JP5678583B2 - Method for manufacturing grooved optical waveguide, grooved optical waveguide, and optoelectric composite substrate - Google Patents

Description

  The present invention relates to an optical waveguide manufacturing method, an optical waveguide obtained by the manufacturing method, and an optoelectric composite substrate including the optical waveguide.

  In high-speed and high-density signal transmission between electronic devices and between wiring boards, signal transmission interference and attenuation become barriers in conventional transmission using electric wiring, and the limits of high-speed and high-density are beginning to appear. In order to overcome this problem, a technique for connecting between electronic elements and wiring boards with light, so-called optical interconnection, has been proposed, and various studies have been made regarding the combination of electrical wiring and optical wiring. As an optical transmission line, it is desirable to use an optical waveguide that has a higher degree of freedom of wiring and can be densified than an optical fiber, and among them, an optical waveguide that uses a polymer material that is excellent in processability and economy. Promising.

  Also, in the above optical waveguide singulation process, the optical waveguide is processed into a shape having a mirror for optical path conversion, and an optical / electrical composite substrate or an optical / electrical composite module including an optical waveguide with a mirror and an electric wiring board is produced. it can. For example, Patent Documents 1 and 2 disclose a waveguide film type optical module including an optical waveguide film on which a 45 ° optical path conversion mirror surface is formed. In Patent Documents 1 and 2, after creating an optical waveguide in which an upper clad layer and a lower clad layer are formed above and below the core layer, a blade having a tip angle of 45 ° is used to face the core layer from the upper clad layer side. Cutting to form a mirror surface.

However, in the mirror surface forming methods disclosed in Patent Documents 1 and 2, since the upper clad layer is cut together with the core layer, the groove is exposed outside.
To solve this problem, at the stage where the lower clad layer and core layer before the upper clad layer are laminated, cutting is performed to form a mirror surface, and a metal film is deposited on the reflective surface of the core layer A method of laminating an upper clad layer after forming by the above method is conceivable.

JP 2006-011210 A JP 2006-017885 A

  However, when cutting is performed on an optical waveguide in which the upper clad layer is not laminated, burrs (cutting scraps) made of a resin of the cut optical waveguide material adhere to the edge of the optical waveguide. If the upper clad layer is laminated while the burrs are generated, the adhesiveness with the core layer and the lower clad layer is inferior, and the optical propagation loss value of the obtained optical waveguide may be increased.

  In view of the above problems, the present invention can reduce burrs generated at the edge of an optical waveguide when a groove is formed by cutting an optical waveguide in which at least a clat layer and a core layer are laminated in the form of a clat layer. It is an object of the present invention to provide a method for manufacturing a grooved optical waveguide, an optical waveguide obtained by the manufacturing method, and an optoelectric composite substrate including the optical waveguide.

The present inventors have found that the above-described problems can be solved through a specific cutting process.
That is, the present invention provides the following [1] to [3].
[1] Form a groove by cutting the core layer and the clad layer with respect to an optical waveguide in which at least a clad layer and a core layer are laminated on the clad layer using a cutting device having a circular rotating blade A method for manufacturing a grooved optical waveguide, wherein the tip of the cutting blade of the circular rotary blade is lowered to the boundary surface between the core layer and the cladding layer or to a position closer to the core layer than the boundary surface, and from the core layer side to the core layer And a second step of cutting the core layer and the clad layer from the core layer side by lowering the tip of the cutting blade of the circular rotary blade to a position lowered by 7 to 18 μm from the boundary surface to the clad layer side. And a method for producing a grooved optical waveguide.
[2] A grooved optical waveguide obtained by the manufacturing method according to [1] above.
[3] An optoelectric composite substrate comprising the grooved optical waveguide according to the above [2] and an electric wiring board on the substrate surface.

  According to the method for manufacturing a grooved optical waveguide of the present invention, it is possible to suppress the generation of burrs when a groove is formed by cutting an optical waveguide obtained by laminating a clat layer and a core layer in the form of a clat layer.

It is a schematic diagram which shows an example of the manufacturing method of the optical waveguide with a groove | channel of this invention. It is the figure which showed an example of the circular rotary blade used with the manufacturing method of the optical waveguide with a groove | channel of this invention, and is sectional drawing of the radial direction of the said circular rotary blade.

[Configuration of optical waveguide]
First, the optical waveguide of the present invention will be described with reference to FIG. The grooved optical waveguide 1 obtained by the manufacturing method of the present invention may be formed on a substrate 11 such as a flexible printed wiring board as shown in FIG. In FIG. 1C, a clad layer 12 is laminated on the substrate 11, and a core layer 13 is laminated thereon. The core layer 13 is preferably subjected to an exposure process to form a core pattern. The core layer 13 includes a case where a core pattern is formed.
Further, when the adhesion between the substrate 11 and the clad layer 12 is weak, an adhesive layer may be provided between the substrate 11 and the clad layer 12 as necessary. Details of these layers will be described later.

