JP2009145867A - Optical waveguide, optical waveguide module, and optical element mounting substrate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical waveguide having a new mirror structure that has no fouling of a mirror surface, has a low reflection loss, and hardly becomes a damage base when deformed. <P>SOLUTION: The optical waveguide comprises a core layer including a core part determining an optical path direction, and a clad part lower in refractive index than the core part; and clad layers laminated on both faces of the core layer. A hollow mirror structure defining the mirror surface for changing the optical path of light incident to the optical waveguide and light emitted from the optical waveguide is provided in a predetermined position along the optical path direction of the core part. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an optical waveguide, an optical waveguide module, and an optical element mounting substrate.

  In recent years, there has been an increasing demand for electronic devices with smaller size and higher performance. In particular, in order to cope with signal speeding up, speeding up of signal transmission paths in electronic devices by connecting electronic components with optical signals is being studied. In order to make a connection using an optical signal, an optical / electric hybrid board having optical wiring and electrical wiring is used. The optical wiring has an optical waveguide composed of a core portion and a cladding portion, and an optical signal is transmitted by transmitting light through the core portion of the optical waveguide.

  In an electronic device provided with an optical / electrical hybrid board, a plurality of electronic components are mounted on the board. An input / output electric signal of an electronic component is converted into an optical signal by an optical element, and the optical signal is propagated to an optical waveguide. Next, the propagated optical signal is returned to an electrical signal by another optical element, and the electrical signal is connected to another electronic component. Conventionally, in an optical / electrical hybrid substrate, an optical waveguide is formed in a rigid substrate, and the optical waveguide is integrated with the rigid substrate. For example, an optical element and an electronic component are mounted on a rigid substrate, and an electrical signal is transmitted through electrical wiring formed on the opposite side of the mounting surface through the substrate, and the optical signal is It propagates from the optical waveguide formed in the substrate, penetrates the insulating layer from the optical waveguide, and is transmitted to the light receiving and emitting part of the optical element (for example, see Patent Document 1). In such an optical / electrical hybrid substrate, since the optical element is mounted on the substrate, a mirror surface for bending light propagating through the optical waveguide in a direction perpendicular to the substrate is provided in the optical waveguide (for example, Patent Literatures 1 to 3).

JP 2002-182049 A Japanese Patent Laid-Open No. 10-300961 JP 2006-98798 A

  However, since the mirror surface provided in the conventional optical waveguide is formed from above the cladding layer by dicing, hot embossing, laser processing, etc., a part of the cladding layer is completely lost and the mirror of the core portion The surface is exposed to the ambient atmosphere. Since the mirror surface exposed to the ambient atmosphere is easily damaged by dust or dust, it is necessary to bury the opening with a resin or an insulating layer. However, when the mirror surface of the core portion is in contact with the resin or the insulating layer, the difference in refractive index from the core portion on the mirror surface is smaller than when the mirror surface is in contact with air, and as a result, the reflection efficiency is lowered. In addition, the conventional structure for defining the mirror surface has a shape in which a notch is provided in the optical waveguide, and therefore there is a problem that when the optical waveguide is deformed, the mirror structure is easily damaged. In fact, in optical waveguides in which multiple cores are arranged at narrow intervals at narrow intervals, the “notch” effect becomes prominent when the mirror structure is juxtaposed, and the optical waveguide is easily broken at the mirror structure. It may end up.

  Therefore, the present invention provides an optical waveguide having a novel mirror structure that is not damaged by dust or dust adhesion, that is, reflection loss due to the mirror surface is suppressed as much as possible, and that it is less likely to become a damaged base during deformation. The purpose is to provide. In addition, the present invention provides a new mirror structure combined with a crossed waveguide in which a plurality of cores intersect, and a multilayered structure of such a crossed waveguide, and the density and flexibility of optical wiring. Another object of the present invention is to easily provide a compact optical waveguide sheet having a high height. It is another object of the present invention to provide an optical waveguide module and an optical element mounting substrate having such an optical waveguide.

  The above object is achieved by the present invention comprising the following (1) to (10).

  (1) An optical waveguide formed by surrounding a core portion that defines an optical path direction with a clad layer having a refractive index lower than that of the core portion, and at a predetermined position along the optical path direction of the core portion. An optical waveguide comprising a hollow mirror structure that defines a mirror surface for converting an optical path of incident light or light emitted from the optical waveguide.

  (2) The optical waveguide according to (1), wherein the height of the hollow mirror structure is equal to or greater than the thickness of the core portion.

  (3) The above (1) or (2), wherein an additional hollow mirror structure is provided at a position different from the predetermined position in the same optical path including the predetermined position where the hollow mirror structure is provided An optical waveguide according to 1.

  (4) The optical waveguide according to any one of (1) to (3), wherein the mirror surface of the hollow mirror structure is at an angle of 40 to 50 ° with respect to the optical path direction.

  (5) The optical waveguide according to any one of (1) to (4), wherein the optical path direction is converted by the mirror surface into a substantially normal direction with respect to a plane defined by the optical waveguide. .

  (6) The optical waveguide is an optical waveguide in which a plurality of core portions are arranged at a narrow interval at a narrow interval, and the hollow mirror structures are juxtaposed independently for each core portion, The optical waveguide according to any one of 1) to (5).

  (7) A common hollow mirror structure in which the optical waveguide is an optical waveguide in which a plurality of core portions are arranged at narrow intervals at a narrow interval, and the hollow mirror structure extends over two or more of the core portions. The optical waveguide according to any one of (1) to (5), wherein:

  (8) Any of the above (1) to (5), wherein the optical waveguide is a branched optical waveguide having a core portion branched, and a hollow mirror structure is installed at an arbitrary position of each branched core portion. The optical waveguide according to claim 1.

  (9) The optical waveguide according to any one of (1) to (4), wherein the optical path direction is converted by the mirror surface within a plane defined by the optical waveguide.

  (10) The above (9), wherein the optical waveguide is an intersecting waveguide where a plurality of core portions intersect, and the hollow mirror structure is disposed in at least one of the intersecting regions of the core portions. ).

  (11) The optical waveguide according to (10), wherein the hollow mirror structure is installed so as to branch one optical path in two directions in the intersecting region.

  (12) The optical waveguide according to (10), wherein the hollow mirror structure is installed so as to branch one optical path in three directions in the intersecting region.

  (13) The intersecting waveguide is a multi-layered intersecting waveguide in which the core portion overlaps two or more above and below via a clad, and is disposed so as to optically connect the upper and lower core portions. The optical waveguide according to any one of (10) to (12), wherein the hollow mirror structure is installed at a predetermined position.

  (14) Any of the above (10) to (13), wherein the intersecting waveguide has an anti-interference clad structure in which a low refraction region having a refractive index lower than that of the core portion is provided on an outer peripheral portion of the intersecting region. The optical waveguide according to item 1.

  (15) The optical waveguide includes a core layer including a core portion that defines an optical path direction, a cladding portion having a lower refractive index than the core portion, and a cladding layer laminated on both surfaces of the core layer. The optical waveguide according to any one of to (14).

  (16) The optical waveguide according to (15), wherein the core layer and the cladding layer are made of a polymer material.

  (17) The optical waveguide according to (16), wherein the polymer material includes a main chain mainly composed of addition polymerization type norbornene.

  (18) An optical waveguide module comprising the optical waveguide according to any one of (1) to (8) and (15) to (17), a light emitting element and / or a light receiving element, wherein the hollow mirror The light emitted from the light emitting element by the structure and the light emitting element and / or the light receiving element enters the optical waveguide through the mirror surface of the hollow mirror structure and / or the light emitted from the optical waveguide An optical waveguide module characterized by being aligned so as to enter the light receiving element through a mirror surface of the hollow mirror structure.

  (19) An optical element mounting board including the optical waveguide module according to (18) and an electric circuit board.

  (20) The light according to (19), wherein the optical waveguide module has a receptor structure for providing electrical continuity between an electrode of the light emitting element and / or a light receiving element and an electrode of the electric circuit board. Element mounting board.

  According to the present invention, by providing the hollow mirror structure that defines the mirror surface in the core portion of the optical waveguide, the mirror surface is not exposed to the surrounding atmosphere, and the mirror surface is not contaminated by dust or dust adhesion. It will be resolved. Further, since the mirror surface is in contact with air, a sufficient difference in refractive index from the core portion is ensured, and reflection loss at the mirror surface is extremely small. Further, since the mirror structure is a hollow mirror structure, a “notch” shape is not given to the optical waveguide, and the mechanical strength of the optical waveguide is improved. This improvement in mechanical strength is particularly noticeable in the case of an optical waveguide in which a plurality of core portions are arranged at narrow intervals at narrow intervals and mirror structures are juxtaposed. Further, according to the present invention, by combining the novel mirror structure with the crossed waveguide or the multilayered crossed waveguide, the density and the degree of freedom of the optical wiring are higher than those of the conventional optical waveguide sheet in which the optical fiber is curvedly laid. A high and compact optical waveguide sheet can be provided more easily.

  Hereinafter, an optical waveguide, an optical waveguide module, and an optical element mounting substrate according to the present invention will be described in detail with reference to suitable embodiments shown in the accompanying drawings as appropriate.

  FIG. 1 shows a basic configuration of an optical waveguide according to the present invention. FIG. 1A is a partial perspective view showing an optical waveguide 1 in which a core portion 2 that defines an optical path direction is surrounded by a cladding layer (an upper cladding layer 3 and a lower cladding layer 4) having a refractive index lower than that of the core portion. It is. The optical waveguide 1 shown in FIG. 1A is formed on the entire surface of the lower cladding layer 4 having the core portion 2 arranged in a predetermined pattern, for example, as described in JP-A 2000-199827. It can be manufactured by forming the upper cladding layer 3 by a coating method. As another aspect of the basic structure of the optical waveguide according to the present invention, FIG. 1B shows a core layer including a core portion 2 that defines an optical path direction and a cladding portion 3 ′ having a lower refractive index than the core portion, and the core layer. FIG. 2 shows a partial perspective view of an optical waveguide 1 including clad layers (upper clad layer 3 and lower clad layer 4) laminated on both sides of the optical waveguide 1; Hereinafter, the best mode for carrying out the present invention in the optical waveguide of the type shown in FIG. 1B will be described in detail. However, the implementation of the present invention is limited to such an optical waveguide. is not.

  FIG. 2 is a schematic diagram showing an example of a conventional structure that defines a mirror surface in an optical waveguide. FIG. 2 shows a cross section of the optical waveguide 10 cut along the core portion 12 that defines the optical path direction, for example, as cut along the line B-B ′ in FIG. The optical waveguide 10 includes a mirror structure 14 that defines a mirror surface that forms an angle of about 45 ° with respect to the optical path direction. By this mirror surface, light that passes through the upper cladding layer 11 from the outside of the optical waveguide 10 and enters the core portion 12 of the optical waveguide 10, or is transmitted through the upper cladding layer 11 from the core portion 12 of the optical waveguide 10 The optical path LP of the light emitted out of the plane of the waveguide 10 is converted into a substantially normal direction with respect to the plane defined by the optical waveguide 10. The mirror structure 14 shown in FIG. 2 is formed by completely deleting a part of the lower cladding layer 13 (through the vertical direction). As another example of the conventional structure, there is a mirror structure formed by partially or completely deleting a part of the upper cladding layer 11 (not shown). As shown in FIG. 2, when a part of the cladding layer is completely lost and the mirror surface of the core portion 12 remains exposed to the surrounding atmosphere, the mirror surface is easily damaged by dust or dust adhesion. Therefore, in general, the mirror structure 14 is a solid structure embedded with a resin or an insulating layer. However, when the mirror surface is in contact with the resin or the insulating layer, the difference in refractive index from the core portion on the mirror surface is smaller than when the mirror surface is in contact with air (refractive index = 1), and as a result, the reflection efficiency is lowered. In addition, a structure in which a part of the cladding layer is completely deleted has a shape with a notch in the optical waveguide. Therefore, when the optical waveguide is deformed, stress is concentrated on the mirror structure and the optical waveguide is damaged. It becomes easy.

  FIG. 3 is a schematic diagram showing an example of a hollow mirror structure according to the present invention that defines a mirror surface in an optical waveguide. FIG. 3 shows a cross section of the optical waveguide 20 cut along the core portion 22 that defines the optical path direction, as in FIG. The optical waveguide 20 includes a hollow mirror structure 24 that defines a mirror surface that forms an angle of preferably 40-50 °, more preferably about 45 ° with respect to the optical path direction. By this mirror surface, light that passes through the upper clad layer 21 from the outside of the optical waveguide 20 and enters the core portion 22 of the optical waveguide 20, or is transmitted through the upper clad layer 21 from the core portion 22 of the optical waveguide 20. The optical path LP of the light emitted out of the plane of the waveguide 20 is converted in a substantially normal direction with respect to the plane defined by the optical waveguide 20. The shape of the hollow mirror structure according to the present invention is not limited as long as the optical path direction is converted into a substantially normal direction so as to penetrate the upper cladding layer. For example, in the hollow mirror structure according to the present invention, the cross section along the core portion may be an isosceles triangle as shown in FIG. The height of the hollow mirror structure generally only needs to be in the range of 30 to 80 μm, and is substantially the same as the thickness of the core layer including the core portion 22 as shown in FIG. It may be larger than the thickness. In the case where the height of the hollow mirror structure according to the present invention is larger than the thickness of the core layer, the hollow mirror structure 34 is composed of the upper clad layer 31, the core portion 32, and the lower clad layer 33 as shown in FIG. 4B, an embodiment in which the hollow mirror structure 44 extends over two layers of the upper clad layer 41 and the core portion 42, and a hollow shape as shown in FIG. 4C. An embodiment in which the mirror structure 54 extends over two layers of the core portion 52 and the lower cladding layer 53 is included, and both embodiments are included in the present invention.

  As shown in FIGS. 3 and 4, the hollow mirror structures 24, 34, 44, 54 according to the present invention are completely sealed with the cladding layers 21, 23, 31, 33, 41, 43, 51, 53. Therefore, the mirror surfaces of the core portions 22, 32, 42, and 52 are not soiled by dust or dust adhering from the surrounding atmosphere. Moreover, since the inside of the hollow mirror structures 24, 34, 44, 54 according to the present invention is filled with air (refractive index = 1), the difference in refractive index from the core portions 22, 32, 42, 52 on the mirror surface. Becomes sufficiently large, and reflection loss is suppressed. Furthermore, since the hollow mirror structures 24, 34, 44, 54 according to the present invention do not give the optical waveguide a “notch” shape, the mechanical strength of the optical waveguide is significantly improved.

  In the actual optical waveguide, as shown in FIG. 5 (A), a plurality of core portions 62 are arranged in a plurality of intervals at narrow intervals, and the hollow mirror structures 64 are juxtaposed independently for each core portion. There is a case. Even in such a case, since the hollow mirror structure according to the present invention does not exhibit the “notch” effect, the optical waveguide is not easily broken at the portion of the hollow mirror structure. Further, as shown in FIG. 5B, a common hollow mirror structure 74 that spans two or more core portions 72 may be formed. The formation of such a common hollow mirror structure 74 has an advantage in the manufacturing process because a plurality of mirror surfaces can be formed at one time, particularly when dicing or hot embossing is employed.

