JP2013142828A - Optical waveguide and method for manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical waveguide with a mirror which can secure the flatness of a substrate and transmit a light signal regardless of the type of a substrate and also propagate a signal with low loss.SOLUTION: There is provided a method for manufacturing an optical waveguide, the method comprising the steps of: (A) providing a release layer on one surface of a substrate having at least one opening part, forming a transparent resin layer composed of a transparent resin on the other surface and filling the opening part with a transparent resin; (B) removing the release layer after filling the opening part with a transparent resin; (C) forming an optical waveguide composed of a core layer and a clad layer on the substrate; and (D) forming a mirror part on the core layer immediately above the opening part.

Description

  The present invention relates to a method for manufacturing an optical waveguide, and more particularly to a method for manufacturing an optical waveguide with a mirror.

  With the increase in information capacity, development of optical interconnection technology that uses optical signals not only for communication fields such as trunk lines and access systems but also for information processing in routers and servers is underway. In particular, as an optical transmission path for using light for short-distance signal transmission between boards in a router or a server device, optical fibers that have a higher degree of freedom in wiring and can be densified than optical fibers. It is desirable to use a waveguide. Among them, an optical waveguide using a polymer material excellent in processability and economy is promising.

As such an optical waveguide, for example, as described in Patent Document 1, first, after the lower cladding layer is cured and formed, a core pattern is formed on the lower cladding layer, and the upper cladding layer is laminated, An optical waveguide is formed. Thereafter, an optical waveguide in which a mirror portion is formed by cutting has been proposed.
In the case of such an optical waveguide, since the optical signal whose optical path has been changed by the mirror portion passes through the substrate, the substrate needs to be made of a material having a high transmittance with respect to the optical signal. Furthermore, when there is a space between the substrate and the optical element, the spot diameter of the optical signal whose optical path has been changed by the mirror portion becomes large, leading to deterioration in propagation loss.

In addition, as an optical waveguide in which a space is reduced between the substrate and the optical element, for example, as described in Patent Document 2, a hole is provided in the middle or at the end of the core, and the optical path is provided in the hole. An optical waveguide with a mirror in which a conversion component is inserted has been proposed.
However, in the case of such an optical waveguide, since it is necessary to insert an optical path conversion component for each optical path conversion portion of each optical waveguide, the work is complicated, and alignment in the substrate plane direction and the substrate vertical direction is performed. Because it was necessary, high-precision alignment was necessary.
Furthermore, if a support locking part for locking the light conversion component is provided at the opening edge in order to align the substrate in the vertical direction, the mirror part protrudes from the surface of the clad layer, and the optical component is mounted inside the connector. When it is combined with the optical element mounting substrate, the mounting is hindered.

JP 2006-011210 A JP-A-2005-70142

  The present invention has been made in order to solve the above-described problems, and can ensure the flatness of the substrate and can transmit an optical signal regardless of the type of the substrate. An object is to provide a method for manufacturing a waveguide.

As a result of intensive studies to solve the above problems, the present inventors have provided a release layer on one surface of the substrate, formed a transparent resin layer made of a transparent resin on the other surface, and formed the opening portion. It has been found that the above problem can be solved by a production method having a step of filling with a transparent resin. The present invention has been completed based on such knowledge.
That is, the present invention
The present invention provides the following inventions.
(1) (A) A release layer is provided on one surface of a substrate having at least one opening, a transparent resin layer made of a transparent resin is formed on the other surface, and the opening is filled with a transparent resin. (B) a step of removing the release layer after filling the opening with a transparent resin, (C) a step of forming an optical waveguide comprising a core layer and a cladding layer on the substrate, and (D) the step Forming a mirror portion in the core layer directly above the opening, and a method of manufacturing an optical waveguide,
(2) The method for manufacturing an optical waveguide according to (1), wherein the step (C) is a step of sequentially forming a lower clad layer, a core layer, and an upper clad layer on the substrate.
(3) The method for manufacturing an optical waveguide according to (1), wherein the step (C) is a step of sequentially forming a lower clad layer, a core layer, and an upper clad layer on the transparent resin layer,
(4) The method for producing an optical waveguide according to (1) or (2), wherein the transparent resin layer is a lower cladding layer or a core layer,
(5) The transparent resin is a photosensitive transparent resin, and further includes a step (E) of photocuring the transparent resin filling at least the opening from the transparent resin layer side after the step (A). A method for producing an optical waveguide according to any one of (1) to (4),
(6) The method for producing an optical waveguide according to (5), further comprising a step (F) of developing a surface opposite to the transparent resin layer forming surface after the step (B), and (7) the above (1) The optical waveguide manufactured by the method in any one of (6)-(6) is provided.

  According to the method for manufacturing an optical waveguide of the present invention, it is possible to obtain an optical waveguide that can ensure the flatness of the substrate and can transmit an optical signal regardless of the type of the substrate, and can propagate the signal with low loss.

It is a figure explaining an example of the manufacturing method of the optical waveguide of this invention. It is a figure explaining an example of the optical waveguide obtained by the manufacturing method of this invention. It is a figure explaining another example of the optical waveguide obtained by the manufacturing method of this invention. It is a figure explaining another example of the optical waveguide obtained by the manufacturing method of this invention.

