JP2003286346A - Optical waveguide and plastic material therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a plastic material for an optical waveguide having excellent electric properties, heat resistance and transparency and capable of forming a waveguide of a wide surface area at a low cost. <P>SOLUTION: The plastic material for an optical waveguide useful for optical communication comprises a polybenzoxazole resin having a structure formed by ring-closure of a polybenzoxazole precursor containing a repeating unit of general formula (1) (wherein m and n are each an integer fulfilling m>0, n≥0, 2≤m+n≤1000 and 0.05≤m/(m+n)≤1; R<SB>1</SB>to R<SB>4</SB>are each hydrogen or a monovalent organic group; X is a group selected from a structure shown by the equation B; and Y is a group selected from a structure shown by the equation C). <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plastic optical waveguide material and an optical waveguide. More specifically, for plastic optical waveguides suitable for interconnection and optical communication devices, etc. using a plastic optical waveguide that couples laser light to heat resistance, electrical characteristics, mechanical characteristics, physical characteristics, especially optical characteristics with low loss. The present invention relates to a material and an optical waveguide using the same.

[0002]

2. Description of the Related Art Conventionally, materials such as glass (quartz) and plastic have been studied as optical waveguide materials.
Among them, the optical waveguide made of quartz has advantages such as low loss and high heat resistance, and therefore, it has been extensively studied and actually used in the fields of optical fibers, optical interconnections and optical communication devices.

On the other hand, an optical waveguide made of plastic is easier to manufacture and has a larger area than a quartz optical waveguide, and a plastic optical waveguide using a polymer such as polymethylmethacrylate, polycarbonate and an ultraviolet curable resin is considered. Has been done.

[0004]

However, in the above-mentioned conventional quartz optical waveguide, it is essentially difficult to reduce the cost because it takes a long process to manufacture. Further, since a high heat treatment of about 1000 ° C. is required in the manufacturing process, there is a problem that the fusion with the electric circuit board is poor and it is difficult to increase the area.

Further, a plastic optical waveguide made of polymethacrylate, polycarbonate or polystyrene has a large number of aliphatic C—H bonds in its molecular chain, so that there is a large absorption in the near infrared region, which is a communication field. Difficult to apply to wavelength. Since the heat resistance of the constituent material is around 100 ° C., the usage environment is limited, and it is necessary to pass through a soldering process of several hundreds of degrees in order to be incorporated as a mounting circuit, and the compatibility with an electric circuit board is not achieved. There was a problem of getting worse.

[0006] Moreover, although it is a plastic material,
Some attempts have been made to use polyimide having a heat resistance of 0 ° C. or higher for a plastic optical waveguide,
Due to its unique molecular structure, the current polyimide has a problem that the optical loss due to the absorption due to the structure is extremely large and is not suitable for an optical waveguide. In the case of a polyimide resin, which has a high crystallinity due to its structure and has a small film thickness, there is little effect, but when the film thickness used for the waveguide is reached, the film becomes brittle due to its high crystallinity. Or, the refractive index may change.

Further, polybenzoxazole, which is superior in heat resistance to polyimide, is used in the optical communication wavelength band of 1.3 μm.
When used with 1.55 μm or 1.5 μm, the conventional polybenzoxazole has large absorption at this wavelength and is difficult to apply.

Therefore, the present invention is to provide a material for a plastic optical waveguide, which is excellent in electrical characteristics, heat resistance, particularly transparency, and which can realize a large area at a low cost.

[0009]

DISCLOSURE OF THE INVENTION The inventors of the present invention have made earnest studies in view of the above-mentioned conventional problems, and as a result, they have a polybenzoxazole resin having a structure in which a polybenzoxazole precursor having a specific structure is ring-closed. The inventors have found a material for a plastic optical waveguide for optical communication characterized by the above, and completed the present invention.

