JP2005234456A - Manufacturing method of optical circuit substrate and optical circuit substrate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide the manufacturing method of an optical circuit substrate in which an inclined surface constituting an optical deflector is formed on a flat surface and optical loss caused when reflecting light beams on the optical deflector and inputting and outputting the light beams to and from an optical waveguide is made small. <P>SOLUTION: The method is related to manufacturing of the optical circuit substrate which is provided with an optical waveguide 3 formed by a clad 1 and a core 2 and an optical deflector 5 which forms the end face of the core 2 into an inclined surface 4 and performs deflection incidence or deflection emission of light beams. After forming a core resin layer 6 on the clad 1, the core 2 is formed into a waveguide pattern shape by selectively irradiating the core resin layer 6 with light and is developed, and the core resin layer 6 other than the core 2 is eliminated. Then, resin is coated to cover the core 2 to form a coated resin layer 7 having a flat top surface. Then, the coated resin layer 7 is irradiated with a laser beam to eliminate the coated resin layer 7 which covers the core 2 and the top section of the core 2. After that, working is conducted to form the inclined surface 4 of the optical deflector 5 on the portion of the core 2 that is exposed on the eliminated portion. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an optical circuit board in which input / output of an optical signal is performed by an optical deflector that deflects and deflects an optical path provided in a core of an optical waveguide, and a manufacturing method thereof.

  In an optical circuit board formed with an optical waveguide constituting an optical circuit, for example, an opto-electric hybrid board in which an electric circuit and an optical waveguide are mixedly mounted, between the optical waveguide and the electro-optical conversion element mounted on the substrate. In order to propagate light, an optical deflector is provided in the core of the optical waveguide, the light is deflected by the optical deflector, the optical path is refracted, the light is emitted from the optical waveguide, and the light is incident on the optical waveguide. Has been done. This optical deflector can be formed by providing an inclined surface at an angle of 45 ° on the end surface in the longitudinal direction of the core of the optical waveguide and providing a metal reflective film on the inclined surface.

  In order to form such an optical deflector, there are a method of processing an inclined surface in the core of an optical waveguide, a method of forming with a mold, a method of cutting with a blade, and a method of forming with a laser. The method of molding with a mold is to mold the core by mold molding and form an inclined surface at the end of the core at the time of molding, but deformation such as warping of the substrate occurs due to shrinkage after molding However, there is a problem in that there is a possibility that a positional deviation from the optical deflector may occur when an electro-optical conversion element or the like is mounted. The method of cutting with a blade is to form an inclined surface with the blade when forming the core. However, since unnecessary portions are also cut, other cores are cut when the core is narrowed. There is a problem that a malfunction such as the above occurs. On the other hand, the method of forming an inclined surface with a laser has advantages such as being able to process a fine region and flexibly responding to a design change of an optical circuit board. It can be said that it is most suitable for forming a vessel (see, for example, Patent Document 1).

  An example of a method of forming the inclined surface 4 of the optical deflector 5 on the core 2 of the optical waveguide 3 by such laser processing is shown in FIG. First, a clad resin is applied on the substrate 11 and cured by light irradiation or the like to form the clad 1 as shown in FIG. Next, a core resin is applied on the clad 1, and the core resin layer 6 is irradiated with light such as ultraviolet rays through a mask 12 as shown in FIG. The mask 12 has a light passing portion 12a formed in a core forming pattern. The light passing through the light passing portion 12a is irradiated onto the core resin layer 6 so that the core resin layer 6 is partially covered by the pattern. The core 2 can be formed by curing. Then, by removing the uncured core resin layer 6 other than the core 2 by dissolving it in the developer, the core 2 can be patterned as shown in FIG.

Then, a part of the core 2 in the longitudinal direction is irradiated with a laser L so as to cross the width direction of the core, and a part of the core 2 is removed obliquely, whereby the core 2 is formed as shown in FIG. The inclined surface 4 can be formed on the end surface.
JP 2000-117465 A

  Here, as shown in FIG. 5C, the core 2 formed as described above is in a state in which corners on both sides of the upper end portion are chamfered, and the cross-sectional shape of the upper surface tends to be an arcuate convex shape. . When the inclined surface 4 is formed by removing a part of the core 2 obliquely by laser processing, the shape of the core 2 before laser processing is reflected in the laser processing shape. If the cross-sectional shape is an arc-shaped convex shape, the inclined surface 4 formed by laser processing also has a curved surface in the shape of a convex arc having a chamfered corner on both sides as shown in FIG. Easy to be.