  Further, in the grooved optical waveguide 1, the core layer 13 and the clad layer 12 are cut, and a groove 16 including two cutting surfaces 15 a and 15 b is formed. In FIG. 1C, the shape of the groove 16 is V-shaped, but the shape of the groove can be appropriately set according to the application. When the groove shape is V-shaped, the inclination angles θ and δ of the two cutting surfaces 15a and 15b constituting the groove with respect to the horizontal surface of the cladding layer 12 or the core layer 13 can be appropriately set according to the application. . For example, when the two cutting surfaces are mirror surfaces, the respective inclination angles θ and δ are preferably 30 to 60 °, more preferably 40 to 50 °, and still more preferably 44 to 46 °. The inclination angles θ and δ may be the same or different from each other.

  In addition, the grooved optical waveguide 1 illustrated in FIG. 1C may be formed by depositing a metal such as gold or aluminum on the cut surfaces 15a and 15b after the cutting process. Further, if necessary, an upper clad layer is laminated on the core layer 13 (on the core layer 13 and the clad layer 12 when the core layer 13 forms a core pattern), and the groove 16 is exposed to the outside. You can also avoid it.

[Production method of grooved optical waveguide]
Next, the manufacturing method of the optical waveguide with a groove | channel of this invention is demonstrated using FIG.
In FIG. 1A, a clad layer 12 is laminated on a substrate 11, and a core layer 13 is laminated thereon to obtain an optical waveguide 2 before cutting. In the present invention, the method for producing the pre-cutting optical waveguide 2 is not particularly limited, and examples thereof include the methods described in the examples. The core layer 13 is preferably subjected to an exposure process to form a core pattern. Moreover, when the adhesiveness of the board | substrate 11 and the clad layer 12 is bad, you may adhere | attach the board | substrate 11 and the clad layer 12 through an adhesive layer as needed.

<First step>
As a first step, as shown in FIG. 1 (a), the circular rotating blade of the cutting device is moved to the boundary surface 14 between the core layer 13 and the cladding layer 12 or to the position closer to the core layer 13 than the boundary surface 14. The cutting edge tip 21 of 20 is lowered, and the core layer 13 is cut from the core layer 13 side.
The specific position of the cutting blade tip 21 is preferably the boundary surface 14 or a position on the core layer 13 side from the boundary surface 14, preferably a position on the −10 to 10 μm, more preferably a position on the −5 to 5 μm. Can be mentioned.

  Although it does not specifically limit as the circular rotary blade 20 used for cutting, A blade provided with a cutting blade without any deviation on the outer circumference, a blade provided with a saw-like cutting edge, a plurality of cutting blade portions and non-cutting parts on the outer circumference Examples thereof include a blade having alternating blade portions. In addition, the shape of the cutting blade tip 21 in the radial cross section of the circular rotating blade 20 is appropriately set according to the use of the obtained grooved optical waveguide, but when producing an optical waveguide having two mirror surfaces The V-shape is preferred. FIG. 2 shows the shape of the cutting blade tip 21 in the radial cross section of the circular rotating blade, where l indicates the horizontal plane of the core layer 13 or the cladding layer 12, and α and β are the horizontal plane of the core layer or the cladding layer. The tip angle is shown. The tip angle is preferably 30 to 60 degrees, more preferably 40 to 50 degrees, and still more preferably 44 to 46 degrees. The tip angles α and β may be the same as or different from each other.

The roughness of the circular rotating blade is equivalent to JIS standard for a blade using resin abrasive grains, preferably 1000 to 3000, more preferably 1500 to 1700, and equivalent to JIS standard for a blade using diamond abrasive grains. The number is preferably 3000 to 7000, more preferably 3000 to 4500. If the circular rotary blade is too rough, the cut surface of the cut becomes rough and scatters the propagation light. On the other hand, if the roughness of the blade is too fine, the blade is likely to be clogged, and the optical waveguide 2 before cutting may be peeled off from the substrate 11.
Although the thickness of a circular rotary blade is suitably set according to a use, Preferably it is 100 micrometers or more, More preferably, it is 140-280 micrometers.
The diameter of the circular rotary blade 50 is preferably 50 to 58 mm, more preferably 50 to 54 mm, and still more preferably 51 to 52 mm in a 2-inch blade compatible device, depending on the specifications of the device.

The rotational speed of the circular rotary blade is preferably 25,000 to 35,000 rpm, more preferably 27,000 to 33,000 rpm, from the viewpoint of making the cutting surface smooth.
The feeding speed of the circular rotary blade is preferably 1 mm / s to 10 mm / s, more preferably 1 mm / s to 5 mm / s. The feed rate in this range is about 1/10 of the feed rate of the blade when manufacturing the semiconductor element. By cutting the core layer 13 and the cladding layer 12 at such a slow feed rate, the cut surface can be formed into a smooth surface.
In cutting, it is preferable to supply blade cooler water at about 1.0 to 2.0 L / min and shower water at about 0.5 to 2.0 L / min in order to suppress heat generation.
In addition, the cutting may be any of upward cutting (up cut) and downward cutting (down cut).