That is, the present invention is as follows: A plastic optical waveguide material comprising a polybenzoxazole resin obtained by ring-closing a polybenzoxazole precursor having a structure represented by the general formula (A), and

[Chemical 5] (However, m and n in the formula are m> 0, n ≧ 0, and 2 ≦ m.
+ N ≦ 1000, and 0.05 ≦ m / (m + n) ≦ 1
Is an integer that satisfies. R _{1 to} R ₄ represent a hydrogen atom or a monovalent organic group, X is a tetravalent group selected from the groups represented by formula (B), and Y ₁ and Y ₂ are represented by the formula (C ) A divalent group selected from the groups represented by )

[0011]

[Chemical 6]

[0012]

[Chemical 7] (However, in the formula (B) and the formula (C), X ₁ and X ₂ are the formula (D).
A divalent group selected from the groups represented by Also,
I, j, and k in the formula (C) each represent an integer of 2 to 10. In the structures represented by the formulas (B) and (C), the hydrogen atom on the benzene ring is a methyl group, an ethyl group,
It may be substituted with at least one group selected from propyl group, isopropyl group, butyl group, isobutyl group, t-butyl group, fluorine atom, trifluoromethyl group and chlorine atom. )

[0013]

[Chemical 8]

2. An optical waveguide comprising a core layer formed of the plastic optical waveguide material according to item 1.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION The polybenzoxazole precursor used in the present invention has a structure represented by the general formula (A), and is a tetravalent group represented by the general formula (B). By using at least one bisaminophenol compound having any of the following and at least one dicarboxylic acid having any of the divalent groups represented by the formula (C), a conventional acid chloride method, activity Esterification method or condensation reaction in the presence of a dehydrating condensation agent such as polyphosphoric acid or dicyclohexylcarbodiimide.

Examples of the bisaminophenol compound having a tetravalent group represented by the formula (B) used in the present invention include bis (4-amino-3-hydroxyphenyl) ether and bis (3-amino-4-). Hydroxyphenyl) ether,
Bis (4-amino-3-methoxyphenyl) ether,
Bis (3-amino-4-methoxyphenyl) ether,
Bis (3-amino-4-hydroxyphenyl) sulfide, bis (4-amino-3-hydroxyphenyl) sulfide, bis (3-amino-4-methoxyphenyl) sulfide, bis (4-amino-3-methoxyphenyl)
Sulfide, bis (3-amino-4-hydroxyphenyl) ketone, bis (4-amino-3-hydroxyphenyl) ketone, bis (3-amino-4-methoxyphenyl) ketone, bis (4-amino-3-methoxy) Phenyl) ketone, bis (3-amino-4-hydroxyphenyl) sulfone, bis (4-amino-3-hydroxyphenyl) sulfone, bis (3-amino-4-methoxyphenyl) sulfone, bis (4-amino-3) -Methoxyphenyl) sulfone, 2,2-bis (3-amino-4-hydroxyphenyl) propane, 2,2-bis (4-amino-3-hydroxyphenyl) propane, 2,2-bis (3-amino- 4-methoxyphenyl) propane, 2,
2-bis (4-amino-3-methoxyphenyl) propane, bis (3-amino-4-hydroxyphenyl) methane, 2,2-bis (4-amino-3-hydroxyphenyl) methane, bis (3-amino -4-Methoxyphenyl) methane, 2,2-bis (4-amino-3-methoxyphenyl) methane, 2,2-bis (4-amino-3-hydroxyphenyl) hexafluoropropane, 2,2-
Bis (3-amino-4-hydroxyphenyl) hexafluoropropane, 2,2-bis (4-amino-3-methoxyphenyl) hexafluoropropane, 2,2-bis (3-amino-4-methoxyphenyl) hexa Fluoropropane, 9,9-bis (4-((4-amino-3-hydroxy) phenoxy) phenyl) fluorene, 9,9
-Bis (4-((3-amino-4-hydroxy) phenoxy) phenyl) fluorene, 9,9-bis (4-
((4-amino-3-methoxy) phenoxy) phenyl) fluorene, 9,9-bis (4-((3-amino-
4-methoxy) phenoxy) phenyl) fluorene,
9,9-bis-((4-amino-3-hydroxy) phenyl) fluorene, 9,9-bis-((3-amino-4
-Hydroxy) phenyl) fluorene, 9,9-bis-
((4-Amino-3-methoxy) phenyl) fluorene, 9,9-bis-((3-amino-4-methoxy) phenyl) fluorene, 9,9-bis (4-((4-amino-3-) Hydroxy) phenoxy) -3-phenyl-phenyl) -fluorene, 9,9-bis (4-((3-amino-4-hydroxy) phenoxy) -3-phenyl-
Phenyl) -fluorene, 9,9-bis (4-((4-
Amino-3-methoxy) phenoxy) -3-phenyl-
Phenyl) -fluorene, 9,9-bis (4-((3-
Amino-4-methoxy) phenoxy) -3-phenyl-
Phenyl) -fluorene, 9,9-bis-((2-amino-3-hydroxy-4-phenyl) -phenyl) -fluorene, 9,9-bis-((2-hydroxy-3-amino-4-phenyl) ) -Phenyl) -fluorene, 9,
9-bis-((2-amino-3-methoxy-4-phenyl) -phenyl) -fluorene, 9,9-bis-((2
-Methoxy-3-amino-4-phenyl) -phenyl)
Examples thereof include, but are not limited to, fluorene and the like, and derivatives thereof such as ester compounds and ether compounds. These bisaminophenol compounds can be used alone or in combination.

