JP2005164650A - Manufacturing method of optical waveguide and optical waveguide - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide manufacturing methods of an optical waveguide in which the number of processes of the waveguide manufacturing is made small, productivity is superior and heat resistance of the optical waveguide is made superior. <P>SOLUTION: The manufacturing method of an optical waveguide includes a process in which a resin film made of resin composition that includes norbornene resin is irradiated with light beams to form the waveguide. The other manufacturing method of an optical waveguide includes a process in which a resin film made of resin composition that includes norbornene resin is irradiated with light beams in a prescribed pattern to change the resin structure in the resin film and the optical waveguide is formed by providing differences in the refractive indexes of irradiated sections and not yet irradiated sections. The norbornene resin has a norbornadiene structure whose structure is changed by irradiation of light beams. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an optical waveguide manufacturing method and an optical waveguide.

In optical communication, which is rapidly gaining interest in recent years, optical branching couplers (optical couplers), optical multiplexers / demultiplexers, and the like are listed as important optical components, and optical waveguide devices used for these are promising.
Conventional optical waveguide type devices use silica-based optical waveguides, but silica-based optical waveguides are made of quartz glass and are therefore brittle and require high-temperature processes and vacuum processes such as reactive ion etching. Therefore, there is a drawback that the manufacturing cost is increased.

On the other hand, many polymer-based optical waveguides have been made as alternatives to quartz-based waveguides.
In the conventional polymer-based optical waveguide, as a method for producing a relief structure of a waveguide pattern, for example, a pattern is formed with a photosensitive resin on a polyimide resin layer, and etching is performed by a reactive ion etching (RIE) method or the like. And the method of peeling off the excess photosensitive resin is mentioned (for example, refer patent document 1). However, since these methods use complicated methods, the number of steps for the waveguide fabrication process is increased, which has an influence on the manufacturing cost and the yield. In addition, the polymer-based optical waveguide has a problem that the optical loss is large depending on the wavelength range of light used depending on the type of polymer.

  As a technique not using the RIE method, a plastic optical waveguide composed of polymethyl methacrylate containing a norbornadiene structure that is isomerized by light has been proposed (for example, Patent Document 2). Conventionally, it is known that norbornadiene and its derivative compounds are converted to quadricyclane and its derivative compounds by light irradiation, and the absorbed light energy is accumulated as strain energy. Furthermore, this quadricyclane and its derivative compound are easily reconverted to the original norbornadiene and its derivative by heating above the glass transition temperature or contact with the catalyst, and heat energy is released during this reconversion. For these reasons, norbornadiene compounds are attracting attention as having functions of storing and exchanging light and thermal energy, and at the same time, utilizing the change in electron density distribution accompanying this photoisomerization reaction, optical waveguide materials Application as is proposed. However, the material formed of a polymer compound having a norbornadiene structure in the side chain that has been used so far has a heat resistance of around 100 ° C., so the usage environment is limited and the mounting circuit In order to incorporate them, it is necessary to pass through a soldering process of several hundred degrees, resulting in a problem that the fusion with the electric circuit board is deteriorated. In addition, it was formed from high-molecular compounds having a low glass transition temperature, which have been used so far, in order to easily reconvert from quadricyclane and its derivatives to the original norbornadiene and its derivatives by heating above the glass transition temperature. The material has a problem in the pattern stability of the optical waveguide.

JP 05-164929 A Japanese Patent Laid-Open No. 10-148727

  An object of the present invention is to provide an optical waveguide manufacturing method that can provide a heat-resistant optical waveguide with less man-hours for the waveguide fabrication process, excellent productivity, and small optical loss.

（式（１）中、Ｒ₁は、ノルボルナジエン誘導体と反応可能な１価の官能基を示す。）
（５） 前記式（１）で表されるモノマーは、式（１）におけるＲ₁として、エポキシ基またはヒドロキシル基で構成される１価の基を有するものであるモノマーの少なくとも１種である請求項４に記載の光導波路の製造方法。
（６） 前記重合体は、ノルボルナジエン誘導体と反応可能な官能基を有する上記式（１）で表されるモノマーと下記式（２）で表されるモノマーとを重合して得られたものである第（４）項または第（５）項に記載の光導波路の製造方法。

