JP5934932B2 - Optical waveguide, photoelectric composite wiring board, and method for manufacturing optical waveguide - Google Patents

Description

  The present invention relates to an optical waveguide, an optoelectric composite wiring board including the optical waveguide, and a method for manufacturing the optical waveguide.

  High-speed transmission is required in the field of medium- and long-distance communication, specifically in the field of FTTH (Fiber To The Home) and in-vehicle, and in order to realize this, an optical fiber cable is used as a transmission medium. Has been.

  High-speed transmission has been demanded even in short-distance communication, for example, communication within 1 m. Also, in the field of such short distance communication, performance that is difficult to achieve with optical fiber cables is also required. Specifically, the required performance includes high-density wiring such as narrow pitch, branching, crossing, and multilayering, surface mountability, integration with an electric circuit board, and a small radius of curvature. For example, it can be bent. As a basis for satisfying these requirements, it is conceivable to use an optical wiring board having an optical waveguide.

  In addition, in such an optical wiring board, a light emitting element such as a vertical cavity surface emitting laser (VCSEL), a light receiving element such as a photodiode (PD), A semiconductor element such as an integrated circuit (IC) is preferably mounted. In order to drive these elements, an electric circuit needs to be provided on the optical wiring board or the like. From this, it is preferable that the photoelectric composite wiring board is provided with not only an optical waveguide but also an electric circuit.

  In such an opto-electric composite wiring board, the light guided in the optical waveguide is bent at a desired angle, for example, for the purpose of inputting light into the optical waveguide or outputting light from the optical waveguide. An inclined surface capable of reflecting light is formed in the core portion of the optical waveguide. And in order to raise the reflectance of the light in the inclined surface, a metal layer may be formed in an inclined surface.

  As a method for forming a metal layer on an inclined surface in an optical waveguide, for example, a method for producing an optical waveguide with a mirror described in Patent Document 1 can be cited.

  Patent Document 1 discloses a method of manufacturing an optical waveguide with a mirror having a slope on a core of an optical waveguide and having a metal film on the slope, and deposits metal on a metal film transfer jig, and A mirror that attaches an adhesive having the same refractive index as the core and applies the metal of the metal film transfer jig to the slope with the adhesive to transfer the metal to form a metal film on the slope. A method for manufacturing an attached optical waveguide is described.

JP 2008-304615 A

  When manufacturing an optical waveguide, when a metal layer is formed by a so-called transfer method, in which a metal layer is attached to the inclined surface of the core portion, the metal layer goes around the side surface of the core portion beyond the inclined surface of the core portion. In some cases, it was formed. When the metal layer wraps around the side surface of the core portion in this way, the pressure applied when the metal layer is attached to the inclined surface is not easily applied to the entire inclined surface. As a result, the loss in reflection of light at the metal layer may increase. Further, the metal layer wraps around easily when the distance between adjacent core portions is large. For this reason, it is conceivable to reduce the distance between the core portions. However, if the distance between the core parts is reduced, it becomes difficult to form the core parts, or the clad layer existing between the core parts becomes thin, and the light reflectance between the core parts and the clad layers is reduced. There was a risk of the decrease.

  This invention is made | formed in view of this situation, Comprising: It aims at providing the manufacturing method of the optical waveguide which can form the metal layer in which the loss in the reflection of light was reduced on the inclined surface. It is another object of the present invention to provide an optical waveguide capable of forming a metal layer with reduced loss in light reflection on an inclined surface. It is another object of the present invention to provide a photoelectric composite wiring board provided with the optical waveguide.

  An optical waveguide manufacturing method according to an aspect of the present invention includes: an elongated core portion; and an auxiliary portion arranged in parallel with a predetermined interval in the width direction of the core portion on the surface of the first cladding layer. Forming a core part, forming an inclined surface for reflecting light on the core part, and forming a metal layer on the inclined surface by a transfer method. A clad layer forming step of forming a clad layer covering the core portion by forming a second clad layer so as to embed the core portion and the auxiliary portion formed on the first clad layer, The inclined surface forming step is a step of forming the inclined surface in the core portion and processing so that one end surface of the auxiliary portion is adjacent to the inclined surface. It is a manufacturing method.

  In the method for manufacturing an optical waveguide, the inclined surface forming step is preferably a step in which an end surface of the auxiliary portion forms an inclined surface that is substantially on the same plane as the inclined surface.

  Moreover, in the manufacturing method of the optical waveguide, it is preferable that a distance between the core portion and the auxiliary portion is 10 to 50 μm.

  Moreover, in the manufacturing method of the optical waveguide, the inclined surface forming step forms the inclined surface in the core portion, and is opposed to the inclined surface of the core portion and spaced apart from the core portion. It is the process of forming a part, It is preferable that the height of the said opposing part is more than half of the height of the said core part.

  In the optical waveguide manufacturing method, the surface of the facing portion that faces the inclined surface is a surface inclined in a direction opposite to the inclination of the inclined surface, and the core portion and the facing portion The distance is preferably 10 to 100 μm at the nearest place.

  An optical waveguide according to another aspect of the present invention includes a long core portion and a clad layer covering the core portion, and each core portion has an inclined surface for reflecting light. The optical waveguide further includes an auxiliary portion arranged in parallel with a predetermined interval in the width direction of the core portion so that one end surface is adjacent to the inclined surface.

  In the optical waveguide, it is preferable that one end surface of the auxiliary portion located adjacent to the inclined surface is substantially on the same surface as the inclined surface.

  The optical waveguide preferably includes a metal layer on the inclined surface.

  The optical waveguide further includes a facing portion facing the inclined surface of the core portion and spaced apart from the core portion, wherein the height of the facing portion is at least half the height of the core portion. It is preferable that

  An opto-electric composite wiring board according to another aspect of the present invention is an opto-electric composite wiring board including the optical waveguide and the electric wiring board.

  ADVANTAGE OF THE INVENTION According to this invention, the optical waveguide which can form the metal layer in which the loss in reflection of light was reduced on an inclined surface can be provided. An optoelectric composite wiring board provided with the optical waveguide is also provided. Moreover, the manufacturing method of the optical waveguide which can form the metal layer in which the loss in reflection of light was reduced on an inclined surface can be provided.