The dicarboxylic acid having a divalent group represented by the formula (C) used in the present invention includes 4,4'-oxybisbenzoic acid, 3,3'-oxybisbenzoic acid and 3,4 '.
-Oxybisbenzoic acid, 2,4'-oxybisbenzoic acid, 3,4'-oxybisbenzoic acid, 2,3'-oxybisbenzoic acid, 2,2-bis (4-carboxyphenyl) -hexafluoropropane, bis ( 4-carboxyphenyl) -sulfide, bis (4-carboxyphenyl) -sulfone, bis (4-carboxyphenyl) -methane, 2,2-bis (4-carboxyphenyl) -propane, bis (4-carboxyphenyl)- Ketone, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, 1,9-nonanedicarboxylic acid, dodecanedioic acid, tridecanedioic acid, 1,12-dodecanedicarboxylic acid, tetrafluorosuccinic acid Acid, hexafluoroglutaric acid, octafluoroadipic acid, perfluoropimelic acid, per Ruorosuberin acid, perfluoro azelaic acid, perfluoro sebacic acid, 1,9
-Perfluorononanedicarboxylic acid, perfluorododecanedioic acid, perfluorotridecanedioic acid, 1,12-perfluorododecanedicarboxylic acid, tetrachlorosuccinic acid, hexachloroglutaric acid, octachloroadipic acid, perchloropimelic acid, par Chlorosuberic acid, perchloroazelaic acid, perchlorosebacic acid, 1,9
-Perchlorononanedicarboxylic acid, perchlorododecanedioic acid, perchlorotridecanedioic acid, 1,12-perchlorododecanedicarboxylic acid, 1,4-perfluorocyclohexanedicarboxylic acid, 1,3-perfluorocyclohexanedicarboxylic acid, 1,2-perfluorocyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid, 1,4-perchlorocyclohexanedicarboxylic acid, 1,3-perchloro Examples thereof include, but are not limited to, cyclohexanedicarboxylic acid and 1,2-perchlorohexanedicarboxylic acid. These dicarboxylic acids can be used alone or in combination.

Among the methods for producing the polybenzoxazole precursor used in the present invention, an example of synthesis by the acid chloride method is given. First, the dicarboxylic acid is added in an excess amount in the presence of a catalyst such as N, N-dimethylformamide. With thionyl chloride,
The reaction is carried out at room temperature to 75 ° C., and excess thionyl chloride is distilled off by heating and reducing pressure. Then, the residue is recrystallized with a solvent such as hexane to obtain dicarboxylic acid chloride which is an acid chloride. Then, the bisaminophenol compound is usually dissolved in a polar solvent such as N-methyl-2-pyrrolidone and reacted with dicarboxylic acid chloride in the presence of an acid acceptor such as pyridine at −30 ° C. to room temperature. Thus, the polybenzoxazole precursor can be obtained.

In the present invention, the polybenzoxazole resin can be obtained by subjecting the polybenzoxazole precursor thus obtained to a ring-closing reaction by heating or treating with a dehydrating agent as in the conventional method. If necessary, a surfactant, a coupling agent, or the like can be added to the polybenzoxazole precursor or resin as various additives for use.

Further, the precursor of the polybenzoxazole resin in the present invention is represented by R _{1 to} R ₄ in the general formula (A).
When at least one of the above is hydrogen, by using together with a naphthoquinonediazide compound as a photosensitizer,
As a positive type photosensitive resin composition, in the general formula (A), when at least one of R _{1 to} R ₄ is a group having a photocrosslinkable group such as a methacryloyl group, a photoinitiator is used. And can be used as a negative photosensitive resin composition.