（式（２）中、Ｒ₂は、ノルボルナジエン誘導体と反応しない１価の官能基を示す。）
（７） 前記ノルボルネン系樹脂のガラス転移温度は、１８０℃以上である第（１）項ないし第（６）項のいずれかに記載の光導波路の製造方法。
（８） 前記ノルボルネン系樹脂の含有量は、前記樹脂組成物全体の５０〜９９．５重量％である第（１）項ないし第（７）項のいずれかに記載の光導波路の製造方法。
（９） 前記樹脂膜のガラス転移温度は、１８０℃以上である第（１）項ないし第（８）項のいずれかに記載の光導波路の製造方法。
（１０） 前記樹脂膜の厚さは、５〜１００μｍである第（１）項ないし第（９）項のいずれかに記載の光導波路の製造方法。
（１１） 第（１）項ないし第（１０）項のいずれかに記載の光導波路の製造方法によって得られることを特徴とする光導波路。 Such an object is achieved by the present invention described in the following (1) to (11).
(1) A method for producing an optical waveguide, comprising a step of irradiating a resin film comprising a resin composition containing a norbornene-based resin with light to form an optical waveguide,
The norbornene-based resin has a norbornadiene structure whose structure is changed by light irradiation.
(2) A resin film composed of a resin composition containing a norbornene resin is irradiated with light in a predetermined pattern to change the resin structure in the resin film, and the refractive index of the irradiated portion and the unirradiated portion is changed. A method of manufacturing an optical waveguide having a step of forming an optical waveguide by providing a difference,
The norbornene-based resin has a norbornadiene structure whose structure is changed by light irradiation.
(3) The optical waveguide manufacturing method according to (1) or (2), wherein the norbornene-based resin skeleton is a polymer in which a norbornane structure is substantially continuously polymerized.
(4) The norbornene-based resin is obtained by reacting a norbornadiene derivative with a side chain of a polymer containing a monomer represented by the following formula (1) having a functional group capable of reacting with a norbornadiene derivative. The method for manufacturing an optical waveguide according to any one of (1) to (3).

(In formula (1), R ₁ represents a monovalent functional group capable of reacting with a norbornadiene derivative.)
(5) The monomer represented by the formula (1) is at least one monomer having a monovalent group composed of an epoxy group or a hydroxyl group as R ₁ in the formula (1). Item 5. A method for manufacturing an optical waveguide according to Item 4.
(6) The polymer is obtained by polymerizing a monomer represented by the above formula (1) having a functional group capable of reacting with a norbornadiene derivative and a monomer represented by the following formula (2). The method for producing an optical waveguide according to item (4) or (5).

(In formula (2), R ₂ represents a monovalent functional group that does not react with the norbornadiene derivative.)
(7) The method for manufacturing an optical waveguide according to any one of (1) to (6), wherein the norbornene-based resin has a glass transition temperature of 180 ° C. or higher.
(8) The method for producing an optical waveguide according to any one of (1) to (7), wherein the content of the norbornene-based resin is 50 to 99.5% by weight of the entire resin composition.
(9) The method for producing an optical waveguide according to any one of (1) to (8), wherein the glass transition temperature of the resin film is 180 ° C. or higher.
(10) The method for manufacturing an optical waveguide according to any one of (1) to (9), wherein the resin film has a thickness of 5 to 100 μm.
(11) An optical waveguide obtained by the method for manufacturing an optical waveguide according to any one of (1) to (10).

  According to the present invention, since a core layer for forming a waveguide can be formed without using a conventional complicated method, it is possible to manufacture an optical waveguide with less man-hours for the waveguide manufacturing process and excellent productivity. In addition, an optical waveguide having a small heat loss and heat resistance can be provided.

Hereinafter, the manufacturing method of the optical waveguide of this invention is demonstrated.
The method for producing an optical waveguide of the present invention is a method for producing an optical waveguide having a step of forming an optical waveguide by irradiating light onto a resin film composed of a resin composition containing a norbornene-based resin, wherein the norbornene-based method is used. The resin is characterized by having, in the side chain, norbornadiene whose structure changes upon irradiation with light.
Further, the method for manufacturing an optical waveguide of the present invention irradiates a predetermined pattern with light on a resin film composed of a resin composition containing a norbornene resin, changes the resin structure in the resin film, and Is a method of manufacturing an optical waveguide having a step of forming an optical waveguide by providing a difference in refractive index between the non-irradiated portion and the norbornene-based resin, wherein the norbornene-based resin has norbornadiene whose side chain is structurally changed by light irradiation. It is characterized by.