It is the schematic which shows a part of optical waveguide manufactured by the manufacturing method which concerns on one Embodiment of this invention. FIG. 2 is an enlarged view of a portion surrounded by a broken line 15 in FIG. 1. Sectional drawing of an example of the laminated | multilayer film used by embodiment of this invention is shown. It is the schematic which shows a part of optical waveguide manufactured by the manufacturing method which concerns on other one Embodiment of this invention. It is the schematic which shows a part of conventional optical waveguide. 6 is a schematic diagram for explaining a method of manufacturing an optical waveguide according to Example 1. FIG. It is drawing for demonstrating the start time of the inclined surface formation in a core part in Example 1. FIG. It is drawing for demonstrating after formation of the inclined surface to a core part in Example 1. FIG. 6 is a schematic diagram for explaining a method of manufacturing an optical waveguide according to Example 2. FIG. It is a schematic diagram for demonstrating the manufacturing method of the optical waveguide which concerns on a comparative example. It is drawing for demonstrating the start time of the inclined surface formation to a core part in a comparative example. It is drawing for demonstrating after formation of the inclined surface to a core part in a comparative example.

  Embodiments according to the present invention will be described below.

  In the method for manufacturing an optical waveguide according to an embodiment of the present invention, a long core portion and an auxiliary portion arranged in parallel at a predetermined interval in the width direction of the core portion are provided on the surface of the first cladding layer. A core portion forming step to be formed thereon, an inclined surface forming step of forming an inclined surface for reflecting light on the core portion, and a metal layer forming step of forming a metal layer on the inclined surface by a transfer method And a cladding layer forming step of forming a cladding layer covering the core portion by forming the second cladding layer so as to embed the core portion and the auxiliary portion formed on the first cladding layer. The inclined surface forming step is a step of forming the inclined surface in the core portion and processing so that one end surface of the auxiliary portion is adjacent to the inclined surface. It is a manufacturing method of a waveguide. Specifically, a method of manufacturing an optical waveguide as shown in FIG. That is, the optical waveguide manufactured here includes a long core portion and a clad layer covering the core portion, and each core portion has an inclined surface for reflecting light. The optical waveguide further includes an auxiliary portion arranged in parallel at a predetermined interval in the width direction of the core portion so that the end surface is adjacent to the inclined surface. Moreover, the manufacturing method of an optical waveguide will not be specifically limited if said process is provided, A specific manufacturing method is demonstrated in detail by the following Example. FIG. 1 is a schematic view showing a part of an optical waveguide manufactured by a manufacturing method according to an embodiment of the present invention. Fig.1 (a) is a side view which shows a part of optical waveguide seen from the side surface side of the elongate core part. FIG. 1B is a plan view showing a part of the optical waveguide viewed from the core side.

  An optical waveguide 10 manufactured by a manufacturing method according to an embodiment of the present invention first includes a long core portion 11 as shown in FIG. The optical waveguide 10 includes a clad layer that covers the core portion 11. Note that the optical waveguide actually includes a core portion and a cladding layer covering the core portion as described above. The clad layer includes, for example, a first clad layer (lower clad layer) having a core portion formed on the surface and a second clad layer (upper clad layer) formed so as to bury the core portion. And the like. However, in FIG. 1, in order to explain the characteristics of the present embodiment, a part of the cladding layer is omitted, and the core part is not covered with the cladding layer. Specifically, FIG. 1 shows only the first cladding layer 12 as the cladding layer and omits the second cladding layer.

  In addition, the optical waveguide 10 is illustrated in FIG. 1 as having two core parts. However, the optical waveguide 10 is not particularly limited as long as it has the above-described configuration. It may be.

  Moreover, the optical waveguide 10 has the inclined surface 11a for the elongate core part 11 to reflect light. In addition to the core portion 11 and the cladding layer, the optical waveguide 10 includes an auxiliary portion 13 that is arranged in parallel at a predetermined interval in the width direction of the core portion 11. The auxiliary portion 13 is provided so that one end surface 13 a thereof is adjacent to the inclined surface 11 a of the core portion 11. And the auxiliary | assistant part 13 is provided in the core part 11 with the predetermined space | interval D1. Further, when there are two or more core portions 11, the auxiliary portion 13 is interposed between the adjacent core portions 11. And the auxiliary | assistant part 13 is provided in the adjoining core part 11 with the predetermined space | interval D1.

  Moreover, on the inclined surface 11a of the core part 11, the metal layer 17 is provided as shown in FIG. By doing so, the reflectance of light can be increased and the loss of light due to the reflection of light on the inclined surface can be suppressed. 2 is an enlarged view of a portion surrounded by a broken line 15 in FIG. Moreover, the metal layer 17 may be directly formed on the inclined surface 11a of the core part 11, and may be formed through the adhesive bond layer 16, as shown in FIG. By doing so, the adhesiveness of the metal layer 17 can be improved. Moreover, the metal layer 17 will not be specifically limited if the reflectance of light can be raised. For example, a layer made of copper can be used.

  An example of the method for forming the metal layer 17 is a transfer method. More specifically, as shown in FIG. 3, a method of forming using a laminated film 19 in which an adhesive layer 16, a metal layer 17, and a base material 18 are laminated in this order can be mentioned. FIG. 3 shows a cross-sectional view of an example of a laminated film used when forming a metal layer on the inclined surface of the core part in the optical waveguide according to the embodiment of the present invention. After the adhesive layer 16 of the laminated film 19 is placed so as to be in contact with the inclined surface 11a of the core portion 11, it is pressed from the substrate 18 side of the laminated film 19 toward the inclined surface 11a. At that time, there is a method of applying pressure by applying a pressure head whose tip is made of an elastic material to the base material 18 side of the laminated film 19. Examples of the elastic material include silicone rubber. In addition, the laminated film may be provided with a release layer between the metal layer 17 and the substrate 18 in order to improve the release property of the metal layer. Moreover, it does not specifically limit as a laminated | multilayer film, For example, TCU3000 etc. by Thermal Printer Laboratory Co., Ltd. are mentioned.

  If it is a method of manufacturing such an optical waveguide, the obtained optical waveguide is obtained by forming a metal layer with reduced loss in light reflection on the inclined surface of the core portion. This is because an inclined surface for reflecting light is formed in the core portion, and the metal layer is formed on the inclined surface by attaching a metal layer to the inclined surface of the core portion as described above, for example. It is considered that the metal layer wrapping around the side surface of the core part that can occur at the time can be suppressed by the auxiliary part arranged in parallel with the core part. Accordingly, it is considered that the metal layer can be uniformly pressurized when being attached to the inclined surface. Therefore, it is considered that a metal layer with reduced loss in light reflection can be formed.

