JP2005128513A - Manufacturing method of optical waveguide, and optical waveguide - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical waveguide manufacturing method providing an optical waveguide which is excellent in productivity and has low optical losses, and also to provide an optical waveguide. <P>SOLUTION: The manufacturing method of an optical waveguide of this invention includes a process for forming an optical waveguide by emitting electron rays to a resin film formed of a resin composition containing a norbornene series resin, and the norbornene series resin has a side chain which is changed in structure by being irradiated with the electron rays. The manufacturing method of the optical waveguide also includes a process for forming an optical waveguide by emitting electron rays in a predetermined pattern to a resin film formed of a resin composition containing a norbornene series resin to cross-link the irradiated part of the resin film and by making a refractive index difference between the irradiated part and the non-irradiated part. The norbornene series resin has a side chain cross-link reacting by irradiation of electron rays. Moreover, the optical waveguide of this invention is attained by the manufacturing method of the optical waveguide described above. <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.
A conventional optical waveguide type device uses a silica-based optical waveguide.
However, since the quartz optical waveguide is made of quartz glass, it is fragile and requires a vacuum process such as a high-temperature process or reactive ion etching.

On the other hand, many polymer optical waveguides have been made as alternatives to quartz optical waveguides.
In conventional polymer waveguides, a relief pattern of a waveguide pattern is formed by forming a pattern with a photosensitive resin on a polyimide layer, for example, and etching with RIE (Reactive Ion Etching). For example, a method of peeling the functional resin is used (see, for example, 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.

JP 05-164929 A

The objective of this invention is providing the manufacturing method of the optical waveguide which can provide the optical waveguide which is excellent in productivity and has small optical loss.
Another object of the present invention is to provide an optical waveguide with small optical loss.

（６）前記ノルボルネン系樹脂のガラス転移温度は、１８０℃以上である上記（１）ないし（５）のいずれかに記載の光導波路の製造方法。
（７）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５０〜１００重量％である上記（１）ないし（６）のいずれかに記載の光導波路の製造方法。
（８）前記電子線の加速電圧は、１００［ＫＶ］以下である上記（１）ないし（７）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℃以上である上記（１）ないし（８）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である上記（１）ないし（９）のいずれかに記載の光導波路の製造方法。
（１１）光導波路を使用する光の波長における前記照射部と未照射部との屈折率差は、０．３〜５．０％である上記（２）ないし（１０）のいずれかに記載の光導波路の製造方法。
（１２）前記樹脂膜は、基板の少なくとも片面側に形成されるものである上記（１）ないし（１１）のいずれかに記載の光導波路の製造方法。
（１３）前記基板は、その全部または一部がクラッド層として作用するものである上記（１２）に記載の光導波路の製造方法。
（１４）上記（１）ないし（１３）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 (14).
(1) A method for producing an optical waveguide comprising a step of irradiating an electron beam onto a resin film composed of a resin composition containing a norbornene-based resin to form an optical waveguide, wherein the norbornene-based resin is an electron beam A method for producing an optical waveguide, comprising a side chain whose structure changes upon irradiation.
(2) A resin film composed of a resin composition containing a norbornene-based resin is irradiated with an electron beam in a predetermined pattern to crosslink the irradiated portion of the resin film, and the irradiated portion and the unirradiated portion have a refractive index. A method for producing an optical waveguide, comprising the step of forming an optical waveguide by providing a difference between the norbornene-based resin and the norbornene-based resin having a side chain that undergoes a crosslinking reaction upon irradiation with an electron beam. Method.
(3) The method for producing an optical waveguide according to (1) or (2), wherein the side chain undergoing a crosslinking reaction has a carbon chain.
(4) The method for producing an optical waveguide according to any one of (1) to (3), wherein the norbornene-based resin skeleton is a polymer in which a norbornane structure is substantially continuously polymerized.
(5) The light according to any one of (1) to (4), wherein the norbornene-based resin is obtained by polymerizing at least one monomer of the following formulas (1) to (3). A method for manufacturing a waveguide.