<Second step>
As the second step, as shown in FIG. 1B, the cutting blade tip 21 of the circular rotary blade 20 is lowered from the boundary surface 14 to a position lowered by 7 to 18 μm toward the cladding layer 12, and from the core layer 13 side. The core layer 13 and the clad layer 12 are cut.
In FIG. 1B, L1 indicates a distance by which the cutting blade tip 21 is lowered from the boundary surface 14 to the cladding layer 12 side. In this step, L1 is 7 to 18 μm. If it is less than 7 μm and larger than 18 μm, the burrs (cut scraps) made of the resin of the cut optical waveguide material adhere to the edge of the optical waveguide, which leads to reduction of light propagation loss and the like. From this viewpoint, L1 is preferably 5 to 15 μm, more preferably 7 to 13 μm, and still more preferably 8 to 12 μm.
Moreover, the circular rotary blade 20 used in the cutting in this step can use the circular rotary blade in the first step described above, and the cutting process conditions are the same as those in the first step.

  Through the first step and the second step, the grooved optical waveguide 1 shown in FIG. 1C is obtained. Thereafter, a metal such as gold or copper may be vapor-deposited on the cutting surfaces 15a and 15b serving as mirror surfaces of the groove 16. Further, a clad layer may be further laminated as an upper clad layer on the core layer 13 (on the core layer 13 and the clad layer 12 when the core layer 13 forms a core pattern).

<About each configuration of optical waveguide with groove>
Hereinafter, each component of the optical waveguide of the present invention will be described.
(substrate)
The optical waveguide of the present invention can be formed on a substrate. The type of the substrate is not particularly limited, but the dimensional stability of the optical waveguide itself can be imparted by using a non-flexible substrate having a dimensional stability and thickness. The material of the substrate having a dimensional stability and thickness is not particularly limited, but from the viewpoint of dimensional stability, a flexible printed wiring board, an FR-4 substrate, a semiconductor substrate, a silicon plate, a glass plate, a metal plate, or the like is preferable. Can be mentioned. Removability from the optical waveguide can be imparted by subjecting the above-described dimensional-stable and thick non-flexible material to a release treatment. The thickness of the substrate may be appropriately changed depending on the warp and dimensional stability of the plate, but is preferably 0.1 to 10.0 mm.

Further, in order to give the substrate releasability from the optical waveguide, a film having a flat surface may be attached to the inflexible substrate. The material of the film is not particularly limited, but from the viewpoint of having toughness, polyesters such as polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polyethylene, polypropylene, polyamide, polycarbonate, polyphenylene ether, polyether sulfide, poly Examples include arylate, liquid crystal polymer, polysulfone, polyethersulfone, polyetheretherketone, polyetherimide, polyamideimide, and polyimide. From the viewpoints of removability and heat resistance, polyimide and aramid are preferably used as the film material. The thickness of the film may be appropriately changed depending on the intended flexibility, but is preferably 5 to 250 μm.

For adhesion between the substrate and the cladding layer of the optical waveguide, an adhesive layer made of a removable adhesive or adhesive film may be provided. However, it is not necessary to use an adhesive or an adhesive film when the substrate has removability. Preferable examples of the material for the adhesive or the adhesive film include single-sided slightly double-sided tape, hot-melt adhesive, UV or heat-peelable adhesive.
In addition, re-peeling such as when bonding a non-flexible material and a film having releasability to an optical waveguide or when it is necessary to use an adhesive because the clad layer or substrate has no adhesive force For adhesion without requiring heat resistance, a heat-resistant adhesive or adhesive film is preferable. Although it does not specifically limit as a material of the adhesive agent or adhesive film used when it is not necessary to peel again, From a heat resistant viewpoint, a prepreg, a buildup material, a heat resistant adhesive agent etc. are mentioned suitably.
Although the thickness of an adhesive bond layer and an adhesive film is not specifically limited, Preferably they are 5 micrometers-3.0 mm. When bonding a board | substrate and an optical waveguide on both sides of the said release sheet, it is preferable that the thickness of an adhesive bond layer and an adhesive film is 5 micrometers or more thicker than a release sheet.

(Clad layer)
As the cladding layer, a cladding layer forming resin or a cladding layer forming resin film can be used.
The resin for forming the cladding layer is not particularly limited as long as it is a resin composition that has a lower refractive index than the core layer and is cured by light or heat, and a thermosetting resin composition or a photosensitive resin composition is preferably used. be able to. More preferably, the clad layer forming resin is preferably composed of a resin composition containing (A) a base polymer, (B) a photopolymerizable compound, and (C) a photopolymerization initiator. When the upper cladding layer is further formed, the components contained in the resin composition of the upper cladding layer may be the same as or different from those of the lower cladding layer, and the refractive index of the resin composition is the same. Or different.

  (A) The base polymer is for forming a clad layer and ensuring the strength of the clad layer, and is not particularly limited as long as the object can be achieved. Phenoxy resin, epoxy resin, (meth) Examples thereof include acrylic resins, polycarbonate resins, polyarylate resins, polyether amides, polyether imides, polyether sulfones, and derivatives thereof. These base polymers may be used alone or in combination of two or more. Of the base polymers exemplified above, from the viewpoint of high heat resistance, the main chain preferably has an aromatic skeleton, and particularly preferably a phenoxy resin. From the viewpoint of three-dimensional crosslinking and improving heat resistance, an epoxy resin, particularly an epoxy resin that is solid at room temperature is preferable. Further, compatibility with the photopolymerizable compound (B) described in detail later is important for ensuring the transparency of the resin for forming the cladding layer. From this point, the phenoxy resin and the (meth) acrylic resin are used. Is preferred. Here, (meth) acrylic resin means acrylic resin and methacrylic resin.