  However, when the inclined surface 4 is formed in a convexly curved surface as described above, the light incident on the optical deflector 5 formed by the inclined surface 4 is scattered by reflected light, and the light is deflected by the optical deflector. This causes a problem that a large optical loss occurs when the light is reflected to 5 and input / output to / from the optical waveguide 3.

  The present invention has been made in view of the above points, and the inclined surface constituting the optical deflector can be formed into a flat surface, and the optical when the light is reflected on the reflecting surface and inputted to and outputted from the optical waveguide. It is an object of the present invention to provide an optical circuit board manufacturing method and an optical circuit board that can reduce the loss of the circuit.

  An optical circuit board manufacturing method according to claim 1 of the present invention includes an optical waveguide 3 formed of a clad 1 and a core 2 and forms an end surface of the core 2 on an inclined surface 4 so that light is deflected and incident. Alternatively, in manufacturing an optical circuit board provided with the optical deflector 5 that deflects and emits light, after the core resin layer 6 is formed on the clad 1, the core resin layer 6 is selectively irradiated with light to guide the waveguide. Forming and developing the pattern-shaped core 2 to remove the core resin layer 6 other than the core 2, and then coating the resin so as to cover the core 2 to form a coated resin layer 7 having a flat upper surface, The coating resin layer 7 coated on the core 2 and the upper portion of the core 2 are removed by irradiating a laser from the coating resin layer 7, and the optical deflector 5 is applied to the core 2 at a portion exposed to the removed portion. Characterized by performing the process of forming the inclined surface 4 A.

  According to the present invention, even if the cross-sectional shape of the upper part of the core 2 formed by patterning is an arcuate convex shape, the upper part of the coating resin layer 7 and the core 2 are irradiated by laser irradiation from above the coating resin layer 7. By removing, the flat surface of the coating resin layer 7 is reflected and the upper surface of the core 2 can be formed into a flat surface, and the inclined surface 4 to be processed into the core 2 whose upper surface is a flat surface is high. It can be formed with flatness, and the optical loss when light is reflected on the inclined surface 4 of the optical deflector 5 and input / output to / from the optical waveguide 3 can be reduced.

  According to a second aspect of the present invention, in the first aspect, the resin liquid having a refractive index smaller than that of the core 2 is applied so as to cover the core 2, and then the flat plate 8 is overlaid on the resin liquid. The coating resin layer 7 having a flat upper surface is formed by curing the liquid.

  According to the present invention, the flatness of the upper surface of the coating resin layer 7 can be formed, and when the upper surface of the core 2 is formed on the flat surface by laser irradiation from the upper surface of the coating resin layer 7, the flatness of the upper surface of the coating resin layer 7 is reduced. It can be obtained high.

  An optical circuit board according to the present invention is manufactured by the method according to claim 1 or 2, and the inclined surface 4 processed into the core 2 can be formed with high flatness, and light is deflected. The optical loss can be reduced when the light is reflected by the vessel 5 and input / output to / from the optical waveguide 3.

  According to the present invention, even if the cross-sectional shape of the upper part of the core 2 formed by patterning is an arc-shaped convex shape, the upper part of the coating resin layer 7 and the core 2 are irradiated by laser irradiation from above the coating resin layer 7. By removing, the flat surface of the coating resin layer 7 is reflected, and the upper surface of the core 2 can be formed into a flat surface. Accordingly, the inclined surface 4 to be processed into the core 2 having a flat upper surface can be easily formed on the flat surface. When light is reflected by the optical deflector 5 and input / output to / from the optical waveguide 3. The optical loss can be reduced.

  Hereinafter, the best mode for carrying out the present invention will be described.

  1 and 2 show an example of an embodiment of the present invention. First, a clad 1 is formed on a transparent substrate 11 formed of an electric circuit board or the like as shown in FIG. The clad 1 can be formed by applying a transparent liquid photo-curing resin to the surface of the substrate 11 by spin coating or the like, and irradiating it with light such as ultraviolet rays and curing it. . Next, a core resin layer 6 is formed on the clad 1. As the core resin, a transparent resin having a refractive index higher than that of the resin of the clad 1 is used. By applying a liquid photocurable resin to the surface of the clad 1 by spin coating or the like, the core resin layer 6 is used. Can be formed.