(6) The method for producing an optical waveguide according to any one of (1) to (5), wherein the glass transition temperature of the norbornene-based resin is 180 ° C. or higher.
(7) The method for producing an optical waveguide according to any one of (1) to (6), wherein the content of the norbornene-based resin is 50 to 100% by weight of the entire resin composition.
(8) The method of manufacturing an optical waveguide according to any one of (1) to (7), wherein an acceleration voltage of the electron beam is 100 [KV] or less.
(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) The refractive index difference between the irradiated part and the non-irradiated part at the wavelength of light using the optical waveguide is 0.3 to 5.0% according to any one of (2) to (10) above. Manufacturing method of optical waveguide.
(12) The optical waveguide manufacturing method according to any one of (1) to (11), wherein the resin film is formed on at least one side of the substrate.
(13) The method for manufacturing an optical waveguide according to (12), wherein all or a part of the substrate acts as a cladding layer.
(14) An optical waveguide obtained by the method for manufacturing an optical waveguide according to any one of (1) to (13).

According to the present invention, an optical waveguide with small optical loss can be obtained.
In addition, when a norbornene-based resin having a substantially continuous norbornane structure is used, the heat resistance is particularly excellent.
In addition, when a norbornene-based resin having a side chain that undergoes a crosslinking reaction upon irradiation with an electron beam is used, the difference in the refractive index of the resin film can be particularly increased, particularly in the properties such as weather resistance and chemical resistance of the optical waveguide. Excellent.
Further, when the electron beam to be irradiated is set to 100 [KV] or less, the refractive index difference can be particularly increased without damaging the substrate or the like.
Further, according to the present invention, the optical waveguide can be manufactured with high productivity.

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 comprising a step of forming an optical waveguide by irradiating a resin film comprising a resin composition containing a norbornene-based resin with an electron beam. The system resin has a side chain whose structure changes upon irradiation with an electron beam.
The method for producing an optical waveguide according to the present invention includes irradiating a resin film composed of a resin composition containing a norbornene-based resin with an electron beam in a predetermined pattern to cross-link an irradiation part of the resin film. And a non-irradiated portion to provide a difference in refractive index to form an optical waveguide, wherein the norbornene-based resin has a side chain that undergoes a crosslinking reaction upon irradiation with an electron beam. It is a feature.
The optical waveguide of the present invention is obtained by the method for manufacturing an optical waveguide described above.

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.

The norbornene-based resin has a side chain whose structure is changed by an electron beam as described later. Thereby, the refractive index of an irradiation part can be changed by electron beam irradiation.
Examples of the norbornene-based resin include ring-opening polymers obtained by ring-opening polymerization of norbornene, copolymers of norbornene and other monomers such as ethylene, norbornene addition polymers (including norbornene homoaddition polymers) Etc.

  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, the electron beam 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 film 2 may be formed by bonding an uncured resin film made 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 the electron beam 11 is irradiated (FIG. 1B). Thereby, the core part 21 can be formed in the part irradiated with the electron beam 11.
The reason why the core portion 21 is formed in the resin film 2 by irradiation with the electron beam 11 is as follows.
The norbornene-based resin has a side chain whose structure changes with the electron beam 11 as described above. For this reason, the structure of the norbornene-based resin in the portion irradiated with the electron beam 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 portion irradiated with the electron beam 11 and the non-irradiated portion.
Examples of the method for performing the masking 12 include a stencil mask and a method such as vapor deposition of a metal film. Among these, a method using a stencil mask is preferable. Thereby, productivity can be improved.

  The structural change by the electron beam 11 includes, for example, a crosslinking reaction, a decomposition reaction, and the like. Among these, a case where a crosslinking reaction is caused by irradiation with the electron beam 11 is preferable. Thereby, the difference in refractive index can be increased. Therefore, the norbornene-based resin preferably has a side chain that undergoes a crosslinking reaction upon irradiation with the electron beam 11.

Specifically, the reason why the refractive index changes due to the structural change of the norbornene resin due to the crosslinking reaction is as follows.
Irradiation with the electron beam 11 causes a cross-linking reaction in the side chain of the norbornene resin in the irradiated part. The norbornene-based resin in which the crosslinking reaction has occurred has a high density and a high refractive index because the free volume is reduced.
Therefore, the refractive index of the portion irradiated with the electron beam 11 is increased, and the core portion 21 of the optical waveguide is formed, and the non-irradiated portion forms the cladding portion 22.