The plastic optical waveguide material of the present invention is
Although it can be used for the core layer of the optical waveguide, it can be used for the cladding layer by adjusting the optical refractive index. Further, it can be applied to a structure similar to that of a generally manufactured single mode optical waveguide on a substrate. For example, there are a slab type, a ridge type, a buried type and the like.

A method of manufacturing an embedded single mode optical waveguide in the optical waveguide structure will be described with reference to FIG. First, a precursor solution of polybenzoxazole, which is a material for an optical waveguide of the present invention, is applied onto a substrate 1 made of silicon or the like by a method such as spin coating, and is cured by heating or the like to close a ring. Then, the lower clad layer 2 made of resin is obtained. Next, when the lower clad layer 2 is formed by using a precursor solution of polybenzoxazole, which is a material for an optical waveguide of the present invention having a higher refractive index than the polybenzoxazole used as the lower clad layer, The core layer 3 is formed by a method similar to. Next, a mask layer 4 for forming a core pattern is formed thereon (FIG. 1A). As the material for the mask layer, metals such as Al and Ti, SiO ₂ , spin-on-glass (SOG), Si-containing resist, and photosensitive polybenzoxazole can be used.

Next, a resist is applied on the mask layer 4 and prebaked, exposed, developed and afterbaked to obtain a patterned resist layer 5 (FIG. 1).
(B)). Next, after removing the mask layer 4 not protected by the resist layer 5 by etching (FIG. 1C), the resist layer 5 is removed by an etching solution, and the polybenzoxazole of the core layer 3 is removed by the mask layer 4. It is removed by dry etching (FIG. 1D). When Si-containing resist or photosensitive polybenzoxazole is used for the mask layer 4,
There is no need to use photoresist.

Next, the remaining mask layer 4 is removed by dry etching or using a peeling liquid. (Fig. 1
(E)). Further, a polybenzoxazole precursor, which is the same material for the optical waveguide of the present invention as that used for the lower clad material, is applied thereon by spin coating or the like to form an upper clad layer 6, and this is formed. The upper clad layer 6 which is cured by heating and closed to obtain a resin is obtained (FIG. 1 (f)). In this way, a single mode optical waveguide made of polybenzoxazole resin having good optical waveguide characteristics such as optical loss can be manufactured.

A single mode optical waveguide made of a fluorine-containing polybenzoxazole resin obtained by ring-closing the precursor solution of the fluorine-containing polybenzoxazole, the polybenzoxazole copolymer and the mixture, which is the material for the plastic optical waveguide of the present invention, is prepared. As a result, it is possible to reduce the difference in the optical waveguide characteristics such as the optical loss in the optical waveguide with respect to the polarized wave.

[0026]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited thereto.

Synthesis Example 1 2,2-bis (3-amino-4-hydroxyphenyl)
73.2 parts (0.2 mol) of hexafluoropropane was dissolved in 200 parts of dried dimethylacetamide, and after adding 39.6 parts (0.5 mol) of pyridine, 2 parts was added to 100 parts of cyclohexane at -15 ° C under dry nitrogen. , 2-bis (4-carboxyphenyl) -hexafluoropropane chloride dissolved in 85.8 parts (0.2 mol) was added dropwise over 30 minutes. After the dropping was completed, the temperature was returned to room temperature and the mixture was stirred at room temperature for 5 hours. Then, the reaction solution is distilled water 7L
Then, 143.1 parts of polybenzoxazole precursor (A) was obtained by collecting the precipitate and drying it. When the molecular weight of the precursor was measured by gel permeation chromatography (hereinafter abbreviated as GPC), it was 22.0
It was 00. The refractive index was 1.521.

Synthesis Example 2 2,2-bis (3-amino-4-hydroxyphenyl)
Polybenzoxazole was produced in the same manner as in Synthesis Example 1 except that 73.2 parts (0.2 mol) of hexafluoropropane was replaced with 56.0 parts (0.2 mol) of bis (3-amino-4-hydroxyphenyl) sulfone. Precursor (B)
127.6 parts were obtained. When the molecular weight of the precursor (B) was measured by GPC, it was 23,000. The refractive index was 1.545.