Hereinafter, although the manufacturing method of the optical waveguide of this invention is demonstrated based on suitable embodiment, this invention is not limited to this.
1 and 2 are cross-sectional views schematically showing an example of a method for manufacturing an optical waveguide according to the present invention.
FIG. 1C shows a resin film 2 in which a core portion 21 and a clad portion 22 are formed on the substrate 1, and FIG. 2C shows both surfaces of the resin film 2 having the core portion 21 and the clad portion 22. 2 is a cross-sectional view showing an optical waveguide 10 having a first cladding layer 3 and a second cladding layer 4.

In the method of manufacturing an optical waveguide according to the present invention, the core portion 21 and the cladding portion 22 are formed on the resin film 2 as step A (FIG. 1). Moreover, the optical waveguide 10 is manufactured as step B (FIG. 2).
Hereinafter, each step will be described.

Step A
In Step A, the resin film 2 in which the core portion 21 and the cladding portion 22 are formed is manufactured (see FIG. 1).
First, a resin film 2 made of a resin composition containing a norbornene resin is formed on one surface of the substrate 1 (FIG. 1A). Thereby, an optical waveguide with little optical loss can be obtained.
Examples of the substrate 1 include a resin film made of a resin such as a silicon substrate, a stainless steel substrate, polyester, and polyimide.
Further, the substrate 1 may be a substrate 1 that functions as a clad layer, as will be described later. Examples of such a substrate 1 include a glass substrate, a silicon substrate with an oxide film, and a resin film made of a norbornene resin. When such a substrate 1 is used, one of the clad layers described later need not be provided.

As described later, the norbornene-based resin is characterized in that a norbornadiene structure whose structure changes with light or a group having the same is bonded to a side chain. Thereby, the refractive index of an irradiation part can be changed with light.
Examples of the polymer constituting the main chain of the norbornene-based resin include norbornene addition polymers.

  The weight average molecular weight of the norbornene resin is not particularly limited, but is preferably 10,000 to 5,000,000, and particularly preferably 50,000 to 500,000. When the weight average molecular weight is within the above range, the strength of the resin film 2 is particularly excellent, and the mechanical properties in the case of finally forming an optical waveguide are excellent.

  The content of the norbornene-based resin is not particularly limited, but is preferably 50 to 99.5% by weight, particularly preferably 70 to 95% by weight, based on the entire resin composition. If the content is less than the lower limit, the effect of reducing the optical loss of the optical waveguide may be reduced, and if the content exceeds the upper limit, the long-term reliability may be reduced.

  The resin composition includes additives such as antioxidants, antifoaming agents, leveling agents, adhesion assistants, organic solvents, flame retardants, monophenol-based, bisphenol-based, It can contain radical trapping agents such as phenolic and aromatic amines.

  Although the thickness of the resin film 2 is not specifically limited, 5-100 micrometers is preferable and 20-70 micrometers is especially preferable. If the thickness is less than the lower limit, it may be difficult to form the core portion 21, and if the thickness exceeds the upper limit, light may not reach the lower part of the resin film 2.

  Although the glass transition temperature of the resin film 2 is not specifically limited, 180 degreeC or more is preferable and especially 200-350 degreeC is preferable. If the glass transition temperature is less than the lower limit, the effect of improving the heat resistance may be reduced, and if the glass transition temperature exceeds the upper limit, the flexibility of the resin film 2 may be reduced.

Examples of the method for forming the resin film 2 on the substrate 1 include methods such as spin coating, dipping, table coating, spraying, applicator, curtain coating, and die coating. Among these, the spin coating method, the table coating method, and the die coating method are preferable. Thereby, a resin film can be manufactured with high productivity.
Specifically, the resin composition containing the norbornene-based resin film is dissolved in a solvent such as toluene xylene, mesitylene, cyclohexane, tetrahydrofuran, etc., and impurities and particles that cause light scattering are filtered, and then the resin composition Can be applied to the substrate 1 by the above-described method, and dried by a method such as heating, hot air, air drying, or infrared rays to form the resin film 2.
Alternatively, the resin layer 2 may be formed by bonding an uncured resin film formed of the norbornene-based resin previously formed on the substrate 1 by a method such as lamination.

Next, masking 12 is performed so as to form a predetermined pattern on the resin film 2, and light 11 is irradiated (FIG. 1B). Thereby, the clad part 22 can be formed in the part irradiated with the light 11.
The reason why the clad portion 22 is formed in the resin film 2 by the irradiation of the light 11 is as follows.
As described above, the norbornene-based resin has norbornadiene that changes its structure with light. Therefore, the structure of the norbornene-based resin in the portion irradiated with the light 11 of the resin film 2 changes, resulting in a change in refractive index. Therefore, a difference in refractive index can be provided between the irradiated portion and the unirradiated portion.