  Among phenoxy resins, those containing bisphenol A, bisphenol A type epoxy compounds or derivatives thereof, and bisphenol F, bisphenol F type epoxy compounds or derivatives thereof as a constituent unit of the copolymer component are heat resistant, adhesive and soluble. It is preferable because of its excellent properties. Preferred examples of the bisphenol A or bisphenol A type epoxy compound include tetrabromobisphenol A and tetrabromobisphenol A type epoxy compounds. Moreover, as a derivative of bisphenol F or a bisphenol F-type epoxy compound, tetrabromobisphenol F, a tetrabromobisphenol F-type epoxy compound, etc. are mentioned suitably. Specific examples of the bisphenol A / bisphenol F copolymer type phenoxy resin include “Phenotote YP-70” (trade name) manufactured by Toto Kasei Co., Ltd.

  Examples of the epoxy resin that is solid at room temperature include, for example, “Epototo YD-7020, Epototo YD-7019, Epototo YD-7007” (all trade names) manufactured by Toto Chemical Co., Ltd., and “Epicoat 1010” manufactured by Japan Epoxy Resins Co., Ltd. Bisphenol A type epoxy resin such as “Epicoat 1009, Epicoat 1008” (both are trade names).

(B) The photopolymerizable compound is not particularly limited as long as it is polymerized by irradiation with light such as ultraviolet rays, and a compound having an ethylenically unsaturated group in the molecule or two or more epoxy groups in the molecule. And the like.
Examples of the compound having an ethylenically unsaturated group in the molecule include (meth) acrylate, vinylidene halide, vinyl ether, vinyl pyridine, vinyl phenol, etc., among these, from the viewpoint of transparency and heat resistance, (Meth) acrylate is preferred.
As the (meth) acrylate, any of monofunctional, bifunctional, trifunctional or higher polyfunctional ones can be used. Here, (meth) acrylate means acrylate and methacrylate.
Examples of the compound having two or more epoxy groups in the molecule include bifunctional or polyfunctional aromatic glycidyl ethers such as bisphenol A type epoxy resins, bifunctional or polyfunctional aliphatic glycidyl ethers such as polyethylene glycol type epoxy resins, and water. Bifunctional alicyclic glycidyl ether such as bisphenol A type epoxy resin, bifunctional aromatic glycidyl ester such as diglycidyl phthalate, bifunctional alicyclic glycidyl ester such as tetrahydrophthalic acid diglycidyl ester, N, N- Bifunctional or polyfunctional aromatic glycidylamine such as diglycidylaniline, bifunctional alicyclic epoxy resin such as alicyclic diepoxycarboxylate, bifunctional heterocyclic epoxy resin, polyfunctional heterocyclic epoxy resin, bifunctional Or polyfunctional silicon-containing epoxy resin It is. These (B) photopolymerizable compounds can be used alone or in combination of two or more.

  There is no restriction | limiting in particular as a photoinitiator of (C) component, For example, as an initiator in the case of using an epoxy compound for (B) component, aryl diazonium salt, diaryl iodonium salt, triaryl sulfonium salt, triallyl selenonium A salt, a dialkylphenazylsulfonium salt, a dialkyl-4-hydroxyphenylsulfonium salt, a sulfonic acid ester, and the like.

Moreover, as an initiator in the case of using a compound having an ethylenically unsaturated group in the molecule as the component (B), aromatic ketones such as benzophenone, quinones such as 2-ethylanthraquinone, benzoin ethers such as benzoin methyl ether Compounds, benzoin compounds such as benzoin, benzyl derivatives such as benzyldimethyl ketal, 2,4,5-triarylimidazole dimers such as 2- (o-chlorophenyl) -4,5-diphenylimidazole dimer, 2- Benzimidazoles such as mercaptobenzimidazole, phosphine oxides such as bis (2,4,6-trimethylbenzoyl) phenylphosphine oxide, acridine derivatives such as 9-phenylacridine, N-phenylglycine, N-phenylglycine derivatives , Coumarin compound Etc. The. Moreover, you may combine a thioxanthone type compound and a tertiary amine compound like the combination of diethyl thioxanthone and dimethylaminobenzoic acid. Of these compounds, aromatic ketones and phosphine oxides are preferred from the viewpoint of improving the transparency of the core layer and the cladding layer.
These (C) photopolymerization initiators can be used alone or in combination of two or more.

