JP2006184801A - Optical waveguide and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical waveguide and its manufacturing method with which lead time to a production phase is reduced and the cost is also reduced by eliminating the design and the production in accordance with an individual case during mounting operations. <P>SOLUTION: The optical waveguide includes a clad layer and a core layer and signal light beams are made incident, propagated and emitted via the core layer. At least a portion of the core layer is formed of a plurality of layers. The manufacturing method is for the optical waveguide, in which the clad layer is made of a bottom clad layer 2A, an intermediate clad layer 2B and a top clad layer 2C. The manufacturing method includes a step in which a mold is pressed onto the coated bottom clad layer to form a groove section and a first core layer 1A is coated in the groove section, a step in which a step is repeated equal to once or more to form a second core layer in the coated intermediate clad layer on the bottom clad layer, to form a second core layer having at least one layer, and a step in that the top section clad layer is coated on the intermediate clad layer being formed on which the second core layer is formed. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an optical waveguide and a method for manufacturing the same. More specifically, the present invention is used with a wiring board, in particular, an electric / optical mixed wiring board configured by using both electric wiring and optical wiring together with an electric wiring portion. The present invention relates to an optical waveguide and a method for manufacturing the same.

  2. Description of the Related Art In recent years, an optical wiring technique has been introduced in an electric wiring board in an electronic device for the purpose of improving a signal transmission speed. Specifically, an optical waveguide is applied as an optical wiring in the wiring board, and is used by being laminated with an electric wiring layer. Such a wiring board configured by mixing electrical wiring and optical wiring is generally called an electrical / optical mixed wiring board.

Various studies have so far been made on such an electric / optical mixed wiring board. For example, Patent Document 1 discloses that high-density mounting or miniaturization is possible, and that mounting of optical components is mounting of electrical components. For the purpose of realizing an optical / electrical wiring board that can be performed by the same method, an optical / electrical wiring board in which an electric wiring board in which electric wiring is embedded and an optical substrate in which an optical waveguide is embedded is laminated, A technique for penetrating through a columnar conductive guide formed on an electric wiring board is described. Further, Patent Documents 2, 3 and the like also disclose improved techniques related to the electric / optical mixed wiring board.
JP 2000-340906 A (Claims etc.) JP 2003-287737 A (Claims etc.) JP 2004-163722 A (Claims etc.)

  Conventionally, optical waveguides used in the above-mentioned mixed electrical / optical wiring board have been commercialized by designing a core pattern such as a straight line or a Y-shaped branch in advance. Therefore, when using the actual wiring board for mounting light-emitting elements, light-receiving elements, etc., the mounting position, mounting direction, number of mounted elements, etc. vary widely. Therefore, there is a problem in that it is disadvantageous in terms of lead time to commercialization and cost.

  Accordingly, an object of the present invention is to solve the above problems and eliminate the need for designing and manufacturing according to individual cases at the time of mounting, thereby shortening the lead time to commercialization and reducing the cost. An object of the present invention is to provide an optical waveguide that can be manufactured and a method of manufacturing the same.

  As a result of intensive studies, the present inventors have found that by forming the core layer in a plurality of layers, it is possible to set the waveguide core arrangement region as desired, thereby eliminating the above problem, The present invention has been completed.

  That is, the optical waveguide of the present invention includes a clad layer and a core layer, and in the optical waveguide through which signal light is incident-propagated-emitted via the core layer, the core layer is at least partially composed of a plurality of layers. It is characterized by being formed.

Further, the optical waveguide manufacturing method of the present invention is the optical waveguide manufacturing method of the present invention, wherein the cladding layer comprises a lower cladding layer, one or more intermediate cladding layers, and an upper cladding layer.
After applying the lower clad layer, the lower mold layer is pressed by pressing a first mold having a concavo-convex pattern formed on the coated lower clad layer, and transferring the concavo-convex pattern to the surface of the lower clad layer. Forming a groove in the cladding layer, and applying a first core layer in the groove;
An intermediate clad layer is applied on the lower clad layer on which the first core layer is formed, and a second mold in which a concavo-convex pattern is formed is pressed against the coated intermediate clad layer, The groove pattern is formed in the intermediate cladding layer by transferring the concavo-convex pattern to the surface of the intermediate cladding layer, and coating the second core layer in the groove is repeated one or more times, so that at least one second layer is formed. A second core layer forming step of forming a core layer;
And an upper clad layer forming step of applying an upper clad layer on the intermediate clad layer on which the second core layer is formed.