  Moreover, the auxiliary | assistant part 13 will not be specifically limited if the end surface 13a is arrange | positioned in the position adjacent to the inclined surface 11a of the core part 11. FIG. With such an auxiliary portion 13, it is considered that the metal layer can be prevented from wrapping around the side surface of the core portion. Moreover, it is preferable that the one end surface of the auxiliary portion 13 located adjacent to the inclined surface 11 a is substantially on the same plane as the inclined surface 11 a of the core portion 11. That is, it is preferable that the one end surface 13a of the auxiliary portion 13 located adjacent to the inclined surface 11a is an inclined surface inclined at substantially the same angle as the inclined surface 11a of the core portion 11. By doing so, it is considered that the above-described wraparound of the metal layer can be further suppressed, and a metal layer in which loss in light reflection is further reduced can be formed.

  Moreover, the material of the auxiliary | assistant part 13 may be the same as the material which comprises the core part 11, and may differ. In the case of different materials, any material having a lower refractive index than the core 11 can function as a cladding. Even if the distance D1 between the auxiliary portion 13 and the core portion 11 is narrow, it is possible to suppress a decrease in reflectance at the interface between the core portion 11 and the cladding layer of light guided through the core portion 11. Therefore, a reduction in light loss can be suppressed. Moreover, the space | interval D1 between the auxiliary | assistant part 13 and the core part 11 is so preferable that it is narrow. It is considered that the inclined surface 11a of the core portion 11 and the inclined surface 13a of the auxiliary portion 13 are approximated to a continuous surface, and the wraparound of the metal layer can be further suppressed, and the loss in light reflection is further reduced. A metal layer can be formed.

  Moreover, it is preferable that the space | interval D1 between the auxiliary | assistant part 13 and the core part 11 is 10-50 micrometers, It is more preferable that it is 15-40 micrometers, It is further more preferable that it is 20-30 micrometers. When the distance D1 is too small, the light guided through the core part 11 has a tendency that the reflectance at the interface between the core part 11 and the clad layer decreases and passes through the clad layer. That is, there is a tendency that loss of light guided through the core portion 11 due to radiation toward the auxiliary portion 13 side occurs. Thereby, even if the material of the auxiliary portion 13 is the same as the material constituting the core portion 11, the reflectance of the light guided through the core portion 11 is reduced at the interface between the core portion 11 and the cladding layer. It is thought that it can be suppressed. Moreover, when the space | interval D1 is too large, there exists a tendency for the effect which suppresses the wraparound of the metal layer to the core part side surface to reduce.

  The optical waveguide manufacturing method is a method in which, in the above-described manufacturing method, when the inclined surface is formed in the core portion, an opposing portion that faces the inclined surface of the core portion and is spaced apart from the core portion is also formed. A method of forming the facing portion may be preferable. Specifically, a method of manufacturing an optical waveguide as shown in FIG. In other words, the optical waveguide 20 manufactured here is an optical waveguide similar to the optical waveguide 10, as shown in FIG. 4, facing the inclined surface 11 a of the core portion 11 and facing away from the core portion 11. The unit 24 is further provided. FIG. 4 is a schematic view showing a part of an optical waveguide manufactured by a manufacturing method according to another embodiment of the present invention. FIG. 4A is a side view showing a part of the optical waveguide viewed from the side of the long core portion. FIG. 4B is a plan view showing a part of the optical waveguide viewed from the core side.

  By forming such a facing portion, an optical waveguide in which a metal layer with a reduced loss in light reflection is formed on the inclined surface of the core portion is obtained. This suppresses the member subjected to the pressurization from being displaced in the surface direction of the cladding layer or the like when the metal layer 17 is pressed in order to attach the metal layer 17 to the inclined surface 11a of the core portion 11. It is thought that it is possible. In other words, it is considered that the metal layer 17 can be uniformly pressurized when formed.

  In addition, the height of the facing portion 24 is preferably at least half of the height of the core portion 11. By doing so, it is possible to suitably suppress the occurrence of a shift in the surface direction of the cladding layer of the member subjected to pressurization when pressurizing the metal layer 17, and when forming the metal layer 17, It is thought that it can pressurize more uniformly. If the facing portion 24 is too low, it tends to be difficult to exhibit the suppression of the occurrence of the shift due to the presence of the facing portion.

  Moreover, it is preferable that the surface which opposes the inclined surface 11a of the core part 11 of the opposing part 24 is the surface 24a inclined in the opposite direction to the inclination of the inclined surface 11a. And it is preferable that it is 5-100 micrometers in the space | interval D2 of the core part 11 and the opposing part 24, and it is more preferable that it is 10-60 micrometers, and it is further more preferable that it is 10-30 micrometers. If the distance D is too narrow, the member subjected to pressurization when the metal layer 17 is pressurized tends to hardly reach the first cladding layer 12. Therefore, it becomes difficult to press the portion near the first cladding layer 12 on the inclined surface of the core portion 11, and it tends to be difficult to press the metal layer 17 uniformly. On the other hand, if the distance D2 is too large, it tends to be difficult to suppress the occurrence of the shift due to the presence of the facing portion.

  Further, the material of the facing portion 24 may be the same as or different from the material constituting the core portion 11.

  Next, a conventional optical waveguide will be described as a comparative embodiment for comparison with the embodiment according to the present invention.

  This comparative embodiment is the same as the embodiment according to the present invention except that the auxiliary portion 13 is not provided. Specifically, there is an optical waveguide 30 as shown in FIG. FIG. 5 is a schematic view showing a part of a conventional optical waveguide. Fig.5 (a) is a side view which shows a part of optical waveguide seen from the side surface side of the elongate core part. FIG. 5B is a plan view showing a part of the optical waveguide viewed from the core side.

  With such an optical waveguide 30, the distance between the adjacent core portions 11 is long, and when the metal layer is attached to the inclined surface 11 a of the core portion 11, the metal layer wraps around the side surface of the core portion 11. For this reason, a uniform metal layer cannot be formed on the inclined surface 11a. Further, if the distance between the core portions 11 is simply shortened, it is difficult to suppress a decrease in reflectance at the interface between the core portion 11 and the cladding layer of light guided through the core portion 11.