(A) It is preferable that the compounding quantity of a base polymer shall be 5-80 mass% with respect to the total amount of (A) component and (B) component. Moreover, it is preferable that the compounding quantity of (B) photopolymerizable compound shall be 95-20 mass% with respect to the total amount of (A) and (B) component.
As a blending amount of the component (A) and the component (B), when the component (A) is 5% by mass or more and the component (B) is 95% by mass or less, the resin composition is easily formed into a film. Can do. On the other hand, when the component (A) is 80% by mass or less and the component (B) is 20% by mass or more, the (A) base polymer can be easily entangled and cured, and an optical waveguide is formed. The pattern forming property is improved and the photocuring reaction proceeds sufficiently. From the above viewpoint, the blending amount of the component (A) and the component (B) is more preferably 10 to 85% by mass of the component (A) and 90 to 15% by mass of the component (B), and the component 20 to 70 More preferably, the content is 80% by mass and (B) component 80-30% by mass.
(C) It is preferable that the compounding quantity of a photoinitiator shall be 0.1-10 mass parts with respect to 100 mass parts of total amounts of (A) component and (B) component. When the blending amount is 0.1 parts by mass or more, the photosensitivity is sufficient, while when it is 10 parts by mass or less, the absorption in the surface layer of the photosensitive resin composition does not increase during exposure, and the internal Is sufficiently cured. Further, when used as an optical waveguide, it is preferable that the propagation loss does not increase due to the light absorption effect of the polymerization initiator itself. From the above viewpoint, the blending amount of the (C) photopolymerization initiator is more preferably 0.2 to 5 parts by mass.
In addition, if necessary, in the cladding layer forming resin, an antioxidant, an anti-yellowing agent, an ultraviolet absorber, a visible light absorber, a colorant, a plasticizer, a stabilizer, a filler, etc. You may add what is called an additive in the ratio which does not have a bad influence on the effect of this invention.

In the present invention, the method for forming the clad layer is not particularly limited, and for example, the clad layer may be formed by applying a clad layer forming resin or laminating a clad layer forming resin film.
In the case of application, the method is not limited. For example, the resin composition containing the components (A) to (C) may be applied by a conventional method.
Moreover, the resin film for clad layer formation used for a lamination can be easily manufactured by melt | dissolving the said resin composition in a solvent, apply | coating it to a support body film, and removing a solvent, for example.

The support film used in the production process of the resin film for forming a clad layer is not particularly limited with respect to the material thereof, and various films can be used. From the viewpoints of flexibility and toughness as the support film, those exemplified above as the film material that can be used for the substrate can be similarly mentioned.
The thickness of the support film may be appropriately changed depending on the intended flexibility, but is preferably 5 to 250 μm. If it is 5 μm or more, there is an advantage that toughness is easily obtained, and if it is 250 μm or less, sufficient flexibility can be obtained.
The solvent used here is not particularly limited as long as it can dissolve the resin composition. For example, acetone, methyl ethyl ketone, methyl cellosolve, ethyl cellosolve, toluene, N, N-dimethylacetamide, propylene glycol monomethyl ether, propylene A solvent such as glycol monomethyl ether acetate, cyclohexanone, N-methyl-2-pyrrolidone, or a mixed solvent thereof can be used. The solid content concentration in the resin solution is preferably about 30 to 80% by mass.

Regarding the thickness of the cladding layer, the thickness after drying is preferably in the range of 5 to 500 μm. When the thickness is 5 μm or more, a clad thickness necessary for light confinement can be secured, and when the thickness is 500 μm or less, it is easy to control the film thickness uniformly. From the above viewpoint, the thickness of the cladding layer is more preferably in the range of 10 to 100 μm.
When the upper clad layer is formed, the thickness of the upper clad layer may be the same as or different from that of the lower clad layer. It is preferable to make it thicker than the thickness of the layer.

(Core layer forming resin and core layer forming resin film)
In the present invention, the method for forming the core layer laminated on the clad layer is not particularly limited. For example, the core layer may be formed by applying a core layer forming resin or laminating a core layer forming resin film.
As the resin for forming the core layer, a resin composition that is designed to have a higher refractive index than that of the cladding layer and can form the core layer with actinic rays can be used, and a photosensitive resin composition is preferable. Specifically, it is preferable to use the same resin composition as that used in the clad layer forming resin.
In the case of application, the method is not limited, and the resin composition may be applied by a conventional method.

Hereinafter, the resin film for core layer formation used for lamination is explained in full detail.
The resin film for forming the core layer can be easily produced by dissolving the resin composition in a solvent, applying the resin composition on the cladding layer, and removing the solvent. The solvent used here is not particularly limited as long as it can dissolve the resin composition. For example, acetone, methyl ethyl ketone, methyl cellosolve, ethyl cellosolve, toluene, N, N-dimethylformamide, N, N-dimethyl A solvent such as acetamide, propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, cyclohexanone, N-methyl-2-pyrrolidone, or a mixed solvent thereof can be used. It is preferable that the solid content concentration in the resin solution is usually 30 to 80% by mass.

  The thickness of the resin film for forming the core layer is not particularly limited, and the thickness of the core layer after drying is usually adjusted to be 10 to 100 μm. If the thickness of the film is 10 μm or more, there is an advantage that the alignment tolerance can be increased in the coupling with the light emitting / receiving element or the optical fiber after the optical waveguide is formed. In coupling with an element or an optical fiber, there is an advantage that coupling efficiency is improved. From the above viewpoint, the thickness of the film is preferably in the range of 30 to 70 μm.