  In the optical waveguide manufacturing method of the present invention, a plurality of linear concavo-convex patterns extending substantially in parallel are formed at least partially as the first mold and the second mold that are sequentially used for forming the core layer. The first core layer and the second core layer are formed at least partially in order so as to consist of a plurality of pieces extending substantially in parallel in two directions orthogonal to each other between the layers. Is preferred.

  According to the present invention, by adopting the above-described configuration, it is possible to set the waveguide core arrangement region as desired, so that any portion where the in-plane waveguide core is formed of a plurality of layers can be used from anywhere. Since it becomes possible to take out optical signals, it becomes unnecessary to design and manufacture on a case-by-case basis according to the purpose of use, etc., thereby enabling standardization and commonization of mounting optical waveguides, It has become possible to significantly reduce lead time and reduce costs.

Hereinafter, preferred embodiments of the present invention will be described in detail.
The optical waveguide of the present invention includes a cladding layer and a core layer, and emits, propagates, and emits signal light through the core layer, and the core layer is formed of a plurality of layers at least partially. It is characterized in that

  FIG. 1A shows a schematic perspective view of an example of the optical waveguide of the present invention. The illustrated optical waveguide 10 has two core layers 1A and 1B composed of a plurality of layers extending substantially in parallel in two directions orthogonal to each other between layers. In the illustrated example, the cladding layer is composed of a lower cladding layer 2A, an intermediate cladding layer 2B, and an upper cladding layer 2C. By providing a plurality of core layers 1A and 1B, as shown in the figure, the degree of freedom of the arrangement area of the core layer 1 that propagates light is greatly expanded. Even if the design according to the purpose and the like is not performed, it is possible to appropriately extract light as desired from anywhere as long as the core layer exists.

  In the present invention, as long as the core layer is formed of a plurality of layers, the overall waveguide shape, laminated shape, material, and the like are not particularly limited. In particular, as shown in the drawing, two layers 1A and 1B of the core layers formed of a plurality of layers are at least partially formed from a plurality of layers extending substantially in parallel in two directions orthogonal to each other between the layers. In other words, when the optical waveguide is viewed from the upper surface, it is preferable that the plurality of core layers are arranged so as to form a lattice shape as a whole.

  The optical waveguide of the present invention can be used as an optical wiring in a wiring board, and is particularly preferably used by being disposed together with an electric wiring portion in an electric / light mixed wiring board. FIG. 2 shows a configuration example of an electric / light mixed wiring board as an example of a wiring board using the optical waveguide of the present invention. The illustrated electric / optical mixed wiring board is formed by laminating an optical waveguide 10 of the present invention including a core layer 1 and a clad layer 2 and an electric wiring layer 40 including an electric wiring portion (not shown). For example, the waveguide 10 transmits an optical signal between the light emitting element 31 and the light receiving element 32. In addition, the optical waveguide 10 in a figure is shown in the cross section along the arrangement | positioning direction of the core layer 1B shown to Fig.1 (a). The wiring board according to the present invention is not particularly limited in its specific configuration as long as optical wiring using an optical waveguide can be applied.

  Further, in the present invention, as an intermediate cladding layer between a plurality of core layers, a photo-curing resin having a small absorption loss in the wavelength region of light for transmitting a signal, specifically, an absorption loss of 0.2 dB / It is preferable to provide a layer of a photocurable resin that is not more than cm. By laminating a plurality of core layers via the photo-curable resin layer, it is possible to prevent light leakage to other core layers when light is propagated in one core layer. . Such a photo-curable resin can be appropriately selected from those listed later as photo-curing materials used in the photo-imprint method, and is not particularly limited. In particular, it is preferable to laminate via the same material as the cladding layer.