Specifically, the reason why the refractive index changes due to the structural change of the norbornene resin is as follows.
By the light irradiation, the norbornadiene structure or a group having the norbornadiene structure bonded to the side chain of the norbornene-based resin in the irradiated portion is converted into a quadricyclane structure or a group having the same. In the norbornene-based resin in which this photoisomerization reaction has occurred, a change in the electron density distribution occurs, the refractive index of the portion irradiated with the light becomes low, and the clad portion 22 of the optical waveguide is formed. The part forms the core part 21.

  As a method for synthesizing a norbornene-based resin having a norbornadiene structure that changes its structure upon irradiation with light, an addition polymer of norbornene having a functional group capable of reacting with a norbornadiene derivative in the side chain is synthesized, and then this functional group is converted into a functional group. A method of binding a norbornadiene derivative by use is preferable. In this case, a norbornene monomer having the functional group in the side chain, for example, two or more kinds of norbornene monomers including the norbornene monomer represented by the above formula (1) are subjected to addition copolymerization, and the copolymerization ratio of the copolymer It is possible to adjust the norbornadiene content in the norbornene-based resin. The monovalent functional group capable of reacting with the norbornadiene derivative includes at least one epoxy group or hydroxyl group, a group having any of these groups, or a part or all of hydrogens of these groups substituted by a substituent. The ones made are preferred. Examples of the substituent substituted with hydrogen include an alkyl group such as a butyl group and a hexyl group, a halogen group such as a fluoro group, an alkyl group containing a halogen group such as a hexafluoro group, an alkoxysilane group, and an ether group. Can be mentioned.

The monomer having a functional group capable of reacting with the norbornadiene derivative in the side chain is composed of an epoxy group or a hydroxyl group as R ₁ in the formula (1) among the norbornene monomers represented by the formula (1). Monomers having a monovalent group are preferred, and monomers represented by the following formulas (3) to (4) are more preferred. These monomers can use 1 type (s) or 2 or more types.

（式（３）中、ｍは０〜１０までの整数を表す。）

(In formula (3), m represents an integer from 0 to 10.)

（式（４）中、Ｒ₃は、２価の有機基を示す。）

(In the formula (4), R ₃ represents a divalent organic group.)

The R ₃ in the formula (4), which may have a substituent - (CH _{2) n} - alkylene chain represented by, which may have a substituent - (CH _{2) n} - Examples include an alkylene chain containing an ether bond such as O-. The n represents an integer from 0 to 10.

As a norbornene-based resin having a functional group capable of reacting with a norbornadiene derivative that changes its structure upon irradiation with light, a monomer represented by the above formula (3) and / or (4) and a monomer represented by the above formula (2) Are particularly preferred. Examples of the monovalent functional group that does not react with the norbornadiene derivative as R ₂ in Formula (2) include an alkyl group, a cycloalkyl group, and an aryl group. As a monomer represented by Formula (2), following formula (5) is preferable. By including the monomer represented by the formula (5) in the polymer, the heat resistance is improved, the structural change from the quadricyclane structure to the norbornadiene structure can be suppressed, and the long-term stability can be improved.

（式（５）中、ｍは０〜１０までの整数を示す。）

(In formula (5), m represents an integer from 0 to 10.)

  Examples of the norbornadiene derivative include 3-phenyl-2,5-norbornadiene-2-carboxylic acid, 3-phenoxy-2,5-norbornadiene-2-carboxylic acid, and 3-benzoyl-2,5-norbornadiene-2-carboxylic acid. 5-naphthyl-2,5-norbornadiene-2-carboxylic acid, 5-naphthoxy-2,5-norbornadiene-2-carboxylic acid, 5-naphthoyl-2,5-norbornadiene-2-carboxylic acid, 5-naphthyl- 2,5-norbornadiene-2-carboxylic acid or its acid halide, its ester, its metal salt, ammonium salt, etc. are mentioned.

  The glass transition temperature of the norbornene resin is not particularly limited, but is preferably 180 ° C. or higher, and particularly preferably 200 to 350 ° C. If the glass transition temperature is less than the lower limit, the heat resistance is reduced and the pattern is destroyed when the pattern is destroyed in the solder reflow process or the structure changes from the quadricyclane structure to the norbornadiene structure due to heat. . Further, when the upper limit is exceeded, flexibility may be lost.