The support film used in the production process of the core layer forming resin is a support film that supports the core layer forming resin, and the material thereof is not particularly limited, but the core layer forming resin may be peeled later. From the viewpoint of being easy and having heat resistance and solvent resistance, polyesters such as polyethylene terephthalate, polypropylene, polyethylene and the like are preferable.
The thickness of the support film is preferably 5 to 50 μm. When it is 5 μm or more, there is an advantage that the strength as a support film is easily obtained, and when it is 50 μm or less, there is an advantage that a gap with the mask at the time of pattern formation becomes small and a finer pattern can be formed. From the above viewpoint, the thickness of the support film is more preferably in the range of 10 to 40 μm, and particularly preferably 15 to 30 μm.
The optical waveguide used in the present invention may be a multilayer optical waveguide in which a plurality of polymer layers having a core layer and a cladding layer are stacked.

[Photoelectric composite substrate]
The grooved optical waveguide obtained by the manufacturing method of the present invention can be a photoelectric composite substrate having the optical waveguide and an electric wiring board on the substrate surface.
The electrical wiring board is not particularly limited, and various electrical wiring boards used for the photoelectric composite member can be used, for example, a flexible printed wiring board in which wiring is directly provided on the substrate, A polyimide substrate having copper bonded on one side may be used, and an electrical wiring pattern may be formed after bonding with the optical waveguide. Furthermore, the above wiring board may be multilayered.
The optoelectric composite substrate having the grooved optical waveguide of the present invention can be an optoelectronic composite module that can be applied to various fields of optical interconnection. Examples of the photoelectric composite module using the optical waveguide of the present invention include an AOC (active optical cable).

[Production example]
Each step was performed as follows, and an optical waveguide before cutting was produced.
(1) Production of resin film for forming clad layer (A) As a base polymer, 48 parts by mass of phenoxy resin (trade name: Phenotote YP-70, manufactured by Tohto Kasei Co., Ltd.), (B) as a photopolymerizable compound, 49.6 parts by mass of alicyclic diepoxycarboxylate (trade name: KRM-2110, molecular weight: 252, manufactured by Asahi Denka Kogyo Co., Ltd.), (C) triphenylsulfonium hexafluoroantimonate salt as a photopolymerization initiator (Product name: SP-170, manufactured by Asahi Denka Kogyo Co., Ltd.) 2 parts by weight, 40 parts by weight of propylene glycol monomethyl ether acetate as an organic solvent are weighed into a wide-mouthed plastic bottle, using a mechanical stirrer, shaft and propeller, The mixture was stirred for 6 hours under the conditions of a temperature of 25 ° C. and a rotation speed of 400 rpm to prepare a clad layer forming resin varnish. After that, using a polyfluorone filter (trade name: PF020, manufactured by Advantech Toyo Co., Ltd.) with a pore size of 2 μm, it is filtered under pressure at a temperature of 25 ° C. and a pressure of 0.4 MPa, and further reduced in pressure using a vacuum pump and a bell jar. Degassed under reduced pressure for 15 minutes under the condition of 50 mmHg.
The resin varnish for forming a clad layer obtained above was coated on a non-treated surface of a PET film (trade name: Cosmo Shine A4100, manufactured by Toyobo Co., Ltd., thickness: 50 μm) (Multicoater TM-MC , Manufactured by Hirano Tech Seed Co., Ltd.), dried at 80 ° C. for 10 minutes, then at 100 ° C. for 10 minutes, and then released as a protective film PET film (trade name: Purex A31, Teijin DuPont Films Ltd.) , Thickness: 25 μm) was pasted so that the release surface was on the resin side, and a resin film for forming a clad layer was obtained. At this time, the thickness of the resin layer can be arbitrarily adjusted by adjusting the gap of the coating machine. In this example, the thickness after curing was adjusted to 25 μm.

(2) Production of core layer-forming resin film (A) As a base polymer, 26 parts by mass of phenoxy resin (trade name: Phenototo YP-70, manufactured by Tohto Kasei Co., Ltd.), (B) as a photopolymerizable compound, 9,9-bis [4- (2-acryloyloxyethoxy) phenyl] fluorene (trade name: A-BPEF, manufactured by Shin-Nakamura Chemical Co., Ltd.) 36 parts by mass, and bisphenol A type epoxy acrylate (trade name: EA -1020, Shin-Nakamura Chemical Co., Ltd.) 36 parts by mass, (C) As a photopolymerization initiator, bis (2,4,6-trimethylbenzoyl) phenylphosphine oxide (trade name: Irgacure 819, Ciba Specialty) -1 part by mass of Chemicals Co., Ltd.) and 1- [4- (2-hydroxyethoxy) phenyl] -2-hydroxy-2-methyl-1 -Propan-1-one (trade name: Irgacure 2959, manufactured by Ciba Specialty Chemicals) 1 part by weight, except that 40 parts by weight of propylene glycol monomethyl ether acetate was used as the organic solvent, the above resin film for forming a cladding layer After preparing the core layer-forming resin varnish by the same method and conditions as in the preparation example, pressure filtration and degassing under reduced pressure were performed.
The core layer-forming resin varnish obtained above is applied to the non-treated surface of a PET film (trade name: Cosmo Shine A1517, manufactured by Toyobo Co., Ltd., thickness: 16 μm) in the same manner as in the above production example. After coating and drying, a release PET film (trade name: A31, Teijin DuPont Films Co., Ltd., thickness: 25 μm) is attached as a protective film so that the release surface is on the resin side, and a resin film for forming a core layer Got. In this example, the gap of the coating machine was adjusted so that the film thickness after curing was 50 μm.