  FIG. 1B is a schematic perspective view showing only the core layers 1A and 1B of the optical waveguide 10 shown in FIG. As shown in the figure, in the optical waveguide 10 of the present invention, the traveling direction of light can be changed using, for example, a mirror 50 or a slit structure corresponding thereto. The mirror 50 can be provided at a certain angle with respect to the traveling direction of light, for example, in a direction of 45 °. For example, as shown in the drawing, the mirror 50 forms 45 ° with respect to the traveling direction of light and is relative to the core layer surface. Even if two mirrors 50 provided in the direction of 45 ° are combined, it is possible to change the optical path from the lower core layer 1A to the upper core layer 1B, or to extract light from that portion. Become. The mirror 50 can be manufactured by a dicing method using a blade, an optical pin method, a laser method, or the like, or may be coated with gold or the like.

  Accordingly, the setting of the optical path in the optical waveguide 10 of the present invention is easily performed by providing the 45 ° mirror 50 or the like at an appropriate position of the core layer that requires optical path change or optical coupling with other optical waveguide layers. It is possible.

  As a method for producing the optical waveguide of the present invention, a known method can be appropriately used, and is not particularly limited, but a method using a so-called imprint method (also referred to as hot embossing method or nanoimprint method) is preferable. is there.

  FIG. 3 shows an example of a manufacturing process of the optical waveguide 10 of the present invention shown in FIG. 1A using such an imprint method. In the example shown in the figure, (a) after applying the lower clad layer 2A on the substrate 5, (b) pressing the first mold 70 on which the concave / convex pattern is formed on the lower clad layer 2A, The groove 4 is formed by transferring the concavo-convex pattern to the surface of the lower clad layer 2A (imprint process), and then (c) the first core layer 1A is applied in the groove 4 (first core layer formation) Process). Next, (d) an intermediate cladding layer 2B is applied on the lower cladding layer 2A on which the first core layer 1A is formed, and the applied intermediate cladding layer 2B is applied in the same manner as the lower cladding layer 2A. On the other hand, a second mold (not shown) in which a concavo-convex pattern is formed is pressed, and the groove pattern is formed by transferring the concavo-convex pattern to the surface of the intermediate cladding layer 2B, and the second core layer 1B is formed in the groove section. Apply (second core layer forming step). (E) is the side view after 2nd core layer 1B coating seen from the direction orthogonal to (a)-(d). Further, (f) the optical waveguide 10 can be manufactured by coating the upper clad layer 2C on the intermediate clad layer 2B on which the second core layer 1B is formed (upper clad layer forming step).

  In this case, as the first mold 70 and the second mold (not shown) that are sequentially used for forming the core layer by imprinting, a plurality of linear uneven patterns extending substantially in parallel are at least partially. By using the formed one, a plurality of first core layers 1A and second core layers each extending substantially in parallel in two directions orthogonal to each other as shown in FIG. 1B can be formed. When the second core layer is formed of two or more layers, the intermediate clad layer coating shown in (d) and (e), the imprint, and the second core layer coating (second core) The layer forming step) may be repeated twice or more.

  As described above, by forming the groove portion 4 using the imprint method, the development work necessary for the conventional lithography method becomes unnecessary, and it becomes possible to efficiently manufacture in a simple process. Further, since the beam system is unnecessary, the cost of the apparatus can be suppressed, and it is possible to contribute to cost reduction in that an expensive resist material such as a chemical amplification system is unnecessary. Furthermore, since the imprint method can transfer the pattern shape as it is, it can easily obtain the three-dimensional shape as designed, and various cross-sectional shapes such as curved surfaces that cannot be handled by the conventional lithography method. In addition, there is an advantage that an optical waveguide can be formed. In the illustrated example, a mold (template) 70 having a convex portion having a rectangular cross section is used. However, for example, when a core layer having a substantially circular cross section is formed, the cross section of the convex portion is semicircular. A mold that is U-shaped, V-shaped, or the like may be used, and is not particularly limited.

  Here, in the imprint process, as the material of the lower clad layer 2A, either a thermal imprint method using a thermoplastic material or a thermosetting material or a photoimprint method using a photocuring material is preferable. Can be adopted. Among these, in the case of using a thermoplastic material, after pressing the mold 70 at a temperature equal to or higher than its glass transition point, the lower clad layer 2A is cooled and cured before releasing from the mold 70, thereby forming the shape. The lower cladding layer 2A in which the pattern of the groove 4 is formed with high accuracy can be formed. Further, when a thermosetting material is used, the lower clad layer 2A is thermally cured after pressing and before releasing from the mold 70. When a photo-curing material is used, similarly, after pressing, the mold Before releasing from 70, the lower clad layer 2 may be photocured. In any case, since the lower clad layer 2A can be cured before releasing from the mold 70, the pattern of the groove 4 having a desired shape, that is, the pattern of the core layer 1 is formed without causing distortion. be able to. On the other hand, the intermediate clad layer 2B is preferably formed using a photocurable resin among thermoplastic materials, thermosetting materials, and photocurable materials (photocurable resins).