The production method of the present invention includes the following steps (A) to (D).
(A) a step of providing a release layer on one surface on a substrate having at least one opening, forming a transparent resin layer made of a transparent resin on the other surface, and filling the opening with a transparent resin;
(B) removing the release layer after filling the opening with a transparent resin;
(C) forming an optical waveguide comprising a core layer and a clad layer on the substrate;
(D) A step of forming a mirror portion in the core layer immediately above the opening.
Hereinafter, each step will be described in detail with reference to FIG.

Step (A)
In the step (A), as shown in FIG. 1A, a release layer 4 is provided on one surface on a substrate 1 having at least one opening, and a transparent resin layer made of a transparent resin is provided on the other surface. 3 and filling the opening 2 with a transparent resin.
There are no particular restrictions on the method of laminating the transparent resin on the substrate 1 to form the transparent resin layer 3 and the method of filling the opening 2 with the transparent resin, but if the transparent resin is varnished, What is necessary is just to apply | coat by a conventional method. When the transparent resin is in the form of a film, various methods such as a roll laminator, a vacuum pressure laminator, a press, and a vacuum press may be used. At this time, the release layer 4 is provided on the surface of the substrate 1 opposite to the surface on which the transparent resin layer 3 is formed. As a result, the wraparound of the transparent resin flowing into the opening 2 can be reduced, and film loss due to the resin outflow of the transparent resin layer 3 to be formed and non-flatness can be suppressed.
In addition, between the release layer 4 and the board | substrate 1, what is necessary is just to have peelability (non-adhesiveness), and it is not necessary to have adhesiveness (including re-peelability).

  In the present invention, if the substrate 1 is exposed from the transparent resin layer 3 forming surface side instead of the light-shielding portion using a photocurable transparent resin, the inside of the opening 2 can be efficiently cured. For example, the release layer 4 Even when the transparent resin oozes between the substrate 1 and the substrate 1, after the release layer 4 is peeled off, the transparent resin in the oozing portion can be removed by developing the surface opposite to the surface on which the transparent resin layer 3 is formed. An optical waveguide composed of a clad layer and a core layer is formed on the substrate 1 thus obtained, and a mirror portion 9 aligned with the opening 2 is formed in the core layer of the optical waveguide. Thus, an optical waveguide with a mirror can be obtained.

Process (B)
The step (B) of the present invention is a step of removing the release layer 4 after filling the opening 2 with a transparent resin (see FIG. 1B).
A method for removing the release layer 4 is not particularly limited, and may be physically peeled off. If the release layer 4 is an etchable material such as a metal, it may be removed with an etchable liquid. The timing of removal may be after the opening 2 is filled with the transparent resin (after the transparent resin layer 3 is formed), and the photocuring is performed even before the transparent resin filled in the opening 2 is photocured. Later. In addition, when the transparent resin with which the opening part 2 was filled is photocured, normally the transparent resin layer 3 comprised by transparent resin is also photocured simultaneously.

(Process E)
In the present invention, a step of photocuring the transparent resin, that is, a step of photocuring a transparent resin filling at least the opening 2 from the transparent resin layer 3 side after the step A may be performed. Called E.
The method for photocuring the transparent resin is not particularly limited, and an actinic ray for photocuring the transparent resin may be irradiated from the transparent resin layer 3 forming surface side. If the board | substrate 1 becomes a light-shielding part, the inside of the opening part 2 can be photocured efficiently.

(Process F)
Step F is an optional step, and is a step of developing a surface opposite to the transparent resin layer forming surface after Step B. In step A, when the adhesive property between the release layer 4 and the substrate 1 is not good or weak, the transparent resin filled in the opening 2 may wrap around between the release layer 4 and the substrate 1. Step F is a step of removing the wraparound component, and it is preferable to perform this step because contamination of the substrate surface other than the opening on the surface opposite to the transparent resin layer forming surface can be removed. As a method of removing such a wraparound portion, a method of removing the transparent resin using a developer that can be developed and removed after the release layer removing step, which is Step B, is preferably used.

Process (C)
Step (C) of the present invention is a step of forming an optical waveguide composed of a core layer and a clad layer on the substrate 1.
The method for forming the optical waveguide on the substrate 1 is not particularly limited, and an optical waveguide composed of the lower clad layer 6, the core layer 7 and the upper clad layer 8 is prepared in advance and attached to the substrate 1. Alternatively, the lower clad layer 6, the core layer 7, and the upper clad layer 8 may be sequentially formed on the substrate 1.
Further, the step C may be a step of sequentially forming the lower cladding layer 6, the core layer 7, and the upper cladding layer 8 on the transparent resin layer 3, and the adhesion between the lower cladding layer 6 and the transparent resin layer 3. This is preferable in that it is not necessary to consider the adhesion between the substrate and the lower clad layer 6.
There is no particular limitation on the method of forming each layer when the lower clad layer 6, the core layer 7 and the upper clad layer 8 are sequentially formed. A liquid clad layer forming resin composition or a core layer forming resin composition is spin-coated. The clad layer forming resin composition or the core layer forming resin composition may be laminated by a method such as a roll laminator, a vacuum laminator, a press, or a vacuum press.