Synthesis Example 3 2,5-bis (4-carboxyphenyl) -hexafluoropropane (85.8 parts, 0.2 mol) was added to 4,4'-
Oxybisbenzoic acid chloride 59.0 parts (0.2mo
130.3 parts of a polybenzoxazole precursor (C) was obtained in the same manner as in Synthesis Example 1 except that it was replaced with l).
When the molecular weight of the precursor (C) was measured using GPC, 2
It was 4,000. The refractive index was 1.586.

Synthesis Example 4 Except that 85.8 parts (0.2 mol) of 2,2-bis (4-carboxyphenyl) -hexafluoropropane was replaced with 95.4 parts (0.2 mol) of perfluoroazelainyl chloride. In the same manner as in Synthesis Example 1, 151.7 parts of polybenzoxazole precursor (D) was obtained. When the molecular weight of the precursor (D) was measured by GPC, it was 23,0.
It was 00. The refractive index was 1.513.

Synthesis Example 5 2,2-bis (3-amino-4-hydroxyphenyl)
Hexafluoropropane 73.2 parts (0.2 mol) was added to 9,9-bis (4-((4-amino-3-hydroxy))
Phenoxy) phenyl) fluorene 76.0 parts (0.2
mol), 2,2-bis (4-carboxyphenyl)
-Hexafluoropropane chloride 85.8 parts (0.2
45.0 parts (0.2 m) of azelaic acid chloride
ol), and in the same manner as in Synthesis Example 1, 108.9 parts of polybenzoxazole precursor (E) was obtained.
When the molecular weight of the precursor (E) was measured by GPC, 1
It was 8,000. The refractive index was 1.621.

Synthesis Example 6 2,2-bis (3-amino-4-hydroxyphenyl)
Hexafluoropropane 73.2 parts (0.2 mol) was added to 9,9-bis (4-((4-amino-3-hydroxy))
Phenoxy) phenyl) fluorene 76.0 parts (0.2
mol), 2,2-bis (4-carboxyphenyl)
-Hexafluoropropane chloride 85.8 parts (0.2
was replaced with 41.8 parts (0.2 mol) of 1,4-cyclohexanedicarboxylic acid chloride to obtain 106.0 parts of a polybenzoxazole precursor (F) in the same manner as in Synthesis Example 1. The molecular weight of the precursor (F) is G
It was 23,000 when measured using a PC. The refractive index was 1.618.

Synthesis Example 7 2,2-bis (4-carboxyphenyl) -hexafluoropropane 85.8 parts (0.2 mol) was replaced with 2,2-bis (4-carboxyphenyl) -hexafluoropropane 77.2 parts. (0.18 mol) and 4,4′-oxybisbenzoic acid chloride 5.9 parts (0.02 mol), except that the mixture was replaced with the same manner as in Synthesis Example 1, polybenzoxazole precursor (G) 140.8. I got a part. When the molecular weight of the precursor (G) was measured using GPC, 24,
It was 000. The refractive index was 1.528.

Synthesis Example 8 2,2-bis (3-amino-4-hydroxyphenyl)
Hexafluoropropane 73.2 parts (0.2 mol) was added to bis (3-amino-4-hydroxyphenyl) sulfone 56.0 parts (0.2 mol), and 2,2-bis (4-carboxyphenyl) -hexafluoro. Propane 85.8
Parts (0.2 mol) to 2,2-bis (4-carboxyphenyl) -hexafluoropropane chloride 77.2 parts (0.18 mol) and 4,4'-oxybisbenzoic acid chloride 5.9 parts (0.02 mol). 125.2 parts of a polybenzoxazole precursor (H) was obtained in the same manner as in Synthesis Example 1 except that the mixture was replaced with the mixture of 1). It was 22,000 when the molecular weight of the precursor (H) was measured using GPC. The refractive index was 1.551.

