveguide can be made uniform.

Next, as shown in FIG. 3B, the groove forming surface 18 is cut from the upper substrate 15 side and has a groove forming surface 18 formed by communicating the upper substrate 15, the upper cladding layer 14 and the core pattern 13. A groove portion 17 that functions as an optical path conversion mirror 19 that performs optical path conversion of an optical signal that passes through the core pattern 13 is formed.
The method for forming the groove portion 17 is not particularly limited, and for example, a method of cutting and removing the upper substrate 15, the upper cladding layer 14, and the core pattern 13 from the upper substrate 15 side using a dicing blade, laser ablation, or the like can be given. It is done. When the groove portion 17 is formed, if the amount to be removed by cutting is large, processing with a dicing blade is easy and preferable.

Next, as shown in FIG. 3C, after the step of forming the groove portion 17, a lid 16 that covers the groove portion 17 is laminated on the upper substrate 15.
The method of laminating the lid 16 is not particularly limited, and for example, a method of laminating the lid 16 after laminating the second adhesive layer 22 at a desired location on the upper substrate 15 can be mentioned.

  According to the optical waveguide and the method for manufacturing the optical waveguide according to the first embodiment of the present invention, it is possible to reduce the peeling between layers and the generation of burrs, and to reduce the warpage.

(Second Embodiment)
As shown in FIG. 4, the optical waveguide according to the second embodiment of the present invention has a groove forming surface 18 that forms the groove portion 17 as compared with the optical waveguide shown in the first embodiment. Different. 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.

The groove portion 17 is formed by a groove forming surface 18 formed by communicating the upper substrate 15, the upper clad layer 14, the core pattern 13, and the lower clad layer 12. At least a part of the groove forming surface 18 functions as an optical path conversion mirror 19 that performs optical path conversion of an optical signal passing through the core pattern 13. The optical path conversion mirror 19 is preferably an inclined surface of 30 ° or more and 60 ° or less having a function of converting an optical signal propagated through the core pattern 13 in a direction substantially perpendicular to the lower cladding layer 12 and the upper cladding layer 14. It is more preferable that the inclined surface is 35 degrees or more and 55 degrees or less. The optical path conversion mirror 19 may be an air reflecting mirror or a metal reflecting mirror in which a reflecting metal layer is formed on the groove forming surface 18.
As a specific example of forming the groove portion 17, it can be formed by cutting and removing the upper substrate 15, the upper clad layer 14, the core pattern 13 and the lower clad layer 12 from the upper substrate 15 side using a dicing blade, laser ablation, or the like. .

Even in the optical waveguide according to the second embodiment of the present invention, the same effect as that of the optical waveguide according to the first embodiment can be obtained.
Furthermore, according to the optical waveguide according to the second embodiment of the present invention, since the groove forming surface 18 communicates the lower clad layer 12 with the upper substrate 15, the entire surface of the core pattern 13 is surely optical path conversion mirror. 19 can function.

(Other embodiments)
As described above, the present invention has been described according to the embodiment. However, it should not be understood that the description and drawings constituting a part of this disclosure limit the present invention. From this disclosure, various alternative embodiments, examples and operational techniques should be apparent to those skilled in the art.

For example, in the first embodiment, photolithography processing is exemplified as a method for forming the core pattern 13.
The optical waveguide only needs to be composed of a core pattern of a high refractive index portion that propagates light and a low refractive index cladding layer surrounding the core pattern, and the substrate is arranged at least on the side on which the optical path conversion mirror 19 is formed. The same effect can be obtained.
As an optical waveguide capable of obtaining the same effect, for example, the lower cladding layer 12, a photosensitive layer in which a high refractive index region (core pattern) and a low refractive index region (cladding) are expressed by pattern exposure, and an upper cladding layer are sequentially formed. Examples include laminated optical waveguides. Further, there is an optical waveguide in which a core pattern 13 is formed on the lower clad layer 12 by intaglio or imprint, and an upper clad layer 14 that covers the side surface and the upper surface of the core pattern 13 is formed. Furthermore, there is an optical waveguide in which a concave portion is formed in the lower cladding layer, the concave portion is filled with a high refractive index material as a core pattern, and the upper refractive index material is covered with the upper cladding layer. Furthermore, an optical waveguide formed by injecting a core pattern forming material into an arbitrary shape in the cladding layer can be mentioned. That is, in the present invention, the optical waveguide as described above can be adopted, and the direction in which the optical path conversion mirror is processed may be on the side where the substrate is present in those optical waveguides.