In the present invention, the transparent resin layer 3 may be the lower clad layer 6. That is, the transparent resin layer 3 and the lower cladding layer 6 can be used together. In this case, if the core layer 7 and the upper cladding layer 8 are sequentially formed on the transparent resin layer 3 by using the above-described method. Good (see FIG. 2).
In the present invention, the transparent resin layer 3 may be the core layer 7. That is, the transparent resin layer 3 and the core layer 7 can be used together (see FIG. 3). In this case, the upper cladding layer 8 may be formed on the transparent resin layer 3.

Process (D)
Step (D) of the present invention is a step of forming the mirror portion 9 in the core layer 7 immediately above the opening 2.
A known method can be applied as a method of forming the mirror portion 9. For example, the core layer 7 can be formed by cutting the core layer 7 using a dicing saw or the like from the surface on which the core layer 7 is formed. The mirror part 9 to be formed is preferably 45 °.
Moreover, it is good also as a mirror part provided with a reflective metal layer by vapor-depositing metals, such as gold | metal | money, using a vapor deposition apparatus for a mirror part. This step (D) may be performed in the step (C) described above after the core layer is stacked, that is, between the step of forming the core layer and the step of forming the upper cladding layer.
The mirror unit 9 is not particularly limited as long as it has a structure that optically converts an optical signal propagated through a core layer installed in a direction parallel to the substrate plane in the direction perpendicular to the substrate, and is an air reflecting mirror having a notch formed at 45 °. It may be a metal reflection mirror in which a reflective metal layer is formed in the notch.
Here, the portion directly above the opening 2 is an optical signal in an optical signal whose optical path is changed from the core pattern to the substrate vertical direction by the mirror, or an optical signal whose optical path is changed from the vertical direction in the substrate to the core pattern by the mirror. Means that the size and positional relationship between the mirror and the opening are such that the substrate around the opening does not interfere with the optical signal and adversely affect optical loss when passing through the opening.

Next, members, materials, etc. used in the production method of the present invention will be described.
(substrate)
There is no restriction | limiting in particular as a material of the board | substrate 1, For example, a glass epoxy resin substrate, a ceramic substrate, a glass substrate, a silicon substrate, a plastic substrate, a metal substrate, a substrate with a resin layer, a substrate with a metal layer, a plastic film, with a resin layer Examples thereof include a plastic film, a plastic film with a metal layer, and an electric wiring board.
In order to expose and cure the transparent resin layers A and B, which will be described in detail later, with different patterns, it is essential that the transparent resin layer A and the transparent resin layer B have a light-shielding effect for the actinic rays for photocuring. . For example, if the actinic ray for photocuring the transparent resin is ultraviolet light, a metal substrate, a plastic substrate that does not transmit ultraviolet light, a glass epoxy resin substrate, and the like are preferably used.
In addition, when a substrate having a low adhesive strength with a transparent resin is used, a substrate with an adhesive layer may be used. The adhesive layer at this time may be provided on the substrate so as not to cover the opening 2. When the transparent resin layer A and the transparent resin layer B are cured with actinic rays having different wavelengths, a transparent substrate may be used.
The thickness of the substrate 1 is not particularly limited as long as the opening 2 can be filled with a transparent resin. The thinner the thickness, the light receiving element, the optical fiber, and the like before the optical signal reflected by the mirror portion 9 spreads. It is preferable because it can receive light. From the above viewpoint, the thickness of the substrate is preferably 5 μm to 1 mm, and more preferably 10 μm to 100 μm from the viewpoint of workability.
The substrate 1 in the present invention has one or more openings 2, but it is preferable to have two or more openings in consideration of bonding with other devices.

(Aperture)
The opening 2 only needs to be perforated in the substrate 1 and can be suitably formed by, for example, drilling or laser processing. Moreover, the through-hole with a metal layer formed by vapor-depositing, sputter | spatter, plating, etc. on the side surface of an opening part may be sufficient.
There is no limitation in particular as an opening shape of the opening part 2, What is necessary is just opening parts, such as circular shape, ellipse shape, and polygonal shape. Further, the side wall may be a vertically formed columnar shape or a tapered frustum shape.
The size of the opening may be in a range that does not affect the light propagation loss, and is preferably a size that allows the mirror to be positioned in the opening when the mirror is viewed from the substrate surface side. . Specifically, when the size of the mirror portion is 50 μm × 50 μm and the opening is circular, the diameter is 50√2 μm or more, which is a circle whose size is inscribed in the opening. Is preferred.

(Transparent resin)
The transparent resin used in the present invention is not particularly limited as long as it is transparent to the optical signal used, and a clad layer forming resin and a core layer forming resin described later can be used. The shape may be liquid or film, but is preferably film when the film thickness is desired to be controlled.
Further, the transparent resin layer 3 formed of the transparent resin may also be used as the lower cladding layer 6 and the core layer 7. When the lower clad layer 6 is also used as a transparent resin, the lower clad layer 6 having an adhesive force with the substrate 1 may be used. When the core layer 7 is also used as a transparent resin, the lower clad layer 6 is patterned. It can be obtained by maintaining the state in which the opening is provided in at least a part of the opening 2 and then forming the core layer 7.