  When the refractive index of the core layer and the clad layer was measured with a prism coupler (Model 2010) manufactured by Metricon, the core layer was 1.584 and the clad layer was 1.550 at a wavelength of 830 nm.

(3) Production of adhesive film An adhesive film described in Example 1 of PCT / JP2008 / 05465 was produced. That is, (a) YDCN-703 (trade name, manufactured by Toto Kasei Co., Ltd., cresol novolac type epoxy resin, epoxy equivalent 210) 55 parts by mass as an epoxy resin, (b) Millex XLC-LL (Mitsui Chemicals, Inc.) as a curing agent Product name, phenol resin, hydroxyl group equivalent 175, water absorption rate 1.8% by mass, heating weight reduction rate 4% at 350 ° C. 45% by mass, silane coupling agent NUC A-189 (trade name, manufactured by Nihon Unicar Co., Ltd.) 1.7 parts by weight of γ-mercaptopropyltrimethoxysilane) and 3.2 parts by weight of NUC A-1160 (trade name, γ-ureidopropyltriethoxysilane manufactured by Nihon Unicar Co., Ltd.), (d) Aerosil R972 (silica) as filler The surface is coated with dimethyldichlorosilane and hydrolyzed in a 400 ° C reactor. , A filler having an organic group such as a methyl group on its surface, a product name made by Nippon Aerosil Co., Ltd., silica, an average particle size of 0.016 μm), 32 parts by mass, cyclohexanone is added to the mixture and stirred, And kneaded for 90 minutes. 280 parts by mass of (c) acrylic rubber HTR-860P-3 (trade name, weight average molecular weight of 800,000 manufactured by Nagase ChemteX Corporation) containing 3% by mass of glycidyl acrylate or glycidyl methacrylate as a polymer compound, and (e ) Curazole 2PZ-CN (trade name, 1-cyanoethyl-2-phenylimidazole manufactured by Shikoku Kasei Kogyo Co., Ltd.) as a curing accelerator was added in an amount of 0.5 parts by mass, stirred and mixed, and vacuum degassed. This adhesive varnish was applied onto a 75 μm-thick polyethylene terephthalate (PET) film (Purex A31) subjected to a release treatment, and heated and dried at 140 ° C. for 5 minutes to form a coating film having a thickness of 10 μm. Next, a 25 μm release-treated polyethylene terephthalate (PET) film (Purex A31) was attached as a second protective film so that the release surface was on the resin side to obtain an adhesive film.

(4) Preparation of optical waveguide before cutting processing A flexible printed wiring board on which a desired copper wiring circuit is formed is used as a substrate, and an adhesive surface of the adhesive film is formed on the wiring board by a roll laminator (Hitachi Chemical Technoplant). Lamination was performed under the conditions of a pressure of 0.4 MPa, a temperature of 50 ° C., and a laminating speed of 0.2 m / min. Thereafter, ultraviolet light (wavelength 365 nm) is irradiated at 1 J / cm ² from the adhesive film side with an ultraviolet exposure machine (EXM-1172, manufactured by Oak Manufacturing Co., Ltd.), and a release PET film (Purex) which is a protective film from the adhesive film. A31) was peeled off, and then a polyimide film (Espanex SC35, thickness: 35 μm) was attached under the same laminating conditions as above to obtain a substrate 11.

The release PET film (Purex A31), which is a protective film for the resin film for forming a clad layer obtained above, is peeled off, and the vacuum pressure laminator is attached to the side of the substrate 11 obtained above where the adhesive layer is attached. (MLP Co., Ltd., MVLP-500) was used to evacuate to 500 Pa or less, and then thermocompression bonded under conditions of a pressure of 0.4 MPa, a temperature of 50 ° C., and a pressurization time of 30 seconds, and an ultraviolet exposure machine ( The cladding layer 12 was formed by irradiating 1.5 J / cm ^{2 of} ultraviolet rays (wavelength 365 nm) from the resin side with Oak Mfg. Co., Ltd. (EXM-1172), followed by heat treatment at 80 ° C. for 10 minutes.

