JP2005208285A - Method of manufacturing high molecular optical waveguide - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing a high-precision high molecular optical waveguide easily on a substrate. <P>SOLUTION: The method of manufacturing the high molecular optical waveguide is characterized by including steps of: (1) preparing a rubber casting mold of a composite lamination structure in which a rubber layer is embedded composed of a setting resin for forming a rubber casting mold with a recessed part corresponding to the projection part of an optical waveguide core, in recessed part for forming the rubber layer of a rigid substrate having such recessed part; (2) preparing a clad base material which is set in a manner that a core region adjacent to the optical waveguide core has a higher surface energy than in regions other than the core region; (3) forming a core-forming setting resin layer near the core region by applying unhardened core-forming setting resin on the clad base material; (4) charging the core-forming setting resin in the recessed part of the rubber casting mold by sticking the recessed part of the rubber casting mold closely to the core-forming setting resin layer of the clad base material; (5) curing the charged core-forming setting resin; (6) peeling off the rubber casting mold from the clad base material; and (7) forming a clad layer on the clad base material on which the optical waveguide core is formed. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a method for manufacturing a polymer optical waveguide, and more particularly to a method for manufacturing a polymer optical waveguide capable of forming a polymer optical waveguide on a buried silicon substrate or an electronic circuit substrate.

  The polymer waveguide manufacturing method includes (1) a method in which a film is impregnated with a monomer, a core portion is selectively exposed to change the refractive index, and the film is bonded (selective polymerization method), and (2) a core layer. And a method of forming a cladding portion by reactive ion etching after applying the cladding layer (RIE method), and (3) exposure and development using an ultraviolet curable resin in which a photosensitive material is added to a polymer material. (4) Method of using injection molding, (5) Method of changing the refractive index of the core by exposing the core after coating the core and cladding layers (Photo bleaching method) has been proposed.

However, the selective polymerization method of (1) has a problem in film lamination, and the methods of (2) and (3) are expensive because the photolithographic method is used. There is a problem in the accuracy of the diameter. Further, the method (5) has a problem that a sufficient difference in refractive index between the core layer and the clad layer cannot be obtained.
At present, the practical methods excellent in performance are only the methods (2) and (3), but there is a problem of cost as described above. None of the methods (1) to (5) is applicable to forming a polymer waveguide on a flexible plastic substrate having a large area.

In addition, as a method of manufacturing a polymer optical waveguide, a core substrate is formed by filling a polymer substrate material for a core into a pattern substrate (cladding) on which a groove pattern serving as a capillary is formed, and then curing the core layer. In this method, the polymer precursor material is thinly filled and cured not only in the capillary groove but also between the pattern substrate and the flat substrate. As a result of forming a thin layer having the same composition as the core layer, there is a problem that light leaks through the thin layer.
As one method for solving this problem, Debit Hart uses a clamping jig to fix the pattern substrate on which a groove pattern serving as a capillary is formed and a flat substrate, and further, the contact portion between the pattern substrate and the flat substrate. A method of manufacturing a polymer optical waveguide by sealing the resin with a resin and then reducing the pressure and filling a capillary with a monomer (diallyl isophthalate) solution was proposed (see Patent Document 1 below). In this method, instead of using the polymer precursor material as the core forming resin material, the viscosity of the filling material is reduced by using a monomer, and the capillary is filled using the capillary phenomenon so that the monomer is not filled except the capillary. It is a method to do.

However, since this method uses a monomer as the core forming material, there is a problem that the volumetric shrinkage when the monomer is polymerized to become a polymer is large, and the transmission loss of the polymer optical waveguide is increased.
In addition, this method is a complicated method such as fixing the pattern substrate and the flat substrate with a clamp, or additionally sealing the contact portion with resin, so that it is not suitable for mass production, and as a result, cost reduction is expected. I can't. Further, it cannot be applied to the production of a polymer optical waveguide using a film having a thickness of mm order or 1 mm or less as a clad.

  Recently, George M. Whitesides and others at Harvard University have proposed a method called capillary micromolding as one of the soft lithography as a new technology for creating nanostructures. This is because a master substrate is made using photolithography, and the nanostructure of the master substrate is copied to a PDMS mold using the adhesion and easy peelability of polydimethylsiloxane (PDMS). This is a method of pouring and solidifying a liquid polymer. The following non-patent document 1 describes detailed explanation articles.

Alternatively, a patent on capillary micromolding has been filed by Kim Enoch et al. Of George M. Whitesides group at Harvard University (see Patent Document 2 below).
However, even if the manufacturing method described in this patent is applied to the manufacture of a polymer optical waveguide, the core portion of the optical waveguide has a small cross-sectional area, so that it takes time to form the core portion and is not suitable for mass production. In addition, when the monomer solution is polymerized to become a polymer, the volume is changed, the core shape is changed, and the transmission loss is increased.

B. Michel et al. Of the IBM Zurich Research Institute have proposed a high-resolution lithography technique using PDMS, and reported that this technique can achieve a resolution of several tens of nanometers. Detailed commentary articles are described in Non-Patent Document 2 below.
Thus, the soft lithography technique using PDMS and the capillary micromold method are techniques that have recently attracted attention mainly in the United States as nanotechnology.

  However, when an optical waveguide is manufactured by using the micromold method as described above, the volume shrinkage during curing is reduced (thus, transmission loss is reduced), and a filling liquid (monomer or the like) is used to facilitate filling. It is impossible to achieve a low viscosity. Therefore, if priority is given to reducing the transmission loss, the viscosity of the filling liquid cannot be reduced below a certain limit, the filling speed becomes slow, and mass production cannot be expected. The micromold method is based on the premise that a glass or silicon substrate is used as the substrate, and does not consider the use of a flexible film substrate.

  On the other hand, the present inventors have already proposed a method in which a flexible film base material is also used as a clad base material to form a polymer waveguide on the film base material (Japanese Patent Application No. 2003-58871, Japanese Patent Application No. 2003-58872). With this polymer optical waveguide manufacturing method, it has become possible to manufacture a flexible polymer optical waveguide that has been impossible in the past with high accuracy and at low cost.

  By the way, recently, in IC technology and LSI technology, in order to suppress signal delay and noise and improve the degree of integration, optical wiring is performed between equipment devices, between boards in equipment equipment, and in chips instead of metal wiring. For example, attention is focused on connecting a light emitting element and a light receiving element with an optical waveguide (see, for example, Patent Documents 3 to 5 below).

  The optical wiring element described in Patent Document 3 includes an incident side mirror for causing light from the light emitting element to enter the core, and an emission side mirror for emitting light from the core to the light receiving element, A clad layer is formed in a concave shape at a position corresponding to an optical path from the light emitting element to the incident side mirror and from the output side mirror to the light receiving element, and the light from the light emitting element and the light from the output side mirror are converged. In addition, the optical wiring element described in Patent Document 4 is such that the light incident end face of the core is formed to be convex toward the light emitting element, and the light from the light emitting element is converged to suppress the waveguide loss. . The optical wiring elements described in Patent Documents 3 and 4 have a complicated structure, and therefore, a very complicated process is required for their production.

  Further, Patent Document 5 describes an optoelectronic integrated circuit in which a polymer optical waveguide circuit is directly assembled on an optoelectronic circuit board in which electronic elements and optical elements are integrated. Is produced by a photolithographic method which is expensive. Therefore, the optoelectronic integrated circuit is inevitably expensive.

  In order to solve these problems, the present inventors, as Japanese Patent Application No. 2002-187474, have a complex structure in which a light emitting part or a light receiving part is further provided directly on the core end face of the polymer optical waveguide. Accordingly, an optical element that can be manufactured at a low cost by an extremely simplified method has been provided.

For example, the polymer optical waveguide according to Japanese Patent Application Nos. 2003-58871 and 2003-58872 is provided with a conductive circuit for a light receiving element and / or a light emitting element, such as an electric signal and a power source. When assembling the optical element according to Japanese Patent Application No. 2002-187474, it is more convenient.
Japanese Patent No. 3151364 US Pat. No. 6,355,198 JP 2000-39530 A JP 2000-39531 A JP 2000-235127 A SCIENTIFIC AMERICAN SEPTEMBER 2001 (Nikkei Science December 2001 issue) IBM J. REV. & DEV. VOL. 45 NO. 5 SEPTEMBER 2001

  The present invention has been made on the basis of the above-mentioned demands, and an object of the present invention is to provide a method for producing a polymer optical waveguide capable of easily producing a high-precision polymer optical waveguide on a substrate. .