(Release layer)
The release layer 4 may be any material that has releasability with respect to the transparent resin and has flatness on the opening 2, and the materials listed as materials that can be used in the substrate and various resin film materials Can be used.
Note that a material that can be removed after the transparent resin layer 3 is formed (for example, a metal layer is etched away) is also broadly peelable.
Further, a film material having flexibility and toughness can be used as the release layer 4. For example, polyesters such as polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polyethylene, polypropylene, polyamide, polycarbonate, polyphenylene ether, polyether sulfide, polyarylate, liquid crystal polymer, polysulfone, polyethersulfone, polyetheretherketone, polyether Preferred examples include imide, polyamideimide, and polyimide.
The thickness of the release layer 4 is preferably 5 to 10,000 μm. When it is 5 μm or more, there is an advantage that the strength as the release layer 4 is easily obtained, and when it is 10000 μm or less, the transparent resin layer 3 is easily handled when laminated. From the above viewpoint, the thickness of the release layer 4 is more preferably in the range of 10 to 100 μm.

(Lower cladding layer and upper cladding layer)
As the lower clad layer 6 and the upper clad layer 8, a clad layer forming resin composition or a clad layer forming resin film can be used.
The resin composition for forming a clad layer used in the present invention is not particularly limited as long as it is a resin composition that has a lower refractive index than the core layer 7 and is cured by light or heat, and the thermosetting resin composition or the photosensitive resin. A composition can be used conveniently. In the lower clad layer 6 and the upper clad layer 8, the resin composition used for the resin for forming the clad layer may have the same or different components contained in the resin composition, and the refractive index of the resin composition May be the same or different. Further, when the resin composition for forming a cladding layer is used as a transparent resin and patterned by exposure, it is important to use a photosensitive resin composition that can form a pattern with actinic rays.

In the present invention, the method for forming the clad layer is not particularly limited, and may be formed by applying the clad layer forming resin composition or laminating the clad layer forming resin film as described above.
Here, the resin film for forming a clad layer used for laminating can be easily produced by, for example, dissolving the resin composition for forming a clad layer in a solvent, applying it to a carrier film, and removing the solvent.

  The thickness of the lower cladding layer 6 and the upper cladding layer 8 is not particularly limited, but 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 lower cladding layer 6 and the upper cladding layer 8 is more preferably in the range of 10 to 100 μm.

(Core layer)
Hereinafter, the core layer 7 in the manufacturing method of the present invention will be described. As the core layer 7, a core layer forming resin or a core layer forming resin film can be used.
The core layer forming resin is preferably designed to have a refractive index higher than that of the cladding layers 6 and 8 and capable of forming a core pattern with actinic rays. The method of forming the core layer before patterning is not limited, and examples thereof include a method of applying the core layer forming resin composition by a conventional method.

  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. When the thickness of the core layer 7 after finishing 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 forming the optical waveguide, and when the thickness is 100 μm or less. In the coupling with the light emitting / receiving element or the optical fiber after the optical waveguide is formed, there is an advantage that the coupling efficiency is improved. From the above viewpoint, the thickness of the film is preferably in the range of 30 to 90 μm, and the film thickness may be appropriately adjusted in order to obtain the thickness.

(Reinforcement plate)
The optical waveguide of the present invention may have a reinforcing plate 10 in the vicinity of the opening 2 on the surface opposite to the surface on which the transparent resin layer 3 is formed on the substrate 1 (see FIG. 4).
The reinforcing plate 10 may be formed in the vicinity of the opening 2 on the surface opposite to the surface on which the transparent resin layer 3 is formed before the transparent resin layer 3 is formed. From this point of view, the elastic modulus is preferably higher than that of the transparent resin, and more preferably a metal layer.
Although there is no limitation in particular as a kind of metal, various metals, such as Au, Ag, Cu, Cr, Al, Ni, Pd, are used. An optical signal whose optical path has been changed from the mirror portion in the substrate plane direction is reflected on the side wall portion of the reinforcing plate 10 and is also guided to the light receiving element, so that it is a metal with high reflectivity from the viewpoint of reducing loss. Au, Ag, Cu and the like are preferable.

Although it does not specifically limit as a shape of a reinforcement board, It is preferable to install so that the opening part 2 may be bordered. Further, the metal layer may be provided on the inner wall of the opening 2, whereby the reinforcing plate 10 can be more firmly bonded to the substrate 1. Specifically, after providing metal foil on both surfaces of the substrate 1 and forming the opening 2, the inner wall of the opening 2 can be made a metal layer by using Cu plating, Au plating, or the like.
Further, the thickness of the reinforcing plate is not particularly limited, but may be a thickness that can be embedded with a transparent resin. From this viewpoint, the thickness is preferably 3 to 50 μm, more preferably 5 to 38 μm.

The method of forming the reinforcing plate 10 on the substrate 1 is not particularly limited. However, when a metal is used for the reinforcing plate, the method of patterning the reinforcing plate is a metal layer on the surface of the substrate 1 (at least one surface). After forming the pattern resist on the metal layer using the substrate 1 having the following, the metal layer is patterned by etching or the like, and the pattern resist is peeled off.
The opening 2 can be formed by patterning the metal layer by the above method after drilling the metal layer (reinforcing plate) even if the opening is formed by drilling after the metal layer is patterned. May be used.