Synthesis Example 9 2,2-bis (3-amino-4-hydroxyphenyl)
Hexafluoropropane 73.2 parts (0.2 mol) was added to 2,2-bis (3-amino-4-hydroxyphenyl)
Hexafluoropropane 65.9 parts (0.18 mol)
And bis (3-amino-4-hydroxyphenyl) sulfone 5.6 parts (0.02 mol) in a mixture of 2,2-
Similar to Synthesis Example 1 except that 85.8 parts (0.2 mol) of bis (4-carboxyphenyl) -hexafluoropropane was replaced with 59.0 parts (0.2 mol) of 4,4′-oxybisbenzoic acid chloride. Thus, 117.5 parts of polybenzoxazole precursor (I) was obtained. Precursor (I)
It was 24,000 when the molecular weight of was measured using GPC. The refractive index was 1.592.

Synthesis Example 10 2,2-bis (4-carboxyphenyl) -hexafluoropropane chloride 85.8 parts (0.2 mol) was replaced with perfluoroazelainyl chloride 85.9 parts (0.18).
mol) and 4,4′-oxybisbenzoic acid chloride 5.
Polybenzoxazole precursor (J) 14 was prepared in the same manner as in Synthesis Example 1 except that 9 parts (0.02 mol) was replaced.
8.6 parts were obtained. The molecular weight of the precursor (J) was 24,000 as measured by GPC. Refractive index is 1.5
It was 19.

Synthesis Example 11 2,2-bis (3-amino-4-hydroxyphenyl)
Hexafluoropropane 73.2 parts (0.2 mol) was added to 9,9-bis (4-((4-amino-3-hydroxy))
Phenoxy) phenyl) fluorene 76.0 parts (0.2
mol), 2,2-bis (4-carboxyphenyl)
-Hexafluoropropane chloride 85.8 parts (0.2
2,2-bis (4-carboxyphenyl)-
Hexafluoropropane chloride 8.6 parts (0.02 m
ol) and azelaic acid chloride 40.5 parts (0.18 m
ol) in the same manner as in Synthesis Example 1 except that the polybenzoxazole precursor (K) 112.6 was used.
I got a part. When the molecular weight of the precursor (K) was measured by GPC, it was 23,000. The refractive index was 1.615.

Synthesis Example 12 2,2-bis (3-amino-4-hydroxyphenyl)
Hexafluoropropane 73.2 parts (0.2 mol) was added to 9,9-bis (4-((4-amino-3-hydroxy))
Phenoxy) phenyl) fluorene 76.0 parts (0.2
mol), 2,2-bis (4-carboxyphenyl)
-Hexafluoropropane chloride 85.8 parts (0.2
2,2-bis (4-carboxyphenyl)-
Hexafluoropropane chloride 8.6 parts (0.02 m
ol) and 1,4-cyclohexanedicarboxylic acid chloride (37.6 parts, 0.18 mol) were replaced with a mixture, and polybenzoxazole precursor (L) (110.0 parts) was obtained in the same manner as in Synthesis Example 1. It was The molecular weight of the precursor (L) was measured by GPC and found to be 25,000. The refractive index was 1.612.

Example 1 Production of Optical Waveguide: The polybenzoxazole precursor (A) synthesized in Synthesis Example 1 was applied onto a silicon substrate by spin coating to form a film. The formed thin film is 320
It was cured by heating at 0 ° C. for 1 hour to form a lower cladding layer. Then, a core layer was formed thereon by spin coating using the polybenzoxazole precursor (F) synthesized in Synthesis Example 6. No intermixing was observed between the lower clad film and the core film.
The formed core layer was cured by heating at 320 ° C. for 1 hour.

Next, an aluminum layer having a thickness of 0.3 μm was vapor-deposited on this core layer to form a mask layer. Next, a positive photoresist (diazonaphthoquinone-novolak resin system, manufactured by Tokyo Ohka, trade name OF
After applying PR-800) by spin coating, about 9
Prebaking was performed at 5 ° C. Next, a photomask (Ti) for pattern formation is 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, trade name NMD-3). And developed. After that, 135 ℃
I did a post bake. As a result, a linear resist pattern having a line width of 8 μm was obtained. Next, wet etching of aluminum was performed to transfer the resist pattern to the aluminum layer. Further, using the patterned aluminum as a mask, the polybenzoxazole of the core layer was processed by dry etching. Next, the aluminum on the upper layer of polybenzoxazole was removed with an etching solution. Furthermore, the same polybenzoxazole precursor (A) as that of the lower clad layer was applied thereon by spin coating. This coating film was heat-treated at 320 ° C. for 1 hour to form an upper clad. Finally, both ends of the optical waveguide were cut off with a dicing saw to form light input / output end faces. In this way, an embedded single mode optical waveguide was obtained on the silicon substrate.