  As shown in FIG. 6, the optical waveguide according to the present invention may be a branched optical waveguide in which the core portion 82 is branched. In this case, the hollow mirror structure 84 can be provided at an arbitrary position of each branched core portion. The branching type optical waveguide itself is known, and in the present invention, for example, the optical demultiplexing type described in Japanese Patent Application Laid-Open Nos. 2004-279937 and 2006-293171, and Japanese Patent Application Laid-Open No. 2006-330436. The described optical multiplexing types and combinations thereof can be used. For the method of manufacturing the branched optical waveguide, refer to each of the above publications.

  In the optical waveguide according to the present invention, light is incident on the core portion of the optical waveguide through the upper cladding layer from the outside of the optical waveguide by providing one hollow mirror structure at two different positions in the same optical path. Is bent in a substantially vertical direction by one hollow mirror structure to propagate the core part, and the light after propagation is bent in a substantially vertical direction by the other hollow mirror structure and is transmitted through the upper cladding layer from the core part of the optical waveguide. Thus, it can be applied as a surface emitting laser (VCSEL) that emits light out of the plane of the optical waveguide. By using the optical waveguide according to the present invention, the electronic components can be connected by an optical signal, and thus the speed of the signal transmission path in the electronic device can be realized.

  The present invention can also be applied to an optical waveguide in which the optical path LP is converted in the plane defined by the optical waveguide 90 as shown in FIG. In order to bend the optical path within a plane defined by the optical waveguide, the above-described branched optical waveguide having a bent core portion may be used. However, since there is a certain limit (lower limit value) on the radius of curvature of the core portion, further miniaturization of the optical waveguide device can be achieved by using a mirror structure. Although FIG. 7 shows a mode in which the optical path LP is converted in a substantially right angle direction, the conversion angle of the optical path LP is not limited, and it can be easily understood that the optical path LP can be arbitrarily set within a range of 0 to 180 degrees. Like.

  Furthermore, the present invention can also be applied to a crossed waveguide 90 in which a plurality of core portions 92 intersect as shown in FIG. In the crossed waveguide 90 shown in FIG. 8, the core portions 92 are arranged in a grid pattern. However, the cross structure of the core portion 92 is not limited to the orthogonal shape as shown in FIG. In particular, by making the crossing angle of the core portion 92 larger or smaller than 90 ° (orthogonal), the light interference ratio can be arbitrarily changed. By appropriately installing a hollow mirror structure 94 in at least one of the intersecting regions of the core portion 92 of the intersecting waveguide 90, one or two or more optical paths LP can be converted into arbitrary directions, respectively. Conversion type) optical waveguides can be provided. Thus, the ubiquitous optical waveguide combining the crossed waveguide and the hollow mirror structure according to the present invention has an optical wiring compared to a conventional optical waveguide sheet in which a core portion or optical fiber with a limited radius of curvature is laid. A compact optical waveguide sheet having a high density and a high degree of freedom can be provided more easily.

  In the intersecting region of the core portion 92 of the intersecting waveguide 90, as shown in FIG. 9A, the hollow mirror structure 94 can be installed so as to convert one optical path LP only in one direction. . Further, as shown in FIG. 9B, by installing the hollow mirror structure 94 so that a part of the light propagating through one optical path is reflected, one optical path LP is changed in a straight traveling direction. It is also possible to branch in two directions. Further, as shown in FIG. 9C, a hollow mirror structure 94 that reflects a part of the light propagating along one optical path in one direction and an additional hollow that reflects the remaining light in another direction. By installing the mirror structure 94, one optical path LP can be branched in two directions not including the straight traveling direction. As a combination of the mode shown in FIG. 9B and the mode shown in FIG. 9C, as shown in FIG. 9D, a part of the light propagating through one optical path is unidirectionally. By installing a reflecting hollow mirror structure 94 and an additional hollow mirror structure 94 that reflects a part of the remaining light in another direction, one optical path LP is branched in three directions including a straight traveling direction. You can also

  It is also possible to make the optical path three-dimensional by superimposing a plurality of intersecting waveguides vertically. An example of such a multilayered crossed waveguide is schematically shown in FIG. FIG. 10A is a partial perspective view showing a multi-layered (two-layered) crossed waveguide in which a core portion 92 is vertically overlapped with an interlayer clad 95 interposed therebetween. The illustrated two-layered crossed waveguide includes two core layers including a core portion 92 that defines an optical path direction and a cladding portion 96 having a refractive index lower than that of the core portion. Between the core layers, an interlayer clad 95 having a thickness sufficient to prevent vertical interference of the core portion 92 is disposed. Specifically, the thickness of the interlayer cladding 95 should be set to at least 1 μm, preferably 2 μm or more. An upper cladding layer 93 and a lower cladding layer 97 are disposed on the uppermost and lowermost portions of the core layer, respectively. Each core layer constitutes a crossed waveguide as shown in FIG. That is, in each core layer, a hollow mirror structure is appropriately installed in at least one of the intersecting regions of the core portion 92, so that one or more optical paths LP are converted into an arbitrary direction in a plane. . In order to make the optical path LP three-dimensional, a hollow mirror structure as shown in FIG. 3 can be installed at a predetermined position so as to optically connect the upper and lower core portions. FIG. 10B shows an example of two hollow mirror structures 94 installed so as to optically connect the upper and lower core portions 92. In this case, the light converted in the normal direction by one hollow mirror structure 94 passes through the interlayer cladding 95. Light that has penetrated into another core part 92 at the upper part or the lower part can be further converted into the normal direction by another hollow mirror structure 94 and propagated through the core part 92. In order to reduce optical loss when penetrating the interlayer cladding 95, the thickness of the interlayer cladding 95 is desired to be 10 μm or less, preferably 5 μm or less. The multilayered crossed waveguide shown in the figure has two core layers, but the number of core layers is not limited, and can be freely designed according to the application. By combining the multilayered ubiquitous optical waveguide and the hollow mirror structure according to the present invention, it is possible to provide an optical waveguide sheet with higher density and flexibility of optical wiring.

  In the crossed waveguides as shown in FIGS. 8 to 10, a part of the light propagating along a certain optical path has a problem of interference that enters another crossing optical path in the crossing region, or another crossing type waveguide. There is a problem of light loss transmitted through the side surface of the optical path and scattered. As a method for reducing or eliminating such a problem, it is known to employ an interference preventing clad structure in which a low refractive region having a refractive index lower than that of a core portion is provided on the outer periphery of the intersecting region of the intersecting waveguide. An example of a crossed waveguide having such a crosstalk prevention clad structure is shown in FIG. As shown in FIG. 11, an interference preventing cladding structure in which a low refractive index region having a refractive index lower than that of the core portion is provided on the outer peripheral portion of the intersecting region is formed by cutting the core portion 92 before and after the intersecting region 92 ′. In this case, the refractive index of the low refractive region is equal to that of the surrounding cladding. The interval at which the core portion 92 is cut (the width of the low refractive region) is preferably as small as possible in order to reduce optical loss. For example, it is desirable that the interval be 10 μm or less, preferably 5 μm or less. On the other hand, in order to reflect light on the side surface of the intersection region 92 ′, it is necessary that the low refraction region has a certain width, so depending on the difference in refractive index between the intersection region 92 ′ and the low refraction region, The width of the low refractive region should be set to at least 1 μm, preferably 2 μm or more. Further, if the width of the low refractive region is constant, the interference is reduced as the width of the core portion is narrowed. By providing such an anti-interference clad structure, light that is repeatedly reflected on the side surface of the core portion 92 and propagates through the optical path LP can be similarly reflected on the side surface of the intersecting region 92 '. In the crossed waveguide 90 shown in FIG. 11, the crossing structure of the core part 92 is orthogonal. However, the crossing angle of the core part 92 is larger than 90 ° (orthogonal) by providing an interference preventing cladding structure. Or even if it is made smaller, the interference ratio does not change.

  It is convenient to form the interference preventing clad structure using an appropriate photomask when manufacturing the optical waveguide. For example, when a core layer is formed by a post-irradiation method to be described later, a photomask having mask closing portions 91 and 91 ′ as shown in FIG. By forming the clad portion, an interference preventing clad structure can be formed simultaneously with the core layer. As shown in FIG. 12B, when ultraviolet light is irradiated through such a photomask, the lower part of the mask closing portions 91 and 91 ′ becomes the core portions 92 and 92 ′, and the region receiving the ultraviolet light is It becomes the clad part 96 (low refractive area).

  In addition to the patterning method as described above, the anti-interference clad structure is formed by cutting an excimer laser or the like before and after the crossing region of the core portion, and forming a refractive index modulation liquid such as glycerin (refractive index 1.46) in the excised portion. , Can also be formed by a method of filling. The refractive index of the low refractive region needs to be lower than the refractive index of the core portion, and is particularly preferably equal to the refractive index of the cladding portion. On the other hand, if the refractive index of the low refractive region is too low, Fresnel reflection (reflection due to a difference in refractive index) occurs, which is not preferable. Further, as a refractive index modulation method, a thermo-optic effect (TO effect), which is a phenomenon in which the refractive index changes with temperature, or an electro-optic effect (EO effect), which is a phenomenon in which the refractive index changes when a voltage is applied, is used. You can also

  The hollow mirror structure defining the mirror surface according to the present invention can be manufactured by deleting a part of the core portion of the optical waveguide. For deletion of a part of the core part, for example, a laser processing method as described in JP-A-8-318386, for example, a dicing method as described in Patent Document 2, for example, Patent Document 3 The embossing method etc. which are described can be employ | adopted.

Briefly describing the method of forming a hollow mirror structure using a laser processing method, by irradiating a laser to a part of the core portion of the optical waveguide, and by changing the irradiation region of the laser relative to the core portion, By changing the laser irradiation time to the part that forms the hollow mirror structure of the core part, and adjusting the reach of the laser core in the depth direction, the core material is removed and hollowed A mirror structure can be formed. Thus, since a mirror surface can be formed by laser irradiation, a hollow mirror structure can be easily formed in an arbitrary pattern at an arbitrary position. Examples of the laser include an excimer laser such as ArF and KrF, a YAG laser, and a CO ₂ laser. Irradiation energy of the laser is dependent on the constituent material of the core portion is preferably in the range of 100~1000mJ / cm ^2, in particular in the range of 250~700mJ / cm ² is preferred. When the irradiation energy is within the above range, the constituent material of the core portion can be removed in a short time. Although the irradiation frequency of a laser depends on the constituent material of a core part, the range of 50-300 Hz is preferable and the range of 50-200 Hz is especially preferable. When the frequency is within the above range, the smoothness of the inclined surface (mirror surface) is particularly excellent. Moreover, although the size which irradiates a laser to a core part is dependent on the magnitude | size of the hollow mirror structure to form, it is preferable that it is 80-200 micrometers x 80-200 micrometers, and it is 100-150 micrometers x 100-150 micrometers especially Is preferred. Thereby, a fine hollow mirror structure can be formed.

  In the case of a hollow mirror structure for converting the optical path LP in the plane defined by the optical waveguide 90 as shown in FIG. 7 or FIG. 8, a laser is irradiated to a part of the core portion of the optical waveguide, By changing the irradiation region of the laser with respect to the core part relatively, the constituent material of the core part can be removed to form the hollow mirror structure. In this case, it is not necessary to change the reach of the laser core in the depth direction. FIG. 13 shows an example of a method of forming the hollow mirror structure 94 in the intersecting region of the core portion 92 in the intersecting waveguide 90 as shown in FIG. As shown in FIG. 13A, a laser irradiation unit 98 is defined at one corner of the intersecting region of the core unit 92. Next, the laser irradiation unit 98 moves the optical waveguide 90 and the laser relative to each other so as to move on the diagonal line of the intersecting region as indicated by the arrow in FIG. The type of laser, irradiation energy, and irradiation frequency are as described above. By removing the constituent material of the core portion in the laser irradiation portion 98, a hollow mirror structure 94 as shown in FIG. 13B is formed.

  When deleting a part of the core portion of the optical waveguide, the above-described processing may be performed only on the core layer including the core portion, or the laminated body in which the clad layer is pressure-bonded to one side of the core layer. You may give from the core layer side. An optical waveguide including the hollow mirror structure according to the present invention is completed by further laminating a cladding layer on the core layer on which the mirror surface is formed. In the case of forming a multilayered crossed waveguide, two or more core layers and three or more cladding layers may be alternately laminated so that the uppermost portion and the lowermost portion are clad layers. Hereinafter, a method (post-irradiation method) suitable for manufacturing an optical waveguide according to the present invention will be described with reference to FIGS.

  First, as shown in FIG. 14, a core film material 100 containing a first photoacid generator having a first absorption maximum wavelength in the ultraviolet region is provided. Next, by irradiating a part of the core film material 100 with a first ultraviolet light having a wavelength including the first absorption maximum wavelength by using, for example, a photomask 120, an irradiation region (clad of the core film material 100) The core layer 110 is formed by causing a difference in refractive index between the portion 102) and the non-irradiated region (core portion 101). Instead of the photomask 120, the core layer 110 may be formed by selectively irradiating the core film material 100 with a laser (not shown) having a wavelength including the first absorption maximum wavelength. A hollow mirror structure that defines the mirror surface can be formed on the core portion 101 of the obtained core layer 110 by the above-described processing method.

  Next, as shown in FIG. 15, a second photoacid generator having a second absorption maximum wavelength different from the first absorption maximum wavelength is formed on at least one surface (both surfaces in FIG. 15) of the core layer 110. The clad film material 200 contained is brought into contact, for example, by bonding. Next, the core layer 110 and the clad film material 200 are thermocompression bonded to each other, thereby obtaining a laminate 230 composed of the core layer 110 and the clad film material 200. Next, for example, by using the wavelength cut filter 220, the entire surface of the multilayer body 230 is irradiated with the second ultraviolet light having a wavelength that includes the second absorption maximum wavelength but does not include the first absorption maximum wavelength. The clad film material 200 is converted into the clad layer 210 and the adhesion between the core layer 110 and the clad layer 210 is improved.

  In the post-irradiation method, it is important that the first photoacid generator contained in the core film material 100 and the second photoacid generator contained in the clad film material 200 are different at the absorption maximum wavelength in ultraviolet light. is there. That is, the first photoacid generator is substantially insensitive to the second ultraviolet light irradiated on the entire surface of the laminate after the thermocompression bonding, and only the second photoacid generator is substantially not. Therefore, it is necessary for the first photoacid generator and the second photoacid generator to be different at the absorption maximum wavelength of ultraviolet light.

  Here, when irradiating the second ultraviolet light having a wavelength including the second absorption maximum wavelength but not including the first absorption maximum wavelength, it is convenient to use the wavelength cut filter 220. The wavelength cut filter shields light having a wavelength shorter than a predetermined wavelength and transmits only light having a wavelength longer than that wavelength. When such a wavelength cut filter is used, the first absorption maximum wavelength is necessarily shorter than the second absorption maximum wavelength. For example, when a 300 nm wavelength cut filter is used, the first photoacid generator is selected so that the first absorption maximum wavelength is shorter than 300 nm, and the second photoacid generator is the second absorption maximum wavelength. It is sufficient to select a film whose length is longer than 300 nm. Of course, the post-irradiation method is not limited to an embodiment using such a wavelength cut filter. The first absorption maximum wavelength may be longer than the second absorption maximum wavelength as long as the first photoacid generator is not substantially sensitive during the entire irradiation of the second ultraviolet light.