Further, the reason why the refractive index changes due to the structural change of the norbornene resin due to the decomposition reaction is as follows.
For example, in a norbornene-based resin having a fluorine atom in the side chain, the side chain is decomposed by irradiation with the electron beam 11, and the fluorine atom is released. When fluorine atoms are released, the molecular refraction increases and the refractive index increases because the molecular volume decreases. Therefore, the refractive index of the portion irradiated with the electron beam 11 is increased, and the core portion 21 of the optical waveguide is formed, and the non-irradiated portion forms the cladding portion 22.
Conversely, for example, a norbornene-based resin having a halogen atom other than a fluorine atom is decomposed by irradiation with the electron beam 11, and the halogen atom is released. When halogen atoms are released, the refractive index decreases due to a decrease in molecular refraction. Therefore, the refractive index of the portion irradiated with the electron beam 11 is lowered, and the cladding portion 22 of the optical waveguide is formed, and the unirradiated portion forms the core portion 21.
Depending on the structure of the side chain thus decomposed, whether the refractive index of the portion irradiated with the electron beam 11 (decomposed portion) is high or low is different.

  The norbornene-based resin having a side chain that undergoes a crosslinking reaction upon irradiation with the electron beam 11 is preferably one having a carbon chain, and specifically has at least one alkyl group (particularly a linear alkyl group) in the side chain. Mention may be made of norbornene resins. Specific examples of the alkyl group include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, a pentyl group, a hexyl group, a heptyl group, an octyl group, a nonyl group, and a decyl group. Moreover, a part of hydrogen of the alkyl group may have another substituent. Specific examples of the substituent include a hydroxy group, an alkoxy group (for example, a methoxy group, an ethoxy group, a propoxy group, and a butoxy group), an alkoxysilane group, an ether group, a ketone group, an ester group, and an amino group.

  Examples of the alkoxysilane group include trimethoxysilane, triethoxysilane, methyldimethoxysilane, dimethylmethoxysilane, methyldiphenyl, dimethylphenyl, triphenyl, ethyldiphenyl, and diethylphenyl.

More specifically, the norbornene-based resin having a side chain that undergoes a crosslinking reaction upon irradiation with the electron beam 11 is preferably obtained by polymerizing a monomer represented by the following formula (4).

Among norbornene resins having a side chain that undergoes a crosslinking reaction upon irradiation with the electron beam 11, those obtained by polymerizing at least one monomer of the following formulas (1) to (3) are more preferable. Thereby, decomposition | disassembly by the electron beam 11 can be suppressed, coloring of a film can be suppressed, and long-term stability can be improved. Particularly preferred are those obtained by copolymerization of two or more of the monomers described in formulas (1) to (3) (including homoaddition polymerization of norbornene-based resins). In particular, the formulas (1) and (3) are co-polymerized. Those obtained by polymerization are preferred. Thereby, adhesiveness can be improved.

Examples of the norbornene-based resin having a side chain that undergoes a decomposition reaction upon irradiation with the electron beam 11 include those in which the alkyl group in the side chain has a branched structure. Specific examples of the alkyl group having a branched structure include an isobutyl group, a tert-butyl group, a dimethylpentyl group, a dimethylhexyl group, and a dimethylheptyl group.
In addition, in the alkyl group having the branched structure, part or all of the hydrogen thereof may have a substituent. Specific examples of the substituent include a halogen group, a hydroxy group, an alkoxy group (for example, a methoxy group, an ethoxy group, a propoxy group, and a butoxy group), an alkoxysilane group, an ether group, a ketone group, an ester group, and an amino group. It is done.

The difference in refractive index between the irradiated portion of the electron beam 11 and the unirradiated 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. If the difference is higher than the upper limit, there is a large possibility that an excessive decomposition reaction has occurred and long-term stability is reduced. There is a case.
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

  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 may be reduced and the pattern may be destroyed in the solder reflow process. If the glass transition temperature exceeds the upper limit, flexibility may be lost.

  The norbornene-based resin skeleton is not particularly limited, but is preferably a polymer in which a norbornane structure is continuously polymerized (norbornene addition polymer). Thereby, heat resistance (especially glass transition temperature) can be improved.