  The norbornene-based resin skeleton is preferably a polymer in which a norbornane structure is substantially continuous (an addition polymer of norbornene). Thereby, heat resistance (especially glass transition temperature) can be improved and the structural change from a quadricyclane structure to a norbornadiene structure can be prevented.

The irradiation wavelength of light that brings about a structural change from the norbornadiene structure to the quadricyclane structure is preferably a wavelength region of 250 nm to 400 nm. When the wavelength is 250 nm or less, the resin film may be discolored.
A wavelength of 400 nm or more is insufficient in terms of energy to cause a photoisomerization reaction.

The difference in refractive index between the irradiated portion and the non-irradiated portion is not particularly limited, but is preferably 0.3 to 5.0%, particularly preferably 0.8 to 2.0%. If the difference in refractive index is less than the lower limit, the effect of transmitting light may be reduced, and if it exceeds the upper limit, a problem may occur in optical design.
The refractive index difference can be obtained by the following equation when the refractive index [A] of the irradiated portion and the refractive index [B] of the unirradiated portion are used.
Refractive index difference (%) = (A / B-1) × 100

As described above, the core portion 21 and the clad portion 22 can be formed on the resin film 2 (FIG. 1C).
The width of the core portion 21 is not particularly limited, but is preferably 5 to 100 μm, and particularly preferably 20 to 70 μm. In addition, in terms of optical characteristics and optical design, it is more desirable to design the optical waveguide so that the core width and the core height are the same.

Step B
In Step B, the optical waveguide 10 having the first cladding layer 3 and the second cladding layer 4 on both surfaces of the resin film 2 having the core portion 21 and the cladding portion 22 is manufactured.
First, the resin film 2 having the core portion 21 and the clad portion 22 formed on the substrate 1 is peeled off from the substrate 1 (FIG. 2A).
Next, the first cladding layer 3 and the second cladding layer 4 are bonded to the resin film 2.

The thickness of the first cladding layer 3 and the thickness of the second cladding layer 4 may be different, but are preferably the same. Thereby, the productivity of the optical waveguide can be improved. In addition, the occurrence of warpage of the optical waveguide can be reduced.
Although the thickness of the 1st clad layer 3 is not specifically limited, 5-500 micrometers is preferable and 50-200 micrometers is especially preferable. When the thickness is within the above range, the light confinement effect and the flexibility of the film are particularly excellent.

  Although the thickness of the 2nd clad layer 4 is not specifically limited, 5-500 micrometers is preferable and 50-200 micrometers is especially preferable. When the thickness is within the above range, the light confinement effect and the flexibility of the film are particularly excellent.

  The refractive index of the first cladding layer 3 is not particularly limited as long as it is lower than the refractive index with the core portion 21. Specifically, the difference between the refractive index of the first cladding layer 3 and the refractive index of the core portion 21 is preferably 0.3 to 10%, particularly preferably 0.8 to 5%. If the difference in refractive index is within the above range, it is equivalent to the difference in refractive index between the core portion 21 and the cladding portion 22 and is excellent in terms of optical design.

  The refractive index of the second cladding layer 4 is not particularly limited as long as it is lower than the refractive index with the core portion 21. Specifically, the difference between the refractive index of the second cladding layer 4 and the refractive index of the core portion 21 is preferably 0.3 to 10%, particularly preferably 0.8 to 5%. If the difference in refractive index is within the above range, the difference in refractive index between the core portion 21 and the cladding portion 22 is equivalent, and optical design becomes easy.

  The refractive index of the first cladding layer 3 and the refractive index of the second cladding layer 4 may be different, but are preferably the same. This facilitates optical design.

  Examples of the material constituting the first cladding layer 3 include norbornene resin, epoxy resin, acrylic resin, and the like. Of these, norbornene resins are preferred. Thereby, heat resistance, transparency, and flexibility can be improved.

  The norbornene-based resin used for the first cladding layer is preferably a norbornene addition polymer (homoaddition polymer). Thereby, heat resistance can be improved.

  Examples of the material constituting the second cladding layer 4 include norbornene-based resins, epoxy resins, acrylic resins, and the like. Of these, norbornene resins are preferred. Thereby, heat resistance, transparency, and flexibility can be improved.