  Since the first photoacid generator is substantially insensitive during the entire irradiation with the second ultraviolet light, an acid is generated from the first photoacid generator remaining in the core portion 101 of the core layer 110 to generate the core layer 110. The refractive index difference generated during the formation of the film does not shrink or disappear. That is, the waveguide structure of the core layer is not impaired by the entire irradiation of the second ultraviolet light onto the laminate. On the other hand, since the clad film material 200 has a low Tg before irradiation with ultraviolet light during thermocompression bonding to the core layer 110, the thermocompression bonding process can be performed at a lower temperature and lower pressure. The low temperature and low pressure in the thermocompression bonding process is very significant in that the hollow mirror structure provided in the core portion is not easily crushed. In addition, since the second photoacid generator contained in the clad film material 200 releases acid for the first time when the entire surface of the laminate after the thermocompression bonding process is irradiated with the second ultraviolet light, the clad film is formed before the thermocompression bonding process. The polymerizable group in the material 200 does not react.

  As the core film material 100 for forming the core layer 110, any material conventionally known in the art can be used as long as the refractive index is changed by irradiation with the first ultraviolet light or further heating. These materials may be adopted. For example, a first photoacid generator that is activated by irradiation with the first ultraviolet light to release an acid, and a main chain and an acid that is branched from the main chain and activated by the activated first photoacid generator By the action of the above, it is possible to use a material containing a polymer having a detachable group (detachable pendant group) from which at least a part of the molecular structure can be detached from the main chain.

  Examples of the first photoacid generator include tetrakis (pentafluorophenyl) borate and hexafluoroantimonate, tetrakis (pentafluorophenyl) gallate, aluminate, antimonate, and the like. Examples thereof include borates, gallates, carboranes, and halocarboranes. Examples of such a commercial product of the first photoacid generator include “RHODORSIL (registered trademark, the same shall apply hereinafter) PHOTOINITIATOR 2074 (CAS No. 178233) available from Rhodia USA, Cranberry, New Jersey. No. 72-2), “TAG-372R ((dimethyl (2- (2-naphthyl) -2-oxoethyl) sulfonium tetrakis (pentafluorophenyl) borate) available from Toyo Ink Manufacturing Co., Ltd., Tokyo, Japan. : CAS No. 193957-54-9)), “MPI-103 (CAS No. 87709-41-9)” available from Midori Chemical Co., Tokyo, Japan, Toyo Ink Manufacturing Co., Ltd., Tokyo, Japan "TAG-371 (CAS number 193957-5) available from the company No. 8) ”,“ TTBPS-TPFPB (tris (4-tert-butylphenyl) sulfonium tetrakis (pentapentafluorophenyl) borate) ”available from Toyo Gosei Co., Ltd., Tokyo, Japan, etc. .

  When RHODORSIL PHOTOINITIATOR 2074 is used as the first photoacid generator, a high-pressure mercury lamp or metal halide lamp is preferably used as the first ultraviolet light irradiation means. Thereby, ultraviolet light with sufficient energy of less than 300 nm can be supplied to the core film material 100, and RHODORSIL PHOTOINITIATOR 2074 can be efficiently decomposed to generate the acid.

  The polymer having a leaving group has sufficiently high transparency (colorless and transparent), and the leaving group is released (cleaved) by the action of an acid released by the first photoacid generator, preferably a proton. And the refractive index of which changes (preferably decreases). The leaving group is preferably a group having at least one of an —O— structure, an —Si—aryl structure and an —O—Si— structure in its molecular structure. Such a leaving group is released relatively easily by the action of an acid, preferably a proton. Among these, at least one of the -Si-diphenyl structure and the -O-Si-diphenyl structure is preferable as the leaving group that lowers the refractive index of the polymer by leaving. Examples of such polymers include cyclic olefin resins such as norbornene resins and benzocyclobutene resins, acrylic resins, methacrylic resins, polycarbonates, polystyrenes, epoxy resins, polyamides, polyimides, polybenzoxazoles, and the like. One of these or a combination of two or more thereof (polymer alloy, polymer blend (mixture), copolymer, etc.) can be used. Among these, those mainly composed of norbornene resins (norbornene polymers) are preferable. By using a norbornene-based polymer as the polymer, the core layer 110 having excellent optical transmission performance and heat resistance can be obtained. In addition, since the norbornene-based polymer has high hydrophobicity, it is possible to obtain the core layer 110 that is less likely to cause a dimensional change due to water absorption.

  The norbornene polymer may be either one having a single repeating unit (homopolymer) or one having two or more norbornene repeating units (copolymer). Examples of such norbornene-based polymers include (1) addition (co) polymers of norbornene monomers obtained by addition (co) polymerization of norbornene monomers, and (2) norbornene monomers and ethylene or α-olefins. (3) addition polymers such as addition copolymers with norbornene-type monomers and non-conjugated dienes, and other monomers as required, (4) ring opening of norbornene-type monomers ( A (co) polymer, and a resin obtained by hydrogenating the (co) polymer if necessary, (5) a ring-opening copolymer of a norbornene-type monomer and ethylene or α-olefins, and ( (Co) polymer hydrogenated resin, (6) ring-opening copolymer of norbornene type monomer and non-conjugated diene or other monomer, and (co) polymerization if necessary And a ring-opening polymer such as a polymer obtained by hydrogenating the body. Examples of these polymers include random copolymers, block copolymers, and alternating copolymers.

  These norbornene-based polymers include, for example, ring-opening metathesis polymerization (ROMP), combination of ROMP and hydrogenation reaction, polymerization by radical or cation, polymerization using a cationic palladium polymerization initiator, and other polymerization initiators ( For example, it can be obtained by any known polymerization method such as polymerization using a polymerization initiator of nickel or another transition metal).

  Among these, the norbornene-based polymer is preferably an addition (co) polymer of norbornene-based monomers having at least one repeating unit represented by the following chemical formula 1 (structural formula B). This is particularly preferable because it has the highest transparency and flexibility common to norbornene-based polymers and has the highest heat resistance.

  Such a norbornene polymer is suitably synthesized by using, for example, a norbornene monomer described later (a norbornene monomer or a crosslinkable norbornene monomer described later).

  In order to obtain a polymer having a relatively high refractive index, a monomer having an aromatic ring (aromatic group), a nitrogen atom, a bromine atom or a chlorine atom in the molecular structure is generally selected and the polymer is selected. Is synthesized (polymerized). On the other hand, in order to obtain a polymer having a relatively low refractive index, a monomer having an alkyl group, a fluorine atom, an ether structure (ether group), a siloxane structure or the like is generally selected in the molecular structure, Synthesized (polymerized).

  As the norbornene-based polymer having a relatively high refractive index, those containing a repeating unit of aralkylnorbornene are preferable. Such norbornene-based polymers have a particularly high refractive index. Examples of the aralkyl group (arylalkyl group) of the aralkylnorbornene repeating unit include benzyl group, phenylethyl group, phenylpropyl group, phenylbutyl group, naphthylethyl group, naphthylpropyl group, fluorenylethyl group, fluorene group, and the like. Examples thereof include a nylpropyl group, and a benzyl group and a phenylethyl group are particularly preferable. A norbornene-based polymer having such a repeating unit is preferable because it has a very high refractive index.

  Further, the norbornene-based polymer preferably contains an alkylnorbornene repeating unit. Since a norbornene-based polymer containing an alkylnorbornene repeating unit has high flexibility, high flexibility (flexibility) can be imparted to the optical waveguide by using such norbornene-based polymer. Examples of the alkyl group that the alkylnorbornene repeating unit has include a propyl group, a butyl group, a pentyl group, a hexyl group, a heptyl group, an octyl group, a nonyl group, and a decyl group, and a hexyl group is particularly preferable. These alkyl groups may be either linear or branched.

  By including the repeating unit of hexyl norbornene, it is possible to prevent the refractive index of the entire norbornene-based polymer from being lowered and to maintain high flexibility. Such a norbornene-based polymer is preferable because of its excellent transmittance with respect to light in the wavelength region as described above (particularly in the wavelength region near 850 nm). Preferred examples of such norbornene polymers include hexyl norbornene homopolymer, phenylethyl norbornene homopolymer, benzyl norbornene homopolymer, hexyl norbornene and phenylethyl norbornene copolymer, and hexyl norbornene and benzyl norbornene copolymer. However, it is not limited to these. In particular, as a polymer whose refractive index decreases due to the leaving group leaving, a homopolymer of diphenylmethylnorbornene methoxysilane or a copolymer of hexylnorbornene and diphenylmethylnorbornene methoxysilane is preferably used.

  The core film material 100 for forming the core layer 110 may further contain a monomer and a procatalyst that are compatible with the polymer and have a refractive index different from that of the polymer. In this case, the first photoacid generator further releases a weakly coordinating anion when irradiated with the first ultraviolet light, and the activation temperature of the procatalyst is lowered by the action of the weakly coordinating anion, Furthermore, the monomer can be polymerized by activating the procatalyst by heating to the activation temperature.

  Such a monomer reacts to form a reactant in the irradiation region of the first ultraviolet light, and the presence of this reactant causes a refractive index difference between the irradiated region and the unirradiated region in the core layer 110. The resulting compound. The reactants include a polymer formed by polymerizing monomers in a polymer (matrix), a crosslinked structure that crosslinks the polymers, and a branched structure that is polymerized and branched from the polymer (branched polymer). And at least one of side chains (pendant groups)).

  Here, in the core layer 110, when it is desired that the refractive index of the irradiated region be high, a polymer having a relatively low refractive index and a monomer having a high refractive index for this polymer are used in combination. When it is desired that the refractive index of the irradiated region be low, a polymer having a relatively high refractive index and a monomer having a low refractive index for this polymer are used in combination. Note that “high” or “low” in the refractive index does not mean the absolute value of the refractive index but means a relative relationship between certain materials. Then, when the refractive index of the irradiated region in the core layer 110 decreases due to the monomer reaction (reactant generation), the portion becomes the cladding portion 102, and when the refractive index of the irradiated region increases, the portion becomes the core portion. 101.

  Such a monomer is not particularly limited as long as it is a compound having a polymerizable site, and examples thereof include norbornene monomers, acrylic acid (methacrylic acid) monomers, epoxy monomers, styrene monomers, and the like. These can be used alone or in combination of two or more. Among these, it is preferable to use a norbornene-based monomer as the monomer. By using the norbornene-based monomer, it is possible to obtain the core layer 110 (optical waveguide element) having excellent optical transmission performance and excellent heat resistance and flexibility. The norbornene-based monomer is a generic term for monomers containing at least one norbornene skeleton represented by the following structural formula A, and examples thereof include compounds represented by the following structural formula C.

In the above formula, a represents a single bond or a double bond, R ^{1 to} R ⁴ each independently represents a hydrogen atom, a substituted or unsubstituted hydrocarbon group, or a functional substituent, and m is Represents an integer of 0 to 5; However, when a is a double bond, either one of R ¹ and R ² or one of R ³ and R ⁴ does not exist.

Examples of the unsubstituted hydrocarbon group (hydrocarbyl group) include, for example, a linear or branched alkyl group having 1 to 10 carbon atoms (C _{1 to} C ₁₀ ), a linear or branched carbon number of 2 -10 (C ₂ -C ₁₀ alkenyl group, linear or branched alkynyl group having 2 to 10 carbon atoms (C ₂ -C ₁₀ ), cycloalkyl having 4 to 12 carbon atoms (C ₄ -C ₁₂ ) Group, C 4-12 (C ₄ -C ₁₂ ) cycloalkenyl group, C 6-12 (C ₆ -C ₁₂ ) aryl group, C 7-24 (C ₇ -C ₂₄ ) aralkyl group In addition, R ¹ and R ² , R ³ and R ⁴ may each be an alkylidenyl group having 1 to 10 carbon atoms (C _{1 to} C ₁₀ ).

  Specific examples of the alkyl group include methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, sec-butyl group, tert-butyl group, pentyl group, neopentyl group, hexyl group, heptyl group, octyl group. , Nonyl and decyl groups, but are not limited thereto. Specific examples of the alkenyl group include, but are not limited to, a vinyl group, an allyl group, a butenyl group, and a cyclohexenyl group. Specific examples of the alkynyl group include, but are not limited to, ethynyl group, 1-propynyl group, 2-propynyl group, 1-butynyl group and 2-butynyl group. Specific examples of the cycloalkyl group include, but are not limited to, a cyclopentyl group, a cyclohexyl group, and a cyclooctyl group. Specific examples of the aryl group include, but are not limited to, a phenyl group, a naphthyl group, and an anthracenyl group. Specific examples of the aralkyl group include, but are not limited to, a benzyl group and a phenylethyl (phenethyl) group. Further, specific examples of the alkylidenyl group include, but are not limited to, a methylidenyl group and an ethylidenyl group.

Examples of the substituted hydrocarbon group include those in which some or all of the hydrogen atoms of the hydrocarbon group are substituted with a halogen atom, that is, a halohydrocarbyl group, a perhalohydrocarbyl group. Or halogenated hydrocarbon groups such as perhalocarbyl groups. In these halogenated hydrocarbon groups, the halogen atom substituted with a hydrogen atom is preferably at least one selected from a chlorine atom, fluorine and bromine, more preferably a fluorine atom. Among these, specific examples of the perhalogenated hydrocarbon group (perhalohydrocarbyl group, perhalocarbyl group) include, for example, a perfluorophenyl group, a perfluoromethyl group (trifluoromethyl group), and a perfluoroethyl group. Perfluoropropyl group, perfluorobutyl group, perfluorohexyl group and the like. As the halogenated alkyl group, those having 11 to 20 carbon atoms can be suitably used in addition to those having 1 to 10 carbon atoms. That is, as the halogenated alkyl group, a group that is partially or completely halogenated, linear or branched, and represented by the general formula: —C _Z X ″ _{2Z + 1} can be selected. Here, X '' represents a halogen atom or a hydrogen atom each independently, and Z represents the integer of 1-20. In addition to the halogen atom, the substituted hydrocarbon group may be a linear or branched alkyl group having 1 to 5 carbon atoms (C _{1 to} C ₅ ), a haloalkyl group, an aryl group, and a cycloalkyl group. Examples thereof include a substituted cycloalkyl group, aryl group, and aralkyl group (aralkyl group).