(Optical waveguide obtained by the production method of the present invention)
In the optical waveguide obtained by the manufacturing method of the present invention, the substrate 1 has at least one opening 2 as shown in FIG. 1 (d), and the transparent resin layer 3 is formed on one surface of the substrate 1. In addition, the inside of the opening 2 is filled with a transparent resin, and a lower clad layer 6, a core layer 7 and an upper clad layer 8 are sequentially formed on the transparent resin layer 3, and a mirror part 9 is formed immediately above the opening 2. The optical waveguide with a mirror which has is mentioned. Further, as shown in FIG. 2, in FIG. 1 (d), an optical waveguide with a mirror in which the transparent resin layer 3 and the lower cladding layer 6 are used together, or a part of the transparent resin layer 3 (see FIG. An optical waveguide with a mirror using the lower cladding layer 6 as the periphery of the opening 2 and the core layer 7 as a part of the transparent resin layer 3 (center of the opening 2) is also an optical waveguide of the present invention. Further, as shown in FIG. 4, a reinforcing plate 10 may be provided around the opening 2 on the surface opposite to the surface on which the transparent resin 3 is formed. At this time, the reinforcing plate 10 is also regarded as a part of the substrate 1.

The optical waveguide obtained by the manufacturing method of the present invention has an advantage that good optical communication can be performed regardless of the type of substrate 1 (transmittance of the optical signal) because the optical signal is transmitted through the opening 2.
Even if the transparency of the substrate 1 is high, the substrate usually has a higher refractive index than the transparent resin, the lower cladding layer, and the core layer. Fresnel loss occurs due to the difference in refractive index between the substrate and the substrate. On the other hand, in the optical waveguide obtained by the manufacturing method of the present invention, the transparent resin having a refractive index lower than that of the substrate 1 is filled in the opening 2, and light propagates in the transparent resin. The Fresnel loss can be reduced.

  Moreover, since the opening 2 is filled with the transparent resin after the release layer 4 is provided, the transparent resin can be filled up to the height of the surface of the substrate 1 opposite to the surface on which the transparent resin layer 3 is formed. Therefore, since the transparent resin 3 can be filled to almost the same height as the surface of the substrate 1, it is easy to ensure the flatness of the substrate. Accordingly, when the optical waveguide with a mirror is inserted into a connector with an optical element built-in, mounted with a housing with an optical element built-in, or when wiring formation or processing is performed on the surface of the substrate 1, the handling is possible. It becomes easy.

EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to a following example, unless the summary is exceeded.
Example 1
[Preparation of resin film for forming clad layer]
[(A) Base polymer; production of (meth) acrylic polymer (A-1)]
46 parts by mass of propylene glycol monomethyl ether acetate and 23 parts by mass of methyl lactate were weighed in a flask equipped with a stirrer, a cooling pipe, a gas introduction pipe, a dropping funnel, and a thermometer, and stirred while introducing nitrogen gas. . The liquid temperature was raised to 65 ° C., 47 parts by weight of methyl methacrylate, 33 parts by weight of butyl acrylate, 16 parts by weight of 2-hydroxyethyl methacrylate, 14 parts by weight of methacrylic acid, 2,2′-azobis (2,4-dimethylvaleronitrile ) A mixture of 3 parts by mass, 46 parts by mass of propylene glycol monomethyl ether acetate and 23 parts by mass of methyl lactate was added dropwise over 3 hours, followed by stirring at 65 ° C. for 3 hours, and further stirring at 95 ° C. for 1 hour. A (meth) acrylic polymer (A-1) solution (solid content: 45% by mass) was obtained.

[Measurement of weight average molecular weight]
As a result of measuring the weight average molecular weight (in terms of standard polystyrene) of (A-1) using GPC (“SD-8022”, “DP-8020”, and “RI-8020” manufactured by Tosoh Corporation), 3. It was 9 × 10 ⁴ . The column used was “Gelpack GL-A150-S” and “Gelpack GL-A160-S” manufactured by Hitachi Chemical Co., Ltd.
[Measurement of acid value]
As a result of measuring the acid value of A-1, it was 79 mgKOH / g. In addition, the acid value was computed from the amount of 0.1 mol / L potassium hydroxide aqueous solution required for neutralizing A-1 solution. At this time, the point at which the phenolphthalein added as an indicator changed color from colorless to pink was defined as the neutralization point.