  The clad layer material that can be used in the thermal imprint method is not particularly limited as long as it is a thermoplastic material and a thermosetting material excellent in transparency. For example, examples of the thermoplastic material include polymethyl methacrylate (PMMA), polycarbonate (PC), polystyrene (PS), polyethylene (PE), and polypropylene (PP). These materials may be used alone or blended. In the case of blending, each material to be blended has a structure in which a three-dimensional network structure of each material is interpenetrated (IPN (Inter penetrating networks) structure). Good. A component of the above material may be used as a block to form a copolymer. It is also possible to improve transferability by adding an appropriate amount of solvent to the above material.

  Thermosetting materials include silicon materials, polydimethylsiloxane (PDMS), acrylic resins, polyimide resins, epoxy resins, polyester resins, polyarylate resins, fluorine resins, and deuterated products of these resins. Etc. These materials may be used singly or as a blend, and in the case of blending, the materials to be blended may take a structure (IPN structure) in which the three-dimensional network structure of each material is interpenetrated. A component of the above material may be used as a block to form a copolymer.

  Next, the photoimprint method has an advantage that the process time can be shortened compared with the thermal imprint method because the curing speed of the material is generally high. Photocuring materials that can be used in such a photoimprint method include (a) a dichromate-based photosensitive resin, (b) a photodecomposable photosensitive resin, (c) a photodimerized photosensitive resin, (d) It is classified as a photopolymerization type photosensitive resin.

  (A) Bichromate-based photosensitive resins include natural polymers such as gelatin, glue, egg white, gum arabic, and ceramics, or synthetic polymers such as PVA (polyvinyl alcohol) and polyacrylamide, and heavy chromium. Examples include ammonium acid or potassium dichromate. In addition, (b) photodegradable photosensitive resins include aromatic diazonium salt resins, o-quinonediazide resins, and azide compound-containing resins. (C) Photodimerized photosensitive resins include cinnamic acid ester resins. Resin. Any of these can be used as the lower cladding layer material in the optical imprint method.

Furthermore, (d) as a photopolymerizable photosensitive resin, a photoradical polymerization composition using a radical polymerization reaction of an unsaturated double bond, a photoaddition reaction system using an addition reaction of a thiol group to a double bond Examples thereof include a composition and a photocationic polymerization composition utilizing a ring-opening addition reaction (cationic polymerization) of an epoxy group. Among these, as radical photopolymerization compositions, unsaturated polyesters, unsaturated polyurethanes, unsaturated epoxy resins, oligoester (meth) acrylates, poly (meth) acryloyl groups, maleic acid, fumaric acid groups introduced as functional groups are used. Examples include ether (meth) acrylate. In addition, as a photoaddition reaction system composition utilizing the addition reaction of a thiol group to a double bond, pentaerythritol tetrakis (β-mercaptopropio A compound having a thiol group such as nate), and the photocationic polymerization composition is a photocationic polymerization initiator that releases a Lewis acid such as BF ₃ , SnCl ₄ , or PF ₅ by light irradiation. Used for photo ring-opening polymerization of an epoxy group or the like. Any of the above photopolymerizable photosensitive resins can be used in the photoimprinting method.

  In the imprint method, as described above, a dimensional change occurs due to thermal shrinkage or photocuring shrinkage. Therefore, it is necessary to design the optical waveguide by predicting the amount of change in advance according to the material to be used. Also, it should be noted that the resolution is determined by the mold and that a resin residual film may be generated in the mold.