Moreover, as a functional substituent, for example, — (CH ₂ ) _n —CH (CF ₂ ) ₂ —O—Si (Me) ₃ , — (CH ₂ ) _n —CH (CF ₃ ) ₂ —O—CH ₂ —O—CH ₃ , — (CH ₂ ) _n —CH (CF ₃ ) ₂ —O—C (O) —O—C (CH ₃ ) ₃ , — (CH ₂ ) _n —C (CF ₃ ) ₂ — OH, — (CH ₂ ) _n —C (O) —NH ₂ , — (CH ₂ ) _n —C (O) —Cl, — (CH ₂ ) _n —C (O) —O—R ⁵ , — ( CH ₂ ) _n —O—R ⁵ , — (CH ₂ ) _n —O—C (O) —R ⁵ , — (CH ₂ ) _n —C (O) —R ⁵ , — (CH ₂ ) _n —O —C (O) —OR ⁵ , — (CH ₂ ) _n —Si (R ⁵ ) ₃ , — (CH ₂ ) _n —Si (OR ⁵ ) ₃ , — (CH ₂ ) _n —O—Si (R ⁵⁾ ) _3, and - ( _{H 2) n -C (O)} -OR 6 , and the like. Here, in each of the formulas above, each, n is an integer of 0, ^{R 5} are each independently a hydrogen atom, a linear or branched C 1 to 20 _(C 1 -C ₂₀₎ alkyl group, a linear or branched halogenated or perhalogenated alkyl group having a carbon number 1 to 20 _(C 1 _{-C 20)} linear or branched C 2 to 10 _(C 2 ~ alkenyl group of C _10), a linear or branched alkynyl group having 2 to 10 carbon atoms _(C 2 _{~C 10),} a cycloalkyl group having 5 to 12 carbon atoms _(C 5 _{~C 12),} to 6 carbon atoms -14 (C ₆ -C ₁₄ ) aryl group, C 6-14 (C ₆ -C ₁₄ ) halogenated or perhalogenated aryl group or C 7-24 (C ₇ -C ₂₄ ) aralkyl group Represents. Incidentally, the hydrocarbon group represented by R ⁵ represents the same hydrocarbon groups as those represented by R ¹ to R ^4. As represented by R ^{1 to} R ⁴ , the hydrocarbon group represented by R ⁵ may be halogenated or perhalogenated. For example, when R ⁵ is a halogenated or perhalogenated alkyl group having 1 to 20 carbon atoms (C _{1 to} C ₂₀ ), R ⁵ is represented by the general formula: —C _Z X ″ _{2Z + 1} . Here, z and X ″ are the same as defined above, and at least one of X ″ is a halogen atom (for example, a bromine atom, a chlorine atom, or a fluorine atom). Here, the perhalogenated alkyl group is a group in which all X ″ are halogen atoms in the above general formula, and specific examples thereof include a trifluoromethyl group, a trichloromethyl group, —C ₇ F _15. Although _-C 11 _{F 23} and the like, but are not limited to. Specific examples of the perhalogenated aryl group include, but are not limited to, a pentachlorophenyl group and a pentafluorophenyl group. Examples of R ⁶ include —C (CH ₃ ) ₃ , —Si (CH ₃ ) ₃ , —CH (R ⁷ ) —O—CH ₂ CH ₃ , —CH (R ⁷ ) OC (CH ₃ ). ₃ and the cyclic group of the following chemical formula 4 and the like.

Here, R ⁷ represents a hydrogen atom or a linear or branched alkyl group having ₁ to ₅ carbon atoms (C _{1 to} C ₅ ). Examples of the alkyl group include methyl group, ethyl group, propyl group, i-propyl group, butyl group, i-butyl group, t-butyl, pentyl group, t-pentyl group, and neopentyl group. In the cyclic group represented by Chemical Formula 4, an ester bond is formed between the single bond extending from the ring structure and the acid substituent. Specific examples of R6 include 1-methyl-1-cyclohexyl group, isobornyl group, 2-methyl-2-isobornyl group, 2-methyl-2-adamantyl group, tetrahydrofuranyl group, tetrahydrofuranyl group, and the like. A pyranoyl group, a 3-oxocyclohexanoyl group, a mevalonic lactonyl group, a 1-ethoxyethyl group, a 1-t-butoxyethyl group, and the like can be given. Other examples of R ⁶ include a dicyclopropylmethyl group (Dcpm) and a dimethylcyclopropylmethyl group (Dmcp) represented by the following chemical formula 5.

  Moreover, it can replace with said monomer for a monomer, or can also use a crosslinkable monomer (crosslinking agent) with said monomer. This crosslinkable monomer is a compound capable of causing a crosslinking reaction in the presence of a catalyst precursor described later. The use of the crosslinkable monomer has the following advantages. That is, since the crosslinkable monomer is polymerized faster, the time required for forming (process) the core layer 110 can be shortened. Moreover, since the crosslinkable monomer is difficult to evaporate even when heated, an increase in vapor pressure can be suppressed. Furthermore, since the crosslinkable monomer is excellent in heat resistance, the heat resistance of the core layer 110 can be improved.

  Among these, the crosslinkable norbornene-based monomer is a compound including a norbornene-based portion (norbornene-based double bond) represented by the structural formula A. As the crosslinkable norbornene-based monomer, there are a compound of a continuous polycyclic ring system and a compound of a linked multicyclic ring system. Examples of the continuous polycyclic ring-based compound (continuous polycyclic ring-based crosslinkable norbornene-based monomer) include the following compounds.

In the above formula, Y represents a methylene (—CH ₂ —) group, and m represents an integer of 0 to 5. However, when m is 0, Y is a single bond. For simplicity, norbornadiene is considered to be included in a continuous polycyclic ring system and includes a polymerizable norbornene double bond. Specific examples of the compound having the continuous polycyclic ring system include, but are not limited to, the following compounds.

  On the other hand, examples of the linked polycyclic ring-based compound (linked polycyclic ring-based crosslinkable norbornene-based monomer) include the following compounds.

In the above formulae, each a independently represents a single bond or a double bond, each m independently represents an integer of 0 to 5, and each R9 independently represents a divalent hydrocarbon group. Represents a divalent ether group or a divalent silyl group. N is 0 or 1. Here, the divalent substituent refers to a group having two bonds that can be bonded to the norbornene structure at the end. Specific examples of the divalent hydrocarbon group (hydrocarbyl group) include an alkylene group represented by the general formula:-(C _d H _2d )-(d is preferably an integer of 1 to 10). And a divalent aromatic group (aryl group). The divalent alkylene group is preferably a linear or branched alkylene group having 1 to 10 carbon atoms (C _{1 to} C ₁₀ ), such as a methylene group, an ethylene group, a propylene group, a butylene group, a pentylene group, Examples include a hexylene group, a heptylene group, an octylene group, a nonylene group, and a decylene group. The branched alkylene group is one in which a main chain hydrogen atom is substituted with a linear or branched alkyl group. On the other hand, the divalent aromatic group is preferably a divalent phenyl group or a divalent naphthyl group. The divalent ether group is a group represented by —R ¹⁰ —O—R ¹⁰ —. Here, R ¹⁰ independently represents the same as R ⁹ . Specific examples of this linked polycyclic ring compound include compounds represented by the following chemical formula 9, chemical formula 10, chemical formula 11, chemical formula 12, chemical formula 13, and fluorine-containing compounds represented by chemical formulas 14 and 15 ( Fluorine-containing crosslinkable norbornene-based monomer), but is not limited thereto.

  The compound represented by the chemical formula 10 is dimethylbis [bicyclo [2.2.1] hept-2-ene-5-methoxy] silane, and is named dimethylbis (norbornenemethoxy) silane (“ Abbreviated as “SiX”).

  In the above formula, n represents an integer of 0 to 4.

  In the above formula, m and n each represent an integer of 1 to 4.

  Among various crosslinkable norbornene monomers, dimethylbis (norbornenemethoxy) silane (SiX) is particularly preferable. SiX has a sufficiently low refractive index with respect to a norbornene-based polymer containing a repeating unit of alkylnorbornene and / or a repeating unit of aralkylnorbornene. For this reason, the refractive index of the irradiation region irradiated with the first ultraviolet light to be described later can be reliably lowered to form the clad portion 102. Moreover, the refractive index difference between the core part 101 and the clad part 102 can be increased, and the characteristics (optical transmission performance) of the core layer 110 can be improved. In addition, you may make it use the above monomers individually or in arbitrary combinations.

  Procatalyst is a substance capable of initiating the above-mentioned monomer reaction (polymerization reaction, crosslinking reaction, etc.), and is activated at the activation temperature by the action of the first photoacid generator activated by irradiation with the first ultraviolet light. Is a changing substance.

  As this procatalyst (also referred to as a catalyst precursor), any compound may be used as long as the activation temperature changes (increases or decreases) with irradiation of the first ultraviolet light. Those whose activation temperature decreases with irradiation of the first ultraviolet light are preferred. As a result, the core layer 110 can be formed by heat treatment at a relatively low temperature, and unnecessary heat is applied to the other layers, thereby preventing deterioration of the characteristics (optical transmission performance) of the optical waveguide. .

As such a procatalyst, those containing (mainly) at least one of the compounds represented by the following formulas (Ia) and (Ib) are preferably used.
(E (R) ₃ ) ₂ Pd (Q) ₂ (Ia)
[(E (R) ₃ ) _a Pd (Q) (LB) _b ] _p [WCA] _r (Ib)
In formulas Ia and Ib, E (R) ₃ represents a neutral electron donor ligand of group 15, respectively, E represents an element selected from group 15 of the periodic table, and R represents It represents a moiety containing a hydrogen atom (or one of its isotopes) or a hydrocarbon group, Q represents an anionic ligand selected from carboxylate, thiocarboxylate and dithiocarboxylate. In Formula Ib, LB represents a Lewis base, WCA represents a weakly coordinating anion, a represents an integer of 1 to 3, b represents an integer of 0 to 2, and a and b , P and r represent numbers that balance the charge of the palladium cation and the weakly coordinated anion.

Typical procatalysts according to Formula Ia include Pd (OAc) ₂ (P (i-Pr) ₃ ) ₂ , Pd (OAc) ₂ (P (Cy) ₃ ) ₂ , Pd (O ₂ CCMe ₃ ) ₂ ( P (Cy) ₃ ) ₂ , Pd (OAc) ₂ (P (Cp) ₃ ) ₂ , Pd (O ₂ CCF ₃ ) ₂ (P (Cy) ₃ ) ₂ , Pd (O ₂ CC ₆ H ₅ ) ₃ ( P (Cy) ₃ ) ₂ may be mentioned, but is not limited thereto. Here, Cp represents a cyclopentyl group, and Cy represents a cyclohexyl group.

The procatalyst represented by the formula Ib is preferably a compound in which p and r are selected from integers of 1 and 2, respectively. A typical procatalyst according to such a formula Ib includes Pd (OAc) ₂ (P (Cy) ₃ ) ₂ . Here, Cy represents a cyclohexyl group, and Ac represents an acetyl group.

  These procatalysts can efficiently react with a monomer (in the case of a norbornene-based monomer, an efficient polymerization reaction, a crosslinking reaction, etc. by an addition polymerization reaction).

Further, in a state where the activation temperature is lowered (active latent state), as a procatalyst, the activation temperature is lower by about 10 to 80 ° C. (preferably about 10 to 50 ° C.) than the original activation temperature. Those are preferred. Thereby, the refractive index difference between the core part 101 and the clad part 102 can be produced reliably. As such a procatalyst, one containing (mainly) at least one of Pd (OAc) ₂ (P (i-Pr) ₃ ) ₂ and Pd (OAc) ₂ (P (Cy) ₃ ) ₂ is preferable. It is. Hereinafter, Pd (OAc) ₂ (P (i-Pr) ₃ ) ₂ may be abbreviated as “Pd545”, and Pd (OAc) ₂ (P (Cy) ₃ ) ₂ may be abbreviated as “Pd785”. .

  In forming the core film material 100, a varnish for the core containing the polymer, the first photoacid generator, and other required additives is prepared. Examples of the solvent used for the preparation of the core varnish include diethyl ether, diisopropyl ether, 1,2-dimethoxyethane (DME), 1,4-dioxane, tetrahydrofuran (THF), tetrahydropyran (THP), anisole, diethylene glycol dimethyl ether. (Diglyme), ether solvents such as diethylene glycol ethyl ether (carbitol), cellosolve solvents such as methyl cellosolve, ethyl cellosolve, phenyl cellosolve, aliphatic hydrocarbon solvents such as hexane, pentane, heptane, cyclohexane, toluene, xylene , Aromatic hydrocarbon solvents such as benzene and mesitylene, aromatic heterocyclic compounds solvents such as pyridine, pyrazine, furan, pyrrole, thiophene and methylpyrrolidone, N, N-dimethylform Amide solvents such as amide (DMF) and N, N-dimethylacetamide (DMA), halogen compound solvents such as dichloromethane, chloroform and 1,2-dichloroethane, ester solvents such as ethyl acetate, methyl acetate and ethyl formate, Examples include various organic solvents such as sulfur compound solvents such as dimethyl sulfoxide (DMSO) and sulfolane, and mixed solvents containing these.

  Moreover, you may add a sensitizer to the varnish for cores as needed. The sensitizer increases the sensitivity of the first photoacid generator with respect to the first ultraviolet light, reduces the time and energy required for activation (reaction or decomposition), and a wavelength suitable for the activation. And a function of changing the wavelength of the first ultraviolet light. Such a sensitizer is appropriately selected according to the sensitivity of the photoacid generator and the peak wavelength of absorption of the sensitizer, and is not particularly limited. For example, 9,10-dibutoxyanthracene (CAS No. 76275-14-4) anthracenes, xanthones, anthraquinones, phenanthrenes, chrysene, benzpyrenes, fluoranthenes, rubrenes, pyrenes, indanthrines, thioxanthene-9- Examples thereof include thixanthen-9-ones, and these are used alone or as a mixture. Specific examples of the sensitizer include 2-isopropyl-9H-thioxanthen-9-one, 4-isopropyl-9H-thioxanthen-9-one, 1-chloro-4-propoxythioxanthone, phenothiazine, and these Of the mixture. 9,10-dibutoxyanthracene (DBA) can be obtained from Kawasaki Kasei Kogyo Co., Ltd., Kanagawa, Japan. The content of the sensitizer in the core varnish is not particularly limited, but is preferably 0.01% by mass or more, more preferably 0.5% by mass or more, and 1% by mass or more. Is more preferable. In addition, it is preferable that an upper limit is 5 mass% or less.

  Furthermore, you may add antioxidant to the varnish for cores as needed. Thereby, generation of undesirable free radicals and natural oxidation of the polymer can be prevented. As a result, the characteristics of the obtained core layer 110 can be improved. Examples of the antioxidant include Ciba (registered trademark, the same applies hereinafter) IRGANOX (registered trademark, the same applies hereinafter) 1076 and Ciba IRGAFOS (registered trademark, available) from Ciba Specialty Chemicals of Tarrytown, New York. The same applies hereinafter.) 168 is preferably used. Other antioxidants include, for example, Ciba Irganox (registered trademark, hereinafter the same) 129, Ciba Irganox 1330, Ciba Irganox 1010, Ciba Cyanox (registered trademark, the same shall apply) 1790, Ciba Igan. (Registered trademark) 3114, Ciba Irganox 3125, etc. can also be used.

  The core varnish has a viscosity (room temperature) of preferably about 100 to 10000 cP, more preferably about 150 to 5000 cP, and still more preferably about 200 to 3500 cP, depending on the coating method described below and the desired film thickness. It can be prepared by adjusting the amount of solvent as appropriate.

  The core film material 100 can be formed by applying the above-described core varnish on a support substrate. As the support substrate, for example, a silicon substrate, a silicon dioxide substrate, a glass substrate, a quartz substrate, a polyethylene terephthalate (PET) film, or the like is used. Examples of the coating method include, but are not limited to, a doctor blade method, a spin coating method, a dipping method, a table coating method, a spray method, an applicator method, a curtain coating method, and a die coating method. Although there is no limitation in particular in the thickness of a coating film, about 5-200 micrometers in the state before drying, Preferably it is about 15-125 micrometers, More preferably, what is necessary is just to be about 25-100 micrometers.