[Preparation of resin varnish for forming clad layer]
(A) As the base polymer, 84 parts by mass (solid content: 45% by mass) of the A-1 solution (solid content: 45% by mass), (B) Urethane (meth) acrylate having a polyester skeleton as the photocuring component (Shin Nakamura) 33 parts by mass of “U-200AX” manufactured by Chemical Industry Co., Ltd., and 15 parts by mass of urethane (meth) acrylate having a polypropylene glycol skeleton (“UA-4200” manufactured by Shin-Nakamura Chemical Co., Ltd.), (C) heat As a curing component, 20 parts by mass of a polyfunctional block isocyanate solution (solid content: 75% by mass) obtained by protecting an isocyanurate type trimer of hexamethylene diisocyanate with methyl ethyl ketone oxime (“Sumijour BL3175” manufactured by Sumika Bayer Urethane Co., Ltd.) (Solid content 15 parts by mass), (D) As a photopolymerization initiator, 1- [4- (2-hydroxy ester) Xyl) phenyl] -2-hydroxy-2-methyl-1-propan-1-one (“Irgacure 2959” manufactured by Ciba Japan Co., Ltd.), 1 part by mass, bis (2,4,6-trimethylbenzoyl) phenylphosphine 1 part by mass of oxide (“Irgacure 819” manufactured by Ciba Japan Co., Ltd.) and 23 parts by mass of propylene glycol monomethyl ether acetate as an organic solvent for dilution were mixed with stirring. After pressure filtration using a polyflon filter having a pore size of 2 μm (“PF020” manufactured by Advantech Toyo Co., Ltd.), degassing was performed under reduced pressure to obtain a resin varnish for forming a cladding layer.
The resin composition for forming a clad layer obtained above is coated on a non-treated surface of a PET film (“Cosmo Shine A4100” manufactured by Toyobo Co., Ltd., thickness 50 μm) as a support film. -MC, manufactured by Hirano Tech Seed Co., Ltd.) After drying at 100 ° C. for 20 minutes, a surface release treatment PET film (“Purex A31” manufactured by Teijin DuPont Films Co., Ltd., thickness 25 μm) is applied as a protective film to form a cladding layer A resin film was obtained. At this time, the thickness of the resin layer can be arbitrarily adjusted by adjusting the gap of the coating machine. In the present embodiment, the thickness of the lower clad layer 6 and the transparent resin layer 3 used in the examples is as follows. It describes. Moreover, the film thickness after hardening of the lower clad layer 6 and the transparent resin layer 3 and the film thickness after coating were the same. The film thickness of the upper clad layer forming resin film used in this example is also described in the examples. The film thickness of the upper clad layer forming resin film described in the examples is the film thickness after coating.

[Preparation of resin film for core layer formation]
(A) As a base polymer, 26 parts by mass of a phenoxy resin (trade name: Phenotote YP-70, manufactured by Toto Kasei Co., Ltd.), and (B) 9,9-bis [4- (2- Acrylyloxyethoxy) phenyl] fluorene (trade name: A-BPEF, 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) 1 part by mass of bis (2,4,6-trimethylbenzoyl) phenylphosphine oxide (trade name: Irgacure 819, manufactured by Ciba Specialty Chemicals) -[4- (2-hydroxyethoxy) phenyl] -2-hydroxy-2-methyl-1-propan-1-one (trade name: Irgacu 2959, manufactured by Ciba Specialty Chemicals Co., Ltd.) A resin varnish B for forming a core layer was prepared by the same method and conditions as in the above production example except that 1 part by mass and 40 parts by mass of propylene glycol monomethyl ether acetate were used as the organic solvent. did. Thereafter, pressure filtration and degassing under reduced pressure were performed under the same method and conditions as in the above production example.
On the non-treated surface of the PET film (trade name: Cosmo Shine A1517, manufactured by Toyobo Co., Ltd., thickness: 16 μm), which is a support film, the core layer-forming resin varnish B obtained above is used. Apply and dry in the same manner as above, and then attach a release PET film (trade name: PUREX A31, Teijin DuPont Films, Inc., thickness: 25 μm) as a protective film so that the release surface is on the resin side A resin film for forming a core 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 of the resin film for forming the core layer used is described in the examples. The film thickness of the core layer forming resin film described in the examples is the film thickness after coating.

[Production of substrate with opening]
150 mm × 150 mm polyimide film ((polyimide; Upilex RN (manufactured by Ube Nitto Kasei), thickness: 25 μm), drilled to form two openings with a diameter of 150 μm (distance between center of opening: 100 mm) as substrate 1 A substrate 1 with an opening 2 was obtained.

[Filling the opening]
A 150 mm × 150 mm release PET film (trade name: Purex A31, Teijin DuPont Films Co., Ltd., thickness: 25 μm) is released as the release layer 4 on the surface opposite to the surface on which the transparent resin layer 3 is formed on the substrate 1. The mold surface is placed on the substrate 1 side, the 25 μm-thick clad layer forming resin film obtained above is used as the transparent resin layer 3, the protective film is peeled off, and the substrate with the opening 2 obtained above. 1. Vacuum-pressurized laminator (MVLP-500, manufactured by Meiki Seisakusho Co., Ltd.), vacuumed to 500 Pa or less, then heated under conditions of pressure 0.4 MPa, temperature 110 ° C., pressurization time 30 seconds Crimped and laminated (see FIG. 1A).

Subsequently, 300 mJ / cm ^{2 of} ultraviolet rays (wavelength 365 nm) was irradiated from the transparent resin layer 3 side through a support film with an ultraviolet exposure machine (EXM-1172, manufactured by Oak Manufacturing Co., Ltd.). Thereafter, the support film of the transparent resin layer 3 and the release layer 4 are peeled off, and the release layer 4 and the substrate 1 opposite to the surface on which the transparent resin layer 3 is formed using a developer (1% potassium carbonate aqueous solution). The resin sneaking in between was developed and removed. Subsequently, the substrate was washed with water, dried and cured by heating at 170 ° C. for 1 hour, and a substrate 1 in which the opening 2 was filled with the transparent resin 3 was obtained (see FIG. 1B).