Means for solving the problems are as follows.
<1> 1) Composite in which a rubber layer made of a curable resin for forming a rubber mold having a concave portion corresponding to a convex portion of an optical waveguide core is embedded in a concave portion for forming a rubber layer of a rigid substrate having a concave portion for forming a rubber layer. A step of preparing a rubber mold having a laminated structure, 2) a step of preparing a clad substrate in which a core region in contact with the optical waveguide core is set to have a surface energy higher than a region other than the core region, and 3) the clad base A step of applying an uncured core-forming curable resin on the material to form a core-forming curable resin layer in the vicinity of the core region, and 4) forming a recess of the rubber mold into the core of the clad substrate. A step of filling the concave portion of the rubber mold with the core-forming curable resin, 5) a step of curing the filled core-forming curable resin, and 6) a step of removing the rubber mold from the clad substrate. Peeling process, 7) A method for producing a polymer optical waveguide, comprising a step of forming a clad layer on a clad substrate on which an optical waveguide core is formed.

<2> The concave portion for rubber layer formation of the rigid substrate includes a groove portion that is substantially similar to the concave portion of the rubber layer, and is 1 μm to 3 mm larger than the groove depth and width of the concave portion of the rubber layer, and The method for producing a polymer optical waveguide according to <1>, wherein the maximum thickness of the rigid substrate is 0.05 to 40 mm.

<3> The core-forming curable resin is photocurable, and the rigid substrate and the rubber layer are made of a material that transmits light having a wavelength for photocuring the core-forming curable resin. The method for producing a polymer optical waveguide according to <1> or <2>.

<4> The high transmittance according to <3>, wherein the rigid substrate and the rubber layer have a transmittance of 40% / mm or more with respect to light having a wavelength for photocuring the curable resin for core formation. This is a method of manufacturing a molecular optical waveguide.

<5> The above <1> to <4, wherein the rubber mold includes a reinforcing member that reinforces the rigid substrate, and the reinforcing member is provided with a discharge port for the core-forming curable resin. > A method for producing a polymer optical waveguide according to any one of the above.

<6> The method for producing a polymer optical waveguide according to <5>, wherein the reinforcing member is made of a metal material, a ceramic material, or a plastic material.

<7> The core resin layer according to any one of <1> to <6>, wherein the core cured resin layer has a space for stress relaxation in a portion communicating with the discharge portion at both ends of the recess. This is a method for producing a polymer optical waveguide.

<8> The method for producing a polymer optical waveguide according to any one of <1> to <7>, wherein the rubber mold forming curable resin is a silicone rubber material.

<9> The method for producing a polymer optical waveguide according to any one of <1> to <8>, wherein a clad layer is provided on the entire surface or a part of the surface of the clad substrate. .

<10> The method for producing a polymer optical waveguide according to any one of <1> to <9>, wherein the rubber mold and the clad substrate are adhered in a reduced pressure environment in the step 4). .

<11> The method for producing a polymer optical waveguide according to <10>, wherein the pressure in the reduced pressure environment is 500 hPa or less.

<12> From the above <1> to <1>, the surface energy of the region in contact with the optical waveguide core on the clad substrate in the step 2) is 10 μN / cm or more higher than the surface energy of the region other than the region. 11>. The method for producing a polymer optical waveguide according to any one of 11).

<13> The method for producing a polymer optical waveguide according to any one of <1> to <12>, wherein the maximum value of the thickness of the rubber layer is 5 μm to 5 mm.

<14> The rubber mold according to any one of <1> to <13>, wherein the rubber mold has a share rubber hardness of a curable resin for forming a rubber mold in a range of 5 to 45. This is a method of manufacturing a molecular optical waveguide.

<15> The method for producing a polymer optical waveguide according to any one of <1> to <14>, wherein the rubber layer has a surface energy of 70 μN / cm to 350 μN / cm.

<16> The polymer optical waveguide according to any one of <1> to <15>, wherein the rubber layer has a surface roughness of 0.3 μm or less in contact with the core-forming cured resin. It is a manufacturing method.

<17> Any one of <1> to <16>, wherein the rubber layer has a transmittance for light having a wavelength for photocuring the curable resin for core formation of 50% / mm or more. It is a manufacturing method of the polymer optical waveguide of description.

<18> The polymer light according to any one of <1> to <17>, wherein the clad substrate is a ceramic resin composite substrate, a film substrate, a ceramic substrate, or a silicon wafer. It is a manufacturing method of a waveguide.

<19> The method for producing a polymer optical waveguide according to any one of <1> to <18>, wherein the curable resin for core formation has a viscosity before curing of 50 mPa · s to 2000 mPa · s. It is.

<20> The difference between the refractive index of the clad base material and the refractive index of the curable resin for core formation is 0.01 or more, according to any one of <1> to <19>, This is a method for producing a polymer optical waveguide.

  In the method for producing a polymer optical waveguide according to the present invention, a clad layer or a clad layer pattern is formed on the entire surface in advance on a base material, and then a polymer optical waveguide is formed thereon. An opto-electric hybrid type circuit board in which optical elements and electronic elements are mixedly mounted at a high density can be easily manufactured close to each electronic device in which an optical waveguide is formed in advance.

  Further, in the method for producing a polymer optical waveguide of the present invention, the core forming curable resin is applied in a thin film by setting a surface energy difference between the optical waveguide core region and the other region (non-core region). Then, when the mold having the rubber layer is tightly bonded, the uncured curable resin liquid for forming the core is integrated and gathered into the concave portion which is the optical waveguide core portion of the rubber mold, and the optical waveguide core portion is made of rubber. Since the surface energy of the non-core region on the clad substrate formed in the mold is lower than that of the optical waveguide core region, the adhesive strength of the uncured core-forming curable resin liquid is low. Therefore, the optical waveguide core can be automatically and easily shaped by the two phenomena.

  Further, since the rubber mold is a mold of a composite structure of a rigid substrate and a rubber layer, there is an effect that the mold is not unnecessarily deformed, a mold shift due to vibration does not occur, and a highly accurate mold can be achieved. In addition, since the rigid substrate is included in the rubber mold, alignment can be performed with high accuracy, and a highly accurate alignment process with the clad substrate is facilitated. In addition, it is possible to easily achieve efficient pressure contact adhesion to the clad substrate, and it is easy to obtain adhesion reliability between the rubber mold and the substrate, or it is easy to use a rubber layer with low surface energy or a material with low rubber hardness. Because it comes out, it is easy to obtain optical surface properties (super smooth surface). In particular, if the rubber mold satisfies the characteristic range of rubber material (rubber hardness, rubber material, rubber thickness, surface energy, surface smoothness, etc.), high quality can be easily obtained.

  Further, according to the method for producing a polymer optical waveguide of the present invention, the production of the polymer optical waveguide is very simple and low cost, and the production of the polymer optical waveguide for various substrates is also simple and low in cost. Can be possible. In addition, the polymer optical waveguide to be formed can be freely set in shape, etc., so that it is possible to form an optical waveguide even on the uneven surface of an electronic device, and an electronic circuit such as a silicon wafer is embedded or formed. It is easy to make waveguides on and near the top. In addition, although the manufacturing process is simple, it has a feature that it can achieve optical characteristics with extremely high accuracy in shape reproducibility and low waveguide loss. Furthermore, even when a flexible film substrate is used as the substrate with a clad layer, a polymer optical waveguide that can be freely loaded into various devices can be obtained.

The method for producing a polymer optical waveguide of the present invention is characterized by having the following steps 1) to 6).
1) A composite laminated structure in which a rubber layer made of a curable resin for forming a rubber mold having a concave portion corresponding to a convex portion of an optical waveguide core is embedded in a concave portion for forming a rubber layer of a rigid substrate having a concave portion for forming a rubber layer. Step 2 of preparing a rubber mold 2) Step of preparing a clad substrate in which the core region in contact with the optical waveguide core is set to have a surface energy higher than the region other than the core region 3) On the clad substrate, A step of applying a curable resin for forming a core for forming a core and forming a curable resin layer for forming a core in the vicinity of the core region 4) The recesses of the rubber mold are formed on the curable resin layer for forming a core of the clad substrate. Step 5) Filling the concave portion of the rubber mold with the core-forming curable resin 5) Curing the filled core-forming curable resin 6) Separating the rubber mold from the clad substrate 7) Optical waveguide core But Forming a cladding layer on the made the clad substrate

First, one embodiment of the method for producing a polymer optical waveguide of the present invention will be described with reference to FIGS.
FIGS. 1A to 1C are conceptual diagrams showing a process for producing a rubber mold using a core master 10 on which convex portions 12 corresponding to an optical waveguide core are formed.
First, as shown in FIG. 1A, a core master 10 is prepared in which convex portions 12 corresponding to the optical waveguide core are formed. FIG. 1A shows a cut surface obtained by cutting the core master 10 at a right angle to the longitudinal direction of the convex portion 12.