  Thus, it should be understood that the present invention includes various embodiments and the like not described herein.

  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.

Example 1
<Fabrication of optical waveguide>
A lower clad layer 12 (Hitachi Chemical Co., Ltd.) is formed on the entire surface of a polyimide substrate (“Kapton EN” manufactured by Toray DuPont, thickness 25 μm, tensile elastic modulus 5.3 GPa, size 100 mm × 100 mm) as the lower substrate 11. Manufactured, having a thickness of 10 μm and a tensile elastic modulus of 0.7 MPa).
Next, four core patterns 13 (manufactured by Hitachi Chemical Co., Ltd., thickness 50 μm, width 50 μm, tensile elastic modulus 1.5 GPa) were formed on the lower clad layer 12 (250 μm pitch).
Next, the upper clad layer 14 (tensile modulus of 0.7 MPa) was laminated on the entire surface of the lower clad layer 12 so as to cover the side surfaces and the upper surface of the core pattern 13 and have a thickness of 10 μm on the core pattern 13.
Next, a thermosetting adhesive (manufactured by Hitachi Chemical Co., Ltd.) was applied on the entire surface of the upper clad layer 14, and a first adhesive layer 21 (thickness 10 μm, tensile elastic modulus 1 GPa) was laminated. On the laminated first adhesive layer 21, a polyimide substrate (“Kapton EN” manufactured by Toray DuPont Co., Ltd., thickness 25 μm, tensile elastic modulus 5.3 GPa) is arranged as the upper substrate 15, and the first adhesive layer 21. The upper clad layer 14 and the upper substrate 15 were bonded to each other to obtain an optical waveguide.

<Formation of mirror>
A dicing blade having a 90 ° opening (45 ° inclined surface) from the lid forming surface side of the obtained optical waveguide with a double-sided polyimide substrate was rotated at 30,000 rpm and the cutting speed was 3.0 mm / s, and the tip of the dicing blade was Then, cutting was performed so as to bite into the lower cladding layer 12.
As a result, there was no interface separation between the core pattern 13 and the upper clad layer 14, no burrs were generated in the upper clad layer 14, and no cutting foreign matter or the like was found on the cut surface. Moreover, the optical waveguide was not warped and could be handled well. The surface of the optical path conversion mirror 19 was less rough and good.

<Lamination of lid>
A thermosetting adhesive (manufactured by Hitachi Chemical Co., Ltd.) is applied to the portion of the upper substrate 15 where the optical path conversion mirror 19 (groove portion 17) is provided from the optical path conversion mirror processed surface side of the obtained optical waveguide with the optical path conversion mirror. Then, the second adhesive layer 22 (thickness 10 μm, tensile elastic modulus 1 GPa) was laminated. A polyimide substrate (manufactured by Toray DuPont, “Kapton EN”, thickness 25 μm, tensile elastic modulus 5.3 GPa, size 100 mm × 5 mm) was laminated on the laminated second adhesive layer 22.
Even when the optical waveguide with a mirror was bent with a curvature radius of 10 mm, the optical path conversion mirror 19 was not broken.

(Example 2)
In Example 1, the dicing blade was shaped in the same manner except that a 45 ° opening blade having one surface of 45 ° (on the optical path conversion mirror side) and the other surface being a vertical surface was used. As a result, no burrs were generated in the upper clad layer 14, and no cutting foreign matter or the like was found on the cutting surface. Moreover, the optical waveguide was not warped and could be handled well. The surface of the optical path conversion mirror 19 was less rough and good.
Furthermore, even when the lid 16 was laminated in the same manner as in Example 1 and the optical waveguide with a mirror was bent with a curvature radius of 10 mm, the optical path conversion mirror was not broken.

(Example 3)
In Example 1, the optical path was changed in the same manner except that the lower substrate 11 and the lid 16 were changed to a polyimide substrate (trade name “Kapton V”, thickness 25 μm, tensile elastic modulus 3.4 GPa, manufactured by Toray DuPont Co., Ltd.). An optical waveguide with a conversion mirror was produced. As a result, no burrs were generated in the upper clad layer 14, and no cutting foreign matter or the like was found on the cutting surface. In addition, the optical waveguide is less warped and can be handled well. The surface of the optical path conversion mirror 19 was less rough and good.
Furthermore, even if the optical waveguide with a mirror with the lid 16 was bent with a curvature radius of 10 mm, the optical path conversion mirror was not broken.