  The formation of each cladding layer shown in FIGS. 3A and 3D in the case of using the imprint method may be performed by a conventional coating method according to the material to be used, and is not particularly limited. For example, a spin coating method, a comma method, a gravure method, or the like can be used. Moreover, you may laminate | stack the film-form clad layer produced separately as needed. In addition, the formation of the core layer in the groove 4 shown in FIG. 3C is not particularly limited. For example, spin coating, screen printing, offset printing, gravure printing, inkjet, dispenser application, applicator application It is possible to use a conventional method capable of supplying a liquid or at least fluid material, such as inkjet or dispenser application, and in particular, it is preferable to use a method of dispenser application. is there. After the application of the upper cladding layer 2C shown in FIG. 3D, heat or light (ultraviolet rays (UV), electron beams (EB), etc.) is appropriately applied to cure the uncured portion, thereby producing a light guide. The waveguide 10 can be obtained. Note that it is preferable to apply heat or light after the coating of the core layer in order to cure the core layer to some extent and maintain the shape.

  In addition to the materials described above, each cladding layer and core layer can be appropriately selected from conventionally used inorganic materials and organic materials, but the core layer has a higher refractive index than each cladding layer. It is necessary to make a selection in relation to the material of each other layer. Specifically, for example, from various monomers (including solutions), oligomers (including solutions), polymer solutions such as photo-curing materials, thermosetting materials, and thermoplastic materials, such as transparency and heat resistance 20 From the viewpoint of required characteristics and the like, it can be appropriately selected and used.

（式中、Ｒ¹は水素原子またはメチル基を表し、Ｒ²は炭素数８〜２０のアルキル基を表す）で表される化合物、ジ（メタ）アクリルエステル、トリ（メタ）アクリルエステル、さらには、スチレン、ジビニルベンゼン等のスチレン系モノマーなどを挙げることができる。 Among the above monomers, for example, acrylic acid, methacrylic acid and their lower alcohol esters, the following general formula (1),

(Wherein R ¹ represents a hydrogen atom or a methyl group, and R ² represents an alkyl group having 8 to 20 carbon atoms), a di (meth) acryl ester, a tri (meth) acryl ester, May include styrene monomers such as styrene and divinylbenzene.

  Examples of the lower alcohol of the lower alcohol ester of acrylic acid and methacrylic acid include monohydric alcohols having 1 to 5 carbon atoms, preferably 1 to 3 carbon atoms, more preferably methanol.

Moreover, in the compound represented by the general formula (1), R ² representing a higher alkyl group having 8 to 20 carbon atoms preferably has 10 to 16 carbon atoms, more preferably 12 to 14 carbon atoms. The higher alkyl group R ² may be a single alkyl group or a mixed alkyl group, but is most preferably a mixed alkyl group having 12 and 13 carbon atoms. In this case, the ratio of the alkyl group having 12 carbon atoms and the alkyl group having 13 carbon atoms, that is, the ratio of dodecyl (meth) acrylate and tridecyl (meth) acrylate is usually 20:80 to 80:20, and particularly preferably 40:60 to 60:40.

において、ｎが１〜１５、特に１〜１０のものが好ましい。 Di (meth) acrylic esters include diesters of ethylene glycol and (meth) acrylic acid, diesters of polyethylene glycol and (meth) acrylic acid, diols having 3 to 6 carbon atoms in the alkyl chain, and (meth) acrylic acid. And a diester. Examples of tri (meth) acrylic esters include triesters of triols having 3 to 6 carbon atoms in the alkyl chain and (meth) acrylic acid. In addition, as polyethyleneglycol which comprises diester of polyethyleneglycol and (meth) acrylic acid, the following general formula (2),

In which n is 1 to 15, particularly 1 to 10.

  As a method for forming a layer by polymerizing or copolymerizing the above monomers, a curing method using heat or light is generally used, but is not particularly limited. In general, in the case of thermosetting, t-butyl hydroperoxide, di-t-butyl peroxide, lauroyl peroxide, benzoyl peroxide, dimyristyl peroxydicarbonate, t-butyl peroxyacetate, t- Polymerization initiators such as organic peroxides such as butyl peroxy (2-ethylhexanoate) and cumyl peroxy octoate, azo compounds such as azobisisobutyronitrile and azobiscyclohexanenitrile are added, and 50 to A method of polymerizing at 120 ° C. for 1 to 20 hours can be employed. In addition, as a polymerization initiator in the case of photocuring, ketal compounds such as benzyl methyl ketal and acetophenone diethyl ketal, ketone compounds such as α-hydroxyketone, Michler's ketone, α-hydroxycyclohexyl phenyl ketone, and benzophenones such as benzophenone A compound, a metallocene compound such as metallocene, a benzoin compound such as benzoin isopropyl ether, and the like are preferably used.