  FIG. 1B is a diagram showing a state in which the rubber layer forming concave portion 20b of the rigid substrate 20a is in close contact with the surface of the core master 10 on which the convex portion 12 is formed. The recess 20b for forming the rubber layer has a groove depth and width larger than the convex portion 12 of the core master 10, is substantially similar to the convex 12, includes the same number of grooves 20c as the convex 12, and each of the core master 10 The convex part 12 is surrounded by each groove part 20c. As shown in FIG. 1B, there is a space between the convex portion 12 of the core master 10 and the rubber-forming concave portion 20b of the rigid substrate 20a.

  The space is filled with a curable resin for forming a rubber mold and cured to form a rubber layer 23. Then, in a state where the rigid substrate 20a and the rubber layer 23 are integrated, they are separated from the master 10. Next, the both ends of the mold are cut so that the concave portion 22 is exposed, thereby corresponding to the entry portion 22a (see FIG. 4) for filling the concave portion 22 with the core-forming curable resin and the convex portion 12. A discharge part 22b (see FIG. 4) for discharging the resin from the recess 22 is formed to produce a rubber mold 25 (see FIG. 1C).

  Next, with reference to FIG. 2, the step of preparing a clad substrate in which the region in contact with the optical waveguide core is set so that the surface energy is higher than the region other than the region (step 2) will be described. . First, the clad substrate 30 is prepared. FIG. 2A is a view corresponding to FIG. 1A showing a cut surface of the clad substrate. Next, a pattern mask 60 having a transmission pattern corresponding to the optical waveguide core is provided above the clad substrate 30 and irradiated with UV light toward the pattern mask 60 (FIG. 2B). Then, a pattern 30b having a surface energy higher than that of the light irradiation portion is formed in the light irradiation portion (core region) corresponding to the optical waveguide core.

  Next, the coating device 62 is used to form a UV-curable core-forming curable resin (liquid) 40a having a volume corresponding to the optical waveguide core in the form of a thin film on the clad substrate 30. Apply (FIG. 2C). After application, the core-forming curable resin naturally gathers on the pattern 30b having a high surface energy (FIG. 2D).

  The rubber mold 25 and the clad substrate 30 produced as described above are pressure-contacted in a reduced pressure environment so that the recess 22 of the rubber mold 25 and the pattern 30b of the clad substrate 30 coincide (FIG. 3). (See (A)-(B) and FIG. 4). FIG. 3B shows a cross-sectional view cut along a longitudinal direction of the concave portion in a state where the rubber mold 25 and the clad substrate 30 are in close contact with each other (A-A cut surface in FIG. 4). When the rubber mold 25 and the clad substrate 30 are in close contact with each other as described above, the core-forming curable resin 40a gathered in the pattern 30b is filled in the recess 22 of the rubber mold 25 and has a low surface energy pattern. The core-forming curable resin 40a is removed from the region other than 30b, and the core-forming curable resin 40a exists only in the recess 22 of the rubber mold 25.

  Next, UV light is irradiated to cure the core-forming curable resin 40a filled in the recess 22 of the rubber mold 25 (FIG. 3C), and the rubber mold 25 is peeled off. FIG. 3D shows a cut surface obtained by cutting the optical waveguide core 40 formed on the clad substrate 30 at a right angle to the longitudinal direction of the core.

  Furthermore, the polymer optical waveguide 60 is manufactured by forming the clad layer 50 that is a hardened layer of the core-forming curable resin on the core-forming surface of the clad substrate 30. FIG. 3E shows a cut surface obtained by cutting the polymer optical waveguide 60 perpendicularly to the longitudinal direction of the core.

  In addition, an example in which a reinforcing member that reinforces a rigid substrate of a rubber mold is provided and a clad layer 32 is provided on the side of the clad substrate 30 on which the optical waveguide core is formed is shown. 5 (A) to 5 (C) are the same as the steps shown in FIGS. 1 (A) to 1 (C) (however, FIG. 5 (A) shows a rigid substrate or the like as the core master). FIGS. 5D to 5F are common to the steps shown in FIGS. 3B to 3E. Starting from the core master 10 (omitted), the process up to the step of forming the optical waveguide core 60 on the clad substrate 30 on which the clad layer 32 is formed is shown.

  Further, FIG. 6 shows an example in which a film to be a clad is adhered to the clad substrate on which the core is formed by an adhesive. 6 (A) is FIG. 5 (A), FIG. 6 (B) is FIG. 5 (C), and FIGS. 6 (C) to 6 (E) are FIGS. 5 (D) to 5 (F). The process from the core master 10 to the process of forming the optical waveguide core 40 on the clad substrate 30 is shown in common with the process expressed by FIG. 6F shows a polymer optical waveguide 60 obtained by bonding a clad layer (clad film) 52 to the core forming surface of the clad base material 30 using an adhesive layer 54 at right angles to the longitudinal direction of the core. Shows the cut surface.

Below, the manufacturing method of the polymer optical waveguide by this invention is demonstrated in order of a process.
1) A composite laminated structure in which a rubber layer made of a curable resin for forming a rubber mold having a concave portion corresponding to a convex portion of an optical waveguide core is embedded in a concave portion for forming a rubber layer of a rigid substrate having a concave portion for forming a rubber layer. Step of Preparing Rubber Mold The production of the rubber mold is preferably performed using a core master having a convex portion corresponding to the optical waveguide core, but is not limited thereto. Hereinafter, a method using the core master will be described.

<Preparation of core master>
Conventional methods such as a photolithography method and an RIE method can be used without particular limitation for the production of a core master having a convex portion corresponding to the optical waveguide core. Further, the method (Japanese Patent Application No. 2002-10240) for producing a polymer optical waveguide by the electrodeposition method or the photo-deposition method previously filed by the present applicant can also be applied to produce the core master. The size of the convex portion corresponding to the optical waveguide core formed on the core master is generally about 5 to 500 μm, preferably about 40 to 200 μm, and is appropriately determined according to the use of the polymer optical waveguide. For example, in the case of a single mode optical waveguide, a core of about 10 μm square is generally used, and in the case of a multimode optical waveguide, a core of about 50 to 100 μm square is generally used. An optical waveguide having a larger core part of about μm is also used.

<Production of rubber mold>
As described above, the rubber mold includes a rigid substrate having a rubber layer forming concave portion, and a rubber layer made of a rubber mold forming curable resin having a concave portion corresponding to the optical waveguide core convex portion in the rubber layer forming concave portion. A composite laminated structure in which is embedded. Such a rubber mold is formed by applying or injecting a curable resin for forming a rubber mold into a recess for forming a rubber layer of a rigid substrate, and performing a curing process such as a heat treatment if necessary. The curable resin is cured, and then the integrated rigid substrate and rubber layer are peeled off from the master.

  As described above, the rigid substrate has a rubber layer forming recess, and a rubber layer is formed in the rubber layer forming recess. In other words, when the rigid substrate is brought into close contact with the core master, a space is formed between the rigid substrate, the core master, and the core convex portion, and the space is filled with a curable resin for forming a rubber mold, and the resin is cured to rubber. Form a layer. Moreover, it is preferable that the rubber layer forming concave portion is formed with a groove portion having a shape substantially similar to the concave portion corresponding to the optical waveguide core convex portion of the rubber layer. The groove is formed so as to correspond to the recess formed in the rubber layer (see FIG. 1B). The groove portion is preferably 1 μm to 3 mm larger than the groove depth and width of the concave portion of the rubber layer, and more preferably 0.03 to 1.0 mm larger. In this case, the maximum thickness of the rigid substrate is preferably 0.05 to 40 mm, and more preferably 0.1 to 10 mm. By setting the size of the groove and the thickness of the rigid substrate within the above ranges, the effects of the present invention can be more suitably exhibited.

  Examples of the material constituting the rigid substrate include a film base, a ceramic resin composite base, a ceramic base, a silicon wafer base, a resin base, a glass base, and the like. A substrate, a highly smooth film substrate, a heat-resistant film substrate, a silicon compound substrate, and an acrylic resin substrate are preferable.