  On the other hand, in the case of the optical waveguide according to the embodiment of the present invention, as described above, the metal layer with reduced loss in light reflection is inclined without changing the distance between the core portions. Can be formed.

  In addition, an optoelectric composite wiring board according to another embodiment of the present invention includes the optical waveguide and the electric wiring board. The photoelectric composite wiring board is not particularly limited as long as it includes the optical waveguide and the electrical wiring board. Specifically, an optical / electrical composite wiring board is obtained by forming the optical waveguide on an electric wiring board on which an electric circuit is previously formed. An optical / electrical composite wiring board can also be obtained by attaching the optical waveguide and an electric wiring board on which an electric circuit is formed in advance.

  Moreover, as an electrical wiring board, if it is a board | substrate with which the electrical circuit was formed, it will not specifically limit. The substrate may be a flexible substrate or a rigid substrate.

  Hereinafter, the present invention will be described more specifically with reference to examples. The scope of the present invention is not limited by the examples.

  First, a method for producing the resin film used in this example will be described.

(Manufacture of resin film for lower cladding layer)
7 parts by mass of polypropylene glycol glycidyl ether (“PG207” manufactured by Nippon Steel Chemical Co., Ltd.), 25 parts by mass of liquid hydrogenated bisphenol A type epoxy resin (“YX8000” manufactured by Mitsubishi Chemical Corporation), solid hydrogenated bisphenol Type A epoxy resin (“YL7170” manufactured by Mitsubishi Chemical Corporation), 20 parts by mass, 1,2-epoxy-4- (2-oxiranyl) cyclohexane adduct of 2,2-bis (hydroxymethyl) -1-butanol ( 8 parts by mass of “EHPE3150” manufactured by Daicel Corporation, 2 parts by mass of solid bisphenol A type epoxy resin (“Epicoat 1006FS” manufactured by Mitsubishi Chemical Corporation), and phenoxy resin (“YP50” manufactured by Nippon Steel Chemical Co., Ltd.) 20 parts by mass, photocationic curing initiator (“SP170” manufactured by ADEKA Corporation) 0.5 1 part by weight, 0.5 parts by weight of a thermal cation curing initiator (“SI-150L” manufactured by Sanshin Chemical Industry Co., Ltd.) and 0.1 parts by weight of a surface conditioner (“F470” manufactured by DIC Corporation) The component was dissolved in a solvent of 30 parts by mass of toluene and 70 parts by mass of methyl ethyl ketone (MEK), filtered through a membrane filter having a pore size of 1 μm, and then degassed under reduced pressure to prepare an epoxy resin varnish. This epoxy resin varnish was applied onto a PET film (“A4100” manufactured by Toyobo Co., Ltd.) using a multicoater of a comma coater head manufactured by Hirano Technoseed Co., Ltd., and the coated film was dried. By doing so, the resin film for lower clad layers of predetermined thickness was obtained. The lower clad layer resin film thus obtained had a thickness of 15 μm. Moreover, the refractive index with respect to the light of wavelength 579nm of the resin film for lower clad layers was 1.54. This lower clad layer resin film was covered with an OPP film as a protective film.

(Manufacture of resin film for core part)
3,4-epoxycyclohexenylmethyl-3 ′, 4′-epoxycyclohexene carboxylate (“Celoxide 2021P (also referred to as CEL2021P)” manufactured by Daicel Corporation) 8 parts by mass, epoxy resin (“EHPE3150” manufactured by Daicel Corporation) 1,2-epoxy-4- (2-oxiranyl) cyclosoxane adduct of 2,2-bis (hydroxymethyl) -1-butanol), 12 parts by mass of solid bisphenol A type epoxy resin (manufactured by Mitsubishi Chemical Corporation) "Epicoat 1006FS") 37 parts by mass, trifunctional epoxy resin ("VG-3101" manufactured by Mitsui Chemicals, Inc.) 15 parts by mass, solid novolac epoxy resin ("EPPN201" manufactured by Nippon Kayaku Co., Ltd.) 18 parts by mass , Liquid bisphenol A type epoxy resin ("DIC Corporation" Each composition of 10 parts by mass of Piclon 850s "), 1 part by mass of a cationic photocuring initiator (" SP-170 "manufactured by ADEKA Corporation), and 0.1 part by mass of a surface conditioner (" F470 "manufactured by DIC Corporation). The component was dissolved in a mixed solvent of 30 parts by mass of toluene and 70 parts by mass of MEK. Then, the solution was filtered through a membrane filter having a pore size of 1 μm, and then degassed under reduced pressure to prepare an epoxy resin varnish. This epoxy resin varnish was applied onto a PET film (“A4100” manufactured by Toyobo Co., Ltd.) using a multicoater of a comma coater head manufactured by Hirano Technoseed Co., Ltd., and the coated film was dried. By doing so, the resin film for core parts of predetermined thickness was obtained. The core portion resin film thus obtained had a thickness of 40 μm. Moreover, the refractive index with respect to the light of wavelength 579nm of the resin film for core parts was 1.59. Moreover, the transmittance | permeability with respect to the light of wavelength 850nm of the resin film for core parts is 0.06 dB / cm, and the resin film for core parts had sufficient transparency.

(Manufacture of resin film for upper cladding layer)
An upper clad layer resin film was produced in the same manner as the upper clad layer resin film except that the thickness was changed to 40 μm.

(Manufacture of transfer film)
Instead of 1 part by mass of the cationic photocuring initiator (“SP-170” manufactured by ADEKA Corporation), the thermal cationic curing initiator (“SI-150L” manufactured by Sanshin Chemical Industry Co., Ltd.) was changed to 1 part by mass. Except for the above, a resin varnish for the adhesive layer was prepared in the same manner as the method for preparing the epoxy resin varnish used for the resin film for the core part. Although this resin varnish was used to form a film in the same manner as the core portion resin film, the refractive index for light with a wavelength of 579 nm was 1.59, and the transmittance for light with a wavelength of 850 nm was 0.00. It was 06 dB / cm. The film obtained using the resin varnish for the adhesive layer was found to have the same refractive index and transmittance as the core part.