  Then, as shown in FIG. 2B, a mask 12 is disposed on the core resin layer 6, and light such as ultraviolet rays is irradiated through the mask 12. The mask 12 has a light passage portion 12a formed in a pattern shape for forming a core, and light that has passed through only the light passage portion 12a is irradiated to the core resin layer 6 in a pattern shape. The core resin layer 6 is partially cured in a pattern shape, and the pattern-shaped core 2 can be formed in the core resin layer 6. Then, by removing the uncured core resin layer 6 other than the core 2 by dissolving it in the developer, the core 2 protruding above the clad 1 can be formed as shown in FIG. As shown in FIG. 2C, the core 2 formed in this way is in a state in which corners on both sides of the upper end portion are chamfered, and the cross-sectional shape of the upper surface tends to be an arcuate convex shape.

  After forming the core 2 protruding above the clad 1 in this way, a coating resin layer 7 is formed so as to cover the core 2 as shown in FIG. As the resin of the coating resin layer 7, a transparent resin having a refractive index lower than that of the resin of the core 2 is used, and a coating resin is applied by applying a liquid photocurable resin and curing it by irradiating light such as ultraviolet rays. Layer 7 can be formed. Here, the upper surface of the coating resin layer 7 is formed to be a flat surface, and the upper surface of the coating resin layer 7 is made as flat as possible by using a low-viscosity resin having good fluidity. Is preferred. Therefore, the viscosity of the resin of the coating resin layer 7 is desirably in the range of 100 to 3000 cps. Further, it is desirable to select the resin of the coating resin layer 7 so that the etching rates of the coating resin layer 7 and the core 2 by laser irradiation are as equal as possible.

  Next, after the coating resin layer 7 is sufficiently cured, a laser is irradiated from above the coating resin layer 7 at a location where the optical deflector 5 is formed on the core 2. The laser irradiation is performed in a range including the entire length of the core 2 in the width direction and the coating resin layers 7 on both sides thereof in a part of the pattern-shaped core 2 in the longitudinal direction. Then, by irradiating the laser L with a uniform output in this range, the coating resin layer 7 covering the core 2 and the upper part of the core 2 are removed as shown in FIGS. 2 (e) and 1 (a). In addition, the coating resin layer 7 on both sides of the core 2 can be removed, and the recess 13 is formed in the removed portion. As shown in FIG. 2E, the core 2 and the coating resin layer 7 are exposed flush with each other at the bottom surface of the recess 13, and the upper surface of the coating resin layer 7 is formed as a flat surface as described above. Therefore, the upper surface of the core 2 exposed in the recess 13 formed by laser irradiation can also be formed in a flat surface reflecting the flat surface. The depth at which the upper portion of the core 2 is removed is set so that the cross-sectional shape is deeper than the arcuate convex portion.

  After flattening the upper surface of the core 2 where the optical deflector 5 is to be formed as described above, the inclined surface 4 is formed on the core 2 at this location as shown in FIG. The process of forming the inclined surface 4 can be performed by irradiating the core 2 with a laser, but can also be performed by chemical etching. Here, since the upper surface of the core 2 is formed as a flat surface as described above, the inclined surface 4 can be formed with good flatness.

FIG. 3 shows an example of a method of forming the inclined surface 4 by laser irradiation, and processing of the inclined surface 4 is performed while confirming the state of the processed surface using the half mirror 16, the total reflection mirror 17, and the interferometer 18. Can be done. That is, the processing laser L is output toward the half mirror 16, the laser L is reflected by the half mirror 16, and the reflected laser L ₁ is irradiated onto the core 2 to process the inclined surface 4 on the core 2. A part of the laser L is transmitted through the half mirror 16, the transmitted laser L ₂ is reflected by the total reflection mirror 17, and the reflected light L ₃ is further reflected by the half mirror 16 and enters the interferometer 18. . On the other hand, a part of the laser L ₁ that irradiates the core 2 and processes the inclined surface 4 is reflected by the processing surface, and the reflected light L ₄ passes through the half mirror 16 and enters the interferometer 18. The interference fringes generated by the interference between the reflected light L ₃ reflected by the total reflection mirror 17 and the reflected light L ₄ reflected by the processing surface in this way are observed by the interferometer 18, thereby The shape of the processed surface can be grasped. Therefore, the inclined surface 4 can be processed while checking the state of the processed surface in this way, and the inclined surface 4 can be controlled by controlling the output of the processing laser L in accordance with the state of the processed surface. Can be processed with higher flatness.