  In addition, together with the above monomers, one or more of phosphoric acid esters, aromatic carboxylic acid esters, aliphatic carboxylic acids, aliphatic carboxylic acid esters, glycols and glycol (meth) acrylates may be blended and used. From the point of preventing white turbidity when left for a long time under high temperature and high humidity.

  Examples of the polymer include polyester resins such as (meth) acrylic resin (ester of (meth) acrylic acid), polycarbonate (PC), polyethylene terephthalate (PET), polybutylene terephthalate (PBT) (crystal, non-crystalline). Crystal), polysilane, polyethersulfone, polynorbornene, epoxy resin, for example, bisphenol A type, novolac type epoxy resin and polyaminoamide, modified polyaminoamide, modified aromatic polyamine, modified aliphatic polyamine, modified alicyclic polyamine , Mixed cured products with curing agents with active hydrogen such as phenol, polyaryl, polyimide (PI), polycarbodiimide, polyetherimide, polyamideimide, polyesterimide, polyamide (PA), polystyrene (PS), polyester Styrene such as rilonitrile-styrene copolymer (AS), methyl methacrylate-styrene copolymer (MS, MMA-St), styrene-butadiene block copolymer (SBS), acrylonitrile-butadiene-styrene copolymer (ABS) Resins (among other things, SBS and ABS have the advantage of excellent impact resistance), polyarylene ethers such as polyphenylene ether, polyarylate (PAR), polyacetal, polyphenylene sulfide, polysulfone, polyether ether ketone and polyether ketone ketone Polyether ketones, polyvinyl alcohol, polyvinyl pyrrolidone, styrene-ethylene-butadiene-styrene block polymer (SEBS), vinylidene fluoride resin, hexafluoropropylene resin, Etc. can be mentioned fluorine-based resin such as fluoro-acetone resins, among others, (meth) acrylic resin is preferable.

  Other transparent resins include polyvinyl chloride (PVC), cycloolefin polymer (trade name: Arton (JSR Co., Ltd.), Zeonex (Nippon Zeon Co., Ltd., etc.), polypropylene (PP), polyethylene (PE), Examples include triacetyl cellulose (TAC) resin, polyether sulfone (PES), phenol resin, polysulfone (PSF) resin, etc. Among them, styrene resins, particularly those starting from monomers or low molecular weight materials MS resin, (meth) acrylic resin, and epoxy resin.

  In addition to copolymers of acrylic acid, methacrylic acid and their lower alcohol esters and styrenic monomers, transparent resins using monomers in which some or all of the above-described monomers are replaced with fluorine atoms, etc. Can also be used. These materials for the core layer and the upper and lower cladding layers can be used alone or in admixture of two or more. Each cladding layer is preferably formed using the same material from the viewpoint of reducing transmission loss.

  In addition, as the board | substrate 5 used in a manufacturing process, it can select from the conventionally known thing suitably and can be used, It does not restrict | limit in particular. For example, in addition to silicon substrates, quartz substrates, metal foils, glass plates, etc., polymers such as polyethylene terephthalate (PET), acrylic resin films, polycarbonate (PC) films, triacetyl cellulose (TAC) films, polyimide (PI) films, etc. A film or the like can be used. However, when the optical imprint method is used in the above-described imprint process, it is necessary to cure by irradiating light from the substrate 5 side or from the mold side. It is necessary to use it. Furthermore, the solvent used for preparing the coating solution for each layer is not particularly limited, and examples thereof include acetone, methyl ethyl ketone (MEK), ethyl acetate, cellosolve, dioxane, tetrahydrofuran (THF), benzene, cyclohexanone, and the like. The conventional organic solvent can be appropriately selected and used.