Although the acceleration voltage of the electron beam 11 is appropriately determined depending on the thickness of the resin film 2, it is preferably 100 [KV] or less, particularly preferably 50 to 80 [KV].
If the acceleration voltage is less than the lower limit value, the effect of changing the refractive index by a crosslinking reaction may be reduced, and if the acceleration voltage exceeds the upper limit value, the irradiation of the electron beam 11 may be excessive.
Conventionally, the acceleration voltage of the electron beam 11 was about 200 [KV]. In this case, the resin constituting the conventional resin film 2 may cause excessive decomposition reaction or damage the substrate 1 due to excessive irradiation. On the other hand, in the present invention, since the norbornene resin as described above is used as the resin constituting the resin film 2, the structure of the resin constituting the resin film 2 is changed even with the electron beam 11 having a relatively low acceleration voltage. It becomes possible to make it. Accordingly, the structure of the norbornene-based resin can be changed even with the electron beam 11 having a relatively low acceleration voltage of 100 [KV] or less.

  The irradiation amount of the electron beam 11 is not particularly limited, but is preferably 50 to 2,000 [KGy], and particularly preferably 100 to 1,000 [KGy]. If the irradiation amount is less than the lower limit value, the structure of the side chain of the norbornene resin may not be sufficiently changed, and if the irradiation amount exceeds the upper limit value, irradiation may be excessive and adverse effects may occur. For example, deterioration or alteration may occur.

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 10 can be improved. Further, the occurrence of warpage of the optical waveguide 10 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.

  Examples of the norbornene-based resin include a ring-opening polymer obtained by ring-opening polymerization of norbornene, a copolymer of norbornene and another monomer such as ethylene, and an addition polymer of norbornene. Among these, norbornene addition polymers (homoaddition polymers) are preferred. 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.

  Examples of the norbornene-based resin include ring-opening polymers obtained by ring-opening polymerization of norbornene, copolymers of norbornene and other monomers such as ethylene, norbornene addition polymers (particularly norbornene homoaddition polymers). Etc. Among these, norbornene addition polymers (homoaddition polymers) are preferred. 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 coat method and the die coat 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).
In Step B, the case where the portion irradiated with the electron beam 11 is the core portion 21 has been described, but the present invention is not limited to this. For example, the electron beam irradiation part may form the clad part 22.

  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. Production of resin film As norbornene-based resin having a side chain whose structure is changed by electron beam irradiation, an addition polymerization homopolymer (glass transition temperature) of norbornene having a butyl group in the side chain and norbornene having a triethoxysilyl group in the side chain (Tg) 280 ° C., weight average molecular weight 100,000) was synthesized, and 96.00 wt% and antioxidant 4.00 wt% were dissolved in mesitylene and coated on 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.

2. Electron beam irradiation The resin film is covered with a stencil mask having a linear pattern with a width of 50 μm, and an electron beam is irradiated (1,000 KGy) at an acceleration voltage of 55 [KV] using Min-Eb Labo SCAN (manufactured by USHIO). Thus, a resin film was obtained in which the irradiated part was the core part and the non-irradiated part was the cladding part.

3. 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., (Weight average molecular weight 100,000) was synthesized, and a clad layer having a thickness of 50 μm formed therefrom was formed to obtain an optical waveguide. The clad 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 a side chain whose structure was changed by electron beam irradiation was used.
A norbornene resin having a hexyl group in the side chain (homoaddition polymer) (Tg 280 ° C., weight average molecular weight 300,000) was synthesized and used as a norbornene-based resin having a side chain that undergoes a crosslinking reaction.

The same procedure as in Example 1 was conducted except that the following norbornene-based resin having a side chain whose structure was changed by electron beam irradiation was used.
Arton (ring-opening polymer, manufactured by JSR, Tg 150 ° C.) was used as a norbornene-based resin having a side chain that undergoes a crosslinking reaction.

The same procedure as in Example 1 was performed except that the norbornene-based resin having a side chain that undergoes a decomposition reaction by electron beam irradiation described below was used as the norbornene-based resin having a side chain whose structure is changed by electron beam irradiation.
A norbornene resin having a hexachloroisopropyl group (homoaddition polymer) (Tg 300 ° C., weight average molecular weight 1,500,000) was synthesized and used as a norbornene resin having a side chain that undergoes a decomposition reaction.

  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 acceleration voltage of electron beam irradiation was the same as that of Example 1 except that it was changed as follows.
The acceleration voltage was set to 100 (KV) (1,000 KGy) using a low acceleration voltage type electron beam irradiation apparatus Alite beam (manufactured by Iwasaki Electric Co., Ltd.).