  Next, a polyimide film having a thickness of 25 μm (“Kapton 100H” manufactured by Toray DuPont Co., Ltd.) was prepared and cut into a size of 100 mm × 100 mm. A film having a two-layer structure was obtained by forming a copper thin film on one side of the polyimide film obtained by cutting by vacuum sputtering. The thickness of the formed thin film is 1500 mm. On the surface on the thin layer side of the obtained film, the resin varnish for the adhesive layer is applied with a bar coater, subjected to primary drying at 80 ° C. for 10 minutes, and then at 120 ° C. for 10 minutes. Dried. By doing so, an adhesive layer was formed, and a laminated film as shown in FIG. 3 was obtained.

Example 1
Example 1 will be described with reference to FIG. FIG. 6 is a schematic diagram for explaining the method of manufacturing the optical waveguide according to the first embodiment.

  First, as shown in FIG. 6A, a polycarbonate substrate of 140 mm × 140 mm × thickness 1 mm was prepared as the substrate 61.

  Next, the OPP film is peeled from the lower clad layer resin film, and the lower clad layer resin film is placed on the substrate 61 as shown in FIG. A resin film for the lower clad layer was laminated on the substrate 61 by applying pressure for 120 seconds under the pressing condition. Thereafter, the surface of the resin film for the lower cladding layer was irradiated with 2000 mJ of ultraviolet light having a wavelength of 365 nm with an ultrahigh pressure mercury lamp. As a result, as shown in FIG. 6B, the lower clad layer resin film was cured, and a first clad layer (lower clad layer) 62 was formed on the substrate 61.

  Next, as shown in FIG.6 (c), the resin film for core parts is mounted on the surface of the lower clad layer 62, and it pressurizes for 120 second on 60 degreeC and 0.2 MPa pressurization conditions. The core material layer was formed by laminating the core portion resin film on the lower clad layer 62.

  Then, as shown in FIG. 6C, a photomask 64 having a linear pattern of slits is used, and the ultrahigh pressure adjusted so that the irradiation light becomes substantially parallel light on the core material layer through the mask. With a mercury lamp, ultraviolet light having a wavelength of 365 nm was irradiated with a light amount of 2000 mJ. By doing so, the location corresponding to the core portion of the core material layer was cured. As the photomask 64 used here, a photomask capable of forming the core portion 65 and the auxiliary portion 76 shown in FIG. 7 was used. Specifically, the one provided with the core part forming slit and the auxiliary part forming slit was used. Further, 20 core part forming slits were arranged. The auxiliary portion forming slits are disposed between the core portion forming slits and on both outer sides of the core portion forming slit, and are disposed at both ends of the core portion forming slit. Therefore, 42 auxiliary portion forming slits were arranged. And as a slit for core part formation, it was a slit of a linear pattern of width 40micrometer and length 110mm. The auxiliary portion forming slit was a slit having a width of 150 μm. The distance between the core part forming slit and the auxiliary part forming slit was 30 μm.

  Next, a phenomenon treatment was performed using an aqueous cleaning agent (“Clean Through” manufactured by Kao Corporation), which is a freon replacement cleaning liquid. By doing so, the core part 65 as shown in FIG.6 (d) and FIG.7 (a) was formed on the lower clad layer 62. FIG. At that time, as shown in FIG. 7A, the auxiliary portion 76 is also formed together with the core portion 65.

  Next, as shown in FIG. 6 (e), the blade tip surface is a blade whose angle with respect to the surface direction of the blade is 45 °, that is, a blade 68 whose apex angle is 90 ° and whose tip width is 20 μm. (Metal bond blade (grain size 5000)) was used, and the core portion 65 was cut at a rotational speed of 15000 rpm. Specifically, as shown in FIG. 7 (a), the blade 68 is lowered with respect to the core portion 65 arranged at the outermost part while rotating at a moving speed of 0.03 mm / sec. The core part 65 was cut. At that time, the lower clad layer 62 was cut by about 5 μm through the core portion 65. Thereafter, as shown in FIG. 8A, in this state, the blade 68 was moved in the surface direction of the lower cladding layer 62 under the condition of a moving speed of 5 mm / second so as to cut the core portion 65 sequentially. By doing so, as shown in FIGS. 6E and 8B, the core portion 66 having the 45 ° inclined surface 66a was formed. At that time, a 45 ° inclined surface 78 a was also formed in the auxiliary portion 78. Furthermore, the opposing part 67 provided with the inclined surface 67a which opposes the 45 degree inclined surface 66a and inclines on the opposite side to the 45 degree inclined surface 66a was formed. Further, since the core portion is cut using a blade 68 having a tip width of 20 μm, the distance between the inclined surface between the core portion 66 having the 45 ° inclined surface 66a and the facing portion 67 having the inclined surface 67a is as follows. 20 μm. FIG. 7 is a drawing for explaining the start of the inclined surface formation on the core portion. FIG. 8 is a diagram for explaining after the inclined surface is formed on the core portion. 7 and 8 are views as viewed from the upper side perpendicular to the surface direction of the lower cladding layer 62 shown in FIG. 6 (e). FIG. 7B is an enlarged view of a portion surrounded by a broken line 73 in FIG. FIG. 8B is an enlarged view of a portion surrounded by a broken line 77 in FIG.

Next, each of the obtained resin varnishes used in the production of the resin film for the lower cladding layer was diluted 50 times with a mixed solvent in which toluene and MEK were mixed at a mass ratio of 3: 7. A thin brush was applied to the inclined surface. Then, after drying at 100 degreeC for 30 minutes, it exposed by irradiating an ultraviolet light on the conditions of 1 J / cm < ² > with the ultrahigh pressure mercury lamp. Thereafter, heat treatment was further performed at 120 ° C. for 10 minutes. By doing so, each inclined surface was smoothed.

  Next, while observing with a microscope, the transfer film 19 was placed so that the adhesive layer of the transfer film 19 was in contact with the inclined surface 66a of the core portion 66 as shown in FIG. Thereafter, a temperature control type soldering iron 69 covered with a silicone rubber having a thickness of 15 μm on the tip and further provided with a thermocouple was pressed with a force of 2 kg for 5 seconds. At that time, the surface of the silicone rubber was heated to about 170 degrees by a thermocouple. By doing so, the adhesive layer of the transfer film 19 was cured. Thereafter, the polyimide film of the transfer film 19 was peeled off, whereby the metal layer 70 was formed on the inclined surface 66a of the core portion 66 as shown in FIG. This metal layer 70 functions as a micromirror.