  Furthermore, in the present invention, a hard coat or a moisture absorption preventing layer may be laminated on the surface of the optical waveguide 10 produced as described above. In the optical waveguide 10, the portion that transmits information as a light path is the core layer. Therefore, if the core layer is not damaged, there is no problem in the performance as the optical waveguide, but in order to prevent such large damage. In some cases, it may be necessary to provide a hard coat on the surface. Such hard coat materials include (meth) acrylate monomers such as monofunctional (meth) acrylates, bifunctional (meth) acrylates, trifunctional or higher (meth) acrylates, polyfunctional epoxies, and (meth) acrylic oligomers. , Urethane (meth) acrylate, Epoxy (meth) acrylate, Polyester (meth) acrylate, Copolymer (meth) acrylate, Epoxy oligomer added to photoinitiator to polymerize (meth) acrylate or epoxy hard coat material , Silane compounds, organometallic compounds, inorganic oxide fine particles, curing catalysts, and silicone-based hardcoat materials (other than primer treatment may be used) containing other materials as desired, organoalkoxysilanes, alkoxysilanes・ Zirconate-based, water-based Organic hard coat materials such as Kate, aqueous alumina, organoalkoxysilane / resin hybrid, alkoxysilane / zirconate / resin hybrid, water silicate / resin hybrid, and organic such as photocation curable organic / inorganic hybrid materials -Inorganic hybrid type hard coat materials.

Further, the moisture absorption preventing agent is provided for the purpose of preventing the refractive index depending on the optical waveguide material to be used, because the refractive index changes due to moisture absorption and may deviate greatly from the intended design value. In general, a material having high hydrophobicity is used for the moisture absorption preventing layer, and examples thereof include water-repellent paints and fluorine-containing compounds. Also, SiO ₂ , SiN _4, etc. can be used, and these are applied to the upper and lower surfaces of the optical waveguide (film) to prevent moisture absorption of the optical waveguide material itself. In addition, when apply | coating only to one side, anisotropy arises and it may lead to generation | occurrence | production of curvature.

Hereinafter, the present invention will be described specifically by way of examples.
An acrylic resin (manufactured by JSR) is applied to a thickness of 100 μm on a 6-inch diameter quartz glass substrate 5 using a spin coater, and subsequently heated at 100 ° C. for 3 minutes to form a lower clad layer 2A (refractive Ratio 1.51) was formed. Next, a quartz mold 70 is prepared in which the convex side of the concave / convex pattern follows the linear core shape of the core layer 1A shown in FIG. 3, and thermal imprinting is performed at a pressing temperature of 180 ° C. After forming a groove for forming a core layer in layer 2A, a high pressure mercury lamp (365 nm) was used as a light source, and exposure was performed at an illuminance of 20 mW / cm ² and a light amount of 1.0 J / cm ² . The groove had a cross-sectional dimension of 50 μm in width and 50 μm in height, and had a linear planar shape shown in FIG.

Next, an acrylic resin whose refractive index is 3% higher than that of the acrylic resin of the lower clad layer 2A by adding epoxy acrylate as a high refractive index monomer to the acrylic resin used for the lower clad layer 2A. The composition is printed on the linear groove of the lower clad layer 2A by screen printing, heated at a temperature of 100 ° C. for 3 minutes, and then irradiated with a light source of a high-pressure mercury lamp (365 nm) with an illuminance of 20 mW / cm ² and a light quantity. By exposing at 1.0 J / cm ² , a core layer 1A having a refractive index of 1.57, a width of 50 μm, and a height of 50 μm was formed.

Next, a film having a thickness of 100 μm was laminated by spin coating using the same acrylic resin as the lower clad layer 2A as the intermediate clad layer 2B, and heated at a temperature of 100 ° C. for 3 minutes. Thereafter, a quartz mold having a shape in which the convex side of the concavo-convex pattern follows the linear core shape (direction orthogonal to the core layer 1A) of the core layer 1B shown in FIG. 3 is prepared and heated at a press temperature of 180 ° C. After imprinting and forming a groove for forming the core layer in the intermediate clad layer 2B, using a light source of a high-pressure mercury lamp (365 nm), exposure is performed at an illuminance of 20 mW / cm ² and a light amount of 1.0 J / cm ² . A linear groove having a width of 50 μm and a height of 50 μm was formed. Furthermore, the above procedure was repeated again to form a core layer 1B having a refractive index of 1.57, a width of 50 μm, and a height of 50 μm.