  The norbornene-based resin used for the second cladding layer is preferably a norbornene addition polymer (homoaddition polymer). Thereby, heat resistance can be improved.

As a method for forming the first clad layer 3 and the second clad layer 4 on the resin film 2, for example, a spin coat method, a dipping method, a table coat method, a spray method, an applicator method, a curtain coat method, a die coat method, etc. The method is mentioned. Among these, the table coating method and the die coating method are preferable. Thereby, a resin film can be manufactured with high productivity.
Alternatively, the first clad layer 3 and the second clad layer 4 may be formed in advance as an uncured resin film, and may be joined to the resin film 2 by a method such as lamination.

  In Step B of the present embodiment, the case where the substrate 1 is peeled and used has been described, but the present invention is not limited to this. For example, when the substrate 1 that can function as a clad layer as described above is used, the clad layer may be formed only on one side of the resin film 2 (the side opposite to the substrate 1).

(Example)
EXAMPLES Hereinafter, although this invention is demonstrated in detail based on an Example and a comparative example, this invention is not limited to this.

1. Example of resin preparation As a norbornene-based resin having a norbornadiene structure whose structure is changed by light irradiation, an addition polymerization homopolymer of norbornene having a 3-glycidyloxymethyl group in a side chain and norbornene having no side chain and 3-phenyl- By reacting with 2,5-norbornadiene-2-carboxylic acid, pouring into methanol and precipitating the reaction product, separating and drying, norbornene resin (glass transition temperature (Tg) 300 ° C., weight average molecular weight) 70,000).

2. Production of Resin Film 96.00% by weight of norbornene resin obtained by the above method, 3.00% by weight of IRGANOX 1076 (manufactured by Ciba Specialty Chemicals) and IRGAFOS 168 (Ciba Specialty Chemicals) as an antioxidant 1.00 wt% was dissolved in mesitylene, applied onto a glass substrate by a bar coater method, and dried at 80 ° C. for 1 hour to obtain a resin film having a thickness of 50 μm.

3. Light irradiation Resin that covers the resin film with a photomask having a linear pattern with a width of 50 μm, and irradiates the resin film with ultraviolet rays using a high-pressure mercury lamp, with the irradiated portion serving as the cladding portion and the unirradiated portion serving as the core portion. A membrane was obtained.

4). Production of optical waveguide On both the upper and lower surfaces of the above-mentioned resin film, an addition polymerization homopolymer of norbornene having a butyl group in the side chain and norbornene having a triethoxysilyl group in the side chain (glass transition temperature (Tg) 280 ° C., An optical waveguide was obtained by forming a 50 μm thick clad layer having a weight average molecular weight of 100,000). The cladding layer was formed by a bar coater method.

The same procedure as in Example 1 was conducted except that the following norbornene-based resin having norbornadiene that undergoes structural change upon irradiation with light was used.
Addition of norbornene having 1,1,1,3,3,3-hexafluoro-2-hydroxy-isopropyl group in the side chain and norbornene having hexyl group in the side chain as norbornene resin having a side chain of norbornadiene structure It was obtained by synthesizing a polymerization homopolymer, reacting with 3-phenyl-2,5-norbornadiene-2-carboxylic acid, pouring the reaction solution into methanol, precipitating the reaction product, and separating and drying. A norbornene resin (Tg 280 ° C., weight average molecular weight 300,000) was used.

The same procedure as in Example 1 was conducted except that the following norbornene-based resin having norbornadiene that undergoes structural change upon irradiation with light was used.
As a norbornene resin having a side chain of norbornadiene structure, addition polymerization homopolymer of norbornene having 1,1,1,3,3,3-hexafluoro-2-hydroxy-isopropyl group in the side chain and norbornene having no side chain A norbornene system obtained by synthesizing a polymer, reacting with 3-phenyl-2,5-norbornadiene-2-carboxylic acid, pouring the reaction solution into methanol to precipitate the reaction product, and separating and drying Resin (Tg 310 ° C., weight average molecular weight 300,000) was used.

  The procedure was the same as Example 1 except that the thickness of the resin film was 150 μm.

  The procedure was the same as Example 1 except that the thickness of the resin film was 18 μm.

The following was used as the substrate and the cladding layer, and the same procedure as in Example 1 was performed except that the cladding layer was formed as follows.
A substrate in which a norbornene resin having a hexyl group (homoaddition polymer) (Tg 250 ° C., weight average molecular weight 300,000) having a thickness of 50 μm is formed on a glass substrate in advance is used.
In the production of an optical waveguide, a thickness composed of a norbornene resin (homoaddition polymer) having a hexyl group in the side chain only on the side opposite to the substrate of the resin film (Tg 250 ° C., weight average molecular weight 300,000). A 50 μm cladding layer was formed.