  In addition, when a photo-curable resin is used as the rubber mold-forming curable resin, the rigid substrate is a material that transmits the wavelength light for photo-curing of the rubber mold-forming curable resin in order to cure the resin. It is necessary to.

  When a photocurable resin is used as the core-forming curable resin, it is necessary that the rigid substrate and the rubber layer be made of a material that transmits wavelength light for photocuring in order to cure the resin. Specifically, the transmittance for light having a wavelength for photocuring the core-forming curable resin is preferably 40% / mm or more, and more preferably 70% / mm or more.

  Further, in the rubber mold, a discharge port for filling an excessive core-forming curable resin is formed in the concave portion corresponding to the convex portion, but the forming method is not particularly limited. A convex part corresponding to the discharge port can be provided in advance on the master, but as a simple method, for example, a mold rubber layer is formed on the master with a mold-forming curable rubber liquid, and then the mold is removed by peeling. Then, a method of forming a discharge port by cutting both ends of the mold so that the concave portion is exposed is mentioned. The rubber material is made from the core molding master. The rubber material has a rubber hardness of 10 to 35, and has a soft property. By using soft rubber elasticity, the molding property of peeling after the core is formed is improved. I will give you the ability. In particular, high surface smoothness of molded products is possible with rubber with low rubber hardness and rubber material with low surface energy, and the rubber layer is highly accurate and maintains molding accuracy against vibration and pressure changes when the core material is injected. For this reason, it is possible to select an appropriate value for the thickness of the rubber having a highly rigid recess reinforcing material that is relatively thin with respect to the thickness of the rubber and has durability against deformation and vibration.

  It is also effective to provide through holes communicating with the rubber mold recess at both ends of the recess. The through hole can connect the inside of the recess to the suction / discharge device by inserting the discharge pipe therein. Depending on the pitch of the recesses, the through-holes may be provided corresponding to the respective recesses, or one through-hole communicating with each recess may be provided.

  The thickness of the rubber layer is appropriately determined in consideration of handling properties as a mold, but generally the maximum value of the thickness of all layers is about 5 μm to 5 mm. Due to this thickness and rubber hardness (elasticity), deformation peelability at the time of peeling can be made appropriate, interface fracture from the core master can be suppressed, and core surface damage at the time of peeling at the time of core molding can also be suppressed. In that sense, the rubber hardness, thickness, and surface energy of the curable resin for rubber mold formation are related to each other, and are important control characteristic values depending on required molding accuracy. By satisfying these requirements, an optical waveguide core can be easily and partially formed even on a substrate having an electronic device or an electronic circuit in the vicinity.

Further, the core master may be subjected to a release treatment such as application of a release agent in advance to promote peeling from the rubber mold. However, it reduces the formability of the surface.
As the curable resin for forming a rubber mold, the cured product can be easily peeled off from the core master, has a certain level of mechanical strength and dimensional stability as a mold (repeatedly used), and has a hardness that maintains a concave shape ( (Hardness) and good adhesion to the clad substrate. Various additives may be added to the rubber mold-forming curable resin as necessary.

  The rubber mold forming curable resin can be applied or cast on the surface of the core master, and the convex portions corresponding to the individual optical waveguide cores formed on the core master must be accurately copied. Therefore, it is preferable to have a viscosity below a certain limit, for example, about 500 to 7000 mPa · s. Moreover, a solvent can also be added for viscosity adjustment to such an extent that the bad influence of a solvent does not appear.

  As the rubber mold forming curable resin, from the viewpoint of peelability, mechanical strength and dimensional stability, hardness, and adhesion to the clad substrate, the cured silicone rubber (silicone elastomer) or silicone resin is used. A curable organopolysiloxane is preferably used. The curable organopolysiloxane preferably contains a methylsiloxane group, an ethylsiloxane group, or a phenylsiloxane group in the molecule. The curable organopolysiloxane may be a one-component type or a two-component type used in combination with a curing agent, and may be a thermosetting type or a room temperature curable type (for example, cured with moisture in the air). The other) (further ultraviolet curing or the like) may be used.

  The curable organopolysiloxane is preferably a silicone rubber after curing, which is usually referred to as a liquid silicone rubber (including “liquid” which has a high viscosity such as a paste). The two-part type used in combination with a curing agent is preferable. Among them, the addition type liquid silicone rubber cures uniformly in a short time on the surface and the inside, and at that time, a by-product is formed. It is preferably used because it has no or little, excellent releasability and low shrinkage.

  Among the liquid silicone rubbers, liquid dimethylsiloxane rubber is particularly preferable from the viewpoint of adhesion, peelability, strength and hardness controllability. In addition, since the cured product of liquid dimethylsiloxane rubber generally has a low refractive index of about 1.43, a rubber mold made therefrom can be used as a clad layer as it is without being peeled off from the clad substrate. In this case, it is necessary to devise such that the rubber mold, the filled core forming resin, and the clad substrate are not peeled off.

  The viscosity of the liquid silicone rubber is from the viewpoint of accurately copying the convex portion corresponding to the optical waveguide core and facilitating defoaming by reducing the mixing of bubbles, and from the viewpoint of forming a rubber mold having a thickness of several millimeters. 100 to 7000 mPa · s is preferable, and about 1000 to 4000 mPa · s is more preferable. If it is 500 mPa · s or less, the injection efficiency is too good, and it may enter between the clad substrate and the rubber interface of the rubber mold, and deterioration of the shape accuracy may be observed. Moreover, even if the injection assisting means is exhausted when the pressure is 7000 mPa · s or more, the injection rate does not increase, and the productivity may decrease.

  Further, the surface energy of the outermost layer contacting the core material of the rubber mold is in the range of 70 μN / cm to 350 μN / cm, preferably 120 μN / cm to 210 μN / cm. This is preferable from the viewpoint of the penetration rate of the curable resin for formation. If it is 70 μN / cm or less, liquid penetration may be difficult, and if it is 350 μN / cm or more, the adhesiveness of the surface becomes high when the rubber mold is peeled off on the surface of the cured molded product, and the surface property of the core part may be damaged. .

  The share rubber hardness of the rubber layer of the rubber mold is preferably 10 to 40, and more preferably 15 to 30. The shear rubber hardness of a layer (rubber layer) other than the outermost layer is preferably 45 to 120, and more preferably 70 to 110. By setting the share rubber hardness within the above range, it is preferable from the viewpoint of mold taking performance, maintenance of the shape of the recess, and peelability. If it is less than 10, mold accuracy may deteriorate, and there may be a problem in shape reproducibility. If it exceeds 120, proper elasticity cannot be obtained when the mold is peeled off from the rubber mold. May cause damage.

  The surface roughness (root mean square roughness (RMS)) of the rubber layer of the rubber mold is 0.5 μm or less, preferably 0.1 μm or less, more preferably 0.05 μm or less. Optical loss can be greatly reduced in wave characteristics. The surface roughness is required to be half or less of the wavelength of the light to be used. When the surface roughness is one tenth or less, the waveguide loss due to the core surface roughness of the light is almost negligible. The surface roughness is required to be half or less of the wavelength of the light to be used. When the surface roughness is one tenth or less, the waveguide loss due to the core surface roughness of the light is almost negligible.

  Moreover, it is preferable that the rubber mold forming curable resin of the rubber layer of the rubber mold has a light transmittance of 50% / mm or more in the ultraviolet region and / or the visible region. In particular, it is preferable to have a light transmittance of 50% / mm or more with respect to light having a wavelength of 365 nm. The rubber mold-forming curable resin is preferably light transmissive in the visible region when positioning the rubber mold in close contact with the clad substrate in the following step 4). This is because it can be observed that the core-forming curable resin is filled in the rubber mold recesses in the same step, and the completion of filling can be easily confirmed. The rubber mold is preferably light transmissive in the ultraviolet region because, when an ultraviolet curable resin is used as the core-forming curable resin, the rubber mold is passed through the rubber mold to perform ultraviolet curing. The transmittance of the mold in the ultraviolet region (350 nm to 400 nm) is preferably 50% or more.

  The curable organopolysiloxane, especially the liquid silicone rubber that becomes the silicone rubber after curing, has excellent contradictory properties of adhesion to the clad substrate and peelability, has the ability to copy the nanostructure, and the silicone rubber and the clad substrate. Can be prevented even from entering the liquid. A rubber mold using such a silicone rubber copies the core master with high accuracy and adheres well to the clad base material. Therefore, only the recess between the rubber mold and the clad base material is efficiently filled with the core forming resin. In addition, the clad substrate and the rubber mold can be easily peeled off. Therefore, from this rubber mold, a polymer optical waveguide whose shape is maintained with high accuracy can be produced very simply.