Next, as the upper clad layer 2C, a 50 μm film is laminated by spin coating using the same acrylic resin as the lower clad layer 2A, heated at a temperature of 100 ° C. for 3 minutes, and then a high pressure mercury lamp (365 nm). The light source was exposed at an illuminance of 20 mW / cm ² and a light amount of 1.0 J / cm ² . Further, heating was performed at 150 ° C. for 60 minutes to produce a lattice-shaped optical waveguide integrated with the substrate.

  Next, the obtained optical waveguide was immersed in hydrochloric acid to separate the substrate and the waveguide portion. As a result, a film optical waveguide 10 having a lattice-shaped core layer formed by stacking two layers of core shapes shown in FIG. 1 was obtained. It is to be noted that, while the light is incident on the optical waveguide 10 and is emitted again, the light is changed by 90 ° in the vertical direction, that is, from the lower core layer 1A to the upper core layer 1B or vice versa. Or 45 ° mirrors were fabricated at locations where light was emitted to an optical element or a new optical waveguide existing on either the upper or lower side. For the processing, a 90 ° V-order diamond blade with a blade tip shape was used, and cutting was performed while applying the blade perpendicular to the core layer of the optical waveguide. Through the above series of steps, the optical waveguide of the present invention in which the core layer is formed of a plurality of layers at least partially can be manufactured.

(A) is a schematic perspective view of the optical waveguide of this invention, (b) is a schematic perspective view which takes out and shows only the core layer. It is an example of 1 structure of the electrical / light mixed wiring board as an example of the wiring board using the optical waveguide of this invention. It is a schematic explanatory drawing which shows an example of the manufacturing process of the optical waveguide using the imprint method.

Explanation of symbols

1A, 1B Core layer 2A Lower clad layer 2B Intermediate clad layer 2C Upper clad layer 4 Groove 5 Substrate 10 Optical waveguide 31 Light emitting element 32 Light receiving element 40 Electrical wiring layer 50 Mirror 70 Mold

Claims (9)

  An optical waveguide that includes a clad layer and a core layer, and receives, propagates and emits signal light through the core layer, wherein the core layer is formed of a plurality of layers at least partially. Optical waveguide.   The optical waveguide according to claim 1, wherein the optical waveguide is disposed in an electric / light mixed wiring board together with the electric wiring portion.   The optical waveguide according to claim 2, wherein the optical waveguide is laminated with an electric wiring layer including the electric wiring portion and disposed in the electric / optical mixed wiring board.   4. The structure according to claim 1, wherein two of the core layers formed of the plurality of layers are formed of a plurality of at least a portion extending substantially in parallel in two directions orthogonal to each other between the layers. The optical waveguide according to one item.   The optical waveguide according to claim 1, wherein the plurality of core layers are laminated via a photocurable resin.   The optical waveguide according to claim 1, comprising an organic compound.   The optical waveguide according to claim 1, wherein at least one mirror is provided in a direction that forms 45 ° with respect to the traveling direction of light. In the method for manufacturing an optical waveguide according to any one of claims 1 to 7, wherein the cladding layer includes a lower cladding layer, one or more intermediate cladding layers, and an upper cladding layer.
After applying the lower clad layer, the lower mold layer is pressed by pressing a first mold having a concavo-convex pattern formed on the coated lower clad layer, and transferring the concavo-convex pattern to the surface of the lower clad layer. Forming a groove in the cladding layer, and applying a first core layer in the groove;
An intermediate clad layer is applied on the lower clad layer on which the first core layer is formed, and a second mold in which a concavo-convex pattern is formed is pressed against the coated intermediate clad layer, The groove pattern is formed in the intermediate cladding layer by transferring the concavo-convex pattern to the surface of the intermediate cladding layer, and coating the second core layer in the groove is repeated one or more times, so that at least one second layer is formed. A second core layer forming step of forming a core layer;
And an upper clad layer forming step of applying an upper clad layer on the intermediate clad layer on which the second core layer is formed.   As the first mold and the second mold that are sequentially used to form the core layer, at least a part of the first mold and the second mold that are formed with a plurality of linear concavo-convex patterns extending substantially in parallel are used. 9. The method of manufacturing an optical waveguide according to claim 8, wherein the core layer and the second core layer are sequentially formed so as to consist of a plurality of cores extending at least partially in two directions orthogonal to each other at least partially.

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