Next, the above core layer is formed on the clad layer 12 using a roll laminator (HLM-1500, manufactured by Hitachi Chemical Technoplant Co., Ltd.) under conditions of a pressure of 0.4 MPa, a temperature of 50 ° C., and a laminating speed of 0.2 m / min. After laminating a resin film for a plate, and then vacuuming to 500 Pa or less using a vacuum pressure laminator (MVLP-500 manufactured by Meiki Seisakusho Co., Ltd.) as a flat plate laminator, pressure 0.4 MPa, temperature 50 ° C., pressure The core layer 13 was formed by thermocompression bonding under conditions of time 30 seconds.
Then, through a negative photomask having a width of 50 μm, ultraviolet rays (wavelength 365 nm) were irradiated with 0.8 J / cm ² with the above-described ultraviolet exposure machine, followed by heating after exposure at 80 ° C. for 5 minutes. Thereafter, the PET film as the support film was peeled off, and the core pattern was developed from the core layer 13 using a developer (propylene glycol monomethyl ether acetate / N, N-dimethylacetamide = 7/3, mass ratio). Then, it wash | cleaned using the washing | cleaning liquid (isopropanol), and heat-dried at 100 degreeC for 10 minute (s), and produced the optical waveguide 2 before a cutting process.

[Example 1]
Using the pre-cutting optical waveguide obtained by the above manufacturing example, cutting was performed as follows. The circular rotary blade used has a V-shaped cross section in the radial direction as shown in FIG. 2 and is manufactured by Disco Corporation (both tip angles α and β in FIG. 2 are 45 °, particle size; # 5000, outer diameter 51 mm, inner diameter; 40 mm, thickness; 240 μm).
First, as a first step, the cutting blade tip 21 of the circular rotating blade 20 is lowered to the boundary surface 14 between the core layer 13 and the clad layer 12, and the rotational speed of the circular rotating blade is 30,000 rpm and the feed rate is 1.0 mm / second. Under the above conditions, the core layer 13 was cut while performing a down cut while supplying blade cooler water at about 0.5 L / min and shower water at about 1.0 L / min.
Next, as a second step, the cutting blade tip 21 of the circular rotary blade 20 is lowered to a position 10 μm lower than the boundary surface 14, and the core layer 13 and the cladding layer 12 are cut under the same conditions as in the first step. Then, a V-shaped groove 16 composed of two cutting surfaces 15a and 15b was formed to obtain a grooved optical waveguide.

[Comparative Examples 1-3]
In Comparative Example 1, a grooved optical waveguide was obtained by cutting in the same manner as in Example 1 except that the first step was not performed.
In Comparative Examples 2 and 3, cutting was performed in the same manner as in Example 1 except that the position where the cutting edge tip 21 of the circular rotating blade 20 was lowered from the boundary surface 14 in the second step was changed as shown in Table 1. A grooved optical waveguide was obtained.

  Table 1 shows whether or not burrs are generated in the optical waveguide obtained as described above. As shown in Table 1, the grooved optical waveguide of Example 1 was good with no burrs. On the other hand, generation of burrs was observed in Comparative Examples 1 to 3.

  The grooved optical waveguide of the present invention can be a member of a photoelectric composite module that can be applied to various optical interconnection fields.

1; grooved optical waveguide 2; pre-cutting optical waveguide 11; substrate 12; (lower) clad layer 13; core layer (core pattern)
14; boundary surfaces 15a and 15b; cutting surface 16; groove 20; circular rotary blade 21; cutting blade tip

Claims (3)

With a groove for forming a groove by cutting the core layer and the clad layer using a cutting device equipped with a circular rotating blade for an optical waveguide having at least a clad layer and a core layer laminated on the clad layer An optical waveguide manufacturing method comprising:
A first step of lowering the cutting edge of the circular rotary blade to a boundary surface between the core layer and the cladding layer or a position closer to the core layer than the boundary surface, and cutting the core layer from the core layer side;
A second step of lowering the cutting blade tip of the circular rotary blade from the boundary surface to a position lowered by 7 to 18 μm from the boundary surface to the cladding layer side, and cutting the core layer and the cladding layer from the core layer side, and
A method of manufacturing a grooved optical waveguide , wherein the groove formed in the optical waveguide is a V-shaped groove formed of two cutting surfaces inclined by 30 to 60 ° with respect to a horizontal plane of the cladding layer or the core layer . With a groove for forming a groove by cutting the core layer and the clad layer using a cutting device equipped with a circular rotating blade for an optical waveguide having at least a clad layer and a core layer laminated on the clad layer An optical waveguide manufacturing method comprising:
A first step of lowering the cutting edge of the circular rotary blade to a boundary surface between the core layer and the cladding layer or a position closer to the core layer than the boundary surface, and cutting the core layer from the core layer side;
A second step of lowering the cutting blade tip of the circular rotary blade from the boundary surface to a position lowered by 7 to 18 μm from the boundary surface to the cladding layer side, and cutting the core layer and the cladding layer from the core layer side, and
A method for manufacturing a grooved optical waveguide , wherein a shape of a tip of the cutting blade in a radial cross section of the circular rotary blade is a V-shape in which a tip angle of the core layer or the cladding layer with respect to a horizontal plane is inclined by 30 to 60 °. . The manufacturing method of the optical waveguide with a groove | channel of Claim 1 or 2 whose rotation speed of the said circular rotary blade is 25,000-35,000rpm.

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