2) Step of preparing a clad substrate in which the core region in contact with the optical waveguide core is set to have a surface energy higher than the region other than the core region. Region in which the optical waveguide core is to be formed in the clad substrate ( The core region) is set so that the surface energy is higher than the region other than the core region. Thus, in order to set the surface energy to be different depending on the region in the clad substrate, for example, 1) A metal mask is placed over the clad substrate, and high-concentration ozone by corona discharge or the like is sprayed thereon, The surface energy of the part that is not hidden by the metal mask is increased. 2) The exposed part and the unexposed part are made with resist by the photolithography process, and then the acid treatment and alkali treatment are performed to increase the surface energy of the exposed part. 3) Various surface energy patterns can be set on the surface of the organic material of the clad substrate, such as excimer light is irradiated onto the clad substrate in a pattern using a pattern mask to increase the surface energy of the exposed portion. it can.

  As described above, in the present invention, the core region in the clad substrate is set so that the surface energy is higher than the region other than the core region, but the surface energy between the core region and the region other than the core region is set. The difference is preferably 10 to 500 μN / cm, more preferably 50 to 200 μN / cm, considering the efficiency with which the core-forming curable resin collects in the core region.

  The clad substrate used in the present invention is preferably a ceramic resin composite substrate, a film substrate, a ceramic substrate, or a silicon wafer. In the case of a clad base material having an appropriate refractive index, it may be left as it is. However, if the refractive index control is necessary, a resin coat or an inorganic material is deposited on the entire surface or a part of the surface of the clad base material by the PVD method. Those provided with a cladding layer are also used. The refractive index of the cladding layer is smaller than 1.55 and more preferably smaller than 1.50. In particular, it is necessary to be 0.05 or more smaller than the refractive index of the core material. Further, as the characteristics of the clad layer, in the smoothness, Ra is 0.1 μm or less, more preferably 60 nm or less, the smoothness is excellent, and the rubber mold has excellent adhesion with the rubber mold. What does not produce a void other than the concave portion is preferable. Further, when the clad substrate is not very good in adhesion with the rubber mold and / or the core, treatment with an ozone atmosphere and ultraviolet irradiation with a wavelength of 300 nm or less are performed to improve the adhesion with the rubber mold or the like. It is preferable.

  Among plastic substrates, polymer optical waveguides using flexible film substrates can be used as couplers, optical interconnections between boards, optical demultiplexers, and the like. The film base material has optical properties such as refractive index, light transmittance, mechanical strength, heat resistance, adhesion to a rubber mold, and flexibility depending on the use of the polymer optical waveguide to be produced. (Flexibility) and the like.

Examples of the material for the film base include acrylic resins (polymethyl methacrylate, etc.), alicyclic acrylic resins, styrene resins (polystyrene, acrylonitrile / styrene copolymers, etc.), olefin resins (polyethylene, polypropylene, ethylene Propylene copolymer, etc.), alicyclic olefin resin, vinyl chloride resin, vinylidene chloride resin, vinyl alcohol resin, vinyl butyral resin, arylate resin, fluorine-containing resin, polyester resin (polyethylene terephthalate, polyethylene naphthalate) Phthalate, etc.), polycarbonate resin, cellulose di- or triacetate, amide resin (aliphatic, aromatic polyamide, etc.), imide resin, sulfone resin, polyether sulfone resin, polyether ether ketone resin, polyphenyle Sulfide resins, polyoxymethylene-based resin or a blend of the resin, and the like.
As the alicyclic acrylic resin, OZ-1000, OZ-1100 (manufactured by Hitachi Chemical Co., Ltd.) or the like in which an aliphatic cyclic hydrocarbon such as tricyclodecane is introduced into an ester substituent is used.

  The alicyclic olefin resins include those having a norbornene structure in the main chain, and those having a norbornene structure in the main chain and an alkyloxycarbonyl group in the side chain (alkyl groups having 1 to 6 carbon atoms or cycloalkyl). And those having a polar group such as a group). Among them, the alicyclic olefin resin having a norbornene structure in the main chain and a polar group such as an alkyloxycarbonyl group in the side chain as described above has a low refractive index (refractive index is around 1.50, core clad It is particularly suitable because it has excellent optical properties such as a high refractive index and a high optical transparency, excellent adhesion to a rubber mold, and excellent heat resistance.

In order to secure a difference in refractive index from the core, the refractive index of the film base and the clad base is preferably less than 1.55, preferably less than 1.53.
The thickness of the film substrate is appropriately selected in consideration of flexibility, rigidity, ease of handling, etc., and is generally preferably about 0.1 mm to 0.5 mm.

The electronic circuit is formed by applying a conductive layer on the entire surface of the clad base material where the optical waveguide is not formed, partially or by a PVD method or a foil bonding method, and using an ordinary method (a photolithography method, a dry etching method). , Laser heating scanning method, electric discharge machining method, etc.). As an electronic circuit conductive layer, a single layer or a composite thin film layer of a metal such as chromium, copper, aluminum, gold, molybdenum, nickel, silver, platinum, iron, titanium, zinc, tungsten, tin, or an alloy containing these metals In addition, a conductive metal compound, a thin film obtained by adding a conductive fine powder such as carbon black to a polymer material, or the like is used. In particular, the conductive pattern of the electronic circuit is gold, copper, aluminum, molybdenum, nickel that is suitable for wire bonding and flip chip mounting to enable mounting of electrical continuity with each electronic device and light control device. And its alloys are particularly good.
The thickness of the conductive layer is suitably about 0.05 to 30 μm. More preferably, a thickness of 0.2 to 2 μm is appropriate.
Moreover, it is preferable to provide the electroconductive layer for electronic circuits in the optical waveguide non-formation surface of a clad base material, and it is also possible to laminate | stack.

3) A step of applying an uncured core-forming curable resin on the clad substrate to form a core-forming curable resin layer in the vicinity of the core region. In this step, in the step 2) An uncured curable resin for core formation is applied on the prepared clad substrate.

  As the core-forming curable resin, resins such as radiation curable, electron beam curable, and thermosetting can be used, and among them, an ultraviolet curable resin is preferably used.

  As the ultraviolet curable resin or thermosetting resin for forming the core, an ultraviolet curable or thermosetting monomer, an oligomer, or a mixture of a monomer and an oligomer is preferably used. In particular, the mixing of the oligomer helps the curing speed and improves the accuracy of the shape.

In addition, an epoxy-based, polyimide-based, or acrylic-based ultraviolet curable resin is preferably used as the ultraviolet curable resin.
Since the core-forming curable resin is filled in the gap formed between the rubber mold and the film substrate (the concave part of the rubber mold), the core-forming curable resin used has a sufficiently low viscosity so that it is possible. It is necessary to be. The viscosity of the curable resin before curing is 50 mPa · s to 2000 mPa · s, preferably 100 mPa · s to 1000 mPa · s, more preferably 300 mPa · s to 700 mPa · s. It is preferable in terms of goodness and low light loss. If it is 50 mPa · s or less, it may enter an unnecessary gap between the rubber mold and the substrate and impair the moldability, and if it is 2000 mPa · s or more, the permeation rate becomes extremely slow and productivity may be lowered.

  In addition, it is preferable that the volume change before and after curing of the curable resin is small in order to accurately reproduce the original shape of the convex portion corresponding to the optical waveguide core formed on the core master. For example, a decrease in volume causes a large waveguide loss. Therefore, the curable resin desirably has a volume change as small as possible, and is desirably 10% or less, preferably 0.01 to 4%. Lowering the viscosity using a solvent is preferably avoided if possible because the volume change before and after curing is large. In particular, a material system with a volume of 0.01% or less or volume expansion reduces the peeling efficiency from the rubber mold and causes surface degradation such as surface breakage when peeling from the rubber mold, resulting in reduced surface smoothness and optical waveguide. Loss increases, which is not preferable.

  In order to reduce the volume change (shrinkage) after curing of the core-forming curable resin, a polymer can be added to the resin. The polymer preferably has compatibility with the core-forming curable resin and does not adversely affect the refractive index, elastic modulus, and transmission characteristics of the resin. In addition to reducing the volume change by adding a polymer, the viscosity and the glass transition point of the cured resin can be highly controlled. Examples of the polymer include acrylic, methacrylic acid, and epoxy polymers, but are not limited thereto.