  Next, the core film material 100 can be obtained by removing (desolving) the solvent in the coating film, that is, drying. Examples of the solvent removal (drying) method include heating, leaving under atmospheric pressure or reduced pressure, and spraying (blowing) an inert gas. For example, a method using heating using a hot plate Is preferred. This makes it possible to remove the solvent relatively easily and in a short time. When heating, it is preferable that heating temperature is about 25-60 degreeC, and it is more preferable that it is about 30-45 degreeC. Further, the heating time is preferably about 15 to 60 minutes, more preferably about 15 to 30 minutes.

  The obtained core film material 100 can be selectively irradiated with the first ultraviolet light without being peeled from the support substrate. As a method of selectively irradiating the first ultraviolet light, a mask (masking) 120 in which an opening (window) is formed is prepared, and the first ultraviolet light is applied to the core film material 100 through the mask 120. Can be irradiated. In the example shown in FIG. 14, the irradiation region of the first ultraviolet light is the clad portion 102. Accordingly, an opening (window) equivalent to the pattern of the clad portion 102 to be formed is formed in the mask 120. This opening forms a transmission part through which the first ultraviolet light to be irradiated passes.

  The mask 120 may be formed in advance (separately formed) (for example, plate-shaped) or may be formed on the core film material 100 by, for example, a vapor deposition method or a coating method. Examples of preferable mask 120 include a photomask made of quartz glass or a PET base material, a stencil mask, a metal thin film formed by a vapor deposition method (evaporation, sputtering, etc.), etc. Among these, it is particularly preferable to use a photomask or a stencil mask. This is because a fine pattern can be formed with high accuracy, and handling is easy, which is advantageous in improving productivity.

The first ultraviolet light to be used may be any one that can cause a photochemical reaction (change) to the first photoacid generator. In particular, the first ultraviolet light is appropriately selected depending on the type of the first photoacid generator used and, if it contains a sensitizer, the peak of the wavelength in the range of 200 to 450 nm. It is preferable to use one having a wavelength. The irradiation amount of the first ultraviolet light is preferably in the range of about 0.1~9J / cm ^2, more preferably about 0.2~6J / cm ^2, 0.2~3J / cm More preferably, it is about ² . Thereby, a 1st photo-acid generator can be activated reliably.

When the core film material 100 is irradiated with the first ultraviolet light through the mask 120, the release agent present in the irradiation region irradiated with the first ultraviolet light reacts (bonds) by the action of the first ultraviolet light. ) Or decompose to liberate (generate) cations (protons or other cations) and weakly coordinating anions (WCA). Then, the cation causes the leaving group itself to leave the main chain, or cleaves from the middle of the molecular structure of the leaving group (photo bleach). Thereby, in the irradiated region, the number of the leaving groups in a complete state is decreased as compared with the non-irradiated region, and the second refractive index lower than the first refractive index is lowered. At this time, the refractive index of the unirradiated region 940 is maintained at the first refractive index. In this way, a refractive index difference (second refractive index <first refractive index) occurs between the irradiated region and the unirradiated region, and the core portion 101 (unirradiated region) and the cladding portion 102 (irradiated region). ) And are formed. In this case, the irradiation amount of the first ultraviolet light is preferably in the range of about 0.1~9J / cm ^2, more preferably about 0.3~6J / cm ^2, 0.6~ More preferably, it is about 6 J / cm ² . Thereby, a release agent can be activated reliably.

  Next, heat treatment is performed on the core film material 100 as necessary. By the heat treatment, the leaving group detached (cut) from the polymer is removed from, for example, the irradiated region, or rearranged or crosslinked in the polymer. Further, at this time, it is considered that a part of the leaving group remaining in the clad portion 102 (irradiation region) is further detached (cut). Therefore, the refractive index difference between the core portion 101 and the clad portion 102 can be further increased by performing such heat treatment. Although the heating temperature in this heat processing is not specifically limited, It is preferable that it is about 70-195 degreeC, and it is more preferable that it is about 85-150 degreeC. The heating time is set so as to sufficiently remove the leaving group that has been detached (cleaved) from the irradiation region, and is not particularly limited, but is preferably about 0.5 to 3 hours, 0.5 to More preferably, it is about 2 hours. Moreover, the process of 1 time or several times of heat processing (for example, about 150-200 degreeC x about 1 to 8 hours) can also be added as needed. For example, when a sufficient refractive index difference is obtained between the core portion 101 and the clad portion 102 in a state before the heat treatment, such a heating step can be omitted. . Through the above steps, the core layer 110 including the core portion 101 and the clad portion 102 is formed. Thereafter, the core layer 110 is peeled from the support substrate.

  In a preferred embodiment, the core portion 101 and the clad portion 102 are composed of a norbornene polymer having a main chain and a main chain branched from the main chain and having a leaving group capable of leaving at least a part of the molecular structure from the main chain. The core part 101 and the clad part 102 have different refractive indexes due to the difference in the number of leaving groups bonded to the main chain.

  When the core film material 100 further contains a monomer and a procatalyst that are compatible with the polymer and have a refractive index different from that of the polymer, the first ultraviolet light is passed through the mask 120. When 100 is irradiated, the first photoacid generator present in the irradiation region irradiated with the first ultraviolet light reacts or decomposes by the action of the first ultraviolet light, and becomes a cation (proton or other positive light). Ions) and weakly coordinating anions (WCA) are released (generated). These cations and weakly coordinating anions cause a change (decomposition) in the molecular structure of the procatalyst existing in the irradiation region, and change this into an active latent state (latent active state). Here, an active latent state (or potential active state) procatalyst has an activation temperature that is lower than the original activation temperature, but there is no temperature increase, that is, within the irradiation region at room temperature. The catalyst precursor in a state in which the reaction of the monomer cannot occur. Therefore, even after the first ultraviolet light irradiation, if the core film material 100 is stored at, for example, about −40 ° C., the state can be maintained without causing a monomer reaction. For this reason, it is highly convenient in that the core layer 110 can be obtained by preparing a plurality of core film materials 100 after the first ultraviolet light irradiation and subjecting them to heat treatment in a lump.

  Note that the use of the mask 120 may be omitted when light having high directivity such as laser light is used as the first ultraviolet light.

  Next, heat treatment (first heat treatment) is performed on the core film material 100. Thereby, in the irradiation region, the active catalyzed procatalyst is activated (becomes active), and monomer reaction (polymerization reaction or crosslinking reaction) occurs. As the monomer reaction proceeds, the monomer concentration in the irradiated region gradually decreases. As a result, there is a difference in monomer concentration between the irradiated region and the unirradiated region, and in order to eliminate this, the monomer diffuses from the unirradiated region and collects in the irradiated region. As a result, in the irradiated region, the monomer and its reactant (polymer, cross-linked structure or branched structure) increase, and the structure derived from the monomer greatly affects the refractive index of the region, and the first refractive index Lower to a lower second refractive index. As the monomer polymer, an addition (co) polymer is mainly produced. On the other hand, in the unirradiated region, the amount of monomer decreases due to the diffusion of the monomer from the region to the irradiated region, so that the influence of the polymer greatly appears in the refractive index of the region, which is higher than the first refractive index. It rises to the third refractive index. In this way, a refractive index difference (second refractive index <third refractive index) occurs between the irradiated region and the unirradiated region, and the core portion 101 (unirradiated region) and the cladding portion 102 (irradiated region). ) And are formed.

  Although the heating temperature in this heat processing is not specifically limited, It is preferable that it is about 30-80 degreeC, and it is more preferable that it is about 40-60 degreeC. Further, the heating time is preferably set so that the reaction of the monomer in the irradiated region is almost completed. Specifically, the heating time is preferably about 0.1 to 2 hours, preferably about 0.1 to 1 hour. It is more preferable that

  Next, a second heat treatment is performed on the core film material 100. As a result, the non-irradiated region and / or the procatalyst remaining in the irradiated region is activated (activated) directly or with the activation of the first photoacid generator, thereby remaining in each region. The monomer to be reacted is reacted. In this way, by reacting the monomer remaining in each region, the core portion 101 and the clad portion 102 obtained can be stabilized.

  The heating temperature in the second heat treatment is not particularly limited as long as it is a temperature capable of activating the procatalyst or the first photoacid generator, but is preferably about 70 to 100 ° C., 80 to 90 It is more preferable that the temperature is about ° C. The heating time is preferably about 0.5 to 2 hours, more preferably about 0.5 to 1 hour.

  Next, a third heat treatment is performed on the core film material 100. Thereby, reduction of the internal stress which arises in the core layer 110 obtained, and the further stabilization of the core part 101 and the clad part 102 can be aimed at.

  The heating temperature in the third heat treatment is preferably set to 20 ° C. or more higher than the heating temperature in the second heat treatment, specifically, preferably about 90 to 180 ° C., 120 to 160 ° C. More preferred is the degree. The heating time is preferably about 0.5 to 2 hours, more preferably about 0.5 to 1 hour. Through the above steps, the core layer 110 including the core portion 101 and the clad portion 102 is formed. Thereafter, the core layer 110 is peeled from the support substrate.

  Examples of the clad film material 200 for forming the clad layer 210 include acrylic resin, methacrylic resin, polycarbonate, polystyrene, epoxy resin, polyamide, polyimide, polybenzoxazole, benzocyclobutene resin, norbornene resin, and the like. These can be used in combination of one or more of them (polymer alloy, polymer blend (mixture), copolymer, composite (laminate), etc.). Of these, epoxy resins, polyimides, polybenzoxazoles, cyclic olefin resins such as benzocyclobutene resins and norbornene resins, and those containing them (mainly) in terms of particularly excellent heat resistance It is preferable to use, and particularly, those mainly composed of norbornene-based resins (norbornene-based polymers) are preferable.

  Since the norbornene-based polymer has extremely high heat resistance, in the optical waveguide 240 using this as a constituent material of the cladding layer 210, when forming a conductor layer (not shown) in the optical waveguide 240, the conductor layer is processed. Even when the wiring is formed and heated when the optical element is mounted, the cladding layer 210 can be prevented from being softened and deformed. In addition, since the norbornene-based polymer has high hydrophobicity, it is possible to obtain the clad layer 210 that is less likely to cause a dimensional change due to water absorption. Furthermore, the norbornene polymer or the norbornene monomer that is a raw material thereof is preferable because it is relatively inexpensive and easily available.

  If a material mainly composed of a norbornene-based polymer is used as the material of the clad layer 210, it becomes the same kind as the material suitably used as the constituent material of the core layer 110, so that the adhesion with the core layer 110 is further increased. Delamination between the clad layer 210 and the core layer 110 can be prevented. For this reason, the optical waveguide 240 having excellent durability can be obtained.

  Examples of such norbornene-based polymers include (1) addition (co) polymers of norbornene monomers obtained by addition (co) polymerization of norbornene monomers, and (2) norbornene monomers and ethylene or α-olefins. (3) addition polymers such as addition copolymers with norbornene-type monomers and non-conjugated dienes, and other monomers as required, (4) ring opening of norbornene-type monomers ( A (co) polymer, and a resin obtained by hydrogenating the (co) polymer if necessary, (5) a ring-opening copolymer of a norbornene-type monomer and ethylene or α-olefins, and ( (Co) polymer hydrogenated resin, (6) ring-opening copolymer of norbornene type monomer and non-conjugated diene or other monomer, and (co) polymerization if necessary And a ring-opening polymer such as a polymer obtained by hydrogenating the body. Examples of these polymers include random copolymers, block copolymers, and alternating copolymers.

  These norbornene-based polymers include, for example, ring-opening metathesis polymerization (ROMP), combination of ROMP and hydrogenation reaction, polymerization by radical or cation, polymerization using a cationic palladium polymerization initiator, and other polymerization initiators ( For example, it can be obtained by any known polymerization method such as polymerization using a polymerization initiator of nickel or another transition metal). Among these, as the norbornene-based polymer, an addition (co) polymer is preferable. This is preferable because it is rich in transparency, heat resistance and flexibility. In particular, the norbornene-based polymer preferably includes a norbornene repeating unit having a substituent containing a polymerizable group or a norbornene repeating unit having a substituent containing an aryl group.

  By including a norbornene repeating unit having a substituent containing a polymerizable group, at least a part of the norbornene-based polymer in the cladding layer 210 can be crosslinked directly or via a crosslinking agent. . Depending on the type of polymerizable group, the type of crosslinking agent, the type of polymer used for the core layer 110, the norbornene-based polymer and the polymer used for the core layer 110 can be cross-linked. In other words, it is preferable that at least a part of the norbornene-based polymer is crosslinked at the polymerizable group. As a result, the strength of the cladding layer 210 itself and the adhesion between the cladding layer 210 and the core layer 110 can be further improved.

  Examples of the norbornene repeating unit containing a polymerizable group include a norbornene repeating unit having a substituent containing an epoxy group, a norbornene repeating unit having a substituent containing a (meth) acryl group, and an alkoxysilyl group. At least one of the repeating units of norbornene having a substituent to be included is preferable. These polymerizable groups are preferable because of their high reactivity among various polymerizable groups. Moreover, if the thing containing 2 or more types of norbornene repeating units containing such a polymeric group is used, a crosslinking density can be improved further and the said effect will become more remarkable.

  On the other hand, by including a norbornene repeating unit having a substituent containing an aryl group, the aryl group has extremely high hydrophobicity, so that a dimensional change due to water absorption of the clad layer 210 can be more reliably prevented. In addition, since the aryl group is excellent in fat solubility (lipophilicity) and has a high affinity with the polymer used for the core layer 110 as described above, delamination between the clad layer 210 and the core layer 110 is further improved. An optical waveguide 240 that can be reliably prevented and is more durable is obtained.

  Furthermore, the norbornene-based polymer preferably contains an alkylnorbornene repeating unit. The alkyl group may be linear or branched. By including the repeating unit of alkyl norbornene, the norbornene-based polymer has high flexibility, so that high flexibility (flexibility) can be imparted to the clad layer 210.

  A norbornene-based polymer containing an alkylnorbornene repeating unit is also preferable because of its excellent transmittance for light in the wavelength region as described above (particularly in the wavelength region near 850 nm).

  The norbornene-based polymer used for the clad layer 210 is preferably a polymer having a relatively low refractive index, whereas if it contains a norbornene repeating unit having a substituent containing an aryl group, the refractive index generally increases. Although it shows a tendency, an increase in the refractive index can be prevented by including a repeating unit of alkyl norbornene.

  Therefore, as the norbornene-based polymer used for the clad layer 210, those represented by the following chemical formulas 16 to 19 and chemical formula 23 are preferable.

  In the above formula, R represents an alkyl group having 1 to 10 carbon atoms, a represents an integer of 0 to 3, b represents an integer of 1 to 3, and p / q is 20 or less. Among the norbornene-based polymers represented by the above chemical formula 16, in particular, R is an alkyl group having 4 to 10 carbon atoms, and a and b are each 1, for example, a copolymer of butylbornene and methylglycidyl ether norbornene, A copolymer of hexyl norbornene and methyl glycidyl ether norbornene, a copolymer of decyl norbornene and methyl glycidyl ether norbornene, and the like are preferable.