On the transparent resin layer 3 of the substrate obtained above, the protective film is peeled off using the 10 μm-thick resin film for forming a clad layer obtained above as a lower clad layer 6, and then with the opening 2 obtained above. A vacuum pressurization laminator (MVLP-500, manufactured by Meiki Seisakusho Co., Ltd.) was used on both surfaces of the substrate 1 and evacuated to 500 Pa or less. Was laminated by thermocompression bonding. Subsequently, ultraviolet rays (wavelength 365 nm) were irradiated from the support film side of the lower clad layer 6 with 3.0 J / cm ² using the above-described UV exposure machine, the support film was peeled off, and then dried and cured at 170 ° C. for 1 hour. Then, the lower clad layer 6 was formed.

  Next, on the lower clad layer 6 formed above, the protective film was peeled off using the 50 μm-thick core layer-forming resin film obtained above as a core layer 7, and then a roll laminator (Hitachi Chemical Technoplant Co., Ltd.). Manufactured by HLM-1500) under the conditions of a pressure of 0.4 MPa, a temperature of 50 ° C., and a laminating speed of 0.2 m / min, and then the above-described vacuum pressure laminator (manufactured by Meiki Seisakusho, MVLP-500) After vacuuming to 500 Pa or less, thermocompression bonding was performed under the conditions of a pressure of 0.4 MPa, a temperature of 70 ° C., and a pressurization time of 30 seconds.

Subsequently, a negative photomask having an opening with a core pattern width of 50 μm is aligned so that the core pattern is formed on the opening, and from the support film side using the ultraviolet exposure machine. Ultraviolet rays (wavelength 365 nm) were irradiated at 0.8 J / cm ² , and then after exposure for 5 minutes at 80 ° C., heating was performed. Thereafter, the PET film as the support film was peeled off, and the core pattern was etched using a developer (propylene glycol monomethyl ether acetate / N, N-dimethylacetamide = 8/2, mass ratio). Then, it wash | cleaned using the washing | cleaning liquid (isopropanol), and heat-dried at 100 degreeC for 10 minute (s), and formed the core pattern.

From the obtained core pattern, the 55 μm-thick clad layer-forming resin film obtained above was used as the lower clad layer 6, and the protective film was peeled off, followed by vacuum pressurization laminator (manufactured by Meiki Seisakusho, MVLP- 500) and evacuated to 500 Pa or less, and then laminated by thermocompression bonding under conditions of a pressure of 0.4 MPa, a temperature of 110 ° C., and a pressurization time of 30 seconds. Subsequently, ultraviolet rays (wavelength 365 nm) were irradiated from the support film side of the lower clad layer 6 with 3.0 J / cm ² using the above-described UV exposure machine, the support film was peeled off, and then dried and cured at 170 ° C. for 1 hour. Then, an optical waveguide was formed (see FIG. 1C).

(Formation of mirror part)
A 45 ° mirror portion 9 was formed on the opening 2 using a dicing saw (DAC552, manufactured by Disco Corporation) from the upper clad layer 8 side of the obtained optical waveguide (see FIG. 1D).

(Measurement of optical loss of mirror part)
An optical signal of 850 nm is incident from the mirror part of the obtained optical waveguide with a mirror using the optical fiber A (GI50, NA = 0.2), is transmitted through the core pattern, and is output from another mirror part. Was measured using the optical fiber B (GI50, NA = 0.2), and the optical loss (A) was measured. At this time, the distance between the surface of the substrate 1 and the optical fibers A and B was 30 μm (the distance between the columnar transparent member 5 and the optical fibers A and B; 5 μm). Next, the two mirror portions were cut using the above dicing saw to obtain an optical waveguide without a mirror. Next, using the optical fiber A and the optical fiber B, the optical fiber A was aligned on the incident part side and the optical fiber B was aligned on the output part side in the direction coaxial with the core pattern, and the optical loss (B) was measured.
The total light loss (C) of the two mirror parts was calculated according to the following formula.
(Formula) (C) = (A)-(B)
The total optical loss of the two mirror portions of the obtained optical waveguide with a mirror was 1.98 dB.

Example 2
An optical waveguide with a mirror was produced in the same manner as in Example 1 except that the transparent resin layer 3 had a thickness of 25 μm and was used as the lower cladding layer 6 (see FIG. 2).
The total optical loss of the two mirror portions of the obtained optical waveguide with a mirror was 1.92 dB.