The refractive index of the cured product of the core-forming curable resin is preferably in the range of 1.20 to 1.60, more preferably in the range of 1.4 to 1.6, and the refractive index of the cured product falls within the above range. More than one kind of resin with different refractive index is used.
The refractive index of the cured product of the curable resin for core formation needs to be larger than that of the film base material (including the clad layer in the process of the following 7) to be the clad. The difference in refractive index between the core and the clad (clad substrate and clad layer) is 0.01 or more, preferably 0.05 or more.

  The core-forming curable resin is applied by a highly accurate coating amount control method such as a spin coating method, a dipping coating method, a roll coating method, or a fountain head coating method.

  0.5-500 micrometers is preferable and, as for the film thickness of the coating film of curable resin for core formation, 1-50 micrometers is more preferable.

  The core-forming curable resin applied as described above naturally gathers in the core region having a high surface energy. That is, the core-forming curable resin is gathered in a pattern set on the clad substrate, and the core-forming curable resin layer corresponding to the optical waveguide core is formed. The transition to the next step 4) is performed after the core-forming curable resin has gathered in the core region as described above.

4) A step of bringing the concave portion of the rubber mold into close contact with the curable resin layer for core formation of the clad base material and filling the concave portion of the rubber mold with the curable resin for core formation The rubber mold produced in the step 1) And the clad base material on which the core-forming curable resin layer is formed in the step 3) are adhered so that the recesses of the rubber mold coincide with the clad base material. When the rubber mold and the clad substrate are brought into close contact with each other in this manner, there is a difference in surface energy between the core region and the other region (non-core region). The optical waveguide core portion is formed in a rubber mold by being integrated into a concave portion which is a portion. Since the surface energy of the non-core region on the clad substrate is lower than that of the optical waveguide core region, the adhesive force of the uncured core-forming curable resin liquid is low, and is excluded from the clad substrate surface by the rubber mold. As described above, the core-forming curable resin is filled in the recess of the rubber mold.

  The above steps are preferably performed under a reduced pressure environment. In particular, in the process of bringing the rubber mold and the clad substrate into close contact with each other in a reduced pressure environment, the adsorbed gas on the surface of the molded product and the dissolved gas in the liquid can be suppressed, so that unnecessary gas can be prevented from entering the core. Further, since the adhesion of the rubber mold to the substrate can be increased from the atmosphere, it is possible to prevent or reduce molding accuracy defects and defective molded products. Specifically, the pressure in a reduced pressure environment is preferably 500 hPa or less, and more preferably 1 to 200 hPa.

5) Step of curing the filled core-forming curable resin The filled core-forming curable resin is cured. In order to cure the ultraviolet curable resin, an ultraviolet lamp, an ultraviolet LED, a UV irradiation device or the like is used. Further, heating in an oven or the like is used to cure the thermosetting resin.

6) Step of peeling the rubber mold from the clad substrate After the step 5), the rubber mold is peeled from the clad substrate. Further, the rubber mold used in the steps 1) to 5) can be used as it is for the cladding layer as long as the conditions such as the refractive index are satisfied. In this case, it is not necessary to peel off the rubber mold as it is as the cladding layer. Sometimes used. In this case, it is preferable to ozone-treat the rubber mold in order to improve the adhesion between the rubber mold and the core material.

7) A step of forming a clad layer on the clad base material on which the optical waveguide core is formed. A clad layer is formed on the clad on which the core is formed. A clad base material used in the same manner), a layer cured by applying a curable resin for cladding, a polymer film obtained by applying a solvent solution of a polymer material and drying, and the like It is done. As the curable resin for cladding, an ultraviolet curable resin or a thermosetting resin is preferably used. For example, an ultraviolet curable or thermosetting monomer, an oligomer, or a mixture of a monomer and an oligomer is used.

In order to reduce the volume change (shrinkage) after curing of the curable resin for forming a clad, the polymer has compatibility with the resin and does not adversely affect the refractive index, elastic modulus and transmission characteristics of the resin (for example, Methacrylic acid or epoxy) can be added to the resin.
When a film is used as the clad layer, it is bonded using an adhesive. At this time, it is desirable that the refractive index of the adhesive is close to the refractive index of the film. As the adhesive to be used, an ultraviolet curable resin or a thermosetting resin is preferably used. For example, an ultraviolet curable or thermosetting monomer, an oligomer, or a mixture of a monomer and an oligomer is used.
In order to reduce the volume change (shrinkage) after curing of the ultraviolet curable resin or the thermosetting resin, a polymer similar to the polymer added to the cladding layer can be added.

  The difference in refractive index between the clad substrate and the clad layer is preferably small, and the difference is within 0.1, preferably within 0.05, more preferably within 0.001, and most preferably no difference. Is preferable from the viewpoint of light confinement.

  In the method for producing a polymer optical waveguide of the present invention, in particular, a liquid silicone rubber that is cured as a curable resin for forming a rubber mold and becomes a rubbery state, particularly a liquid dimethylsiloxane rubber, and a norbornene structure in the main chain as a clad substrate And the use of an alicyclic olefin resin having a polar group such as an alkyloxycarbonyl group in the side chain has particularly high adhesion between the two, there is no deformation of the rubber mold concave structure, and the concave structure Even if the cross-sectional area is extremely small (for example, a 10 × 10 μm rectangle), the concave portion can be quickly filled with the curable resin.

  In the method for producing a polymer optical waveguide of the present invention, it is preferable that the rigid substrate is reinforced with a reinforcing member in the step 1). The material of the reinforcing member is made of a metal material, a ceramic material, a hard plastic material, a ceramic resin composite material or the like, and the maximum value of the thickness is suitably about 0.5 mm to 40 mm. Further, the reinforcing member is provided with outlets (see 24b and 24c indicated by phantom lines in FIG. 10A) for discharging excess curable resin for core formation at both ends of the recess. A discharge pipe is inserted and connected to the discharge port. It is preferable to provide a plurality of outlets so that the reduced pressure state is uniform at the outlets of the respective recesses. It is preferable to provide a plurality of discharge ports so that the reduced pressure state is not biased in the rubber mold recess.

  By providing a reinforcing member, even when the pressure change of the rubber mold occurs, the rubber mold and the clad base material are displaced, and the rubber mold deforms due to vibration in the whole or part of the rubber mold. And the adhesion with the clad substrate can be prevented, and the filling rate can be increased without sacrificing the accuracy of the core shape.

  An embodiment using a rubber mold provided with a reinforcing member will be described with reference to FIGS.

FIG. 7A shows a perspective view in which a rubber mold provided with a reinforcing member is closely attached to the clad substrate 30. In FIG. 7A, reference numeral 24 denotes a reinforcing member, and the rubber mold recess forming region (irradiation region of ultraviolet rays or the like) has a structure in which the reinforcing member is notched. Reference numerals 26a, 26b, 28a, and 28b denote discharge pipes for discharging excess curable resin for core formation, and reference numeral 90 denotes a slight displacement between the reinforcing member 24 and the clad substrate 30. In addition, it is a screw for fixing both. Reference numeral 20 a denotes a rubber layer of a rubber mold, and this portion is not covered with the reinforcing member 24.
FIG. 7B is a cross-sectional view taken along the line AA of FIG. 7A, and 22 indicates a rubber mold recess. FIG. 7C is a cross-sectional view taken along the line BB of FIG. 7A, and a gap 22a for stress relaxation communicating with the discharge part of the core-forming curable resin at both ends of the rubber mold recess. 22b.

  The modes shown in FIGS. 8A to 8C show an example in which a rubber mold provided with the same reinforcing member as that in FIG. 7 is used, and the clad base material is arranged so that the clad base material 30 and the rubber mold are not misaligned. A holding member 92 having a holding portion (concave portion) to be held is used, and this is also effective particularly when a flexible film is used as a clad substrate. In this example, a light-transmitting top plate 24a such as a quartz plate, a glass plate, or a hard plastic plate is used in a rubber mold recess forming region (an irradiation region such as ultraviolet rays). Since other configurations are the same as those in FIGS. 7A to 7C, the same components are denoted by the same reference numerals and description thereof is omitted.

  9A to 9C, the holding member 92 is provided with a fixing fitting groove 93, while the rubber mold reinforcing member 24 is provided with a fitting member 29, and the fitting member 29 is used for fitting. It is the structure which fits in the groove | channel 93 and fixes. Since other configurations are the same as those in FIGS. 7A to 7C, the same components are denoted by the same reference numerals and description thereof is omitted.