Example 4
In Example 1, an optical path conversion mirror is provided in the same manner except that the lower substrate 11 and the lid 16 are changed to a polyimide substrate (manufactured by Ube Industries, “Upilex S”, thickness 25 μm, tensile elastic modulus 9.1 GPa). An optical waveguide was produced. As a result, no burrs were generated in the upper clad layer 14, and no cutting foreign matter or the like was found on the cutting surface. In addition, the optical waveguide is less warped and can be handled well. The surface of the optical path conversion mirror 19 was less rough and good.
Furthermore, even if the optical waveguide with a mirror with the lid 16 was bent with a curvature radius of 10 mm, the optical path conversion mirror was not broken.

(Example 5)
In Example 1, an optical waveguide with an optical path conversion mirror was manufactured in the same manner except that the thickness of the polyimide used for the lower substrate 11 was changed to 12.5 μm. As a result, no burrs were generated in the upper clad layer 14, and no cutting foreign matter or the like was found on the cutting surface. In addition, the optical waveguide is less warped and can be handled well. The surface of the optical path conversion mirror 19 was less rough and good.
Furthermore, even if the optical waveguide with a mirror with the lid 16 was bent with a curvature radius of 10 mm, the optical path conversion mirror was not broken.

(Example 6)
In Example 1, an optical waveguide with an optical path conversion mirror was produced in the same manner except that the thickness of the polyimide used for the upper substrate 15 was changed to 12.5 μm. As a result, no burrs were generated in the upper clad layer 14, and no cutting foreign matter or the like was found on the cutting surface. In addition, the optical waveguide is less warped and can be handled well. The roughness of the surface of the optical path conversion mirror 19 was also substantially good.
Furthermore, even if the optical waveguide with a mirror with the lid 16 was bent with a curvature radius of 10 mm, the optical path conversion mirror was not broken.

(Example 7)
An optical waveguide with an optical path conversion mirror was produced in the same manner as in Example 1 except that the thickness of the polyimide used for the lid 16 was changed to 12.5 μm. As a result, no burrs were generated in the upper clad layer 14, and no cutting foreign matter or the like was found on the cutting surface. In addition, the optical waveguide is less warped and can be handled well. The surface of the optical path conversion mirror 19 was less rough and good.
Furthermore, even if the optical waveguide with a mirror with the lid 16 was bent with a curvature radius of 10 mm, the optical path conversion mirror was not broken.

(Example 8)
In Example 1, an optical waveguide with an optical path conversion mirror was produced in the same manner except that the upper substrate 12 was partially laminated on the cutting position (size 100 mm × 7 mm). As a result, no burrs were generated in the upper clad layer 14, and no cutting foreign matter or the like was found on the cutting surface. Further, although there was some warping of the optical waveguide at the time of cutting, there was no warping of the cutting part, and it was possible to handle well and processing was possible. The surface of the optical path conversion mirror 19 was less rough and good.
Furthermore, even if the optical waveguide with a mirror with the lid 16 was bent with a curvature radius of 10 mm, the optical path conversion mirror was not broken.

Example 9
In the first embodiment, the optical path conversion mirror is formed in the same manner except that the optical path conversion mirror 19 is formed by cutting from the lower substrate 11 side so as to bite into the upper clad layer 14 between the core pattern 13 and the upper substrate 15. An attached optical waveguide was produced. In this case, the lower substrate 11 in Example 1 is regarded as the upper substrate 15, the lower cladding layer 12 as the upper cladding layer 14, the upper cladding layer 14 as the lower cladding layer 12, and the upper substrate 15 as the lower substrate 11. Thereafter, the lid 16 (size 100 mm × 5 mm) used in Example 1 was laminated from the lower substrate 11 side. As a result, no burrs were generated in the upper clad layer 14 (the upper substrate in Example 1), and there was no cutting foreign matter or the like on the cutting surface. Further, there was no warping of the optical waveguide during the cutting process, and it was possible to handle it satisfactorily. The surface of the optical path conversion mirror 19 was less rough and good.
Furthermore, even if the optical waveguide with a mirror with the lid 16 was bent with a curvature radius of 10 mm, the optical path conversion mirror was not broken.