Example 3
In Example 2, when the transparent resin layer 3 was exposed, ultraviolet light (wavelength 365 nm) was irradiated at 0.3 J / cm ² through a negative photomask having the center of the opening (80 μm) as a light-shielding portion to be transparent. After the support film of the resin layer 3 and the release layer 4 are peeled off, the center of the opening is developed and removed, then washed with water, and further, 3.0 J / cm from the lower clad layer 6 side using the above exposure machine. ² irradiation, heat drying and curing at 170 ° C. for 1 hour. Next, a 150 mm × 150 mm release PET film (trade name: PUREX A31, Teijin DuPont Films, Inc., thickness: 25 μm) is used as the release layer 4, and the release surface is the substrate 1 side (the lower clad layer 6 formation surface and 2) and laminated on the substrate 1 from the transparent resin layer 3 side as a core layer 7 with a resin film for core layer formation having a thickness of 50 μm obtained by peeling off the protective film on the lower clad layer. After aligning the opening of 200 μm diameter and the opening 2 of the substrate 1 through a negative photomask having an opening of 200 μm in diameter and a 50 μm opening connecting the openings, the ultraviolet light Using an exposure machine, ultraviolet rays (wavelength 365 nm) were irradiated from the support film side at 0.8 J / cm ² , and then after exposure at 80 ° C. for 5 minutes, heating was performed. Thereafter, the PET film as the support film was peeled off, and the core pattern was etched using a developer (propylene glycol monomethyl ether acetate / N, N-dimethylacetamide = 8/2, mass ratio). Then, it wash | cleaned using the washing | cleaning liquid (isopropanol), and heat-dried at 100 degreeC for 10 minute (s), and formed the core pattern.
Subsequent steps were performed in the same manner as in Example 2 to obtain an optical waveguide with a mirror (see FIG. 3).
The total light loss of the two mirror portions of the obtained optical waveguide with a mirror was 1.90 dB.

Example 4
A 150 mm × 150 mm single-sided copper foil-coated polyimide film (polyimide; Upilex VT (manufactured by Ube Nitto Kasei), thickness: 25 μm, copper foil: 12.5 μm) as the substrate 1 is drilled to provide two openings with a diameter of 150 μm (Distance between centers of openings: 100 mm) to form a substrate 1 with openings 2.
Thereafter, a photosensitive dry film resist (trade name: Photec, manufactured by Hitachi Chemical Co., Ltd., thickness: 25 μm) is applied to the copper foil surface using a roll laminator (HLM-1500, manufactured by Hitachi Chemical Technoplant Co., Ltd.), and the pressure is 0. .4 MPa, temperature 110 ° C., lamination speed 0.4 m / min, and then the same center as the opening center from the photosensitive dry film resist side with an ultraviolet exposure machine (EXM-1172, manufactured by Oak Manufacturing Co., Ltd.) UV light (wavelength 365 nm) is irradiated through a negative photomask having an opening with a diameter of 200 μm at 120 mJ / cm ² , and an unexposed portion of the photosensitive dry film resist is diluted with a dilute solution of 5 mass% sodium carbonate at 35 ° C. Removed. Thereafter, the photosensitive dry film resist was removed using a ferric chloride solution, and the exposed copper foil was removed by etching, and an exposed portion was removed using a 10 mass% sodium hydroxide aqueous solution at 35 ° C. The photosensitive dry film resist was removed to form a reinforcing plate 10. In the subsequent steps, an optical waveguide with a mirror was formed as in Example 2 (see FIG. 4).
The total optical loss of the two mirror portions of the obtained optical waveguide with a mirror was 2.00 dB.

Comparative Example 1
An optical waveguide with a mirror was produced in the same manner as in Example 1 except that the opening 2 of the substrate 1 was not formed.
The total light loss of the two mirror portions of the obtained optical waveguide with a mirror was 2.55 dB.

Comparative Example 2
An optical waveguide with a mirror was produced in the same manner as in Example 2 except that the opening 2 of the substrate 1 was not formed.
The total optical loss of the two mirror portions of the obtained optical waveguide with a mirror was 2.45 dB.

  The optical waveguide obtained by the manufacturing method of the present invention can be applied to various fields such as various optical devices and optical interconnections.

1. Substrate 2. Opening 3. 3. Transparent resin layer Release layer 6. 6. Lower clad layer Core layer 8. 8. Upper clad layer Mirror part 10. Reinforcing plate (part of substrate)

Claims (7)

  (A) a step of providing a release layer on one surface on a substrate having at least one opening, forming a transparent resin layer made of a transparent resin on the other surface, and filling the opening with a transparent resin; (B) removing the release layer after filling the opening with a transparent resin, (C) forming an optical waveguide composed of a core layer and a clad layer on the substrate, and (D) the opening. And a step of forming a mirror portion in the core layer directly above.   The method for manufacturing an optical waveguide according to claim 1, wherein the step (C) is a step of sequentially forming a lower clad layer, a core layer, and an upper clad layer on the substrate.   The method for manufacturing an optical waveguide according to claim 1, wherein the step (C) is a step of sequentially forming a lower clad layer, a core layer, and an upper clad layer on the transparent resin layer.   The method for manufacturing an optical waveguide according to claim 1, wherein the transparent resin layer is a lower clad layer or a core layer.   The transparent resin is a photosensitive transparent resin, and further includes a step (E) of photocuring a transparent resin filling at least the opening from the transparent resin layer side after the step (A). The manufacturing method of the optical waveguide in any one of 1-4.   The method for manufacturing an optical waveguide according to claim 5, further comprising a step (F) of developing a surface opposite to the transparent resin layer forming surface after the step (B).   An optical waveguide manufactured by the method according to claim 1.