The same procedure as in Example 1 was performed except that the following resin was used as the cladding layer.
Arton (ring-opening polymer, manufactured by JSR, Tg 150 ° C.) was used as the norbornene-based resin.

The same procedure as in Example 1 was performed except that the following resin was used as the cladding layer.
An epoxy resin (manufactured by OPTOCAST3553-HM Electronic Materials Incorporated) was used instead of the norbornene resin.
After filtering through a 0.2 μm filter, it was applied to a substrate, placed in an oven at 65 ° C. for 2 hours, and thermally cured. The film thickness obtained was 50 μm.

(Comparative Example 1)
A copolymer was obtained by copolymerizing a monomer mixture consisting of glycidyl methacrylate and methyl methacrylate as a resin film whose structure changes upon irradiation with light according to a conventional method. Next, the obtained copolymer is reacted with 3-phenyl-2,5-norbornadiene-2-carboxylic acid, and the resulting reaction solution is poured into methanol to precipitate the reaction product, which is separated and dried. As a result, a norbornadiene-containing polymer was obtained. The obtained polymer was dissolved in chloroform, and this solution was applied onto a quartz substrate by a bar coater method, followed by vacuum drying at room temperature to form a thin film. After the thin film was masked, it was irradiated with ultraviolet rays using a high-pressure mercury lamp and an ultraviolet filter to obtain an optical waveguide having an irradiated portion made of a clad and an unirradiated portion made of a core. A clad layer having a thickness of 50 μm composed of a resin film made of polymethacrylate was also formed on both upper and lower surfaces of the resin film. The cladding layer was formed by a bar coater method.

(Comparative Example 2)
The following was used as a clad layer as a substrate, and the clad layer was formed as follows. As a substrate, an addition polymerization homopolymer of norbornene having a butyl group in the side chain and norbornene having a triethoxysilyl group in the side chain on a glass substrate (glass transition temperature (Tg) 280 ° C., weight average molecular weight 100,000) Was previously formed with a thickness of 50 μm.
A 50 μm-thick core layer composed of a norbornene resin (homoaddition polymer) having a hexyl group in the side chain (Tg 250 ° C., weight average molecular weight 300,000) was formed on the substrate by a bar coater method. An aluminum layer having a thickness of 0.3 μm was deposited on the core layer to form a mask layer. Further, a positive photoresist (diazonaphthoquinone-novolak resin system, manufactured by Tokyo Ohka Kogyo Co., Ltd., OFPR-800) was applied on the aluminum layer by spin coating, and then prebaked at about 95 ° C. Next, a photomask (Ti) for pattern formation is placed, irradiated with ultraviolet rays using an ultra-high pressure mercury lamp, and then a positive resist developer (TMAH: tetramethylammonium hydroxide aqueous solution, manufactured by Tokyo Ohka Kogyo Co., Ltd.) Development was performed using the name NMD-3). Thereafter, post-baking was performed at 135 ° C. As a result, a linear resist pattern having a line width of 8 μm was obtained. Next, the aluminum layer was wet etched to transfer the resist pattern to the aluminum layer. Further, the core layer was processed by dry etching using the patterned aluminum layer as a mask. Next, the aluminum layer was removed with an etching solution. From above, as an upper clad layer, an addition polymerization homopolymer (Tg 280 ° C., weight average molecular weight 100, with norbornene having a butyl group in the side chain and a norbornene having a triethoxysilyl group in the side chain similar to the lower clad layer. 000) to form an optical waveguide having a thickness of 50 μm.

The following evaluation was performed about the resin film and optical waveguide obtained by each Example and the comparative example. The evaluation items are shown together with the evaluation method. The obtained results are shown in Table 1.
1. Glass transition temperature (Tg) of optical waveguide
The Tg of the optical waveguide was evaluated in a tensile mode (temperature increase rate: 5 ° C./min) using TMA (TMA / SS120C manufactured by Seiko Instruments Inc.).