  When a plurality of optical waveguide cores are formed on the clad substrate, it is preferable to provide a gap for pressure relaxation in the rubber layer of the rubber mold provided with the reinforcing member as described above. The void portion means a common space that communicates with all the discharge portions of the discharge portion (excess of the core forming curable resin) at one end portion of the plurality of concave portions of the rubber mold. Further, by providing a gap in the discharge part, the negative pressure can be relaxed and made uniform, and the resin filling in each recess of the rubber mold is made uniform.

  The cross-sectional area of the gap is preferably 5 to 20000 times the total cross-sectional area of all the recesses, and more preferably 500 to 2500 times. (Here, “total cross-sectional area of all recesses” means the sum of the areas of the end portions of the recesses communicating with each other through the gap.)

FIG. 10 is a cross-sectional view showing an example of a rubber mold in which a gap is provided in the discharge part.
FIG. 10A is a diagram showing a cut surface obtained by cutting a rubber mold so that a rubber mold concave portion and a void portion appear. In FIG. 10A, 20 is a rubber mold, 21 is a void portion, 22 is a concave portion, Reference numeral 24 denotes a reinforcing member, and 24b and 24c denote discharge portions provided on the reinforcing member, respectively. FIG. 10B shows a cut surface obtained by cutting FIG. 10A along the line AA.

  In the present invention as described above, the production process of the polymer optical waveguide is very simple and low-cost, and the formation of the polymer optical waveguide on the electronic circuit mixed substrate can be executed with a simple process and low cost. In addition, since the polymer optical waveguide to be formed can be freely set in shape etc., it is possible to form a waveguide even on an uneven surface of an electronic device, and it is formed by embedding an electronic circuit such as a silicon wafer. It is easy to produce a waveguide at the top and in the vicinity. In addition, despite the simple manufacturing process, it is also a great feature that it has extremely high-precision shape reproducibility and low waveguide loss. Furthermore, even when a flexible film substrate is used as the substrate with a clad layer, a polymer optical waveguide that can be freely loaded into various devices can be obtained.

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to these examples.
[Example 1]
<Production of rubber mold>
A UV curable thick film resist (SU-8, manufactured by Micro Chemical Co., Ltd.) is applied to a quartz substrate by spin coating, prebaked at 80 ° C., exposed to a high pressure mercury lamp through a photomask, developed, and cross-sectioned. Formed five convex portions (width: 50 μm, height: 50 μm, pitch 500 μm, length: 50 mm). Next, this was post-baked at 120 ° C. to prepare a core master.

  Subsequently, a reinforcing member (thickness: made of aluminum having a thickness of 1.5 mm) provided with an opening corresponding to the ultraviolet irradiation portion and having six discharge ports was prepared, and a quartz transparent rigid substrate having a thickness of 2 mm was prepared. A recess for forming a rubber layer including a groove portion (width: 100 μm, height: 100 μm, pitch: 500 μm, length: 50 mm, 5 pieces) having substantially the same shape and the same pitch as the convex portion of the core master is formed by a photolithography process and a hook. It was produced by an acid etching process and integrated with a reinforcing member. This reinforcing member was placed on the core master.

Next, a thermosetting liquid dimethylsiloxane rubber (manufactured by Dow Corning Asia Co., Ltd .: SYLGARD 184, viscosity 5000 mPa · s) and a curing agent thereof are mixed from the opening of the reinforcing member as a rubber mold forming curable resin. Poured again (at this time, the end of the core master protrusion was not covered with the rubber), and heated at 130 ° C. for 30 minutes for final curing.
After curing, when the rubber layer, the permeable rigid substrate, and the reinforcing member are peeled off from the core master, the core has a concave portion corresponding to the convex portion, and the concave portion of the core-forming curable resin is formed in the concave portion. A rubber mold with a discharge outlet was formed. The share rubber hardness of the rubber layer was 18.

<Formation of high surface energy pattern on clad substrate>
In a state where arton film (film thickness: 100 μm) was washed as a clad substrate, a positive resist (manufactured by Tokyo Ohka Kogyo Co., Ltd.) was applied with a spinner and prebaked at 80 ° C. for 2 minutes to obtain a 1.2 μm resist film. Next, using a vacuum contact mask aligner for UV exposure with a high-pressure mercury lamp, pattern exposure is performed using a waveguide core pattern mask, development is performed with an alkaline agent, water washing is performed, and post-baking is performed at 130 ° C. for 2 minutes. went. Thereafter, the entire surface was irradiated with ultraviolet light having a wavelength of 172 nm, and a core part pattern having a high surface energy of 410 μN / cm was formed on the clad substrate irradiated with the light. The cladding substrate that was not irradiated with light was 300 μN / cm. Next, the resist film was peeled off by applying ultrasonic waves while being immersed in an acetone solution, and then washed with water. A high surface energy pattern was formed on the Arton film.

<Formation of optical waveguide core and cladding layer>
An uncured core liquid, which is an ultraviolet curable resin having a viscosity of 1300 mPa · s (manufactured by JSR Corporation: PJ3001), is applied to the clad substrate having the high surface energy pattern as a core-forming curable resin by a roll coater. A thin film having a wet thickness of 160 μm was obtained. When allowed to stand for 2 minutes, the uncured core liquid gathered around the high surface energy pattern. Next, in a reduced pressure environment of 100 hPa, the rubber mold was pressed and adhered onto the clad base material with a core-forming curable resin layer. As a result, excess uncured core liquid was ejected from each outlet of the reinforcing member of the rubber mold. Further, at the discharge port of the rubber mold, vacuum suction of −50 kPa by static pressure was performed through a vacuum deaeration tube. In 5 seconds, the UV curable resin was filled into the core recess of the rubber mold.

The vacuum degassing tube was removed from the rubber mold, and 30 mW / cm ² of UV light was irradiated from the exposure opening of the rubber mold for 10 minutes to cure the core-forming curable resin. When the rubber mold was peeled off, a core having a refractive index of 1.57 was formed on the film.

Further, an ultraviolet curable resin (manufactured by JSR Co., Ltd.) having a refractive index after curing of 1.51 which is the same as that of Arton Film is applied on the entire surface of the core forming surface of ARTON film (clad substrate), and then 30 mW / UV light of cm ² was irradiated for 10 minutes to cure with ultraviolet rays (film thickness after curing: 10 μm). A flexible polymer optical waveguide was obtained. The average waveguide loss of this polymer optical waveguide was 0.22 dB / cm.

[Comparative Example 1]
A polymer optical waveguide was manufactured by forming an optical waveguide core and a clad layer on an ARTON film using a rubber mold of a uniform rubber material having a share rubber hardness of 80. The average waveguide loss of the three optical waveguide cores of this polymer optical waveguide was 6.3 dB / cm. The other two could not confirm optical waveguide. Degradation of the shape of the optical waveguide core was confirmed with a microscope.

[Example 2]
<Production of rubber mold>
An ultraviolet curable thick film resist solution (SU-8, manufactured by Micro Chemical Co., Ltd.) is applied to a quartz substrate by spin coating, prebaked in a heating oven at 80 ° C., exposed through a photomask with a high pressure mercury lamp, and then developed. Through the process, a core master having 10 fine protrusions (width: 80 μm, height: 80 μm, pitch: 1 mm, length: 100 mm) having a square cross section was produced. Each was post-baked at 120 ° C. One end of each of the convex portions thus produced is made of a pressure relief gap having a height of 2 mm, a width (direction perpendicular to the convex portion) of 10 mm, and a longitudinal length of the substrate of 20 mm and a rectangular cross section. Convex parts were formed and used as core masters.

  Next, a reinforcing member made of aluminum is manufactured, and a quartz glass plate is disposed in the opening for exposure, and a 2 mm-thick acrylic transparent rigid substrate is formed in a substantially similar shape at the same pitch as the convex portion of the core master. The recesses for forming the rubber layer including the groove portions (width: 250 μm, height: 250 μm, pitch: 1 mm, length: 100 mm, 10) were produced by a photolithography process and an etching process and integrated with the reinforcing member.