  Next, as shown in FIG. 6 (h), an upper clad layer resin film is placed so as to cover the lower clad layer 62 and the core portion 66, and under a pressure condition of 80 ° C. and 0.2 MPa. The upper clad layer resin film was laminated by pressurizing for 120 seconds. Thereafter, the surface of the resin film for the upper clad layer was irradiated with 2000 mJ of ultraviolet light having a wavelength of 365 nm with an ultrahigh pressure mercury lamp. By doing so, as shown in FIG. 6 (h), the upper clad layer resin film was cured, and a second clad layer (upper clad layer) 71 was formed.

  Finally, as shown in FIG. 6I, an optical waveguide was obtained by peeling the substrate 61. The optical path of the guided light that enters and exits the optical waveguide is indicated by an arrow.

(Example 2)
Example 2 will be described with reference to FIG. FIG. 9 is a schematic diagram for explaining the method of manufacturing the optical waveguide according to the second embodiment.

  First, as shown to Fig.9 (a), using the figure flexible double-sided copper clad laminated board (FELIOS (R-F775) by Panasonic Electric Works Co., Ltd.), and patterning one side, it is for mounting. The electric circuit 91a was formed, and the copper foil was etched off on the other side. By doing so, a flexible printed wiring board (flexible board) 91 having an outer size of 130 mm × 130 mm and a thickness of 25 μm was obtained.

  Next, a strong adhesive surface of a re-peeling type double-sided adhesive tape (No. 7692 manufactured by Teraoka Seisakusho Co., Ltd.) is applied to the entire surface of one side of a glass plate having a size of 140 mm × 140 mm × thickness 2 mm. It was laminated under conditions of 80 ° C. and 0.2 MPa using Morton V-130, hereinafter simply referred to as “vacuum laminator V-130”. Further, the surface of the flexible substrate on which each pattern was formed was laminated on the weak adhesive surface of the double-sided adhesive tape under the same conditions using a vacuum laminator V-130. By doing so, the flexible substrate 91 was temporarily bonded to the glass plate 93 as the temporary substrate via the double-sided adhesive tape 92 as shown in FIG.

  An optical waveguide was formed in the same manner as in Example 1 except that a flexible substrate 91 temporarily bonded to a glass plate 93 as shown in FIG. 9B was used instead of the substrate 61. Specifically, it was formed by the steps shown in FIGS. 9C to 9I. In addition, the optical waveguide was formed on the surface of the flexible substrate 91 side instead of the glass plate 93 side of the flexible substrate 91 temporarily bonded to the glass plate 93.

  By doing so, an optical waveguide as shown in FIG. 9I was formed.

  Next, as shown in FIG. 9 (j), a cover lay film (halogen-free cover lay film R-CAES manufactured by Panasonic Electric Works Co., Ltd., 15 μm on one surface of a polyimide film 95 having a thickness of 12.5 μm is formed. A laminated film having a thick adhesive layer 94) was laminated on the upper clad layer 71 using a vacuum laminator V-130 at 120 ° C. and 0.3 MPa. Then, it heated at 160 degreeC for 1 hour. By doing so, the adhesive layer of the coverlay film was cured.

  Finally, the glass plate 93 was peeled off from the flexible substrate 91 together with the double-sided adhesive tape 92. By doing so, an opto-electric composite wiring board having an optical waveguide as shown in FIG. 9K was obtained. The optical path of the guided light that enters and exits the optical waveguide is indicated by an arrow.

(Comparative example)
A comparative example will be described with reference to FIG. FIG. 10 is a schematic diagram for explaining the method of manufacturing the optical waveguide according to the comparative example.

  First, as shown in FIG. 10A, a polycarbonate substrate of 140 mm × 140 mm × thickness 1 mm was prepared as the substrate 201.

  Next, the OPP film is peeled from the lower clad layer resin film, and the lower clad layer resin film is placed on the substrate 201 as shown in FIG. A resin film for the lower clad layer was laminated on the substrate 201 by applying pressure for 120 seconds under a pressure condition. Thereafter, the surface of the resin film for the lower cladding layer was irradiated with 2000 mJ of ultraviolet light having a wavelength of 365 nm with an ultrahigh pressure mercury lamp. By doing so, as shown in FIG. 10B, the lower clad layer resin film was cured, and the first clad layer (lower clad layer) 202 was formed on the substrate 201.

  Next, as shown in FIG.10 (c), the resin film for core parts is mounted on the surface of the lower cladding layer 202, and it pressurizes for 120 second on 60 degreeC and 0.2 MPa pressurization conditions. The core material layer was formed by laminating the core portion resin film on the lower clad layer 202.

  Then, as shown in FIG. 10C, a photomask 204 having a linear pattern of slits is used, and the ultrahigh pressure adjusted so that the irradiation light becomes substantially parallel light on the core material layer through the mask. With a mercury lamp, ultraviolet light having a wavelength of 365 nm was irradiated with a light amount of 2000 mJ. By doing so, the location corresponding to the core portion of the core material layer was cured. As the photomask 204 used here, a photomask capable of forming the core portion 205 shown in FIG. 11 was used. Specifically, 20 slits of a linear pattern having a width of 40 μm and a length of 110 mm were arranged at a pitch of 250 μm.

  Next, a phenomenon treatment was performed using an aqueous cleaning agent (“Clean Through” manufactured by Kao Corporation), which is a freon replacement cleaning liquid. By doing so, the core part 205 was formed on the lower clad layer 202 as shown in FIG.10 (d) and FIG.11 (a).