2. Refractive index difference between the core part and the clad part The refractive index between the core part and the clad part was evaluated by a prism coupling method (Model 2010 prism coupler manufactured by Metricon). The refractive index difference was evaluated from each refractive index based on the following formula.
Refractive index difference (%) = (refractive index of core / refractive index of cladding-1) × 100

3. Mechanical strength of optical waveguide The mechanical strength of the optical waveguide was evaluated according to JIS-K7127 for tensile strength.

4). Flexibility of Optical Waveguide The flexibility of the optical waveguide was evaluated based on the tensile elongation according to JIS-K7127.

5). Transparency of Optical Waveguide Transparency of the optical waveguide was evaluated by measuring transmittance using an ultraviolet / visible / infrared spectrophotometer (UV-3100, manufactured by Shimadzu Corporation).

6). Optical loss of optical waveguide The optical loss was evaluated by a method of measuring a length by cutting a single optical waveguide, that is, a so-called cutback method. The above method will be described in detail. An optical fiber is joined to both ends of one optical waveguide having a certain length, and light is inserted from one of the optical fibers. At that time, the amount of transmitted light is measured, and the optical waveguide is cut to shorten the length, and the amount of transmitted light is measured again. If the length before and after cutting is L ₁ and L ₂ [cm], and the transmitted light quantity is P ₁ and P ₂ , the optical loss is α = | 10 log (P ₁ / P ₂ ) / (L ₁ −L ₂ ) | It is expressed as [dB / cm]. Actually, cutting was performed a plurality of times, and the optical loss α was obtained from the slope of the log P vs. L graph.

7). Productivity of optical waveguide The productivity was evaluated based on the production man-hour of the optical waveguide obtained in Comparative Example 2 as a reference (100).

  As is clear from Table 1, Examples 1 to 8 were excellent in productivity and low in optical loss. Moreover, Examples 1-8 were excellent in intensity | strength, flexibility, and transparency. Moreover, Examples 1-6 were also shown to have a high glass transition temperature and excellent heat resistance.

FIG. 1 is a cross-sectional view showing a method of manufacturing an optical waveguide according to the present invention. FIG. 2 is a cross-sectional view showing a method for manufacturing an optical waveguide according to the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Board | substrate 2 Resin film 21 Core part 22 Clad part 3 1st clad layer 4 2nd clad layer 10 Optical waveguide 11 Light 12 Masking

Claims (11)

A method for producing an optical waveguide comprising a step of irradiating a resin film comprising a resin composition containing a norbornene-based resin with light to form an optical waveguide,
The norbornene-based resin has a norbornadiene structure whose structure is changed by light irradiation. A resin film composed of a resin composition containing a norbornene resin is irradiated with light in a predetermined pattern to change the resin structure in the resin film, thereby providing a difference in refractive index between the irradiated part and the non-irradiated part. A method of manufacturing an optical waveguide having a step of forming an optical waveguide by:
The norbornene-based resin has a norbornadiene structure whose structure is changed by light irradiation.   The method for producing an optical waveguide according to claim 1, wherein the norbornene-based resin skeleton has a substantially norbornane structure continuously polymerized. The norbornene-based resin is obtained by reacting a norbornadiene derivative with a side chain of a polymer containing a monomer represented by the following formula (1) having a functional group capable of reacting with a norbornadiene derivative. Item 4. A method for manufacturing an optical waveguide according to any one of Items 1 to 3.

(In formula (1), R ₁ represents a monovalent functional group capable of reacting with a norbornadiene derivative.) The monomer represented by the formula (1) is at least one monomer having a monovalent group composed of an epoxy group or a hydroxyl group as R ₁ in the formula (1). The manufacturing method of the optical waveguide of description. The polymer is obtained by polymerizing a monomer represented by the above formula (1) having a functional group capable of reacting with a norbornadiene derivative and a monomer represented by the following formula (2). Or the manufacturing method of the optical waveguide of 5.

(In formula (2), R ₂ represents a monovalent functional group that does not react with the norbornadiene derivative.)   The method for manufacturing an optical waveguide according to claim 1, wherein the norbornene-based resin has a glass transition temperature of 180 ° C. or higher.   The method for producing an optical waveguide according to any one of claims 1 to 7, wherein a content of the norbornene-based resin is 50 to 99.5% by weight of the entire resin composition.   The method for manufacturing an optical waveguide according to claim 1, wherein a glass transition temperature of the resin film is 180 ° C. or higher.   The method for manufacturing an optical waveguide according to claim 1, wherein the resin film has a thickness of 5 to 100 μm.   An optical waveguide obtained by the method for manufacturing an optical waveguide according to claim 1.

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