  Next, a thermosetting silicone rubber oligomer (manufactured by Dow Corning Asia Co., Ltd .: SYLGARD 184, dimethylpolysiloxane) is placed on the convex side of the core master so that one end in the longitudinal direction of the convex part is exposed. Then, the coating was performed so as to cover the end of the void-forming convex portion at the other end. The reinforcing member was pressed and fixed from above. Then, it is cured by heating at 125 ° C. for 8 minutes, so that one end of the convex portion in the longitudinal direction is partially exposed and the end of the void-forming convex portion at the other end is covered. Applied. From this, the reinforcing member integrated with the rigid substrate was pressed and fixed. Then, it heated and hardened at 125 degreeC for 30 minute (s), and the transparent rigid board | substrate, silicone rubber, and the reinforcement member were integrated. The thickness of the rubber layer was 10 mm. Next, this was peeled off from the core master to obtain a rubber mold. In the silicon rubber layer of the rubber mold, a 40 μm square concave portion, a core forming curable resin discharge portion, and a void portion were formed. The shear rubber hardness of the rubber layer was 14.

<Formation of high surface energy pattern on clad substrate>
In a state where Arton film (film thickness 150 μm) is washed as a clad substrate, pattern light is irradiated for 1.5 minutes with UV light having a wavelength of 172 nm through a mask, and a high surface of 430 μN / cm is applied on the irradiated film substrate. An energy core pattern was formed. The film base with no light irradiation was 310 μN / cm. A high surface energy pattern was obtained on the Arton film.

<Formation of optical waveguide core and cladding layer>
Under a reduced pressure environment of 150 hPa, the rubber mold was brought into pressure contact with the clad substrate having the uncured core liquid layer, and the arton film was brought into pressure contact. Thereafter, each outlet tube of the reinforcing member of the rubber mold was detached. An ultraviolet curable resin (manufactured by JSR: PJ3001) having a viscosity of 500 mPa · s gathered in the rubber mold concave portion due to the difference in surface energy and injected into the concave core portion.
After completion of filling, the vacuum degassing tube was removed from the rubber mold, and 80 mW / cm ² of UV light was irradiated for 10 minutes through a quartz window of the rubber mold to cure the core-forming curable resin.

When the rubber mold was peeled off, a core having a refractive index of 1.57 was formed on the film.
Next, after applying a thermosetting resin (entire surface made by JSR Co., Ltd.) whose refractive index after curing is 1.51, the same as that of the film, on the film core forming surface, a film having a thickness of 100 μm is laminated and cured by heating. As a result, a flexible polymer optical waveguide was obtained. The average waveguide loss of this polymer optical waveguide was 0.19 dB / cm. In the same manner as in Example 1, good light guiding to the optical waveguide was confirmed.

It is a conceptual diagram which shows the process of producing a rubber mold. It is a conceptual diagram which shows the process of setting a core area | region to a clad base material. It is a conceptual diagram which shows the process of sticking a rubber mold to a clad base material and completing an optical waveguide. It is a perspective view which shows the state which closely_contact | adhered the casting_mold | template to the base material for clads. It is a conceptual diagram which shows another aspect of the manufacturing method of the polymer optical waveguide of this invention. It is a conceptual diagram which shows another aspect of the manufacturing method of the polymer optical waveguide of this invention. It is a conceptual diagram for demonstrating the core material filling process using the rubber mold provided with the reinforcement member. It is a conceptual diagram for demonstrating the other core material filling process using the rubber mold provided with the reinforcement member. It is a conceptual diagram for demonstrating the other core material filling process using the rubber mold provided with the reinforcement member. It is a figure which shows the example which provided the space | gap for stress relaxation in the rubber layer of the rubber mold.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Core master 12 Convex part 20a corresponding to optical waveguide core Rigid board | substrate 20b Rubber layer formation recessed part 20c Groove part 21 Cavity part 22 Rubber mold recessed part 22a Cavity part (discharge part of curable resin for core formation)
22b Cavity (core discharging resin for curable resin)
23 Rubber layer 24 Reinforcing member 24b 24c Discharge portion 25 Rubber mold 26a 26b Injection tube 28a 28b Discharge tube 30 Clad base material 31 Conductive pattern 40a Core-forming curable resin 40 Core 50 Clad layer 60 Polymer optical waveguide

Claims (20)

  1) A composite laminated structure in which a rubber layer made of a curable resin for forming a rubber mold having a concave portion corresponding to a convex portion of an optical waveguide core is embedded in a concave portion for forming a rubber layer of a rigid substrate having a concave portion for forming a rubber layer. A step of preparing a rubber mold, 2) a step of preparing a clad base material in which a core region in contact with the optical waveguide core is set to have a surface energy higher than a region other than the core region, and 3) on the clad base material A step of applying an uncured core-forming curable resin to form a core-forming curable resin layer in the vicinity of the core region, and 4) forming a concave portion of the rubber mold into the core-forming curable resin of the clad substrate. A step of closely adhering to the resin layer and filling the concave portion of the rubber mold with the core-forming curable resin, 5) a step of curing the filled core-forming curable resin, and 6) a step of peeling the rubber mold from the clad substrate. 7) Light Manufacturing a polymer optical waveguide comprising a step, of forming a clad layer on the waveguide core is clad substrates formed.   The concave portion for forming the rubber layer of the rigid substrate includes a groove portion that is substantially similar to the concave portion of the rubber layer and that is 1 μm to 3 mm larger than the groove depth and width of the concave portion of the rubber layer, and of the rigid substrate. 2. The method for producing a polymer optical waveguide according to claim 1, wherein the maximum thickness is 0.05 to 40 mm.   The core-forming curable resin is photo-curable, and the rigid substrate and the rubber layer are made of a material that transmits light having a wavelength for photo-curing the core-forming curable resin. Item 3. A method for producing a polymer optical waveguide according to Item 1 or 2.   4. The polymer optical waveguide according to claim 3, wherein the rigid substrate and the rubber layer have a transmittance of 40% / mm or more with respect to light having a wavelength for photocuring the curable resin for core formation. Production method.   5. The rubber mold according to claim 1, wherein the rubber mold has a reinforcing member that reinforces the rigid substrate, and the reinforcing member is provided with a discharge port for a curable resin for forming a core. A method for producing a polymer optical waveguide as described in 1. above.   The method for producing a polymer optical waveguide according to claim 5, wherein the reinforcing member is made of a metal material, a ceramic material, or a plastic material.   7. The polymer optical waveguide according to claim 1, wherein the cured resin layer for the core has a gap portion for stress relaxation at a portion communicating with the discharge portion at both ends of the concave portion. Manufacturing method.   The method for producing a polymer optical waveguide according to any one of claims 1 to 7, wherein the curable resin for forming a rubber mold is a silicone rubber material.   The method for producing a polymer optical waveguide according to any one of claims 1 to 8, wherein a clad layer is provided on the entire surface or a part of the surface of the clad substrate.   The method for producing a polymer optical waveguide according to any one of claims 1 to 9, wherein the rubber mold and the clad substrate are adhered in a reduced pressure environment in the step 4).   The method for producing a polymer optical waveguide according to claim 10, wherein the pressure in the reduced pressure environment is 500 hPa or less.   The surface energy of a region in contact with the optical waveguide core on the clad substrate in the step 2) is 10 μN / cm or more higher than the surface energy of a region other than the region. The manufacturing method of the polymer optical waveguide as described in a term.   13. The method for producing a polymer optical waveguide according to claim 1, wherein the maximum value of the thickness of the rubber layer is 5 μm to 5 mm.   The polymer optical waveguide according to any one of claims 1 to 13, wherein the rubber mold has a share rubber hardness of a curable resin for forming a rubber mold in a range of 5 to 45. Production method.   The method for producing a polymer optical waveguide according to any one of claims 1 to 14, wherein the rubber layer has a surface energy of 70 µN / cm to 350 µN / cm.   16. The method for producing a polymer optical waveguide according to claim 1, wherein a surface roughness of a surface of the rubber layer in contact with the core-forming cured resin is 0.3 μm or less.   The polymer according to any one of claims 1 to 16, wherein the rubber layer has a transmittance for light having a wavelength for photocuring the curable resin for core formation of 50% / mm or more. Manufacturing method of optical waveguide.   The method for producing a polymer optical waveguide according to any one of claims 1 to 17, wherein the clad substrate is a ceramic resin composite substrate, a film substrate, a ceramic substrate, or a silicon wafer. .   19. The method for producing a polymer optical waveguide according to claim 1, wherein a viscosity before curing of the core-forming curable resin is 50 mPa · s to 2000 mPa · s.   The polymer optical waveguide according to any one of claims 1 to 19, wherein a difference between a refractive index of the clad substrate and a refractive index of the curable resin for core formation is 0.01 or more. Manufacturing method.

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