In the above formula, R represents an alkyl group having 1 to 10 carbon atoms, R ¹ represents a hydrogen atom or a methyl group, a represents an integer of 0 to 3, and p / q is 20 or less. Among the norbornene-based polymers represented by the above chemical formula 17, in particular, R is an alkyl group having 4 to 10 carbon atoms and a is 1, for example, butylbornene and 2- (5-norbornenyl) methyl acrylate, And a copolymer of hexylnorbornene and 2- (5-norbornenyl) methyl acrylate, a copolymer of decylnorbornene and 2- (5-norbornenyl) methyl acrylate, and the like.

  In the above formula, R represents an alkyl group having 1 to 10 carbon atoms, X represents each independently an alkyl group having 1 to 3 carbon atoms, a represents an integer of 0 to 3, and p / q is 20 or less. Among the norbornene-based polymers represented by the above chemical formula 20, in particular, a compound in which R is an alkyl group having 4 to 10 carbon atoms, a is 1 or 2, and X is a methyl group or an ethyl group, such as butylbornene and norbornene. Copolymers of bornenylethyltrimethoxysilane, copolymers of hexylnorbornene and norbornenylethyltrimethoxysilane, copolymers of decylnorbornene and norbornenylethyltrimethoxysilane, copolymers of butylbornene and triethoxysilylnorbornene, hexylnorbornene Copolymer of styrene and triethoxysilyl norbornene, copolymer of decyl norbornene and triethoxysilyl norbornene, copolymer of butyl bornene and trimethoxy silyl norbornene, hexyl norbornene and trim Copolymers of alkoxysilyl-norbornene copolymer and the like of decyl norbornene and trimethoxysilyl norbornene are preferred.

In the above formula, R represents an alkyl group having 1 to 10 carbon atoms, and A ¹ and A ² each independently represent a substituent represented by the following chemical formulas 22 to 24. Never. Moreover, p / q + r is 20 or less.

  In the above formula, a represents an integer of 0 to 3, and b represents an integer of 1 to 3.

In the above formula, R ¹ represents a hydrogen atom or a methyl group, and a represents an integer of 0 to 3.

  In the above formula, each X independently represents an alkyl group having 1 to 3 carbon atoms, and a represents an integer of 0 to 3. Examples of the norbornene-based polymer represented by the above chemical formula 19 include any one of butylbornene, hexylnorbornene or decylnorbornene, 2- (5-norbornenyl) methyl acrylate, norbornenylethyltrimethoxysilane, and triethoxysilylnorbornene. Or a terpolymer with either trimethoxysilyl norbornene, butyl bornene, hexyl norbornene or decyl norbornene, terpolymer of 2- (5-norbornenyl) methyl acrylate and methyl glycidyl ether norbornene, butyl bornene, hexyl norbornene or decyl One of norbornene, methyl glycidyl ether norbornene, norbornenyl ethyl trimethoxysilane, triethoxysilyl norborn Terpolymers, etc. with either the emission or trimethoxysilyl norbornene.

In the above formula, R represents an alkyl group having 1 to 10 carbon atoms, R ² represents a hydrogen atom, a methyl group or an ethyl group, Ar represents an aryl group, and X ¹ represents an oxygen atom or a methylene group. X ² represents a carbon atom or a silicon atom, a represents an integer of 0 to 3, c represents an integer of 1 to 3, and p / q is 20 or less. Among the norbornene-based polymers represented by the above chemical formula 23, in particular, R is an alkyl group having 4 to 10 carbon atoms, X ¹ is an oxygen atom, X ² is a silicon atom, Ar is a phenyl group, and R ² is a methyl group. A compound in which a is 1 and c is 2, for example, a copolymer of butylbornene and diphenylmethylnorbornenemethoxysilane, a copolymer of hexylnorbornene and diphenylmethylnorbornenemethoxysilane, a copolymer of decylnorbornene and diphenylmethylnorbornenemethoxysilane, etc. R is an alkyl group having 4 to 10 carbon atoms, X ¹ is a methylene group, X ² is a carbon atom, Ar is a phenyl group, R ² is a hydrogen atom, a is 0, and c is 1, for example, Copolymer of butylbornene and phenylethylnorbornene, hexylnorbornene and fluorine Copolymers of sulfonyl ethyl norbornene copolymer, etc. of decyl norbornene and phenyl ethyl norbornene are preferred. Moreover, although p / q or p / q + r should just be 20 or less, it is preferable that it is 15 or less, and about 0.1-10 is more preferable. Thereby, the effect including the repeating unit of multiple types of norbornene is exhibited.

  The norbornene-based polymer as described above has a relatively low refractive index in addition to the above-described characteristics, and the optical transmission performance of the optical waveguide 240 is configured by forming the clad layer 210 using the norbornene-based polymer as a main material. Can be further improved.

  When the norbornene-based polymer includes a norbornene repeating unit having a substituent containing a (meth) acryl group, the (meth) acryl groups can be crosslinked (polymerized) relatively easily by heating. By mixing a radical generator in the clad film material, the crosslinking reaction between (meth) acrylic groups can be promoted.

  As the radical generator, for example, 2,2-dimethoxy-1,2-diphenylethane-1-one, 1,1-bis (t-butylperoxy) -3,3,5-trimethylcyclohexane and the like are preferably used. .

  In addition, when the norbornene-based polymer includes a norbornene repeating unit having a substituent containing an epoxy group or a norbornene repeating unit having a substituent containing an alkoxysilyl group, in order to directly crosslink these polymerizable groups In the clad film material, the above-mentioned photoacid generator may be mixed and the epoxy group or alkoxysilyl group may be cross-linked by the action of this substance.

  On the other hand, in order to crosslink epoxy groups, (meth) acrylic groups, and alkoxysilyl groups via a cross-linking agent, in the cladding film material, as a cross-linking agent, a polymerizable property corresponding to each polymerizable group. A compound having at least one group may be mixed.

As the crosslinking agent having an epoxy group, for example, 3-glycidoxypropyltrimethoxysilane (γ-GPS), silicone epoxy resin, and the like are preferably used. As a crosslinking agent having a (meth) acryl group, for example, 3-methacryloxypropyltrimethoxysilane tricyclo [5.2.1.0 ^2,6 ] decane dimethanol diacrylate, tripropylene glycol diacrylate and the like are preferable. Used for. As the crosslinking agent having an alkoxysilyl group, for example, a silane coupling agent such as 3-glycidoxypropyltrimethoxysilane or 3-aminopropyltrimethoxysilane is preferably used.

  Further, various additives may be added (mixed) to the clad film material 200. For example, the clad film material 200 may be mixed with the monomers and procatalysts mentioned for the core film material 100. Accordingly, the refractive index of the cladding layer 210 can be changed by reacting the monomer in the cladding layer 210. In particular, when a monomer containing a crosslinkable monomer is used as the monomer, at least a part of the norbornene-based polymer can be crosslinked in the clad layer 210 via the crosslinkable monomer. Further, depending on the type of the crosslinking agent, the type of polymer used for the core layer 110, and the like, the norbornene-based polymer and the polymer used for the core layer 110 can be cross-linked.

  Examples of other additives include the antioxidants described above. By mixing the antioxidant, it is possible to prevent deterioration of the clad film material 200 (norbornene polymer) due to oxidation.

  As the second photoacid generator contained in the clad film material 200, the absorption maximum wavelength (second absorption maximum wavelength) in ultraviolet light is different from the first absorption maximum wavelength of the first photoacid generator. Is used. It is preferable that the second absorption maximum wavelength is longer than the first absorption maximum wavelength. In particular, the first absorption maximum wavelength is less than 300 nm, and the second absorption maximum wavelength is more than 300 nm. preferable.

  Examples of the second photoacid generator include tetrakis (pentafluorophenyl) borate and hexafluoroantimonate, tetrakis (pentafluorophenyl) gallate, aluminates, and antimonates. Other borate salts, gallate salts, carboranes, halocarboranes and the like.

  Examples of such a commercial product of the second photoacid generator include “TAG-382” available from Toyo Ink Manufacturing Co., Ltd., Tokyo, Japan, and Midori Chemical Industries, Ltd., Tokyo, Japan. “NAI-105 (CAS number 85342-62-7)” and the like.

  When TAG-382 is used as the second photoacid generator, a high-pressure mercury lamp or a metal halide lamp is suitably used as the second ultraviolet light irradiation means. Thereby, ultraviolet light with sufficient energy of 300 nm or more can be supplied to the clad film material 200, and TAG-382 can be efficiently decomposed to generate the acid.

  In forming the clad film material 200, a clad varnish containing the polymer, the second photoacid generator, and other required additives is prepared. Examples of the solvent used for preparing the clad varnish include the same solvents as those used for preparing the core varnish. In addition, if necessary, the cladding varnish can increase the sensitivity of the second photoacid generator to the second ultraviolet light and reduce the time and energy required for activation (reaction or decomposition), A sensitizer having a function of changing the wavelength of the second ultraviolet light to a wavelength suitable for the activation may be added. Examples of such a sensitizer include the same sensitizers that are added to the core varnish described above. Furthermore, if necessary, an antioxidant for preventing the generation of undesirable free radicals and natural oxidation of the polymer may be added to the cladding varnish. Examples of such an antioxidant include the same antioxidants as those added to the above-mentioned core varnish.

  The clad varnish has a viscosity (room temperature) of preferably about 100 to 10000 cP, more preferably about 150 to 5000 cP, and still more preferably about 200 to 3500 cP, depending on the coating method described below and the desired film thickness. It can be prepared by adjusting the amount of solvent as appropriate.

  The clad film material 200 can be formed by applying the above-mentioned clad varnish on a support substrate. As the support substrate, for example, a silicon substrate, a silicon dioxide substrate, a glass substrate, a quartz substrate, a polyethylene terephthalate (PET) film, or the like is used. Examples of the coating method include, but are not limited to, a doctor blade method, a spin coating method, a dipping method, a table coating method, a spray method, an applicator method, a curtain coating method, and a die coating method. The thickness of the coating film is not particularly limited, but may be about 5 to 200 μm, preferably about 10 to 100 μm, more preferably about 15 to 65 μm in a state before drying.

  Next, the clad film material 200 can be obtained by removing the solvent in the coating film (desolvation), that is, by drying. Examples of the solvent removal (drying) method include heating, leaving under atmospheric pressure or reduced pressure, and spraying (blowing) an inert gas. For example, a method using heating using a hot plate Is preferred. This makes it possible to remove the solvent relatively easily and in a short time. When heating, it is preferable that heating temperature is about 25-60 degreeC, and it is more preferable that it is about 30-45 degreeC. Further, the heating time is preferably about 15 to 60 minutes, more preferably about 15 to 30 minutes.

  The obtained clad film material 200 is peeled from the support substrate, and then brought into contact with one side or both sides of the core layer 110 and thermally bonded to each other. For thermocompression bonding, for example, a laminator can be conveniently used. According to the post-irradiation method, since the clad film material 200 to be thermocompression-bonded is in a low Tg state not irradiated with ultraviolet light, the thermocompression bonding process is performed at a low temperature and low pressure so that the hollow mirror structure provided in the core portion is not crushed. Can be implemented. The temperature for thermocompression bonding is generally set in the range of 80 to 130 ° C, preferably 100 to 120 ° C. The pressure for thermocompression bonding is generally 0.1 to 10 MPa, preferably 0.1 to 4 MPa. Note that no acid is released from the second photoacid generator contained in the clad film material 200 during thermocompression bonding.

  In the above-described thermocompression bonding process, a gas atmosphere such as air that can be entrained and remain between the clad film material 200 and the core layer 110 at the time of lamination is minimized by applying a reduced pressure atmosphere or a vacuum as necessary. It is preferable to suppress the occurrence of voids at the contact portion in order to obtain a laminate 230 with good flatness. In this case, the inside of the hollow mirror structure is also reduced-pressure air or vacuum, but there is no problem as long as the hollow mirror structure is not deformed, such as depression of the cladding layer. The reduced-pressure atmosphere or vacuum can be applied when the clad film material 200 and the core layer 110 are in contact, or when the clad film material 200 and the core layer 110 are thermocompression bonded, or both. A reduced-pressure atmosphere or a vacuum can be applied by employing a vacuum lamination, a vacuum press, or the like.

  Next, the entire surface of the laminate 230 is irradiated with a second ultraviolet light having a wavelength that includes the second absorption maximum wavelength but does not include the first absorption maximum wavelength, using the wavelength cut filter 220, for example. The film material 200 is converted into the clad layer 210 and the adhesion between the core layer 110 and the clad layer 210 is improved. For example, when the first absorption maximum wavelength is less than 300 nm and the second absorption maximum wavelength is 300 nm or more, the entire surface of the stacked body 230 can be irradiated with second ultraviolet light having a wavelength of 300 nm or more. By the entire irradiation of the second ultraviolet light, acid is released from the second photoacid generator contained in the clad film material 200. On the other hand, since the first photoacid generator contained in the core layer 110 is substantially insensitive to the second ultraviolet light, the refractive index of the core portion 101 does not change or decrease (clad). The acid released from the second photoacid generator catalyzes the crosslinking reaction via the polymerizable group of the constituent polymer of the clad film material 200. For example, when the constituent polymer contains an epoxy group, the cationic polymerization of the epoxy is initiated by the acid released from the second photoacid generator, and a crosslinked structure is formed inside the clad film material 200. Strength is improved. In addition, when the constituent polymer of the adjacent core layer 110 includes a polymerizable group (eg, epoxy group) that can participate in the cross-linking reaction, the cationic polymerization extends to the core layer 110 and the cladding layer 210 and the core layer 110. A cross-linked structure is formed between them and the adhesion between them is improved.

Irradiation of the second ultraviolet light is preferably in the range of about 10~1000J / cm ^2, more preferably about 10~500J / cm ^2, even more preferably about 10~300J / cm ² . Thereby, a 2nd photo-acid generator can be activated reliably.

  Thereafter, if necessary, the laminated body 230 is subjected to a heat treatment to complete the crosslinking reaction of the clad layer 210. In this heat treatment, a plurality of laminated bodies 230 can be simultaneously processed by batch processing (oven heating) without applying pressure, so that the productivity of the optical waveguide 240 is improved. Although heating temperature is not specifically limited, It is preferable that it is about 100-180 degreeC, and it is more preferable that it is about 120-150 degreeC. The heating time is set so as to sufficiently stop the crosslinking (curing) reaction, and is not particularly limited, but is preferably about 30 to 120 minutes, and more preferably about 45 to 90 minutes.

  FIG. 16 shows an optical waveguide module 350 including the above-described optical waveguide and a light emitting element and / or a light receiving element. As shown in FIG. 16, the optical waveguide module 350 according to the present invention includes an optical waveguide including an upper cladding layer 351, a core portion 352, a lower cladding layer 353, and a hollow mirror structure 354, and a support member 357 on the optical waveguide. And a light emitting element and / or a light receiving element 355 mounted thereon. By the mirror surface of the hollow mirror structure according to the present invention, light that passes through the upper cladding layer 351 from the light emitting portion 356 of the light emitting element 355 and enters the core portion 352 of the optical waveguide, or from the core portion 352 of the optical waveguide to the upper cladding layer. The optical path LP of the light that passes through 351 and is emitted to the light receiving unit 356 of the light receiving element 355 is converted into a substantially vertical direction. For light-emitting elements and / or light-receiving elements in such an optical waveguide module, refer to JP-A-2005-321560, JP-A-2004-193610, and JP-A-9-148621.