  Next, as shown in FIG. 10E, the blade tip surface is a blade whose angle with respect to the blade surface direction is 45 °, that is, a blade 206 whose apex angle is 90 ° and whose tip width is 20 μm. (Metal bond blade (particle size: 5000)) was used, and the end of the core part 205 was cut at a rotational speed of 15000 rpm. Specifically, as shown in FIG. 10 (a), the blade 206 is lowered with the moving speed of 0.03 mm / second while rotating the blade 206 with respect to the core part 205 arranged at the outermost part. The core part 205 was cut. At that time, the lower clad layer 202 was cut by about 5 μm through the core portion 205. Thereafter, as shown in FIG. 12A, in this state, the blade 68 was moved in the surface direction of the lower cladding layer 62 under the condition of a moving speed of 5 mm / second so as to cut the core portion 65 sequentially. By doing so, as shown in FIGS. 10 (e) and 12 (b), a core part 205 having a 45 ° inclined surface 205a was formed. In addition, FIG. 11 is drawing for demonstrating the time of the start of inclined surface formation to a core part. FIG. 12 is a diagram for explaining after the inclined surface is formed on the core portion. 11 and 12 are views as seen from above and perpendicular to the surface direction of the lower cladding layer 202 shown in FIG. Moreover, FIG.11 (b) is an enlarged view of the part enclosed with the broken line 210 in Fig.11 (a). FIG.12 (b) is an enlarged view of the part enclosed by the broken line 213 in Fig.12 (a).

Next, each of the obtained resin varnishes used in the production of the resin film for the lower cladding layer was diluted 50 times with a mixed solvent in which toluene and MEK were mixed at a mass ratio of 3: 7. A thin brush was applied to the inclined surface. Then, after drying at 100 degreeC for 30 minutes, it exposed by irradiating an ultraviolet light on the conditions of 1 J / cm < ² > with the ultrahigh pressure mercury lamp. Thereafter, heat treatment was further performed at 120 ° C. for 10 minutes. By doing so, each inclined surface was smoothed.

  Next, while observing with a microscope, the transfer film 19 was placed so that the adhesive layer of the transfer film 19 was in contact with the inclined surface 205a of the core part 205 as shown in FIG. Thereafter, a temperature control type soldering iron 69 covered with a silicone rubber having a thickness of 15 μm on the tip and further provided with a thermocouple was pressed with a force of 2 kg for 5 seconds. At that time, the surface of the silicone rubber was heated to about 170 degrees by a thermocouple. By doing so, the adhesive layer of the transfer film 19 was cured. Thereafter, the polyimide film of the transfer film 19 was peeled to form a metal layer 208 on the inclined surface 205a of the core part 205 as shown in FIG.

  Next, as shown in FIG. 10 (h), a resin film for the upper clad layer is placed so as to cover the lower clad layer 202 and the core part 205, and under pressure conditions of 80 ° C. and 0.2 MPa. The upper clad layer resin film was laminated by pressurizing for 120 seconds. Thereafter, the surface of the resin film for the upper clad layer was irradiated with 2000 mJ of ultraviolet light having a wavelength of 365 nm with an ultrahigh pressure mercury lamp. By doing so, as shown in FIG. 10 (h), the upper clad layer resin film was cured, and a second clad layer (upper clad layer) 209 was formed.

  Finally, as shown in FIG. 10I, the optical waveguide was obtained by peeling off the substrate 61. The optical path of the guided light that enters and exits the optical waveguide is indicated by an arrow.

(Evaluation)
The following evaluation was performed on the formed optical waveguide.

(Waveguide loss measurement)
At one end (incident side end) of the optical waveguide, NAO. The ends of the 21 optical fibers were connected via matching oil (silicone oil). At the other end (output side end), NAO. The ends of the four optical fibers were connected via matching oil. Light from an LED light source with a wavelength of 850 nm was made incident on the optical waveguide through an optical fiber connected to the input side end. Then, the emitted light from the optical waveguide was made incident on the power meter through the optical fiber connected to the output side end, and the light quantity P1 of the emitted light was measured.

  On the other hand, when the optical fiber connected to the input side end and the optical fiber connected to the output side end are directly connected without going through the optical waveguide, the output from the optical fiber connected to the output side end The amount of incident light P0 was measured in the same manner as described above.

  And the insertion loss (waveguide loss) L1 of the optical waveguide with a micromirror was calculated | required by following formula (1).

L1 = -10 log (P1 / P0) (1)
(Mirror loss measurement)
First, the insertion loss L1 was measured in the same manner as the waveguide loss measurement. Thereafter, the micromirror part was cut and the end part was polished, thereby producing an optical waveguide having a length of 100 mm and exposing the end face of the core part of 40 μm × 40 μm at both ends. The insertion loss L2 of the optical waveguide alone (without the micromirror) was measured for the optical waveguide with the core portion exposed at both ends in the same manner as the above-described waveguide loss measurement. The difference between L1 and L2 was taken as the mirror loss. When there were two micromirrors on the input side and the output side, the obtained value was divided by 2 to obtain the mirror loss per micromirror.

  As a result, when the above evaluation was performed on the optical waveguide obtained in Example 1, L1 was 3.2 dB and L2 was 2.2 dB on the average of 20 waveguides. Therefore, the average mirror loss was 0.5 dB.

  Moreover, when the said evaluation was performed about the optical waveguide obtained in Example 2, L1 was 3.8 dB and L2 was 2.2 dB on the average of 20 pieces. Therefore, the average mirror loss was 0.8 dB.

  Moreover, when the said evaluation was performed about the optical waveguide obtained by the comparative example, L1 was 4.8 dB and L2 was 2.4 dB on the average of 20 pieces. Therefore, the average mirror loss was 1.2 dB.

  From these facts, it was found that Example 1 and Example 2 in which the auxiliary part was formed were able to suppress the mirror loss more than the comparative example in which the auxiliary part was not formed. Therefore, it was found that the optical waveguide according to the present invention can form a metal layer with reduced loss in light reflection on the inclined surface.

  As described above, the present specification discloses various modes of technology, of which the main technologies are summarized below.

  An optical waveguide manufacturing method according to an aspect of the present invention includes: an elongated core portion; and an auxiliary portion arranged in parallel with a predetermined interval in the width direction of the core portion on the surface of the first cladding layer. Forming a core part, forming an inclined surface for reflecting light on the core part, and forming a metal layer on the inclined surface by a transfer method. A clad layer forming step of forming a clad layer covering the core portion by forming a second clad layer so as to embed the core portion and the auxiliary portion formed on the first clad layer, The inclined surface forming step is a step of forming the inclined surface in the core portion and processing so that one end surface of the auxiliary portion is adjacent to the inclined surface. It is a manufacturing method.