(Comparative Example 1)
In Example 1, when the upper substrate 15 was not laminated and cutting was performed from the upper clad layer 14 side in the same manner as in Example 1, peeling was observed between the core pattern 13 and the upper clad layer 14, Burrs were generated in the upper clad layer 14. Further, the warp of the optical waveguide is large, and handling is difficult at the time of cutting.
Furthermore, when the lid 16 is laminated on the upper clad layer 14 and the optical waveguide with a mirror is bent at a radius of curvature of 10 mm as in the first embodiment, the upper clad layer 14 is coherently broken and broken at the groove portion 17 (mirror portion). There was a thing.

  Since the optical waveguide of the present invention can perform stable optical transmission and can be used for an optical device, it can be applied to a wide range of fields such as various optical devices and optical interconnections.

DESCRIPTION OF SYMBOLS 11 ... Lower board | substrate 12 ... Lower clad layer 13 ... Core pattern 14 ... Upper clad layer 15 ... Upper board | substrate 16 ... Cover 17 ... Groove part 18 ... Groove formation surface 19 ... Optical path conversion mirror 21 ... 1st adhesive layer 22 ... 2nd adhesive layer

Claims (18)

A lower cladding layer;
A core pattern provided on the lower cladding layer;
An upper clad layer provided on the core pattern;
An upper substrate provided on the upper cladding layer;
As an optical path conversion mirror which has a groove forming surface formed by communicating the upper substrate, the upper clad layer and the core pattern, and at least a part of the groove forming surface performs optical path conversion of an optical signal passing through the core pattern. An optical waveguide provided with a functioning groove.   The optical waveguide according to claim 1, wherein the lower cladding layer is provided on a lower substrate.   The optical waveguide according to claim 1, wherein the upper substrate is provided at a place where at least the groove is provided.   The optical waveguide according to claim 1, wherein the upper substrate is provided on the entire surface of the upper cladding layer.   The optical waveguide according to claim 1, further comprising a lid provided on the upper substrate and covering the groove.   The optical waveguide according to claim 1, wherein an elastic modulus of the upper substrate is higher than an elastic modulus of the upper clad layer.   The optical waveguide according to claim 2, wherein a difference in elastic modulus between the lower substrate and the upper substrate is 0 Pa or more and 10 GPa or less.   The optical waveguide according to claim 5, wherein a difference in elastic modulus between the upper substrate and the lid is 0 Pa or more and 10 GPa or less.   The optical waveguide according to claim 2, wherein a thickness of the upper substrate with respect to a thickness of the lower substrate is not less than 0.5 times and not more than twice.   The optical waveguide according to claim 5, wherein a thickness of the lid with respect to a thickness of the upper substrate is not less than 0.5 times and not more than 2 times.   The optical waveguide according to claim 1, wherein the groove forming surface communicates the upper substrate, the upper cladding layer, the core pattern, and the lower cladding layer.   The optical waveguide according to claim 2, wherein the lower substrate and the upper substrate are mainly composed of polyimide. Forming a laminate comprising a lower cladding layer, a core pattern, an upper cladding layer, and an upper substrate;
An optical signal that has a groove forming surface that is cut from the upper substrate side and that communicates the upper substrate, the upper cladding layer, and the core pattern, and at least a part of the groove forming surface passes through the core pattern. Forming a groove functioning as an optical path conversion mirror for performing optical path conversion. The method of manufacturing an optical waveguide according to claim 13, wherein the step of forming the laminated body is a step of forming the laminated body on a lower substrate.   15. The method of manufacturing an optical waveguide according to claim 13, wherein the step of laminating the upper substrate includes laminating the upper substrate at least at a location where the groove is provided.   The method of manufacturing an optical waveguide according to claim 13, wherein in the step of stacking the upper substrate, the upper substrate is stacked on the entire surface of the upper clad layer.   The method for manufacturing an optical waveguide according to claim 13, wherein a lid that covers the groove is laminated on the upper substrate after the step of forming the groove.   The method for manufacturing an optical waveguide according to claim 13, wherein the step of forming the groove portion forms the groove portion by processing with a dicing blade.