  FIG. 17 shows an optical element mounting board 360 including the above-described optical waveguide module and an electric circuit board. As shown in FIG. 17, the optical element mounting board 360 according to the present invention includes an optical waveguide module A and an electric circuit board B. As shown in FIG. 17, the optical waveguide module A includes an optical waveguide including an upper cladding layer 361, a core portion 362, a lower cladding layer 363, and a hollow mirror structure 364, and a metal protrusion 367 and an electrode pad on the optical waveguide. A light emitting element and / or a light receiving element 365 mounted via 368. The conductor circuit 369 formed on the electric circuit board B is electrically connected to the light emitting element and / or the light receiving element 365 via the metal protrusion 367 and the electrode pad 368 (not shown). As an operation of the optical element mounting substrate 360, for example, when the conductor circuit 369 outputs an electrical signal to the light emitting element 365, the light emitting element 365 converts the electrical signal into an optical signal and emits the optical signal from the light emitting unit 366. . The emitted optical signal passes through the upper clad layer 361, the optical path LP is converted into a substantially vertical direction by the mirror surface of the hollow mirror structure 364, and enters the core portion 362 of the optical waveguide. Thereafter, the incident optical signal propagates in the core part 362, the optical path LP is converted into a substantially vertical direction by the mirror surface of another hollow mirror structure 364 (not shown), passes through the upper cladding layer 361, The light enters the light receiving portion 366 of the light receiving element 365. The optical signal incident on the light receiving element 365 is converted into an electrical signal and input to another conductor circuit 369 (not shown). In this way, an optical signal is transmitted at high speed between the two conductor circuits. For details of such an optical element mounting substrate, refer to, for example, Japanese Patent Laid-Open No. 2000-199827.

  18A to 18C, in the above-described optical element mounting substrate, the optical waveguide module provides electrical conduction between the electrode of the light emitting element and / or the light receiving element and the electrode of the electric circuit board. One having a receptor structure 370 is shown. By providing such a receptor structure, mounting accuracy is high, light propagation loss is reduced, and further, the distance between the light receiving and emitting part of the optical element and the core part of the optical waveguide is shortened, so that the light propagation efficiency This contributes to reducing the thickness of the optical element mounting substrate. 18A, the optical waveguide module includes an optical waveguide including an upper cladding layer 371, a core portion 372, a lower cladding layer 373, and a hollow mirror structure 374, and a metal protrusion 377 on the optical waveguide. A light emitting element and / or a light receiving element 375 mounted thereon. In the optical waveguide, a receptor structure (through hole) having a size sufficient to receive the metal protrusion 377 is formed. The conductor circuit 379 formed on the electric circuit board is electrically connected to the light emitting element and / or the light receiving element 375 via a metal protrusion 377 received in the receptor structure. In the embodiment shown in FIG. 18A, the optical waveguide module and the electric circuit board are joined by the conductive adhesive 378. The mode shown in FIG. 18 (B) is different from the mode shown in FIG. 18 (A) in that a conductor post 380 is partially provided in the receptor structure to ensure the height of the conductor. Furthermore, the mode shown in FIG. 18C is that the conductor post 380 is formed on the entire receptor structure portion, and the light emitting element and / or the light receiving element 375 does not have a metal protrusion. It is different from the embodiment shown in FIG. The basic operation of the optical element mounting substrate 370 shown in FIGS. 18A to 18C is the same as the operation of the optical element mounting substrate 360 described above with reference to FIG. The details of the optical device mounting board having such a receptor structure are described in Japanese Patent Application No. 2006-149743 (filed on May 30, 2006, entitled “Optical Device Mounting Board, Optical Circuit Board” filed by the present applicant). And the optical element mounting substrate ”).

Hereinafter, an example for explaining the present invention more concretely is provided.
Example 1
1. Preparation of core layer having hollow mirror structure <Synthesis of hexyl norbornene (HxNB) / diphenylmethylnorbornene methoxysilane (diPhNB) copolymer>
HxNB (CAS number 22094-83-3) (9.63 g, 0.054 mol), diPhNB (CAS number 376634-34-3) (40.37 g, 0.126 mol), 1-hexene ( 4.54 g, 0.054 mol) and toluene (150 g) were mixed in a 500 mL sealam bottle in a dry box, and further stirred while heating to 80 ° C. in an oil bath to obtain a solution. To this solution was added Pd1446 (1.04 × 10 ⁻² g, 7.20 × 10 ⁻⁶ mol) and N, N-dimethylanilinium tetrakis (pentafluorophenyl) borate (DANFABA) (2.30 × 10 ⁻² ). g, 2.88 × 10 ⁻⁵ mol) was added in the form of a concentrated dichloromethane solution (0.1 mL), respectively. The mixture after addition was stirred with a magnetic stirrer at 80 ° C. for 2 hours. Thereafter, the reaction mixture (toluene solution) was transferred to a larger beaker and methanol (1 L), which is a poor solvent, was added dropwise thereto to precipitate a fibrous white solid. The solid content was collected by filtration and vacuum dried in an oven at 60 ° C. to obtain a product having a dry mass of 19.0 g (yield 38%). When the molecular weight of the product was measured by gel permeation chromatography (GPC: THF solvent, polystyrene conversion), the mass average molecular weight (Mw) was 118,000 and the number average molecular weight (Mn) was 60,000. The product was measured by ¹ H-NMR and identified as a HxNB / diPhNB-based copolymer (x = 0.32, y = 0.68, n = 5) represented by the following structural formula. When the refractive index of this copolymer was measured by the prism coupling method, the TE mode was 1.5695 and the TM mode was 1.5681 at a wavelength of 633 nm.

<Preparation of core varnish>
Under yellow light, the HxNB / diPhNB copolymer was dissolved in mesitylene to prepare a 10 wt% copolymer solution (30 g). Separately, in a 100 mL glass bottle, HxNB (42.03 g, 0.24 mol) and bis-norbornenemethoxydimethylsilane (SiX, CAS No. 376609-87-9) (7.97 g, 0.026 mol) ) Were added, and two types of antioxidants [Irganox 1076 (0.5 g) and Irgafos 168 (0.125 g) manufactured by Ciba) were added to obtain a monomer antioxidant solution. To 30.0 g of the above copolymer solution, 3.0 g of the above monomer antioxidant solution and Pd (PCy ₃ ) ₂ (OAc) ₂ (Pd785) (4.95 × 10 ⁻⁴ g, 6.29 × 10 ^{− 7} mol in 0.1 mL of methylene chloride) and a first photoacid generator [RHODORSIL (registered trademark) PHOTOINITIATOR 2074 (CAS No. 178233-72-2)] (2.55 × 10 ^{− 3} g, 2.51 × 10 ⁻⁶ mol, in 0.1 mL of methylene chloride) was added and dissolved uniformly, and then filtered through a filter having a pore diameter of 0.2 μm to prepare a core varnish.

<Preparation of core layer (single-layer optical waveguide element film)>
On a polyethylene terephthalate (PET) film having a thickness of 250 μm, 10 g of the core varnish was poured, and the core varnish was spread with a doctor blade to form a coating film (before drying). Thickness of 70 μm). This coating film was placed on a hot plate together with a PET film and heated at 50 ° C. for 45 minutes to evaporate toluene, thereby obtaining a dry coating film having a thickness of 50 μm. This dried coating film was irradiated with a first ultraviolet light having a wavelength of less than 300 nm or less than 365 nm using a high-pressure mercury lamp or a metal halide lamp through a photomask having a predetermined opening pattern corresponding to the cladding portion (irradiation amount: 500 mJ / cm ² ). The film after irradiation was placed in an oven, and was first subjected to heat treatment at 50 ° C. for 30 minutes, then at 85 ° C. for 30 minutes, and then at 150 ° C. for 60 minutes. At the time of heating for 10 minutes at the first 50 ° C., the waveguide pattern in the coating film could be visually confirmed. After the heat treatment, the coating film was peeled from the PET film to form a core layer (single-layer optical waveguide element film).

<Excimer laser adjustment>
Prior to forming the hollow mirror structure as shown in FIG. 3 on the core layer, an excimer laser device (ATLEX-300SI, manufactured by ATL LaserTechnik) was adjusted as follows. After exhausting the pressure in the chamber provided in the excimer laser device to 10 mbar or less, ArF premixed gas (Ar: 4.13%, F ₂ : 0.17%, neon gas: The remainder) was filled to 6500 mbar. In the excimer laser device, the laser light is condensed through a lens, and then further projected through a stainless steel mask in which a 1000 × 1000 μm square hole is processed, so that the final irradiation area is substantially 100 ×. It adjusted so that it might be set to 100 micrometers. When an excimer laser was oscillated at a frequency of 100 Hz and the output of the laser beam finally reaching the processing surface (through the mask) was measured with a power meter (PE50-DIF-U, manufactured by OPHIR Japan), 3. It was 5 mW.

<Mirror processing>
The surface opposite to the mirror processed surface of the core layer (single-layer optical waveguide element film) (thickness 50 μm, core width 50 μm) is pasted on an adhesive substrate (Magic Resin: manufactured by Toyo Corporation) I attached. The base was placed on a fine movement stage of an excimer laser device, and the fixed surface of the base was sucked and fixed. Next, after adjusting the alignment by rotating the stage so that the longitudinal direction of the core portion of the three-layer waveguide coincides with the movable direction of the fine movement stage, the center of the laser irradiation area (100 × 100 μm) is the center of the core portion. It was adjusted to come to. Next, while flowing He gas as an assist gas at a flow rate of 2.0 L / min to the mirror processing part of the core part, the fine movement stage was moved 150 μm at 16 μm / second in the optical path direction, and a laser with a frequency of 100 Hz was irradiated in the meantime. After the irradiation, the core layer was cut along the core portion and the cross section was observed. As a result, an inclination of 45 degrees with respect to the plane defined by the core layer was formed. Further, when the inclined surface (mirror surface) was observed with a scanning electron microscope (SEM), almost no smear (carbonized laser ablation) deposited on the mirror surface was observed, and the mirror surface was very smooth. It was.

2. Preparation of Cladding Film Material <Synthesis of Decyl Norbornene (DeNB) / Methyl Glycidyl Ether Norbornene (AGENB) Copolymer>
DeNB (CAS number 22094-85-5) (16.4 g, 0.07 mol), AGENB (CAS number 3188-75-8) (5.41 g, 0.03 mol) and toluene (58. 0 g) was placed in a 500 mL sealam bottle in a dry box and mixed, and further stirred while heating to 80 ° C. in an oil bath to obtain a solution. To this solution was added a toluene solution (5 g) of (η ⁶ -toluene) Ni (C ₆ F ₅ ) ₂ (0.69 g, 0.0014 mol). The mixture after addition was stirred with a magnetic stirrer at room temperature for 4 hours. To the mixture was added toluene (87.0 g) and stirred vigorously. Thereafter, the reaction mixture (toluene solution) was transferred to a larger beaker and methanol (1 L), which is a poor solvent, was added dropwise thereto to precipitate a fibrous white solid. The solid content was collected by filtration and vacuum dried in an oven at 60 ° C. to obtain a product having a dry mass of 17.00 g (yield 87%). When the molecular weight of the product was measured by GPC (THF solvent, polystyrene conversion), Mw = 75,000 and Mn = 30,000. The product was measured by ¹ H-NMR and identified as a DeNB / AGENB copolymer (x = 0.77, y = 0.23, n = 10) represented by the following structural formula. When the refractive index of the copolymer was measured by the prism coupling method, the TE mode was 1.5153 and the TM mode was 1.5151 at a wavelength of 633 nm.

<Preparation of clad varnish>
Under yellow light, 10 g of the copolymer was dissolved in dehydrated toluene to prepare a 20 wt% copolymer solution (50 g). To this solution, two types of antioxidants [Irganox 1076 (0.01 g) and Irgafos 168 (0.0025 g) manufactured by Ciba) and a second photoacid generator (TAG-382 manufactured by Toyo Ink Co., Ltd.) having an absorption maximum wavelength of 335 nm. 0.2 g), and uniformly dissolved, followed by filtration with a filter having a pore size of 0.2 μm to prepare a cladding varnish.

<Production of clad film material>
10 g of clad varnish was poured onto a PET film having a thickness of 100 μm arranged on a horizontal base, and spread with a doctor blade so as to have a substantially constant thickness to form a coating film of clad varnish (dried) Previous thickness 30 μm). This coating film was put into a dryer together with a PET film and heated at 50 ° C. for 15 minutes to evaporate toluene to obtain a dried coating film having a thickness of 20 μm. Thereafter, the dried coating film was peeled from the PET film to obtain a clad film material.

3.3 Batch Manufacturing of Three-Layer Optical Waveguide The clad film material (size 25 × 25 cm) was laminated one by one on each surface of the core layer (size 20 × 20 cm) having a hollow mirror structure. This three-layer laminate was put into a laminator set at 120 ° C. and thermocompression bonded under a pressure of 0.2 MPa for 5 minutes. Thereafter, the three-layer laminate was returned to room temperature and normal pressure, and a PET film having a thickness of 100 μm was disposed between this and the high-pressure mercury lamp as a wavelength cut filter that shields wavelengths of 300 nm or less. Next, second ultraviolet light was irradiated from a high-pressure mercury lamp through a wavelength cut filter (irradiation amount: 100 mJ / cm ² ). The three-layer laminate after irradiation is immediately put into a drier without leaving it to stand (stand time 0 minutes) and heated at 150 ° C. for 30 minutes to cure the clad film material (cladding layer) and core layer / cladding The adhesion strength between layers was completed. Thereafter, a double-sided tape was inserted between the copper layer (conductor layer) having an average thickness of 45 μm and the three-layer laminate, and both were joined by roll lamination, and the following evaluation was performed.

4). Evaluation <Propagation loss>
Regarding the propagation loss of the obtained three-layer optical waveguide, the light generated from the laser diode is input from one end of the core portion through the optical fiber, the output from the other end is measured, and the length of the core portion is several steps long. It measured by the cut-back method which measured the light output about each length. The total optical loss in each length of the core part is expressed by the following formula.
Total optical loss (dB) =-10 log (Pn / P0)
Where Pn is the measured output at the other end of each of the cores of length P1, P2,... Pn, and P0 is the end of the optical fiber before coupling the optical fiber to one end of the core. It is the measurement output of the light source in.
Next, the total optical loss is plotted as in FIG. The regression line of this data is expressed by the following equation.
y = mx + b
In the above equation, m represents a light propagation loss, and b represents a coupling loss. The propagation loss of the optical waveguide of Example 1 was 0.06 dB / cm.

<Mirror loss>
About the loss of the mirror part of the obtained three-layer optical waveguide, the light generated from the laser diode or the surface emitting laser (VCSEL) is input from one end of the core part through the optical fiber, reflected by the mirror inclined part, and clad layer The output of the light that passed through was measured, and the total light loss represented by the following formula was obtained.
Total optical loss (dB) =-10 log (P1 / P0)
In the above equation, P1 is the output measured at the upper part of the inclined portion, and P0 is the measured output of the light source at the end of the optical fiber before coupling the optical fiber to one end of the core. The loss at the mirror portion was calculated by subtracting the loss at the straight line portion and the loss at the coupling portion between the optical fiber and the core portion from the total optical loss obtained. The loss of the mirror part of the optical waveguide of Example 1 was 0.5 dB / cm.