When the insertion loss of the buried type single mode optical waveguide obtained above was measured, the wavelength was 1.3 μm.
0.3 dB / cm or less and 0.3 dB / c at 1.55 μm
It was m or less. Further, the polarization dependence of the insertion loss was 0.5 dB / cm or less at both the wavelength of 1.3 μm and the wavelength of 1.55 μm. Furthermore, the loss of this optical waveguide is 75 ° C / 9
Even under the condition of 0% RH, it did not change for more than 1 month.

Examples 2 to 6 were carried out in the same manner as in Example 1 with the combinations shown in Table 1. The evaluation results are shown in Table-1.

Comparative Example 1 2,2'-bis (trifluoromethyl) -4,4'-diaminobiphenyl 6.4 parts (20.0 mmol) and 2,
2-bis (3,4-dicarboxyphenyl) hexafluoropropane dianhydride, and dimethylacetamide 8
It was dissolved in 6.6 parts and stirred at room temperature under a nitrogen atmosphere for 3 days to cause a reaction to obtain a polyamic acid (M). The molecular weight of this polyamic acid was measured by GPC and found to be 14,000.
Met. The refractive index was 1.523.

The polyamic acid (M) obtained above was used for the core layer, and the polybenzoxazole precursor (D) obtained in Synthesis Example 4 was used for the upper and lower clad layers. In the same manner as in 1, an embedded single mode optical waveguide was prepared and evaluated. The results are shown in Table-1.

[0045]

[Table 1]

[0046]

INDUSTRIAL APPLICABILITY The plastic optical waveguide material for optical communication of the present invention is excellent in electrical characteristics, heat resistance and transparency, can be realized at a low cost and has a large area, and is particularly suitable for optical communication. It is useful for optical waveguides with high transparency in the near-infrared wavelength range and low optical loss.

[Brief description of drawings]

FIG. 1 is a process chart showing an example of a method for producing an embedded optical waveguide according to the present invention.

[Explanation of symbols]

1 substrate 2 Lower clad layer 3 core layers 4 Mask layer for forming core pattern 5 Resist layer 6 Upper clad layer

   ─────────────────────────────────────────────────── ─── Continued front page    F term (reference) 2H047 KA04 PA02 PA15 PA24 PA28                       QA05 TA11 TA41                 4J043 PA01 PA04 PA08 PA19 QB15                       QB23 QB24 QB33 RA06 RA52                       SA06 SA47 SA71 SA72 SB01                       SB02 TA12 TA26 TA32 TB02                       TB03 UA042 UA131 UA132                       UA231 UA762 UB021 UB022                       UB061 UB062 UB121 UB122                       UB151 UB152 UB281 UB282                       UB301 UB302 XA13 YA06                       ZA12 ZA31 ZA41 ZA51 ZA52                       ZB21

Claims (2)

[Claims] 1. A plastic optical waveguide material comprising a polybenzoxazole resin obtained by ring-closing a polybenzoxazole precursor having a structure represented by the general formula (A). [Chemical 1] (However, m and n in the formula are m> 0, n ≧ 0, and 2 ≦ m.
+ N ≦ 1000, and 0.05 ≦ m / (m + n) ≦ 1
Is an integer that satisfies. R _{1 to} R ₄ represent a hydrogen atom or a monovalent organic group, X is a tetravalent group selected from the groups represented by formula (B), and Y ₁ and Y ₂ are represented by the formula (C ) A divalent group selected from the groups represented by ) [Chemical 2] [Chemical 3] (However, in the formula (B) and the formula (C), X ₁ and X ₂ are the formula (D).
A divalent group selected from the groups represented by Also,
I, j, and k in the formula (C) each represent an integer of 2 to 10. In the structures represented by the formulas (B) and (C), the hydrogen atom on the benzene ring is a methyl group, an ethyl group,
It may be substituted with at least one group selected from propyl group, isopropyl group, butyl group, isobutyl group, t-butyl group, fluorine atom, trifluoromethyl group and chlorine atom. ) [Chemical 4] 2. An optical waveguide comprising a core layer formed of the plastic optical waveguide material according to claim 1.