  Then, by depositing a metal on the inclined surface 4 formed as described above and providing the reflective film 14 having a thickness of 100 nm or more as shown in FIG. 1C, the optical deflector 5 having high reflection efficiency can be formed. It can be done. When the refractive index of the resin of the coating resin layer 7 is lower than that of the core 2 or the same material as that of the cladding 1, the optical waveguide 3 can be constituted by the cladding 1, the core 2 and the coating resin layer 7. If the coating resin layer 7 cannot be used as a cladding, the coating resin layer 7 is removed with chemicals or the like so as not to impair the shape of the core 2, and a cladding is provided again. The optical waveguide 3 can be constituted by a newly formed clad. In the optical circuit board thus formed, the light propagating through the core 2 of the optical waveguide 3 is reflected by the inclined surface 4 of the optical deflector 5 to bend and deflect the optical path, and is emitted through the substrate 11. In addition, the light incident through the substrate 11 is reflected by the inclined surface 4 of the optical deflector 5, and the optical path is bent and deflected so that the light can propagate through the optical waveguide 3. . At this time, since the inclined surface 4 forming the optical deflector 5 is formed with high flatness as described above, when the light is reflected on the inclined surface 4 of the optical deflector 5 and is input to and output from the optical waveguide 3. Optical loss can be reduced.

  FIG. 4 shows another example of the embodiment of the present invention. In this embodiment, after forming the core 2 protruding above the clad 1 as shown in FIG. 2C, a liquid resin is applied so as to cover the core 2 to form the coating resin layer 7. In order to form the coating resin layer 7, the flat plate 8 having a flat bottom surface is overlapped and adhered onto the liquid resin, and the upper surface is cured to a flat surface by the flat plate 8. It is a thing. A transparent glass plate or the like can be used as the flat plate 8. By irradiating light such as ultraviolet rays through the flat plate 8, the photocurable resin is cured and the covering resin layer 7 is formed. It can be formed. Even if the liquid resin has a low viscosity, if it is difficult to obtain the flatness of the upper surface only by coating, the upper surface is molded with the flat plate 8 in this way, and the flatness of the upper surface is increased. The resin layer 7 can be formed, and when the upper surface of the core 2 is formed to be a flat surface by irradiating the laser from above the coating resin layer 7 as described above, a high flatness can be obtained. It is.

An example of embodiment of this invention is shown, (a)-(c) is a schematic side sectional drawing, respectively. An example of embodiment same as the above is shown, and (a) to (e) are schematic front sectional views, respectively. It is a schematic side sectional view showing an example of the above embodiment. It is a general | schematic front sectional drawing which shows an example of other embodiment same as the above. A prior art example is shown, (a)-(c) is a schematic front sectional view. It shows a conventional example same as above, (a) is a schematic side cross-sectional view, (b) is a cross-sectional view taken along the line II in (a).

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Cladding 2 Core 3 Optical waveguide 4 Inclined surface 5 Optical deflector 6 Core resin layer 7 Coating resin layer 8 Planar plate

Claims (3)

  In manufacturing an optical circuit board having an optical waveguide having an optical waveguide formed of a clad and a core, and having an end surface of the core formed on an inclined surface and deflecting light incident on or deflected from the core, After the core resin layer is formed, the core resin layer is selectively irradiated with light to form a waveguide pattern-shaped core and developed to remove the core resin layer other than the core, and then the core Cover the resin to form a coating resin layer with a flat top surface, and irradiate the laser from above the coating resin layer to remove the coating resin layer coated on the core and the upper part of the core. A method of manufacturing an optical circuit board, comprising performing processing for forming an inclined surface of an optical deflector on a core at a portion exposed at a removed portion.   A resin resin with a refractive index lower than that of the core is applied so as to cover the core, and then the resin liquid is cured with a flat plate overlaid on the resin liquid to form a coating resin layer with a flat upper surface. The method of manufacturing an optical circuit board according to claim 1. An optical circuit board manufactured by the method according to claim 1.

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