<Smoothness of mirror part>
About the smoothness of the mirror part of the obtained three-layer optical waveguide, a confocal laser microscope (LXET OLS-3100 manufactured by Olympus) was used so that the mirror surface of the three-layer optical waveguide was almost horizontal. The maximum height of the protrusion was measured directly. The smoothness of the mirror part of the optical waveguide of Example 1 was less than 100 nm.

<Tensile strength>
When the obtained three-layer optical waveguide was cut into the shape of the test piece specified by JIS K7127, the mirror part was arranged at the narrowest parallel part corresponding to the center of the test piece. The both ends of this test piece are sandwiched between chuck portions of a tensile tester (tensile tester Tensilon STM-T-50 manufactured by A & D Co., Ltd.) and the crosshead speed is maintained at 5 cm / min. It was actuated and the strength at which the test piece broke was measured. The tensile strength of the optical waveguide of Example 1 was 500 gf / cm or more.

<Smear generation amount>
When forming the mirror part (hollow mirror structure) of the three-layer optical waveguide, the generation amount (attachment area) of fine carbonized dust (smear) that was ablated by the excimer laser and adhered to the mirror part was visually observed. . In the optical waveguide of Example 1, almost no smear was observed.

Comparative Example 1
A three-layer optical waveguide was manufactured in the same manner as in Example 1 except that the core layer (single-layer optical waveguide element film) was not subjected to mirror processing. Next, mirror processing was applied to the three-layer optical waveguide as follows using an excimer laser adjusted in the same manner as in Example 1.

  The base film (PES) on one side of the three-layer optical waveguide was peeled off, and the surface opposite to the mirror processed surface was pasted on an adhesive base (Magic Resin: manufactured by Toyo Corporation). . The base was placed on a fine movement stage of an excimer laser device, and the fixed surface of the base was sucked and fixed. Next, after adjusting the alignment by rotating the stage so that the longitudinal direction of the core portion of the three-layer waveguide coincides with the movable direction of the fine movement stage, the center of the laser irradiation area (100 × 100 μm) is the center of the core portion. It was adjusted to come to. Next, while flowing He gas as an assist gas at a flow rate of 2.0 L / min to the mirror processing part of the core part, the fine movement stage was moved 150 μm at 16 μm / second in the optical path direction, and a laser with a frequency of 100 Hz was irradiated in the meantime. After irradiation, the three-layer optical waveguide was cut along the core portion, and the cross section was observed. As a result, a 45-degree inclination was formed from the lower cladding layer to the core layer with respect to the plane defined by the three-layer optical waveguide. It was. Further, when the inclined surface (mirror surface) was observed with a scanning electron microscope (SEM), the adhesion area of smear (carbonized laser ablated material) deposited on the mirror surface was larger than in Example 1, but the mirror The surface was smooth.

  In the same manner as in Example 1, propagation loss, mirror loss, smoothness of the mirror part, tensile strength, and amount of smear were measured. These measurement results are shown in Table 1 together with the measurement results of Example 1.

  As can be seen from Table 1, there is no significant difference between Example 1 and Comparative Example 1 in terms of mirror performance (propagation loss, mirror loss, smoothness). On the other hand, with respect to the tensile strength that represents the mechanical strength of the optical waveguide, Example 1 showed a value that is 10 times or more that of Comparative Example 1. In addition, regarding the amount of smear generated, Comparative Example 1 was greater than Example 1. This is because in Comparative Example 1, not only the core layer but also the cladding layer must be ablated compared to Example 1 in which only the core layer needs to be ablated. Since the size of each smear particle is 100 nm or less, it does not affect the smoothness itself. However, if the amount of smear generated increases, the smear particles aggregate and damage the mirror surface, resulting in mirror loss. May worsen. In addition, since the mirror surface of Example 1 is sealed with the clad layer as a matter of course, the contamination caused by the adhesion of dust and dust from the outside compared to the mirror surface of Comparative Example 1 exposed to the ambient atmosphere. Hard to wear. Further, as a merit at the time of mirror processing, the comparative example 1 requires a relatively large mask (more than twice the core width) in order to ablate the upper clad layer with a constant taper angle. Since only the core layer has to be ablated, a relatively small mask (more than 1.5 times the core width) can be used.

Example 2
<Cross-waveguide type having an anti-interference clad structure> In the same manner as in Example 1, except that <production of core layer (single-layer optical waveguide element film)> and <mirror processing> were changed as follows. A three-layer optical waveguide was manufactured.

<Fabrication of crossed waveguide core layer with anti-interference clad structure>
On a polyethylene terephthalate (PET) film having a thickness of 250 μm, 10 g of the core varnish was poured and spread with a doctor blade so as to have a substantially constant thickness to form a coating film of the core varnish (before drying). Thickness of 70 μm). This coating film was placed on a hot plate together with a PET film and heated at 50 ° C. for 45 minutes to evaporate toluene, thereby obtaining a dry coating film having a thickness of 50 μm. A predetermined closed pattern corresponding to the core portion as shown in FIG. 12A (core width 50 μm: number of cores / vertical 12; horizontal 12: core pitch / vertical 125 μm; horizontal 125 μm: orthogonal) And a first ultraviolet having a wavelength of less than 300 nm or less than 365 nm using a high-pressure mercury lamp or metal halide lamp through a photomask having a predetermined opening pattern (low refractive area width 5 μm) corresponding to the cladding portion and the low refractive area. Light was irradiated (irradiation amount: 500 mJ / cm ² ). The film after irradiation was placed in an oven, and was first subjected to heat treatment at 50 ° C. for 30 minutes, then at 85 ° C. for 30 minutes, and then at 150 ° C. for 60 minutes. At the time of heating for 10 minutes at the first 50 ° C., the waveguide pattern in the coating film could be visually confirmed. After the heat treatment, the coating film was peeled from the PET film to obtain a crossed waveguide core layer having a crosstalk prevention clad structure.

<Mirror processing>
The surface of the core layer (crossed waveguide core layer having an anti-interference clad structure) (thickness 50 μm, core width 50 μm) opposite to the mirror-processed surface is an adhesive substrate (Magic Resin: Toyo Corporation) Pasted on the company). The base was placed on a fine movement stage of an excimer laser device, and the fixed surface of the base was sucked and fixed. Next, after adjusting the alignment by rotating the stage so that the longitudinal direction of the core portion of the three-layer waveguide matches the movable direction of the fine movement stage, the center of the laser irradiation area (10 × 70 μm) intersects the core portion. Adjusted to be in the center of the area. Next, while flowing He gas as an assist gas at a flow rate of 2.0 L / min to the mirror processing portion of the core part, the fine movement stage is moved 70 μm at 5 μm / second on the diagonal line of the intersecting region of the core part, and at a frequency of 100 Hz The laser was irradiated. After irradiation, the cut surface was observed with a scanning electron microscope (SEM). As a result, almost no smear (carbonized laser ablation product) deposited on the cut surface was observed, and the cut surface was very smooth.

  In the same manner as in Example 1, the propagation loss, the mirror loss, the smoothness of the mirror part, the tensile strength, and the amount of smear generated were measured. As a result, the crossed waveguide type three-layer optical waveguide having the crosstalk prevention clad structure of Example 2 was measured. In all the characteristics, the same characteristics as those of the optical waveguide of Example 1 were exhibited.

It is a fragmentary perspective view which shows typically the basic structure of an optical waveguide. It is a cross-sectional view which shows typically an example of the conventional structure which demarcates the mirror surface in an optical waveguide. It is a cross-sectional view which shows typically an example of the hollow mirror structure body by this invention which demarcates the mirror surface in an optical waveguide. It is a cross-sectional view which shows typically the hollow mirror structure by another aspect by this invention. 1 is a plan view schematically showing an optical waveguide in which a plurality of core portions according to the present invention are arranged. It is a top view which shows typically the optical waveguide which the core part by this invention branched. It is a top view which shows typically the optical waveguide by which the optical path direction by this invention is converted into a substantially right angle in a plane. It is a top view which shows typically the crossing type | mold waveguide which comprised the hollow mirror structure by this invention. It is a top view which shows typically the various branch aspects of the optical path by this invention. It is a fragmentary perspective view which shows typically the multilayered crossing type | mold waveguide which comprised the hollow mirror structure by this invention. It is a top view which shows typically an example of the crossing type | mold waveguide which has an interference prevention clad structure. It is the top view (A) and cross section (B) which show typically a part of process example of the method suitable for manufacture of an interference prevention clad structure. It is a top view which shows typically a part of process of the method suitable for providing the hollow mirror structure body by this invention in the cross | intersection area | region of a cross-type waveguide. It is a cross-sectional view which shows typically a part of process example of the method (post irradiation method) suitable for manufacture of the optical waveguide by this invention. It is a cross-sectional view which shows typically a part of process example of the method (post irradiation method) suitable for manufacture of the optical waveguide by this invention. It is a cross-sectional view which shows typically an example of the optical waveguide module optical waveguide containing the optical waveguide by this invention, and a light emitting element and / or a light receiving element. It is a cross-sectional view which shows typically an example of the optical element mounting board | substrate containing the optical waveguide module and electric circuit board | substrate by this invention. It is a cross-sectional view which shows typically an example of the optical element mounting substrate by this invention which has a receptor structure. It is a chart which shows the change of the total optical loss accompanying the change of the length of a core part.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Optical waveguide 2 Core part 3 Upper clad layer 3 'Clad part 4 Lower clad layer 10 Optical waveguide 11 Upper clad layer 12 Core part 13 Lower clad layer 14 Mirror structure LP Optical path 20 Optical waveguide 21 Upper clad layer 22 Core part 23 Lower part Cladding layer 24 Hollow mirror structure 31, 41, 51 Upper cladding layer 32, 42, 52 Core part 33, 43, 53 Lower cladding layer 34, 44, 54 Hollow mirror structure 62, 72 Core part 64, 74 Hollow mirror structure Body 82 Core part 84 Hollow mirror structure 90 Optical waveguide 91, 91 ′ Mask closing part 92 Core part 92 ′ Crossing region 93 Upper cladding layer 94 Hollow mirror structure 95 Interlayer cladding 96 Cladding part 97 Lower cladding layer 98 Laser irradiation part 100 Core film material 101 Core portion 102 Clad Part 110 Core layer 120 Photomask 200 Clad film material 210 Clad layer 220 Wavelength cut filter 230 Laminate 240 Optical waveguide 350 Optical waveguide module 351 Upper clad layer 352 Core part 353 Lower clad layer 354 Hollow mirror structure 355 Light emitting element and / or Light receiving element 356 Light receiving / emitting part 357 Support member 360 Optical element mounting substrate 361 Upper cladding layer 362 Core part 363 Lower cladding layer 364 Hollow mirror structure 365 Light emitting element and / or light receiving element 366 Light receiving / emitting part 367 Metal projection 368 Electrode pad 369 Conductor circuit A Optical waveguide module B Electrical circuit board 370 Optical device mounting board provided with receptor structure 371 Upper cladding layer 372 Core part 373 Lower cladding layer 374 Hollow mirror Structure 375 Light emitting element and / or light receiving element 377 Metal protrusion 378 Conductive adhesive 379 Conductor circuit 380 Conductor post

Claims (20)

  An optical waveguide formed by surrounding a core portion defining an optical path direction with a cladding layer having a refractive index lower than that of the core portion, and light incident on the optical waveguide at a predetermined position along the optical path direction of the core portion An optical waveguide comprising a hollow mirror structure that defines a mirror surface for converting an optical path of light emitted from the optical waveguide.   The optical waveguide according to claim 1, wherein a height of the hollow mirror structure is equal to or greater than a thickness of the core portion.   The optical waveguide according to claim 1, wherein an additional hollow mirror structure is provided at a position different from the predetermined position in the same optical path including the predetermined position where the hollow mirror structure is provided.   The optical waveguide according to any one of claims 1 to 3, wherein a mirror surface of the hollow mirror structure forms an angle of 40 to 50 degrees with respect to the optical path direction.   The optical waveguide according to any one of claims 1 to 4, wherein the optical path direction is converted by the mirror surface into a substantially normal direction with respect to a plane defined by the optical waveguide.   The optical waveguide is an optical waveguide in which a plurality of core parts are arranged at a narrow interval at a narrow interval, and the hollow mirror structures are juxtaposed independently for each core part. The optical waveguide according to any one of the above.   The optical waveguide is an optical waveguide in which a plurality of core portions are arranged at a narrow interval at a narrow interval, and a common hollow mirror structure is provided in which the hollow mirror structure extends over two or more of the core portions. The optical waveguide according to any one of claims 1 to 5.   6. The optical waveguide according to claim 1, wherein the optical waveguide is a branched optical waveguide with a core portion branched, and a hollow mirror structure is installed at an arbitrary position of each branched core portion. Optical waveguide.   The optical waveguide according to claim 1, wherein the optical path direction is converted by the mirror surface in a plane defined by the optical waveguide.   10. The optical waveguide according to claim 9, wherein the optical waveguide is an intersecting waveguide in which a plurality of core portions intersect, and the hollow mirror structure is installed in at least one of the intersecting regions of the core portion. Optical waveguide.   The optical waveguide according to claim 10, wherein the hollow mirror structure is installed so as to branch one optical path in two directions at the intersection region.   The optical waveguide according to claim 10, wherein the hollow mirror structure is installed so as to branch one optical path in three directions in the intersecting region.   A hollow mirror structure in which the intersecting waveguide is a multi-layered intersecting waveguide in which the core portion is overlapped two or more above and below via a clad, and the upper and lower core portions are optically connected The optical waveguide according to claim 10, wherein the body is installed at a predetermined position.   The optical waveguide according to any one of claims 10 to 13, wherein the intersecting waveguide has an anti-interference clad structure in which a low refraction region having a refractive index lower than that of the core portion is provided on an outer peripheral portion of the intersecting region. Waveguide.   The optical waveguide includes a core layer including a core portion that defines an optical path direction, a cladding portion having a lower refractive index than the core portion, and a cladding layer laminated on both surfaces of the core layer. The optical waveguide according to claim 1.   The optical waveguide according to claim 15, wherein the core layer and the clad layer are made of a polymer material.   The optical waveguide according to claim 16, wherein the polymer material includes a main chain mainly composed of addition polymerization type norbornene.   An optical waveguide module comprising the optical waveguide according to any one of claims 1 to 8 and 15 to 17, and a light emitting element and / or a light receiving element, wherein the hollow mirror structure and the light emitting element and / or light receiving The light emitted from the light emitting element enters the optical waveguide via the mirror surface of the hollow mirror structure and / or the light emitted from the optical waveguide passes through the mirror surface of the hollow mirror structure. An optical waveguide module, wherein the optical waveguide module is aligned so as to enter the light receiving element.   An optical element mounting board comprising the optical waveguide module according to claim 18 and an electric circuit board.   20. The optical element mounting substrate according to claim 19, wherein the optical waveguide module has a receptor structure for providing electrical conduction between an electrode of the light emitting element and / or a light receiving element and an electrode of the electric circuit board.

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