The following was used as a clad layer as a substrate, and the same procedure as in Example 1 was performed except that the clad layer was formed as follows.
A substrate in which a norbornene resin having a hexyl group (homoaddition polymer) (Tg 280 ° 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 280 ° 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 2 was performed except that the following resin was used as the cladding layer.
Instead of the norbornene-based resin, an epoxy resin (OPTOCAST3553-HM Electoronic Materials Incorporated) was used.
After filtering with a 0.2 μm filter, it was applied to the substrate by a bar coater method, exposed to 1000 mJ / cm ² with a UV irradiation device, put in an oven at 120 ° C. for 20 minutes, and thermally cured. The film thickness obtained was 50 μm.

The same procedure as in Example 1 was performed except that a norbornene-based resin having a side chain that undergoes a norbornene-based crosslinking reaction and a side chain that undergoes a decomposition reaction was used as the norbornene-based resin having a side chain whose structure is changed by electron beam irradiation.
Synthesis of a norbornene having a hexyl group having a side chain that undergoes a cross-linking reaction and a norbornene addition polymer homopolymer having a hexafluoroisopropyl group having a side chain that undergoes a decomposition reaction (Tg 300 ° C., weight average molecular weight 1,200,000) Was used.
(Comparative Example 1)

The same procedure as in Example 1 was performed except that polystyrene (G210, manufactured by Toyo Styrene Co., Ltd., Tg 100 ° C.) was used as the resin constituting the resin film.
(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 280 ° 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, and after irradiation with ultraviolet rays using an ultrahigh pressure mercury lamp, a positive resist developer (TMAH: tetramethylammonium hydroxide aqueous solution, manufactured by Tokyo Ohka Kogyo Co., Ltd., Development was performed using 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 and the cladding The refractive index between the core and the cladding of the resin film 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 The transparency of the optical waveguide was evaluated by measuring the 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 , L ₂ [cm], and the amount of transmitted light 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 apparent from Table 1, Examples 1 to 11 were excellent in productivity and low in optical loss.
Examples 1 to 11 were also excellent in transparency, strength and flexibility.
In addition, Examples 1, 2, 4 to 8 and 11 were 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 Electron beam 12 Masking

Claims (14)

A method for producing an optical waveguide comprising a step of irradiating an electron beam onto a resin film composed of a resin composition containing a norbornene-based resin to form an optical waveguide,
The method of manufacturing an optical waveguide, wherein the norbornene-based resin has a side chain whose structure is changed by irradiation with an electron beam. A resin film composed of a resin composition containing a norbornene resin is irradiated with an electron beam in a predetermined pattern to crosslink the irradiated part of the resin film, and a difference in refractive index between the irradiated part and the unirradiated part is given. A method of manufacturing an optical waveguide having a step of forming an optical waveguide by providing,
The method of manufacturing an optical waveguide, wherein the norbornene-based resin has a side chain that undergoes a crosslinking reaction upon irradiation with an electron beam.   The method of manufacturing an optical waveguide according to claim 1, wherein the side chain that undergoes the crosslinking reaction has a carbon chain.   4. The method of manufacturing an optical waveguide according to claim 1, wherein the norbornene-based resin skeleton is a polymer in which a norbornane structure is substantially continuously polymerized. The method for producing an optical waveguide according to claim 1, wherein the norbornene-based resin is obtained by polymerizing at least one monomer selected from the following formulas (1) to (3).

  The method for producing an optical waveguide according to claim 1, wherein a glass transition temperature of the norbornene-based resin is 180 ° C. or higher.   The method for producing an optical waveguide according to claim 1, wherein the content of the norbornene-based resin is 50 to 100% by weight of the entire resin composition.   The method of manufacturing an optical waveguide according to claim 1, wherein an acceleration voltage of the electron beam is 100 [KV] or less.   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.   The method for manufacturing an optical waveguide according to any one of claims 2 to 10, wherein a difference in refractive index between the irradiated portion and the unirradiated portion at a wavelength of light using the optical waveguide is 0.3 to 5.0%.   The method for manufacturing an optical waveguide according to claim 1, wherein the resin film is formed on at least one side of the substrate.   The method for manufacturing an optical waveguide according to claim 12, wherein all or a part of the substrate acts as a cladding layer.   An optical waveguide obtained by the method for manufacturing an optical waveguide according to claim 1.

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