  According to such a configuration, the metal layer with reduced loss in light reflection can be formed on the inclined surface of the core portion. Therefore, an optical waveguide with reduced loss in light reflection can be obtained. This is because an inclined surface for reflecting light is formed in the core portion, and the metal layer is formed on the inclined surface by attaching a metal layer to the inclined surface of the core portion as described above, for example. It is considered that the metal layer wrapping around the side surface of the core part that can occur at the time can be suppressed by the auxiliary part arranged in parallel with the core part. Accordingly, it is considered that the metal layer can be uniformly pressurized when being attached to the inclined surface. Therefore, it is considered that a metal layer with reduced loss in light reflection can be formed.

  In the method for manufacturing an optical waveguide, the inclined surface forming step is preferably a step in which an end surface of the auxiliary portion forms an inclined surface that is substantially on the same plane as the inclined surface.

  According to such a configuration, it is possible to form a metal layer with a further reduced loss in light reflection on the inclined surface. This is considered to be because the metal layer can be more uniformly pressurized.

  Moreover, in the manufacturing method of the optical waveguide, it is preferable that a distance between the core portion and the auxiliary portion is 10 to 50 μm.

  According to such a configuration, it is possible to form a metal layer with a further reduced loss in light reflection on the inclined surface. This is considered due to the fact that the metal layer can be further prevented from being wrapped around the side surface of the core portion.

  Moreover, in the manufacturing method of the optical waveguide, the inclined surface forming step forms the inclined surface in the core portion, and is opposed to the inclined surface of the core portion and spaced apart from the core portion. It is the process of forming a part, It is preferable that the height of the said opposing part is more than half of the height of the said core part.

  According to such a configuration, it is possible to form a metal layer with a further reduced loss in light reflection on the inclined surface. This is considered to be because the metal layer can be more uniformly pressurized.

  In the optical waveguide manufacturing method, the surface of the facing portion that faces the inclined surface is a surface inclined in a direction opposite to the inclination of the inclined surface, and the core portion and the facing portion The distance is preferably 10 to 100 μm at the nearest place.

  According to such a configuration, it is possible to form a metal layer with a further reduced loss in light reflection on the inclined surface. This is considered to be because the metal layer can be more uniformly pressurized.

  An optical waveguide according to another aspect of the present invention includes a long core portion and a clad layer covering the core portion, and each core portion has an inclined surface for reflecting light. The optical waveguide further includes an auxiliary portion arranged in parallel with a predetermined interval in the width direction of the core portion so that one end surface is adjacent to the inclined surface.

  According to such a configuration, the metal layer with reduced loss in light reflection can be formed on the inclined surface. For example, even when a metal layer is affixed to the inclined surface of the core part, the metal part wraps around the side surface of the core part by an auxiliary part arranged in parallel with the core part. It is thought that it is possible. Accordingly, it is considered that the metal layer can be uniformly pressurized when being attached to the inclined surface. Therefore, it is considered that a metal foil with reduced loss in light reflection can be formed.

  In the optical waveguide, it is preferable that one end surface of the auxiliary portion located adjacent to the inclined surface is substantially on the same surface as the inclined surface.

  According to such a configuration, it is possible to form a metal layer with a further reduced loss in light reflection on the inclined surface. This is considered to be because the metal layer can be more uniformly pressurized.

  The optical waveguide preferably includes a metal layer on the inclined surface.

  The optical waveguide further includes a facing portion facing the inclined surface of the core portion and spaced apart from the core portion, wherein the height of the facing portion is at least half the height of the core portion. It is preferable that

  According to such a configuration, it is possible to form a metal layer with a further reduced loss in light reflection on the inclined surface. This is considered to be because the metal layer can be more uniformly pressurized.

  An opto-electric composite wiring board according to another aspect of the present invention is an opto-electric composite wiring board including the optical waveguide and the electric wiring board.

10, 20, 30 Optical waveguide 11 Core portion 11a Inclined surface 12 First cladding layer (lower cladding layer)
13 Auxiliary part 13a Inclined surface 16 Adhesive layer 17 Metal layer 18 Base material 19 Transfer film (laminated film)
24 Opposite part

Claims (9)

And two or more elongated core portion, and an auxiliary unit for Mazai at a predetermined interval in the width direction of the core portion adjacent the core portion and which forms on the surface of the first cladding layer Process,
An inclined surface forming step for forming an inclined surface for reflecting light on each of the core parts;
A metal layer forming step of forming a metal layer on the inclined surface by a transfer method;
A clad layer forming step of forming a clad layer covering each core part by forming the second clad layer so as to embed each core part and auxiliary part formed on the first clad layer. ,
The inclined surface forming step is a step of forming the inclined surface on each of the core portions and processing the one end surface of the auxiliary portion so as to be adjacent to the inclined surface. A method for manufacturing a waveguide.   The method of manufacturing an optical waveguide according to claim 1, wherein the inclined surface forming step is a step of forming an inclined surface in which one end surface of the auxiliary portion is substantially on the same surface as the inclined surface.   The method for manufacturing an optical waveguide according to claim 1, wherein an interval between the core portion and the auxiliary portion is 10 to 50 μm. The inclined surface forming step, thereby forming the respective core portion and the inclined surface, the opposite to the inclined surface of each of the core portions, be a step of forming a facing portion which is provided apart from the respective core portions ,
The method for manufacturing an optical waveguide according to any one of claims 1 to 3, wherein a height of the facing portion is half or more of a height of the core portion. The surface of the facing portion that faces the inclined surface is a surface that is inclined in a direction opposite to the inclination of the inclined surface,
The method for manufacturing an optical waveguide according to claim 4, wherein a distance between the core portion and the facing portion is 10 to 100 μm at a closest position. Comprising two or more elongated core portions, and a clad layer covering each core portion;
Each core part has an inclined surface for reflecting light,
A metal layer is provided on the inclined surface,
One end face, so that the position adjacent to the inclined surface, the light, characterized by further comprising an auxiliary unit which Mazai at a predetermined interval in the width direction of the core portion adjacent waveguide.   The optical waveguide according to claim 6, wherein one end surface of the auxiliary portion located adjacent to the inclined surface is substantially flush with the inclined surface. The opposite to the inclined surface of each of the core portions, further comprising a facing portion which is provided apart from the each of the core portions,
The optical waveguide according to claim 6 or 7 , wherein a height of the facing portion is half or more of a height of the core portion. An optoelectric composite wiring board comprising the optical waveguide according to any one of claims 6 to 8 and an electric wiring board.

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